PIONEER M-22 PURE CLASS A AMPLIFIER - rare collectible Start Price USD 800.00 Current Price USD 800.00 Time Left - Bid Count 1 Buy It Now Price - Reserve Price - Start Time Saturday, November 22, 2008 End Time Saturday, November 29, 2008 Location Bartlesville, Oklahoma See more about 'PIONEER M-22 PURE CLASS A AMPLIFIER - rare collectible' Description Pioneer did not traditionally build separate power amplifiers, choosing, instead, to build a line of integrated amps. However, the power amplifiers they did build were among the best in the world and, chief among these, was the very rare Series 20 M-22. Series 20 was Pioneer's vision of a no-compromise esoteric hi-fi system that was still within reach of the audio hobbyist. Produced between 1977 and 1983, Series 20 components were based on simplicity of design, meticulous craftsmanship, and the finest parts available. The M-22 is a pure Class A amplifier rated at 30 watts per channel. Pioneer stated in its Series 20 brochure: "Class-A circuits are used throughout to reduce distortion. If operated in Class-B the M-22 would deliver no less than 150 watts per channel--five times as much--with so-so distortion. The most sophisticated circuit construction yet developed by Series Twenty is reflected here, along with truly first-class parts and components to assure you're getting the real advantages of such design." The M-22 used metallized polyester capacitors and nichrome-vaporized, metal-coated resistors and epoxy circuit boards. Pioneer utilized a dual mono circuit design and component layout, with a massive power transformer for each channel, coupled with two equally large 22,000 microfarad electrolytic capacitors per channel. The left and right channel circuitry was mounted to large die-cast finned aluminum heat sinks. All this was mounted to a rigid die-cast aluminum chassis. What was striking about the M-22 amplifiers was, of course, its appearance. Practically all amplifiers in the late 1970s and early 1980s were fully enclosed by sheet metal on all sides, with a ventilated cover. Pioneer took the minimalist approach, indeed, a purely industrial design approach to the design of this amplifier. All the key components were visible, with the left and right channel components grouped in a mirror image. This really appealed to audiophiles who truly are intrigued by the "innards" of their electronic components. And this is what Pioneer had to say specifically about the M-22's performance: "Not to be overlooked is the extremely wide power bandwidth offered in the M-22: 5Hz to 100kHz, both channels driven, 0.01% THD. Note also that the frequency response is an amazing 2Hz to 150kHz, + 0dB/1 dB at 1 watt, and that the signal-to-noise ratio is a high 106 dB (IHF short-circuited A network." At its full power output of 30 watts into 8 ohms, this amp had no more than 0.01% THD between 10 Hz and 30kHz! Class A indeed! The M-22 has a total of 44 transistors and 66 diodes, for a total of 110 semiconductors. It measures 16.53 inches wide, 6.03 inches high and 14.56 inches deep. Its weight is 48 pounds, 8 ounces. M.S.R.P in the late ‘70s was $790.00. The full specs are given below: Circuitry: Differential drive, 2 step Darlington, Parallel Push-Pull, pure complimentary OCL (Class A operation) Effective output (both ch driven): 30W + 30W Class A, 10Hz~30kHz, 8 ohms Harmonic Distortion (10Hz~30kHz, 8ohms): @ 30W output: 0.01% @ 15W output: 0.005% @ 1W output: 0.005% Intermodulation Distortion (50Hz:7kHz = 4:1): @ 30W output: 0.01% @ 15W output: 0.005% @ 1W output: 0.0005% (!?) Bandwidth (IHF, both ch driven): 5Hz~100kHz @ 0.01% THD Frequency Response: 2Hz~150kHz +0/-1 db @ 1W Input Sensitivity /Impedance: 1v / 50k Ohms Load Impedance: 4~16 Ohms nominal Damping Factor(20Hz~20kHz, 8ohms): 60 Signal-Noise (IHF): 106 db Semiconductors: Transistors 44, Diodes 62 Mains Voltage: 120V, 60Hz Power draw: 240W Dimensions: 16.5"w - 6.0"h - 14.6"d Weight: 48.4 lb I’ve owned this amplifier for over fifteen years and used it to drive my original Quad electrostats for many years before retiring it in favor of the tubed Croft OTL which drives them today. I hate to let the M-22 go but also don’t want it wasting its life away in my closet. Hence this reluctant sale. Two "problems" should be noted: 1) The Power-On light has burned out. Not an overwhelming issue. 2) On start up, one of the power transformers emits a low level hum which disappears in about five minutes as the amplifier comes up to temperature. Otherwise, all is as it should be. Opening bid is a small fraction of current market value and there is no reserve price. Payment (in U.S. Dollars) by any convenient means. Amplifier ships when cash is in hand. Shipping via USPS Priority Mail (2-3 day delivery) is fixed at $65.00 for all locations in the lower 48 and includes full value insurance. Shipment elsewhere is at actual cost. I do not charge for handling or packing. Please do not ask me to end the auction early, or to falsify the Customs value. All questions answered promptly via email. Thank you for your interest. Place a Bid!