Herron Audio: Prima; Vinyl Exchange review

From PRIMYL VINYL EXCHANGEVolume 2 Number 6
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The Herron VTPH-1 Phono Stage

First things first, again. The Herron VTPH-l is, overall and by a good margin, the best phono stage I've heard. At $2750 MSRP for MM, and $3250 for low output MC, it also happens to be the most expensive piece of gear I've allowed in my system, but it is hardly the most expensive phono stage on today's audiophile market. A quick glance through the '97 Audio equipment directory turned up a couple dozen more expensive units, as well as a host of full-function preamps with internal phono stages well above the price. Most of which I have not heard, of course, but it does seem a telling commentary that so many manufacturers view LP reproduction as such a priority in high end design. In Keith Herron we have a previously unheralded designer with the audacity to introduce an upmarket, tube based phono stage as his first product (a tube linestage is in the offing). The buzz on the unit has been very good, and my brief (and unofficial) audition at Hi-Fi 97 further whetted my appetite. I requested the MM version for review, and later got to hear the MC version, courtesy of Roger Gordon of Positive Feedback magazine.

The two units are outwardly identical, full-width black boxes of conventional but quality construction. The back panel has the RCA in/out connectors (no balanced options) and ground (all high quality Tiff's-even the ground), a removable IEC AC cord socket, and two rocker switches-the usual on/off, and a second marked AC Polarity (not so conventional). The front panel has three LEDs which light up sequentially at turn-on, allowing the filament voltage to ramp up smoothly, and muting the circuit until ready. In practice, Herron recommends simply leaving the unit on. There are no front panel controls.

Whatever it's mild-mannered exterior, the VTPH-1 is impressive on the inside. On the right is the substantial power supply section, with the shielded toroidal transformer and a phalanx of capacitors - 78,000 µF, more than a lot of amplifiers. To the left is the main (44dB) gain and RIAA circuitry, utilizing 4 hand selected Sovtek 12AX7WB dual triodes and a single Philips 12AT7WC. RIAA EQ is passive, and extended from 1 Hz to over 100kHz, and within +/-.1 dB between the normal 20Hz to 20Hz limits. Unusually for a phono stage, there is no 20Hz subsonic or "rumble" filter-most modern turntables are extremely quiet, and thus there is no need to compromise the superb low frequency performance. No feedback is used in the audio circuitry, and star grounding is employed throughout.

The MC version differs from the MM essentially through the addition of a small (2"x3") circuit board with a precision FET headamp (22dB gain). To keep the signal path as short as possible, the FET board is vertical, and mounted directly to the input RCA jacks, with provision for soldering additional loading resistors (47k ohms is standard). Herron is thoroughly disinclined to put switches in the signal path, even if it means an occasional inconvenience. If you run several different cartridges (a MC for stereo, a MM for mono or 78s perhaps) there's no way of defeating the extra gain. Well, you "can" run a 5 mV MM through the MC version-there's plenty of head room-but only if the preamp's input impedance is 50k ohms or higher-and the preamp's volume pot will barely be cracked open. However, the 44 dB gain of the MM version is only 10-12 dB less than some "MC" stages provide, so in many systems even cartridges in the .5-.6mV output range will keep the noise floor below audibility (S/N ratio is 80 dB, A weighted). Herron suggests 1.0mV output as the decision point, thus making the many owners of Benz Gliders writhe in unnecessary agony. Relax, guys - the MM is fine at .1 mV, and can be upgraded to MC for about the original price differential if ever necessary.

If you're getting the drift that this is a true purist's idea of a phono stage, it will make sense that Herron hand matches the capacitors in the RIAA EQ circuit to within .1% of spec, and that the tubes are burned in, tested, and hand matched-and that the finished units get a 48hr burn-in before final bench and listening tests. This is not an approach which lends itself to the economies of mass production; I does set a quality standard which is reassuring in a product from a new, small firm. As it happened, one of the Sovtek tubes developed a noise problem, requiring a call to St. Louis. Keith Herron calmly talked me through the fix (a simple tube swap), explaining the circuit intricacies as we progressed. Think Gary Cooper as air traffic controller, not Microsoft Technical Support, here.

You noticed I left my comments on the sound for last? Well, I started with the MM version, fed by the Grado Reference Platinum in the Well-Tempered. As good as the VTPH-1 sounded in my system, it had seemed even better in San Francisco. Coincidentally, I had come back from SF with a sample of the JPS Labs Superconductor interconnect. Remembering Herron had suggested low capacitance cables, I substituted it for one of my pricey silver ones. The sound opened up so significantly that I ordered another set for the pre-to-amp run. The bass and sense of three dimensionality improved dramatically with the JPS cabling. Sensing a synergistic combination, I brought them around together to friends and dealers. Superb presentation on an Michell/Air-Tight/Gallo Nuclei system at Sound Images and Clark Johnsen's gigantic VMPS rig. But curiously, nothing special in a friend's aging Vandersteen 2 setup. At home, I added the JPS speaker cable and AC power cord, yielding further improvements. Prospective purchasers should definitely anticipate cable and AC cord contests and upgrades. (The AC polarity switch on the Herron, by the way, is just that. Audiophiles often use 3/2 prong "cheater" adapters to reverse AC line polarity, but this usually also lifts the ground connection. The Herron approach maintains the connection to ground while minimizing line-to-chassis reactive currents and noise pickup. The switch does not invert signal polarity.)

One can also certainly substitute other brands of tubes, but all bets are off on the +/- .1 dB RIAA accuracy and 80 dB S/N specs, of course. I tried swapping the NOS Telefunken tubes for the stock Sovteks. The VTPH-1 did absolutely nothing to dampen my affection for NOS Telefunkens, sounding remark ably luscious with the antique glass. However, it is voiced with the Sovteks, so I left them in for all comparisons.

When the MC version arrived, I switched to the van den Hul MC 10 in the Logic DM101/PT-8. Familiar records sounded a bit muffled-until I remembered the MC version inverts absolute phase. Switching the speaker leads brought back the magic, and thus confirmed that the extended RIAA curve maintained accurate phase response: system polarity is unambiguous. Time to take on some big guns, I figured. In a Basis/Spectral/Avalon Radian HC suite at Goodwin's High End I was treated to an enormous, walk-through 3-D soundstage and splendiferous bass. Same results with a friend's Basis/VTL/ Infinity IRS mega-system. He runs a Vendetta phono stage into an Audible Illusions preamp, a combination so bright he had half-covered the tweeters with masking tape. The Herron had superior timbre and soundstaging, the Vendetta more detail and attack. However, The VTPH-1 also aggravated an existing hum problem in that system, apparently a combination of tonearm grounding and cartridge loading. (There were no hum problems in the other systems I tried). More recently, Clark Johnsen invited me (and the VTPH-1) to a face-off with the excellent $6000 TA-3000 phono stage from Thor Audio. Here, the results were somewhat equivocal, comparisons complicated by absolute polarity issues-the Thor being non-inverting. Our host deftly switched the cartridge clips between playbacks, an effective alternative to speaker-lead swapping, but not for the faint of heart. The Herron was judged to have better bass definition and extension, and was quieter (even excluding a hum problem afflicting the Thor). Some of the listening group preferred the Thor's HF presentation, hearing clarity where I heard forwardness, but these were not major differences. I'd call it a draw, and cigars all around. The Herron Phono Stage - either version, in my opinion - belongs in that select group of extraordinary products which can raise the bar in the analog Olympics yet another notch (or six). Partnered with some of the best cartridges, arms, turntables, electronics and speakers I could muster, it never seemed the weakest link in the chain.

Conclusions? Life is full of tough choices, ain't it? Other phono stages - solid state designs as well as tube products - will offer alternative versions of what actually lies in that mysterious groove. Anyone considering a purchase at this level should certainly make their own comparisons, in the context of their own system. End requisite reviewer's disclaimer. Personally, I preferred the Herron to everything I compared it to - and by a considerable margin, although the lack of MM/MC switching is frustrating, and the price will be a factor for many audiophile/collectors. Still, sometimes you get what you pay for - in this case, a remarkably musical restoration of the recorded event. If you haven't heard LPs played through a top-flight modern tube phono stage (and associated gear), arrange an audition of one of these babies ASAP!