I uploaded a labeled schematic of the TO-6/TO-6A, click Here to download it.
Was a little worried about my highly modded Fender Blues Jr. I added Siemens (EPCOS) and ELNA SILMIC-II. I also put some vintage orange drops in to go with the newer ones.
However, after I finished installing everything I had no sound. The tubes were heating up and I had voltage across the main PSU cap. I re-flowed any questionable solder joints and stuck with it. After 2 days I had her singing again!
Sorry about the cell camera, somtimes it’s just easier to go with one.
I really like the tone I have now, love my Celestion G12H Greenback speaker with these mods.
(For the curious, the two potentiometers hanging are the sparkle and presence mods from BillM)
Source: Celestion – Frequency Response Curve
This is from my thread on TDPRI, which can be found here if you’d like to see the topic in its original entirety: Click!
Most of this is copied and pasted from there because it was already so detailed and accurate to what is being used. My memory isn’t as good as the Internet!
Mainly this was my first venture into modding audio circuits, besides building BYOC (electric guitar effect pedals) kits and selling them. Working with an amplifier and doing mods is so much better than most of the mods I have done! Hearing the differences you can make is very rewarding, especially when you are doing all the building yourself. I encourage all readers who own a Fender Blues Jr. to try the “basic kit” BillM sells for all versions of the modern Blues Jr models and the Fender Excelsior.
Correction: BillM IS
no longerproviding his mods again, after a hiatus that he took due to health concerns. For a while his son filled the orders, but on their site it sounds like Bill is back at it again. I may reach out to him and see if he wants to team up and let me be the guinea pig for any new mods!
New Article on “BillM”‘s Fender Modding site announcing he is back and working on a backlog of orders:
This is great news for all current and future Fender Blues Jr owner’s! I believe the two or three modern versions of the Blues Junior (made in last 20 years) is the best trade off between tubed audio circuits and their (sometimes superior) solid state equivalent. BillM and his son create some of the best Fender Blues Jr (“BillM”) mod kits for your money by just about any other modern and vintage based guitar amplifier, not counting complete DIY kit amps.
Most mods for tube based electrical equipment will run at quite the premium if for nothing else, LETHAL currents & voltages present in multiple places… Without taking the proper precautions, doing a capacitor upgrade could end with your obituary, seriously. That isn’t a joke and BillM does an excellent job instructing the customer how to build and/or install their kits. The main thing is to make sure you bleed any voltage off that is currently in the power caps.
I purchased the Blues Junior knowing it was pretty much the perfect practice/home amp in the sub $500 range for that classic American tone. After spending some time with it and stumbling through the internet onto BillM’s website (http://billmaudio.com/wp/) I decided to start modding the amp. I have a long history of modding PC’s (even directly soldering on motherboards and video cards along with building custom guitar effects pedals. So I knew this would be a piece of cake with how simple the Blues Jr. is.
I started with some basic BillM mods, this are the list of mods I purchased/installed from BillM:
Basic Cream Kit
Switchcraft Input Jack
Switchcraft Line Out Jack
TO20B Upgraded Output Transformer
After installing all of those mods I was very satisfied with what I had in this is the list of mods I purchased/installed from Bill Ms with all the mods. The only thing still lacking was the bass response from the stock speaker
At that moment in time the “budget” wasn’t the main concern here and you are talking about a $200 speaker upgrade (that could be moved or sold at very little loss).
Here is a breakdown of everything you see in the completed pictures:
Blues Jr. – $429
NOS Tubes – $105
BillM Mods – $91
Speaker – $199
Total – $824
I went with the Celestion G12H Greenback because I have heard them (lol ever listened to Hendrix? ) versus some other 12″ speakers and nothing came close to it in my mind (from what I’ve heard in person). Looking back now I wish I had gotten a used Blues Jr. (since I was going to void the warranty anyway), but you live and learn.
Build Log Comments:
You can see info on a mod I did to the Tempest Custom here.
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