DSL 50 C12 mod advice please

Discussion in 'The Workbench' started by Mike_j, Oct 20, 2009.

  1. Mike_j

    Mike_j Active Member

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    Hi,
    I been reading a fair bit about the C12 mod on DSL 50 heads and have 2 questions:
    1. Does it add more "body" to the red channel bringing it a bit closer to the fullness of the green channel, and take out some of the thin high end fizz?

    2. Realistically, how hard is it for a complete beginner to do? Is it just a case of unsoldering the capaciter?

    Any help/comments appreciated. Thanks.
     
  2. Wilder Amplification

    Wilder Amplification New Member

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    Unless you have a solid grasp on basic electronics, I advise against attempting anything inside of a valve amp simply due to the high voltages that exist inside of them (up around 400-500 volts...much higher than what comes out of your wall). I suggest you take it to a reputable tech who's familiar with valve amps.

    As far as the mod, I have no idea since I've never played much through a DSL amp other than to test one out after fixing it.
     
  3. Mike_j

    Mike_j Active Member

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    Awesome. Thanks for that.
     
  4. jcmjmp

    jcmjmp Well-Known Member

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    C12 is a relative to a specific given set of board revision/issue numbers. It should be pretty simple to do but unless you know what the cap is supposed to do, it will be hard to determine if you're removing the correct component.

    what is it that you're trying to fix? You want more bass on the Red Channel? Beware - too much bass on a high gain channel can lead to flubbyness.
     
  5. Mike_j

    Mike_j Active Member

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    jcmjmp

    I'm finding the red channel too "thin". I'd like to get it a bit more full sounding.
    I'm taking it to my tech guy tonite but I'd like to be able to offer up some suggestions to him.
     
  6. jcmjmp

    jcmjmp Well-Known Member

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    Maybe your tubes need changing?

    I can't describe the lead channel as "thin". Do you have an eq pedal or rack mount? If so, experiment with it in the loop and try to figure out which frequencies fill the sound up and take it from there.

    "Thin" sounding is highly subjective.
     
  7. Wilder Amplification

    Wilder Amplification New Member

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    Not knowing much about the DSLs having never owned one, according to the schematic for the DSL50, from what I can see C12 is a 470pF cap in the reverb recovery stage. If that's the case, I doubt a mod having anything to do with that cap will help you.
     
  8. jcmjmp

    jcmjmp Well-Known Member

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    Wilder: As I've already stated in an earlier post, C12's location and function is different depending on the board you're looking at and the issue/rev you have...

    He's probably referring to the treble bleed cap on VR3, on the control board.
     
  9. Wilder Amplification

    Wilder Amplification New Member

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    Based on this, am I to assume the component IDs on the master schematics mean nothing due to the few board revisions they've had on these amps over the years?

    Or do they come up with updated schematics with revised component IDs everytime they revise a board?
     
  10. jcmjmp

    jcmjmp Well-Known Member

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    1) There's the HW board rev - JCM2-60-00 where the "00" is the rev number. This is a different physical board and layout, which also means different component IDs.
    2) There's the Issue number. This is a "soft" change where certain component values might change, but its essentially the same board.

    Schematics for the DSL specify which HW board and issue number they are for.

    I'm actually working on a DSL info page that will contain some of this info, along with upgrade components and tips/tricks.

    www.lydian.ca

    If just have to get over my chronic insomnia and get some energy back before I can start putting some real time on the page. I also want to get my PT/OT protos tested.
     
  11. Mike_j

    Mike_j Active Member

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    Thin, fizzy, no body of fullness to the tone. I want the red channel a little closer to the tone of the green but still retain some overdrive. Sorry, I can't be any clearer.
     
  12. jcmjmp

    jcmjmp Well-Known Member

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    A bad tube could cause that, which is why I suggested a tube swap.

    Looking for more bass? Low Mids? High Mids? Does it sound like you want with the deep switch in?
     
  13. Mike_j

    Mike_j Active Member

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    No. The red channel still sounds pretty gutless. Yes, the tubes probably do need changing and I'll get tech guy to do that. I'm not sure that would explain the tone disparity between the 2 channels. Either my amp is fucked or it is the way the amp is designed.
     
  14. Buggs.Crosby

    Buggs.Crosby New Member

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  15. Mike_j

    Mike_j Active Member

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    Got it sorted. Thanks all for the help.
    Took it to my tech guy who suggested changing the capacitors (that he felt were low quality), test it out in a band and recording situation BEFORE deciding to start pulling things out.
    I felt it was good advice so I'll go with that. He also thought the power transformer was pretty shitty too and that could be in for a change a bit further down the track.
     
  16. jcmjmp

    jcmjmp Well-Known Member

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    Good Idea.
     
  17. MaidenStrat02

    MaidenStrat02 New Member

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    The C12 mod is pretty much automatic these days. Some people swap out different values, I clipped it. Cuts down on that harsh treble in the Ultra channel
     
  18. Ken

    Ken Well-Known Member

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    Hmm...on my DSL 50 the ultra channel is noticable brighter than the green channel like everyone talks about but it's not "harsh" at all. With the added distortion I like that brightness; to my ears it enhances the tone just right. I wouldn't change it.

    Frankly I don't see the point on having both channels sound the same except for overdrive; I've read complaints about the shared EQ meaning you can't make them similar and I have no problem with it. It IS a TWO channel amp after all, not a one channel with a massive gain knob. Both channels SHOULD sound different!

    Ken
     
  19. AdamR

    AdamR Active Member

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    This is the same issue Im having with my DSL50. The red channel just sounds think to me know matter how I EQ it.
     
  20. solarburnDSL50

    solarburnDSL50 Well-Known Member

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    Try this. Put the red channel on lead 2(button in):

    Presence-0 to 2 or 3
    treble-4
    mids-7
    bass-4 or 5 bass boost in
    Gain-3 or 4
    volume-3
    Toneshift button out

    Clean boost lead 1 to warm it up. Tubes that are warm and dynamic help. Speakers and cab can warm it up. EQ in the loop may help. Guitar and pick ups can warm it up. Acoustic foam placed a certain way on the speaker cab can control ice pick frequencies.

    I'd mod it last but that's me.
     

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