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Two Stroke impedance switch problems

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  • Two Stroke impedance switch problems

    Hello folks. I appear to be having a problem with my two stroke amp build that seemingly no one else has encountered. As far as background, I built the two-stroke amp from Dave Hunter's book, using sourced parts from various websites (Weber, TubeDepot, Mojotone). I followed the directions rather faithfully, while also incorporating the tweaks that Dave sent out (I used one 6L6 instead of the 2 6V6's, etc). The build went well and the amp plays like a dream.

    However, I built the amp with two speaker jacks wired in parallel running to a Jensen 8 and Jensen 10, as the instructions illustrate, with an impedance SPDT switch wired according to the book's suggestion (ie. the white and yellow wires). The problem I have is when I switch the impedance switch to the 8ohm setting and unplug a speaker from its jack, the amp gives off a very high-pitched noise and any signal from my guitar is a garbled mess.

    I'm worried that I may be taxing my output transformer, so I have never let the amp run more than a few seconds like this before shutting it down and restarting it with both speakers plugged in. Has anyone run into a similar issue as this?

    Could it be an issue with using a 6L6 instead of a 6V6? The amp kit notes say to use the gray OT wire with a single 6L6 and the yellow OT wire with a single 6V6, but the book states that each is usable with a single 6L6.

    Last edited by johnjabor; 01-15-2010, 08:53 PM.

  • #2
    You all can forget my message. I reread the amp kit notes that discussed the different OT wire colors of the Weber OT vs. the Hammond used in the original prototype. I used the proper wires for the speakers, but I never reversed the blue and brown primaries. Once I rewired this the problem was solved. Can't believe I missed that.