Two Rock CRS has lost low end and sounds crunchy. New output valves? Re-Bias?

challen

Any ideas? It's the 100w model and it sounds a little dirty, even with with the gain control at very low levels. It sounds as though it's not got the output and massive low end it used to have and I'm not getting those fat, squeaky-cleans anymore!

Thanks!

ICBM

It sounds like one side of the power amp has gone down - possibly the phase inverter, or maybe one power valve and it’s done something meaning the other on the same side isn’t working right. (Just one power valve failure in a 4-valve amp won’t do that.) Or possibly, something in the bias circuit has failed leaving the bias voltage at full up, meaning it’s now biased very cold.

Is the phase inverter valve definitely glowing on both sides? Are all the power valves glowing and/or do any look odd?

Nerine

challen said:

Any ideas? It's the 100w model and it sounds a little dirty, even with with the gain control at very low levels. It sounds as though it's not got the output and massive low end it used to have and I'm not getting those fat, squeaky-cleans anymore!

Thanks!

Is the Reverb still working properly?

challen

ICBM said:

It sounds like one side of the power amp has gone down - possibly the phase inverter, or maybe one power valve and it’s done something meaning the other on the same side isn’t working right. (Just one power valve failure in a 4-valve amp won’t do that.) Or possibly, something in the bias circuit has failed leaving the bias voltage at full up, meaning it’s now biased very cold.

Is the phase inverter valve definitely glowing on both sides? Are all the power valves glowing and/or do any look odd?

I'll fire it up again tomorrow and report back. Thanks for your help!

challen

Nerine said:

challen said:

Any ideas? It's the 100w model and it sounds a little dirty, even with with the gain control at very low levels. It sounds as though it's not got the output and massive low end it used to have and I'm not getting those fat, squeaky-cleans anymore!

Thanks!

Is the Reverb still working properly?

It works but it does get a bit noisy (background hiss) at higher levels - this seems to happen on other amps I own so I'm not sure if it's an issue or not?