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California Audio Labs CL-20 DVD-V/CD player Measurements

Sidebar 3: Measurements

Perhaps because it uses a DVD transport, the CL-20 offered superb error correction. It played without a glitch through the Pierre Verany Test CD's track 35, which has a 2.4mm gap in its data spiral, breaking up only on track 36. However, its use of a single CD-compatible DVD pickup meant that I couldn't assess its jitter: the test signals for the Miller Audio Research Jitter Analyzer are carried on a low-jitter CD-R, which couldn't be recognized by the CAL player.

The maximum output from the analog jacks was a fraction of a dB above the CD Standard level…

Conrad-Johnson Premier 18LS line preamplifier

Recording artists can reinvent themselves by crossing over into another style of music. Gloria Estefan, who started with Latin music, crossed over into mainstream pop with great success. Doug Sax, who reinvented the direct-to-vinyl disc and produced outstanding LPs for Sheffield Lab, eventually transferred all of his music to compact discs. Ivor Tiefenbrun, designer of the Linn Sondek turntable, now makes CD players.

Similar changes have occurred in electronics. Audio Research, a leading American manufacturer of tube power amplifiers and preamplifiers, introduced a line of solid…

Conrad-Johnson Premier 18LS line preamplifier Page 2

The 18LS has no On/Off switch. Plugging it into the AC mains puts the unit into standby mode: the standby LED lights up, but the front-panel display is blank and the output is muted. You have to read the manual to discover that pressing the Mute button on the front panel or the remote places the 18LS in operating mode, with previous settings retained. Out of the box, the 18LS springs to life with its level set at "20" and the CD input selected. To put it back into standby, press Mute for two seconds.

The front panel is divided into two main sections. Moving from left to right, the…

Conrad-Johnson Premier 18LS line preamplifier Page 3

The 18LS's lack of a phono stage also required a workaround. I used my trustworthy John Dunlavy MX-10 moving-coil head amplifier to boost the signal from my Spectral moving-coil cartridge, and fed the MX-10's output to either a Margules Magenta FZ47 phono stage or to the phono section of my Mark Levinson ML-7 preamp. I found it more convenient to use the Margules, but the ML-7's phono section was more transparent and provided a broader, more three-dimensional soundstage.

Finally, I had to correct for the 18LS's inversion of phase. As stated on p.8 of the owner's manual, optimal listening…

Conrad-Johnson Premier 18LS line preamplifier Page 4

Gustav Holst's Chaconne (CD, Reference RR-39CD) displayed a deep, wide image, with air around the instruments. Playing the opening Kyrie of Misa Criolla (CD, Philips 420 955-2), the C-J/Quad system portrayed a seamless choral fabric behind tenor José Carreras. And at the end of pianist Anna Maria Stanczyk's performance of Chopin's Scherzo in b-flat, Op.31, from Stereophile's first Test CD (STPH-002-2), I heard Stanczyk's manager's "Well done!" correctly through both preamplifiers: at the extreme left stage.

The Premier 18LS and ESL-989s produced an acoustic illusion of a waterfall…

Conrad-Johnson Premier 18LS line preamplifier Specifications

Sidebar 1: Specifications

Description: Solid-state (FET) preamplifier with remote control, 4 pairs inputs (RCA, unbalanced), 2 pairs outputs (RCA, single-ended), 1 tape loop. Maximum voltage gain: 22dB. Maximum output: 9V unbalanced. Distortion: <0.1% at 1V output, IMD or THD. Polarity: inverted at all outputs. Output impedance: 200 ohms. Bandpass: 2Hz-100kHz (no amplitude limits specified). Noise: ref. 500mV input (20Hz-20kHz): -96dB.
Dimensions: 19" (487mm) W by 3.3" (85mm) H by 15.25" (391mm) D. Weight: 16 lbs (7.3kg).
Serial number of unit reviewed: 3401003.
Price: $3495…

Conrad-Johnson Premier 18LS line preamplifier Associated Equipment

Sidebar 2: Associated Equipment

Analog source: Linn Sondek LP12 turntable with Lingo power supply, Ittok tonearm, Spectral moving-coil cartridge.
Digital source: Krell KRC-28 CD transport, Adcom GDA-700 D/A processor.FM tuner: Day-Sequerra FM Reference Classic.
Preamplification: Krell KCT preamplifier, Mark Levinson preamplifier ML-7A with L-2 phono section, Duntech MX-10 moving-coil head amplifier, Margules Magenta FZ47 phono preamplifier.
Power amplifiers: Mark Levinson No.334, Bryston 14B-SST, Conrad-Johnson MF2500.
Loudspeakers: Quad ELS-989.
Cables: 75 ohm digital…

Conrad-Johnson Premier 18LS line preamplifier Measurements

Sidebar 3: Measurements

With its single amplification stage, the Conrad-Johnson Premier 18LS inverts absolute signal polarity. The input impedance at 1kHz was a usefully high 101k ohms and the maximum voltage gain was 21.9dB. The volume-control steps ranged from 1.3dB at the very top of the range to 0.25 and 0.55dB nearer the center of the range. The maximum indicated volume was "99," but between "99" and "89" only alternate numbers resulted in a reduction of level; ie, "98" and "97" were both equivalent to an attenuation of 1.35dB, "96" and "95" were both equivalent to a further…

Mark Levinson No.431 power amplifier

Although Mark Levinson Audio Systems components continue to be produced, the company's headquarters moved in late 2003 from the Madrigal plant in Middletown, Connecticut, to Harman Specialty's facility in Bedford, Massachusetts. There ML shares manufacturing and sales space with Harman's other high-end lines, Revel and Lexicon.

The ML line of high-end solid-state power amplifiers changed even before the company was reorganized. Beginning with the 400W No.436 monoblock (reviewed in the August 2003 Stereophile, Vol.26 No.8), ML amps morphed into low, flat, rack-mountable chassis…

Mark Levinson No.431 power amplifier Page 2

The No.431's dual-mono design means that the amp has a separate power supply for each channel. Each power supply includes a low-noise, 660VA toroidal transformer and two triple-bypassed, low-equivalent-series-resistance 24,000µF, electrolytic capacitors. Heavy bus bars of oxygen-free copper and high-frequency power-supply bypass components are used to lower the No.431's power-supply impedance. The amplifier can draw 15 amperes at 120V from the mains when driving a 4 ohm load to its full power rating of 400Wpc.

A turn-on circuit prevents sudden thumps and damage to components from the…