SVT-CL Crackling at Higher Volumes / HELP!

[StormeeBee]

Hey All,

I've got a friend's SVT-CL and there is an issue where, at higher volumes, the amp distorts pretty bad and the signal seems weak. Here's what we know:

- New tubes (Matched sextet of Tung Sol 6550's). Issue was before retubing as well.

- Head is run via speakon to Ampeg 810E (Previously tested and works fine).

- Biasing lights can be turned ALL the way up without turning red.

- Checked cables and tried with different basses. Issue is always the same.

- Gain and Master are at 6 when it starts to crap out.

Any help would be amazing. Local repair guys like to charge $300.00 or better just to check sometimes.

All the Best,
Stormee Bee

 

[coreyfyfe]

Gain and master at 6 through an 8x10 and you're not deaf? That should be pretty loud. Have you checked the PI/driver tubes? Could be that one or both of these are starting to go. The manual says the longer the green lights stay on before going red the better matched the tubes are, but if you can't get the red lights to come on you may have an issue with the bias system.

Hard to trouble shoot problems like this over the internet. What kind of power tubes were put in for replacements? Sounds like a weak signal could be being passed into the power amp if you can turn up that loud and not have it be super loud.