Listening
Although it's difficult to say for sure without a blindfold and some 15-second snippets of unfamiliar music, it seemed to me that the Air Tight ATM-1S and my Shindo Corton-Charlemagne monoblocks, both of which use push-pull EL34 pentodes as output tubes, shared some common sonic and musical characteristics. Both were colorful, well textured, and slightly warm and lush,…
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A final setup note: It didn't sound to me as if the ATM-1S inverted absolute signal polarity, but I've been wrong about that sort of thing before. Let's see what John Atkinson's measurements uncover.
Sidebar 1: Specifications
Description: Tubed stereo power amplifier. Tube complement: four 6CA7/EL34, two 12AU7, one 12AX7.Inputs: 2 line-level. Output power: 36Wpc into 8 ohms (15.6dBW). Input sensitivity: 1V. Input impedance: 100k ohms. Output impedance: 4 and 8 ohms (see text). Frequency response: 20Hz–20kHz, ±1.0dB. THD: <0.1% at 1kHz, 1W; <1.0% at 1kHz, 36W. Signal/noise: 100dB (IHF-A weighted, input shorted).
Dimensions: 14.4" (368mm) W by 9" (231mm) H by 11.4" (293mm) D. Weight: 48.4 lbs (22kg).
Serial number of unit reviewed: 19046.
Price: $9500. Approximate…
Sidebar 2: Associated Equipment
Analog Sources: Garrard 301, Thorens TD 124 turntables; EMT 997, Thomas Schick tonearms; Ortofon SPU-A, Miyajima Premium BE Mono II, EMT OFD 15 & OFD 25 & TSD 15 70th Anniversary pickup heads.
Digital Sources: Halide Design DAC HD USB D/A converter; Apple iMac G5 computer running Decibel 1.2.11, Audirvana Plus 1.5.12 playback softwares; Sony SCD-777ES SACD/CD player.
Preamplification: Hommage T2 step-up transformer; Shindo Masseto & Allegro preamplifiers.
Power Amplifiers: Shindo Corton-Charlemagne monoblocks & Shindo Cortese, Fi…
Sidebar 3: Measurements
I performed a full set of measurements on the Air Tight ATM-1S, using my Audio Precision SYS2722 system (see www.ap.com and the January 2008 "As We See It). Before I did any testing, I let the amplifier run for an hour with a 1kHz tone at 1Wpc into 8 ohms, then turned off the input and checked that the bias current for each of its four output tubes had been correctly set. I used the rear-panel inputs for the testing, and repeated some tests using the front-panel input jacks to see if there were any differences. There weren't.
As Art Dudley surmised, the…
Can a power-supply upgrade produce audible sonic benefits? If you've upgraded the power supply of a phono preamplifier, you probably don't need to be convinced that it does, and those usually cost only a small percentage of the price of the model they power. But to add Simaudio's Moon Evolution 820S power supply ($8000) to the Moon Evolution 650D DAC–CD transport ($9000), which I reviewed in the November 2011 issue, almost doubles the latter's cost—though the 820S can be used to simultaneously power two Moon Evolution components, like the 750D DAC ($14,000), 740P preamplifier ($9500), and…
Adding the 820S immediately produced a substantially improved and more inviting sound that, rather than to dissect and analyze, I just enjoyed and chalked up to "improved listenability with fewer digital irritants." And after living with the 820S for a few months, removing it made the differences even more pronounced—glaringly so.
In general, adding the 820S tightened the bottom end and removed smear and edge from the top, while improving high-frequency extension and the sense of air around instruments. Instrumental three-dimensionality improved, and microdynamics were particularly…
Sidebar 1: Specifications
Description: Outboard power-supply upgrade for selected Simaudio Moon Evolution models. Transformers: two, 0.25kVA each. Total capacitance: 80,000µF. Total inductance: 80mH. Output voltages: ±20V (analog supply, output 1), ±14V (digital supply, output 2). Power consumption at idle: 25W. AC power requirements: 120V/60Hz or 240V/50Hz.
Dimensions: 18.75" (480mm) W by 4" (103mm) H by 16.81" (431mm) D. Shipping weight: 40 lbs (18.2kg) shipping.
Serial number of unit reviewed: P8823170.
Price: $8000. Approximate number of dealers: 80. Warranty: 10 years,…
Sidebar 2: Associated Equipment
Analog Sources: Continuum Audio Labs Caliburn turntable & Cobra tonearm & Castellon stand; Kuzma 4Point tonearm; Lyra Atlas & Etna, Ortofon Anna & Transfiguration Proteus, Miyajima Labs Zero (mono) cartridges.
Digital Sources: Simaudio Moon Evolution 650D DAC-transport; BPT-modified Alesis Masterlink hard-disk recorder; Meridian Digital Media System; Pure Music, Vinyl Studio music-player softwares.
Preamplification: Ypsilon MC-10L & MC-16L step-up transformers; Ypsilon VPS-100 phono preamplifier; darTZeel NHB-18NS preamplifier.…
It's August as I write this, and I'm looking back at some things that need to be discussed, and forward to the fall audio shows—particularly the 2014 New York Audio Show, which, by the time you read this, will have been held in Brooklyn, September 26–28. I grew up in Brooklyn, not in "the city," Manhattan, a place that we traveled to only for special reasons. Audio shops were rare in Brooklyn—I remember only Audio Exchange—but in Manhattan there was a small cluster near Grand Central Station, there was Lafayette Radio near the Holland Tunnel, a few scattered elsewhere, and the magnet of…
Sidebar 3: Subtle & Not-so-Subtle Changes
During this review I added a variable to the mix: Shunyata Research's new ZTron Alpha Digital AC cable ($995). It's less expensive than the company's top cords, but demonstrably more efficacious for removing power-line noise than some of their earlier, more expensive efforts. Shunyata backed this claim up with a paper-shredder demo at the 2014 Consumer Electronics Show, showing the reduction of AC line noise with an oscilloscope.
Before the 820S's arrival, I'd tried the ZTron Alpha Digital and a stock power cord on the Simaudio Moon…