Ampeg Reverberocket GS12R Vintage- Reverb Feeding Back

Discussion in 'Amp Tech Center' started by claytushaywood, May 10, 2019.

  1. claytushaywood

    claytushaywood Tele-Meister

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    The reverb on my old ampeg reverberocket 2 gs12r (1966 i believe) was dying out so I bought a replacement tank (I bought the proper tnak for capacitance driven reverb circuits like this amp has) and now the reverb is back to all its glory! but it has wayyyy too much reverb! at about 1/4 of the way up on the dial it actually starts feeding back with a high pitched whine that wont go away unless I turn the reverb knob all the way down for a minute or two.

    if I have the knob just below the position that it will feedback it actually sounds really great and lush. The tank is the MOD 9FB2A1C. I didnt have a circuit problem with the reverb before the previous tank died- so could this be the tank itself?

    I did think the reverb (previous to the last tank failing) was way too bright sounding and I did some mods to counteract that. But just some adding more capacitance in places to lower Low pass filters cut offs and some snubber cap type stuff.

    Any ideas?

    Thanks!
     
  2. claytushaywood

    claytushaywood Tele-Meister

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    I've attached the schematic as a PDF (not sure if it will work) but its the best schematic you can find for the amp
     

    Attached Files:

  3. BobbyZ

    BobbyZ Doctor of Teleocity

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    Any old electrolytics in the amp? If so get them in the trash can.
    Make sure the RCA plugs on the pan are making good contact on the outside part. I've had that cause ear bleeding noise on Ampegs, don't recall if the setting effected it though.
     
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  4. Nickfl

    Nickfl Tele-Afflicted

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    Yep, thats the first place I'd look too. I had a silverface VR with reverb that squealed once you turned it past 1.5 on the dial, ESR on several of the cathode bypass caps was through the roof and once I put new ones in it the problem was solved.
     
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  5. claytushaywood

    claytushaywood Tele-Meister

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    all the electrolytics are less than 6 months old. Maybe the .47 blocking cap before the tank? I'm really thinking its the tank itself though at this point
     
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