Description: Solid-state integrated stereo amplifier.
Preamplifier section: Line-level inputs: two pairs balanced (XLR), three pairs single-ended (RCA, optional). Outputs: one pair record outputs (RCA), one IEC AC mains receptacle, one ground terminal. Controller connections: three 3.5mm mini-jacks (IR input, DC trigger out/in), one Mark Levinson Link communications connector, one 6-pin RJ-11 RS-232 port, two 8-pin RJ-45 control ports (PHASTLink-compatible). Voltage gain: 0, 6, 12, or 18dB in line stage (26.9dB in amplifier stage). Volume control range: 72.…
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Sidebar 1: Specifications
Sidebar 2: Associated Equipment
Analog source: Linn Sondek LP12/Lingo turntable with Ittok tonearm, Spectral moving-coil cartridge.
Digital source: Sony MZ-R90 MiniDisc player, Krell MD-1 CD transport, Denon DVD-3700 DVD player, Adcom GDA-700 D/A processor.
Tuners: Day-Sequerra FM Reference Classic, Rotel RH-10, Magnum Dynalab MD-102 with 205 Sleuth RF amplifier.
Preamplification: Krell KBL, Mark Levinson ML-7A with L-2 phono section, Duntech MX-10 moving-coil preamplifier.
Power amplifiers: Mark Levinson No.334, Bryston 7B-ST monoblocks.
Loudspeakers: Dynaudio Contour 3.0…
Sidebar 3: Measurements
A one-hour preconditioning warmup at one-third full power exerts maximal thermal stress on an amplifier with a class-B output stage, and after that hour the No.383 was indeed warm to the touch—but not so hot that I couldn't keep my hand on its heatsink.
The amplifier didn't invert absolute polarity. (The XLR inputs appear to be wired with pin 2 hot.) The input impedance was 19k ohms balanced and 10k ohms unbalanced at 1kHz, both lower than the specified 100k ohms. The tape output source impedance was a low 50 ohms. With the line-stage gain set to "6dB,"…
Small-signal THD was very low over most of the audioband, rising slightly in the top audio octave and into lower impedances (fig.4). The actual harmonic content was buried in noise at reasonable power levels; fig.5 shows that it is fundamentally third harmonic. At high powers (fig.6), the third harmonic rose to a still low 0.05% (-66dB) and was joined by the fifth at 0.01% (-80dB). Intermodulation levels were also respectably low, even just below visible clipping into a 4 ohm load (fig.7).
Fig.4 Mark Levinson No.383, THD+noise (%) vs frequency at (from top to bottom at 4kHz): 4W…
Fig.8 shows the continuous output power with both channels driven into 8 ohms and 4 ohms. (When I tried this test into 2 ohms, the No.383 muted and displayed the message "Amp Fault" on its front panel.) The Levinson comfortably exceeds its specification, giving 145W into 8 ohms (23.9dBW) and 230W into 4 ohms (20.6dBW), both at the standard 1% THD+noise definition of clipping.
Fig.8 Mark Levinson No.383, distortion (%) vs continuous output power into (from bottom to top at 2kHz) 8 ohms and 4 ohms.
Repeating this test with one channel driven using a low-duty-cycle 1kHz…
Back in the early 1970s, the BBC needed a physically unobtrusive, nearfield monitor loudspeaker for use in outside-broadcast trucks. Accordingly, they instructed their design department, which at that time featured such luminaries as Dudley Harwood (the "father" of the polypropylene cone, who went on to found Harbeth) and the late Spencer Hughes (the "father" of the Bextrene cone, who went on to found Spendor), to produce such a model. Thus, not only was what was then probably the finest collection of British speaker-design talent involved in its development, there were no commercial…
Sidebar 1: Specifications
Description: Two-way, stand-mounted, sealed-box loudspeaker. Drive-units: 0.75" (19mm) aluminum-dome tweeter, 4.5" (110mm) polypropylene-cone woofer; both units are magnetically shielded for use in close proximity to a TV set or monitor. Crossover frequency: 3.5kHz. Crossover slopes: third-order, 18dB/octave. Frequency response: 80Hz–20kHz ±3dB at 1m; –6dB at 68Hz. Sensitivity: 82.5dB/W/m (2.83V). Nominal impedance: 6 ohms. Amplifier requirements: greater than 20W. Power handling: 45W program.
Dimensions: 12" (305mm) H by 7.4" (188mm) W by 6.7" (170mm) D.…
Sidebar 2: Review context
Power amplifiers were either a pair of Mark Levinson No.20.6 monoblocks or a YBA 2 HC, while the preamplifier was either the Melos SHA-1 headphone amplifier used as a line-stage, the YBA 2, or the Audio Research LS2B. A Mod Squad Phono Drive EPS amplified LP signals from a Linn Sondek/Cirkus/Trampolin/Lingo/Ekos/Arkiv setup sitting on an ArchiDee table. Digital source was variously a Theta DS Pro Generation III, a Counterpoint DA-10 with UltraAnalog DAC module, a Mark Levinson No.35, or the new Sonic Frontiers SFD-2, all driven by a Mark Levinson No.31…
Sidebar 3: Measurements
Fig.1 shows the Harbeth's impedance magnitude and phase. Apart from dropping to 4 ohms in the upper bass, the value stays reasonably high, implying not too demanding an amplifier load. The sealed box is tuned to 68Hz, a little lower than the LS3/5a; the speaker is fractionally less sensitive. Note the wrinkles in the amplitude trace at 340Hz and 33kHz: the former indicates a cabinet resonance at that frequency; the latter is the tweeter's primary resonance, well up out of harm's way.
Fig.1 Harbeth HL-P3, electrical impedance (solid) and phase (…
John Marks wrote about the HL-P3-ES2 in October 2005 (Vol.28 No.10):
The HL-3P-ES2 ($1595/pair, stands required) is Harbeth's drop-in replacement for the BBC's LS3/5a broadcast monitor (see The Fifth Element," October 2002 and JA's recent essay on the LS3/5a). Stands were the Sound Organisation's sturdy, affordable, 24"-high Z570s, a bargain at $245/pair. Walter Swanbon of Harbeth's US importer, Fidelis, graciously hand-delivered the HL-3P-ES2s and set them up, using some Mortite I had on hand. After hearing about an hour's worth of music, Walter pronounced himself satisfied with the…