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Unleash Hidden Power from My Classic Peavey TKO?

Discussion in 'Amps and Cabs [BG]' started by Monterey Bay-ss, Sep 10, 2019.

  1. Monterey Bay-ss

    Monterey Bay-ss Supporting Member

    My old (though new to me) Peavey TKO gets me right in the nostalgia and performs about as expected (and was all the amp I needed at a recent show).

    A quirk has me wondering if I'm getting everything out of it I can, though: with the POST GAIN set around 3 or lower, I can suddenly make things MUCH LOUDER by carefully wiggling that gorgeous blue knob, but it never stays that loud for more than a few notes. At higher settings, no amount of wiggling seems to change anything.

    It's plenty loud for what it is, and I have bigger rigs if I need more, but I have to wonder: Is this thing holding out on me? What's going on here?

    Thank you for any information you can provide.

    Attached Files:

    wintremute likes this.
  2. BogeyBass


    Sep 14, 2010
    actually the driven rail design of alot of peavey amps are quite capable of driving the power amp to its theoretical max.

    Easier or tougher way depending how you look at it is more speakers. if you keep adding speakers and maintain a 8ohm or 4 ohm load the amp is capable of handling you can increase sound pressure limit.

    only drawback is the size and cost and vehicle size you own. to carry around whatever massive amounts of cabinet you wanna buy

    if you could just run a 60 watt head into a 8x10 or 4x15 its actually pretty dang loud. likewise if run in series heck you can run 2 3 or 10 svt810 cabs and hey man 60 to 80 watts would cover a drummer pretty dang good lol

    then again with zillions of old lead sled 200 to 300 watt used bass heads. sky is the limit there too. maybe 4x15 or 8x15 8x10 or any high order of cabbage stacks will be loud loud loud with what snobs call weezy watt amps.
    mikewalker likes this.
  3. Monterey Bay-ss

    Monterey Bay-ss Supporting Member

    Oh, that all sounds like a lot of fun, but I've got a Mesa Buster! Bass 200 and a Peavey Mark IV with a decent 1x15 which get quite a bit louder than this, loud as I expect I'll ever need in the case of the Mesa. I'm just wondering what's going on when I wiggle the POST GAIN knob on the TKO at low settings and get a substantial but temporary volume boost, i.e. would this TKO get substantially louder on its own if it were in tip-top shape or something?
  4. Monterey Bay-ss

    Monterey Bay-ss Supporting Member

    You might appreciate this more than most:
  5. BogeyBass


    Sep 14, 2010
    oh yeah its possible.

    the knob just might be dirty and worn out. i just talked about this earlier with amps i have laying around the house or studio. sometimes if just parked at the same old setting. youll get one good spot on the knob rotation and the rest will be dirty or scratchy. or the opposite everything is good except a little spot on the rotation of the knob is bad

    knob needs to be cleaned or replaced. id have to hear it. could be many other things with the amp. but id guess. common dirty pots/ dirty jacks could possibly be the problem
  6. BogeyBass


    Sep 14, 2010
    lol oh thats perfect.

    We made jokes all the time. if ever endorsed would have no interest in some high tech super amp. we would want as many cheap 30 watt combos they made and pile them sky high. and yes literally like the picture. a massive wall of hum with a zillion cords to jumper them all together.
    its like a dream come true lol.

    guess in that case the magic blue knob could be bad on a few too and wouldn't really matter. i had a peavey basic 60 and i know the massive swell of destruction the pre and post gains can do.
    Monterey Bay-ss likes this.
  7. Monterey Bay-ss

    Monterey Bay-ss Supporting Member

    You might appreciate this more than most:
    Sounds like a more thorough cleaning is in order. I had the “boost” in effect for a longer period just now, so I wonder if it’s just a matter of working some contaminants out.
  8. BogeyBass


    Sep 14, 2010
    kinda for the most part.
    without completly bathing the knob in cleaner. a actual very small squirt that actually gets into the knob and a quick run back n fourth should remove enough oxidation to make it workable. basic can of deoxit laying around is useful to have.
  9. andruca


    Mar 31, 2004
    Madrid (Spain)
    I love TKOs SO MUCH. For some time this (TKO-75 on top of TKO-80 -same amp and speaker, just more wood-) was used at both rehearsal and live, sounded thunderous and saved me from moving a 4x10+15 (or 2x15) stack many times with no significant loss in sound quality, bottom end, and even plain volume (these are LOUD).


    Still have those combos, the 75 is home while the 80 is in a vacation house. Lately I've been mostly using either one of these TNT-150s, or the whole monster "stack".


    No camo wrap on these ones. All of these are Scorpion equipped and have been tuned with metal grilles and defeatable piezo horns.
  10. mmon77

    mmon77 Supporting Member

    Jul 9, 2008
    Southern MN
    That classic Peavey gear is so woefully underappreciated. The very fact that there is so much of it still working today should be a testament to how great it is.

    I often joke with my musician friends that if there were a nuclear apocalypse, the only thing left would be cockroaches and classic Peavey gear.
  11. LewisK1975


    Sep 9, 2019
    Wales, UK
    I'm not sure it's underappreciated, it's just that most of them weigh as much as a black hole. Same for old Trace Elliot gear. Both of those brands can be picked up relatively cheaply in the UK right now..
    Cheez likes this.
  12. wraub


    Apr 9, 2004
    ennui, az
    previated devert
    I recently got an old Basic 40 and am continually impressed with just how good it is. If there's more volume in there, I'd take it (but I'm not sure I really need it).
  13. waveman


    Sep 25, 2008
    Try to pull the chassis out and using electronic cleaner spray and use it on all the pots, especially the one the blue knob is on. Pull the blue knob off and spray the front of the pot the knob is attached to, and anywhere you see a tiny hole on the pot inside the chassis. Essentially the front and back of the pot. Turn the knob while spraying and or in between spraying. If that doesn't fix it, the pot needs to be replaced.

  14. I once had a rig that consisted of a Peavey Combo 300, which I bi-amped with a Peavey Special 130 guitar amp using the built in bi-amp on the Combo 300.
    That thing was insane!
    This was the late 80's and I could damn near get Billy Sheehan's tone using that rig.
    In hindsight, if I'd used a compressor on it I probably could have nailed his sound....
    Monterey Bay-ss likes this.
  15. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Terrible advice. This is a great way to ensure that all of the pots are completely ruined. Once that happens, the amp isn't worth the cost of replacing all of the pots.

    Never ever spray anything down the shaft bushing, the lubricant in the bushing will be washed away from where it's needed and onto where it causes more harm.

    The only generally safe material that I have seen used over many years is a TINY spray (less is more) of DeOxit D5 into the slot where the terminals exit the pot. Nothing else worked as well from what I have seen or tested.

    The number of amps I used to see that would have been an inexpensive repair except for the damn miricle cure-all spray that somebody thought was a good idea because they read it on the internet.
    Charlie Tango, nomaj, wraub and 9 others like this.
  16. fhm555

    fhm555 So FOS my eyes are brown Supporting Member

    Feb 16, 2011
    Get it to an amp doctor.
  17. waveman


    Sep 25, 2008
    Techinically you are 100% correct.

    But I have a few amps that I have done this too and they have been working just fine. From a practical POV, if you have an old cheap piece of HW that is not operating properly and don't want to spend money sending something to a tech and buy parts and want to get a little more life out of it before sending it to the dump, then try what I said. I have three amps in operation after doing this that would otherwise be in the trash pile.
  18. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Or just do it properly, it costs no more and takes no more time.
    DJ Bebop and salcott like this.
  19. micguy


    May 17, 2011
    To the original question.....your description of what's happening strongly implies that volume pot with the blue knob is in the feedback loop of a gain stage - when you wiggle the pot, you're breaking the wiper away from the (most likely carbon) trace, and the resistance across the pot (the wiper is shunting some of that when not on full) goes to the pot value (it gets louder). If it were a typical potentiometer/voltage divider topology, the gain would go to zero when the wiper became disconnected. Assuming I'm right about the topology, the maximum gain you're going to get from that stage is when the pot is wide open - where wiggling makes no difference. So, no, you're not going to get more output by fixing the amp, but if you do fix it, the gain will stay where it's put when it's on less than full volume.

    As to how to fix it, listen to Agedhorse.
    DJ Bebop and Monterey Bay-ss like this.
  20. Element Zero

    Element Zero Supporting Member

    Dec 14, 2016
    Come on Andy. Get with the times bud. “That’s how I’ve always done it” and “it hasn’t backfired yet” are the benchmark for trouble shooting. Just ask the mechanics at my plant. They’ll set you straight.

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