1995 100watt Slp Super Harsh

Discussion in 'Marshall Amps' started by DannyB, Jul 7, 2018.

  1. DannyB

    DannyB Active Member

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    Me and search are not getting along, so a little help please!

    This amp is incredibly harsh to point of being useless with volume at 3 or higher.

    Would someone point me to the thread or threads I need to review?

    Or maybe it’s as simple as lifting a leg of a cap.

    Any help greatly appreciated!
     
  2. anitoli

    anitoli Well-Known Member

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    Harsh as in brittle highs and crakling lows? Prolly needs power/preamp tube.
     
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  3. Yugedrums

    Yugedrums Well-Known Member

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    How are you using it, as in... which channel, high-treble, normal, jumpering both?
     
  4. DannyB

    DannyB Active Member

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    Both channels jumped. But its also harsh on individual channels.

    It has a new full set of JJ tubes. Not my choice at all.
     
  5. jlinde1973

    jlinde1973 Well-Known Member

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    JJs should take away from the harshness if anything. You should check your bias for starters. Overly hot bias can sound very harsh as well as overly cold. Hopefully the amp isnt all modded to hell.
     
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  6. DannyB

    DannyB Active Member

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    What is a good ballpark figure for bias?

    I run my HJS and TSL 100 around 75-77mils
     
  7. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    Yes I hear this all the time....

    The amp must be played on 7 or higher, to drive the output tubes into distortion.
    This will make the amp incredibly loud.
    But this is the only way to play a Plexi.

    If you play the amp on "3," you have missed the point of a Plexi entirely. Plexi is a VERY clean amp.
    Until it is pushed to maximum.
    This is why the amp sounds "harsh."

    A. Play amp fully cranked.
    B. Use bridge pickup, and move pickup close to strings.

    C. Reduce loudness with attenuator, less speakers, Fluxtone speaker, or several methods. (one method is change output to Triode 40 watts)

    D. Change preamp to 2203, and install PPIMV.

    E. use high gain selected preamp tubes (makes a big difference)

    But if you keep playing amp on "3,"
    you missed the boat dude.
    Marshall is a different animal, it's not like other amplifiers.
    Plexi is not made for that application.
    It will always sound harsh, until you CRANK it and play it as God Herself intended.

    If you do not want to re-learn....you bought the wrong amplifier.

    Face the facts
    Plexi was made for stadiums, not bedrooms.
    You are trying to make it do something that it was never intended to do.
     
    Last edited: Jul 8, 2018
  8. AlvisX

    AlvisX Well-Known Member

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    It's the Gotdamn brite cap and that .0022 coupler
    Cut the brite cap value in HALF (dont remove) and change the .0022uf to .022uf ....you'll have a rock n roll machine

    This is of course MY opinion (the sh*t works) , I have been drinking, as my yard was just broken into and tools stolen ,so Im in a belligerent-er mood than usual :lol:
     
    Last edited: Jul 10, 2018
  9. mikebinthesky

    mikebinthesky Member

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    Not much worse than a thief-sorry dude
     
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  10. DannyB

    DannyB Active Member

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    As I said, 3 and higher, as in 8 ran into RockCrusher attenuator. It’s harsh every where. I could have explained that better.
     
  11. neikeel

    neikeel Well-Known Member

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    What speakers and guitars?
     
  12. DannyB

    DannyB Active Member

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    Gibson Les Paul and 335. Using older, pre-China 4x12 w/Greenbacks
     
  13. mickeydg5

    mickeydg5 Well-Known Member VIP Member

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    Is a sound clip possible?

    How long have you had the amplifier?
     
  14. Yugedrums

    Yugedrums Well-Known Member

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    Not sure "harsh" is specific enough for an accurate diagnosis... many would say the high-treble channel alone is harsh, especially below 3 or 4. Once cranked up however, it's "the sound" since the bright caps get cut out the higher you go and the output tubes start to break up... tone nirvana. :hbang:

    The normal channel is usually the complete opposite of harsh, very dull and smooth. When using a jumper and blending the two channels to taste ("EQ'ing" them essentially), you can usually dial in an acceptable and non-harsh tone.

    The best Plexi sound (in my opinion), is high-treble channel alone, cranked past 4-6 (if you can stand to be in the same house with it). Jumpering the channels at those volumes gets a little muddy to me.

    I can't speak to the added effects of running it through an attenuator though, as I've never used one.

    But yes, more specific descriptions and/or sound clips would help tremendously.
     
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  15. Geeze

    Geeze Well-Known Member

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    75 mA for EL34's? What is the plate voltage?

    Russ
     
  16. EndGame00

    EndGame00 Well-Known Member

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    Are you talking about insanely bright and cutting? I know a lot of Plexi owners sniping off the bright cap altogether...
     
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  17. DannyB

    DannyB Active Member

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    Re-biasing helped! Not a cure-all, but helped!

    Next up, bright caps!

    I greatly appreciate all the responses!

    You folks are great!
     

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