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2204 Preamp control

Discussion in 'The Workbench' started by CROWEMAG, Oct 31, 2020.

  1. CROWEMAG

    CROWEMAG Well-Known Member

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    I replaced V1 and V2 tube sockets last night as a realized all of my preamp sockets were super loose. I used some nice Belton sockets. I noticed a change in the overall harmonic content of the amp after doing so. Is my mind just playing tricks on me or can loose/bad sockets reduce the bite/sensitivity?

    I will be doing V3 tonight....had to stop and watch Monday Night Raw with my son.
     
  2. thetragichero

    thetragichero Well-Known Member

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    the brain makes us hear all sorts of stuff that's not there
    belton micalex are quality sockets though
     
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  3. neikeel

    neikeel Well-Known Member

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    You are probably just hearing things. If the sound was dropping in and out I might have said yes!
     
  4. CROWEMAG

    CROWEMAG Well-Known Member

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    Either way it sounds better and as expected. Hahahahaha.
     
  5. Linster

    Linster New Member

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    Get rid of the .68 cap, it is too brittle in my opinion. Try a 22+ there with the 10K.
     
  6. yafal

    yafal Member

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    I would check the pot. Do this: unplug the amp, wait for the capacitors to discharge, then take a little live copper wire and tie toghether the two leads of the pot that are not connected to ground. Yo now have bypassed the pot. Reconnect the amp, turn it on, and see if the tone changed for the better. If the answer is yes, replace the pot. If not, maybe is the effect of the bleeding cap attached to the volume pot in most amps: when set to 10 it's bypassed, and the tone becames duller.
     
  7. Derrick111

    Derrick111 Active Member

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    Maybe your amp has a mod (may not be obvious when looking inside). A standard 2204 should give you anywhere from clean to breathing fire in tone so long as it is not in need of servicing, new tubes, etc. I assume you are plugged strait in so no pedal etc. is influencing your sound? I always suspect a mod or servicing.
     
  8. khan

    khan Active Member

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    You sound like the perfect candidate for a Treble Boost pedal. This is what occurred with a lot of guitarists in the 60's and 70's. They would push the amp to do all of the gain and found it muddied up the tone. They threw on a Treble Boost and it clarified all of that mud. Just do some research on TB pedals. I prefer germanium ones. It won't be cheap but, not crazy expensive. With the germanium, you pretty much have to put the pedal at the front of your "gain chain" on your pedal board. Fluctuations in voltage can cause an absolutely great pedal to sound like crap. You can also have a similar effect by using your Fuzz pedal with the fuzz turned all the way down. It really depends on the pedal though. Lots to play around with before you give up on the amp. And I agree with the above. Get the amp checked out by a really good amp tech who is familiar with vintage tube amps. They'll go through it and make sure it's in top running condition.
     
  9. CROWEMAG

    CROWEMAG Well-Known Member

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    That is out of there now. I removed that and put it back to 10K.
     
  10. mixn4him

    mixn4him Active Member

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    IF the bright cap is still there on the gain pot, the amp will sound brighter at 4-7 on the gain knob vs 10. In true stock form JCM800's dont have tons of gain and yes an SD1 crushing the input is pure gold..
     
  11. daveaust

    daveaust New Member

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    I like the idea of going back to stock and pushing with a gain pedal like has been mentioned, a treble boost or a fuzz turned back. I have a beano boost that you can select treble to full, and another option is a boss FA1 clone with bass and treble controls. I may be wrong about the Boss pedal name. It's that vintage FET boost pedal. Whatever. Any kind of clean to slightly gritty boost works. My 2204 (late 70's) is stock and has fair amount of preamp gain. Not super saturated but just the amount you want from a nice 2204 Marshall controllable with the guitars pot. Sounds like you do have a great amp brother.
     
  12. DC135er

    DC135er Member

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    Even the humidity in the air will change the sound.
     
  13. myersbw

    myersbw Well-Known Member

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    Make this one change if it's not been done before...change that bright cap (mounted between the end & wiper of the Volume control) from 500pF to a 120pF silver mica cap. Leaving that stock can be too brittle at lower volume control settings. Clipping it (as some do) can really detract from higher frequency harmonic content at anything less than full volume. To me, 120pF cap there parks it in the sweet spot for that circuit.
     
  14. shredless

    shredless Well-Known Member

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    Oh my... reading your posts is like flashbacks over the last 8 years or so of my struggle with my 2203x.

    It is a huge curve, but...by the time we figure it out...we will have a shit ton of knowledge about modding, not only marshalls either.

    I open mine up at least once a month, make tweeks and swear l nailed it...only to be let down a few days later.

    I learn more each time, l learn what does what and why mods do what they do. Keep going, it takes time and your mind and ears will play tricks on you.

    Mine is closer to what l want than it ever has been. But its a long road while we are learning
     
  15. CROWEMAG

    CROWEMAG Well-Known Member

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    I have figured a few things out over the first part of this week. My high input was speckled with rust colored dots.....changed it and it’s where I want it to be overall now. I think this jack was the issue all along in regards to what I thought I was missing. She’s all good now.
     
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