Ampeg SVT 3 PRO Help!

[bassplyr1960]

Ok, here's my set-up: Svt 3 Pro re-tubed w/ 4 Sovtek 12AX7-LP's and 1 Tungsol JTL-12AU7. Head fried at a gig ( shut down I should say ) and brought it to a "Ampeg Certified" repair shop. Was told 3 of the 5 transistors fried and had to be replaced. No problem. Got it back sounded great ( I use a USA SVT-210-HE loaded w/ 2 new Eminence Legend BP-102-4 speakers wired in series, ans a USA SVT-15-E w/ a new Eminence Legend CB-15 ). After a while I started getting a growly/fuzzy tone, instead of a nice, tight punchy sound. What I'm asking is should I start looking at the tubes first, or do I need that dreaded Mosfet bias adjustment that I've read about. Any input would be a great help! Thanks.

 

[JimmyM]

if you have a couple spare tubes that are known to work, try swapping them around. otherwise, yep, it's that dreaded mosfet rebiasing. fortunately it's not too expensive to get that done. most places will only charge you a minimum bench charge.

 

[bassplyr1960]

Thank you Jimmy. Most appreciated!