Replace tubes marshall sv20h

Discussion in 'The Tone Zone' started by Blaoskaak, Sep 14, 2020.

  1. Blaoskaak

    Blaoskaak Active Member

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    Hi,

    I want to place kt88 tubes in my sv20h. Is this possible? I know that i don't have to bias the amp. But i don't know if it fits.

    The reason i want to do that, is because i miss warmth and find my tone very Sharp.

    I play through a new cab 2x12 with 1 celestion vintage v30 and celestion g12m-65 . Both are new speakers.

    Thanks
     
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  2. pedecamp

    pedecamp Well-Known Member

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    You've got an EQ, dial your presence down? Jump the channels and dial in a happy medium between them for warmth?
     
  3. Sustainium

    Sustainium Well-Known Member

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    :slash: Are speakers broken in yet?
     
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  4. Blaoskaak

    Blaoskaak Active Member

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    Yes i jumped the channels. Of helped a lot. But i've read that kt88 also give's a thicker sound. So i am cursious what it does.

    No, not yet. I only played like 5 hours with the cab. Does it make a big diffrence?
     
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  5. Sustainium

    Sustainium Well-Known Member

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  6. pedecamp

    pedecamp Well-Known Member

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    I'm pretty sure you can put any tube in it since its cathode bias, I have yet to open mine to take a look, a KT88 is a pretty tubby tube in size, I'd get the size measurement spec to make sure they will physically fit before purchasing.
     
    Last edited: Sep 14, 2020
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  7. WellBurnTheSky

    WellBurnTheSky Well-Known Member

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    Definitely wait for your speakers to be worn in, makes quite a big difference. 5 hours at at-home volume definitely isn't enough. And maybe that speaker setup simply isn't working for you.
    And also, turn down Presence, it does make the amp sharp to the point of being shrill (it never is above 2, 3 at most, on mine). Especially at low volume. Same for Treble, my settings are pretty different at home and at stage volume with a full band.
    As for KT88, the point with them is to get more headroom, hence less compression, maybe they'll have a tad more low end, but that's it.
     
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  8. Shane Stevenson

    Shane Stevenson Well-Known Member

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    You will find better results with a speaker (s) swap. Get rid of the V30 first.
     
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  9. ampeq

    ampeq Well-Known Member

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    Don’t do anything until the speakers are broken in, about 50 hr’s. After that, if you still don’t like it try unplugging the V30. ***MAKE SURE TO RESET SPEAKER INPUT***
     
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  10. Blaoskaak

    Blaoskaak Active Member

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    Ok thanks. What do you mean with reset speaker input?
     
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  11. ampeq

    ampeq Well-Known Member

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    The ohm setting on the back of the amp you plug the speakers into. You may be using a 16 ohm load right now, but each speaker may be 8 ohm. Read the back of the speaker's if you need to unplug the V30, whatever the CB say's (like 8 ohm) set the speaker load to it. This is important, you can damage a tube amp with the wrong setting. It all depends on what they are running in the cab for wiring, and what the speakers are in ohm's. If you do not understand please look it up or PM me and I'll call you. Don't want to see you in a jam.
     
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  12. Blaoskaak

    Blaoskaak Active Member

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    Oh yes. I onderstand. I have 2 16ohm speakers. So that makes it 8ohm. I replaced the speaker with a new 16ohm speaker.
     
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  13. ampeq

    ampeq Well-Known Member

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    That is correct, so if you unplug one of those speakers, like the V30, you now would set your amp to 16 ohm. The way they wired it made it an 8 ohm cab, but a single speaker will be 16 ohm. Sometimes in testing we forget these things and BOOM! Amp down, I just did a boo-boo like this a few months ago. I was told a cab I was using to do some testing was one setting and it was not. When I went to run it with another speaker I have I got a new smell in the room, and it wasn't Febreze! I don't understand why they can't fuse protect against this, it's something that has plagued tube amp forever.
     
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  14. Sustainium

    Sustainium Well-Known Member

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    I keep an ohm meter among my gear to double check when connecting cabs to expensive amplifiers.
     
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  15. Blaoskaak

    Blaoskaak Active Member

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    Ok. Thank you all again for your help! I really appreciate it!!
     
  16. ampeq

    ampeq Well-Known Member

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    Me too, I trust nothing anymore. It's easy to plug in a cable and test to what you need, which is always funny the first time you do it because it never reads what you think it should.
     
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