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Chip socket to bypass

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  • Chip socket to bypass

    I've got a couple inputs that stock, run too hot/gainy. A Lexicon LXP-1 and a guitar Digitech GSP1101 preamp. Usually the signal is buffered anyways so completely bypassing these clipping-prone chips would be beautiful.
    By dropping in stacked sockets this is possible and reversible. But how to?
    Please draw on this pic if you can.Click image for larger version

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  • #2
    Answer depends entirely on what chip was in the socket, and on the surrounding circuit, and you didn't give any details of either.

    If an op-amp, I'd make an adaptor that reconfigured it as a unity-gain buffer. Then pot it in epoxy, add a dab of gold paint and sell it on Ebay for 40 bucks.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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    • #3
      Oh yeah, its for the standard op amp: TO 072 or LM4562 (upgrade) types. The circuit is an input amplifier but as to what else/schematic, I don't yet know. I could post circuit board pics if necessary, but that would take a while!
      I was just hoping to add a cap/jumper someplace.
      IN--->OUT
      3 to 7 or 5 to 1? Click image for larger version

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      • #4
        You would need to know what configuration it is in (inverting, non-inverting) and whether or not it is even wired to provide gain. The chip you're looking at may already be just a buffer with no gain, so bypassing it won't accomplish anything. Have you scoped the input versus output to see if any gain is actually being applied?
        Without the schematic, it's just a guessing game.

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        • #5
          I don't have a scope. I could record the affected sine wave. (got a sine wav. on the iPod)
          On the Lexicon there is level pot after so it's likely boosting level.

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          • #6
            Bypass nothing.
            Don't mess with this żamp? about which we do not know nothing.
            Just pad the "too hot output" of your Lexicon and Digitech.
            Start with a 47K/4K7 voltage divider.(10:1).
            You may even put them inside a plug of your (dedicated) cable if you use 1/8 Watt resistors..
            EDIT: 3 to 7 and 5 to 1 will turn it into an AM transmitter (more precisely a CW one), frequency around 3MHz (or whatever actual bandwidth that specific chip has), which being squarewave will have a lot of harmonics and make life miserable to your neighbours.
            Juan Manuel Fahey

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            • #7
              Well, Harmon told me it is "likely" inverting. I would also think that they very likely boost a guitar signal before /processing sampling. I already have a voltage divider after a P-P, low Z 12au7 buffer and it's only 100K - even so it still overdrives (except on < 2) causing high frequency clipping that I hear in these studio monitors and live. I've successfully swapped in ICs before hence the pinout question. Less gain would be great + the added transparency of pure tube/capacitor/vol/DAC circuit.
              I'm also inspired by Tom Scholz and those 14million debut records.

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