| *AI Comments on Stereophile
Review For owners of Modulus 3 and early-model M3A preamplifiers we recommend that you carefully read this review. Mr. Fremer is a respected audio critic and we appreciate the fact that he invested a considerable amount of effort in producing this comprehensive and informative review. His comparison of the M3 and our M3A is absolutely excellent. Also, his constructive criticism and advice contributed greatly to the continued refinement of our M3A preamplifier.
Equipment Reports -
Stereophile Magazine Audible
Illusions Modulus 3A Preamplifier Audible Illusions Modulus 3A phono/line-stage preamplifier. Phono section gain: 28dB at I kHz (MM), 55 dB (MC). Maximum line section gain: 30dB. Output impedance: 1.2k ohms (main), 15O ohms (tape). Input impedance: 47k ohms. Frequency response: 2Hz-100 kHz within 1dB, measured with a 1:1 probe/100k ohm load tape in/main out. Phono section RIAA error: 20Hz-2OkHz : ±.25dB. Distortion: 0.02% (MC phono section); 0.015% at 20Hz (MM phono section); 0.15% at 1.5V RMS out, 20Hz-2OkHz into 50k ohms, 0.12% at 5OOmV RMS out, 20Hz-2OkHz, into IHF load (high-level section). S/N ratio: 74dB ref.5mV wideband input (MM phono section); 85dB ref.1.5V RMS wideband input (high-level section). Dimensions: 17" W by 3" H by 10" D (preamplifier); 5"W by 3.5" H by 10" D (power supply). Serial number of unit reviewed: M3950215. Warranty: 2 years parts and labor. Price: $1895 with MM stage; add $500 for High-Gain MC Gold Phono Stage; add $70 for gold or silver faceplate. Tube set (4) replacement cost: Grade A, $60 set; Grade AA, $100 set. Approximate number of dealers: 64. Manufacturer: Audible Illusions, P.O. Box 8, Pleasanton, CA 94566. Tel: (925) 463-2380. Fax: (925) 463-8482.
Run a set of interconnects from the EAD's analog outputs to an amplifier and you're rocking. Who needs a preamplifier, with its noise-inducing circuitry and analog-domain potentiometers? Anyone with other analog sources like tape decks, tuners or ...turntables. That’s who. That’s me. Hopefully you. While digital products from PS Audio (the Reference Link), Wadia (the Model 17), and Meridian (the 607) contain A/D converters which enable them to input analog signals, "digital vinyl" is to my mind and ears an oxymoron, the impassioned arguments of the Wadia folks notwithstanding. I've auditioned the PS Audio product and found it less than transparent in A/D mode, and subject to overload. Wadia claims transparency for its converter. Dare I believe? No.
When I got started in the reviewing business, I owned a heavily modified Hafler DH-101 preamp that I’d upgraded after reading Walt Jung and Richard Marsh's ground breaking capacitor article published in Audio some 15 years ago. I replaced and "bypassed" every capacitor in the box with polystyrene and Teflon versions— some the size of small sausages. I replaced the hookup wire with what AudioQuest was making at the time, and the input and output jacks with gold-plated Teflon-dielectric Tiffany connectors that were mounted to the preamplifier’s top cover— the only place they'd fit. The chassis literally groaned under the weight of all the caps I'd wedged in there. The improvement in sound was amazing, but to me there's nothing more annoying than reading a product review in which a "home-brew" component is part of the reviewing chain. I needed a preamplifier readers could relate to, and besides, the Hafler couldn’t take a low-output moving-coil cartridge straight in, so out it went. The next logical step up for me and my budget was PS Audio. I owned a succession of their preamplifiers — 4.5, 5.0, 5.5 — all of which had many fine qualities like low-noise moving-coil sections, outstanding sound staging, impressive image specificity, but some serious shortcomings, such as threadbare midrange, chilliness on top, and a fondness for amplifying RF. Neutral-sounding, you say? No way. Colorations? Clearly. Colorations I had to work around in reviewing other components. Still, the PS Audios were nice pieces for the money. Eventually I moved on to Rowland’s two-box Coherence One. This solid-state preamplifier was far more fleshed out in the midband, but somewhat closed-in on top and a bit fat on the bottom. It also cost over twice as much as the most expensive PS product —reflected in its build quality— but I still wasn’t satisfied, especially once the EAD 9000 arrived and I could compare the sound of CDs directly out and through the preamplifier. The last preamplifier I had in-house before leaving The Absolute Sound last year was Jadis's "budget-line" DPL line-stage/DPMC phono preamplifier combo— a mere trifle at $8600/pair. The all-tubed-units looked and felt sumptuous, with sound to match. The line-stage was ultrasilent, and, with its simple, elegant circuitry, close to neutral when referenced to the EAD straight out. But for the slightest compression on dynamic peaks, a mild sensation of tube "glow" and a bit of added liquidity, the Jadis was neutral. What it added was more than pleasant, and didn't mask vital musical information. The all-tube phono stage was another story: while it sounded detailed and sweet and could handle very-low-output moving-coil cartridges, it was noisy with the Clavis, the Dynavector XX-1L, and other low outputters. When the music wasn't loud, the tube rush was, despite the importer's insistence that the unit was sufficiently quiet. When I left TAS, the Jadis left my house, review unwritten. But I was impressed.
But not good enough for my needs in 1995. What to do? I borrowed a friends Audio Research SP-11 Mk2 for a spell, but finally I decided what I needed to do was buy an Audible Illusions Modulus 3. Seeing as how I'd recommended it without reservation in TAS based upon hearing it in other people's systems, and given its very reasonable price (then about $2000 with moving-coil, phono board), it made sense. I give you a short history because this is my first electronics review in Stereophile, and I hope the added perspective will lend more gravity to what you're about to read.
As my friend Tony Chiarella pointed out in his Modulus 3 review in TAS a few years ago, Art Ferris, the man behind Audible Illusions, began his audio life as a dealer in precious antiquities: vintage McIntosh and Marantz gear that he exported to Japan in great quantities. So blame him if you can’t find or afford the stuff. When the supply began to dry up in the early '80s, Ferris, trained as a graphic designer, began marketing Audible Illusions' original Modulus preamplifier overseas, hoping to whet the Asian market’s appetite for American tube gear. Eventually Ferris took control of the company in an effort to improve production, quality control, and the budget-priced product itself, which had already garnered a series of favorable reviews worldwide (including JGH's footnote comment in Stereophile in October 1984, Vol.7 No.6, p.51, that "the Modulus is a steal at its modest price") and a loyal following in the then "audio underground." Ferris's electronic tinkering gave way to serious design chops, cheered on by the likes of Saul Marantz, the mysterious John Iverson, John Curl, and others. Over the last decade, the Modulus evolved into the Modulus 2, which underwent biannual revisions until 1992. Then it was replaced by the Modulus 3, which sold for $1495 complete with an all-tubed MM/high-output-MC phono stage. Add $500 for the optional John Curl-designed solid-state low-output MC Gold Phono Board.
The faceplate is a substantial, 1/4" thick, finely-finished metal stab; the four meaty control knobs are beautifully machined from aluminum. The top cover is secured with nicely-finished hex-headed screws. Connector layout on the back is spacious; it's easy to access the first-rate Teflon-dielectric, machined RCA jacks that are bolted to the chassis and hard-wired to one of three circuit boards inside. The rear complement includes two sets of main outputs for easy bi-amping. Front-panel layout is simple, too: source selector (a generous six inputs), tape monitor, and dual volume controls. Two pushbutton switches flank the knobs: low-frequency filter and Stereo/Mono switch on one side, Mute and On/Off on the other. A non-detachable umbilical cord connects the main chassis to the hefty power supply, which is housed in a 5" W by 3½" H by 10" D chassis. While the unit is simple, there's nothing "budget" about the Mod 3 outside or inside, where you'll find an extremely high-quality, oxygen-free copper, double-sided, "star-grounded" main board loaded with high-quality mil-spec parts including high-grade 1% resistors and custom-designed polystyrene and polypropylene capacitors (more small sausages) in the signal path. Of course, the only Mod 3 inside you'll see from now on will be that of a used Mod 3, since it has now been superseded by the 3A. Construction quality, especially the soldering, is superb. Each solder joint is a virtually perfect, round little mirror. Vertically mounted boards, front and rear, connect inputs, outputs, and controls to the main circuit card, which also holds the four 6DJ8/6922 tubes— two for the phono section, two for the line stage. My original Mod 3 came equipped with the Curl-designed gold phono board. More about the circuit design and sundry adjustments later— when we get to the new 3A. Since there's a new model, why am I obsessing on the old one? Read on!
The Modulus 3 sounded neither "tubey" nor solid-state "zingy." No matter what I pushed it with, I never detected strain, congestion, or compression. The 3's ability to portray wide dynamic swings and the smaller ones that make music sound real was absolutely superb, as good as anything I've heard— and even at the lowest levels of music-making, the background was as velvety quiet as that of the best solid-state preamps. Except for the deepest bass control, a bit of bass dynamic compression, and a lack of sparkle and resolution at the very top, the 3 beat the SP-11 by a considerable margin —especially in terms of transparency— and despite the few areas where it fell short, I'd pick the Modulus 3 over the older (and much more expensive) Audio Research unit in a New Jersey minute. Images were sharply drawn and focused yet totally free of artificial edge; and separation, soundstage width, depth, and height were limited only by the recording. You’re waiting for the other shoe to drop?
Good as what was there was, what was missing left me an unhappy camper. I worried that the combination of the 15' cable run from preamplifier to arnplifier and the lack of an output buffer (no cathode follower, more on that later) was rolling-off the high frequencies. I pulled the unit and set it up a foot from the amps. No change, so it wasn't that. Look, the original 3 was and is a terrific product, clearly one of the best preamplifiers on the market irrespective of price. But I was using it with very revealing and very expensive associated gear, and my very high expectations weren’t being met at the extreme top and bottom, where, despite outstanding extension, there was a lack of ultimate authority and timbral and textural nuance. Since I knew the rest of my system could deliver the goods, the 3 was the weak link in the chain.
So I did. I ordered a pile of dots from Marigo Audio Labs in Skokie, Illinois, and placed them as instructed on top of electrolytic caps, transistors, and IC’s (power-supply regulation), on the power transformer, on the chassis, on circuit boards at strategic locations, and on my forehead before listening to Ravi Shankar. And based on conversations with a number of Mod 3 aficionados, I substituted a Marigo power cord for the factory job. I placed the 3 on a Bright Star Big Rock 3, mass-loaded with a Bright Star Little Rock, which sat on three inverted cones to allow adequate chassis ventilation. Obviously I chose that option over leaving the top cover off. The results of my tweaks? Significant improvement in bass focus and transient snap, but still not enough to satisfy. I'm not an easy customer.
When Audible Illusions offered to gut my unit and turn it into a 3A, I was more than happy to oblige— after removing all those Marigo dots and saving them on a sheet of waxed paper. What I got back a few weeks later looked the same on the outside, but not on the inside, where the new main board is densely packed with even more high-quality parts than the old one. While the basic circuit design remains unchanged —in tube amplifier design, Art Ferris claims, there's really nothing new except for better parts and power supply designs— there are major differences between the 3 and 3A, not the least of which is the price: the 3A without the M3 Gold MC board now costs $1895! This is still a bargain for what you get physically and sonically. There are now seven separate regulated power supplies— each section of the preamplifier now has its own dedicated supply. Relay switching is now used to cut down signal-path length and to provide true monophonic blend when the Stereo/Mono switch is utilized. The 3's Stereo/Mono switch narrowed separation but didn’t fold down completely— an important feature when you play mono recordings. The 3A features a much larger main power supply, the transformer of which is now manufactured by Audible Illusions instead of being sourced from the outside. There are other differences between the 3 and 3A, but more significantly, there are bigger differences between either Audible Illusions preamplifier and most others. Take the one-tube/channel line-stage: each 6DJ8 is a dual triode, which in the 3A is operated with the two halves paralleled in high-current class-A mode with no feedback— "balls to the wall," as Ferris likes to call it. Another commonly used tube circuit, the "cathode follower" that serves as an impedance transformer and output buffer, is absent in Modulus preamps. Followers do lower impedance and allow a preamplifier to drive long lengths of interconnect, but according to Ferris again, the extra circuitry adds noise, veils the signal, and can cause phase shift. Without an output cathode-follower circuit, a preamp can suffer from high-frequency rolloff with long or high-capacitance interconnects. To minimize the possibility of this happening, the Modulus uses a combination of unique circuit techniques and special parts to up the current drive and lower impedance. Because the tube is run in parallel, in the 6DJ8's normal 3.2k impedance is cut in half to 1600 ohms— which, though closer to ideal (most tube preamplifiers have about a 600 ohm output impedance), is still high in absolute terms. Other circuit innovations enhance the preamp's drive capabilities. Specially designed conductive-plastic potentiometers minimize the capacitive loading effects of conventional pots. The result is a low enough source impedance (1.2k ohms) and high enough current capability for the Modulus 3A to drive long lengths of cable into even low-impedance (10k ohms) amplifier inputs without instability or high frequency rolloff. Because the line-stage flips phase, the main output of the Modulus 3 and 3A is absolute-phase-inverted. To restore correct polarity, you simply reverse your speaker cables: hot to ground and ground to hot on both channels. The Curl-designed solid-state tape-output buffer circuit doesn't invert phase. The Modulus's one-tube/channel phono stage obviously doesn’t use the commonly implemented "cascode section" for voltage gain (two tubes run in series) because again Ferris feels this method induces an unacceptable amount of phase shift. Yet the Modulus offers almost 60dB of overall gain (28dB phono at 1kHz/30dB line), low distortion, and outstanding S/N ratio using active RIAA equalization in combination with very low overall negative feedback. For low-output coil cartridge fanciers, the John Curl-designed M3 solid-state gold board (circuit traces and ground plane etched in gold) adds $500 to the 3A, bringing the total cost to $2395. The gold board, with factory-adjustable gain between 22 and 30dB, is essentially a somewhat simplified version of Curl’s fabled Vendetta Research phono section (single FET vs the Vendetta's dual FETs, which results in somewhat higher noise, though noise, even with the lowest-output coil cartridges, is not a problem with the 3A). More than simply a head amplifier placed in front of the phono section, the gold board is integrated into the RIAA section of the tubed phono stage, which then has to be custom-trimmed to meet RIAA specs. All of this circuitry is driven by a sophisticated low-impedance power supply capable of wide voltage swings: the 3A is said to reproduce a perfect 10kHz squarewave, and is almost perfect at 20kHz.
Using a series of very demanding orchestral CDs —including a number of Shawn Murphy-engineered sound-tracks, all of which are recorded using a Kenneth Wilkinson-style "Decca tree" mike setup— I compared them to the EAD direct out and through the Mod 3A. The Murphy recordings, including Dances With Wolves (Epic ZK 66817 gold CD), Casper (MCA MCAD-11240), Moviola (Epic EK 52985), and Batman Returns (Warner Bros. 26972-2), feature stupendous bass, gigantic soundstaging width and depth, rich string tone, outstanding portrayal of inner detail, and thunderous dynamic range— none of which will come as any surprise to "Wilkie" aficionados. Any of these, and virtually all Shawn Murphy soundtrack recordings, are audiophile-quality demo discs. Bottom line is, I was hard pressed to hear any significant differences between the EAD direct out and through the Modulus 3A. I concentrated on bass-drum impact and focus, string tone and texture, ambience, soundstaging— you name it. If I noted any consistent difference, it would be an ever-so-slight overall darkening of sound. But so slight that I noted bigger differences when changing the interconnects between the EAD's analog outs and the Mod 3A’s inputs, so we're talking very minor. The one-tube/channel line-stage of the Mod 3A is virtually transparent and ultraquiet. As for the phono input, where there can be no "direct reference," with the low-output Clavis D.C. or the new AudioQuest 7000 Fe5, I can tell you, there's more than enough gain for them to perform on a bed of utter silence. What’s more, whatever bass sluggishness I'd noted with the 3 was gone. The midrange was as glorious as before, and the top was extended and detailed without etchiness or glare. Large-scale dynamics were explosive top to bottom, and well-controlled, as were the small dynamic gestures that create inner detail and a sense of living, breathing music. Everything was right with the 3A referenced to my experience listening to live music— not that my stereo sounds like live music; no one's does. For those into playing with impedance loading, the gold phono board is factory preset at 47k ohms, but that can easily be changed by inserting the desired-value resistor into gold-plated pins on each board.
The Sonic SFL-2 offers features the Modulus doesn’t —balanced inputs and outputs, for example— and its performance and construction are clearly Class A, certainly in the same league as the Modulus, though I think the Modulus is even more transparent and liquid-sounding. In my opinion, though, the SFP-1 phono stage doesn't perform well with low-output coil cartridges: its relatively high noise floor and only moderate gain cast a grayish veil over the soundstage and impart a sluggish rhythmic quality to music. I can't square what I hear with the comments in Stereophile's "Recommended Components" listing for the SFP-1. If it is "marginal Class A," then the Modulus’s phono performance is Class A+. And the SFP-1's lack of a mono switch is a serious shortcoming for those of us who want to listen to the many outstanding monophonic records available, without putting up with superfluous vertical-groove modulation.
If you want to be able to listen to one source while recording another, you won't find that option on the Modulus 3A. In addition, because the 3A’s design values "hot-rodded" simplicity over convenience, if you opt for the gold board, you're warned that "Tube preamplifiers; have high DC voltage surges. Although the Modulus was carefully designed to incorporate a safety relay circuit that protects your system, internal circuitry could conceivably be damaged due to DC voltages being amplified by the additional 30dB of gain from the Gold Phono Board during turn-on cycle. Though safety diodes are built in to shunt these voltages to ground, we strongly recommend that you develop the habit of turning the selector switch to one of the line inputs, (ie CD), prior to turning the unit on rather than leaving the selector on 'Phono'." You' re warned elsewhere that if you accidentally transpose your "tape in" with your "tape out" you can seriously damage the tape buffer. I mention these caveats because high performance is only one piece of the product pie. The above is certainly a consideration when choosing a product. On the other hand, a high-performance automobile is more likely to spin out of control than a family sedan. It all depends on what you want and what you need. Keep in mind that tile Modulus's reliability in the field is extremely high, so don't let those warnings scare you away. You just need to exercise some common sense. Another caveat: Despite selling over 15,000 Modulus Preamps, Audible Illusions is still a small, somewhat quirky company. I've heard complaints about availability of product, and about long downtime when repairs are needed. Make sure you buy from an established dealer; don't pay in advance for a unit to be shipped; and work out your own terms if your unit does need repair. I raised some of these issues with the company, and was told new procedures and manufacturing improvements should make these problems a thing of the past. — Michael Fremer
MF’S SYSTEM Cables: XLO Signature 3.1 phono cable (JS is right on the money describing this); otherwise A.R.T. and Yamamura Systems Millennium 5000 interconnect and speaker cable throughout (MF is right on the money describing this!). A.R.T., Transparent Audio, and Marigo Labs AC cables. Accessories: Bright
Star Audio Big Rock, Little Rock TNT base. Townshend Audio Seismic Sink (under Bright Star
TNT base and T-7000 transport). Harmonic tuning feet under Modulus 3A, A.R.T. TR-30
contact cleaner, Audio Industries Power Wedge (front end), Harmonix room tuning discs, and
ASC Tube Traps.
MEASUREMENTS FROM TJN The DC offset at the Modulus 3A’s outputs measured a maximum of 29mV in the left channel and 37.6mV in the right, though the values fluctuated considerably. The preamp is inverting from line input to output but its phono stage (phono in to tape out) is non-inverting, the polarity of all inputs will therefore be inverted at the main output. Maximum line-stage gain measured 28.4dB, phono gain 53.9dB. The line-stage S/N ratio (ref. 1V, unweighted) measured 83.3dB from 22Hz-22kHz, 71dB from 10kHz- 500kHz, and 87dB, A-weighted. Phono-stage S/N measured 81dB, 72dB, and 87.6dB, under the same conditions, respectively. The latter are very good figures for a moving-coil phono stage. The Modulus 3A’s line- and phono-stage frequency responses into a 100k load measurements were taken with the volume controls physically matched. Despite MF's experience, I found tracking to be up to 0.5dB off under those conditions. [While the RIAA error meets AI’s specifications, I would expect the response rise in the bass to be audible as a slight warming of the sound. The rise above 10kHz might also be just audible and is due to the RIAA topology used, where the phono-stage gain doesn't continue to drop with increasing frequency but levels out at unity gain. —Ed.] The 3A’s crosstalk/separation is not as good as the best we've measured for line-stages, nevertheless these are audibly inconsequential amounts of crosstalk. The high-frequency increases are typically the result of capacative coupling between channels. The manner in which THD+noise varies with frequency for the Modulus 3A measure good results. The spikes visible in the phono result are intermittent artifacts apparently due to fluctuating noise levels; they appeared at different points when the measurements were redone several times. The change in THD+noise with output level was measured using a 1kHz signal. Both the phono and line- stage distortion and crosstalk measurements were taken at an input of 100mV, which results in a distortion just slightly above minimum. The same measurements for the phono stage were taken at an input of 4mV, which resulted in an output very close to the minimum and minimized the effects of noise on the measurements. The Audible Illusions phono stage would accept an (unequalized) input of 13.4mV at 1kHz, 141mV at 20kHz, and 0.48mV at 20Hz at a THD+noise level of 1%— very respectable figures for a moving-coil stage. The variations with frequency are simply the result of the phono equalization characteristics (RIAA); there's considerably less bass energy engraved in the grooves than high-frequency energy. Finally, the 3A's output spectrum reproducing a line-level 50Hz input at a high output of 5V into 100k ohms. shows the largest artifact is the second harmonic, at -51.7dB or about 0.25%. At a more typical output of 1.5V, the second harmonic decreases to -62.2dB (about 0.08%) and the remaining artifacts drop below -90dB (0.003%). Our measurements of the Modulus 3A don’t agree down the line with the measurements AI included with our sample (for logistical reasons, this was not the same sample auditioned by MF). Nevertheless, the only notable discrepancy involves the line-level frequency response, which we measured as rolling off above 10kHz but which Audible Illusions shows as only 0.7dB down at 100kHz. In my experience, the latter would be excellent performance for any preamp, and very unusual for a tube design. Our results aren’t at all unusual for a well-designed tube preamp— which is exactly what the Modulus 3A appears to be. Only the slightly high output impedance suggests that some care should be taken in matching it with a power amplifier, for which I would recommend a minimum of 20k ohms input impedance. — Thomas J. Norton
Because of the circuit’s simplicity, tube quality has a greater-than-usual effect on the sound. I've been told by Modulus aficionados that certain brands of NOS (new old stock) tubes improve the sonic performance. Perhaps I'll have a chance to experiment later, but for now I'll stick with supplied tubes, which should last for many years and are inexpensive to replace (about $60 to retube the entire preamp). The Modulus 3A offers the highest level of performance at a bargain price. It even allows you to switch out the line section's bypass caps for even purer sound (that’s how my unit was run for this review), and there's a carefully implemented 7dB line-section gain-limiting switch if your digital source has very high output, thus allowing a wider range of volume-pot control. if you don't need a phono section (poor you), Audible Illusions' Ll line-stage offers the same performance, plus a neat headphone amplifier, for $1495. All of this adds up to what is clearly one of the finest-sounding, best-built full-function preamplifiers in the world— and reviews from around the world reflect that. The best? With Audio Research's PH-3 phono section waiting in the wings, I'm hesitant to say, but looking at the cost of the associated equipment used in this evaluation, when I tell you that the Modulus 3A is in the same league and costs just $2395, you ought to listen. — Michael Fremer cStereophile-Vol.19 No-2
MANUFACTURERS COMMENTS AUDIBLE ILLUSIONS Editor: On behalf of the many Modulus owners and our dealers who have faithfully supported our preamplifiers over the years, your comprehensive product review of our Modulus 3A is most welcome. Mr. Fremer’s "passion" regarding his knowledge of music and high-end audio is most obvious. We are honored that he has become a Modulus owner and has devoted such effort to writing his report. Over the years much has been written about the good sound of our products, and I seldom comment on subjective reviews. What most pleases me about this review is MF's recognition of our construction quality and reliability. Our company has long suffered the learning process to successfully manufacture a cost-effective high-end tube preamp. Believe me when I say there are people in our factory who, with respect for perfection, easily match Mr. Fremer’s passion. These are American workers at their finest. They love the preamp, and their craftsmanship shows! Our company also welcomes the opportunity to respond to MF's caveat concerning product repair downtime. I assume he refers to our amplifier, as statistics for our Modulus preamps show only a 0.04% problem rate for the Me C-D series and approximately 2-3% for the M3 series. We seldom see a Modulus in for repair, and typical in-house warranty repair rarely exceeds one week. Any Audible Illusions dealer will confirm that the Modulus is the most trouble-free tube product they sell. The few S120 amplifiers we made were reliable, but some suffered from customer misuse. The difficulty we've experienced is that several S120 parts were single-sourced and are no longer made. Subsequently, we've had to discontinue S120 production until our redesign has been proven. Product availability is also a serious concern to us. We feel our customers are entitled to visit their dealer, pay for a preamp, and receive it within a reasonable time. We've now decided that some of our dealers who do not carry adequate back-up stock must be replaced. We also have installed a hotline to handle customer questions: (925) 463-2381. Your technical measurements differ somewhat from ours, but that can be expected as test equipment and methods differ. One notable exception we have is your method of measuring line-stage frequency response. We prefer to measure this stage tape-in through main output as this is a more straightforward path. Retesting, using your 100k load, we measure -0.25dB at 50kHz, volume controls set at 9:00 and at open. Through the CD input we measured -0.75dB at 50kHz, volume controls at 9:00 and -1.5dB, volume controls at 12:00. Please note both digital inputs of the M3A have resistor dividing networks to cut the input gain of many hot-output CD and DAT players. We feel it's also beneficial that these resistors do in fact impart a very slight high-frequency rolloff which tends to attenuate much non-musical digital "garbage" above 20kHz and does improve the sound of the cheaper CD players. For better-quality players the option always remains to use the auxiliary input with no rolloff or to modify these resistors. Other features incorporated into the M3A design allow the preamp to be voiced/adjusted to a particular system or listeners tastes. These features are discussed in the owner’s manual. Incidentally, the intermittent noise spikes noted in your THD phono measurements are the result of circuit components not completely broken-in, particularly our large film and foil polypropylene caps. Please note, in order to meet Stereophile's deadline, we rushed to take a unit off the line and FedEx it to Santa Fe. The preamp only had minimum bum-in time. For proper break-in we recommend a minimum of one month’s continuous use before the unit completely settles in and the sound opens up to reveal the M3A’s outstanding imaging qualities. It has always been our goal for Modulus preamplifiers to be of the highest quality, user-friendly, and to bring much musical happiness. We're most proud of the fact that 80% of the Modulus preamps sold are still in use by their original owners, whose calls and letters of support have sustained our spirits through many dark hours. Truly, this preamp is a labor of love; it's nice to be appreciated. Thank you, Stereophile. Art Ferris |
