Tube Questions

Discussion in 'Amps and Cabs [BG]' started by tufnuts, Jul 17, 2001.

  1. Hi all. I wanted to see what everyone's opinions are on changing preamp tubes. I've got a Hartke 3500, and will be recieving a SWR Grandprix. I'll possibly also buy a ampeg SVP Pro.

    I've also been doing some research for myself and friends on tube preamps. It's suggested to replace 12AX7's with 5751's. I can see where they are coming from, with the 5751's being a bit better constructed, less microharmonics..etc. All the research I've done points to Sylvania JHS/CCA ones. I was thinkin about buyin a few of each brand, testing them out in both rigs.

    So my question. Anyone ever retubed a Hartke, SWR GP, SVP Pro (What tubes come in the SVP Pro anyway?) And had some success at it? Any recommendations? I've also never yanked and replaced a tube, but it can't be too hard. Any suggestions/cautions?

    Thanks, and I know it's all personally subjective. Everyone's ears are different. I'm talking a distinct advantage, if that's even possible.
  2. Truth be told, you're probably not going to hear a whole lot of difference.
  3. Yep, maybe a tiny difference, but even most of that is psychological, assuming there is nothing wrong with one of the tubes being compared.

    You may get less noise with one or the other, more or less microphonics, and a little more gain with one, but nothing major. You'll have less gain with the 5751 by design.

    It's easy to swap em out. Hardest part is figuring out how to get to them on modern amps. Grab the top, gently swirl it around just a little while pulling up. Insert by straight pushing it down, no swirly needed. :D

    Did I mention that they get hot while on?

  4. Yes, I know they get hot...shhhhesshhhhhhhhhh :)

    I was just looking for a little fun cheap project to do in between all the costy stuff (Building another cab, 4x10; Building a warmoth J bass, putting together and tuning a rack system) But I've never really liked the tube side of the Hartke (kinda shrill, poppy, needs to be subdued). So if I can get it to sound how I want, I'll keep it. If not, it's up for sale. I'll prolly just record a dry signal of me playing, then put it through the hartke, then record it on the minidisc. That way I can do a fair comparision.
  5. I use a Sylvania long black plate, 3 mica spacer JAN 5751 and it makes a noticeable improvement to the stock Groove Tubes 12AX7A in my SWR.

    When overdriven from the front end it's very smooth and musical. Very vocal.
  6. coyoteboy

    coyoteboy easy there, Ned Supporting Member

    Mar 29, 2000
    Sactomato, CA
    I heard good things from tube techs about the JJ/Tesla 12AX7S. I am in the middle of doing some tube work in my aguilar stuff, and I think I'll be going with the JJ's in the pre and ( if I can save enough money) a set of JJ KT88's for the power. has good prices on the JJ tubes.