Discussion in 'Amps and Cabs [BG]' started by axe, Oct 20, 2003.

  1. axe


    Feb 1, 2003
    Yukon Oklahoma
    I just bought an ampeg svp pro pre-amp off e-bay just got it hooked up with all good cables. But there is a nasty humming buzz that sounds terrible. Do I need to replace the tubes or is this something more severe?
  2. tuBass


    Dec 14, 2002
    Mesquite, Texas
    I bet you cant find a thread on talkbass that doesn't have somebody commenting on how noisy these are. I bought one, and sold it quickly. I find this is not uncommon, and I think this is why you see so many of them on e-bay.
  3. Metal Mitch

    Metal Mitch

    Jul 14, 2003
    There's a mechanical transformer buzz with the SVP-PRO, but it doesn't come through the speakers or DI.

    Run your DI into something you can plug headphones into, you won't hear it. Or use a long cable and move it far enough away from the speaker (like another room), you won't hear it. Or just turn up loud enough that you don't hear it. :D

    [/megaphone on]
    Pick up the bass, and step away from the SVP!
    [/megaphone off]
  4. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    I agree, 90% of them are terribly noisy, too noisy to use for recording. Don't know what it is, but it sure is a "widely believed fact". ;)
  5. I agree that they do make noise, but I never noticed an unusual amount of noise coming through my rig when I used the svp-pro. You may want to try swapping out the tubes as they may have been banged around alot during the shipping. If I am not mistaken, there are 5 tubes in the the thing, 4 12ax7s and 1 au7's (?) as the "drive" tube. They do sound very good when all the tubes are in good working condition.

  6. Schwinn


    Dec 4, 2002
    Sarasota, FL
    Pretty much every thread here on the SVP will give you ideas on how to reduce noise. Replacing the tubes should be the first thing you do. It's picky about tubes. Search the site for Lord Valve's number. He's familiar with the problem and can set you up with better tubes.
  7. xyllion

    xyllion Supporting Member Commercial User

    Jan 14, 2003
    San Jose, CA, USA
    Owner, Looperlative Audio Products
    I have an SVT-IIP on its way to me. Does it suffer any of the same problems as the SVP Pro?
  8. Except for it being noisy, it is one of the best live pre's you could ever use. Can you say, tone?

    Tasty tasty tone.
    jazzbass_5 likes this.
  9. Schwinn


    Dec 4, 2002
    Sarasota, FL
    People say that the SVP is not in the same league as Aguilar, Kern, and Demeter, which I'm sure is true, but the SVP gives my exactly the kind of tone I'm going for so I'm a happy camper.
    jazzbass_5 likes this.
  10. axe


    Feb 1, 2003
    Yukon Oklahoma
    Thanx for the help. I will see about getting new tubes put in.
  11. Fuzzbass

    Fuzzbass P5 with overdrive Gold Supporting Member

    I bought a Lord Valve retubed SVP from boogiebass, and while it is a bit noisier than my very quiet Alembic F2B, this SVP is still plenty quiet for live use.

    As for being in the same league with Aggie/Kern/Dem: no, it isn't, but then it isn't priced in that same league either! As mentioned many times, with proper tubes the SVP should work fine. If you like the Ampeg tone and don't mind a little more noise, then there's nothing wrong with choosing Ampeg over the higher-priced models. Sometimes I use Alembic, sometimes I go with Ampeg... depends on my mood.
  12. The fan on my poweramp is far noisier than anything coming out of my SVP pre when I'm not playing. In fact I don't think there's any hum whatsoever from it.
    jazzbass_5 likes this.
  13. Metal Mitch

    Metal Mitch

    Jul 14, 2003
    Open mouth, insert foot... ok I plugged straight into my SVP-PRO (instead of going thru my pedalboard with distortion), turned it up pretty high while not playing, put ear next to speaker, and lo and behold there is in fact a horrid buzzing noise. I had to turn it up pretty high to hear it, so I don't know if a LV retube would help or if that's as good as it gets.
  14. Schwinn


    Dec 4, 2002
    Sarasota, FL might be as good as it gets. If you crank the volume you will hear noise, but it shouldn't be audible while you're playing. LV said that there is a design issue with the preamp, but that the right tubes can only minimize it. Other amps that I've used get real noisy when the volume is cranked up anyway....
  15. Mike A

    Mike A

    Oct 3, 2002
    FWIW, I picked up an SVP Pro from Reasonbass here on TB, and never had any noise issues at all with it.
    jazzbass_5 likes this.
  16. ibanezroadster


    Apr 9, 2012
    The problem everyone is discussing is with out a doubt a earth problem. What the issue is a potential difference in your earth between the preamp and the power amp. What verified this to me was the guys who use the di output don't suffer from this hum. This because there is a isolating transformer between them and the signal. All you need to fix the issue is to purchase a good quality. and lots of car audio stores stock them. A good Earth loop isolator and use this between the preamp and the power amp. Problem solved.
  17. Hi.

    Just out of curiosity, are You on some kind of a quest?

    To find all SVP threads proposing the same fix?
    Which even isn't a fix IMO.

    Or just very bored and desperately seeking attention?

    If the latter, You got mine :)

    JackANSI likes this.
  18. Right? I was wondering why 9 out of the 20 threads on the front page we're about svp pro. Haha.
  19. Omg it's like an Ampeg generated forum robot... ALARM !
  20. PortoBass


    Dec 14, 2016
    Hi all, I'm a new guy on this forum and don't speak very well in English but.... finally found on my SVP-PRO the reason of the buzz, noise, hisss issue. No information is available on any forum about this solution and believe me,,, the noise floor is actualy below -95db with GAIN AND MASTER set to max. Two days ago I found the svp pro schematic on web and this morning I've found a little mistake on the diagram ... and this mistake was in my unit as well... if you looking carefully on schematic you can see that all tube heaters are NOT REGULATED... heaters are connected before the VOLTAGE regulators...that mean heaters are driven by AC VOLTAGE rather than D.C. VOLTAGE. (Way more noisy with AC VOLTAGE)
    I did the little mod into my unit ( 4 little wires ) add a capacitor to remove extra noise to the heaters and now ------ quiet SVP-PRO :). I can provide pictures on request. Cheers !!!
    GtenderG likes this.
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