Ampeg svt 3 pro distortion?

[ianhiding]

I've been using my SVT 3-pro for about 5 months now. Recently, I started noticing a distortion with some volume loss. I used to be on the same sound level with the band, now I find myself turning up, up up.

I went to troubleshooting, and believe it is the amp head. I took pedals out of the equation, changed instrument cables, changed speaker cables to my cabs. Still the same distortion. Hooked to either cab solo, same distortion. Tried tweaking settings but really nothing has changed on the bass or amp head. Checked battery for my pickups. My bass on another combo amp sounds fine. Could it possible be one of the tubes? Any ideas? Thanks.

 

[warnergt]

I had a tube go bad on my SVT-3 PRO and it took out a resistor.
My symptoms roughly fit your symptoms but I could smell that something
had smoked, too.
Also, my SVT-3 PRO was about six months old.

 

[B-string]

A failed tube is always possible.

 

[meatwad]

Search for info on biasing the power section. Not for the average joe to attempt, I understand...

 

[tcbass4ever]

i had a similar problem with mine,i replaced the pre amp tubes all of them.i was reading an article about bass players buying these amps and having to replace the tubes a week or two down the road and some of them right out of the box,i would try that if you have had the amp for sometime it wont hurt anything or just bring it in to someone you can trust and let them check it out before you spend all kinds of money!

 

[ianhiding]

Thanks for the replies. How do I know which tube has gone bad? I have looked at the tubes. They all seem to be glowing. The 1 12au7 seems to be dimmer than the other ones. Also, what is a good tube to put in there?

 

[B-string]

You can't tell the condition of a tube by looking at it (unless it is the very rare case of a burned out heater). A tube tester may help, but even those can't tell the whole story. Sub'ing out or tracing with a scope is the best way.

 

[fenderthrupeave]

tube is going out. I just had the same thing happen with my SVT 3. ordered a new driver tube and should be all good. Or atleast thats all I hope that went out.

 

[JustOpenYourMind]

Ampeg has a 5 year waranty for those kinds things, bring it to a any dealer, and they'll find and fix the problem for you, free of charge

 

[warnergt]

Yeah, but the Ampeg warranty only covers tubes for 90 days.
Regardless, you should be able to get it fixed under warranty for cheap.
I had to pay about $10 for the bad tube for a warranty repair.