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Discussion in 'Electronic Repair Modifications DIY' started by Link555, Oct 29, 2010.

  1. Link555

    Link555 Well-Known Member

    This is a link to my blog, in case any body wants to try this simple circuit ...out let me know....I would love some feedback....no pun intended;)

  2. Link555

    Link555 Well-Known Member

    OK so the build is done and testing is on-going. So far I want to make few minor changes. The impedance pot as suggest by Jensen is a nice tone shaper! But a pot may not as repeatable as switched resistors. The OPAMP drivers sound very clean, but I want to add an attenuator before them. I am wondering at this point if the gain pot is needed? Do I really want to overdrive the input of the amps? So far so good.
  3. Boswell

    Boswell Moderator Distinguished Member

    Neat project, Link.

    What are you driving the op-amp outputs of the device into - are they feeding the guitar amps? The gain controls you have on the op-amps can be set to unity, so there is little point in stripping them out. I can understand that the raw output of the interface is too much for the inputs of the guitar amps. You might be better off wiring in a fixed pad of 20dB or more in the amp channels and then using the gain adjust if needed. Most re-amp boxes I have used offer attenuations going up to at least 40dB.
  4. Link555

    Link555 Well-Known Member

    Thanks Boswell!

    Here is where this started from

    Yes a Pad would be a good idea. Rev 1 here we come ;) Last night I changed where I tapped the op-amps from pin one of the pot to the wiper, and that gives a bit of a divider to the input of the opa2134's. Which helps.... I am running these op-amps straight into different guitar amps.

    I saw another circuit where they used a inductor to feed the guitar amplifier, to simulate a guitar output. Personally I like the tone not dragged down, Maybe for a distortion sound this would sound smoother.

    I am happy with this prototype now, but if I get back to it I will lower available gain to the op-amps, add a few switchable pads and simplify the ground lift switches.

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