Preamp vs powertubes question

Discussion in 'Amps and Cabs' started by cdntac, Feb 10, 2012.

  1. cdntac

    cdntac Member

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    Playing at low volumes, will changing the preamp tubes make more of a difference as opposed to changing powertubes?

    There's no hiss or crackling or microphonic issues, I'd just like to get a more smooth gain out of my Peavey Classic 50 (hence the reason for my question in another thread about combining a 6505+ head with it).

    At louder volumes the gain sounds quite nice but at lower, normal-sized rooms, would it make a difference putting new preamp tubes in.

    The current JJ 12AX7 preamp tubes have been in there for a good 2.5 years and have seen a fair amount of use (at max gain).

    If the power tubes were replaced, how much of a difference does the Groove Tube power ratings make on their EL84? ie: 4 vs 7? That's what I can get locally.
     
  2. solitaire

    solitaire Senior Member

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    The power tube ratings determine how soft the bottles are, hence how much they compress and when they distort. Could fiddle about with various ratings, but they still put out their rated power as max clean power. Probably you wouldn't notice much difference at such low levels.

    Crackling would indicate it's the preamps that's on the blink.
     
  3. vibrostrat43

    vibrostrat43 Supporting Member

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    To answer your question simply, the answer is yes...at low volumes preamp tubes will have much more impact on your sound than power tubes will.
     
  4. cdntac

    cdntac Member

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    Thx. I've been using a subtle bit of OD on my amp (in conjunction with the gain) and today tried it without the pedal.

    It sounded a bit thinner, more muddied than I remember so I thought perhaps new preamp tubes.

    Is it best to swap all three or just the one (V2) that is for distortion?
     
  5. Blue Strat

    Blue Strat Member

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    After 2.5 years with new production tubes I'd replace them all. Worst case, you'll end up with good backups.
     
  6. mudster

    mudster High Prairie Wrangler Silver Supporting Member

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    For gain at low volume absolutely try different preamp tubes.
     
  7. Avatar Tech

    Avatar Tech Member

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    I don't know a whole lot about Groove Tubes but I think that their EL84's are re-labeled JJ's. If that's true I personally find new production JJ EL84's to be fairly bright. As others have suggested I'd say just try all new tubes but go with smoother toned tubes across the board. Sovtek EL84's tend to be smoother than JJ in my experience, for example. Maybe someone can verify whether or not I'm right about GT EL84's being rebranded JJ's.

    CD
     
  8. grateful.ed

    grateful.ed Member

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    It may depend how you use your amp.

    I had an AC30CC and dimed the master and dialed the preamp to the volume I wanted, so I would think the power tubes are most of the tone.

    But if I ran it with the Volume dimed and dialed the master to the volume I want, the preamp tubes are most of it.

    but saying that, when I retubed it every year, I always swapped them all.
     
  9. cdntac

    cdntac Member

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    This was my line of thinking as well --- it depends on what tubes are being pushed. I usually run the post gain high and the master volume low.
     
  10. Gearaddict

    Gearaddict Member

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    JJ pre and power, EH pre and power, Sovtek, Ruby and Tungsol preamps new stock all good sounding and durable performance. The really expensive tubes are reserved for the cork sniffing crowd. Not sure about the mid priced tubes like Gold Lion.
     
  11. mcdes

    mcdes Member of no importance

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    :agree
     
  12. EADGBE

    EADGBE Member

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    It made a big difference in both my 60 watt Marshall TSL602 and my Marshall 100 watt 2203X. I went from EIs in the TSL, and another brand in the 2203X to Sovtek 12AX7LPSs. The difference was definitely audible.
     
  13. cdntac

    cdntac Member

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    Yesterday I had called a local guitar shop and they had some EH and PM 12ax7 tubes. He told me that the PM tubes were used by Marshall.

    Got to the store today and someone had bought the EH tubes in the morning. Damn. And the PM tubes weren't high gain.

    But he did have some GT high-gain tubes. I had brought a review/spec sheet that I had found online and though they were rated below the EH tubes (and some others) I bought the two he had. That info came from here: http://www.tubesandmore.com/scripts...clients/cemirror/ELEVATOR.FXP?page=12AX7CHART

    When i got home I found an EH tube that had originally come with the amp (I had swapped tubes soon after getting the amp so it had seen minimal use).

    I tried the GT in V2 and V3 and the EH in V1. With my Byrdland the amp was now very microphonic. I wasn't expecting that!

    So I put the GT tubes in V1 and V2 and a JJ tube in V3. Big difference! The amp wasn't microphonic at all now and was much more responsive.

    After playing with the B, M, T and presence knobs I finally found the combo that I liked and where there was next to no difference between using the OD pedal or not (only a hint of OD ever gets used to open the amp up a bit).

    Neither of the stores I was in had any power tubes for my amp.
     

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