• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Audio Research SP-3-A-1 modified.........

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Hi, I own an Audio Reseach SP-3-A-1 that was modified when I purchased it. The changes would appear to be the CAE (Cureio Audio Engineering) modification instructions for changes available over the web. The connections are (I assume) correct because it does play. The work is extremely slopply and I want to reverse engineer the thing and restore the bass, treble, and contour controls. Two tubes (V7 and V8) for the tone control circuit are pulled. Now, I'm wondering if that if I just plug 12AX7's back in if I'll have tone controls, or were all the preceeding changes in steps 1-10 also affect the tone controls. If so, which changes do I keep and which changes do I put back? Basically I want to end up with the changes to the RIAA, Regulator Circuit, and "Beefed-up" bass response ONLY. I for one think that the tone controls SHOULD be there to use. This is the link to the CAE instruction: http://www.curcioaudio.com/SP-3 Mod Documentation.pdf

Ray Corte
(San Jose, CA)
 
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