Tube experiences w/Ampeg SVP Pro Preamp?

Discussion in 'Amps and Cabs [BG]' started by CzarMike, Sep 20, 2002.

  1. What are the best tubes to use with the Ampeg SVP Pro preamp? It has some real cheap-o's in there from the factory and I notice a slight bit of noise. My SVP uses four Sovtek 12ax7wa's and one unmarked 12au7. I'd like to hear suggestions on personal experiences with different tubes in this preamp.
    Mike S

    p.s. I play rock, with little to no use for very high frequencies (no slap, etc). This makes it hard to read reviews for tubes aimed at g***** players.
  2. I got ahold of a mix of old and brand new 12ax7's, 12at7's and 12au7's and here's what I found.
    This is the summary of like two hours of fiddling with different tubes and different orders.
    From left to right:
    1. Groove tubes 12ax7
    2. NOS Phillips ECG 12ax7
    3. Groove Tubes 12ax7
    4. Unmarked "made in china" 12au7 (read below)
    5. NOS Phillips ECG 12ax7
      I also tried out some brand new Electro Harmonix 12ax7eh's in there, but didn't really like them as much as the Groove tubes (that suprised me). I also tried putting a really nice PhillipsECG 12at7 in place of that crappy generic 12au7 that is in there from the factory, but I think that was to much gain or something, it just didn't sit right with my ears. I also tried each of the 12ax7's in that position and none gave the bass that rounded sound that came from the 12au7. I have a NOS Mullard 12au7 coming off ebay, I'm thinking that should really do the trick.
      Anyone else not like the Electro Harmonix 12ax7eh tubes? I loved them in my traynor yba-1 head, but they barely even glow in the SVP (does the amount of glowing a tube does affect it's sound at all?)

      I found that the biggest tonal difference comes from the first position tube (far left). If you place a low noise, high gain tube there it just really brings the preamp to life. I'm going to be keeping my eyes open for a really really nice old 12ax7 for that position off ebay. Also, the higher microphonic tubes (like my beautiful Phillips 12ax7's), don't seem to add any noise when placed in the positions I have mentioned. Is there a name for this phenomenon?

      Rock On,
  3. I've got it in my head to replace the tubes in my SVP-pro (Seems like there's a lot of SVP users on here), and that info helps tremendously.

    Thanks! I'll start scouting around for some tubes.
  4. Chuck M

    Chuck M Supporting Member

    May 2, 2000
    San Antonio, Texas
    I had an SVP-PRO. I loved the tone of the preamp but it was quite noisy. I installed new tubes in it and that just made it worse. Some have suggested that it is other components used in the SVP that tend to make them noisy. The DI on mine was not usable because of noise so I traded it off.

    I'm a tube addict and have a lot of NOS tubes in stock at fair prices. I don't make much money at it but it is fun helping other bassists improve their tone for cheap. Hey, even expensive tubes are cheap compared to cabinets, amps and such.

    Feel free to contact me about the tubes I have for sale.

  5. seamus


    Feb 8, 2001

    curious to see what others are using

    I have the EH's in mine. I'm pleased enough with those for now, they are pretty quiet, and they break up nicely.
  6. submelodic


    Feb 7, 2002
    Seattle, WA
    I replaced the originals with EH's too. It's a little better, but I'm on the fence as to whether or not the SVP-Pro is the right pre for me. I'm still experimenting with it during rehearsals.

    BTW, I started a similar thread a short while ago:
  7. incubus2432


    Mar 21, 2002
    Grafton, Ohio
    I just went with Groove Tube replacements and am happy enough (4 12ax7's and 1 12au7 in the "as factory" positions). With my cabs, Rics, amp and effects it gives the exact sound I was after. I've noticed no noise issues.....but then again I love Lemmy's tone:eek: :D
  8. Here's an update with what I consider to be my favorite tube setup for the SVP, after a few more hours of piddling around and spending some dough on the net.
    from left to right:
    Amperex 12ax7a, Groove Tubes 12ax7, PhillipsECG 12ax7, Mullard 12au7, PhillipsECG 12ax7

    I found the Amperex in the stockpile of 1500 NOS tubes I bought last week, it says it is made by the Phillips company in Great Britian, leading me to believe it is similar to a Mullard. It's a huge, beautiful 12ax7 with a great voice. The Mullard 12AU7 was a big help as well, getting rid of the generic chinese one should be on every owner's to-do list.

    Anybody else have any cool tube combos for the SVP? BTW, I should have my online tube store running within the next couple of weeks:
    I'll give anyone from this thread 10% off if you mention it.
    rock on,
  9. resurrect..... Whatever happened to that site?
  10. jimbilly


    Apr 19, 2006
    I've tried a few different combos, and I always end up with some line-noise, -I'm frustrated with my svp right now. Currently I'm running all old RCA red-tip black plate 12ax7s, -those were picked by RCA as the lowest noise tubes they had. I've got some Mullards I ran in there too, Tung Sols, etc.,, 12au7s just seem to lower the gain and output and don't seem to do anything to the line-noise.
    As far as tone goes, IMO any good old tube is going to sound warmer than current production.
  11. Yeah that TUBEBANK site is a good 'un eh??????????????????
  12. JimB52

    JimB52 User Gold Supporting Member

    May 24, 2007
    East Coast
    I'm using Chuck M's old SVP I think. Doesn't seem noisy to me, and I've never used the DI on it. Nice tone, but I prefer the Sunn 300T.
    Jim B
  13. jimbilly


    Apr 19, 2006
    Mine only seems to do a hiss through the house, -so I guess it's not really MY problem!
    In my experience with tube swapping, newer production tubes (chinese/russian) seem to have a harsher, more aggressive tone. I like the smoother sounds of the older tubes. I guess if you're playing hard rock +, you might well prefer the Chinese tubes.
  14. Thanks for the tip. I archived it in the Ampeg section of my library.

    V1 - JJ Tesla ECC83S (12ax7)
    V2 - " " "
    V3 - " " "
    V4 - JJ Tesla ECC82 (12au7)
    V5 - ElectroHarmonix 12au7a/ECC82EH

    I recently acquired an SVP-Pro, but have not had free time to fool with it yet. If I have a hissing problem, I'll try your arrangement and see how it works:
  15. Fuzzbass

    Fuzzbass P5 with overdrive Supporting Member

    I bought my Ampeg SVP-Pro used. It had been retubed by its previous owner. It's not as quiet as my high-dollar preamps, but even at the gig, noise isn't significant.

    Here's how it was retubed. Nothing fancy, I don't think:
    • 4 ea NOS Bejing Production Chinese Grayplate 12AX7's,
    • 1 ea NOS Philips JAN 5814 (12AU7).
  16. Out of the box mine was so noisy it was unusable. I kept it around past the warranty on the tubes (dumb) and then I had it sent back to Ampeg to fix the noise problem. It came back with a bill for $125.00 all new tubes and dead silent. I guess it was worth it. I'm afraid to mess with it, afraid the noise will come back.