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Anyone familier with Gibson Discoverer ga-8T amp??

Discussion in 'Amp Central Station' started by woody961, Jun 22, 2011.

  1. woody961

    woody961 Tele-Meister

    I just picked up the following amp:


    To be from 1962; it is in amazing condition; to include the original manual and footswitch, and an aftermarket cover.

    Anyone familier with these? Tube recommendations? Speaker recommendations? (it has 6bq5's for power tubes/EL84's; 6eu7's for preamp, and a 6ca4 phase inverter tube? And a 12" speaker). I want to get it sounding better---don't get me wrong--it sounds pretty good now----and the tremolo is awesome---but it has the original tubes and I think a tube change would help lots as a better 12" speaker would too....

  2. slider313

    slider313 Tele-Holic

    Jan 6, 2011
    If the amp didn't see much use, as it looks like it didn't, I would leave the original tubes in it. The speaker is a different story. A nice efficent 12" would give the amp a boost in volume. A Celestion Blue or Neo would do. The 6CA4 is your rectifier tube.
  3. electricjr

    electricjr Tele-Holic

    Jan 9, 2010
    woodstock, ny
    Cool amp,
    I can't provide any useful info, but I have the earlier top mounted Discoverer Tremolo, just has vol, tone, trem speed and intensity. I have no idea if it's a similar circuit, but I replaced the original jensen (with a tiny alnico magnet) with a new Jensen Mod 12 35, sounds great and I can dime it with no worries (also weighs virtually nothing). Wish I had a pic of mine, the tolex has been stripped and it's painted brick red- I gig with it for smaller shows and always get questions. I got it for $135 10 years ago and haven't touched anything other than the speaker.
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  5. tcadam

    tcadam Tele-Afflicted

    Jan 12, 2007
    Are you sure it's that old? I always think of the brown Tolex-covered Gibson amps as being more of a mid-60's thing. The early 60's that I've seen have been tweed. Of course we are only talking about a few years so I don't know what it really matters...

  6. uriah1

    uriah1 Doctor of Teleocity

    Feb 12, 2011
    I have a GA20rvt..with 6eu7 and 12au7's...a speaker change ..definitely...but, great amp
  7. Wally

    Wally Telefied

    Mar 17, 2003
    Lubbock, TX
    Nice looking amp. tcadam, that single slant front cab style debutted in '62 or so.
    FWIW, it is hard to be familiar with Gibson amps because Gibson might change the details without much formalization of things...meaning that the first SChematic I found fro a GA-8T confirmed what I know about them. That is that they run 6BM8 power tubes. I dont' know when of ir Gibson changed to 6BQ5/EL-84 tubes, but the ones I have seen run 6BM8 tubes. Two schematics agree. That doesn't mean that Gibson didn't change. IT onlymeans that the commonly available schematics are for the 6BM8 GA-8T's.
    IMho, the first thing to do with any amp of that age is to recap the electrolytics. Then, one can accurately assess what the eamp is doing. WIthout strong electrolytics, all other changes are like pi$$in' in the wind. Something happens, but it isn't necessarily good.(;^)
  8. woody961

    woody961 Tele-Meister

    This particular amp has EL84's and the schematic/manual states so......interesting.....
  9. Wally

    Wally Telefied

    Mar 17, 2003
    Lubbock, TX
    Woody, as I said, Gibson schematics are puzzles unto themselves. I have more than o ne source here with GA-8T schematics that show 6BM8's. THe schematic at Shematic Heaven shows the same scheme I have. This schme is valid for the GA-8T with the rear-mounted controls....the amp that preceded yours in Gibson production. I have other Gibson schematics that have no relationship to a certain Gibson amp of the same model name. IT can be very frustration when dealing with Gibson amps.
    I would love to have a copy of that schematic if there is any way you could get one to me.
  10. woody961

    woody961 Tele-Meister

    Shoot me an e-mail and I wll try and e-mail it to
  11. Wally

    Wally Telefied

    Mar 17, 2003
    Lubbock, TX
    Woody, I much appreciate it. Email is coming....
  12. markr1

    markr1 TDPRI Member

    Jun 26, 2011
    Anyone know of value of these amps? I have one locally listed on Craigslist a 1963 all original with black tolex appears mint and is described as that. The asking price is $400. I don't know if that's a good price or the going price. Thanks.
  13. TNO

    TNO Friend of Leo's

    Apr 25, 2003
    Tubes are probably fine. If it hasn't been done already all the electrolytic caps need replacing and a grounded cord for safety and hum reduction.
  14. ScottJPatrick

    ScottJPatrick Tele-Afflicted

    May 12, 2011
    Stirling, Scotland.
  15. vibrasonic

    vibrasonic Tele-Afflicted

    Only a Gibson is Confusing Enough
  16. slider313

    slider313 Tele-Holic

    Jan 6, 2011
    The later amps with black tolex are not as desireable and IIRC they came out around 1965, so it may not be a '63. I believe there were some circuit changes to these models which changed the way they responded and sounded. If it's mint and you like the way it sounds then $300 would be about right.

    Edit: just pulled up that GA-8T from Evansville. It is a brown tolex '63. It needs a cap job and looks to have a non original speaker.
  17. markr1

    markr1 TDPRI Member

    Jun 26, 2011
    Thank you checking it out for me and yes that is the one in Evansville.
  18. Lonn

    Lonn Tele-Afflicted

    Dec 13, 2007
    Sorry to bring an old thread back but I love this amp. I traded an old Strat body for this a few months ago, never been happier with an amp. 62 Gibson Discoverer Tremolo GA-8T with a 2002 Jensen P12R speaker. Looks like hell but plays like a chorus of angels, as long as someone who can actually play uses it . :lol:


  19. t-luxe

    t-luxe Tele-Afflicted

    Nov 23, 2009
    so. cal
    The stock speakers really suck in these early ''Crestline" amps, and since my
    '63 GA5T only sounds good at higher volumes, I installed a removable ext. speaker jack to preserve the original. I find this amp to be pretty bright, but the trem is gorgeous.

    Attached Files:

  20. teletimetx

    teletimetx Poster Extraordinaire

    Jul 25, 2011
    Houston, TX
    Ext. speaker jack is a great idea. I've got a '63 ga-8t in pretty fine shape. Basic sound is kind of lifeless, but the swampy trem is as good as it gets. Use mine as a practice amp, it's fairly light and easy to haul. ImageUploadedByTDPRI1400601592.806851.jpg
  21. Tatercaster

    Tatercaster Friend of Leo's

    Aug 28, 2013
    Rock Hill, SC
    My uncle has a GA-8T with cream vinyl, four knobs (volume, tone, speed, depth), and iirc, 6BQ5 tubes. Sweet amp! It'd be a toss up between my Princeton 6G2 and the GA-8T for best tone ever.
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