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Help! Anyone else have trouble dialing in the YJM100? Muddy mess?

Discussion in 'Marshall Amps' started by Crazytrain513, Sep 14, 2021.

  1. Crazytrain513

    Crazytrain513 Member

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    Hello there! I apologize in advance for the length of this post but appreciate any guidance from the experts out there.

    I recently picked one of these up and have been messing around with it. I had one a few years ago and foolishly sold it so it’s nice to have one back in the family after a long search! These are getting tougher to find and the pricing is getting pretty crazy too (for good reason I imagine).

    As I remember, cranking up most of the knobs to the right gets me a nice Plexi sound that sounds good for Led Zeppelin, early Def Leppard, Van Halen, etc. I can then throw on a Tubescreamer or Distortion+ and get some good Scorpions, Ozzy and Iron Maiden tones too.

    But sometimes I am too lazy to drag my pedalboard around or just feel like plugging straight-in. I will then gravitate towards using the onboard DOD and a couple things happen.

    First, a TON of highs enter the mix. i find myself having to adjust my pre-boosted treble and presence from an 8 or 9/10 on the dial without the boost to a 3 or 4/10. This is well-documented by many users and is what it is and is a non-issue.

    Second, the volume jumps up quite a bit. Also normal I believe. The way I found best to use the boost was to just have the “gain” knob all the way up and dial up the “level” knob to taste to get the amount of overdrive I need (I find I don’t need to go past 11 or 12 o’clock typically).

    That’s all fine but the real issue is this: the amp gets SO MUDDY on the lower strings. Playing power chords is absolute unusable mush as if a fuzz pedal is on full blast. No matter what I do I can’t seem to dial this out. The only way I can seem to affect it is by LOWERING the midrange (you heard right) which I typically have around 8-10 (which then drowns my tone out) or by adding more gain on the boost to cut through it which then just ends up being way too much gain and a trebly mess.

    Has anyone else experienced this? My last YJM had this same characteristic and I am using the same speakers as well - a Marshall 1936 cab loaded with Vintage 30s.

    Any thoughts appreciated. Thanks!
     
    Last edited: Sep 18, 2021
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  2. Chris-in-LA

    Chris-in-LA Well-Known Member

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    You didn’t mention your bass control or if you jump the two channels.
     
    Last edited: Sep 14, 2021
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  3. purpleplexi

    purpleplexi Well-Known Member

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    I've been experimenting with dropping the mids lately which seems counterintuitive but my theory ( which may be rubbish) is that the modern amps have far more mids available than the old amps. Combine that with a bit of bass and you're making mud.
    It's quite a trick balancing everthing up without too much bottom and without it sounding too spikey. Of course upping volume tends too smooth things out at the top but there are limited occasions when you can do that with a 100 watter.
     
  4. Buzzard

    Buzzard Well-Known Member

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    I woul'd use the upper left input if you aren't already.
     
  5. pedecamp

    pedecamp Well-Known Member

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    Have you tried jumpering the channels? Maybe its time to change the tubes?
     
  6. Crazytrain513

    Crazytrain513 Member

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    Sorry about that - the bass is usually pretty high (6-8) depending on the sound I am going for with the boost off. However, when I engage the boost, no matter where the bass is, the fuzziness does not dial out. The tone just thins out as I bring the bass down.

    Worth mentioning I always am plugged into the top-left input.

    I will, on occasion, jump the channels and then this helps with smoothing out the fuzziness on the lower bass strings drastically with both volumes cranked but this obviously leads to too wooly of a sound and as I lower that second volume, the fuzziness returns the lower that second volume knob goes.

    I did auto-bias the amp a few times and it does now show any tube failures and it looks like all the tubes are glowing in the back. Do you think the tubes are just too weak after years of use? I did, after-all, buy a 10 year old amp secondhand.

    As I mentioned, I seem to remember my old YJM also having this sound “characteristic” too though. Although that was also a secondhand amp and thereotically could very well have needed tubes as well.


    Thanks again for your responses so far!
     
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  7. scozz

    scozz Well-Known Member Gold Supporting Member

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    Sorry, I’m not quite sure what you mean, if your last YJM had the “same characteristics” why are you surprised this one does too?
     
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  8. pedecamp

    pedecamp Well-Known Member

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    Might be worth putting some brighter tubes in, anything Chinese if you can find it, or Tungsols. The amp probably came with the same old dull JJs they always come with, or the seller put his worst tubes in it to sell.
     
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  9. Crazytrain513

    Crazytrain513 Member

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    Not so much “surprised” as wondering if this is how they all are or if the two secondhand ones I have had are both like this and that this is something that can be “fixed” (i.e. bad tube, biasing issue, etc.)

    I don’t know too much about amp maintenance so I apologize for any silly upcoming questions as I usually have not held onto an amp long enough for it to be needed. I all-in-all see this amp as a theoretically perfect amp for me though so am definitely interested in making it work as a keeper. My guitar tech always says I know exactly what I want to hear and know when something I needs to be different but just need the expert hand to help me get there.

    1) If I pop open the back will the tubes have branding on them? Are JJs not good tubes? Assuming different tube manufacturers affect tone like anything else, what tubes would help me get the hot rodded Plexi tone of the artists I had mentioned in my original post that I seek to sound like? Obviously I thought a Plexi-style amp was the obvious choice and the fact that this amp has the EPA also made sense to me so I could get close to those tones at a more reasonable volume.

    2) My guitars and the amp itself already seem pretty bright as I find myself constantly lowering the treble/presence or the tone knob on my guitar when dialing in tones.
    Would brighter tubes still be the issue? It almost seems like something is wrong with the amp rather than something with the eq controls but correct me if my original post makes it seem like that is not the case.

    Thanks again
     
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  10. pedecamp

    pedecamp Well-Known Member

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    Your original post said your tone is muddy.

    I dont like JJ, alot of people dont like JJ, but then alot of people do like JJ. They are dark and dull to my ears, but you need to decide. Tubes will have print on them saying what they are.
     
  11. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Start with lower gain settings. Too much gain becomes mud. And you will often find that you don't need as much gain as you might have guessed.
     
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  12. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    Shot power tubes will sound brittle on low notes, or more specifically the breakup isn't pleasing to the ear. Since that amp has an auto bias setting up a new tube set is easy. Try new power tubes.
     
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  13. Crazytrain513

    Crazytrain513 Member

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    The tone IS muddy in the low end, it is also quite bright in the high end. Hope that makes some sense. The highs can be piercing with the treble too high but the lower strings are just mushy and fuzzy in a non-pleasing way.

    it’s also strange how it seems that this problem is eradicated to some degree by jumping the channels despite this boosting the low end. That’s why I don’t think it’s as much of a dialing-in problem as it is with something internally.

    agreed, and thank you for your input. I will say the gain is pretty low though. Scorpions or Van Halen II is about as gainy as I go.

    this may be the solution. What type of tubes would be the most desirable based on the tones of that artists that I am seeking ?
     
  14. marshallmellowed

    marshallmellowed Well-Known Member

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    OK, you've had 2 YJM's, and you're saying they both had "this same characteristic". Based on that alone, I'd say there's nothing wrong with the amp. Either that, or both amps had the same problem, which, while not impossible, is very unlikely. Beyond that, can't tell you, unless it's a muddy sounding guitar, which some guitars are.
     
  15. pedecamp

    pedecamp Well-Known Member

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    What volume are you playing at? Maybe a big amp at bedroom volume isnt working. How does it sound at band volume? What speakers and cab are you using? Are the speakers broken in? What guitar and pickups are you using?
     
  16. Justin Whitstine

    Justin Whitstine Member

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    I can think of several solutions, but they all involve adding pedals.
     
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  17. marshallmellowed

    marshallmellowed Well-Known Member

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    Thought of something else. You mentioned the amp only exhibits this characteristic with the on-board boost engaged (I think that's what you're saying). If that's the case, you may have a damaged amp. There's a history of issues with the on-board boost in the YJM, one that prompted Marshall to issue a repair bulletin. I don't remember the specifics of the symptoms of this issue, but I do know it was related to the on-board boost. The problem was common enough that, unless you bought the amps new, you could have gotten 2 used amps which had that issue.
     
    Last edited: Sep 17, 2021
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  18. FIFTHANGEL

    FIFTHANGEL New Member

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    Yngwie is very particular, he runs his amps with high gain and low output pickups. Get a strat, and yjm fury pups. It's the pickups you're using that are the issue. The yjm are unforgiving as hell low compression pups. They do slightly distort but stay open with a lot of headroom. It's yngwies ears....
     
  19. bigbadorange

    bigbadorange Well-Known Member

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    [​IMG] As someone that owns and loves my YJM. Make sure the onboard OD is working, there is a TSB on them breaking. 2nd on the pickups, probably a high out put or active pickup is not your friend with this amp, and third....although possibly obvious, what are the gain settings (on back of amp) for the onboard OD? It has its own volume and gain settings.
     
  20. Kinkless Tetrode

    Kinkless Tetrode Well-Known Member

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    What guitar are you playing? 25 1/2" scale and an all maple neck might go some way to helping this.
     

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