Sidebar 3: Measurements
The Rotel RB-960BX was also hot to the touch after preconditioning at 1/3 power. Its input impedance measured 28k ohms, its 8-ohm gain 27.4dB. The output impedance was below 0.04 ohm from 20Hz to 1kHz, and rose just slightly to under 0.55 ohm at 20kHz. DC offset measured 2mV in the left channel, 1mV in the right. Signal/noise (unweighted at 1W into 8 ohms) measured 90.3dB. The Rotel is noninverting, a positive-going signal at its inputs remaining positive at the outputs.
Fig.1 shows RB-960BX's frequency response at 1W into 8 ohms—virtually flat above 100Hz…
During an Audio Engineering Society meeting where a former colleague of mine was giving an arcane technical discussion of the optical considerations of data retrieval from a Compact Disc, a longtime AES member whispered to me: "What happened to the good old days of AES meetings when we talked about things like tape bias and saturation?"
Although I found this quite funny, his reaction exemplifies the quandary of trying to keep pace with the rapidly changing technology of the late 20th century. As the field of audio recording and reproduction becomes more and more sophisticated,…
De-emphasis is passive and switched in by a pair of relays, one for each channel. A second pair of relays mutes the unit by shorting the analog outputs to ground. Output inductors are located on the analog output wires just before the jack to meet FCC radiated-noise requirements. Polypropylene capacitors are used exclusively in the audio signal path. The multi-layer PCB features independent ground planes for digital, and left and right analog audio channels.
Most of the X-32's digital electronics have been condensed into two large programmable gate arrays. These chips allow the designer…
By clocking a data sample through a shift register with four taps, four data samples are created. These four samples are then input to four DACs for conversion to analog. Each DAC receives four different samples at the 8x-oversampling rate performed by the DSPs. The 8x-oversampled data is thus interpolated four more times, creating the final 32x oversampling rate. Finally, the four DAC outputs are summed by hardwiring their current outputs.
In essence, the staggered DAC array linearly interpolates three additional points on the waveform in the analog domain between the seven oversampled…
The X-32's soundstage was superior in width and depth to some less expensive processors, but didn't have the feeling of depth provided by the DSPro Basic. The forward quality noted earlier seemed to push all the instruments toward the front of the soundstage, without a clear delineation in the front-to-rear perspective. There was a slightly closed-in character, without the sense of air and space heard through the 2000 or the DSPro Basic. On the Dick Hyman Plays Fats Waller CD (Reference Recordings RR33CD), the Bösendorfer had a reduced feeling of room around the instrument. Jazz at the…
Sidebar 1: Specifications
Description: Decoding software: DigiMaster. Resampling rate: 32x. Resolution: 18 bits. Power bandwidth (–3dB): DC–20kHz. Passband ripple: none (monotonic). CPU power: 36-MIPS (Million Instructions Per Second). Inputs: two coaxial S/PDIF (Sony/Philips Digital Interface Format), one EIAJ optical fiber. Input sampling rates supported: 44.1kHz, 48kHz. Math resolution: 36-bit. Output buffer: monolithic "sledgehammer" with 400mA peak output current and 1300V/µs slew rate. Output level: 8dBV at full modulation. Channel isolation: >110dB at 1kHz. Interchannel phase…
Sidebar 2: Review System
The X-32 was introduced into my reference system consisting of VTL 225W Deluxe monoblocks driving Hales System Two Signature loudspeakers through bi-wired AudioQuest Green Hyperlitz. Preamps included a Classé Audio DR-5 and the EVS Stepped Attenuator reviewed last month. Other digital processors on hand for comparison included a Wadia 2000, Stax X1t, Theta DSPro Basic, Aragon D2A, Proceed PDP, and the D/A section of a Marantz CD-94. The X-32 was driven by an Esoteric P2 transport, the digital output from the CD-94, and a 48kHz signal from a JVC DAT machine…
Sidebar 3: Measurements
Fig.1 shows the X-32's frequency response. Like the Wadia 2000, the X-32 features a rapidly rolled-off treble above 10kHz, its response being down more than 3dB at 20kHz. Wadia claims that their DigiMaster decoding software optimizes the performance in the time domain rather than in the frequency domain (footnote 1). Wadia feels that the tradeoff involving depressed top-octave response offered by the DigiMaster/Frenchcurve low-pass filter is more than made up for in the transient response. The exact nature of this digital filter is revealed in the X-32's impulse…
DAVID BYRNE,: Rei Momo
Luaka Bop/Sire/Warner Bros. 25990-1 (LP), -2 (CD). Steve Lillywhite, D. Byrne, prods.; Jon Fausty, eng. ADD. TT: 63:43
VARIOUS/DAVID BYRNE: O Samba (Brazil Classics 2)
Luaka Bop/Sire/Warner Bros. 26019-1 (LP), -2 (CD). Todo Mundo, prods. ADD. TT: 50:25
Kind of like "MacGyver," someday there's going to be a TV show called "David Byrne: Musicologist." Or he'll pop up hosting one of those earnest kids' shows on PBS—"Can you say 'gamelan'?" Modern-day Raiders of the Lost Chord like Byrne, Brian Eno, Peter Gabriel, and Paul Simon are hell-bent on global…
As an equipment reviewer, I find it helpful to talk to audiophiles and music lovers about their systems and upgrade plans. Fortunately, Stereophile's computer supplier and troubleshooter, Michael Mandel, also happens to be an avid audiophile. I say "fortunately" because I rarely get a chance to talk to people who put down their hard-earned money for hi-fi components. Instead, I usually converse with equipment designers, technicians, and marketing types, hardly people who reflect the buying public. It is thus a valuable education to get feedback from real-world consumers to find out what kind…
