Joe Stocco, MN ATMA-SPHERE MA-1 mkII and Manapan MG20 (4 ohms)
"I believe the ZEROs are a significant improvement for all Magnapan based systems and most likely for all Atma-Sphere driven speaker systems. I have listened to Paul's Zeros in my system. I don't know anything about circuits and electronics but I do trust my ears! In my system the Zeros are immediately audible. Better bass response with more resolution and dynamics in my MG20s. If you have Magnepans I think you will like the Zeros. I am anxiously awaiting mine. Joe Stocco"

"Wanted to comment on this post. I have always per Ralph's suggestions placed my AS amps directly behind and connected to my Maggies with the shortest workable speaker cable, this is about 12 to 18 inches. When I received my Zeros I simply hooked them up in place of the speaker cable, that is, direct from amp to speaker. I have not experimented otherwise but the sound is, in my opinion, awesome. This has completely eliminated the effects of cabling. Try it! "

"Received my zeros about two/three weeks ago and wanted to give them a good audition before posting my comments. I connected them bi-wire fashion to my Magnepan MG 20's with the 2X leads to the mid/hi inputs and the 4X leads to the bass panel inputs. I have been so happy with this setup that I have not yet experimented with other possibilities. The biggest improvement was to bring the bass out of the background with more authority and weight. The mids and highs were more transparent with more resolution. I love my zeros. I can't imagine a better upgrade at several times of the cost of the zeros. My system includes A-S MP 1, A-S MA1,MK2, and Magnepan MG20s. Thanks Paul for bringing us these Zeros."

Keith Thomson, BC Atma-Sphere M-60 and nOrh 9 speakers (8 ohm nominal)
"My Zero's arrived on Friday but I have not had a chance to listen until tonight. Big improvement with my nOrh 9's. My speakers were very under damped without the Zero's, sounding pretty flabby in the bass. I had tried many things to make them work well with my M60's with no luck. The Zero's are just what was needed for me. I have tried the 2x and am now listening to 4x. (Finding 4x is slightly dry also) 2.75x will be tested tomorrow."

Meridian 508.24, MP3, M60 MkII's, nOrh 9's, 6'Jena 7 braid speaker cable

"I have had to return one of the 5.5inch Revelator drivers to Scan-speak from my nOrh 9's so I put the Meadowlarks back into my system with the M60's to see how they work with the Zero's. Another positive! 2.75x seems to work the best. I tried listening to 2x and 4x afterwards and there is no contest."

"X 2.75 works very well for me.....Sunny Spring day and I am inside, cannot stop listening! Keith."

Bryan Petersen, BC Atma-Sphere M-60 and nOrh 9.0 Speakers (8 ohm nominal)
"I have not been able to hear the Zeros in my system the way I want to, because I am awaiting the arrive of my new MP3 pre amp. I am listening to them by removing the V2s in my M60's and running my CD player directly to the M60's. The sound is very detail with greater control in the bass. My speaker are the nOrh 9.0 marble, which are 8 ohms, but dip to 5.4 ohms at 2500 Hz. I am running them at 2.75x. I will write you a complete summary when I get my MP3. Cheers"

"Thanks Paul, for making my nOrh 9.0 marbles sound even better then they ever have. They sound like they are now being driven by a 100 watt OTL amp. Much better top to bottom over all performance. This is the best system tweak I have done to my system. "

"I and two other Atma-Sphere owners on the west coast are using nOrh 9.0 speaker. They are a two way speaker with outstanding performance for the money. The Paul's Zeros make them over the top, great detail and very musical."

"Amen, AMEN : PREACH ON......This how I feel after going to a MP3 and Zeros in my M60 system. Cheers Bryan"

"I know of three Atma-Sphere M60 owners that have 8545 woofer in their speaker systems. For me the Zero's give great detail and control in the lower bass and more energy. The marble cabinet on the nOrhs are very close to resin free, so you get to hear what the woofer can really do. They are outstanding drivers. If someone told me that a five and half inch driver could go down to 35 Hz before I listened to the 8545 I would of though that they where smoking something funny. I would highly recommend a pair of Zeros."

Nicholas Fosteras, London Atma-Sphere and B&W Nautilus 805 Speakers
"Anyway - spent the weekend listening (at 2x tap) and WOW! I've never been happy with my current set-up. I am using a pair of B&W Nautilus 805 speakers which I would like to change, but because I'm moving all over the world, the size is good for me. But the zeros have transformed them. Much tighter control, significantly more bass and as a result the sound stage sounds much better. I use a digital source, and find it far less fatiguing now. So - thanks - good job! I look forward to your next 'discovery'."

Gary Tong, OH A-S M-60 (6336 mod) and Dynaudio Confidence 5 (4 ohms) Spk
"I definitely will let everyone know how great these Zeros work. Preliminary result sounds great. Using a 16ga cable (zip-chord cable, my speaker cables use banana plugs on both end, I will modify my setup this weekend) on one speaker with the 2X setup. Initial turn on the music, it sounded dull. After 2 minutes of listening ,the music took a 180 degree turn for the better. (I guess the Zero's core needs warm up too) Increase bass and more refined detail on the music compare to the other non-Zero speaker. I spent only 15 minutes and I got to run out for a ball game. I will modify my setup and try other Z-factors and post my finding on ASOG. My speakers (Dynaudio Confidence 5) measures 3.6 ohm on my DMM. Thanks , Gary"

"I got my Zeros last week. I also experienced huge improvement on the bass definition and the musics have more refined details. I have tried all the Z-factors and found 2.75X has the best sound on my speakers. (Dynaudio Confidence 5, 4 ohm impedance) Thanks Paul for your newly Discovery."

Mark Gilmore, CA A-S, VAC, BAT, ARC, 211 SET amps and Carver Amazing Platinum MK IV Speakers (8 ohm)
"I finally had time to check out the Zeros on my "MA-30s" last night. You can see a picture of them at http://www.condor-connection.org/asog/pix/mg/top.html. They have only four 6AS7Gs per chassis. They are really much like an M-60 MK II with half the output tubes. They are really load sensitive. With the ZEROs hooked up for 4X impedance multiplication, I'm most impressed. They are now doing almost a full 20 watts into my speakers. These little amps now have the rich and deep bass I enjoy and the mid-band is smooth and extended. They run very cool, so now I'm ready for the onslaught of Summer in Southern California. I suspect they may not deliver the sound I'm looking for during rolling blackouts, but now the impact on my air conditioner will be tolerable. Well done, Paul! "

"I tried a 2:1 autoformer (ZEROs), with 4 ohm nominal speakers, and used the 8 ohm tap with a big VAC, BAT, AR and a 211 based SET amp with AudioNote output transformers. The sonics were better in all cases, using the 8 ohm tap, but not necessarily for the same reasons. During my tests, I could not explain the results. I had many ears confirm my observations. Later, I did my own research to learn what was happening. There's lots of good output transformer documentation available. I urge you to do your own research and try some good autoformers on your own. Originally I only wanted autoformers to use with my OTL amps. Later, I decided to try some experiments on transformer coupled tube amps. That is when I soon realized some thinking outside the box was in order. Now I know what so many AR amp owners use autotransformers."

Ray Shepherd, GA A-S M-60 and Montanna PBN SP Series II (5 ohm min)
"I've had the ZEROs in use for four weeks now and my experience pretty much tracks with others who have commented. I've done little experimenting other that using them for a couple weeks at either end of the speaker cable at 2X connection. Paul's suggestion that the ZEROs work better closer to the speaker proved correct to my ears as well, so I've connected the 2X leads directly to jumpered bi-wire terminals and foregone bi-wiring also. Sound in my system is everything I'd hoped for. Bass is better articulated and has more punch. There's a sense that the music is more present in the room without being overly detailed or etched in any regard. The ZEROs have proved an excellent addition and greatly expanded the potential of my system. Hats off to Paul for exceeding all expectations with the ZEROs. Bravo!! "

P.S. For what it's worth, my system is: Linn LP 12 w/Naim ARO & Clearaudio Arum Beta S Rotel RCD 970 CD to MSB Link III Fisher KM-50 tuner AS MP-1 AS M60 Mk. II Montanna PBN SP Series II(5 ohm min impedance;90 db)

"Is it possible to offer longer leads on the next batch of Zero's for those who would like to eliminate speaker cable? I know in my case, an additional 2 ft. on the amp leads would have allowed me use the Zeros direct (no speaker cable) without altering my system set-up. Could be a big plus for some of those considering the Zeros for their system."

Good idea Ray. The ZEROs now come with 24" speaker leads and 48" amplifier leads. paul

Travis Franklin, TX Atma-Sphere MA-1 and Magnapan 3.6 (4 ohm)
".... two of my techie friends were impressed with the construction. I think they do what they are designed for. I finally got my 3.6s and powered them up with 12 tube MKII MA-1s, seeing a new MP-3. Without the Zeros the MA-1s were huffing and puffing. I think anytime you see blue lights pulsing in time to the music, it may be a pretty sight, but it's a sign of stress. With the Zeros in circuit at 2.75X, no more pulsing blue lights, more detail, tighter bass. This is what I got from the change. I might try playing around with 2X, but maybe not. Frankly, I think they're a bargain at the price (don't you dare go up in price :)) and just what the doctor ordered. I'm glad I had the foresight to buy them ahead of time. Thanks for all your efforts on behalf of amplifier owners everywhere. This does the job. Best,Travis Franklin."

"I have the 12 tube version of the MA-1 MKII. I find with the 3.6s AND the Zeros that it is sufficient for the amount of volume I like. I like Mahler, UP, with my Velodyne 12s. I might could do with a little more headroom but only if I had more dollars than sense. I now have the Zeros connected between the Maggies and the Atmas with no speaker wire. I can hear the improvement and I tend not to hear those kinds of differences. Recommended."

"I was one of the first adopters because I knew that I was eventually going to have Magneplanar 3.6s and, as a hedge against disappointment with 12 tube MA-1 MKIIs soon to be driving them, I thought it a wise plan to get a pair of Zeros. Good idea. I did get a pair of used 3.6s last Friday (thanks Audio Systems in Austin, Texas) and good sounds started happening at my Audio Altar, as Mark Gilmore likes to call it. Before inserting the Zeros I tried the combo Zero-less. Good, but pulsing blue lights in time to the music was not a sight I wanted to see, however attractive. Upon insertion of the Zeros at X2.75, making the amps see an 11 ohm impedance instead of 4, things got very much better. Bass tightened up a bit, surprising to me was the detail that started appearing in the mid-range, and, no more pulsing blue lights, which meant that the A-Ss were working much more easily. As you-know-who likes to say, it was a "good thing". I have no reservations about the Zeros whatsoever, and recommend them to any Maggie/A-S combo owner, you lucky dogs you. Incidentally, THIS is the sound stage I've been looking for and it's only going to get better with minor tweaking. Hallelujah! "

George May, IL Atma-Sphere M-60 and Merlin VSM-SE (8 ohm) "After only a few hours listening it may be a little premature, but I think the ZEROs and one pair of M-60s may be nearly equal to my M-60 x 4 set up. I'll be able to reduce the heat output as we get into summer weather."

"In my current standard 2 amp system, connecting them that way resulted in the best over-all sound I've attained so far - very nearly the same intensity in the bass as my previous 4 amp system, but retaining a subtle sweetness in the highs and mids that was occasionally lacking in the doubled-up amp arrangement. FWIW: It was pointed out to me that, while I was using quality speaker cables, they were 14 feet long, which may partly explain why there was such a substantial improvement when the cables were by-passed."

"Now, the combination of ZEROs and one pair of amps seems to be the best of both worlds - deeper but less forward sound stage, and, to my ears, (which also have a little tinniness) near perfect bass."

"The bass alignment module increases the tactile feel of the bass, but I preferred the sound without it - until I added the ZEROs to the system. Now I have the M60s connected to VSM-SEs by way of Paul Speltz' ZEROs (no speaker cable per se). The result is sensational. Soundstage is deep and wide. There is more definite separation between instruments, the sound of percussion has startling initial impact. I do not find a trace of dryness in the midrange, unless using the X4 or greater tap on the ZEROs. When I added the Merlin BAM to the M60-ZEROs-VSM-SE system, a recent guest was sure I had a subwoofer in the room."

"I've listened briefly to a variety of combinations. Multiplication factor of 1.37 made no difference, at factor of 4 the sound seemed dry, and x 2 seems just right. One pair of M-60s with ZEROs (X factor 2) is almost the equal of two pairs of M-60s bridged (without ZEROs). The difference is subtle, mostly a little less pizzazz in the bass with one amp per speaker. But there seems to be more clarity and definition in the highs with the ZEROs. Nevertheless, I am disappointed to report that I will not be able to abandon my four -amp set up after all. No combination I've tried sounds better than my bridged M-60s plus ZEROs. I'll keep experimenting and listening."

"A year or so BZ (before ZEROs) I tried moving the amps close to the speakers to allow a very short run of speaker cable. There was a subtle improvement, but it certainly was not a big difference. Today I moved the ZEROs and amps to a small stand behind the speakers and made the connection directly by way of the ZEROs' leads, eliminating the speaker cable. Instead of trying to describe the new sound, I'll just say, Guys, you 'gotta try this!!! I was using a quality speaker cable, biwire JPS Labs Superconductor +. Now I can go back to using just two M-60s instead of my four-amp set up."

"When I installed Paul Speltz' ZEROs I felt that I could abandon the four-amp setup, the improvement was so great. Only recently have I tried four M-60s plus ZEROs. Sorry I can't do a real audiophile description - just WOW!!! "

Morgan Lundberg, Sweden
"Hi Paul,I finally got them today. They're beautiful - and HUGE, much bigger than I thought they'd be. Great looks. Thank you so much for your kind services! "

Dave Hiestand, CA Atma-Sphere M-60 and DIY transmission line Merlin VSM (6 ohm min)
"I received the zeros about 2 weeks ago and I thought I would share my experience with the group. First a little background. I have been following the group for about 3 years and I have been keeping up with most of the tweaks for the M 60s i.e. extra output capacitance, grid stop resistors, input pi-filters, Teflon coupling caps, SLCF, HEXFREDs, 12sx7s etc. You could say I'm a little tweaked, but I can't be said to be ultimately tweaked... yet. I am running the Merlin VSM drivers in a DIY transmission line cabinet so the amps and now the zeros were/are seeing about a 6 ohm minimum resistance. When I received the zeros I first tried them at the 2x setting. They really improved the sound especially in the bass region. Sorry there will be no TAS flowery descriptions. Next I tried the 4x setting and as advertised the sound seemed to become almost solid state like. My latest experiment is running them in the 16x setting with 2 tubes per a chassis. It really sounds good. Doesn't have an abundance of power, but for most music it is acceptable. It sounds even better when I think of summer coming and when I consider the future cost of electricity in California. My next project will be to make summertime amps with one? or two output tubes each. Perhaps then I will try the 6336's."

John Fisher, Australia DYI MA-1 and M-L Request speakers
"Hi Paul,I've just received my Zero's and I am very pleased with the result.The quality of manufacture is also to a high standard. I would like to personally thank you for your kind assistance. Keep coming up with great ideas, Best regards, John Fisher."

"Well I have finally had the time to do some serious listening to my recently modified,heavily tweaked,homegrown MA-1?+ZERO+M-L Request combo and the result is quite positive,more solidity and greater control in the bass,slightly more resolution in the midrange with a nicer feel to the sound,perhaps a not so lean sounding mid with more top end sparkle.Overall a big improvement.I can also push the speaker a bit more without the sound congesting.Well for my ears the Zero's have solved what appeared to be a mismatch.It would be interesting to try some real high powered tube amps like AR reference 600 monoblocks to see if there is any further gain to be had or whether at a certain point the extra power on tap remains just that.In any case my gratitude to Paul for a most worthwhile contribution."

Greg Hutchison, WA Atma-Sphere M-60 and Quad 989 "The ZEROs are doing a beautiful job on the 2.75x tap - 4x is still a bit 'over the top'. I did a couple of things since my last e-mail to you. I re-checked the bias on both amps after running for three hours and found it to be somewhat on the low side (~525ma across the speaker terminals). More importantly I spent an hour or two listening to my Quad 405.2 (S/S, 100W into 8ohms) drive the 989s. (This was the amp I used before the M60's). Absolutely remarkable the difference in tonal balance between the two; when I first went to the M60's from the 405.2, my initial impression was one of rolloff but I let it go because the M60's are so liquid and seductive. Putting the 405.2 back showed just how much was missing. Going back to the M60s/ZEROs was something of an epiphany. Bass is abundant and the mids are sweet. I'm at a loss to say why my initial impressions where so negative - the low bias perhaps ? ears conditioned to expect a certain sound ? Thanks for both the ZEROs and your help in getting them in the groove." Greg

Mike Kasper, WA Atma-Sphere M-60 with Klipsch Chorus Speakers (101dB, 8 ohm)
"I've barely had time to play with and experiment with different loading with my new ZERO's that came in about the same time from Paul S. I'm in the middle of rebuilding the "transformer interfaces" on a pair of Acoustat 2 + 2 vintage electrostatic panels. In the meantime I'm running some low-fi Klipsch Chorus speakers that are quite efficient (101 dB SPL). I think these speakers are rated at nominal 8 ohms, and with the ZERO's set for 2x impedance, they sound great with the M60's. I tried 2.75x and that was pretty nice, too. At 4x everything seemed to "compress" to the point that the entire range was less dynamic and something was missing. I'm sorry I don't think I'll ever make a writer for audio review, but with the 2x impedance boost everything seemed to open up even more than with the direct connection with the M60's - if that is possible. The ZERO's are another amazing addition to my system."

Lew Markoff, MD Atma-Sphere MA-240 and SoundLab U2 (2-100 ohm)
"I don't quite know how to separate the obvious benefits of the Zeros from their inherent sonic signature, except to say that I am certain they have a very minimal intrinsic sonic effect, if any. One way to think about it is to listen with the Zeros at some step-up ratio below the threshold for their beneficial effects on impedance. I think in my system, the Zeros were doing very little to help my amps when I was using the 2X taps. So I can compare the sound with Zeros at 2X vs my previous Goertz silver spkr cables. (Now that I have the Zeros in place, I have done away with spkr cable entirely.) It is possible that the Zeros at 2X were ever so slightly more "edgy" sounding than the Goertz silver. But this was an immediate impression, without the benefit of breaking in the Zeros. At 2.75X, the sound is so much improved in tonal balance that I could never hear the "edgy" effect; it was that slight. Moreover, I noticed that the Zeros do get noticeably better after several hours of use. Application of some isolation techniques and damping to the Zeros also helped get rid of that teeny tiny edgy effect (meaning that I sat them on some bubble wrap and weighted them down with stones from my wife's garden.) "

"It seems counter-intuitive to us members of the "less is more" school of audiophilia, but I agree with Paul. I definitely hear more low level detail WITH the Zeros vs without."

"you should GAIN "efficiency", in the sense that the MA1 will drive a 16-ohm load more efficiently than it will drive a 4-ohm one. And if you read Paul's postings, you will note that he was very careful to select a design that was as low as possible in resistance, which IS one possible way that you could lose some efficiency by installing the ZERO between an MA1 and the Eidelon. IMO also, it's not just that the amp will put out more measurable Watts into 16 ohms than into 4 ohms, it will also sound a lot better, with noticeably better bass control and detail (which is exactly what ZERO-users are reporting, too). In other words (and this is more related to my own listening experiences) when an OTL is driving a too-low impedance, other distortions seem to happen that result in suboptimal sonics that may not be purely related to a lack of power transfer per se."

"I really did not think I "needed" the Zeros to drive my U2s, because the Sound Lab factory claims a nominal 8-ohm impedance for this and others of their full-range ESLs. So, I figured that like most ESLs, Z was probably >8 ohms in the bass end and then gradually fell to below 8 ohms only at treble frequencies, where power demands are minimal. (That would fit MY definition of a nominal 8-ohm spkr load.) A review of Kevin Covi's articles reminded me that he actually measured quite low Z for his A3s at mid-range frequencies (<2 ohms!!!), while at the extreme low end, Z is >100 ohms. No wonder I had always had a vague sense of a mid-bass and low mid-frequency "suck-out", making my spkrs sound the slightest bit "lean". But since that was their only sonic flaw, I was happily living with it. The Zeros have changed all that. Even at 2.75X the effect is better than Prozac. I can only imagine what 4X (my estimate of the real optimal ratio for my spkrs) will do. At 2.75X, bass is tighter or at least "as good", but the midrange has come alive, more real sounding on vocals and jazz saxophone, etc., and oddly or not, treble seems more extended, too. Thank you, Paul."

"The Zeros will markedly reduce the current demand on your amps (read, output tubes). Paul did not make me say that, honest. My system sounds hugely improved with Zeros between U2s and MA240s, whereas I already loved the combination in the pre-Zero era."

Chuck Bottemiller, MN Bel Canto SE-845 and QUAD 63
Using the ZEROs to 4x a pair of QUAD 63s being driven by a SE 845 tube amp on its 8 ohm tap (no 16 tap ohm available), compared to driving the QUADs straight off the 4 ohm tap, reduced the artificial sounding SE 2nd harmonic distortion "bloom", increased the top end speed, and brought more presence and life to the music.

Alan Yanowitz, MN Atma-Sphere M-60 and Silverline Sonatas (8 ohm) Speakers
"My M60s drive Silverline Sonatas (original version). They are a very easy load to drive (96 db, relatively flat 8 ohms). I have been using the zeros for over a month. I am delighted. I was very happy with the set up before buying the zeros. I was interested in trying them on my second system where I have a Magneplanar 1.6QR running on solid state (I had been thinking about running tubes with the Maggies - and I felt that they lacked some drive and coherence on more complicated passages on the M60s. However, I first connected them to the Sonatas, not expecting a great deal.) The zeros increased the information I was hearing, and seemed to increase the power and drive, without any negative side effects. The zeros are connected in the 2x mode and they are going to stay connected to the Sonatas and m60s. I have not yet connected the amps directly to the speakers with the zeros, but I will do that soon. Thanks Paul! "

Vinh Vu, NJ Transcendent Sound and Meitner STR50 Amps with Merlin ( 8 ohm ), Vandersteen (4 ohm), and Martin Logan (4 ohm) Speakers
"Transcendent Sound stereo OTL (25 watts into 8 ohms) with my Merlin VSM-Millennium speakers (8 ohms nominal) I made up some make shift 4ft biwire pair and connected between the Zero and the speakers, again at the 2x setting. The distortion was gone, the sound was cleaner, the resolution was astounding. The tighter bass was still present and I had a very happy medium of the OTL mid-range magic and the added resolution and tighter bass of solid state. Paul, I am really glad I tried the Zero. I don't fully understand all the technical underpinning but I trust my ear and I am hearing excellent sound from the Zero. It's a keeper!!! "

"Paul: I definitely want to buy another Zero for my other setup."

"Paul: I just came back from a friend's house where we tried the Transcendent Mono OTLs with half of the tubes removed with the Zero driving a pair of Martin Logan SL3. Works best at 4x."

"Yes, I did try the Zero on both the 25 w/channel Transcendent Sound OTL and the Transcendent Sound Super Compact 150 (150 w/channel with output trannys). Both work great with the Zero. The OTL drives a pair of Merlin VSM-M. I was using the SC 150 to drive the top of a bi-amp set up (PSE Studio IV at the bottom) for a pair on Vandersteen 4A (5-way design with a pair of passive 12-inch subwoofers). I had to use the biamp arrangement because the SC150 was laboring a little on orchestral pieces when driving the Vandys full range. With the Zero, I am using the SC150 to drive the Vandys full range at 4x setting. I am even going to try to use the OTL to drive the Vandys at 8x and 16x settings to see if they work. That is why I am buying the second pair of Zero. I also tried the Zero on a friend's setup (Transcendent Sound OTL monos with half of the output tubes removed, driving a pair of Martin Logan SL3s)."

"He is buying a pair of Zero too. All in all, can't say enough good things about the Zero. The increased resolution and bass is startling. Best investment in my system. Great product, Paul" Vinh Vu

"I too tried the Zero on my Stereo OTL driving a pair of Merlin VSM-M. Not only I am keeping it, I am buying another pair for my other setup. Works as Manuel described, more resolution, and tighter bass. The price is $383, great tweak for a nominal price. I also got rid of my pricey speaker cables because the Zero can work without speaker cables (it goes between the amp and the speaker). I loaned mine to a friend, who has the T8 monos. He was able to remove half of the output tubes (you can't with the stereo amp) and drived his Martin Logan SL3s (4 ohms) perfectly. Great addition to any OTL. I spoke to Paul Speltz personally. He is very helpful, generous with information, and a very nice guy." Vinh Vu

"I own a Transcendent Sound T8 stereo OTL, 25 watts/side into 8 ohms, paired with the Merlin VSM-M, and a pair of Zero autoformers, and never felt wanting for more power. Once you tried OTL, you will not go back to regular amps, tube or SS. Transcendent Sound just came out with a low power OTL kit, $1099 for a 15 watt stereo unit. Looks great and I am sure sounds great too. With the Zeros, you can get away with 15 watts."

"...on a whim, I decided to try my spare Meitner STR50 SS amp that I have laying around (a good amp in its days but I mainly use it as a back up). With the Meitner on top with the Zeros, and the PSEs back in the bottom, it sounds amazingly good. At the 2.75x setting, the top has resolution, weight, and plenty of punch. This is with a 50 watt amp. In fact, the only thing I am not happy with the sound now is the wooly bass actually (it goes deep, but like a home theater type of bass). I am thinking of trying the other set of Zeros to tighten the bottom as well. I will let you know how that works out. Anyway, I am surprised that the Zeros are so versatile. Imagine me being happy with the all-SS setup, me being a tube kind of guy. In fact, I had an audiophile friend over, a fellow NJAS member, and he swore there was some tube in the system. The sound is non fatiguing but quite punchy, especially for the Vandys. I may demo the Zeros with both tube and SS amps at the NJAS meeting." Vinh

If you need details about my setups, here they are:

Merlin Set Up: Merlin VSM-Millennium with Baterry BAM Transcendent Sound stereo OTL (25 watts/side) at 2x Zero setting Jeff Rowland Coherence One MkII solid state preamp Digital front: Musical Fidelity E624 CD player into ART DI/O DAC Analog front: Thorens TD-320MkII, Thorens arm, Sumiko SHO cartridge Cables: Millersound interconnects, Zeros wires for speaker cables

Vandersteen Set Up: Vandersteen 4A speakers with WX-4 external active crossover, with two sets of Zeros in a biamp arrangement: Meitner STR-50 (59 wats/side) stereo amp for the top, at 2.75x Zero setting PSE Studio IV monoblocks (100 Watts/side) at the bottom, at 1.37x Zero setting Digital Front: Sony DVP-S7000ES DVD player into ART DI/O DAC Analog Front: Thorens TD-160, Thorens arm, Audio Technica cartridge Cables: Millersound interconnects and speaker cables

So basically I am using the Zeros with both an OTL amp, and a strictly solid state setup that people told me sounds as good as a tube setup with tight bass. I also have used the Zeros with a transformer tube amp (Transcendent Sound Super Compact SC150) to good effect (but this has the least impact as the SC150 is as fast as a SS amp with good resolution).

O Lmeda Piero, Holland Atma-Sphere M-60 and Audiostatic DC12 (1-2 ohm min)
"I have received the Zeros 2 days ago. My system is Sony DVP-S7700, Sonic Frontiers SF2 mkII DAC, Passion Pro balanced passive preamplifier, Atmasphere M60 MKII, Audiostatic DCI2 with impedance corrector, Siltech pure silver cables, with Zeros connected directly between speakers and amp. Audiostatic is an 8 ohm speaker that, as most of electrostatics, goes down to 1-2 ohm at 20kHz. I have first tried x4, but the decaying of sound was too quick and unnatural. So my listening is with the x2 option. My first positive impression is that the distortion seems now very low, the sound is less stressed, highs more sweet, disappeared a sort of strange "resonance" on the high frequencies I had before. Low frequencies seem more balanced and a little more extended and voices more natural and less "electronic". Piano in particular is a lot more fluid and easy on the ear. I have found new sounds in some CD that I cannot hear before. I have only one observation. The sound before was dark, a result of the decreasing impedance with frequency. I was expecting a more brilliant sound but what I have is a performance on the highs similar to what I had before. Maybe the highs are more extended but the absence of distortion make them less noticeable? At this point I have a very important question: The frequency response irregularities related to low damping factor amplifiers connected with speakers with very variable impedance are increased or lowered by the insertion of Zeros? The published photo of impedance characteristics shows increased variations of impedance after the insertion of Zeros. In any case, thank you for the Zeros. I have had a good improvement. Piero

So to answer your question, it is true that a 4 ohm speaker with 1 ohm of variation will turn into a 16 ohm speaker with 4 ohms of variation using the ZERO 4X, so it may appear that the variation has increased. But in proportion to the impedance the variation is still the same. The ZEROs will help equalize frequency response variations due to impedance variations by pushing the speaker's impedance into a more gradual region of the M-60's power transfer function. paul

Manuel Vidal, San Juan PR Transcendent OTL and Soliloquy 5.3 Speakers (90dB, 8 ohm)
If you want to know what difference a 16 ohm impedance speaker sounds like with our OTL's give Paul Speltz' Zero's a try. I tried various taps and found that the X2 impedance multiplier sounds the best. My speakers are the Soliloquy's 5.3, which are an easy 8 ohm load, thus making it a 16 ohm load. This set up was sounding perfectly well, I thought, until I heard the Zero's. My preamp is a GG built from scratch and the BEl Canto Design DAC driven by a Sony 7700 DVD/CD player. After evaluating the Zero's I am not sending them back. Every aspect of the reproduction is enhanced, specially in the smoothness department. All the resolution,detail retrieval and dynamic aspects are kept but with much more refinement. The stage is also bigger. I don't really know if this is exactly as driving a 16 ohm speaker, but I am pretty sure it's very close. According to the designer, adding this device does not defeat the OTL's prime design purpose of not having an OPT, though this device works differently to an OPT."

Dennis Ketterer, OH LAMM ML-1 / A-S MA-1 and Cabasse Adriatis 600 Evolution Speakers (92dB, 4 ohm)
"The ZERO's are a tube amplifier's best friend regardless of which type. Unless you have 16 Ohm speakers I urge everyone to pick up a set of these puppies. They should be your next audio upgrade. If you can't afford them get them anyway. Use your upcoming $300.00 tax refund. Then you can thank two people for taking you to a higher audio level, Paul & George W."

"At the present time I'm running the 80W push/pull LAMM ML-1's. When the weather cools down at the end of summer I'll be switching over to the MA-1's. I have not as yet gone through all of the various taps to reach 16 Ohms. Paul's ZERO's have changed my listening habits from 2 - 4 Hrs to 8 - 10 Hrs per day on the weekends. As a result I did discovered my batteries for my Pre-Amp were bad. I was enjoying the experience going from 4 to 8 Ohms so much I just couldn't stop to switch taps. Moral of the story is I pity the fool who passes on the ZERO's."

"My speakers are the Cabasse Adriatis 600 Evolution's @ 4 Ohm, 92dB, 4 Way design. These speakers can actually be quad-amped. With only 2 of these speakers in the country no body really knows how they sound unless you heard them at 2000 CES which is the pair I have. Besides sounding fabulous they a high "WAF". They are the only speakers that she has actually invited her girlfriends over to see (of course not to hear). They integrate well in our decor. If you want to know more about them see North Star Leading The Way web site and /or their add in Absolute Sound issues #126, 127 or 128 with yours truly." Dennis

Bashir Ahmad, IL Atma-Sphere M-60 and QUAD 63 speakers
"My system consists of a Meridian 500 Transport feeding an EVS Millennium DAC 2 connected to a pair of M60 Mk1s. The speakers are Quad 63s mounted on Arcici stands; volume control is by way of a pair of EVS ultimate attenuators. All interconnects are Mapleshades. My impressions after a day and a half of living with Paul Speltz's ZEROs are quite positive. I should mention that upon initially connecting them I was tremendously disappointed by the sound I first heard. I was actually experiencing lowered resolution and (very surprisingly) a decrease in volume! I then noticed that I had connected the leads intended for the amplifiers to the speakers and vice versa; not entirely certain why that makes such a huge difference, but it does. Reversing the connections to the intended orientation resulted in an immediate improvement in the sound. I've experimented thus far with the 2x and 4x impedance multipliers; the former, in my case, is the preferred alternative.Relative to no ZEROs, the 2x configuration yields a number of noticeable changes. The most welcome was a tightening of the bass. I had some qualms about using the ZEROs with the Quads because Atma-spheres are apparently quite well suited to quads in the bass region; I had initially feared a worsening of the loose and near panel rattling bass I already had - quite the opposite as I've quickly learnt. The bass is somehow righter, tauter, more organic and controlled, and generally more representative of live music; best of all I get these benefits with no decrease in impact to speak of. From the particular perspective of a Quad 63 owner, the annoying bass vibration induced buzzing of the panel dust covers are significantly mitigated. My dust covers are quite loose at present from many months of playing, but they now intrude markedly less on the listening experience. I imagine , once tightened, they will not only be completely free of said vibration, but will presumably, require re tightening far less frequently. The second major difference was a significant decrease in distortion. Certain higher frequencies, female vocals in particular (Kendra Shank on Afterglow for example) induce far less of a wincing fit on my part when played at higher volumes - definitely easier on the ear. There is a rather small (not as obvious as the first two changes, but still there) increase in higher frequency resolution and inner detail; more air around performers and instruments; more of a three dimensional feel to the sound, and a slightly deeper soundstage. The reduction in distortion with its attendant decrease in a slight brightness/edginess to the sound, might initially lead one to suspect a loss in detail. This is, happily, not the case. I'm not sure if the ZERO's actually allow more of the information than before to pass through, or if its their affect on distortion that allows the detail already present to shine through. At any rate the desired effect is the same. The 4x configuration yields the somewhat dry/solid state sound that the accompanying literature forewarns. It sounds slightly artificial and rather less involving than 2x. I hace yet to try the intermediate setting (2.75x if memory serves me correctly). Altogether, the ZEROs are quite a pleasing product; they aren't terribly expensive and they work as advertised, even for Quads (about which I had my doubts). I suspect (though do not know for a fact) that a pair of ZEROs would precipitate an even larger difference on conventional dynamic driver speakers. At any rate, well done Paul. Cheers", Bashir.

David Kuipers, TX Everything (see below)
"..........I owned the M60s for over a year and a half, and sold them when I decided to go with some low impedance speakers for awhile (Thiels). But loved the amps, and after owning quite a few amps in the interim of a variety of topologies, I'm ready to come to back to A-S, they're still the best I've heard. Tried SETs and tube push-pull, solid-state MOSFETs and bipolars, even a couple of hybrids. So many amps sound artificial and hifi, they just leave me cold, but A-S never gave me that impression. The only issue with them ever was because of the OTL topology, speaker options are so dang limited (I owned Merlins and Meadowlarks with the M60s). Which makes the autoformers a great idea! Don't have to ditch the amps when an interesting but impedance-challenged pair of speakers comes along. Shoot, maybe I'll finally get the Maggie 3.6s I've wanted to get for so long.......... :-) Or I could run M60s with just a pair of 6AS7s and the autoformer and get those big Tannoy Churchills........"

Michael Anda, ND Atma-Sphere M-60 and N.E.A.R. 50Me II speakers (6.5 ohm min)
"Zero's took my system up to another league......I finally hooked up my Zero's yesterday and the results were incredible. I am using M60's to drive N.E.A.R. 50Me II speakers. These have a nominal 8 ohm load with a minimum impedance of 6.5 ohms. I am using the 2X leads directly from amps to speakers. Wow! is right. Paul stated that I would be smiling after installing the Zero's. I can't argue, but I have yet to make it past the Wow! stage. BTW, descriptions of the improvement have been scarce here on ASOG so I will give it a shot. With the Zero's in place a MAJOR blockage to the source material seems to have been removed. There is an "ease" to the presentation that probably has to be heard to be fully comprehended. Like upgrading from a lesser preamp to an Atma-Sphere, "more music" is now presented, both in quantity and quality. In any event, the Zero's have made listening to music more pleasurable. As Paul Speltz has stated elsewhere, the Zero's are a speaker "fix" and not an amplifier "fix". I am guessing that the majority of speakers in use by ASOG followers would benefit from the Zero's. Thank you Paul. Mark, thanks to you also for starting and maintaining this site. I wonder if the Zero's would have ever seen the light of day without ASOG. Blessings to all."

"I am using the Paul Speltz Zero's as my "speaker cable" right now and could not be happier."

Adam Berusch, CO Atma-Sphere amps and Martin Logan CLS IIz Speakers (1-4 ohm)
"After selling my SL Auras, I decided to try the ML CLS IIz speakers. I've always wanted to experience their sound and, being the type of audiophile who likes to try different things as a learning experience (even if the sound is disappointing), decided to take a chance without an in-home audition. I purchased the CLS's, used, in black oak (looks very nice in the mono color format). There was just one problem - whilst my Krell (sic) would handle these speakers without issue, my A-S amps are not going to like the 1-4 ohm impedance CLS's are known for. Hence, I decided to gamble on Paul Speltz's Zero product. Based on the assumption that the MA-1's generate most of their power in the 8-10 ohm range, I used the x2.75 tap off the Zero autoformers so that the speakers now look like a 3-11 ohm speaker. Before hooking them (Zeros) up, I biased the amps with the speakers directly, without the Zeros or music playing. I then connected the Zeros without using any speaker cables. The CLS has a platform over it's transformer, which is where you can conveniently place the Zeros. I had spade lugs permanently attached to the Zeros for the amp connections and used detachable banana plugs for the speaker combinations (speaker attachments can vary based on the settings you want)."

"THE SOUND: Incredible!!! Even after a very informal setup, the imaging, detail, transparency (etc) was really something. I had assumed that there would be little or no bass. Well, I gotta tell ya, the bass was very strong down to just under 40hz in my smallish room. I have extensive experience with Magnepan, Sound Lab, and Avantgarde, and this combo blows those others away! This is the kind of pleasant surprise audiophiles look forward to, but rarely get. I did not notice any anomalies in sound with the Zeros installed. I tested the sound using a variety of sources, including the XLO test disk and The Absolute! Sound space cd. The sound passed all the tests impressively. Granted, these are very initial impressions. But, I would strongly suggest that if you like very fast, precise, and detailed sound, I would definitely try the A-S / ML CLS combo. The Zero makes it work. Paul - You sir are a mad man! It's people like you that make this industry far more interesting. Job well done!" -Adam

Garland Branch, MA Atma-Sphere M-60 and Vandersteen 2ci (7 ohm) speakers
"The speakers have a relatively benign impedance curve @ nominally 7 ohms. The Zero's are on the doubling (2x) leads/ yellow and blue. The amps are the M-60 MKII's I built from kit and have not modded much other than adding a bit extra output capacitance and hexfreds in the driver power supply. Thanks to Paul Speltz, My Vandersteen 2ci's can finally come alive with the addition of the Zero's Autoformers. Initial listening reveals more open sound, presence and dynamics. Also, there seems to be a smoother high freq. response which is almost too smooth ie. recessed. I'll wait for full break-in for final judgement on that score. I've messed around with my preamp so it needs a good break-in as well. So far so good! Thanks again, Paul!" Garland

Ming Pan, PA Atma-Sphere M-60 and QUAD 898 speakers
"I have used MK60 and 989 for about a year and with zero for 3 months now. These are great combinations, period. Without zero, the sound was warm and rich not at all analytical as described in TAS (it may have something to with lower impedance at mid and highs). The only down side I could detect was I felt the speakers were somewhat underpowered. After getting encouragement from Greg at Washington, I got the Zeros. With zeros in, life gets significantly better. The overall sound becomes much more effect less with much improved mids and treble. The balance does shift with zeros in - depends on setting, higher setting has brighter sound. The balance shift depends on other components in the system, 2x works better with Benz ruby cart and 2.75X with Grado reference and radio shack CD-3400. These are my personal preferences, I can not say which is more "neutral". One added bonus, with zero in, I do not feel 989 is underpowered anymore (room size 30x15x10, dinnig+living rooms). Needless to say I am very happy with the combo especially with zeros in. I have no experience with MA-1 so can not make comparison. Other components in the mix are Audio Research CL30, Martin-Logan Arieus, passive pre amp or monarchy audio). Hope that helps."

Dave Derrick, PA Joule-Electra amplifier
"I'm using ZEROs with a Joule-Electra amp, and the combo has somewhat better resolution, especially low level. Upper end may be a bit more extended, without increased harshness. A touch more air as well. The degree of any given change is not dramatic, but the overall effect is positive."

Harry Straub, MN Atma-Sphere M-60 and Magnepan MG3.5 speakers (4 ohm)
"I have tried the Zeros with my Atma-Sphere M60 amps and MG3.5's, and own a pair of Atma-Sphere's original Z-Music Autoformers(the predecessor to the Zero's). I will not run my M60/MG3.5's without the autoformers, it makes an extremely large improvement. It is not subtle, it is not voodoo or magic, it plain and simple works. That is with my OTL's, which need them for 4ohm speakers.(Nothing new said here, but wanted to state my experiences.) I do own a Conrad Johnson amp(MF2500) as well, but have not tried it with the MG3.5s and autoformers. Frankly, I haven't because I don't think they need it. The CJ provides enough power into 4ohms(400 watts I think), that I have never screwed around with it. If anyone is really interested, I can hook them all up and give feedback. I personally think the best test would be with an underpowered amp(NAD, Adcom, DynaST70, or maybe a SE 300B amp) hooked up to the Zero's and Maggies. Could be interesting." Harry

I bet the CJ amp will sound better if its 8 ohm (or 16 if available) tap is used and the ZEROs are used to make the Maggies look like 16 ohms..........You should try it! Paul

Manuel Florensa, Italy Atma-Sphere M-60 and 8 ohm / 89dB Speakers
"Although I am technically unlearned, I certainly am a music lover and, ever since I heard the first note out of them (M-60s), I'm a devoted Atma-Sphere family member. As such, I want to congratulate you and to thank you sincerely for your commendable achievement. With your ZEROs in the chain, there is more, noticeably more of everything: more resolution and detail, more transparency, more speed, more width, depth and -- surprisingly -- height in the soundstage, much more of the so-hyped "palpability"... you name it. And the good thing about them is that they bring all this without any hint of edginess -- at least that I have so far been able to notice -- and, what's more important to me, without altering at all, the sonic signature of a given system (at least mine, with which I was already more than pleased and wouldn't have wanted changed). You see, when I got my Atma-Sphere gear, I thought I had finally brought music at home. Now, with your ZEROs, there's just more of it." Manuel

Will McGee, FL Transcedent Sound amps and Merlin speakers
"I just got the zero's on loan from Vinh-Vu set-up last night and can only say I was mightily impressed. I really didn't expect this degree of improvement in resolution especially in the bass. It was so palpable. Maybe the power limits of the amps were hiding this? Low level resolution is astounding, even with the Merlins which really excel in this area. I am using the 2.75 setting per Vinh's recommendation with Merlin/Transcendent combo. I will be playing around with other settings to find which one works best for me. Will keep you posted."

"Hi Paul, Just completed the boxes a few weeks ago and am listening in bliss with the zeros in the system. The added clarity (less distortion?) is welcome. I haven't decided on the final multiplier but am leaning more towards the 2x over the2.75x. In any event I will be posting my impressions on the Atma-Sphere site in the near future. Take Care, Will"

Mike Currie, Atma-Sphere S-30 amp and Quad ESL-63 speakers
"I guess I have been among the most skeptical in thinking that ZEROs would do nothing for my Quads given that speaker's impedance curve. I have purchased DK's pair, and though I've had them set up for only a couple of days now, it is apparent that I was quite mistaken. The most profound difference is in the mid and upper bass, which has both tightened up and has become more 'organic'. I never have figured out what the latter term really means in sound reproduction, but I guess you know it when you hear it. Deep cello and double bass simply sound more real - and they sounded pretty damn good to begin with. Two days do not a long term partner make, but I can say right now that unless some strange deleterious effects show up unexpectedly, this is the best 'tweak' money I've ever spent. Congratulations, Paul!" Mike

Wellfed, N.E.A.R. 50Me II speakers
"I am using N.E.A.R. 50Me II speakers with Paul's ZERO's and concur with Mike's results regarding more "organic" bass performance. All the drivers in my speakers are metal cones and in addition to deeper, richer bass I found a lessening of a "metal" sound on drums. While not applicable to those with planar speakers, such as Mike and Travis, further improvement resulting in more "organic" bass, can be had by applying Marigo Audio VTS Dynamic Driver Bands on the bass and midrange drivers of dynamic speakers. As I have mentioned before, every tweak or change to a system element seems to be extremely dramatic with the ZERO's in place. It is really rewarding to get such great performance with every investment, whether time or money."

David McCleskey TX SoundLab A-1s and Atma-Sphere MA-1s
"I have not been able to try the biwiring configuration yet, but I am convinced the ZEROs are a plus in my system. I am really enjoying every opportunity I get to listen to my system with the ZEROs. I am almost convinced that they are superior to the Transparent cables. I wanted to try another experiment, but I was not sure it is OK and I wanted to check with you. Can I drive the bass transformer of my A-1s with the 1.75X and the treble toroid with 2X or 2.75X at the same time? I find 2X to give me the best overall balance, but I like the effects of 2.75X on the mids and highs, but it overdamps the bass panels. I was thinking maybe I could get the best of both worlds if I can use two taps at the same time?"

Yes! The ZEROs can safely give you that flexibility. Try it and let me know how it goes. -Paul

"I wanted to touch base with you on the ZEROs. I finally got a chance to biwire my A-1s using the 1.37X tap for the bass transformer and the 2.75X for the mids / highs. I used a piece of Audio Research Litz to complete the negative leg for the 1.37X connection to the bass transformer. Given that I had heavily modified my backplates already, I decided to take it to the extreme and eliminate all mechanical connections. I removed the binding posts and took the wires from the ZEROs into the backplate through the holes left from the posts. I placed a grommet in each hole. All wiring is direct WBT silver soldered to the transformer and circuit board. Results are just absolutely incredible. All the bass power is now coupled with shimmering and delicate yet powerful mid and high frequencies. The overall dynamics are increased along with a top to bottom seamlessness that I am just beginning to appreciate. Depth of stage and shear immersion in the sound are now common on most CDs and SACDs. In an often overused phrase, I am literally hearing tiny details I had not heard before on favorite disks. Your ZEROs are an unequivocal bargain and I appreciate your willingness to share your discoveries with others. Thanks so much..........David"

Glynn Wilson, MI Atma-Sphere M-60 and Waveform Solo (8 ohm)
"Hi Paul - I received the Zeros today and got to do a little listening, starting at X2. My amps are Ralph's latest M60s with all his options except the Caddock resistors and speakers are Waveform Solo's, avg impedance of 8, min of 6. Actually, I bought the Zeros on a lark, not really expecting much since my speakers were not too unreasonable a load, but, boy, was I wrong! Immediately noticed that leading transients on guitars were MUCH clearer and extremely dynamic - it made me jump in surprise while playing standards I had heard many times before. Bass was tighter and lines were easier to follow and more coherent. There was a better sense of space - of a glow, if you will, around the instruments. I switched to X2.75 and this glow disappeared, so I immediately switched back to X2 so I could continue to revel in the sound. A while back a friend brought some Coincident speaker cables over and they made a similar improvement - makes me wonder if the Coincident designer is designing a similar effect (or perhaps achieving it accidentally) into his cables. Since I like to use long speaker cables (I have the Zeros at the speaker end of a 20' pair of Canare Star Quad cables), these offer a much less expensive alternative to long expensive cables that may or may not work well with my gear. I could not be more pleased. Put these things in a fancy wood box on tip-toes with a pretty cable sheath and sell them for $2K. Thanks."

Daan van Egmond, Holland Atma-Sphere M-60, Spendor BC2 and AudioStatic ES100
"I currently play with AudioStatic ES100 that a friend loaned me. Without the Zero's the sound seemed to be tilted backward. Tilted in my eyes, bass was there but dominant and not clear, the mids/highs were distant. The Zero's brought the balance back. Bass cleaner and more in proportion, and the mids and highs back again in the right place. Looked like the M-60 struggled with the load in the upper ranges. Suspect adding some extra 6AS7 tubes will have a similar effect. Maybe nice for in the Winter when it is cold. This seems to work fine and is much simpler. My system is still in flux. Sony SCD-777ES , Modified Dynaco PAS-3x ( Joe Curcio mod FET- ECC802S) , M-60 MK II.2 and Audiostatic ES100 electrostatic loudspeakers. Building a balanced preamp and am eager to find how that will sound compared to the single ended configuration I use at the moment." Best regards, Daan

Gary Susott, KS Cary V12 (Push-Pull) amplifier and Magenpan 1.6 speakers (4 ohms)
"Paul, Just thought I would let you know the ZEROs arrived yesterday and I'm a happy customer. I didn't have much time to experiment or listen last night, but the initial results were very impressive. I set up my amp and the ZEROs to double the damping factor because the Cary amp has a high output impedance, a little more than half the tap value, I understand. A whole new world of bass clarity appeared. This was not at all subtle. I was hearing surprising bass depth, space, air, and delineation I never heard before. The overall listening experience was quite improved. I'll have more time to experiment over the weekend. It's been a pleasure."

Stew Glick, NY Wright/Sound 3.5 2A3 SET amps, driving Quad ESL63 speakers
"Paul, I received the zeros, thanks! I put them into my system and even though they are not even broken in yet, I heard an immediate improvement in my stereo. I used the 4x setting on my Wright/Sound 3.5 2A3 amps, driving Quad ESL63 speakers. The bass is deep and VERY tight, plucked strings have more of a percussive sound, and the sound is cleaned up overall....it really makes me shake my head in disbelief that I am getting this kind of sound out of a pair of 3-8 watt 2A3 amps. (I do also use a Hsu VTF-2 sub, but any changes I am hearing is coming from the speakers as the sub is driven via the preamp outputs). At this time I have no desire to check out other settings, as 4x is pretty high and I am not hearing any thinness or the like. I feel like I am getting the most out of the zeros with no negative effects as they are set up now. Thanks for you help and friendly assistance." Stew

"I'm still very impressed with the sound of my stereo since adding the zeros into the equation. Everything sounds so natural, effortless, organic. Thanks for your help." Stew Glick

Travis's additional comets
"Not only did it make the amps work easier, it sounded better, more detail, clearer picture (Mag 3.6) and I don't have to spend money on snake oil speaker cables. Already I'm saving money."

Harry's additional comets
"I have a set of autoformers, and have tried Paul's Zeros on my 3.5rs. They work as advertised. Anyone who is using a low power (under 50wpc) on their Magnepans will get better bass and fuller sound. It is not subtle, it is not like using new cables, it is like getting a more powerful amp. I read a lot of posts saying ST70, MKIII's and other lower powered tube amps work great on Maggies. I have used them, and they saturate. They don't provide enough power into the 4ohm load to drive them fully. Zero's will make them work beautifully, you WILL get better bass out of maggies. I don't work with Paul, but I do know him. He has made a great product, and he is not charging enough for them." Harry

Mike Currie's additional coments
"Paul, Nice site. Your sister did a fine job. The more I listen to the system with the ZEROS in, the more I like them. Please note that this applies to my new M-60s just as much as my former S-30 (which is listed as my amp under 'Testimonials'). This is a great product and a true bargain."

Chung-Tao Chang, CA Cary 300SE signature to drive B&W Nautilus 805.
"I received them this afternoon. Initial impression was more musical & dynamic. After breaking it in some, I found it has more low-frequency weight & body, and less high-frequency extension & delicacy. "

I asked Chung-Tao to, "connect your Cary amp to the YELLOW (+) and BLUE (-) leads. Connect your B&W speakers to the WHITE (+) and BLACK (-) leads. This will give you a 2x multiplication factor, but using less windings for a slightly faster and more transparent autoformer." Chang reported better sound this way. NOTE: Chung ran the long leaded version (6' total span) of the original ZEROs which sound their best when the leads were considerably shortened. The ZEROs now have Teflon insulated Silver coated copper leads that remain transparent even with long leads. Paul

Sang Oh, MD Jolida 50 watt (Push-Pull) tube amp & 8 ohm JM Lab speakers (8 ohm)
"Dear Paul, I demo'd the ZEROs for my friend, Andy Timmonds. Bad move. He refuses to part with them and is begging me to sell him my set. I am going to accommodate him if you can send me another pair in the near future. I believe the amount of the last pair was $383 shipped. Do you have any left. I can send you a check ASAP. Thanks." "I currently have a Jolida 50 watt push-pull tube amp driving 8 ohm JM Lab speakers. I bought the ZEROs in preparation for my eventual system, which will most likely be Atma-sphere MA-1's and Magnepan 3.6's. I bought the ZERO's now because I knew they would help out my current setup as well as my future setup. As predicted, the presentation of my current setup became much more refined at the 2.75 X level. Vocals sweetened and lows (especially in the kick drum frequency) tightened up tremendously. The soundstage became wider and more laid-back. The difference was pretty startling. CD's that used to expose my current system's weaknesses actually became palatable. Basically, the ZERO's allowed me to live with my current system for a bit longer." "Andy, on the other hand, has his system, almost complete. Joule Electra VZN 80 driving a pair of Magnepan 12's. He didn't know it, but his VZN was huffing and puffing. I heard it clip a couple of times and things like tympanis and the overall presentation was greatly disjointed. Once again, at the setting of 2.75 X, things really took shape. Overall presentation was layered to a degree that was really magical. Midrange is so sweet and palpable. Tympanis and kick drums sound refined and integrate with the overall presentation beautifully. His sound is a little too laid back for my taste, but I like it a little bit more in my face. His next step is to monoblock with the 3.6's. You can bet the ZERO's will survive that transition." "I guess the ringing endorsement from my experience is that the ZERO's can help your system, period. It doesn't matter whether you have the latest OTL's or a $500 push-pull. There's no doubt in our minds that tweaking the impedance on a speaker will enable you to improve your sound. Paul, there should be a lot more people buying these from you." Thanks, Sang Oh

Michael Anda, ND Reports on using two pairs as a "Bi-ZEROs" configuration
"Hi Paul, You are right, this is fun. I forgot to mention a few things regarding my use of the ZERO's. I told you about the added detail and smoother (less harsh) sound achieved with the alternate 2X single ZERO configuration. What I neglected to mention was the marked improvement in image specifity with this setup. In the bi-ZERO configuration this prized quality was even more apparent, more thrilling than this though, was the newly manifest soundstage depth (one of the deficiencies of my system). And then, on top of all this, more detail. I was listening to a CD last night on which I had never took notice of any female vocal accompaniment, with the bi-ZERO's not only was the female backup vocalist present, but was also a prominent element within the music. I still feel the need to listen to a lot more music before posting results to the ASOG site, plus the bass ZERO's only have 1.5 hours on them. My setup seems to be so sensitive to system changes, teetering on the edge of harshness in the high frequencies, that many times any given upgrade has the potential to make some recordings sound better and others worse. So far though, I am wildly enthusiastic about what I am hearing with bi-ZERO setup. It just seems that my whole system has again improved by leaps and bounds, and I am having a little bit of a difficult time believing my ears, which is stupid. To summarize, I really like what I hear, a lot. One more thing I suspect, but haven't verified (due to lack of quality listening time), is significantly improved resolution. I get this feeling that subtle, but profoundly important things are occurring. This is deep isn't it. I've got it bad? I would really like to hear your results going from 1 to 2 pairs. Do you ever come to, or drive through, Fargo, ND? If you do please drop in and see what you think."

For me the bi-ZEROs added an increased sense of transient speed. Rising edges sounded faster. Dynamics increased. The music gained more life, more jump. I like it. Paul

Paul Speltz, yes, just me. SONY DA30ES (Solid State) receiver, and my DIY speakers (4 ohm)
I wanted to see what the ZEROs would do for my system if I plunked in a solid state amplifier, so I pulled my SONY ES Series receiver out of the theater room, and brought it up into the music room. I gave this set up two weeks of listening so I would be confident with my findings. To keep it simple, I only compared a direct connection from amp to speakers, against using the ZEROs 4x multiplication factor to make the 4 ohm speakers look like 16 ohms. When I removed the ZEROs the sound of the highs got spitty and became disconnected from the rest of the music. When I put the ZEROs back in place, the music became more punchy, smooth, open, fun, and natural. When I pulled the ZEROs back out, the music got spitty again and there was a slight harshness or hardness that made me feel like I wanted to turn the music volume down.

By coincidence, last night I was looking through the March 2002 issue of AudioXpress and came across an article by Douglas Self about distortion in bipolar solid state amplifiers. Mr. Self has written several books on the subject of distortion in power amplifiers, and has a web site: www.dself.demon.co.uk Anyway, the first two sentences in this article are, "Audio power amplifiers always-without exception-give more distortion with heavier loading. The lower the load impedance, the worse the non-linearity." The article includes 4 different distortion graphs each comparing distortion levels with different loads (4, 8, 16 ohms, etc). In all cases the distortion became less as the impedance increased. I can't help but think that this explains why the music sounded better when the ZEROs were added to make my 4 ohm speakers feel like 16 ohms to the amplifier.

Jose M. Rodriguez, PR Naim M1.1 (Solid State) amplifier and Parsifal speakers (8 ohm)
"Hi Paul, Had heard a bit about the zeros, but a couple of days ago got a pair on loan and tried them in my system. WOW, never had anything brought so much improvement to it. Work best with 2x setting. Do you have Zeros available? Thanks." Regards, Jose

Greg Gresham, SC Rogue 88 (Push-Pull 6550s) and Itersound Isis electrostat speakers (4 ohm)
"Paul, I just wanted to get back with you on the Zero`s in my setup, they worked GREAT, they sound there best in the 2.75x tap. I could not believe how much better this system is with the Zero`s, you hear all the music that seemed to get lost in the mix before , I have e-mailed a few people on the web site Audiogon and told them about this product, well done Paul well done." Greg

Michael Anda, ND Additional Comments
"I have been using ZERO autoformers for approximately 9 months now and am extremely happy with the results. Better bass, lower distortion, and more life were added by the addition of the ZEROs. On the whole my system sounded less fatiguing as well. On occasion the sound was somewhat 'edgy' in the high frequencies, but I lived with this as the benefits of the ZEROs outweighed this negative by a large margin. A while back, Luis, an ASOG contributor, pointed out an alternative 2X wiring configuration. This cured the 'edginess' resulting in smoother, laid back, sound. Detail increased slightly but perceptibly. It also improved imaging noticeably. One drawback was a slight reduction in bass output. Again, the plusses greatly outweighed the minuses. I probably would have been happy with this configuration for a long time had I not tried the bi-ZERO configuration. In my system (tweaked N.E.A.R. 50Me II loudspeakers/AS M-60 II.2 amps) using the alternative 2X ZERO configuration on the high frequencies and the standard 2X configuration on the low frequencies, everything seemed to gel. The whole seemed vastly greater than the sum of the parts. For the first time I had more than just a hint of soundstage depth. The whole presentation became more credible in just about every area except image height. The sustained decay of instruments was one notable sign of the increased resolution. Increased detail is apparent from the low end of the frequency spectrum to the top. Musical nuance abounds. Background vocals become a more prominent part of the music, separation of the various components improved significantly. The music has more texture. So radical is the improvement that many times it seems like you are listening to a different piece of music. One of the really cool things about a great upgrade is having music that previously didn't do much for you now become more interesting and occasionally eclipse previous favorites on the same disc. This has happened numerous times in a week and a half of use. I hope someone out there will try this and report their results. This upgrade has been, by far, the most revolutionary improvement to my system ever. One note, I am also using Walker Audio High Definition Links Mk. II on all speaker connections and I believe these are partially responsible for the great sound I am getting with the bi-ZERO setup. Another thing, I strongly believe that ZEROs and bi-ZEROs really help maximize ones investment in sound equipment and accessories if the speakers in the system are candidates for ZERO use. The N.E.A.R. 50Me II has nominal impedance rating of 8 ohms and does not dip below 6.5 ohms impedance according to the manufacturer."

Quoc Nguyenngoc, NJ Futterman H3 OTL amp w/ NHT (4 ohm) and Klipsch Cornwall (8 ohm)
"I received the Zeros on Monday. Even though I had to fly out early Tuesday, I just had to hook them up. Wow, what an improvement! I will try to write a review for that later, as to how they sound on the Cornwalls and with the Fourier." Quoc "The Zeros represent a significant tweak in the quest to get better stereo sound. I tested the Zeros on my 1976 Conrwalls and two of my amps, one is an OTL by now defunct Fourier Components and the other an SET amp by Wright Sound. The OTL amp is the Panthere monoblock with 8 russian 6c33c MIG tubes in each amp. The SET amp is the Wrigth WPA3.5 with Sovtek 2A3s. The WPA3.5 has been reviewed extensively in some other forums. The Cornwall has a rated nominal impedance of 8 ohms, but according to the Belgian Audio Society test, it is more like 6 ohms nominal, with a dip to 5 ohms around 100hz. With the Zeros connected directly between the amps and the Cornwalls, the sound is much much cleaner, with strong and very tight bass, the highs are sweeter and resolution jumps up a notch. I found the 2.75X setting better overall than 2X. Surprisingly, the improvements are much more significant with the WPA3.5 than those on the OTL Panthere, especially in the transparency, layering and quickness. I found the WPA3.5 better when its output impedance is set at 8 ohms than when it is at 16 ohms. At the higher settings, clearly the mid and highs start to sound dry. Without the Zeros, I rated the Panthere slightly better than the WPA3.5 on the Cornwalls. With the Zeros in, I found the WPA3.5 better than the Panthere. There is a better feeling of "you are there". The Panthere is the sweeter amp and its mids and highs may be a bit too sweet. As tweaks go, at less than $400, the Zeros are a steal." Quoc Nguyen, NJ

Rutton Ruttonsha, Netherlands DIY M-60 and B&W Nautilus 802 speakers
"I have now been listening to my stuff with the zeros for about six hours now and find that the change in sound is very noticeable. Nothing subtle about it. This is no "Tweak"! This is a major change!!! I have them between a DIY m60 (with 16 output tubes instead of the 8, and i re-did the drive circuit incorporating the Allen Wright SLCF (solid state) and using his super regs for the driver power supply.) and B&W Nautilus 802's. Since the speakers allow bi-wiring, i am using the 2x for the mid and highs, and the 4x for the Bass. The biggest positive is an extremely large soundstage. Quite remarkable really. Something i must say i have never experienced before! I expected a bigger improvement in bass response, but really the highs became really prominent. What seems to have suffered a little are the mids. As a result, the amps seem to have lost their smoothness and relaxed nature. My wife noticed the difference and commented that the music sounded "Nervous". Bit of a strange comment, but really quite accurate. Not sure if I just have to get used to the new sound or if the sound will settle down after an extended listening period. I am not sure what effect lowering the ""X" factor on the mids/high will have. You obviously have a lot more experience with this so your advice is appreciated! Obviously I do not want to loose the soundstage................ Great job Paul.. Best Regards, Rutton

I found the solid state SLCF circuit to sound "Nervous". I actually described it a year ago as "overly excited", which is the same as nervous. I think that the ZEROs allow you to hear this better. Many people describe that the ZEROs allow them to hear all small changes in the system, showing off what the system really sounds like. I am much happier with the all tube SLCF. The nervousness goes away, yet even more top end speed and transparency are achieved. If you want to bi-wire, may I suggest that you use the same multiplication factor for both the bass as the mid/highs. You will notice that 2.75x is available in two positions. Wire the WHITE (+) and BLUE (-) to the bass, and wire the YELLOW (+) and BLACK (-) to the mid/highs. This will keep the same voltage sensitivity between the two. http://www.otlamp.com/tweaks/ps/zero/group1.jpg Using the Group 2 configuration, you will find two pairs of 2x. You should try this as well. GREEN (+) and BROWN (-) to bass, and WHITE (+) and BLACK (-) to the mid/highs. http://www.otlamp.com/tweaks/ps/zero/group2.jpg Let me know what works best. Enjoy, Paul

Steve Sun, MA Transcendent Sound T-16 amp and Quad 989 speakers
"I like to report that the ZEROs work very well with T-16 and my Quad! Now, they are about 100 hours, and they start to sound really really good. I am using ZEROs for 2x the impedance, and will try other taps when I have chance. Of course, I will tell you more about my experiment... At least, so far, the ZEROs are working better than ANY speaker cables (I connect my Quad from T-16 thru ZEROs only). Thanks a lot." Steve Sun

Sherif Elkady, Egypt Cary CAD-50 monoblocks and KEF 105.3 speakers (4 ohms)
"Hi Paul, Received the Zeros this morning. Wow Paul ! They resemble the power supply trannies of my ex-Plinius Amp !! I tried briefly the 2x and 4x settings with my speakers (4 Ohms) this afternoon. Can't make up my mind yet but the 2x looks more suitable. I'll try other settings and let the ZEROs break-in for a few days. No sonic signature detected so far and the sound is now more fluid like water, less harshness, more details showing up etc.. Thanks very much Paul. I'll let you know as I go along." Best Regards Sherif

Norbert Christmann, Canada Carver M-500t (350 watt Solid State Amplifier) and Magnepan 2.5r speakers (4 ohms)
"I have come across a "Tweak" that really deserves to be mentioned, Paul Speltz's Zeros or impedance matching autoformers. The autoformer generally makes your amplifier run at its optimal impedance regardless of what the speakers impedance is. The results are something that is to be desired. I was a skeptic, really I was, and now I think everybody should own a pair of Zeros. More information on the zeros can be had atPauls Zero site: http://www.otlamp.com/tweaks/ps/zero/index.html It is not just myself and a hand full of others who know about these things if you follow the link below you will find that McIntosh (the amplifier manufacturer) encorperated impedance matching autoformers into many of thier high end amplifiers. http://www.sundial.net/~rogerr/mcintosh1.htm#autoformer At any rate perhaps the review that I sent to Paul will help you understand. Hello Paul, Well I'd say I owe you a review Paul. System Setup: Carver M-500t Magnetic field Amplifier, Carver C1 Preamp, Carver TL3100 CD player with upgraded DTL, dbx 1215 Dual channel Equalizer, Systemdek IIX turntable, Diy Kimber TC4 biwire, Magnepan 2.5r speakers, diy silver interconnects and of course the Zeros. When I initially visited the ASOG site I was some what lackadaisical about all the tweaks that I have tried. Still in search of the magic that my system seemed to have lost. I couldn't put my finger on it but the music just didn't excite me anymore. As you can see I tried a couple of different things, However the changes in the interconnects and the speaker cable did little to seriously improve the sound of the system it seemed labored and somewhat blended, a lack of distinctness in the separate instruments, Not that they were not present they were but seemed to some how blend.particularly the mids this was especially true once I moved to the Magnepan. At any rate I read what was present on the ASOG, and Paul's Site. At first I was somewhat skeptical, I thought "great, yet another money sucking tweak that will provide me with small or barely discernable gains". In fact owning a solid state amplifier I was concerned that these may not work at all. After much Vacillation I contacted Paul and ordered a pair of Zeros. Even after I ordered the zeros I continued to wonder weather I had wasted my money, to the point that I was dilly dallying around getting the money off to Paul (Sorry Paul). Then one day about a month after I had ordered them I received a phone call from Paul wondering whether the money had been sent, or if it had been lost in the mail... at any rate I finally got the money sent away and received the zeros shortly thereafter. The Magnepan 2.5r's are a 5 Ohm impedance speaker known to have impedance dips down to 1 to 2 ohms. The Carver M500t is rated @ 350 watts per channel into 4ohms and 250 watts into 8 ohms. I really believed that the amplifier would drive these speakers. I reluctantly hooked the zeros up at the 4x setting (making the Magnepan a 20 ohm load with dips presumably down to 5 or 6 ohms). The difference in the sound is nothing short of phenomenal. The bass tightened up considerably, lack of distinctness that annoying blend disappeared, in short the zero's added much needed definition to the system through out the frequencies everything became more distinct individual instruments were easy to pick out an seemed to be reproduced better than I have ever heard my system perform. In retrospect I cannot believe how wrong I was about the zeros, they do work as claimed, and far exceeded my expectations. The moral of the story is simply this: No matter how big your amplifier (or how big you perceive it to be) it can always benefit from having things made easier on it. The difference has been quite welcome, thanks Paul for every thing. If anybody out there is wondering weather the zeros make a difference on a solid state amplifier, the answer is yes the benefits are well worth the price. Regards Norbert Christmann .I could invest in a new amplifier.. and have even considered doing so.. yet judging from the differences I have heard using the zeros I can safely tell you that even if I were to invest in that Mark Levinson or Krell amp there is no doubt that I would place the zero's behind them as well. By the bye I have also placed the zeros on a Marantz sr8100 receiver and taken note of an improvement there, while the amp was driving a pair of energy pro 22's."

Phil Jolette, MI Rogue Magnum 120 amp (Push-Pull 4 x 6550 tubes per side) and Maggie 1.6 speakers (4 ohm)
"I am interested in trying the Zero's with my Maggie 1.6 and Rogue Magnum 120 amp (4 x 6550 tubes per side). Right now they seem lifeless and rolled off on top and the bass is flabby. They also seem to have very limited dynamics. I have read the testimonials on your website and it seems promising." "I got the Zeros today. My initial impressions are good. There seems to be a natural tone, when sitting at my computer and listening casually, I am reminded of the instruments more often than before. The bass seems more robust as well with more definition. I am using the 2X configuration and have only listened for about 1 hour, so they are not broken in. I will give more detailed account in about a few weeks. Thank you."."I have found the 2.75x and 4x settings sound best. Really tightens up the bass. Sounds way better than the Nordost Blue Heaven cables." Phil

Matt Roszkowski, MN Atma-Sphere M-60 amplifiers and Medowlark Heron i speakers (8 ohm)
"Yes, same system, shortened the leads, still didn't make boxes, though. Run them after Zu cable Wax cables into the Heron i's. Have noted increased bass, soundstage and extended highs."

Steven Michelson, CA Graaf GM-20 OTL and Alon IV speakers (3 ohm)
"Paul - Well, I am convinced that your zeros saved my system. After investing lots of $, it now actually reproduces music the way I had hoped. The match with my Graaf GM-20 OTL and Alon IVs (input impedance is around 3 ohms) is great! The improvement (openness, soundstage, clarity, bass) was obvious right off the bat and has improved nicely with time. BTW, my recent switch to the Placette passive preamp was also a wonderful and cost effective improvement. Thanks again." Steve

Mike Breneman, CA Transcendent Sound T8 monoblocks and Galo Solo speakers (4 ohm)
"Hi Paul, I received the ZEROs a little over a week ago. I haven't had much time to play with them yet as I was out of town for my son's graduation from college in Omaha, Neb. One thing is for sure, they will stay in my system! Best tweak for the dollars I have incorporated into my system yet. I am still tweaking for the best results. I will drop you an Email with a more complete report once they complete break-in and when I have settled upon a configuration." Thanks, Mike

David Wilkerson, KY Zen Triode amp (2 ohm OPT) and 8 ohm horn speakers
"Hi Paul, Just got the Zeros today and hooked them up. After 2 hours they sound pretty darn good. I will e-mail a better report when I put some real time on them. The 2.75 option seems to work well (2.9 ohm)." David

"Everything sounds very nice with the Zeros in the system. After 40-50 hours, the whole presentation seems solid and rich. The overall effect is most pleasing on recordings that show off harmonic content (Paul Simon's latest CD). I know I am not listening to music any louder, but the dynamic range is greater than before. My speakers are from the Horn Shoppe (8 ohm) and my amp is the Zen Select (about 3 watts). I started with the 2.75 factor (2.9 ohm speaker) and soon moved to the 4x( 2 ohm speaker). I may try other options, but so far I have been happy with the bass performance on the 4x setting due to the fact that my Zen amp delivers the most power into a 2 ohm load! Thank you for a great product." David Wilkerson

FYI: David is running the ZEROs "backwards" to best match his 2 ohm output transformer's impedance.

Chris Ossanna, (Audio Research's Field Service Manager) ARC VTM-200 and Magnepan MG10 Speakers (4 ohm) http://www.audioresearch.com/VTM200.html
I loaned a pair of ZEROs to my friend Chris, and after running them over the weekend he called me to report that the ZEROs "Made a substantial sonic improvement", and in the same breath said, "I'll send you a check". Chris knows that the 8 ohm tap on the 200 watt monoblocks sounds better than the 4 ohm tap (which is needed to drive the 4 ohm Maggies). We figured that the ZEROs are simply transparent enough to get the benefits of the better sounding 8 ohm tap. Since then, Chris has taken the ZEROs into ARC and set them up in one of their listening rooms. I understand that one of the Audio Research engineers wants to talk to me about them. I think he liked them too.

Jim Long (Director of Strategic Projects, Electro-Voice), MI Bel Canto eVo Amp & EV horns
"As to the sound, you may recall that I have a triamped three-way stereo setup powered by a Bel Canto Design eVo 200.6 six-channel power amp that delivers 120 W per channel into 8 ohms. Instead of looking for a good way to mate, say, a 4-ohm speaker to a tube amp that would provide better performance into a higher impedance like 16 ohms, I was looking for a 10-dB-or-so attenuation of the two HF channels which drive 110-dB (1 W/1 m) compression driver/horn combos above 500 Hz. I wanted the attenuation to drive down any amp or upstream digital processing noise revealed by the very high sensitivity of the horn and driver. (Of course, I can waste the eVo's power in the HF because 120 W is fairly high to start with and the horn/driver combo is of extremely high sensitivity.) I first duplicated the 9-dB or so resistive pad we used at the Pavec horn-system demo. This got the noise level low and sounded fine. The pad was a 5-ohm resistor in series with the parallel combination of a 4-ohm resistor and the nominally 8-ohm driver. I was concerned about the driver not seeing the low output impedance of the eVo amp. Passive crossover networks in speaker systems using HF compression drivers in conjunction with woofers of lower sensitivity generally provide some decoupling of the HF, as part of padding down the HF output to match the less sensitive LF device. But I wanted to avoid that. The eVo likes to see a low impedance in order to function properly, so I couldn't only connect the ZERO in, say, its 8-times impedance mode. (I tried, and it both sounded very bad and showed a rising high-frequency response.) So I loaded each HF channel with 10 ohms (handy power resistors I had around) and put them in parallel with a ZERO in its 8-times mode, loaded in turn with the 8-ohm TAD TD-2001 drivers currently in my system. That gives me an attenuation essentially the same as I had with the resistive pad yet the driver sees the low output impedance of the power amp. I listened at some length with the LF horns and subs muted, to a compilation CD I made (direct digital copies to my HHB CDR-850 stand-alone CD recorder) of favorite vocal tracks. I mono summed the stereo outputs and switched between left and right channels, with the resistive pad on the left and the ZERO-resistor combination on the right. (Previously, I checked both the listening-position frequency response and sound quality of both channels with the resistive pad and found them to sound pretty much the same.) My notes say that words on the ZERO channel are "easier to understand" and "more clear" than the resistive pad channel. Finally, I installed a ZERO on the left channel too. Both channels sounded equally clear. This is a fairly subtle effect but enough that I am happy to have the ZERO's in my system! Thanks for your neat product!" Jim Long

Phil Starr, IL Atma-Sphere MA1mkII amps and Carver Amazing Platinum IV spks (4 ohm)
"Hello, Paul, Several months ago, I purchased a pair of Zeros from you. I own a pair of MA1 MkII amps, with the blue and yellow leads attached, and a pair of Carver Amazing Platinum IV speakers. The installation of the Zeros gave additional "body" to instruments and voices. The installation created more detail in general, particularly in backup vocals and instrumentals. I was using a pair of Nordost SPM speaker cables in comparison."

Tim Kirkpatrick, GA Atma-Sphere MA-1 Mk II.2s and Spendors speakers (8 ohm)
"Well, Paul, I was skeptical. I really wasn't sure that the ZEROs would improve my nominally 8 Ohm speakers. Boy, was I wrong! I'm using the 2X tap to make the MA-1s think they are driving 16 ohm speakers. The ZEROs are everything you advertised them to be--tighter more defined bass, improved mid-range detail, and extended highs. All in all, the ZEROs just provide a much more realistic reproduction of the recorded event. I am a thoroughly satisfied customer, and I will pass the good word along. Thanks again for a great product! By the way, the ZEROs in the cherry case match my Spendors perfectly and actually look to be part of the original speaker system, and the cables you terminated for me work great. I'll try to send you some digital photos in the next week or so. Take care!" TK

Denis Byrne, NY Atma-Sphere M-60 amps and 96dB efficient speakers (6 ohm)
"Zero's are worth every penny, I am very glad I purchased them from you. A question for you: The amps are very efficient room heaters! My AC system is starting to do overtime. I have heard that one does not have to use the full 8 output tubes. Do you know if this is true? My speakers are 96db for 1 watt, and I am not asking the Mk60's to do signals below 100 Hz, I need only 16 watts to get 108db( which is louder than I ever use and will blow me out of my room) ,and so I am wondering if I were to remove 2 output tubes from each bank of 4 reducing the number of output tubes to 4 per amp( 2 for each bank) will the amps still work. I know that I would have to re-balance and re-bias to 300 mA ( 75x4=300). I am sorry to bother you, but you are very experienced in the use the M-60's. I just recently put the amps up for sale, but I have changed my mind since the tubes have run in. Look forward to hearing from you when it is convenient for you." Denis

Denis, No bother at all. Actually where you heard this was probably from me. Below is what is printed in the ZEROs White Papers: "After you have found how best to utilize the ZEROs for your system, you can now effectively change the number of output tubes without affecting the optimum impedance relationship (and optimum sound) that you have established. For example if you have found that you get the best sound using the ZEROs as a 2x impedance multiplier, then you can try removing half of the output tubes, but compensate for it by using the ZEROs as a 4x impedance multiplier, so that half as many tubes are presented with half as difficult of load to drive. The system should sound about the same but will play at 3dB less volume." Cut from: http://www.otlamp.com/tweaks/ps/zero/multiplier.html

This is exactly what I do in the summer time. I run only 2 ea 6336 tubes (equal to 4 ea 6AS7 tubes) and I also back down the bias down to 300mA. This along with using my ZEROs at a 4x setting give me all the power I need and even sounds better than a fully loaded amp. I don't recommend that you use a ZEROS setting higher that 4x, since the ZEROs become less transparent above 4x (ie 8x sounds compressed), but I do think you should run the ZEROs at 4x and run 4 tubes at 300mA for a while , and also try 2ea 6AS7 tubes at 150mA. Good luck, and keep me informed. Paul