FDP Forum / Blues Jr Billm bias pot install instructions/ 31 messages in thread.

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Apr 11th, 2017 11:57 AM        

I had a tweed Blues Junior that Bill modded for me and it sounded great. He added the tiny pots but after that I never really adjusted them much. I didn't have a bias probe for EL84 size tubes. It seemed to sound great with whatever tubes I put in there with no problems after that. <br /> <br /> I guess what I'm saying is that you might want to just change the resistor values to the values he recommended instead of adding those tiny pots. Either way it was a great improvement. More headroom, clarity and bottom end.


Studio City, CA

Apr 18th, 2017 12:21 PM        

Thanks to Twang and Hammond for sending along the printed cream board instructions. Very sorry to hear about your sciatica.<br /> <br /> Hammond, do you have the info now to do Billm's green board bias pot install? According to an ancient Billm post, "the stock bias resistors in a green board BJr are R31 and R37, 22K and 33K respectively. In the cream board, they're designated R52 and R51, also 22K and 33K respectively." I'd like to get the some new tubes and get the bias control to finish the project. <br /> <br /> Also, the reverb doesn't seem to work since the basic mods. Any ideas?


Studio City, CA

Apr 18th, 2017 12:24 PM        

Thanks for your input, guitarcapo!<br /> <br /> I think I might as well get the bias pot installed since I already have the part.<br /> <br /> I agree that the mods add headroom, clarity and bottom end.<br />


Contributing Member

MT, USA and Jura, FR

Apr 19th, 2017 09:03 PM        

89AmStd,<br /> <br /> If you go to the "waybackmachine" and search on:<br /> <br /> http://home.comcast.net/~machrone/bjr/bjbias.htm<br /> <br /> you will find the directions for the bias pot install on a green board Blues Junior. These are the directions I used years ago, and they work great. <br /> <br /> A major nod to Billm; the Bell Tolls for Us All.


michigan usa

Apr 20th, 2017 05:00 AM        

Nice work!<br /> <br /> Here's the direct link:


Studio City, CA

Apr 24th, 2017 05:54 PM        

Thanks blackandblue for the "wayback" info and to twangs for posting the link! Very cool. I agree that Billm deserves a major nod--he was a good 'un!<br /> <br /> Hammond101, do you have all the info you need to do Billm's green board bias pot install? Please let me know.


Contributing Member

Edmond, OK

Apr 25th, 2017 11:41 AM        

"I've got a 'Clean Boost' mod for a green board. I bought one, then I got Bill to install one. It's in classifieds.


Studio City, CA

May 3rd, 2017 09:04 AM        

Hammond101, do you have all the details needed to do Billm's green board bias pot install for me as well as the bandwidth to complete the project? <br /> <br /> Please let me know if we need to request more info and/or if I need to find another tech to make it happen. Thanks@



May 4th, 2017 10:52 AM        

This is a bit of topic but still in the spirit of the post at least... I was also trying to get ahold of Bill's son about an order with no replies to email, but I found him on Facebook under "BillM Audio" I believe, and he answered in about 30 seconds to a message (your mileage may vary)...<br /> <br /> Just an FYI to anyone needing to get ahold of him.<br /> <br /> Happy Modding!!


Contributing Member

So. Cal. USA

May 9th, 2017 10:00 AM        

Thanks for that info! I messaged Bill's son yesterday through Facebook and got an auto reply however in 30-45 minutes he sent the green board instructions file no questions asked. <br /> <br /> Good to have this method of contact.<br /> <br /> Thanks GK, great suggestion.



Sep 26th, 2017 04:41 PM        

I removed the 33k resistor (R36) and placed a 50k mini pot with a 10k resistor in series in it's place.<br /> The 10k resistor prevents you from going to Zero ohms.<br /> <br /> You only use 1 leg of the pot and the center/wiper.<br /> <br /> Set bias as shown in Bills videos.

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