$300 blonde BJ day!!!

[tunghaichuan]

I did three of the BillM mods on my Blues Junior and liked them all--

• The "Simple/Adjustable" Bias mod: I e-mailed Bill and asked if he had instructions to do an in-between mod for tube bias. I didn't see a need for being able to adjust both power tube bias values independently, but I wanted more control than just soldering in a replacement resistor for R52. Sure enough, he had instructions for a single trimpot installation that lets you adjust the bias for both tubes simultaneously. Much simpler installation than the dual-pot mod! Since most of us buy power tubes in matched pairs anyway, this seemed more than adequate to me. If anybody wants a copy, PM me and I'll e-mail it to you. It's for the newer (mid-2001 and later) version of the BJr, with the cream-colored PCB.

IMHO, there really is no reason to match power tubes in a guitar amp circuit. Just buy a matched set from a repuatable dealer. I've heard some techs say that guitar amps sound better with slightly mismatched tubes (5-10mA). Besides, Fender used to just grab two or four tubes and stick them in the amp and called it good. They didn't worry about matching. Although at the time, RCA Blackplate tubes were readily available and they were made to much tighter tolerances than modern production tubes.

The only advantage I can see for the individual biasing scheme is if you have two tubes that are way mismatched.

Also keep in mind that the individual tubes do age differently, even ones from the same batch.

tung

 

[ShortBuSX]

The only advantage I can see for the individual biasing scheme is if you have two tubes that are way mismatched.

Bill's site suggests its good if the tubes are too well matched as well...like if you wanted that slightly mismatched tone. :thwap:

 

[Tone2TheBone]

I have a Blues Junior with a couple of the Billm mods too. I bought the amp from some guy who did the cool mod with the one resistor swap. It's a lot clearer sounding from a stock BJ with that mod. I myself did the twin stack. Easy to do and makes the mid knob more useable. I also swapped out the stock Eminence for 2 speaker choices...one being the Jensen C12N and the other a Warehouse Guitar Speakers Veteran 30 (a Celestion Vintage 30 knockoff). I agree that the Jensen C12N produces absurdly good Fender clean tones but I found for my purposes that I prefer the sound of the WGS Veteran 30 because I like to play with some overdrive and all out distortion and the Jensen (to my ears) was too shrill. Anyway FWIW....

 

[ShortBuSX]

Im glad to finally see some BJr talk...I knew a couple of yall had em, but the BJr doesnt seem to get much love here at the fret

Seems like were all in agreement about the mods to do...looks like Ive got the right plan.

Speaker changes, but no tube swaps?

And mine was the only one with a bum reverb???

 

[Tone2TheBone]

Im glad to finally see some BJr talk...I knew a couple of yall had em, but the BJr doesnt seem to get much love here at the fret

Seems like were all in agreement about the mods to do...looks like Ive got the right plan.

Speaker changes, but no tube swaps?

And mine was the only one with a bum reverb???

I have lots of love for mine. It loves me back when the amp's pushing past halfway on both the volume and master. Forgot to mention that I have J&J tubes in it. Both power and preamp tubes. Also forgot to mention mine is an American made green board Blues Junior.

 

[ShortBuSX]

Took my BJr in on Friday to my tech.
I had him do the TwinStack mod and had him cool the bias down by replacing a resistor.
Works great, cleaned up the tone considerably, but its taking me a minute to get used to the tone stack.
Cost me $40 and I got it back on Saturday...this guy rocks:AOK: