Monday, 21 September 2020

Framus Cobra Pre Amp Lead Channel

 

 

 

10 comments:

  1. hello Fuzzhead,
    Do you have a schematic for this?
    Thanks.

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    1. No, I don't have the schematic on hand but will get back to you when I do!

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  2. hi fuzzhead, did you happen to find the schematic? I would like to give it a go. Thanks.

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    1. Sorry, totally swamped in DIY stuff and work at the moment. I have not forgotten your schematic request. When I get home from work in a week or so, I will search through my hard drives for the schematic...

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    2. Hey crissp!
      Got home earlier than expected and managed to locate the schematic.
      Looking at it again, some things could probably be improved:

      The tone stack looks VERY lossy so a recovery stage might be necessary.

      And I think it might be worth with experimenting with small value miller caps across the Gate and Source for ome of the FETs?

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  3. Thanks fuzzhead. I will have a look at it.

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  4. it looks very similar to the bogner ecstasy, less the tone stack and of course some values. I might give it a try.

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  5. Layout is verified. Good sounding preamp, biased the drains of the fets at 1/2Va, with the exception of Q5 which needs over 6V to reduce noise/hissing. I have not tried it yet with a booster or mild od in front, but my feeling is that it may sound better. Will experiment more after boxing. Low frequencies are cool. Thanks fuzzhead. Cheers!

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    1. Excellent! It is now tagged. Let us know how it works at higher volume with a booster upfront.

      I'll correct some faulty values in the schematic when there is time for it.

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