When I was a child growing up in Moscow in the 1970s, our pop-musical landscape was dominated by the so-called bards. They were Soviet counterparts to singer-songwriters from the West, and they sang literate, knowing lyrics while accompanying themselves on acoustic guitars. Even the word used to describe them—…
I don't know anyone who, having heard the JMF Audio system at AXPONA 2023—the HQS 6002 dual-mono power amplifier ($40,000; footnote 1) and PRS 1.5 dual-mono line stage preamplifier ($36,000) with Harbeth M40.3 XD speakers—did not rave about the sound. In my show report, I credited the system, assembled by Fidelis Distribution and Audio Skies, with delivering "some of the finestsounding music…
The rear panel is dominated by large, vertical heatsink fins. To their left, top-to-bottom, are the XLR input, JMF Audio's proprietary gold-plated, 120A-rated, 6mm-diameter LSS output terminals designed for JMF speaker cables, then WBT modular gold-plated output terminals for spades, wire, or 4mm-diameter banana plugs. JMF Audio recommends their own speaker cables, but to keep things as simple as possible, I used my usual cabling. Below the outputs sits a ground connection that may be used to link the loudspeaker's shield to the amplifier's case—I didn't need it—and the connection point…
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…
Digital sources: dCS Vivaldi Apex DAC, Vivaldi Upsampler Plus, Vivaldi Master Clock, and Rossini Transport; EMM Labs DV2 Integrated DAC, Meitner MA3 Integrated DAC; Innuos Statement Next-Gen Music Server; Small Green Computer Sonore Deluxe opticalModule; Uptone Audio EtherRegen with SOtM sCLK-OCX10 Master Clock and sPS-500 power supply; Nordost QNet switch and QSource linear power supplies (2); HDPlex 300 linear power supply; Synology 5-bay 1019+ NAS with Ferrum Hypsos linear/switching hybrid power supply; Linksys MR9000 mesh router and Arris modem; Apple…
I performed a complete set of measurements on one of the JMF HQS 7001s (serial number 311732) with my Audio Precision SYS2722 system, then repeated some of the testing with the magazine's APx500 analyzer. I preconditioned the HQS 7001 by following the CEA's recommendation of running it at one-eighth the specified power into 8 ohms for 30 minutes. At the end of that time, the temperature of the top panel was 101.8°F (38.8°C) and that of the heatsink on the rear panel was much higher, at 173.5°F (78.6.1°C). The JMF amplifier has just enough thermal capacity for its…
Setup
Once secured in my audio rack, it was a joy to slide my left hand over the L-509Z's silken casework as my right hand removed the rubbery plastic caps that…
Description: Two-channel integrated amplifier with 4 parallel-bipolar, push-pull, class-AB output stage. Inputs, line: 4 pair single-ended (RCA; Line 1 and Line 2 are "Original high rigidity terminals"), 2 pair balanced (XLR); Amplifier in ("Main In," RCA); Phono, switchable MM, high/low, MC (RCA). Outputs, line: Rec Out, Monitor, Pre Out (all RCA); two pair loudspeaker output terminals with independent on/off switching. Input sensitivity/input impedance, MM phono 2.5mV/47k ohms; MC-H phono 0.3mV/100 ohms; MC-L phono 0.1mV/40 ohms, SE line 180mV/47k ohms;…