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Bypassing Peavey Tubefex DSP / turning it analogue

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  • Bypassing Peavey Tubefex DSP / turning it analogue

    Hello all,
    this is a long shot but has anyone here tried to bypass the DSP on a Peavey Tubefex? Mine just got back from a 8 month trip to Peavey but they were not able to fix it. I didn't get a full report but judging by similar stories I have found on various websites, the issue was probably the DSP chip which is hard to find because production ended in 2002.
    Peavey was very nice and sent me the schematics so that I can maybe do something with it myself. At the moment I'm looking at just going straight from the tube pre to the outputs. That should be easy enough. But i would be really nice to have at least an EQ as well. So far I haven't been able to determine if the EQ is done by the DSP as well. I think so because the EQ is after the AD converter in the flow chart...
    Any thoughts and comments are welcome!

    Cheers,
    Andy

  • #2
    Post the schematic?
    Sad state of affairs with this DSP stuff.
    Worse comes to worse, if you are successful in 'bypassing' the DSP, you can put an EQ pedal in front of the input.

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    • #3
      If you have the schemo, this should be gravy. What I would do is bypass the DSP section and insert a buffered loop with adjustable send/return levels in its place. That way you can use it for whatever analog or digital effect you want.
      The farmer takes a wife, the barber takes a pole....

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      • #4
        Post the schemo if you would. I'd like to see what they have goin' on inside the box....
        The farmer takes a wife, the barber takes a pole....

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        • #5
          Originally posted by Gtr_tech View Post
          If you have the schemo, this should be gravy. What I would do is bypass the DSP section and insert a buffered loop with adjustable send/return levels in its place. That way you can use it for whatever analog or digital effect you want.
          Cool, thanks for the replies. I have the schematics. I'll upload them when I get home. The computer froze when I just tried to do it.

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          • #6
            Here we go http://www.filedropper.com/tubefex

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            • #7
              That's a guitar amp?
              Good luck with that.

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              • #8
                It is a digital FX system with a bit of preamp tucked inside. I am going to look at it a while, but this really is not something for a novice to try.
                Education is what you're left with after you have forgotten what you have learned.

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                • #9
                  OK, here it is, my answer:

                  NO.



                  From the input, a couple op amp stages and right into the ADC. On the othe end, from the DACs, a couple op amps and out the jacks. There is no preamp there to bypass the DSP of, the whole thing is DSP. I am going crosseyed trying to even find just where the tube interface lives. But those tone controls, well all the knobs, are encoders, not pots. They are talking in digital bits. The volume controls for the input and output stages are done with digital pots.

                  The signal lines on the tube board have names like TBIN, CRUNOUT, LEADOUT. If someone with better eyes can see where those lines come from or go to, I'd appreciate knowing.
                  Education is what you're left with after you have forgotten what you have learned.

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                  • #10
                    Originally posted by Enzo View Post
                    The signal lines on the tube board have names like TBIN, CRUNOUT, LEADOUT. If someone with better eyes can see where those lines come from or go to, I'd appreciate knowing.
                    Probably not better eyes, but with PDF set to 400% ...
                    The page before the tube schem. has the relays, on relay T1401 & T1403 (area B6, I sunk your battleship) I see CLENOUT, CRUNOUT, LEADOUT.
                    Not sure if those are the points you are looking for or if those lines go to several places.
                    Originally posted by Enzo
                    I have a sign in my shop that says, "Never think up reasons not to check something."


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                    • #11
                      Can you attempt to find out 'exactly' what the problem is.
                      Peavey should be able to tell you.
                      I find it strange that Peavey 'bailed' on the repair.
                      They are usually on top of there own equipment.
                      There is a company in Florida that shows stock on the DSP56002 ic.
                      Link: Parts Matching DSP56002PV66 - America II Electronics
                      IF that is the problem.

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                      • #12
                        Click image for larger version

Name:	DSP56002FC66_7505.jpg
Views:	1
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ID:	828521Good gravy Batman!! You`re going to need awesome solder skills!

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                        • #13
                          I don't think that this is so difficult that you'd need Batman. Any company that assemble SMT boards can do it - you don't have to do it personally. As Jazz P Bass says, I would at least try to find out what is the problem. If you have schematic, this is not that difficult - I don't know why Peavey couldn't do it.

                          Mark

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                          • #14
                            All it takes is one proprietary chip in the thing becoming unavailable and the repair won't happen. If it were a TL604, they could dummy one up - like they have done already - but you can't knock out a new mask ROM from parts. PV is first rate supporting old models, better than anyone else I can think of, but this unit is 18 years old after all. Things that were state of the art then are passe now, and may not be available, especially if they are esoteric parts.

                            If you have schematic, this is not that difficult - I don't know why Peavey couldn't do it.
                            Markus, did you look at that schematic set closely? I sure as hell don't see it as simple.
                            Education is what you're left with after you have forgotten what you have learned.

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                            • #15
                              Number 1, there is not a Truth Table or description of all of the pin assignments.
                              A flow chart might help.

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