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TNT bass amps

Discussion in 'Amps and Cabs [BG]' started by Kirk P Brosius, Jan 8, 2012.

  1. Hello all,
    Somebody out here in TB land owns a TNT Bass amp. These all tube amps were hand-made in Venice Beach, CA and used by many SoCal musicians including Canned Heat. BlindOwl is seen at Woodstock using one of Frank's 300 watt versions. I own a recently re-tubed and biased 200 watt version and LOVE IT!!! I've used this amp with an SVT Pro 410 (a loner) and Schroeder 410L (mine) with superb results. Mine has a rare 4ohm/8ohm impedance switch.
    I've been in touch with a fellow TNT owner out there who has repeatedly asked for photos which I now have but, my computer recently had a huge hicup and it lost his address. Bummer!!
    Give me a shout and we'll make the connection.
    Later, Kirk
  2. uh1hhuey


    May 25, 2008
    Kirk did you ever work out the computer issue I would like to see those photos.
  3. Hey uh1,
    This thread was started a while ago but I was able to send the pics off to a fellow "tube-head" here on TB.
    I'll see what I can do for you.
    Do you own a TNT amp?
  4. uh1hhuey


    May 25, 2008
    No I don't own any and I have never seen one. My cousin is married to the son of Frank Cooley who built these amps in Venice,Ca back in the 60s and 70s. The son used to put the chassis together and solder parts then stick the TNT emblem on them. Unfortunately the son and his family don't have a single picture of them working in their garage on these amps. So I was trying to see if I could dig up some photos and owners of these amps and pass them onto the some and his father Frank Cooley. Thanks for any help. Michael
  5. Hey uh,
    Back at ya soon, Kirk
  6. uh1hhuey


    May 25, 2008
    Great can't wait to here back from you. Thanks for replying.

  7. uh1hhuey


    May 25, 2008
    Hello have you been able to dig up anything on the TNT amp yet, it's been quiet in here. Lol. Michael
  8. Catalina_Eddy


    Feb 27, 2013
    Hi folks. TNT amps? I just now am in the process of trying to figure out a rebuild on one. Not much info out there as far as historical data.

    The head I've got is rough on the inside. Might have been modded but pretty much true to a bassman design except 4 EL34's in the power section. One 12AX7 pre & the same for the phase inverter. One channel bass amp.

    Attached Files:

  9. Thanks for sharing those photos Catalina_Eddy, I've never seen a TNT amp before :thumbsup:
  10. stonehenge


    Apr 8, 2011
    Duvall WA
    I just found a TNT amp, tough to find out anything about them, mine is missing power tubes, I assumed they were 6l6's but not sure, how would I know for sure? ImageUploadedByTalkBass1409696238.080276.jpg
  11. wmhill


    Aug 20, 2012
    upstate NY
    MTD basses endorsed artist Bartolini pickups emerging artist TECAMP bass players gear endorsed
    and I thought this was gonna be about those 10 ton, toneless tubs of mud, combos from Mississippi ! These actually look cool
  12. Hi.

    :D quoted for the truth.

    You forgot unreliable from the list IME though ;).

    True as well.

    wmhill likes this.
  13. Catalina_Eddy


    Feb 27, 2013
    Nice one, Stonehenge. THe one I've got either has been modded from an original version, like yours, or it was designed with just a bass channel. Opinion leads towards mod.

    That said, the tubes that are in mine are EL34's. 6L6 & EL34's are both octal but, interchangeability relies on the amp & how it's put together. While 6L6's don't use pins 1 or 5, the EL34 uses pin 1 as grid suppressor . You really have to look at how it's wired together & run it by an 'amp guy' (I know just enough to be in trouble). Bias, heater current & a few other aspects come into play.

    For a schematic, a suggestion (since I've found none) was suggested to me on another forum as posted below. Mine was/is a Bassman clone that resembles the Bassman 100 w/o the master vol or clean circuit. The Super comes close too.
    And lastly is the schematic that I drew up of the one in my possession, done on a CAD app that I am not familiar with & as correct as I can get it for now. Again...this is a 4 ea EL34 power tube, 1 12AX7 pre & one 12AX7 in the Phase Inverter slot.

    Hope this helps some. Else, Google the heck out of Bassman 100 mods and/or check out some power tube data sheets.;)

    Attached Files:

  14. stonehenge


    Apr 8, 2011
    Duvall WA
    Thanks Catalina Eddy, this is helpful stuff! I have taken it to an amp tech and should know more next week!

    Sent from my iPad using TalkBass
  15. Catalina_Eddy


    Feb 27, 2013
    Cool then. I'd be interested to hear your tech's take on that amp.
  16. If Catalina's schematic is accurate there are a few small changes I'd suggest for quieter and more reliable operation of the output stage.

    1) Repeat the bias AC supply network, 220k, 22K and rectifier, from the other side of the HV secondary. Connecting the negative ends of the rectifiers will run the bias supply full wave instead of half wave. The ripple frequency will be 120Hz and is smoothed more easily. BTW that HV winding has a centre tap not shown that should go to ground.

    2) Disconnect both EL34 G3 pins (1) from ground. connect them together and wire to the raw bias supply (top of balance control).

    A better value for the EL34 G2 resistors would be 1KΩ 5W WW.
  17. Catalina_Eddy


    Feb 27, 2013
    Thanks for the suggestions, BassmanPaul. My omission on the PT ctr tap. On my example it is routed to one side of the standby switch, thru which it is grounded for normal operation, or open-line in the stby position. Strange but there it is.

    This amp head I have had been sitting in storage 30-40 years. I would not place any $$$ on this being original as it appears to have been worked on with either spare parts or heavy hands. Crude cut eyelet board, lots of bent leads & splices in components, etc. My schematic just represents what's there today. Definitely a Bassman clone in a SVT-looking cabinet.

    If I had a unit that was in as nice a shape as the one Stonehenge posted, I might consider restoring mine to original. As it is, I'm leaning towards keeping 'original' appearance & rebuilding as a AA165 Bassman. For home recording, a 50w bass amp that I can also cross-channel jump for guitar (and attenuate) sounds like a good thing. Still pondering the possibilities though. And still curious if there are many more of these out there.
  18. That's a standard way of wiring a standby switch. I personally am not a fan of that method as it just as effectively turns off the bias supply. When switching the amp out of standby you have hot tubes running with low bias until the bias supply drops to the correct value. This causes stress in the outputs leading to shorter life. A better way is to wire the standby switch to disconnect the output tubes cathodes from ground. This switch should have a resistor wired across it to keep some current flow through the tube. I've found that a 10KΩ 2W works well for this.
  19. Hey all,
    Nice to see that this thread and interest in TNT amps are still alive here.
    I've sent a few pics of my 200watt TNT to "uh1hhuey" (hi Michael) and I'd be happy to post them here if anyone is interested.
    My amp looks very much like that posted by "stonehenge" above.
    Stonehenge; find a savvy tube tech and re-furb that powerhouse. You'll be pleased.
    Take a look in the rear and see if the output trannys are the same color. When Frank built mine, I was told that the matching, lighter colored units were in the 300w versions and the mis-matched units (in mine) produce 200w.
    Mine's going to our next patio gig at The Palisade Brewing Co. (in Palisade, CO) on Oct. 4, it's first outing in 15 years. It has been at least that long since re-tube and bias.
    Later, Kirk
  20. stonehenge


    Apr 8, 2011
    Duvall WA
    Thanks for the info Kirk! Mine is currently at the repair shop, looking forward to getting it back and hearing what it sounds like!

    Sent from my iPad using TalkBass

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