Fender Blues Jr - Everything You Need To Know About Reliability And Tone Voicing!

Join me in this highly detailed step-by-step implementation of Pro Amp Solutions Fender Blues Jr modifications for road worthy reliability and greatly improved voicing. Watch this complete video from end-to-end and be enlightened. Eye candy and tone that will bring a smile. The results sound outstanding. Love Your Tone!
Following are the reliability and tone voicing stages and associated component details for the cream board...
I am happy to make a custom kit of the Pro Amp Solutions Blues Jr reliability and tone voicing components. Reach out to me at: [e-mail]
RELIABILITY:
Stage 1: Filter Cap Replacement & Adjustable Bias - ESSENTIAL!
C25: 47uF 450V F&T Axial Electrolytic (100uF for Stage 1 Tone Voicing)
C26, C27, C28: 22uF F&T 500V Axial Electrolytic
C30, C32: 470uF 50V Nichicon Radial Electrolytic 5mm Lead Spacing
C31, C34: 220uF 25V Nichicon Radial Electrolytic 5mm Lead Spacing (NOTE OF CAUTION - C34 POLARITY IS INCORRECTLY MARKED ON THIS VERSION OF THE CREAM BOARD, NEGATIVE SHOULD BE TOWARDS THE BOTTOM OF THE AMP - This was the root cause of the blown top of this cap when the amp came into Pro Amp Solutions - it was installed backwards, I replaced the 15V Zener and the 220uF with the correct polarity and that cleared up the problem.
R52: 50K 10-Turn Potentiometer
Stage 2: Speaker Cable & Input Jack
Jack: Switchcraft Type 12A
Speaker Cable: Neutrik or Amphenol Right Angle Plug & 18AWG Stranded Wire Soldered To Speaker
Stage 3: Replacement Tube PCB
There are multiple options available, here is one…
borishelectronics.com/product...
TONE VOICING:
Stage 1: Reservoir Cap & Speaker Change
C25: 100uF 450V F&T Axial Electrolytic
Speaker: Your Preference, My Favorite: Scumback BM75-8-25W
Stage 2: Tone Stack, Coupling Caps, Bypass Cap & Plate Resistors
C6: .1uF 400V Polypropylene Film
C3: 250pF 500V Silver Mica (Not A Value Change, A Better Cap For The Application)
R11: 82K 1/2W Metal Film
C2, C8: .022uF 400V Polypropylene Film
C1: 1uF 25V MOD Axial Electrolytic
R3, R8, R16, R30: 100K 1W Metal Film (Plate Resistor Noise Reduction)
R28: 91K 1W Metal Film (Plate Resistor Noise Reduction)
R29: 9.1K 1W Metal Film (Plate Resistor Noise Reduction)
Stage 3: Reverb Tank, Reverb OpAmp, Reverb Return Gain, Remove Treble Bleed
C23: Remove and Omit (.0033)
R44: 120K 1/2W Metal Film (180K if you want to swim in Reverb)
U1: NJM4556 Hi Current Dual OpAmp
Reverb Tank: MOD 8EB2C1B (Note Mounting Application)
TUBE VOICING RECOMMENDATIONS:
Power Tubes: TAD or Tung-Sol EL84/6BQ5
Phase Inverter: Tung-Sol 12AX7
1st Preamp Tube: Mullard CV4004/12AX7
2nd Preamp Tube: Mullard ECC83/12AX7
SUBJECT MATTER TIME SEGMENTS:
0:00 Welcome, Let’s Get Started!
0:10 Reliability Concerns & Tone Voicing
2:14 Before Changes Audio Test
3:35 Initial Inspection: Amp Not Grounded, Leaking Caps
5:08 Reliability Stage 1: Reservoir Cap & Adjustable Bias
6:48 If Your PCB Is Not Cooked Yet, It Will Be!
7:18 Reliability Stage 1 Is Essential!
7:41 Reliability Stage 2: Speaker Cable & Input Jack
8:50 Reliability Stage 3: Replace Tube PCB
10:03 Tone Voicing Stage 1: Reservoir Cap & Speaker Change
11:12 Tone Voicing Stage 2: Tone Stack, Coupling Caps, Bypass Cap, Plate Resistors
12:59 Tone Voicing Stagea 3: Reverb Tank, Reverb OpAmp, Reverb Return Gain
14:39 Tone Voicing With Tubes
14:47 Tone Voicing Overview
16:12 Good Time For Tone Voicing Stage 2 & 3!
17:58 Component Removal Technique
18:14 Look At The Electrolyte Leakage
18:51 Learnings, Techniques & Overview Of Removed Components Part 1
22:03 Turns Out C34 Was Installed Backwards And The 15V Zener Diode Was Failing
22:16 Learnings, Techniques & Overview Of Removed Components Part 2
26:00 Soldering Technique
28:09 Stage 1 Component Population Complete
29:07 Stage 2 Component Population Complete
30:28 Stage 3 Component Population Complete
31:22 Take Care With Input Jack & Potentiometer
33:03 Completed Component Installation Walk Through
34:36 Care And Technique Of Main Board Removal
36:02 Stage 1 Component Overview, Stage 1 Is Essential!
36:28: Stage 2 Component Overview
36:57 Changing Plate Resistors To 1W Metal Film Reduces Noise
37:22 Stage 3 Component Overview
38:19 How To Bias Explained
40:30 Tone Voicing With Tubes Example
41:26 Stage 3 Reverb Tank Installation Technique
42:43 Completed Work Audio Test - Stay Tuned There Is More…
43:52 Completed Work - FAT Audio Test
44:46 Contact Information: [e-mail]
Thank You For Watching My Channel,
John

[@bbmade]

Glad I found your channel! I just got done with about 12 Blues Junior resto’s. I did most of what you describe but great insights, great detail and some additional info that is fantastic. Thank you!

[@proampsolutions]

Thanks for your feedback, much appreciated!

[@thatampguy]

The bipolar power supplies are always suspect in the Hotrod lineup. Great video.

[@mackenziegreen1215]

wow, great video, ive been looking into this amp as a main amp, as im downsizing, and im also an apprenticing amp tech and looking for a challenge. lots of good info here. thank you for doing what you do. cheers!

[@noslen954]

outstanding job!!!👍👌💯

[@michaelweinman9051]

Awesome!! love this! wish I had one! ha ha From mtw in L.,A.

[@proampsolutions]

Thanks 👍

[@philchapman1463]

I like the original sound, it seems more 3 dimensional and ambient and chimey, like I expect a Blues Jr to be : )

[@BeauregardHall]

Great video - the weakest part is the sound tests... sound like they were recorded with a soup can and a string. But that's okay. Great great job.

[@mikebarnard2689]

How sad these popular amps seem doomed by design to fail. Really, Fender should have recalled them and sorted the overheating power tubes at the very least. These amps are not cheap... in the UK they retail well over £600 and I’m sure the repair work you have done is equivalent to a minimum 1/3rd of the cost of the amp. Throw in a speaker change and you are into 50% of new cost easily. I’d love to hear amp techs recommendations for affordable small tube combos that have been designed and built properly. I bet it would be a short list !

[@ediek8048]

WOW! That's incredible detail. I have a new Blues Jr. IV and it sounds fine for my purposes. It has a black PC board, which I have never seen on any KZbin feature. There is at least one difference I can see on the board: it does not have the bias resistor pair (I think that is the R51 R52 pair) that techs like yourself will modify. There is just one resistor in that location. I don't know what that means for the problem of overheating, but the amp sure runs hot. There may be other differences, but I wouldn't know enough to tell. Thanks for your video. Really appreciate it. Fascinating.

[@proampsolutions]

Thanks for your feedback. The black PC board Blues Jr IV is cathode biased, not fixed biased like the cream pcb. I've worked on a couple of these and even though they are cathode biased, they still seem to run too hot, but much improved. The last one I saw was right at 100% which does not leave any room for line voltage fluctuations. I like to see cathode biased amps run between 90-95% idle dissipation. If you are concerned, I recommend taking it to a qualified service tech. If it is too hot, the value of the cathode resistor can be changed to dial the idle dissipation it in where it needs to be.

[@nellayema2455]

I have a IV as well. It's a good sounding amp. My only wish it that it had an effects loop, but many Fender models don't. I have other amps that do, so it's not really a big deal to me.

[@GooberNumber9]

@@proampsolutions Thank you!! I just confirmed I have a black board BJ IV and I was curious about the cathode bias.

[@nocturne-music-jpn]

Thank you for stimulating video. What gear do you use in opening jingle?

[@mikehoehn1475]

What's the cost of all 3 mods ?

[@nicksregor4208]

I'm so interested in absolutely everything going on so far in this video, but I'm at the part where the ceramic disk cap is being described as inferior to the silver mica, and I'm so curious about the legit reasons for this... like, the cap is a Z5U or something susceptible to temp, but like... what beyond that... scientifically speaking??

[@tombryan1]

That blue wire should be above the brown wire to help it clear the power section ribbon cable and reduce hum from capacitance coupling, just from my experience

[@JillandKevin]

I have a couple of questions. First, I'm guessing that the power tubes run hotter as the amp is cranked up? So if someone used it in a low volume situation (small venues, Master all the way up & low gain, no cranked distortion), would it last longer) Second, would a cooling fan help alleviate tho problems? Thanks! Kevin

[@BCEpedals]

No, the bias needs to be fixed regardless of the volume you play. And a fan won’t help enough. These get hot enough to melt PCB traces.

[@JillandKevin]

@@BCEpedals So, the second half of my question: I'm guessing that it gets hot because it's being pushed hard. I've been playing around 4 gigs a month with BJ's ever since they hit the market in '95, and the same one since the Cream Board came out in 2002, and have had no problems with heat at all. There is no visual evidence of overheating. The only explanation I can think of is, I don't try to get it loud or to breakup, so maybe??? I've used it in (early Chicago style) Blues bands (before they got loud and distorted), A nine piece Western Swing Band for ten years, small Jazz bands, Swing Bands, and Country Bands, but never needed to crank it up enough to distort it.

[@user-jz4gy2vk4c]

What amp would you recommend for around 1500 or less,thanks.

[@JillandKevin]

Question. How does a BF Princeton Reverb RI compare in reliability? Will it have all these problems?

[@BCEpedals]

The blues junior is probably the worst of them all, but the other reissues would still benefit from a recap, different speaker, speaker jack, tightening of loose hardware, tone adjustments, and better input jacks.

[@gnatiu]

I never had any Fender gear that did NOT needed extra pimping. That is why I don't buy anything of this brand anymore. The damage on the board is something I am aware of. The first series - made in USA - hums like sh.t when you turn the reverb on. What I find interesting is that people spend a lot of money for US equipment and have to modify it afterwards - in a way it should be already when you buy the product. And no one seems to find this awkward. Only US made weapons seem to do their job properly. I swapped my Blues de Luxe Reissue and my above mentioned 1995 bought BJ with Japanese stuff - great sound and reliability under ALL circumstances since then. Fender to me is at the very most "The brand that creates urban legends." All the hue and cry about Fender - and especially Gibson - is just hilarious.

[@Jesuswinsbirdofmichigan]

Sept.-1-2023, ✝️

[@MrAletube]

problem is that speaker is the worst of all,you really need to get a decent one to hear the real sound of the amp circuit,no shortcut here

[@tobywestfall2970]

It's a disposable amp. Just throw it out and get a new one

[@rikkitikkitavi3118]

Just looking at those PCB's , I see that Fender is outright RIPPING-OFF thier buyers. Wake up people!

[@Nick-ej3qe]

They all do. Every amp company tries to get away with as much as possible to save a few bucks. Long gone are the days of companies over engineering products for the customers sake.

[@harveythompson1756]

Sounds worse after all that messing !!

[@grif900]

It still sounds utterly horrible. All you need to do to make it sound a little more like a Princeton is to cut the mid pot way back.

[@yaniv-nos-tubes]

one of the worst amps on earth only a vintage mullard at v1 can save the tone