Description: Solid state class-AB mono power amplifier, direct-coupled with hand-calibrated, precision balanced input stage. Inputs: 1 balanced (XLR). Outputs: JMF Audio's proprietary gold-plated, 120A-rated, 6mm-diameter LSS terminals (female) and WBT modular gold-plated terminals (male) for spades, wire, and 4mm-diameter banana plugs. Rated output power: 300W into 8 ohms (24.8dBW), 500W into 4 ohms (24dBW), 850W into 2 ohms (23.3dBW). Maximum output current: 112A. Minimum load impedance: 1.5 ohms recommended, tested down to 1 ohm; intentionally limited for amplifier and loudspeaker protection. Input impedance: 20k ohms. Interference rejection: 100dB typical, based on psychoacoustic criteria. Monitoring: Input offset, overload, over temperature, level metering (–15dB–+3dB), deactivatable. Frequency response: 3Hz–20kHz for 250W into 4 ohms, ±0.1dB; –1dB at 100kHz for small signals. THD+N: <0.01% at 250W into 4 ohms, 1kHz; 0.001% typ. unloaded. S/N ratio: 110dB typ., unweighted, 20Hz–20kHz. Damping factor: >1200 wideband with an 8 ohm load.
Dimensions: 19" (482mm) W × 5.9" (149mm) H × 21.2" (539mm) D. Weight: 75lb (34kg).
Finish: Rose-gold engraved, silver or black anodized aluminum enclosure in Orose Silver or Black.
Serial numbers of units reviewed: 311732, 311733. Designed and built in France.
Price: $77,000/pair. Approximate number of US dealers: 9. Warranty: 5 years parts and labor.
Manufacturer: JMF Audio, 228 Voie des Chartons, 88650 Anould, France. Web: jmf-audio.com. North America and UK distributor: Audio Skies, Los Angeles, CA. Tel: (310) 975-7099. Email: info@audioskies.com. Web: audioskies.com.
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COMMENTS
Nice to see a linear amp review back on deck.
JMF specifies 300W-8ohms, 500W-4 ohms, 850W-2 ohms (this says to me bi-polar)
JA measurements: 310W-8ohm, 515W-4ohm, 760W-2 ohms (this suggest mosfet taking an almost 100w dive into 2ohms, regardless of just 3vac line drop)
Cheers George
Looks like Bi Polar not enuff class A bias for MOSFETS ..!
Regards
When was this changed from 33% of rated output to a 1/8 ..?
When was this changed from 33% of rated output to a 1/8?
The 1/3 power pre-conditioning had always been unpopular with manufacturers as it required large heatsinks, so in 2000 the FTC revised the pre-conditioning requirement to cope with the advent of multi-channel class-AB amplifiers - see my report on the FTC's "Amplifier Rule" at www.stereophile.com/content/ftc-proposes-eliminating-its-amplifier-rule.
I continued using the 1/3 power pre-conditioning for many years, but fairly recently adopted the revised FTC test. I now only apply the 1/3 power test when an amplifier remains cool with the 1/8 power testing.
John Atkinson
Technical Editor, Stereophile
... a pair of power amps in order to attain a state of "bliss" when listening to music reproduced by Harbeth 40.3 XD speakers?
Harbeth's US distributor (as well as a retailer) might well want you to believe so.
However, you might want to know which amp Harbeth's owner/designer Alan Shaw uses at UK hi-fi shows to best demonstrate his company's products.
He has bought and uses Hegel H360/H390 integrated amps. The H390 presently sells for a mere $6,600.
Further note that Mr. Shaw has indicated that a peak power output of about 150W (@ 6 ohms) is likely to be sufficient for most home listeners using his speakers. A Hegel H190 is capable of about 225W continuous and about 320W peak (@ 6 ohms), and is now available for only $2,800.
If JVS observed that the -12dB indicator illuminated only briefly, and the -9dB LED never lit, then he was using, at most, about one-tenth of the maximum output power of which the JMF amps were capable - so, well under 100W. While the H190 would meet that requirement, it would struggle with the 1 ohm EPDR of the Alexia V speakers; however, the H390 would handle it with relative ease.
I was expecting your cost analysis the first day this review dropped. Now do the Luxman!
... that Luxman integrated amp was recommended to Alan Shaw, he deemed it to be too expensive, so instead he bought the cheaper Hegel units.
(Plus, he was under the incorrect impression that Hegel products were made in Scandinavia.)
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