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

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

  1. schiit

    schiit SchiitHead

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    If you're having hum from the Vidar, you probably have a ground loop. Vidar is 100% silent in our testing, as long as there is no ground loop.
     
  2. winders

    winders boomer

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    Jason,

    I have an Topaz isolation transformer (.0005pF interwinding capacitance) wired for balanced power plugged into the wall. Plugged into the Topaz, I have a single TrippLite power strip. Into the power strip I have Freya, Mjolnir 2 (off), a MacBook Pro, Eitr, and either Vidar or the Pioneer M-22 plugged in. That's it. Nothing else. I tried with the MacBook Pro running plugged in and using the battery. The speakers are passive.

    Do you see any issues in that setup?
     
  3. schiit

    schiit SchiitHead

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    Have you tried lifting the ground to Vidar? Does the vintage amp have a 2-prong plug? Best to take this private to avoid polluting the thread. Sorry for the derail.
     
  4. purr1n

    purr1n Burned out

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    Just another data point: no hum from Saga / Vidar on the 95db woofers / 108db ORIS horns or 93db Fostex 6" BLHs. Buzzing and noise was an issue with Freya / Hegel H2 on same speakers. I have not tested Freya / Vidar combination yet.

    The Pioneer M-22 is the best solid-state amp I have heard so far. The M-22 limitations have to do with its limited power. Also, the the edges of the attacks are a bit rounded compared to the likes to the Hegel H2, although transients are just fast. No necessarily a negative, just different and a matter of component matching that works.
     
  5. PTS

    PTS Friend

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    Would you say it's the best amp you've *ever* heard, solid state or not , power and price not being a factor?
     
    Last edited: Aug 28, 2017
  6. winders

    winders boomer

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    Jason helped me do some troubleshooting and it appears that Vidar is having an issue with grounds loops in my setup. If I plugged Vidar into power with no interconnects, the hum from the speaker was dramatically reduced. I had to put my ear right next to the mid-range driver to hear any hum. I would note that the M-22 in the same test or when connected to Freya in passive or JFET mode had no hum no matter how close I got my ear to the driver.

    I understand that there will be ground loops even if all devices are plugged into the same wall plug. I thought it was the potential difference between the two grounds that would cause the hum. The whole point of plugging all the audio components in the rack into the same power strip/isolation transformer is to eliminate any difference in potential between the grounds. How would I go about eliminating ground loops further?
     
  7. purr1n

    purr1n Burned out

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    I'll take a good SET transformer output amp, like maybe one built to my requirements, over the M-22. However, I would not feel any level of unsatisactoryness using the M-22 in place of my SET tube amps. This cannot be said of other solid-state amps which I think are exceptional to good such as the Hegel H2, Vidar, Vicent SP-331, JLH69.
     
  8. Garns

    Garns Friend

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    A difference in potential is the mechanism by which a ground loop causes hum but it's not because the grounds of the two units are inherently at different potentials. You have a closed loop mains socket -> Freya -> Vidar -> mains socket, and any nearby electromagnetic field can induce a current in that loop. The resistivity of the cable turns that into a difference in ground potentials which is then amplified by the system. The radiated electromagnetic field could be from other nearby mains cables or from transformers and so have a 50/60hz component which will manifest as the audible hum.

    You could try removing potential sources of EMF from near the loop; or reducing the area of the loop by wrapping the RCA cable from Freya around the mains cable back to the socket, then back along the Vidar mains cable into its RCA input; or try an isolation transformer on the RCA cable; or just stick to something with lower gain like the M-22.
     
  9. Tachikoma

    Tachikoma Almost "Made"

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    Not quite, there was a guy offering a refurbishment service for the M22 for ~$450 I think.

    The M22's parts are fairly straightforward to substitute using modern equivalents, even the transistors, which are just "normal" transistors and not fancy sauce VFETs or something.
     
  10. schiit

    schiit SchiitHead

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    EbTech HumX. Done.
     
  11. murphythecat

    murphythecat GRU-powered uniformed trumpkin

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    bit pricey
    find a local tech. my tech recapped my sony ta707es for 80$ and I paid 80$ for parts
    not msure why youd change the transistors if they are working properly. replace all the electrolytics, resistors that show heat degradation, change the relays if they start acting up.
     
  12. PTS

    PTS Friend

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    That's good to know. I assumed techs had to specialize in a particular amp to know what to test for and what to switch out. I see the schematics for the M-22 are online, would a tech know from reading that what replacement caps/parts to order?
     
  13. murphythecat

    murphythecat GRU-powered uniformed trumpkin

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    anyone calling himself a tech is able to read a schematic :). simply ask him to make you a list of all the electrolytics in the amp. id be surprised if there's more then 25 to replace. have him clean the contacts, make sure the relays work fine and your done. it shouldnt cost more then 100$ + the parts. any tech that would charge over 120$ in time to recap the electrolytic is ripping you off. use elna silmic 2 for all the electrolytic and nichicon kg for the big cans psu caps. your in luck in that the m22 is a power amp, so you dont have a phonostage or tone controls board to recap.
    id ask the tech to measure the ESR of the main smoother caps (the big cans); they may not need replacing but id replace them anyway.
     
  14. Drakkard

    Drakkard Facebook Friend

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    I dont have experience with it, but it is regarded highly by some people I trust.
    I also had a chance to compare my A-0012 to KENWOOD L-08C\KENWOOD L-08M combo, and I liked Pioneer more. There were more vintage stuff, but not that noticeable.
     
  15. PTS

    PTS Friend

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    For those with M-22 amps:

    Do they throw out enough class A warmth to be small room heaters, or is it something you can only feel with your hand 12 inches from the amp? SoCal is hosting a rather brutal heatwave currently, so it's a concern.

    Also wondering how much the M-22 would add to a monthly electricity bill if they're on 12 hours a day (perhaps idling half the time)? I listen to music while I work.
     
  16. winders

    winders boomer

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    The M-22 is a small room heater. Mine is in the shop getting checked over right now. But, if I had it now, it would not be on. It's 110 degrees here now. When I stand next the rack with Freya and the M-22 on and playing music, it is very warm. I am going to love it in the winter.

    Since the M-22 is all Class A all the time, it's hot all the time. Does it idle?? When I get it back from the shop, I will plug it into my "Kill a Watt" to see how much power it draws idle and when playing music at my normal listening volume.
     
  17. msommers

    msommers High on Epipens

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    Have you heard any of the Alephs or XA .5 series by chance?
     
  18. purr1n

    purr1n Burned out

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    Add $15- $40 to your e-bill. Depends what tier of energy wastage you are in.
     
  19. purr1n

    purr1n Burned out

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    Nope or not knowingly.
     
  20. bengo

    bengo Friend

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    @Marvey What do your secret Japanese ninjas have to say about Accuphase amps? Which might be worth trying?

    (I saw the P300 mentioned elsewhere, and it was described as a different league even than M22 - but I place a lot less weight on random impressions than yours, which are usually spot on)
     

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