NOS Input Tubes Distort*

Discussion in 'Audio Hardware' started by Captain Vinyl, Oct 12, 2017 at 11:11 PM.

  1. Captain Vinyl

    Captain Vinyl Active Member Thread Starter

    Location:
    Kansas City
    Hi All -

    I recently purchased some matched, NOS output tubes from a reputable tube reseller and they sound quite distorted, especially in the 30-60 HZ range and more noticeable at higher (but not terribly high) volumes.

    Similar to most new tubes I buy, these sound bright, harsh, lack weight, etc... And as in most cases, these characteristics will smooth out after some break-in time. Hence, I'm mostly concerned regarding the distortion. I'm curious if anyone has experienced distortion from new tubes? Will they "smooth out" after some break-in time?

    FYI - There were no issues with the amp prior to installing the new output tubes. I heard some good things about these tubes and wanted to experiment with them.

    Thanks,
    -Captain
     
  2. vinylkid58

    vinylkid58 Forum Resident

    Location:
    Victoria, B.C.
    What amp, what tubes, and are you able to bias them individually?

    jeff
     
  3. Captain Vinyl

    Captain Vinyl Active Member Thread Starter

    Location:
    Kansas City
    Hi Jeff,

    My amp is a Decware TorII MK4 and it's self biasing (no bias pots). The output tubes are 6922 and the tubes I recently purchased are 6N23P-EV
     
  4. Davey

    Davey very clever with maracas

    I think you meant to say input tubes, which is what the 6922 would be. I think the outputs would be EL34 or KT66.
     
  5. Captain Vinyl

    Captain Vinyl Active Member Thread Starter

    Location:
    Kansas City
    Ooops...Thanks Davey you're right!

    Maybe a gort can fix the thread title for me to Input Tubes.

    @Petrofsk
     
  6. RDriftwood

    RDriftwood Forum Resident

    Location:
    Midwestern US
    It would be nice to know what brand the tubes are... because not all NOS tubes are created equally.

    It would be nice to know if both channels sound distorted. If not, swap tubes to see if the problem is one tube, both, or possibly something else.

    Did you look at the tube pins closely before putting them in the amp to ensure that the tube pins are not corroded and need to be cleaned? I've run into old NOS tubes that needed to have their pins cleaned due to tarnish and/or corrosion.

    Do the tubes feel like they are seated firmly in the sockets and making good contact? Sometimes the pins need to be bent into (or out of) shape ever so slightly to make good contact. (small tubes and pins only - NOT big octal tubes)

    These are the things I would check before doing anything else.
     
    Last edited: Oct 13, 2017 at 1:16 AM
  7. Captain Vinyl

    Captain Vinyl Active Member Thread Starter

    Location:
    Kansas City
    • They are Russian Military Spec - Made at the Reflector Plant in Saratov
    • Both channels are distorted
    • No corrosion noticed on the pins; looked very clean
    • The tubes are seated well
    Thanks for the feedback
     
  8. Captain Vinyl

    Captain Vinyl Active Member Thread Starter

    Location:
    Kansas City
    I failed to mention the tube number:
    6N23P-EV
     
  9. Davey

    Davey very clever with maracas

    Actually you did mention it above, and they should be direct 6922 replacements. I'd do the swap like @RDriftwood suggested, maybe put the stock 6922 tubes back in on one channel and then cycle the new ones through on the other channel and see if there is any change, trying to narrow it down. If you put the original 6922 tubes back in, the problem goes away, right?
     
  10. Captain Vinyl

    Captain Vinyl Active Member Thread Starter

    Location:
    Kansas City
    Correct, the problem does NOT exist with the original 6922 tubes. I will try switching the new/original tubes around and see what happens.

    I'm still curious if tube distortion will subside after some burn-in time.

    Thanks for your comments!
    -cheers
     
  11. Davey

    Davey very clever with maracas

    I would say no, if they were really matched, you would think they were also tested for gas leakage and all the other parameters. Have you talked to the place you bought them from yet?
     
  12. Captain Vinyl

    Captain Vinyl Active Member Thread Starter

    Location:
    Kansas City
    Yes, via email. He stated that they need 50-100 hrs to settle in.
     
  13. Steve Hoffman

    Steve Hoffman Your Host Your Host

    B******t answer.

    Lose those tubes.
     
  14. triple

    triple Forum Resident

    Location:
    Zagreb, Croatia
    Probably more like 100hrs. Like all new tubes, NOS or otherwise.
     
    IanL likes this.
  15. McLover

    McLover Forum Resident

    Location:
    East TN
    What Steve said. Lose the substitute tubes. Get proper replacements.
     
    Captain Vinyl likes this.
  16. Steve Hoffman

    Steve Hoffman Your Host Your Host

    Tubes don't need 50 hours to settle in. C'mon. Try 1/2 hour.
     
    bozburn, DrZhivago and Captain Vinyl like this.
  17. avanti1960

    avanti1960 Forum Resident

    Location:
    Chicago metro, USA
    I know tubes can "stabilize"1/2 hr. after first turning on.
    I can't swear to it but it seems like most tubes I have used seem to round off slightly - become cleaner and less edgy the longer you own them. Not going to turn a buzz bomb into a smooth operator, just some subtle changes. No?
     
  18. Steve Hoffman

    Steve Hoffman Your Host Your Host

    Well, I think you are describing the degrading process.
     
  19. chervokas

    chervokas Forum Resident

    No noisy or distorting tube is ever going to "settle in" and become not noisy and distorted. The only thing that happens with tubes over a period of use is that they being to perform worse, not better -- they weaken. And I've never known a tube to get less noisy over 50-100 hours of use.

    I have used 6N23P's and they can sound really great -- fast, open, detailed -- but I've also had 'em go bad on me in ways that old Amperex 6DJ8's literally never have over decades of use, they go kind of crackly and distorted.

    If you just think the sound is "bright, harsh and lacks weight," there might not be anything wrong with the tubes, you might just not like their characteristic sound -- which is definitely more detailed and less warm than some other classic 6DJ8 type tubes, like Amperex Bugle Boys. But if you're getting distortion in the bass, there's something wrong.

    I know you said you checked that the tubes were seated properly, but I would double check that -- not just that the tubes are pushed all the way down in the socket but that each pin is in tight side-to-side contact with the socket contacts, and that the pins aren't narrower that the pins on the prior tubes or edged in. Some of these newer production tubes don't always have pin widths that are the same as older production tubes, and if one set of tubes has been in a set of sockets for some time and you put in another set with narrower pins, it's possible that contact isn't ideal and you can get distortion, I wouldn't think that would necessarily be frequency-specific distortion, but who knows, maybe you're just starting to notice it first in the bass. Sometimes the sockets need retensioning to accommodate those tubes.

    Other than that, I'd say, return the tubes to the seller, they're not working properly.
     
    Last edited: Oct 14, 2017 at 11:56 AM
    juno6000 likes this.
  20. Lonson

    Lonson Don't get around much anymore

    Location:
    Chardon, Ohio
    I'm not sure that these tubes are always direct replacements for 6922 tubes and perhaps this is a case where they are not compatible.
     
  21. triple

    triple Forum Resident

    Location:
    Zagreb, Croatia
    I said 100hrs, not 50. Also, I was thinking of burn in, not quite sure what settle in means. Those who disagree should have a look here:
    Eight, count them, eight beautiful NOS Mullard EL34 tubes
    No need to read through all of it, posts #1, #27 and #50 will do.
     
    Last edited: Oct 14, 2017 at 1:59 PM
    IanL likes this.
  22. Captain Vinyl

    Captain Vinyl Active Member Thread Starter

    Location:
    Kansas City
    I have sent an inquiry to the manufacturer regarding the compatibility of these tubes in my amp. I've also sent a request to return the tubes to the point of purchase.

    Thanks to all for the feedback.
    -cheers
     

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