Johnson: We wanted to keep the front panel clean, but we also feel that if you're going to set balance, you want to do it from your listening position anyway. And, of course, the balance function is not an additional control---because the volume control sets each channel's volume separately. There's only one set of switches; what changes are the control instructions. What's interesting is that the microprocessor built into the ART is the same one that used to be in the computers we used to run the business---it's…
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Phillips: I noticed that balance control is offered only on the remote.
Conrad-Johnson's ART preamp offers only single-ended operation, and, as expected from a design with a single gain stage, the output is in inverted polarity. The ART's input impedance (at 1kHz) averaged 12.5k ohms (slightly higher in the right channel, slightly lower in the left), which is high enough not to give source components any drive difficulties. Its output impedance varied somewhat depending on channel and frequency, but it remained in the specified 500 ohm region over most of the band. At 20Hz, however, it rose to 1140 ohms, which means that with power amplifiers offering a low…
Fig.1 Conrad-Johnson ART, frequency response at 1V output into 100k ohms (top trace below 200Hz) and into 600 ohms (top trace above 2kHz) (right channel dashed, 0.5dB/vertical div.).
Fig.2 Conrad-Johnson ART, THD+noise vs frequency with volume control at "66" at 1V output into 100k ohms (bottom) and 600 ohms (top) (right channel dashed).
Fig.3 Conrad-Johnson ART, spectrum of 50Hz sinewave, DC-1kHz, at 1V into 100k ohms with volume control at "66" (linear frequency scale). Note that the second harmonic is the highest in level at -57dB (0.14%).
Fig.4 Conrad-Johnson ART, spectrum of 50Hz sinewave, DC-1kHz, at 10V into 600 ohms with volume control at "66" (linear frequency scale). Note that the second harmonic is the highest in level at -50dB (0.3%).
Fig.5 Conrad-Johnson ART, distortion (%) vs output voltage into 600 ohms (top) and 100k ohms (bottom).
Fig.6 Conrad-Johnson ART, dynamic distortion (%) vs output voltage into 100k ohms (black), 10k ohms (red), and 1k ohm (blue).
Description: Dual-chassis, remote-controlled, tube line stage.
Tube complement: ten 6922 dual triodes.
Inputs: five single-ended on RCAs; two processor loops.
Outputs: two single-ended on RCAs; two processor loops.
Frequency range: 2Hz-100kHz (no limits given).
Polarity: inverts phase. Maximum voltage gain: 26dB. Maximum output: 15V.
Hum and noise: 100dB below 2.5V output.
Distortion at 1V output: 0.25% THD or IMD.
Output impedance: 500 ohms.
Dimensions: 19" W by 3.75" H by 15.25" D, each chassis.
Weight: 50 lbs, total…
LP playback: Linn LP12/Lingo/Cirkus with Naim Armageddon Power Supply, Naim ARO tonearm, van den Hul Frog cartridge; Ekos tonearm, Arkiv phono cartridge.
CD playback: Audio Research CD2, Mark Levinson No.39, Meridian 508-24.
Phono preamplifiers: Conrad-Johnson Premier Fifteen, Linn Linto, Naim Prefix.
Power amplifiers: Conrad-Johnson Premier Eleven A, Krell FPB 600, Mark Levinson No.33H.
Loudspeakers: B&W Silver Signature, Dynaudio Contour 3.3, EgglestonWorks Andra, ProAc Response One SC; REL Studio II subwoofer.
Cables: Kimber KCAG and WireWorld GEI…