olegau Posted May 11, 2018 Posted May 11, 2018 Item: Vintage JVC AX-1 class A integrated amplifier Location: Melbourne Price: 120.00 Item Condition: Good, recently refurbished Reason for selling: Too many amps around Payment Method: Pickup - Cash, COD Only Extra Info: The amp is in good condition and working order. Sound clear and detailed. Specifications Power output: 30 watts per channel into 8Ω (stereo) Frequency response: 10Hz to 100kHz Total harmonic distortion: 0.007% Damping factor: 50 Input sensitivity: 2.5mV (MM), 150mV (line) Signal to noise ratio: 73dB (MM), 77dB (line) Output: 150mV (line) Dimensions: 120 x 420 x 329mm Weight: 5.5kg Review: This amp was capable of delivering. Into two Clements TL 'Spatial Image' floor standing speakers, it almost matched my own 40 year old 20 wpc class A amp, inspired by my dear departed old friend, John Linsley Hood, but with slit supplies and two constant current sources defining the standing current, and no bootstrap capacitor This AX-1 was very good. Later, on test, I adjusted the mysterious chip that sets up the current that defines where class A becomes class A/B. Square waves remain remarkably unaffected by being passed though this amplifier, with no visible ring shown on my HP oscilloscopes. The circuit is very stable. The bass falls off rather too soon, which may have more to do with ageing capacitors in the signal path than anything inherent in the design. And then there's the power supply. It is truly massive, and here's some of the secret of the solid sound. It is almost possible to assess the quality of many amplifiers, as also it is for speakers and pianos, by their weight This AX-1 is no pretend class A PSU, despite the sickly 'Super Class A' flash on the front panel. This is the PSU that keeps on giving adequate current and with negligible ac ripple. There was an audible 100Hz buzz from the transformer that would not be negligible if one were sat within couple of feet from the amplifier. But the service manual and cct diagram is available from hi-fi engine, and apart from the magic chip that sorts out the class A/ class AB biassing, there is nothing very other wordly or metaphysical contained within the circuit. You get a LED strip pair of peak meters, loudness control, a very acceptable phono stage and a decent headphone output. This amp had an audible 100Hz buzz from the transformer too but I fixed it. Now the amp is quiet. Pictures: 1
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