Description: FET-based, full-function preamplifier: Input impedance: 47k ohms in parallel with 260pF (phono); 31k ohms in parallel with 100pF (line). Input sensitivity (for 500mV output): 0.48mV (phono); 50mV (line). Overall gain: 60dB (phono); 20dB, phase-inverting (line). Output impedance: 160 ohms.
Dimensions; 19" W by 3.5" H by 13.2" D.
Serial number of unit tested: 300100J.
Price: $1295 (1990); no longer available (2011). Approximate number of dealers: 100.
Manufacturer: Conrad-Johnson Design, 12733 Merrilee Drive, Fairfax, VA 22031. Tel: (…
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Sidebar 1: Specifications
Sidebar 2: System
Analog: Goldmund Studio T4/Koetsu RS 11, Linn Sondek LP12/Ekos/Troika, van den Hul MC2 high output, plus various step-ups.
CD players: Meridian 602–603 and Marantz CD80.
Preamplifiers: C-J Premier 7a, Audio Research LS1, Conrad-Johnson PF-1, and Krell KSP-7B.
Power amplifiers: Krell KSA-80B and KSA-250, ARC Classic 120.
Loudspeakers: Apogee Duetta Signature, Apogee Stage, Quad ESL-63, Spendor SP2.2, and Celestion SL-700.
Cable: custom silver/Teflon.—Martin Colloms
Sidebar 3: Measurements
The PF-1 is ostensibly a moving-magnet design with a confirmed 47k ohm, 260pF input impedance. Normally an input sensitivity of 1 or 2mV is available for an IHF standard output of 0.5V for such an input; the PF-1 delivered a 0.48mV sensitivity and an overall gain of 60dB. This was just sufficient for the loudest "low-output" moving-coils, and was well-suited to the "high-output" types which generally offer somewhat lower levels than the average moving-magnet.
Further consideration of the disc input is worthwhile to help understand the optimum matching…
As explained by Ken Kessler elsewhere in this issue, the English A&R Cambridge company made their name by producing one of the UK's most successful integrated amplifiers, the 40Wpc A60. This neatly styled model was in production for a decade or so and was the basis for a large number of good-sounding but inexpensive audio systems. These days, the company, whose products in the US sell under the Arcam banner, is a major British hi-fi manufacturer, with a product line that includes integrated amplifiers, tuners, loudspeakers, cartridges, and even a CD player. A&R was, I believe, the…
Arcam recommends a two-hour warm-up time before the unit is capable of sounding at its best. I actually left it plugged in and switched on for about 24 hours before I did any serious listening. The following CDs were used for the formal listening tests: Beethoven piano sonatas, John O'Conor, Telarc CD-80118; the HFN/RR Test CD; Mahler Symphony 5, Bernstein, DG 423 608-2; I Was Glad: Cathedral Music by Parry, Hyperion CDA66273; Back in the High Life, Steve Winwood, Island; West of Oz, Amanda McBroom, Sheffield Lab CD-15; and Aerial Boundaries, Michael Hedges, Windham Hill WD-1032.
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Sidebar 1: JA's 1989 System
The fundamental system used to assess the sound of the Delta Black Box consisted of the following: Celestion SL700 loudspeakers, sitting on their own spiked stands well away from room boundaries, were driven by a pair of VTL 100W Compact monoblock amplifiers, and were bi-wired with Monster M1 speaker cable. No active preamplifier was used, all signals being routed through the Mod Squad Deluxe Line Drive reviewed last month and since purchased as a line-level reference.
A Marantz CD-94 CD player was used as the source transport to provide data for the…
Sidebar 2: Measurements
The measured output impedances were pretty much to specification, at 27 ohms (Direct) and 495 ohms (Line), as was the frequency response, which measured –0.2dB at 4Hz and 20kHz, with only the merest hint of ripple in the top octave. Although the maximum output level from the direct sockets was 2.18V, as specified, that from the line-level sockets was a little higher at 1.05V. This is inconsequential, however, the 6dB reduction in output being sufficient to avoid overload problems with some older preamplifiers. As the analog output circuitry uses a DC servo to…
Robert Harley reviewed the Black Box 2 in October 1989 (Vol.12 No.10):
The Arcam Black Box 2 essentially is an upgrade of the highly successful Black Box reviewed by JA last February (Vol.12 No.2). The newer 2 version includes an optical input and has the ability to decode both 44.1kHz sampling rate (CD) and 48kHz (DAT). Dealers can upgrade a customer's original Black Box to 2 status for $150 by installing the optical input board. Arcam claims that the Black Box 2 can accept the professional AES/EBU digital audio transmission format. Technically this is not correct. The AES/EBU format…
Sidebar 3: RH's 1989 System
The system used for evaluating the three components consisted of a PS Audio 5.5 preamp (in Straightwire mode exclusively), Vortex Screen loudspeakers driven by Prodigy OTL tube power amplifiers, and Stax Pro Lambda Signature headphones.
Included in the source material was a live recording I had just made as part of an appraisal of the Nakamichi 1000 DAT machine. I recorded acoustic guitar and acoustic bass duets in a church using tube microphones to fully explore the Nakamichi's capabilities (watch for a full report, as well as a review of the 1000,…
Sidebar 4: Measurements
On the test bench, the Arcam Black Box 2 performed better than the Musical Fidelity Digilog that I also reviewed in this issue in several respects. Fig.1 shows the spectral analysis of the Black Box 2's output when playing the dithered –90dB signal on the CBS test disc. The unit exhibited a slight deviation from linearity, as shown by the amplitude at 1kHz not quite reaching the –90dB level. More revealing, however, is what is present at the output in addition to the signal read from the disc. This test shows the amplitude (vs frequency) of the signal at the player…