Excellent review, thank you. Studying electronics for 2 years and this really helps. Love my Blues Junior III. I did some great mods.

Thanks! Best explaination I've seen so far of what all the niddly bits do. My next build will be an Ampeg SB-12, and quite a bit of what you presented will be applicable to that schematic as well. It'll just take me awhile to sort it out...

Great walkthrough! I do really appreciate it!

I just love all the babbling and singing from your toddler! :) Yes a bit invasive but that's a sign of good health and you seem to be a patient dad. I'm glad you left all this funny noise in the VDO, and also, the demonstration was brilliant!

Thanks for making this Video. Very informative. Great blues Jr Schematic breakdown. I knew it sounded thin because of the low value input cap, fender also these low values also used these small values on its solid state amps and they sound thin. Its not on my to do mods list along with upgrading the tone stack to a more fender classic style. Thanks again!

Great video for anyone thinking about modding a Fender Blues Jr.Although circuit overview should have been done with the schematic for Blues Jr II & III.The position of Volume pot and the tone stack resembles the Fender Bassman so nothing new there.I wouldn't use a 1k pot for bass instead I would use a 1 meg pot just like the Bassman. I can tell you from experience that the best mod for the Blues junior is a 6V6 conversion along with other mods mentioned in this video plus some other mods. The amp sounds fuller and drives the speaker better with 6V6 output tubes. It got a mojo that it didn't have before the mods. Nevertheless I still felt that I needed better cleans and wattage after the mods for gigs especially since I was not miking my amp. Once i got the Fender Deluxe Reverb 68 I sold my modded Blues Jr and I never looked back.I also got a Fender Silverface Champ which sounds better than the stock Blues Jr .If I have to do it all over again I would probably buy a Silverface Champ for home practice or a 65 Fender Pricenton Reverb if I needed more volume. If I wanted to buy another Blues Junior for modding I would find a used one for $250.

Brother this was awesome!! Thank you

I enjoyed this! And not being snarky here - but thanks for not acknowledging your child making noise every 5 seconds. It’s what kids do and it’s not that big of a deal.

20:30 Joy to the World? Christmas was a month ago!

Hi mate that was very informative, I’m from mechanic background and have been added some Billm mods to my blues junior, if this was a hydraulic machine I’d be fine. I have dabbled with electronics over the year so I have a very basic understanding, having you walk through the circuit was great, I was able to follow quite well. I would have loved to hear your explanation of the reverb circuit, mine is not working and it’s driving me mad trying to work it out..

I like the idea of making an biasing pot 18:30. I wanted to do that to my Magnatone M10 which also runs EL84. Enjoyed your vid. Thanks for sharing. c];-)

Great circuit analysis. Do you the same for Hot Rod Deluxe !!

This is very interesting to me. Thank you for this. Is this the model 3 or model 4 version?

Thank you for providing us the best BJ modding tutorial with deep explanations. My question is about improving/increasing the reverb effect in an early green board BJ (Rev.B) The reverb effect is injected into to the sound path in an odd way. If you decrease the input volume while turning the master volume up that's fine, you can get the reverb more than needed. However, if you want to get gain and grid by turning the volume up, then the reverb gets subtle and subtle as you increase the input volume which makes the reverb useless. I was wondering do you have a suggetion to fix it? I heard that this problem was fixed in BJ when fender switched to the cream board so that the owners of BJ II and III should not have been frustrated with the reverb issue.

I would love to see your evaluation/thought process on the newer Hot Rod Blues Jr. IV w/the black pc board circuit & schematics.

Awesome, please do the same with pro Jr, maybe with indications like Master + Volume, Presence, FAT.

A quick question. I want to half the output for smaller venues. Would it be as simple as disconnecting pin 2 on one of the EL 84s and grounding to earth so it's not floating? And leaving, depending on which valve is used, R20 or R23 floating. I'd probably put SPDT switch to bring it back to full power. Love the video especially your children in the background

I had an Epi valve Jr, V1. Bill M was so helpful and wanted to help me out but I'd already sent it out to be worked on by some doosh in Texas. So BillM, helped me without any money, wanted to just help me out. That's rare, buy his stuff kids

Awesome breakdown of the circuit. What are your thoughts about changing the bridge rectifier from solid state to tube to introduce the sag in voltage that tube rectifiers are known for?

O just one more thing I know it could be a matter of reliability versus sound but what output tubes do you prefer to use on these amps? Thanks c];-)

Can you also do the same analysis on the Blues Jr III. Seems there are changes to the circuit and I don't want to make changes that would damage the BJ III circuitry.

The reason the schematics for Blues Juniors as well as many other amp's show the V1B before V1A is because it makes for shorter, more direct wiring from the input to the grid of V1B. Then the wiring from V1B into V1A also continues logically in a more direct downstream direction. You will also see the same thing with V2B before V2A, etc... I suppose if the nomenclature on the schematic bothered you that much, you could rotate all your preamp tubes 180 degrees in the chassis but this could compromise better wiring practices for the heater filaments, cathode and anode.

I read somewhere you should substitute C4 using a 250uf electrolytic... or do you think the suggested .047 is better?

Love the baby crying !!!!!!

Hello Kley De Jong, I suppose the fat switch could be used to lift the tone stack? Also, is this the first version of BJ after US production?

As far as I know the 1M volume control after first triode is a LINEAR control. The 130K from the wiper to ground re-shapes the control curve of this pot. Fender have chosen to do this to produce a custom volume control curve rather than use a standard curve log pot.

At 12 minutes into your video you mention putting the ground at [R29] from the mid pot on a switch. Can that still be done if the cathode follower mod has already been done to the amp?

Can you do that for the Hot Rod Deluxe 3?

R5 130K is a grid leak resistor for V1A. If you clip it out, the Volume pot will have a DC current thru it and will become noisy.

ur a genius u know what ur talking about the diagram

Hi Klay! A week ago my amp worked normal, but now the "FAT switch" has stopped working. It is as if it was always on. Looking for information, I understood how it works, but I still can't find the fault. Could it be that Q1 is failing? Thank you!

Question...On a new Blues Jr. 111 can you just clip the wire on C2 to tame the Treble? Thanks!

Need to make a larger curser and or different color . Informative though . Thanks

if you were to disconnect the Mid pot, the next stage would have no grid leak. The ground of the pot is the grid leak.Am I wrong? Couldn't that mess up the bias of the next stage?

Nice walk-through, but went straight over my head due my utter lack of knowledge in electronics. I'm assuming this demonstration pertains to the later creme board generation/s. I have a 1997 green board BJ I'm trying to troubleshoot, which according to my preliminary research and comparison of respective schematics, is somewhat different from the creme board version. Too bad I live in a backwards, underdeveloped part of the world where I have no access to qualified amp techs to take the amp to, which means if I don't figure out how to fix the issue myself, a perfectly good amp is gonna end-up in a junk pile.

Are you still modding blues juniors? I just got one and am looking for someone to improve the overall quality.

would you please be so kind as to send me a copy of the blues junior schematic, can´t find it anywhere, thnk you so much

Which Blues Junior are showing???

I would think folks who play the blues would not want to have a large bass response cause you the step-on frequencies used. by the bass and drums It's kind of true for other types of music as well Most folks I know who want to cut through and be heard lower the bass! So perhaps the designers had it right and what folks are looking for is a marshall or some other amp with the more bottom end?

Bic Lighter

The numbers on the components do not match with blonde board...

You said change the bass pot to 1k do you literally mean 1k or did you mean 100k

"Infamous" is for things or people who do horrible things that make them famous in the worst possible way. You don't want to be infamous. Charles Manson was infamous, so was Jim Jones, and Lizzie Borden. The word you are looking for is "legendary".

to much gain? wth is that? is that even a thing?