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…
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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.
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…
John Atkinson wrote about the Harbeth HL-P3ES-2 in April 2007 (Vol.30 No.4):
I reviewed the original version of this minimonitor in December 1993, and John Marks commented very favorably on the sound of the ES-2 version in October 2005.
A sealed-box two-way, the HL-P3ES-2 (footnote 1) uses two magnetically shielded drivers: a 5.5" (110mm) plastic-cone woofer and a 0.75" (19mm) ferrofluid-cooled aluminum-dome tweeter, the latter protected by gold-colored wire mesh. Both units are rabbeted into the veneered front baffle, which, unlike the BBC LS3/5a's, is not set into the cabinet.…
Sidebar: JA's 2007 Associated Equipment
Digital Sources: Classé cdp-202 DVD/CD player, Ayre C-5xe universal player; Mark Levinson No.30.6, Benchmark DAC 1 D/A processors; Slim Devices Squeezebox WiFi music processor with Apple Mac mini running OSX for media storage.
Preamplifiers: Mark Levinson No.326S, Audio Research Reference 3, Ayre K-5xe.
Power Amplifiers: Mark Levinson No.33H monoblocks, Halcro dm38.Loudspeakers: Revel Ultima Studio, Era Design 4, PSB Alpha B1, Rogers LS3/5a (1978 samples), Stirling LS3/5a (2006 samples).
Cables: Digital: Kimber Illuminations Orchid AES/EBU…
Sidebar: 2007 Measurements
The HL-P3ES-2 was slightly more sensitive than the LS3/5a, at an estimated 83.5dB(B)/2.83V/m, close to the specified 83dB. However, its plot of impedance magnitude and electrical phase angle against frequency (fig.1) revealed it to be a more demanding load, with a minimum value of 3.9 ohms at 165Hz and a combination of 6 ohms and –42° phase angle at 100Hz. (The specification describes it as a nominal 6 ohm load.) The peak of 21.5 ohms at 63.5Hz indicates that the tuning frequency of the sealed enclosure is significantly lower than the Stirling LS3/5a's 81Hz. The…
Some folks claim to have actually seen the legendary Bigfoot, the enormous, manlike beast said to roam the backwoods of the Pacific Northwest. Others have stood in his footprints or plucked foul-smelling patches of hair from trees he has recently passed. A few have gotten close enough to take vague snapshots or shaky video clips of the beleaguered creature. One or two attest to frightful chance encounters with him. His size alone has given rise to rumors that he is dangerous, but no firm evidence has ever been produced to substantiate this.
There is irrefutable evidence of a different…