[igot_theblues]

Hello Everyone,
Can anyone tell me if a Hot Rod Deluxe amp needs to be rebiased with a tube change, or is it fixed? Thanks.

 

[zdogma]

It is a "fixed" adjustable bias (with an internal bias pot)

Here's a link, scroll way down, and there are good instructions and diagrams.
If the tubes are the same brand and type, the bias SHOULD be close, but it not a bad idea to check. Certainly you should if you're changing brands or tube type. I like the USA made Groove Tubes in the blues deluxe, and the JJ's 6L6's are very good for half the price. With groove tubes and the tube store you can buy "rated" tubes, if you buy the same tube in the future, and you like it, you can swap in a new set of the same rating without a rebias. Also nice if you blow a tube at a gig, you can swap tubes with a spare set, and still get the same sound.

http://studentweb.eku.edu/justin_holton/bias.html

 

[Wild Bill]

Hello Everyone,
Can anyone tell me if a Hot Rod Deluxe amp needs to be rebiased with a tube change, or is it fixed? Thanks.

You were right to ask. Hot Rod Deluxes, Blues Deluxes, DeVilles...they're all in the same family and some even share the same circuit board. They just don't use all the same parts of it in the different amps.

Some have a bias adjustment and some are fixed at a certain point the factory considered safe enough that they would't have to replace any tubes during warranty. Unfortunately, that usually means the tubes don't put out the tone they should at such settings.

Anyhow, YOUR amp does have a bias adjust! Absolutely it should be set every output tube change. I wouldn't just set it to the factory setting marked on the schematic, 'though. I'd measure the plate voltage and calculate the bias setting for myself, just to be sure. Any good tech knows what this means and could do it for you.

Have fun!:food-smiley-004: