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Heath-Guitar amp mod schematic--what do you think?

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  • Heath-Guitar amp mod schematic--what do you think?

    Okay-- With help from many here, I've got a schematic for my Heathkit A7-E guitar amp. Please take a look and tell me if it looks right. The grounding scheme is from Loudthud, the tone values from PRNDL, most of the rest from the original schematic. I've simply bypassed the first triode, to control the gain, but I'm not sure about the first gain stage I'm using, what the resistors will do.

    Any thoughts are welcome!
    Attached Files

  • #2
    The print appears to be drawn correctly. Only one thing I see. On the first two resistors in the circuit, the 470K one. Change those values to 64 K and 900 K going into the first gain stage. Otherwise, give it a go.

    Gary Moore
    Moore Amplifiication


    • #3
      Thanks-- I had just kept the resistors there as they were in the original circuit, figuring they'd need to change. So the 64K goes in the signal path and the 900K goes to ground?


      • #4
        Yes, 64K in signal path and 900K to ground.

        You could also try it this way to get a little more signal into the first stage.
        Attached Files


        • #5
          I think I'll just try both configurations--easy enough. Thanks for the tips. The hard part now for my first build will be translating this into a layout. The trannies and tubes fit in the original places, of course, but figuring out a workable new grounding layout will be the challenge for me. I have another old tube amp (McMartin PA) that uses a neat and clean looking buss system-- I think I'll try something along those lines.