Ampeg SVT-VR Issue

[dw1003]

I recently purchased a used Ampeg SVT VR

It sounds great, but I'm getting some intermittent distortion/flabby/farty kind of sound.

I believe that I may need to change the driver tubes.

I did a test with the pre-amp out and I wasn't getting the farty sound (from the pre-amp section)

I also did a test with the power amp section only and I was still getting the noise.

Power tubes look like they are acting fine.

the bias looks correct (via the light indicators, both green, balance orange)

Any suggestions?

Thanks

 

[depalm]

The only suggestion is: Get this amp serviced by a pro.

 

[dw1003]

just wondering if anyone has experience with noisy driver tubes in this amp?

Taking it to a tech is a helpful suggestion. thank you.

 

[JimmyM]

The only suggestion is: Get this amp serviced by a pro.

Not for this. This definitely sounds like a tube issue and consumers can easily fix them.

It's very possible a driver or power tube is out. Pretty sure you can rule out the pre. Swap your tubes out with a known good one one at a time. Most of the time it's only one tube out, although now and then it's more than one.

 

[dw1003]

thanks, I ordered a whole new set of JJ preamp tubes 12AX7's and 12AU7's as I'm leaving for tour soon and I need spares anyway. Should be able to test it in a few days.

I've had power tubes go out on me before with other amps, and this didn't really sound like a power tube. This is my first SVT VR and don't have much experience with those driver tubes... hence the inquiry.

The VR manual says those driver tubes get worked really hard, so I'm hoping it's just one of those guys.

 

[JimmyM]

Probably is, then. Keep us posted.