Vox AC30 power soak

Discussion in 'Amp Central Station' started by since71, Mar 29, 2020.

  1. since71

    since71 Tele-Meister

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    Dunno about you, but I've had a bit of time on my hands lately so I thought it was time to try to tame my favourite amp, a late 60s AC30, housetrain it, make it usable without incurring the wrath of those nearby.

    I had previously (here's one I made earlier) made a power soak for my Boogie Mk3 incorporating a QPDT switch and 3 x 8ohm resistors wired so that it either went straight to the 8ohm speaker or so that there was a series pair in parallel with one resistor in series with the speaker. The resulting 50% drop was very disappointing, so for the Vox I went for 25%.

    IMG_1337.JPG

    All the bits ready. Notice there are 2 resistors which are 4ohm instead of all the others, which are 8. Could do with some 16s really.

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    Sad to say, even at 25% power its still way to loud for house. I'm assured by no greater authority than the wife that this is the case. Oh well, its a bit quieter.
     
  2. rze99

    rze99 Poster Extraordinaire

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    Hi - also from London

    Great effort. Yeah the AC30s need a hell of a lot of taming to use domestically.

    I've got a late '60s AC30 I bought a used THD Hot Plate for mine many years ago and it sounds great even getting it to very low volume levels.
     
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  3. Jon Snell

    Jon Snell Tele-Meister

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    A tad over the top if you don't mind me saying.
    It's a VOX and they aren't fussed about balanced impedances on the speakers so try this;
     

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  4. since71

    since71 Tele-Meister

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    Also South London. We should open the windows switch on and probably locate each other.
    I've not heard of the THD thing, there are various things available but this is what is in the house.
    I hadn't switched mine on for a couple of years, I've had it since early 80s. I had loads back then for £80 or so. This one I kept, it was a super twin top, very original and I got given a combo cab, I ran for a long time with a single EV. When I put the Blues in I was blown away by the tone. Don't know what happened to the super twin box.
    It does need a good service, clean valve bases and pots and a re-cap but still better than anything else.
     
  5. dan40

    dan40 Tele-Afflicted

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    I built this circuit last year after reading through the thread. There were several design changes throughout the course of the thread but the one listed on the first page is the most recent (last time I checked). Great reactive attenuator circuit that allows me to crank up my Marshall 18 watt and not be heard outside.

    http://www.marshallforum.com/threads/simple-attenuators-design-and-testing.98285/
     
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