new Marshall DSL 40 and 100 cap "mod"

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers T' started by tmac, Dec 8, 2012.

  1. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    not sure if this has been covered yet, so...

    the old Marshall DSL heads C12 cap mod (disconnecting the 470pf that is across the OD channel gain pot) is cap C19 in the new DSL 40 combo/100 head. sits right behind the pot on the board. I just left in place but lifted one leg of connection so that it is out of circuit. easy to put back if needed

    really makes a big difference in brightness (harshness to me) of the OD (red) channel if like me u run gain pretty low (and crank the volume) for a more vintage type OD tone. and really matches up the tones of red and green (clean) channels in my opinion.

    this really depends on your playing style, guitar, speakers, etc. some find this channel too bright but some may like the cut it provides with the cap in place. and if you are cranking up the gain pot it is probably not an issue (because the more the gain pot is turned up the more this capacitor is out of the circuit). this mod also cuts out some hiss noise. a lot of folks hate these DSLs, lot of folks love 'em, but it sounds great to me - with this mod.

    I can post pics if anyone needs.
     
  2. Prattacaster

    Prattacaster Member

    Joined:
    Jul 12, 2010
    Messages:
    1,375
    Location:
    Nashville, TN
    Those amp really shine on recordings and live. They seem mediocre when used for practicing and jamming; stick a mic in front of them and they are glorious.
     
  3. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    I agree somewhat, these DSL's (& pretty much like any good Marshall) sound best cranked to get those EL-34s workin'. that smooths out the fizz of the cascaded preamp gain, plus you can actually decrease the preamp gain too. this is the way they're meant to be used I think and in live settings they blend beautifully. I prefer my original builds/mods with the vinatge non-cascaded 1987/1959 circuits but they have to be cranked (like we used to in the old daze lol) to get that grind. if I use those I have to bring along a tube screamer for grind at "reasonable" volumes and still usually have to use one of my Prineton Reverbs instead. with the DSL you do have some volume control and still get pretty good Marshall flavor at what is now considered reasonable gig volumes. I like the old days when we didnt mic everything and we cranked it.

     
  4. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    let me add that the digital reverb in these new DSLs is ok but not as good as I remember the older ones with spring rev. this amp seems to be pretty well built and has beefy iron. punchy 40W too. conservative rating imho. I have not changed tubes or anything, all stock glass, didn't check bias. looks like two trim pots inside chassis for bias adjust.
     
  5. Kenster

    Kenster Member

    Joined:
    May 26, 2002
    Messages:
    218
    Location:
    Spokane Washington
    Did you have to remove the board to lift the leg of the cap? I picked up a 40C and it sounds really good to me. But like you I preferred to keep the gain low on the Lead channel which makes it quite bright. I usually used lead 2 since it has a bit more bass even with a low setting which helped quite a bit.

    Also I put in a G12-65 which also tamed the overall brightness of the amp compared to the 70/80 it came with.

    Pics would be cool if you have them handy.

    Thanks for posting this mod.
    K
     
  6. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    u r welcome. ok, I'll post some pics I took when I opened her up.

    You don't need to lift the board or anything, just make sure caps are discharged and unsolder one leg and lift the cap so that leg pulls out. I did the right cap leg (with rear of chassis facing me) as it was easiest for me and was more room on that side.

    Before I bent the leg up and out of the way I plugged in my LP and played while I pressed down the leg (with my plastic non-conductive probe tool!) to make contact again to hear the difference with it in and out of the circuit. Quite a dramatic difference.

    I like the idea of a G12-65, might have to try one.

     
  7. Kenster

    Kenster Member

    Joined:
    May 26, 2002
    Messages:
    218
    Location:
    Spokane Washington
    Thanks Tmac for the pics in advance. One more question. What wattage soldering are you using on this board. I have the usual 40 or 50Watt for doing wiring to terminals and guitar circuits but that might be too hot. I also have 25 watter which might be the ticket.


    Cheers
    Ken
     
  8. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    pics are unmodded state

    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Dec 10, 2012
  9. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    I used my 40W but used a fairly sharp tip. I like to work hot but get on & off the part quickly and have many years doing so. I'd recommend the 25W, should be just fine because it's a tiny area. Good luck and let us know what you think.

     
  10. Kenster

    Kenster Member

    Joined:
    May 26, 2002
    Messages:
    218
    Location:
    Spokane Washington
    Excellent. 25 Watt it is. I'm pretty sure I'm going to like this mod. Now I just have to find the time to actually do it :). Im liking this amp more an more so this will just take it over the top. Only other thing I wished it had was footswitchable modes. I know.. can't have everything.

    One other thing I noticed was when checking the bias only the left trim pot as you face the back of the amp actually changed the bias. Tried the right one and it did nothing. I did notice an increase in hum when I moved it from its original position so I moved it back till it was quiet again. Maybe this is a balance control??

    Anyway this a very cool sounding amp, especially for its price point.
    Thanks again for the info. I'll let you know what I think of the mod when I get around to it.
    Ken
     
  11. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    thanks Ken, good info on the bias pot, I agree the other trim pot maybe a tube balance or hum balance on the heaters? Haven't seen a schem for these yet, so if anyone has a schematic please post. btw, what did you bias to? did you check plate voltage on the EL-34's?

    When anyone attempts this mod don't force anything and lift the cap lead out carefully, the board traces can be fragile & we don't want any torn or lifted traces. There does seem to be enough of a leg on the cap to cleanly clip & be able to solder back if needed but I don't like doing it that way.

     
  12. pdf64

    pdf64 Member

    Joined:
    Aug 9, 2008
    Messages:
    2,464
    Location:
    Staffordshire, UK.
    Were you monitoring the current on the right tube at the time (or did you leave the meter on the left one)?
    If hum increased when twiddling the right one, a likely cause of that is an imbalance in the OT primary currents of either leg, ie the trimmer really was changing the current.
    Just checking, human error is something we're all qualified for.
    Pete
     
  13. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    a little OT but I like your band Pete and the tones you're getting, sounded vintage Marshall-y, what amp you using in those clipz?

     
  14. Kenster

    Kenster Member

    Joined:
    May 26, 2002
    Messages:
    218
    Location:
    Spokane Washington
    Honestly Pete I don't remember since its been a couple months. If I recall I was using one of Eurotubes Bias Probes hooked to the right tube when facing from the back and nothing was changing as I was using the right pot. Just the increase in noise(hum) which was real faint. I then changed the Bias Probe to the left tube and was able to adjust the bias with the left trimmer. Using the right trimmer just increased noise again. Who knows I could have done something wrong initially.

    I would like to confirm for sure what the right trimpot does, so we'll have to wait for schemes to come available or someone who knows from their technical prowess.

    I ultimately set it to 70% dissipation which again if I recall was around 32 to 36 ma. It was a little colder than that from the factory but not too bad. Sounds bitchin now though :dude.

    Ken
     
  15. Jose Eduardo

    Jose Eduardo Member

    Joined:
    Jul 22, 2002
    Messages:
    211
    Location:
    Boston, MA
    Thanks for the tip. I just got a DSL40C. I like the sounds I'm getting so far. Do you know if there are sound clips available anywhere comparing the sounds?
     
  16. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    I'm not aware of any clips at this time, but if you like it now, seems to be no need to mess with it?

     
  17. Jose Eduardo

    Jose Eduardo Member

    Joined:
    Jul 22, 2002
    Messages:
    211
    Location:
    Boston, MA
    Absolutely, I don't see myself doing that. I was more curiosity than anything else...
     
  18. Kenster

    Kenster Member

    Joined:
    May 26, 2002
    Messages:
    218
    Location:
    Spokane Washington
    I finally got around to doing this mod. Took me all of 10 minutes to do. All I can say is what was Marshall thinking putting that cap in. Removing it made the transition from the Green Channel to the Red Channel very smooth. I had the Lead One Red Channel set for 3 - 5 on the gain knob and there was zero increase in treble frequencies when switching channels. Only change was a thicker sound at whatever volume you want. I don't miss the separate EQ at all now.

    I would encourage anyone to try this mod and like TMAC says it's reversable and be mindfull of the precautions when going inside of these amps. I really love the tones this amp can out but now it's a great versatile amp for the money.

    Naturally when it come to tone and features YMMV.

    Cheers
    Ken
     
  19. Rod

    Rod Tone is Paramount Gold Supporting Member

    Joined:
    Nov 29, 2004
    Messages:
    10,539
    Location:
    New England
    Great info! !!
     
  20. tmac

    tmac Goldmember

    Joined:
    Jun 29, 2002
    Messages:
    1,433
    Location:
    The Swamp
    my sentiments exactly Kenster. glad mod worked out. did you just lift out one leg or remove cap altogether?

     

Share This Page