Small tube amps and their tubes

Discussion in 'Amp Owners Clubs' started by Dwightcarr11, Sep 16, 2021.

  1. Dwightcarr11

    Dwightcarr11 Strat-Talk Member

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    I currently run a bassbreaker 007 and an ac-4c1-12 in an a/b/y setup. I've got jj tubes in my vox, I've cut out the bright cap on the master and I've got a ceramic weber blue dog being built now for it.
    I love my bassbreaker much more though. However I need recommendations on tubes that might give me the most clean headroom. I would love to make it brighter. Not like my vox just more clear sound for longer. Any ideas? (Its still completely stock)
     
  2. dirocyn

    dirocyn Most Honored Senior Member

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    For less breakup, you could swap a 12ay7 for the stock 12ax7. That will result in a smaller signal and less distortion as you turn up. And it's easily reversible if you don't like it.

    Making it brighter--have you tried maxing out the Treble and cutting the bass on the TMB controls? If that is insufficient, you might consider swapping one of the connecting caps for a smaller one.
     
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  3. archetype

    archetype Senior Stratmaster Silver Member

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    I like the suggestions from @dirocyn. A 12AY7 in V1 position should push the point of breakup farther up on the volume knob.

    It's worth experimenting by changing one or both coupling capacitors to smaller values. Changing to smaller values doesn't increase treble, it decreases bass by raising the floor of the low frequency that's passed through. That may or may not change the perceived headroom.

    You haven't said if you have a combo or a head. In either case, a high efficiency speaker with a large voice coil and big magnet will typically stay cleaner farther up the volume knob. That doesn't affect amp headroom at all, but affects speaker breakup when cranked. Space is at a premium in both the combo and the Fender cab for the head, so measure carefully to see what speakers might fit.

    Good luck finding a schematic. Fender guards the Bassbreaker schematics like state secrets.
     
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  4. dirocyn

    dirocyn Most Honored Senior Member

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    Here's one.

    [​IMG]

    Take a look at the value of C18 compared to the other connecting caps, that seems the most fruitful change if you're looking to tighten up the bass response.

    I recently went the other direction on a Fender Excelsior that had insufficient bass (to my ear). It had restrictive 10nF (.01uF) connecting caps after the phase inverter, I went all the way up to .1uF (really a bass amp value) and it solved the issue for me.
     
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  5. Dwightcarr11

    Dwightcarr11 Strat-Talk Member

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    Any suggestions on what brand of 12ay7?
     
  6. Dwightcarr11

    Dwightcarr11 Strat-Talk Member

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    My apologies, it's a combo. Running them both stereo gives me a fairly "middle ground". But I don't always like to have them both on because i have to keep the volume down on each of them to the point of affecting my tone
     
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  7. archetype

    archetype Senior Stratmaster Silver Member

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    Cool. Good that someone traced it out and drew one.
     
  8. archetype

    archetype Senior Stratmaster Silver Member

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    I prefer NOS or used US, UK, or older EU tubes. GE, TungSol (not new TungSol), Sylvania or Philips, RCA, Raytheon. I wouldn't hesitate to buy a used tube that tests well. If you have to buy a new tube for some reason, my experience is that the JJ 12AY7 sounds "darker" than the normal tube would.

    https://www.kcanostubes.com/catalog/5r4gb
     
  9. Dwightcarr11

    Dwightcarr11 Strat-Talk Member

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    I bought a jj ay7 and also a sylvania. Plus a couple of nos el84s. Gonna do some experimenting next week!

    P.s. bought a 10 band eq and it's really helped a lot already
     
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  10. archetype

    archetype Senior Stratmaster Silver Member

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    Cool. Please report on the result. :D
     
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  11. Dwightcarr11

    Dwightcarr11 Strat-Talk Member

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    So I swapped the stock vox speaker for a 12" ceramic weber blue dog and the jj 12ax7 for a jj 12ay7. The jj el84 for an NOS Sylvania 84 and it sounds magical. Lost a lot of gain but its more than fine!
     
  12. mad axe man

    mad axe man Senior Stratmaster

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    definitely worth checking out a 7025 in place of a 12ax7 in V1...no gain loss but a lot smoother sounding tube...all my amps have em...ill never go back
     
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  13. Dwightcarr11

    Dwightcarr11 Strat-Talk Member

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    I'll see what I can round up. Just stuck the jj 12ax7 in my bassbreaker 007. So always can change it