PIONEER Series 20 M-22

[MacGyver]

i personally DO NOT care at all for this amp, as it is much to much of an "Experimental Breadboard" look for me. still, i thought you old codgers would get a thrill out of it...

(NOT, AND NEVER WILL BE IN MY POSSESSION)




http://i291.photobucket.com/albums/ll310/shaorin-chan/PIONEER/M-221.jpg

http://i291.photobucket.com/albums/ll310/shaorin-chan/PIONEER/M-223.jpg

http://i291.photobucket.com/albums/ll310/shaorin-chan/PIONEER/M-225.jpg




http://i291.photobucket.com/albums/ll310/shaorin-chan/PIONEER/M-222.jpg

http://i291.photobucket.com/albums/ll310/shaorin-chan/PIONEER/M-227.jpg

http://i291.photobucket.com/albums/ll310/shaorin-chan/PIONEER/M-224.jpg

http://i291.photobucket.com/albums/ll310/shaorin-chan/PIONEER/M-226.jpg

[MacGyver]

Pioneer M-22 pure Class A 30W per channel stereo 2 channel power amplifier. This is the pentultimate PIONEER acheivement in their quest to deliver true audiophile equipment. The specs on this unit are out of this world...

The M-22 (Class A)/ M-25 (Class AB), Exclusive M3 / M4a / M7(Japan domestic only), M-90 / M-91(last of the over-engineered units), and the SPEC series are the series that are both great sounding and are highly collectable. Of those, the M-22 is no doubt the best sounding and most musical of them all, best only by the impossible to get and insanely expensive Japanese domestic model Exclusive M series. Pioneer states 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 asssure you're getting the real advantages of such design."

"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 all the way!

M-22 uses metallized polyester capacitors and nichrome-vaporized, metal-coated resistors. Pioneer utilized a dual mono circuit design and component layout, with a massive power transformer for each channel, coupled with two large 33,000 microfarad electrolytic capacitors per channel (66,000 total microfarad per channel)!!!. The left and right channel circuitry was mounted to large die-cast finned aluminum heatsinks. All this was mounted to a rigid die-cast aluminum chassis.

Since the unit has been rarely for the last 29 years, all non ceramic capacitors were recently replaced. This includes the four huge expensive and hard to find 33000uf capacitors. All of the replacement capacitors were sourced in Japan with assistance from Pioneer and imported directly. A US based local Pioneer technician was used to replace the capacitors and perform tolerance, bias and spec check on the rest of the components. All in all, a total of 34 capacitors were replaced regardless of their existing condition. The unit currently has a total of about 100 hours on them.

Cosmetic condition:

Inside: As the pictures show, there is No discoloration, no oxidation, paper based stickers are not yellow. There is no dust, no gum, no grease, and no dirt anywhere inside the system. ALL of the connector pins of both of the power modules have been cleaned, polished, and detoxed.

Outside: The unit is about as nice as you will ever find. That does not mean that it is flawless! The Speaker jumpers came with clear plastic knob covers which have degraded due to age. There are some chips to the dark finish beneath the Cast aluminum rim. The Black heat sinks have nor chips or dings (like most of these amps do). So, while this unit is not completely flawless it is without dust, grease, dirt, or gum. Judging from a collector stand point, there are some small marks on the back of the unit that is visible when a strong light is casted that the camera is unable to pickup. All the connectors, indicators, lettering, and power cord are free of marks or scratches.

To anyone that is not familiar to Class A amps: please never put this unit in an enclosed cabinet. There is a tremendous amount of heat being generated by this amp (120 F!!!). It should never be stacked or enclosed. Place in an open style cabinet with at least 10 inches of free space above the unit.

Key Specifications of M-22:

30 watts continuous per channel min. RMS @ 8 ohms, Class A operation, input sensitivity 1V/50Kohms, Frequency response 2hz-150Khz +/- 1db, damping factor 60, power consumption 280 watts, input voltage 120V 60hz only, net weight 48lb 7 oz

[Acoustic]

i personally DO NOT care at all for this amp, as it is much to much of an "Experimental Breadboard" look for me. still, i thought you old codgers would get a thrill out of it...

(NOT, AND NEVER WILL BE IN MY POSSESSION)

Have you ever heard that amp?

[MacGyver]

i am sure it sounds absolutely fantastic, but it just isn't something i'd want to lay eyes on on a daily basis. to each their own...

[Acoustic]

i am sure it sounds absolutely fantastic, but it just isn't something i'd want to lay eyes on on a daily basis. to each their own...

But.. you never have hear the amp, correct?

[MacGyver]

Correct....

[stuwee]

I told John in a PM that it's a crap shoot, when it craps out, you have a doorstop, I happen to like the looks, but, I like SAE's industrial look, It's loaded with unubtainiums from the Trannies to the IC's, I heard one years ago, at a shop, don't recall the system it was used in for the demo, nothing must have stood out,IMHO, or I would have remembered it, Dale the EE said it's nice if it works but, whatcha gonna do if it don't??

I've been able to hear diffs in amps since I started buying systems back in the late 70's, I always disliked Stereo Review because, Julian Hirsch said nobody could hear the diff in a A/B or even C blind test, I'm not sure my tests at my many homes and speakers is a good enough test however, I can tell the diff in the 4 amps I use and swap in and out regulary, even with run of the mill interconnects too. I would like to give the Pioneer another shot with the 'Logans or even my very warm and musical AR's for that matter. The unubtainium parts give my pause at anywhere near what these babys command when they come up for sale.

Anyone care to buy one and let me test it...*eyepop* I'd be happy to eat my words. I really don't recall it standing out.
Craig

[Acoustic]

Stew, I've got three Yammie's that are switchable Class A/B. For me, it really depends on the music you listen to in Class A to hear the difference. Where Class A shines, for me, since the power is biased on, if your listening to music with dynamics... it will startle you. Like on Pat Metheny's Question Answer the snare pops hit you hard. Clarity in piano solo's, that are well recorded are... there in the room with you (I can just imagine what the would sound like on your Logan's). You will not hear any/much difference at all with dance or pop music or even rock.

http://farm3.static.flickr.com/2008/2114268214_6963144017_o.jpg

Two of them are 30w 8ohms and the other is 15w in Class A. Mine run at 135-140f. You can see my instant read thermometer on top... and if the amp fries...like you all said.... it's a doorstop. But I'll take my chances.

[stuwee]

Acoustic, first, *drool*ly Yammies, I think you misunderstood me, the class A Yamaha's can be fixed, the Pioneer can not. I'm familar with the Yamaha's you have, the one I have can't be described as class A, some say it is, some say it isn't, even Yamaha's info is vague, it definately is not switchable, it's kind of a new fangled version called hyperbolic drive (goobly-gook) *dunno* I just know it has that sound even at high output levels *eyepop* I know Yamaha's have always run hot even in A/B, mine runs barely warm, the technology has moved forward apparently, and the Pioneer amps like the 20 series has been left behind as have many other nice pieces.