Digital Source: Ayre Acoustics CX-7e CD player.
Preamplifier: Convergent Audio Technology SL-1 Renaissance.
Power Amplifier: Audiopax Model 88 Mk.II monoblocks.
Loudspeakers: Avantgarde Uno Nano.
Cables: Interconnect: Nordost Quattro Fils. Speaker: Nordost Valhalla. AC: PS Audio xStream Power, TARA Labs Decade.
Accessories: PS Audio Power Plant Premier power conditioner; Arcici Suspense Rack, PolyCrystal amplifier stands; Furutech RD-2 CD demagnetizer.—Robert Deutsch
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Sidebar: RD's Associated Equipment
Adcom is one of those companies that's just too consistent for its own good. Year after year, they put out well-engineered, fairly priced gear, while we audiophiles become jaded and almost forget they're there... You want a good-sounding CD player that doesn't cost an arm and a leg? [Yawn.] Well, you could try Adcom. Need a power amplifier with some sock that won't make your tweeters crawl down your ear? There's always Adcom.
To break through our complacency, Adcom would have to produce an outright unlistenable turkey—or a product that raised the bar so high that any audio manufacturer…
Life is short, the art long . . .
You'd think that designing a preamplifier would be simplicity itself, especially in these days of line-level sources. But the truth is, getting rid of a preamp's electronic fingerprint hasn't proven that easy—do a bypass test and the difference can be astounding. Preamps, even well-regarded ones, seem to compress dynamic range, muffle low-level details, and generally throw one of those much-talked-about veils over the sound. Some digital sources, like Wadia's processors and players and a handful of others, allow you to jettison your preamp, at least as…
You'd think that designing a preamplifier would be simplicity itself, especially in these days of line-level sources. But the truth is, getting rid of a preamp's electronic fingerprint hasn't proven that easy—do a bypass test and the difference can be astounding. Preamps, even well-regarded ones, seem to compress dynamic range, muffle low-level details, and generally throw one of those much-talked-about veils over the sound. Some digital sources, like Wadia's processors and players and a handful of others, allow you to jettison your preamp, at least as…
Sidebar 1: Specifications
Description: Solid-state, remote-control preamplifier switchable to passive attenuator/switcher. Rated main output level: 1V. Frequency response: 5Hz-85kHz, ±0.5dB. S/N ratio: >102dB, A-weighted. Input sensitivity: 183mV balanced, 365mV unbalanced. Input impedance: 94k ohms balanced, 47k ohms unbalanced. Output impedance: 1200 ohms balanced, 600 ohms unbalanced.
Dimensions: 17" W by 4.25" H by 12" D. Weight: 15 lbs.
Serial number of unit reviewed: P751DB 01896.
Price: $1250. Approximate number of dealers: 400.
Manufacturer: Adcom, 10 Timber Lane,…
Sidebar 2: Associated Equipment
LP playback: Linn LP12 Lingo/Cirkus/Ekos/Arkiv.
CD playback: Audio Research CD2/DAC3, Linn CD12 Sondek, Sonic Frontiers Iris 3 transport/DAC 3.
DVD player: Denon DVD-3000.
Preamplification: Linn Linto phono section, Audio Research LS8, Conrad-Johnson ART preamplifier, Mark Levinson No.380S.
Power amplifiers: Accuphase m2000, Audio Research VT200, Cary 805C, Mark Levinson No.332.
Loudspeakers: Alón Circe, B&W Silver Signature.
Cables: AudioQuest Lapis, Madrigal CZ-Gel 1, Siltech SQ-80B G3.
Accessories: API Power Wedge Ultra,…
Sidebar 3: Measurements
I agree with Wes Phillips about the sheer quality of the Adcom GFP-750's construction. One thing that had me confused was that the passive option is selected when the red LED above the switch is illuminated. For some reason, I assumed that the light being on meant that the active stage was engaged. Serves me right for not reading the manual!
Once I got that out of the way, I started to measure the GFP-750. The mute control gave a full mute to silence; the unity gain setting of the volume control in active mode was at the 2:00 position; and the preamp was…
The channel separation was fine, though the crosstalk in balanced active mode (fig.3, top traces) was a little higher than in unbalanced mode (bottom traces). Above 2kHz, both graphs showed a rise in crosstalk due to capacitive coupling between the channels, but this was still less than -60dB below 16kHz.
Fig.3 Adcom GFP-750, Crosstalk (from top to bottom): L-R, R-L, balanced mode; L-R, R-L, unbalanced mode (10dB/vertical div.).
Distortion (fig.4) was very low in both active modes, if a little higher in unbalanced mode and at high frequencies. Despite (or because of?) its…
I have been a proponent of methodical modeling and room analysis as aids in setting up audio systems and rooms. They work hand in hand: Modeling predicts a feasible room arrangement, and analysis, along with careful listening, determines how close the outcome is to that predicted. Of course, there should always be another round of modeling to see if the current setup can be improved with more work. The spiral continues, toward, one hopes, perfection.
Modeling is of particular importance: I like to know whether a room rearrangement is likely to be effective before I try to persuade my…
I found it time-effective to reduce the complexity of the model (eg, remove smaller objects) and the order of reflections (3-4) for the early iterations, at which point the number of possible speaker and user positions is large—but an 800MHz Pentium III can take 48 hours or more to run even that modest a set of variables. Several simplified runs will tell you which arrangements deserve more investigation. After that, you can limit the range of positions for speakers and listener while progressively increasing the number of reflections and adding more feature details, as a confirmation of the…
Sidebar: Specifications
Description: CARA Computer Aided Room Acoustics program, Release 2.0. Requires MS Windows. Price: $49.95. Manufacturer: ELAC Technische Software GmbH, Kiel, Germany. Web: www.cara.de. US distributor: Rhintek, Inc., Columbia, MD. Web: www.rhintek.com/cara.