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Sunn Concert Lead Foot switch

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  • Sunn Concert Lead Foot switch

    I just finished rebuilding a Sunn Concert Lead (1972 date on driver) I picked up that had suffered two past heat events and wasn't working. It works fine now but it had no foot switch and I'm wondering if anyone has a picture of a Concert lead foot switch they could send me... the pin diagram shows a boost and distortion... with no foot switch plugged in I have the distortion control working as a boost.... the reverb works great without foot switch and grounding plug shuts off reverb... was this a two switch or three switch Foot Switch?? Thanks.
    Last edited by elektron; 05-24-2015, 05:28 PM.

  • #2
    The schematic for the Sunn Concert Lead shows a switchable (ON/Off) Distortion & Reverb.

    Rca jacks I believe.

    Make sure you use shielded cable.


    Not too sure what they mean by Left & Right.

    Click image for larger version

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    • #3

      I have the Music Parts test/schematic tech data which shows PIN 52 Dist Out and PIN 53 Distort Boost (wasn't sure if this was two switches or one) ... I need to map it out since guy I bought from tried fixing and took all wires off boards... I rebuilt power amp board, replaced transistors and CAPS, rewired 3 prong cord correctly, I have reverb working great (replaced two resistors and a transistor) but the distortion looks like it needs the foot switch to work... thanks for the info....


      • #4
        I have wired the foot switch jacks on chassis and the distortion I get when shorted is similar to output tube saturation not distortion overdrive/preamp type.... not being familiar with Sunn solid states is this what I should hear??? This amp is loud and very clean... if I close my eyes I would swear its a tube amp ala Fender.... the distortion mimics tube saturation so I'm confused about some of the YouTube videos touting Sunn Concert and Beta distortion for metal... this is a 1972 silver face -- thoughts? Thanks


        • #5
          OK- I got a foot switch from an old Sunn tube amp and it controls Boost and Distortion.. the Distortion seems to be dependent on the impedance of the speaker cab I plug into.... into a 4 ohm load it has very rich distortion.. into an 8 ohm load the distortion is not inspiring and a 16 ohm load it is more tube saturation type.. the amp sounds best into a 4 ohm cab.....


          • #6
            Just checked the schematics and yes, the Distortion is very mild, they simply overdrive the second FET and not by much either.
            Very similar to what Roland and Yamaha did, by the way.
            None of them is exactly famous for its kller distortion
            Just add your favorite distortion pedal and you'll be fine.

            Randalls, with similar Fet preamp topology and Fendery tonestacks, added Zener and plain diode distortion, *and* current feedback to give it bite.
            Juan Manuel Fahey


            • #7
              Thanks--- I've rebuilt several SUNN tube amps over years but the solid states have never crossed my bench until now... I actually like this one and yes your right about the FET...