No preamplifier, no cry
Short a preamplifier, I drove the VTL 300s with the EAD straight out for CDs while for analog I resurrected a Dynaco PAS-2 I'd picked up at a garage sale for $5 (along with a Stereo 70 fitted with Amperex "Bugle Boy" EL34s and a mint Scott 350 stereo tuner thrown in). All four gold-pinned Telefunken 12AX7s in the Dyna passed Tube Testing 101, and the unit wasn't spitting any DC nasties, so I cautiously inserted it into the system, replacing the Clavis with a $125 Grado Signature Jr. cartridge (nice!). Hello vinyl, bye-bye neutrality. But for five bucks, what the…
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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 (some the size of 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 Of course, the only Mod 3 inside you'll see from now on will be that of a used Mod 3, since it has now been superseded by the 3A.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…
So I did. I ordered a pile of dots from Marigo Audio Labs in Skokie, IL, and placed them as instructed on top of electrolytic caps, transistors, and ICs (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…
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 $…
Frontiers
Is the Modulus 3A the finest preamplifier in the world? I don't know. I can say this: when I raved about what I was hearing to Stereophile headquarters in Santa Fe, I was drop-shipped a Class A recommended preamplifier for comparison: the Sonic Frontiers SFL-2 line-stage and SFP-1 Signature phono-stage which are also based on 6DJ8 tube technology. Total cost: close to $5000.
Is the Modulus 3A the finest preamplifier in the world? I don't know. I can say this: when I raved about what I was hearing to Stereophile headquarters in Santa Fe, I was drop-shipped a Class A recommended preamplifier for comparison: the Sonic Frontiers SFL-2 line-stage and SFP-1 Signature phono-stage which are also based on 6DJ8 tube technology. Total cost: close to $5000.
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,…
Sidebar 1: Specifications
Description: Phono section gain: 28dB at 1kHz (MM), 27dB (MC). Line section gain: 30dB. Output impedance: 1.2k ohms (main), 150 ohms (tape). Input impedance: 47k ohms. Frequency response: 2Hz-100kHz within 1dB, measured with a 1:1 probe/100k ohm load. Phono section RIAA error: 20Hz-20kHz ±0.25dB. Distortion: 0.02% (MC phono section); ±0.015% at 20kHz (MM phono section); ±0.15% at 1.5V RMS out, 20Hz-20kHz into 50k ohms, ±0.12% at 500mV RMS out, 20Hz-20kHz, into IHF load (high-level section). S/N ratio: 74dB ref. 5mV wideband input (MM phono section); 85dB ref. 1.…
Sidebar 2: MF's System
Analog: VPI TNT Mk.3 turntable; Graham 1.5t arm or Rockport Capella linear-tracking air-bearing arm; Clavis D.C. or AudioQuest Fe5 cartridges.
Digital: EAD T-7000 transport, EAD DSP9000 Mk.3 digital processor; Audio Alchemy DTI•Pro 32 digital interface.
Amplifiers: Cary Audio 805 single-ended triode or OCM 500 solid-state.
Loudspeakers: Audio Physic Virgo or ProAc Response 2.5.
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…
Sidebar 3: Measurements
Line-level measurements of the Audible Illusions were taken from the CD inputs to the main outputs; the phono measurements were taken at the tape outputs.
The Modulus 3's output impedance at its line output measured 1775 ohms (L) and 1802 ohms (R) with the level controls at maximum; lower settings of the main level control changed this measurement by only a few ohms. The input impedance at the CD input was just over 48k ohms and wasn't significantly affected by the main level control's setting. The output impedance at the tape output was 248 ohms…
The change in THD+noise with output level using a 1kHz signal is shown in fig.4. Both the phono (top) and line-stage (bottom) performances are shown. The distortion and crosstalk measurements of figs.2 and 3 for the line-stage were taken at an input of 100mV, which results in a distortion just slightly above the minimum shown in this figure. The same measurements for the phono stage were taken at an input of 4mV, which resulted in an output very close to the minimum on the phono stage curve in fig.4 and minimized the effects of noise on the measurements.
Fig.4 Audible Illusions…
Sidebar 4: Follow-Up from Stereophile September 1996, Vol.19 No.9
MF compares the Audio Research PH3 and Audible Illusions Modulus 3A
When you audition a component for the first time, usually what you hear are the gross differences between it and your reference. You may hear new things in favorite recordings, but such changes are meaningless. It's like cranking up the treble, hearing previously buried information, and calling it an improvement. Over time, however, I was able to develop a predictable "difference profile" between the two phono sections, which I would apply to…