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Trace V8 DI Hum/noise.

Discussion in 'Amps and Cabs [BG]' started by popinfresh, Nov 26, 2005.

  1. popinfresh


    Dec 23, 2004
    Melbourne, Aus
    Hey guys, i'm gonna order some new pre tubes in the next few days so thought I might as well get this sorted at the same time..

    When using the DI on the V8, there's a lot of hum coming out of the PA, especially when I use gain II and it's on post EQ.
    Also, when I turn up the master, there's quite a bit of hum and noise. I've also noticed when playing in my bedroom that when I use gain II and sit facing away from the amp, there's a lot of buzz as well (still is when I face the amp, just more when I face away), which I suppose would be grounding issue of some sort?

    Anyway, just wondering if one of the preamp tubes (especially the DI/gain II factor) would be causing this? If so, any of the V8 owners know which one, so I could replace it?
    Also, could the grounding issue in my room etc be a dodgy cable perhaps? At a battle last year, the bass amp (not mine) fell from a stack about 5' high and bent the end of my planet waves lead, the shop nearby replaced it with a cheap-o jack end and i've used it ever since. Could that cheap end be an issue (never really had a problem with my other amp though).

  2. popinfresh


    Dec 23, 2004
    Melbourne, Aus
    Oh, and I havn't had it biased since I got it.. So should i get that done soon? I've really got no money (stretching it for a couple more tubes) so how much should it cost to get it done? Or can I do it myself easy enough? The power tubes havn't shown any sign of failing BTW, though one still tinkers/rattles in there somewhere (can't figure out which).
  3. el_Kabong


    Jul 11, 2005
    I had one of the hybrid V types, tube pre & ss power. I might be wrong but I think the preamp in those is similar to yours?? Mine had a noisy di too and TE released a fix for it. I might still have it stashed away somewhere, I could dig it out if you think it might be useful?
  4. The hum is your bass. Its pickups are humming from the magnetic field generated by the amp's power transformer. Your bass needs better shielding. The extra gain boost is magnifying the problem, not necessarily causing it. Improper bias CAN cause hum but it's usually independent of volume.
  5. popinfresh


    Dec 23, 2004
    Melbourne, Aus
    Hmm, what about the DI noise then? That still hums even with other peoples basses or no basse's plugged in at all (i'm pretty sure it does it in standby anyway, or at least when everything is turned down).

    el_Kabong, that could be helpfull. If you could find it, let me know!
  6. The DI hum is a separate issue, mostly likely bad grounding somewhere in the DI itself. If Trace has a fix for the ss power section V-Type, chances are good your V8 may have the same problem. You can try telescoping the ground (lifting on the "amp" end) at your PA connection and see if that helps.
  7. el_Kabong


    Jul 11, 2005
    PM me your email address Pop and I'll send you a scan of the doco. I've got a schematic of my old preamp too so you can compare and see if it applies to your amp. It actually says 'Every v-type preamp (including those fitted in amps), requires this mod as the hum from the di is unacceptable in any application'. Sounds like it might do the trick.
  8. Hey, im, err, qualified in fixing V8's, send it to me and i'll. err, fix it :)
  9. Hmmm. I've had no issues with a noisy or humming DI on my V8. I use it with the pre-eq setting though. My post sound comes from my miced cabs. Let's hope you get it sorted out!
  10. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    Fremont, Ohio
    Editor-in-Chief, Bass Gear Magazine

    I've had no such hum/noise issues with my V8 - DI or otherwise. As for the schematic and service manual, I should have e-mailed that to you shortly after I added you to the "V8 Users Support Group." If you don't have it, either check www.britishaudioservice.com or send me an e-mail and I'll resend it. As I recall, the DI output is related to one of the stages of either v7 or v8.