American Hybrid Technology phono preamplifier Page 2
In comparing the AHT's sound to my reference CAT Signature, both wired up system-wide with XLO Signature (which I consider far and away the best sounding of all the cables I tried), I'd say that the CAT delivered a more dynamic (micro and macro), rounded, full, harmonically rich, tube-like, and neutral sound. The CAT was less dry, with a noticeably deeper and wider soundstage, and clearly more palpable and ambient than the AHT.
The long and short of it was that the CAT was more involving. But for the AHT phono stage to come along and so capably play in the same Field of Dreams as the big boys is a remarkable achievement. I never felt I was being shortchanged by the AHT, never caught myself harboring a desire to switch back to the CAT during listening sessions. Ask me while it's playing if I love the AHT phono stage, I'd say yes. Switch the CAT back in and ask which I prefer, I'll tell you the CAT.
Tube fanatics might find Nirvana with the layering, neutrality, and stunning energy of the CAT, or the smooth, silky musical presentation allied with vibrant dynamics of the Jadis JP 80 MC. However, solid-state fanciers will find a lot to love in the AHT Phono Stage, especially at $2500.
Tweaks & cables
Once adjusted for loading and output, the diminutive, all-IC Phono Stage can be left to sit like a brick, or adjusted by the tweakish among us ad infinitum. I used the heavy Forsell weight on top of the AHT to weigh down a Shun Mook Mpingo disc (the Shun Mook Record Weight having taken up duties on the Forsell), and supported the resultant odd-looking contraption on four small Combak Counter Feet placed in turn upon an Arcici Isolation Platform. The power supply was supported on three Marigo Labs footers or Arcici Super Spikes for a clearly discernible improvement. A scattering of Original Cable Jackets also lowered residual system noise and further opened up the unit. A dealer I know who handles the AHT also places an Mpingo Disc atop his unit, then covers that with a smallish Davidoff cigar box filled with #9 lead shot and puts the whole construct up on Goldmund cones. I know of yet another devoted audiophile who let Fanny solder the wires from his Forsell directly into the AHT's phono-stage inputs. Some of us are committed. Some of us oughta be committed. This direct-connect soldering is a good idea, of course. The powers of KISS (Keep It Simple, Stupid) and short signal paths still apply.
The biggest improvement in the Tweaks 'R Us Department came from adding five Combak Tuning Belts to the circuit board (four at the corners, one in the middle). Two Belts were also added to the outer case between the input and output jacks for both left and right channels. The addition of the belts narrowed the apparent differences between the AHT and my admittedly heavily tweaked CAT (footnote 3). The bass became tighter and deeper, kicking out more impact and slam. Dynamic contrasts were markedly improved, which may account for the increased inner detailing I heard right away. Art Farmer's fluegelhorn could more plainly be heard to swing about during the recording of his Perception album (Argo LP-738), the instruments moving more forward out of the ambient mix, the recording venue more easily determined. Listening to Ella Fitzgerald's Fine and Mellow (Pablo 2310 829), Ella's remarkable voice sounded that much more human, seeming to occupy "real" space in a more realistic and relaxed manner.
To further "refine" the tweaks, add Combak/Harmonix Refine RF-414 Tuning Rings to the phono links on both sides of the AHT unit and you'll find that the highs open up and imaging improves; the Rings seem to attenuate RF at the RCA jack (the RF-414's inside ring is fabricated of Mumetal). An RF-414 ring at the electrical input to the phono stage further "refined" its presentation.
That's all the good news, tweakwise. The bad news is the price one has to pay for these exotic but remarkably effective appurtenances which elevate the AHT's prowess along with its bottom line. But tweak we must...
For the ultimate tweak, the AHT has sufficient gain that it can be run direct into your amp(s), bypassing the preamp completely. You might be tempted, as I was, to try this and use resistors alone to change the volume. Can you say, "Transparent"? But real-world, you have to be able to control the volume; many will chose to line-stage the device. I suspect it might sound killer in a system optimized around a passive unit, or one with minimalist gain controls. I did try it with the beautifully built Reference Line Preeminence passive preamp, but the 5.5m wire run to my amps proved too long to sustain the dynamics.
Being an old XLO hound, I wired up the Avalons with the new, fabulous, and immediate-sounding Signature Type 5.1 speaker cable, which proved to be my favorite. I also auditioned Purist Colossus speaker cable, which delivered its usual musical, mid-hall, non-etched but very "real"-sounding, concert-halllike presentation. Later on I tried the new and intriguing Mapleshade Omega Mikro-Planar speaker cable. These good-sounding, harmonically rich, but slightly diffuse (in comparison to XLO), lightly sheathed, featherweight, flat copper cables surely get the reward for bizarre cable of the month. Say, Happy Audio Homemakers, stay away from them with the vacuum cleaner!
Taking the absolute hell that is audio reviewing to heart, I experimented with the following interconnects: XLO Signature (once again my preferred connection), Purist Audio Colossus, Pure Logic's Raj adjustable cable, and Mapleshade (a Rogaine candidate if I ever saw oneeach strand of this wire is less than 1/3 the diameter of a human hair).
The Purist interconnect sounded much like their speaker cable, but was perhaps a touch too restrained with the AHT unit. The reasonably priced Raj cables by Pure Logic proved a good match. This silver-coated copper cable has a slider that's used to change the point at which the two negative legs of the wire cross the positive leg, thus "tuning" the cablemuch like setting VTA. Pull the slider one way for brighter sound, the other for duller.
It works! Using the adjusters to lock in the sound, the AHT Phono Stage finally succeeded in sounding sweet on top, a quality that had gone missing in action up to that point in the test period. The Guarneri Quartet playing Mozart String Quartets K.589 & K.590 (RCA LSC-2888), a later White Dog Dynagroove (pre-Dynafloppy, however), sounded utterly sweet and enchanting.
The Mapleshade Omega Mikro interconnect also worked well with the AHT phono stage, especially when their speaker cable was in place, its harmonically full presentation complementing the slightly dry sound of the AHT. Great Jazz Artists Play Compositions of Cole Porter (Riverside RS 93515) was killer with this combo; I regularly blissed out my audiophile pals with the luscious, curvaceous, goosebump-inducing midrange on Herbie Mann's "Get Out of Town."
If you elect to use the fine-sounding American Hybrid Technology Ultra Resolution cables, don't be disappointed at what they sound like at first. Break them in on a Cable Enhancer for at least a week, then be prepared for a continued but slower break-in curve with music. They will sound thin, bright, hashy, and just plain nasty for a time, but this will pass. What you'll wind up with is a loaded-with-copper warmish sound, alive, extended, and somewhat analytic, that mates well with the phono stage no matter the speaker cable used.
When push comes to shove, I'll keep my CAT (at twice the price) for, among other things, the exquisite way it renders human warmth of emotion, as heard when listening to the sublime Harry on Belafonte at Carnegie Hall (LSO-6006). If I wasn't so spoiled by my CAT Signature, I'd swing for this thing in a minute. The overwhelming feeling one gets is that of neutrality, transparency, pace, and faithfulness to the music. "You get what you pay for" still holds true, of coursefor the most part. I think the AHT phono stage's $2500 price is a bargain for the performance offered. You won't easily find a preamp at less than the cost of the CAT with a phono stage like thisespecially these days, when phono sections are becoming but an afterthought in line-stageonly CD engines.
Footnote 3: Combak dots on the main board, Shun Mook Super Passive Diamond Resonators and Mpingo disc, Ensemble Tube Sox, TARA Labs Affinity solid-core power cord, all mounted on an Arcici Isolation Platform/Super Structure rack.Jonathan Scull