1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

Ampeg SVTDI schematic?

Discussion in 'Pickups & Electronics [BG]' started by bran fraz, Mar 26, 2019.

  1. bran fraz

    bran fraz

    Mar 26, 2019
    I have looked all over the internet to find a schematic for the SVT-DI box. It's a little over 10 years old and is having a bit of trouble with the tube. I've taken it to a professional in Dallas but he also can't find the schematic. And he's never worked on an SVTDI before. Is there someone who knows where I can find the schematic? It's not on the Ampeg website.

    I've tried reaching out to Ampeg customer support and even sent an email to Obeid Khan (the lead engineer with Ampeg when the SVT DI was released). There hasnt been any response from either party.

    I love the DI! I'd love to be able to have it fixed.

    Thanks everyone!
  2. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    Send it to Obeid.
    bran fraz likes this.
  3. bran fraz

    bran fraz

    Mar 26, 2019
    I sent the request to Ampeg and they got right back with me. May I present, for the first time ever on the WWW, the official schematic for the Ampeg SVT DI. I hope other people find this useful as many of the units come to the point where professional servicing is probably needed.

    (SVT direct injection direct in box SVTDI SVT-DI)

    Attached Files:

    Last edited: Mar 27, 2019
    Saint70, Axstar, okabass and 2 others like this.
  4. I drew this out years ago; it doesn't appear that I missed anything in my schematic. However, the measured B+ voltage @ 120V mains input only measured to 257 volts, rather than the 300V Ampeg cited on their schematic.
  5. What sort of problems are you experiencing?
  6. Jeff Scott

    Jeff Scott Rickenbacker guru..........

    Apr 11, 2006
    But, you were measuring from 120V Canadian, right? :D
  7. Yeah, I forgot about the 30% exchange rate. The exchange rate was less when I drew the schematic.
    Axstar likes this.
  8. bran fraz

    bran fraz

    Mar 26, 2019
    I know next to nothing about this stuff. But i took it to a well respected tube amp repair shop in Dallas. Anecdotally, the tube doesnt glow very bright, and light next to tube is out all together. I’m not sure if the tone I’m getting is pure pass through or if it’s being warmed up by the preamp itself. I took to a local shop to diagnose all that, and potentially replace the tube.

    I sent an email to Obeid, and he was so nice to reply back. Had i known about the Khan DI i probably would have just bought a new unit from him instead.
  9. andykeating


    Oct 5, 2016
    Apologies for dredging up a relatively old thread but I’ve just bought one of these SVTDIs. It’s in its way over from Atlanta currently. I’m in the UK and am wondering whether they’re suitable our 230V power, or whether I’ll need a step-down transformer?

    The image I have of it shows two different fuse options, one for 125V and one for 250V which suggests there may be internal switching and you fit the relevant fuse?

    I’ve downloaded the schematic but electronics isn’t really my strong point hence me asking. Thanks in advance.
  10. sheltjo6

    sheltjo6 Supporting Member

    Jun 10, 2012
    Based on the photos, you probably need a step down transformer.

    Attached Files:

  11. andykeating


    Oct 5, 2016
    Just an update to this, for anyone in the thread who may be interested, and anyone who like me, searches for the same info.

    The transformer inside is a multi-tap transformer. Blue wire connected from the transformer to the fuse is 100V, black = 120V, grey/white = 230V and brown = 240V. So was a very simple case of changing the connected wire and that was it. Fuse was a 250V fuse, so no issues there.

    Due to go in the studio to record our second album next week, so will have a better idea of how good the SVTDI is then, but first impressions are very positive. :thumbsup:
    Roxbororob and JimmyM like this.
  12. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

    May 15, 2021

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.