Re: My new amp!

[Randy Lilleston <randyl@xxxxxxxxxx>]

On Wed, 12 Oct 1994, Barry Schaede wrote:

> I'd have to agree about the Bassman reeissue speakers.  Harsh when new is 
> a major understatement.  You could drive nails at 50 yards when this amp 
> is new.  They do get better they don't get good.  I think the other 
> problem with the B-man RI is the stock output transformer that fender 
> uses.  It's bobbin wound not paper core and the efficency is way lower 
> than an older transformers would be.  The other obvious thing to do with 
> the Bassman is pitch the solid state rectifier and replace it with a 
> 5U4GB rectifier tube.  FJM

I think this is a terrific post, Barry. You hit all the reissue problems 
right on the head, except I think you'd be surprised how much better the 
amps sound when they get "broken in." I've had several harp players try 
to buy mine off me at gigs, and I just turned down an excellent price on 
an old Fender Concert to keep my Bassman reissue.

 The output transformer is a good point. Fender switched it because the 
paper core transformers aren't made any more, except by expensive special 
arrangement. There's a reason for that - they're less reliable - but they 
do affect the sound.

 Everyone says to replace the transistor rectifier with a 5U4GB tube but 
that really drops the voltage across the output tubes. If you're going to do 
that, you'd better 
have the amp re-biased, which is a pain in the butt on the reissue 
because it involves removing a resistor from the circuit board and 
replacing it with another one. Actually, I've had better luck with a 5AR4 
tube, which is what was in the original Bassman used.

 Another trick: Try replacing the 12AX7A pre-amp tube closest to the 
big output tubes (the "phase inverter" tube) with a 12AT7. I found this 
really cuts and controls feedback, allowing you to "crank" the amp more 
and get better post-amp distortion. However, many people feel this 
affects the tone. Pre-amp tubes are cheap - you can always try it and see 
how you feel about it. I've even known some harp players who have 
replaced all three 12AX7A tubes with 12AT7's. I did this for a while and 
it made the amp very controllable, but I decided it affected my tone too 
much.