Marshall Tsl 100 Head Crackle

Discussion in 'The Workbench' started by thunderstruck507, May 3, 2017.

  1. thunderstruck507

    thunderstruck507 Well-Known Member

    Joined:
    Apr 20, 2017
    Messages:
    314
    Likes Received:
    353
    Hey guys, I recently acquired a used TSL 100 head and so far I've been really enjoying it.

    Now that the new is wearing off and I'm working on dialing in tones I have found that on the clean channel when playing I sometimes get a very light crackle. It seems to be more present when playing a high output pickup and also an overdrive set to clean boost.

    I have ruled out the pedals, the instrument cables, and the speaker cable.

    The same crackle can be heard when turning the gain knob for the clean channel.

    If the crackle is present on the Crunch or Lead channels then it's hidden under the distortion but I really tried to hear it and cannot.

    I've tried replacing the V1 and V2 tubes with spares as well. The amp has Mullard power valves replaced by the previous owner. I checked the bias which was set hot with 85 mV on one bank and 90 mV on the other bank. I rebiased that side to 85 mV as well which is still hot but not at the limit which I understand to be 90 mV.

    I did some research and a common answer seems to be replacing the main board. That's obviously drastic so I though it couldn't hurt to ask for other ideas before it comes to that as they are $225.


    Other than that small issue the amp seems to be working well. I've never owned or heard one so I can't be certain. I do need to use the deep switch and run the bass knobs around 6-7 to get much low end but it sounds good that way. This gives it more low than my DSL401 had but I would say not quite as much as my roommates 60watt Peavey 6505+ into the same 4x12 configuration I run (vintage 30s and g12t-75 in an X pattern in high quality birch angled cabs).

    Thanks in advance for any tips I might be able to use. I'm also open for any other suggestions regarding the amp or settings from those who are more familiar with the amp.
     
  2. RickyLee

    RickyLee Well-Known Member VIP Member

    Joined:
    May 22, 2010
    Messages:
    9,726
    Likes Received:
    3,219
    Location:
    Riverside CA U.S.A.
    Can you list all your control/EQ settings including any of the switches that are engaged on the front panel? Also, using anything in the loop? FX loop settings including the dB setting on the back would help as well.

    What year is this TSL100?
     
  3. ampmadscientist

    ampmadscientist Well-Known Member

    Joined:
    Jun 26, 2014
    Messages:
    15,607
    Likes Received:
    9,529
    Location:
    Start the reactor... Free Mars!

    Plug a guitar cable between effects send and effects return, then re-test, make sure it's not a bad switch contact in the jack, first.

    You can either change the board or install the Dr. Tube bias stability mod.
     
  4. thunderstruck507

    thunderstruck507 Well-Known Member

    Joined:
    Apr 20, 2017
    Messages:
    314
    Likes Received:
    353
    I am not sure what year as I haven't looked around for it yet. Will do though.

    On the clean I was running it with EQ: Bass 4, Mid 5, Treb 6, Vol 3 to 4, Gain 7, no mid boost, Presence 4, Reverb 5, FX 5. VPR was off. I originally had more Bass dialed in but it was just too much and choked the tone...reducing the lows made the clean sound more open and Fender like. Even at 4 there is a lot more low end on the clean channel than on the Crunch or Lead channels.

    On the Crunch I have the EQs near straight up at 5 but a little more bass and little less treble, deep switch is engaged and tone shift is not. Gain moves from 3-5 depending what I'm playing and volume is around 2. Presence is around 3.5, reverb around 2. MXR overdrive in front with level max and gain zeroed, tone straight up. These settings give some excellent classic rock sounds and sounds like what I picture in my head as a typical Marshall tone. It really opens up and starts sounding even better as the volume gets closer to 3.

    On Lead I have the EQ: Bass 7, Mid 3.5-4, Treble 5-6 (depending on guitar), deep engaged, tone shift not, Gain at 5, and volume at 2. MXR overdrive in front with level max and gain zeroed, tone straight up. These settings give a great metal tone to my ears as long as the volume doesn't drop below 2, then it becomes brittle and compressed sounding.

    There is a MXR analog delay and a Behringer chorus in the loop. The crackle was present with or without the FX loop engaged by the footswitch. I am unsure what the db setting on the loop is.

    In addition to the light crackle sound (which was also sometimes present on the clean channel even when not playing anything and the Boss NS-2 set to mute) sometimes there is a fairly loud pop when switching on from standby.


    Last night I played some more for a while and didn't notice the crackle (but I was mostly playing on the Lead channel). After an hour of playing I let the amp set on the clean channel with the vol and gain maxed and checked bias again after a few minutes. The left bank of tubes was back up to 92mV and the right was sitting at 83mV. I tried for about an hour to balance them and couldn't get them to balance. When I turned the amp off they had settled on 82mV left and 75mV right. I'm wondering if the tubes are not a matched set? My next plan was to try moving the power tubes from bank to bank and see if the bias followed them.

    This is my first 100watt head so the hum I hear when the amp is on but nothing is being played could be normal. I do know the crackle is not normal. My DSL401 had the same crackle at one point but it went away once I replaced all 4 preamp tubes.

    NOTE: I am mechanically and electrically inclined with cars and guitars, but have only recently within the past year begun tinkering with tube amps. I do realize things such as the voltage dangers even unplugged if the amp is not discharged and things of that nature but I am by no means overly fluent in amp repair or diagnostics I am trying to learn.
     
    Last edited: May 4, 2017
  5. Gunner64

    Gunner64 Well-Known Member Premium Member

    Joined:
    Nov 16, 2013
    Messages:
    5,557
    Likes Received:
    6,741
    Location:
    Midwest, USA
    The crackle may be Tube sockets that need a cleaning. Give the 12ax7s a nudge one by one and the culprit will usually show its self..may not be the issue but its possible and I have had that issue more than once.
     
    Last edited: May 4, 2017
  6. thunderstruck507

    thunderstruck507 Well-Known Member

    Joined:
    Apr 20, 2017
    Messages:
    314
    Likes Received:
    353
    Just a small bit of follow up, it seems the crackle is related to either the volume pot, gain pot, or the mid boost switch on the clean. I haven't taken it apart to look but it comes and goes and sometimes gets worse when messing with those things.

    What little time I've had to mess with the amp I spent playing it rather than taking it apart being a new to me toy and all...previous suggestions were def appreciated and I will still give each further consideration.

    The amp sounds insanely good once dialed in. The biggest tricks seem to be running enough volume and being conservative with the gain. Both of these open up the sound a good bit and as long as the volume is at no less than 2 on the drive channels it roars pretty good. Seems to really come alive once turned up to closer to 3 and higher.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice