Ampeg SVTDI schematic?

[bran fraz]

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!

 

[JimmyM]

Send it to Obeid.

 

[bran fraz]

Send it to Obeid.

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)

 

[byacey]

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.

 

[byacey]

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!

What sort of problems are you experiencing?

 

[Jeff Scott]

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.

But, you were measuring from 120V Canadian, right?

 

[byacey]

But, you were measuring from 120V Canadian, right?

Yeah, I forgot about the 30% exchange rate. The exchange rate was less when I drew the schematic.

 

[bran fraz]

What sort of problems are you experiencing?

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.

 

[andykeating]

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.

 

[sheltjo6]

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.

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

 

[andykeating]

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.