So I'm thinking of retubibg my Fallen Angel. I'm still looking at which tubes to buy, but until I have a vague idea, my main question is about fitting the tubes. Do I just unscrew the old ones and replace them with the new ones? Do I need to bias them?
yes, the tubes just pop out and then you pop the new ones in. the owners manual says the amp is fixed biased which means the bias can't be adjusted. As long as your new tubes fall within the current draw range of the amp you are OK.

I ordered JJ EL84 power tubes, Tung Sol 12AX7, JJ 12AX7, and a couple of Jan Philips 5751 for the preamp tubes and try a few different combinations.

this is what the tube store said about biasing.


9. What does it mean to "bias" the amplifier?
Just like the idle of your car may need adjusting when a major change is done to the engine, new power tubes need their idle (the "bias") adjusted to make sure the amp sounds as good as possible. Some amps do this automatically, but many do not - particularly in the world of guitar amps. Many tube amp owners are unaware of this simple regular service for their amp that will keep it sounding it's absolute best. The bias methods of amplifiers fall into several basic categories:
- fixed bias amplifiers (no bias adjustment potentiometer)
- cathode bias amplifiers
- adjustable bias amplifiers.
Each of these types is unique. Fixed bias amplifiers CAN'T be bias adjusted. These amps (for example, some Fender and Mesa Boogie models) use a fixed resistor to bias the tubes, not a bias pot, and are designed to run with tubes that have a specific current draw (see question 4) and should only use tubes that fall within a certain range. Fortunately, these amps are usually pretty forgiving and will work well with a pretty wide range of tubes. For the best results, specify the make and model of your amp in the "Comments" of your order and we will make sure you get the best tubes for your amp.
Cathode bias amplifiers shouldn't require any adjustments and will work with a wide range of tube plate currents, as the circuit is "self adjusting".
For adjustable bias amplifiers, the amp should be biased by a tech with experience with this procedure. It's not difficult, it doesn't take long, but if you don't know what you're doing you may hurt yourself (amps can give lethal electric shocks even when unplugged, and NO, we're not just saying that to scare you). Also, your amp may sound horrible or cause undue wear and tear on the tubes or power supply. Until you learn how to do it correctly by yourself, it's best to pay a technician a few dollars to do it for you.
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an update on the tube swap. I think there has been a marked improvement with the JJ power tubes and the tung-sol preamp tubes. I am also experimenting with a Jan Philips 5751 in various positions and it sounds good but get a little crackling and will try the 5751 in the V4 position tomorrow. If not I'll go back to the straight tung-sol line which was quieter.

(note: trying tung-sols in my pignose G40 did make noise too, so I tried electro harmonix 12AX7 in V1 and two Jan P 12AT7 and utter silence unless I am playing.)

another thing I did do today was hook up the speaker in my pignose G40 amp to the ashdown like an extension cab. so I had the 12" internal in the Ashdown with my pignose speaker which has a Celestion 10" V10. nice full sound. but when I got home late I thought I'd just run the Ashdown through the 10" speaker to keep the noise down. man, are the cleans sweet this way. seems to reduce the bassiness inherent in the Ashdown. I am thinking a 2x10 cab would work well with the Ashdown.