Originally Posted by gomestar
ah, gotchya. I wasn't fully aware of the technology there. Cool that each socket will re-bias automatically according to the tube.
Would the full voltage mean that it's effectively running each tube as if pre-amp was turned to 11 and power amp was turned to 11 at all times? I can see that eating up tubes like crazy, even if you only play 1-2 hours a day. On the flip side, you don't need 4 6L6's just to get the thing back to running.
It sounds like, and correct me if i'm wrong, it's taking the signal from the guitar, amplifying it to the fullest via pre-amp tubes and then power tubes, and then taking this very full singnal and cutting the output without altering the tone like an attenuator would.
To answer this I need to explain some things about bias in amps.Fixed bias
does not = a constant bias for all tubes. It merely means that the bias on the amp is meant to stay the same unless you change output tubes. In this case, the Fargen is fixed bias. It does technically change the bias for different tubes. A lot of Marshall amps are technically fixed bias. They contain a bias adjustment pot for when you change tube brands.
An actual fixed bias where the bias never changes in the amp is called Cathode biased
. A Vox AC30 for example is cathode biased. The idea here is you take an EL84 tube and run it hot as hell ALL THE TIME and it will sound amazing from all the bloom and breakup.
The Fargen is advertised as Class A but that is sort of misleading because a lot of people when they think Class A also think Cathode biased, and the Fargen is not. However, the Fargen (I would assume) does set its bias points on each tube to run fairly hot, because if you are going to use the attenuator on it, you want your tubes to stay hot and keep that saturation.
Any time you have an amp running an unusual wattage for its tube (12 watts for a KT66 is retarded) or using a power attenuator, you are going to damage the tubes to some degree, one way or another.
Basically with the Fargen, you can turn the volume all the way up to get that super crunch and then lower the volume with the attenuator...but it's still running on full and burning the hell out of those tubes.