Pioneer M-22 Power Amp - Epic Japanese Gear From the Past

Discussion in 'Power Amps' started by Armaegis, Mar 30, 2017.

  1. Vishal

    Vishal Rando

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    @PTS all original output transistors from factory! If you can find some original transistors that would be great, the same transistors were used in something like sansui 771 so you can find them, I actually managed to find original matched pairs just incase I blew an output while rebuilding and testing.

    As dBel84 said you can find other newer modern transistors or ones close to original specs perhaps or modify what you have now but why do that? If you can keep it as original as possible do that instead, I had to replace my filter caps they were shot and replacements were very expensive and didn't fit safely or properly, I did subtle changes not to interfere with it but to slightly improve what I already had, these amps will stand the test of time but you have to service it, change parts, check connections etc.

    Currently mine is burning in and powering a set of refurbished quad ELS 57s being fed by a Krell PAM 5 preamplifier and its bloody wonderful!
     
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  2. Armaegis

    Armaegis Friend

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    That ripple on the underside of the pcb... is that the masking or a bunch of flux residue?
     
  3. Vishal

    Vishal Rando

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    I wasn't too sure myself but that's where my issue was coming from, something ksut wasn't right in that specific area, whether this was due to heat, or just caused my inrush current, maybe a prior issue with the amp who knows.

    Underpinning it solved so many issues and made the amp perform and behave.
     
  4. JeffYoung

    JeffYoung Friend

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    I agree here. I'm building a couple of Naim NAP250 clones: one as close to original as possible, and one with some upgrades to see what the difference is. But even the upgraded one uses only parts available in the late 1970s.

    progress1.jpeg
     
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  5. JeffYoung

    JeffYoung Friend

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    Note: those BDY58s are nice 10MHz parts, but the Naim is semi-complementary so I don't know if there are PNP version of them available or not. And they're probably not that much easier to find either.
     
  6. Armaegis

    Armaegis Friend

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    Did you at least clean your own flux off the board when you were done with your repairs/mods?

    And it's hard to tell just from the photos, but some of those look like cold joints?
     
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  7. Vishal

    Vishal Rando

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    This is the thing with vintage amps and boards especially class a, boards are fragile, solder joints need reflowing etc.
    Just to make sure i went over each component and reflowed the solder, no cold joints for sure, another thing with cleaning these boards you have to use special chemicals other wise you get reactions with the protective coating.

    It's all annoying little things but stuff you may have to deal with, i can safely say that the amp is perfect its done about 35 hours of use, its just nice to know all issues have been sorted and its reliable now.
     
  8. Drakkard

    Drakkard Acquaintance

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    Sooo, one of the power caps on my pio a-0012 decided to die recently, so I'm deciding what to change them for, any recommendations?
    Tech guy who is currently looking into it suggesting installing 4x Nippon KS20133L145 he has at hand, but I'm not quite sure they are good enough for this amp. Also, it does not help that I can't find any info about such model on the official Nippon website. Googling reveals only some shady online shop selling them pretty cheap.
    Suitable Nichikons KG seems to cost about $80 per one, which is a bit high, and I'm not sure it is worth it.

    Is there a middle ground between Nichicons and else? Where is a good place to buy them? The only trusty place I know is mouser
     
  9. skem

    skem Friend

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    It’s a power-filter cap. What you want is very low ESR/ESL and reasonable HF response. Mystical acoustic properties aren’t a concern here, IMO. Key properties, in my preference order, are: 0) meet minimum voltage and capacitance spec, 1) modern production, 2) they physically fit, 3) reasonably low ESR, ESL, and good frequency response, and 4) consider a larger capacitance if all other parameters are met. If the amp gets hot, throw in a high temperature rating at position #3.
     
    Last edited: Jul 28, 2020
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  10. S.D.M.F.

    S.D.M.F. Rando

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    There’s a M-22 on eBay that has not been used, will it still have aged and need work? It is
    $2800
     
  11. skem

    skem Friend

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    The electrolytics will have aged and actually could be worse because regular usage provides “reforming” (see academic thesis linked in my post here.) The rest should be happy, though I’d poke around in it to be sure.

    I would personally change out the orange drops for vintage ERO MKT1813 coupling caps. Huge difference in transparency. I have a few spares, so if you’re interested PM me.
     
    Last edited: Aug 1, 2020
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  12. JK47

    JK47 The Beer Houdini

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    @skem Yes, those are 8ohm Viawave tweeters. I didn't respond, because I wanted to see if you could Sherlock the answer yourself, because I've mentioned them a few times in several posts. You're an extremely smart cookie, and I hate spoon feeding.

    In nearly 5 years I haven't reached a 1000 posts, and try to keep the fluff posts to a minimum. Some people don't get that and clog the useful resource threads full of crap, making sifting through information a real pain in the fucking ass... Not directed at you though.

    I really wanted to let the M-25 run in and the caps to settle before giving a a comparison. I've been using the M-25 for music and TV duties since it arrived (I rock the JBL 4312G for all TV duties 8 days a week). I started using the M-22 again during the iPhono vs Nighthawk vs EC Classic comparo last week. I can say this... The M-25 has the gusto and grip in the low end hands down, but the liquid mids and to die for treble of the M-22 has the overall championship title for sure. Even though the caps used in each refurb are not the same, which could be part of the difference in sound, and I suspect my M-22 does not sound like yours. The M25 does get surprisingly warm as I've mentioned before, probably due to the first few watts being class A before switching over, and TV use probably rarely pushes it into class B. Also using the hot XLR outputs from my DAC converted 1:1 to RCA helps bring some more to the plate volume wise with the M-22.

    I could see myself selling the M25 in the future, but definitely not the Mighty Meme-22...
     
    Last edited: Aug 4, 2020
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