Series III Blues Junior: What’s Different?

Back on September 1, 2010, when the Blues Junior Series III was introduced, I went to Guitar Center and bought the first one they’d been shipped. I promptly took it home and had in pieces on my bench. Fender claims a bunch of improvements, specifically:

  • Black panel with white letters, reversed so it’s right-side up when the amp is behind you
  • Screw-on knobs
  • Rattle-reducing retainer for EL84 output tubes
  • New “Lightning Bolt” speaker
  • “Sparkle” mod
  • Dog-bone rubber handle.

Black/reversed panel? Don’t care.

The screw-on knobs are a slight improvement, but the cheesy pots are still soldered to the board. The pots and shafts are protected by the same bushings as found on some old Bronco amps and other low-end designs from the early 1990s.

The bushing fits the shaft and the panel hole perfectly. It stabilizes aftermarket knobs and protects the pot.

It’s no better than the old knob on the left, but it makes it worlds easier for Fender and owners to use whatever color knobs they want.

The rattle-reducing retainer?

Two rubber grommets cushion the tubes, may help damp vibration.

They stuck a pair of rubber bushings into the half-inch holes at the top of the retainer. I tried this some years back; didn’t find a compelling reason to make it standard. It probably helps a little.

The new rubber handle is more comfortable in your hand and comes up higher, so your knuckles don’t scrape on the Tolex.

Those are mostly cosmetic changes. I don’t give a hoot about cosmetics, just tone.

Sparkle or ice pick?

The “sparkle mod” is the big change. All they did was remove capacitor C10, replacing it with a jumper, and remove capacitor C9 entirely. There’s some history to C10, going all the way back to the original green board Blues Junior. The green board reverb was positioned after the master volume, which turned out to be a bad idea–any hum or noise in the reverb went into the output stage full blast. The input and output were separated by a resistor and a capacitor.

When Fender revised the reverb circuit and switched to the cream board they moved the reverb pickup and insertion points before the master volume. It improved the performance because the reverb changes proportionally with everything else when you change the master volume. Reverb hum and noise get relegated to the noise floor–a big improvement. They used an existing 470K resistor to separate the input and output, but left the resistor and capacitor from the green board in place after the master volume to keep the overall tone the same. The capacitor became C10 on the cream board.

The series III is the same cream board, but Fender realized that the  capacitor was slightly limiting both the amount of signal and the frequency range going into the output stage, so they replaced it with a jumper wire. Actually, this mod has been floating around for a while. There’s a mention of it somewhere in the comments on one of these pages and it seems to be popular with some of my European customers.

C9 is a voicing cap. It knocks off a bunch of high frequencies by bleeding them to ground. In the early days of green board mods, I used to make it switchable, between the stock 1500pF and 300pF. The 300pF let many more highs through and gave the amp noticeably more “sizzle.” I never thought that the cream board needed this mod, since it was brighter overall. Fender evidently thought differently, and did away with the cap completely. So if your Series III has too much zing and sizzle, you could always tone it down by adding anywhere from 300 to the original 1500pF.

How does it sound? Sparkly! Kind of Twin-ish, brighter. If you’ve always thought that the cream board Blues Junior was too bright, you’re going to hate the Series III. There’s more snap, more crisp response than the previous cream board. Most people will agree that the amp sounds more Fender-y. Treble settings over 7 or 8 with single-coils can be painful, however. I’d bet, though, that humbucker players who found the BJr muddy will appreciate the brightness.

To sparkle or not to sparkle

But it’s still the cream board at heart. The coupling capacitors are still wimpy and the tone stack is still lame. Fender also went to lower-grade coupling caps in the preamp, although there is probably no audible effect. Of the two capacitor mods, replacing C10 with a jumper adds a small, just-audible roundness and bottom-end warmth to the tone. With the modded Billm tone stack, replacing it isn’t really necessary because the amp adds prodigious amounts of bass and expands the range of mids from none (less than stock) to more than stock. But jumpering C10 doesn’t hurt a thing. I’d do it to any cream board Blues Junior.

Removing or clipping C9 is another matter altogether. It’s the “sparkle” in the sparkle mod. With single coils, I just don’t like the sound of the amp without some amount of high treble roll-off.

The Series III benefits from the same mods as the cream board. Indeed, the enhanced bass from the modified tone stack balances out the amp’s brightness. I’m tempted to add a “taming” cap for C9.

What about that new Lightning Bolt speaker? Overall, I’d say it’s an improvement. The fizzy highs of the old gold label Special Design are gone, but the speaker is plenty bright. The bass is tight, a bit better defined than the gold label. It’s well balanced top to bottom, but the bottom isn’t very deep. I didn’t have an Eminence Red White and Blues on hand to compare, but the Lightning Bolt sounds rather similar. That isn’t a good thing for the Blues Junior. I A/B’d it against the gold label and against my trusty Swamp Thang. The Swamp Thang is the speaker the Series III deserves: full, round bass and moderate highs.

For my part, I’m glad that all of my mods still work for the Series III.

You’ll have to decide for yourself whether you want to jumper C10 on your cream board BJr. If it’s the only mod you do, I don’t think you’ll hear much difference. In conjunction with the basic mods, it adds a bit of useful roundness and fullness to the amp.

Other Changes:

The first power supply resistor is now up in the air for ventilation (and not charring the board if it burns), along with the second power supply resistor. Both are supported by little fiberglass tubes or insulation over the leads.

Hum balance resistors are larger, the 2.2K is (finally!) elevated.

The hum balance resistors on the filament line are now larger, 2- or 3-watt resistors. They no longer fit flush on the board, so they’re angled up in the air, with fiberglass sleeves over the exposed leads. Even though the circuit board now bears a 2010 copyright date, I haven’t found any other changes yet.

The pilot light is still an LED, but now the lens is a faceted red jewel instead of the little lens. The jewel is not interchangeable.  It and the bezel are one piece. Although it’s held to the chassis by a nut, there are no commercially available jewels in other colors that fit. Even if you were to change it, you’d have to change the color of the LED too. Red shows up as a dim purple through a blue jewel, for instance.

The new LED "flower" fits inside a red jewel lens.


  1. Allan w. says:

    I was wondering about the new version…..
    ….. thanks for the info.


  2. Steven says:

    Hi Bill,

    Any immediate improvements you see from the changes that should be done on a cream board?

    Like: …the hum balance resistors on the filament line are now larger, 2- or 3-watt resistors…or
    …The first power supply resistor is now up in the air for ventilation (and not charring the board if it burns), along with the second power supply resistor. Both are supported by little fiberglass tubes or insulation over the leads.

    Are these significant changes or just small good ones?

    Thanks, Steven

    • bill says:

      I have never seen the hum balance resistors fail. I don’t know why they made them larger. The first resistor burns if the screen grid shorts in the EL84. Putting it up in the air prevents damage to the board.

  3. Catscratch says:

    Glad you’re still in business Bill.

  4. Joel CHAMPETIER says:

    the 2.2K is (finally!) elevated

    OK, i understand now because my BJR burned


  5. David G says:


    Just bought your cream board mods and the TO20 transformer for my BJR, looking forward to installing them.

    More on topic of this new series III, did Fender address the output tube bias settings or are they still running hot?

    I really like the bias adjustment in the HRD, where you have a testpoint to measure current. It would seem a simple circuit to build for a BJR for biasing. What do you think?



    • bill says:

      The output tube bias is the same — still hot. There is no convenient place to mount a 1 ohm resistor on the cream board, unfortunately, so a bias probe or using the transformer shunt method is best.

      • David G says:


        I was looking at the Amp-Head website for a bias probe setup. I am looking for something quality and I see on a thread on the Gear Page where people have been happy with Amp-Head. Do you have a preference on these?

        • bill says:

          I don’t use a bias probe. I measure voltage drop at the output transformer. It’s more dangerous (working with high voltage), but doesn’t require any additional equipment or tube unplugging/plugging.

          • David G says:

            >I measure voltage drop at the output transformer.

            So, what sort of voltage drop do you look for? 🙂

          • bill says:

            The measurements for transformer-shunt biasing vary with the output transformer. I provide instructions with the basic mods kit.

  6. Steven says:

    Is elevating the R47, R48, the first and second power supply resistors a good mod and easy for an amp tech to perform? I mean to elevate them like Fender has done? Thanks, Steven

    • bill says:

      R48 is elevated on all rev C cream boards and it continues on Series III boards. You’d have to replace R47 with a new resistor so you’d have longer leads to elevate it. Elevating R47 makes much more sense than R48–I’ve never seen R48 burn, but have repaired many boards burnt under R47.

  7. Steven says:

    Fender’s youtube channel now has some demos of the new versions

  8. Steven says:

    Would you say that the Blues Jr III sparkle mod is similar to your prescence control mod or are they quite different?

    I’m getting almost all your mods, and just trying to decide if I should also do the sparkle mod or not.
    I think the combination of the prescence control + treble would get things plenty sparkly but wanted to ask your opinion.

    I think these are the available options:
    1. Replace C10 with jumper and remove C9 entirely – sparkle mod
    2. Replace C10 with jumper and leave C9 cap as is
    3. Replace C10 with jumper and change C9 cap to say 700pF
    4. Replace C10 with jumper and put in 3 way switch to set C9 at 0pf, 300pf, 1500pf : )

    Thanks again,

  9. Emmanuel G. says:

    Merci Bill !

  10. Hi Bill,
    Just traded in my, lets call it “Blues Jr II”, since it had a 2010 cream board, and was nearly identical to “BJR III” with elevated hum balance resistors and power supply resistors. I do, however, like the new cosmetic looks.

    The new Fender manual suggests matching the color and number rating of the installed Groove Tube EL84’s, to maintain optimum performance. I also noticed with some consternation that Groove Tube is a wholly owned subsidiary of FMIC, which is Fender Musical Instruments Corporation.

    My question(s) are this, since I traded in my BJR II for a III. Will you provide bias control for the BJR III, as I would prefer to switch to JJ Tubes and further optimize my amp? You had also stated with the previous models, that the OT would support 4 ohm, as well as 8 ohm speaker load. Did you mean the stock OT, or your beefier OT?

    Since the new speaker isn’t broken in yet, I cannot comment, but since I primarily play Blues, I took your previous advice and ordered an Eminence GB128 anyway.

    My last question is this. Why don’t you also offer a point to point hard wire mod, and do away with the PCB entirely, for those of us who don’t like to work on this type of bs set-up. I like to build guitars, not modify circuit boards. At least I can get my hands into an old eyelet card and place quality components any place I wish. I think this could be a great little amp, even utilizing the same chassis and cabinet. IMHO.

    Thanks for taking the time to listen, I’ll be ordering parts soon. Don’t want to void the warranty just yet.

    Steve A.

  11. John says:

    Well, it’s bright! I did both sparkle mods on my cream board junior. The result is definitely brighter. With my Eastman dual humbucker archtop, I like it a lot. With my G&L legacy (strat), it’s perhaps a little too bright, although you get used to it. It also passes through more finger noise and rf interference. I think I’ll put a smaller cap back in C9 so I can lose some of that.

    • bill says:

      I’m thinking that the “sparkle” version of the Blues Junior doesn’t need a presence control, but needs a variable cap on C9 to roll off the high-high end. I hope to test that later, and maybe it’ll become the new Series III presence control.

      • John says:

        Sounds like a great idea. Rotary make-before-break selector switch might be nice. I usually have the presence all the way down as I play clean most of the time.

        I put a 470pF 1kV cap in C9 and it did the trick for me. Took the edge off the shrillness and brought the chime back. A smaller cap may work too. Also found that rolling the Legacy guitar volume back to 8 or 9 cuts the rfi a lot with the loss of just a little high treble. YMMV as that’s going to be a function of pickups, cables, pots, etc.

        Another thought is jumpering C11 and leaving C10 in the circuit, although the calculations say that it shouldn’t make much difference. Or jumper C11 and put one of your orange coupling caps in C10…

        • bill says:

          I think you’d want to leave C11 alone so the phase inverter works properly. The 10:1 ratio on the grids is part of the balancing act, although you occasionally see larger input caps.

          I would use a pot and a larger cap on C9, not a switch. Like a tone control, but for the highest frequency band.

  12. Adam says:

    I don’t think you’ve given this a fair shake. Even though it isn’t a vast improvement on paper, tonally it really has improved quite a bit. I’ve considered buying one for years now and this series, by far, is the best Blues Jr yet. I love the chimey sparkle of Fender amps, and until now the Blues Jr (without your mods) hadn’t been a very Fender-sounding amp. Now it fits into that catagory and less into the nasty nasally area it had fit into previously. I’m curious to see how much better you can make it. However, the Blues Jr III sounds great out of the box.

    • bill says:

      Fair shake? How is this not a fair shake?

      How does it sound? Sparkly! Kind of Twin-ish, brighter. If you’ve always thought that the cream board Blues Junior was too bright, you’re going to hate the Series III. There’s more snap, more crisp response than the previous cream board. Most people will agree that the amp sounds more Fender-y. Treble settings over 7 or 8 with single-coils can be painful, however. I’d bet, though, that humbucker players who found the BJr muddy will appreciate the brightness.

      But it’s still the cream board at heart. The coupling capacitors are still wimpy and the tone stack is still lame.

      I’ve done the basic mods to mine and it’s vastly improved. But I get email every day from players who find the stock Blues Junior too bright. I’d say that the Series III is unusable in stock form for jazz players, people who like that size, a 12-inch speaker, and tubey warmth. It’s impossible to get that round, resonant tone out of the stock BJr III. After the the basic mods, it’s much more versatile, but it’s still very bright and zingy. After a couple of days of experimentation, I think it needs a top octave control–a treble control above the normal treble range, so you can knock off the high-highs or dial in the full “sparkle mod” amount. I’ve built one of these already, but it’s going to take some special-order components to make it work as a kit.

      • Drake Remore says:


        My questions are in good humour, please be advised. 🙂

        Why do you feel the need to modify amps? There are thousands of Fender BJ III’s rolling out there there. I’m sure you get complaints from maybe a few hundred people tops, but there will always be owners who complain no matter what they have, how much they paid, or who made it.

        Are there any amps that you DONT feel need modification or do you generally feel compelled that all amps are ailing in some way?

        Why doesn’t Fender just put these “vastly improved” modifications you make into their amps if they are so much better than what they’ve done? Do you think they are trying to create products people feel the need to modify?

        I enjoyed reading your analysis of the amp and it’s obvious that you have a passion for what you do. I’m just sort of eye rolling about your need to tinker with things to “improve” them. Will you ever be satisfied? Perhaps I’m missing the point, which I’ll gladly accept.

        • bill says:

          The point is this: The modded Blues Juniors sound much better than the unmodded amps. If you ever get the chance to hear the difference, you’ll get it. Fender has its reasons for building the amp the way they do. I’m cool with that and they’re cool with (and familiar with) my mods.

          • Andrew Mast says:

            Yea, I JUST bought a BJ III and I understand Drake’s POV but at the same time (most) people wouldn’t be modding if there wasn’t an advantage gained.

            I’m surprised to see people doing that since it renders the warranty void. Here’s my amateur review and a medley of riffs recorded using the new Blues Jr. III on my telecaster. It’s my first Fender amp so I have nothing in the Fender realm to compare it to.

          • bill says:

            Your demo recording is terrific. You get a lot of nice tones out of the amp. I wish you could play my modded Series III side by side to hear the improvement in tone and greater range of tones available.

        • Mystic38 says:


          An extension of your question would be “why change pickups” or “why change guitar strings”.. on a new guitar…and when put like that doesnt it sound absurd?

      • genesiospinola says:

        Hi Bill! I bought the Blues Jr III and i’d like to know if is possible to change to the previous cream board, because a didn’t like the sound (snap and more crisp). If possible…what i have to do?? Cheers!!!!!!!!!

        • bill says:

          If it’s too bright for you, put a 1500pF 1KV ceramic cap in C9. That will restore the older cream board sound. By the end of January, I will be offering a “de-sparkle” control like the presence control, to make the brightness variable.

          • Bluz says:

            Hey, I bought a BJIII I want to mod (I liked the review presented by Stevie Snacks) and my questions are: 1. Does the kits include this “de-sparkle”? 2. I have 2 250pf silver mica caps left from a mod of a Crate v18-212, what’s your opinion of using the 250pf silver mica in C9? I noticed in other replies you prefer using 330pf. Thanks!!

          • bill says:

            I haven’t started building the de-sparkle controls yet. My plan is to put them on the site, along with a recording of how it differs from the presence control.

  13. Scott says:

    “Black/reversed panel? Don’t care.”
    lol. That is so funny, sure it’s a good idea but I’ve gotten so used to it being upside down that it doesn’t even matter. Thanks bill for focusing on the sound, That’s why your mods turned my BJr into my favorite amp. It will be interesting to see where the “sparkle mod” leads you. Good luck.

  14. Markus says:

    Hi Bill,

    so no one read your modpage at Fenders’ or what do you think?
    Most of your tone improvements are not that expensive and
    as you said, the way they mount pots and 1/4″ input was already changed in other newer amps,
    so that there was no improvement in pots and 1/4″ inputs is very very sad.

    Anyway, you are still in business. But to say it in a brighter way,
    it would have been too bad if they took all your ideas and left you with nothing than a good sounding amp.

  15. Rick Mantell says:

    Hi Bill, for anyone interested – the rubber grommets on the tube holder in the BJr III are the same size as the grommets used in a home brew airlock kit. A couple of bucks at the local brew or hardware shop. Thanks Rick

    • BillEvans1956 says:

      Hey Rick! Just the sort of information I was after. Thanks. After the power tubes in my BJr II fractured at the base, I didn’t replace the retaining plate when I replaced the tubes. The tubes seem to be seated fine without it and I don’t notice any tube rattle. But, I’ll look out for those rubber grommets just the same. Thanks. Bill

  16. Andrew says:

    hey bill, so my question is, compared to the old blues jr. which one is going to get better growl when the volume is cranked for rhythm tones? (lets say for example when the master is at like 3 o clock and the reg volume is at like 1 o clock)

    and when i say growl, i mean balanced growl (not too thin not too thick) like a good p-90 does. a nice “brangggg” sound.

    • bill says:

      The growl is pretty much unaffected. Jumpering C10 makes the tone a tiny bit beefier (really, it’s barely audible if you put it on a switch and flip back and forth) and removing C9 makes it brighter. Neither really helps that edge-of-breakup tone. The extra highs can be helpful when you need to cut through the mix.

  17. _Dutch says:

    Hi Bill and all. I was wondering if anyone could help me. I have a green board BJr and I really want to try the Sparkle Mod. On mine, C10 is a filter cap for the power supply and C9 is not even shown on the layout I got from the Fender website. The file I downloaded shows 2 different layouts and 2 schematics. I’m having a little trouble reconciling the two as they are unreadable even with a magnifying glass. Can anyone tell me which cap to remove and which to jumper on the green board?

    • bill says:

      The capacitor that’s equivalent to cream board C10 is green board C19, but it’s part of the circuit that separates the reverb send from reverb receive. On a stock green board Blues Junior you’ll screw up the reverb if you jumper it. If you do the reverb mod, you can jumper it.

      The voicing cap (C9 on the cream board) is C35 on the green board. Feel free to remove it or replace it with a smaller value. I like 330pF.

      • _Dutch says:

        Thank you very much for your help Bill. You offer a great service to all of us with your free advice. I hope to pay it forward first chance I get.

        • _Dutch says:

          I removed C35 and also did the TwinStack mod on a friend’s BJr. I say the enhanced high end is definitely a plus for getting some decent rock tones out of the amp. It seemed to make it possible to push it without having the low end get out of control and ruin the note definition. I liked it so much that I’ve ordered a used BJr for myself and I’ll be ordering a few of your mod kits soon. Thanks again Bill!

  18. John says:

    Bill, the cream board schematic on the Fender website is revision A. There is no fuse in the heater circuit. The heater balance resistors are 1/2w 47ohm FP, which I have read means “flameproof”. I have also read that these were designed to melt and go open circuit in case of an HT-heater short. Why this would help and how it would protect the PT is unclear to me.

    The schematic that came with my BJr is a Rev. C. The resistors are the same but there is now a 5A fuse between the PT and the resistors, presumably to protect the PT.

    Does the MkIII have the fuse? Are the resistors still 47 ohm? Any idea what the logic is behind the power rating increase? Perhaps they are designed to last long enough for the power fuse to blow?

    • bill says:

      The Series III has the fuse, too. I believe it was added for Euro rules–gotta have a fuse on any line carrying more than a certain amount of current. I think the resistors were upgraded for the same reason. Anything in a potentially high-current application needs to be flameproof these days. The fuse and FP resistors are there in case of a filament short.

  19. Chris says:

    Hi Bill,

    I have a very new BJ3, two weeks old, and today one of the valves went crazy, so I went and asked the shop for replacements. The old ones were the Groove whatever they put in at the factory. They gave me some JJs, the same model number, and I unscrewed the back and swapped the valves. No problem. But when I turned the amp back on, there was an almighty humming. All the volumes were down. I played the guitar through it, it works fine, but that hum won’t go away. I switched the valves around in their sockets – still humming. You’ve talked about this for older models – is this still a problem you know about?

  20. Josh Bradshaw says:

    About the hum balance resistors – I had a junior that hummed like the dickens and I took it apart probably 15 times trying to diagnose the source of the hum. Finally, I took those two resistors out and measured them – they were wildly out of spec! So I know of at least one pair that went bad.

  21. DomFuriani says:

    Hey, i just got the Bjr III. and i play alot of jazz for the most part. and i wanted to do the tone stack mod and stuff to clean up some dense chords. That cap you mentioned was sounded interesting also could i get a little more info.

    • bill says:

      Everything you need to know is on the order page. The basic mods kit and TwinStack do wonders for the Series III. I’ll be offering a brightness control for the III soon to help tone it down if it’s still too bright.

  22. Eric Bernhardt says:

    Oh man my III will be here next week! This site has gotten me very excited. I want to play the stock amp for a while to get to know it then gradually add the mods and document my journey. I like a lot of mids so maybe the sparkle will be too much for me so I’ll keep an eye out for upcoming de-sparkle mods just in case.

    I chose to get this amp because:
    1. I played one and loved it.
    2. It’s priced so well.
    3. This website is so informative and passionate so I feel like I’ll always have support.
    4. I love to tinker and modify my equipment so it’s a great way to evolve my hobby.

    Thanks Bill!

  23. Bob A says:

    This review was great. I just bought my first Blues Jr.(a III of course), which I consider my first real amp. I look forward to adding your mods over time and am very happy to have this resource for us amp owners to use.

  24. Edson Rodrigues says:

    Does anyone know where I can get those tube-ruber-dampers for the EL84’s ?


    • bill says:

      They’re just half-inch rubber grommets. They, or a metric equivalent, should be available from industrial supply companies.

    • BillEvans1956 says:

      Hey Edson. I was thinking about buying some rubber gromments for the tube retaining plate in my BJr II, but have removed it altogether at the moment without any ill-effect on the EL84 tubes I have in there right now. The original Sovteks both cracked at the base. I figure maybe due to excessive rattle. I replaced them with a matched pair of Harma brand EL84. Works fine now. Bill

  25. Eric Bernhardt says:

    I recently purchased a III (my first tube amp actually). I hope you can help me on this issue, since I know you don’t do pedals and you’ll probably tell me to do the basic mods, but here it goes:
    My tube screamers and tube preamp overdrive pedals (which sounded creamy on solid state amps and even a Twin I played through) now sound too harsh and are clipping badly through the BJ III. I even turned the volume to 1 on the BJ and the clipping sounds too harsh, not creamy and smooth.

    Question 1: So is this amp defective from the factory or is this just the nature of the design (too much inherent distortion)?

    Question 2: If the amp is not defective, will it get better with the basic mods?

    Otherwise the amp sounds pretty good in all other aspects when the overdrive pedals are not at full blast. Thanks for you reply in advance Bill.

    • bill says:

      The Blues Junior is a high-gain amp. The basic mods will help it take pedals better, but it’s still a high-gain amp. You have to be very gentle with pedals, especially the level. The BJr’s natural distortion tone is bluesy grind. If you want creamy, get the tone you want from your pedal and keep both the amp’s and the pedal’s volume levels as low as possible. Open the master volume all the way.

      • Eric Bernhardt says:

        Thanks, I may also explore putting a 12AY7 in V1 in hopes to clean up the signal. I’m reading on the valve page that many folks like this tube there.

  26. whiplash43 says:

    Do any of your mods, coupled with a speaker change, bring the clean sound of the BJ closer to the Vox clean sound? I love both the clean, blackface Fender sound and the clean Vox sound, but I don’t like lifting and toting a 50 lb. AC15 around. The BJ has the full tube and light weight going for it.

  27. Gitaryzt1985 says:

    Thanks for the review Bill!

    I bought a Blues Jr III last week and am gigging it at my church. First overall impression is that yes, it is VERY bright and extremely thin and harsh at giggable volumes. Also, at the church I noticed that I it is extremely bright directly in front of the amp, which is to be expected, but the harshness is almost unbearable. Take two steps to the side, and the tone is so muffled that it makes me wonder what the audience is hearing.

    The first attempt to tame the highs was to order an Eminence Cannabis Rex speaker. I gathered from Bill’s description of the CB speaker that it was the one for me. Secondly, I ordered a Weber Beam Blocker just because the only place I can stand at church is directly in front of the tilted amp, so I’d like to see if that helps save my ears.

    Finally, I ordered Bill’s Cream Basic Mod Kit today and I am looking forward to getting it in. The boxiness (uni-directional) sound from the amp is really distracting for me while playing live.

    Thanks Bill for all of the info and help to all of us Blues Jr owners out here!

  28. DetroitBlues says:

    So here’s a good question that I’m sure no one has asked yet. Granted any Blues Jr. will require mods, should someone look for the previous model Jr. and mod it or buy the new one and mod it? I’ve consider purchasing a stock older Jr. and mod that one instead of purchasing their “tweed” or v.III models… Would I benefit using their already “upgraded” models?

    • bill says:

      New or old, the results will be pretty much the same. The cream board Blues Juniors (since 2001) are a bit easier to modify, and you can make it sound exactly like the Series III by removing C9 and jumpering C10. The only difference with the tweed model is the speaker. The early green board amps sound somewhat darker.

  29. elissaios says:

    i just bought a fender blues junior iii.Today i watched this video
    and now i am thinking that tweed nos blues junior is a better sounding amp.So if i will change speaker to blues junior iii to a jensen c12n i will have the same sound with tweed nos version?


    • bill says:

      I don’t think the video is an accurate guide to the sound quality. Let your speaker break in, then see how you like it. I suspect that the black tolex Blues Junior in that video is an older green board, which is why it sounds darker. But yes, if you put a C12n into your BJR III it will sound like the NOS. Just turn down the treble a bit.

  30. yan says:

    Hi Bill,

    do you think it is possible to desparkle the classic cream board – the one before series III, with 1500pF).

    I know it is not a feedback that acts on signal overshoot like the presence control does but could it be an effective way to cut some painful single coil brightness ?

    so no need to lower the guitar’s volume 😉


    • bill says:

      Cutting the treble isn’t enough? What about the tone control on your guitar?

      I can build you a tweed-style tone control that replaces the 1500pF cap, so you can cut as much treble as you want, after all the other controls are set. Email me if you’re interested.

  31. yan says:

    yes I already use the tone control to do that. It sounds good this way.
    but if there was a possibility to make the overall sound “less bright” I would be interested.

    maybe a tweed-style tone control is better than the presence control.
    As I cannot send my amp to you I will look at the tweed-style tone control principle at first.

  32. Aaron Flynt says:

    I’m considering doing a “Sparkle Mod Reversal” on my new Humboldt Hot Rod Series III Blues Junior. Even with the C-Rex speaker it sounds too bright for my tastes. Would a 630v NP0 Multilayer Ceramic be adequate for C9?

    • bill says:

      Yes, all of the NPO caps are temperature-stable, so the frequency response stays the same. The voltage isn’t critical if you’re using an NPO. You might want to try a couple of different sizes, working down from the (old) stock 1500pF, in case that’s a little too dark for you. 470 or 680pF might be more to your liking.

      • Aaron Flynt says:

        Thanks for the confirmation! I ordered a bunch of them in different values from 270pf up to 1500pf from Mouser. I’m trying to think of a good way to experiment with the different values before I commit to the mod without soldering to the board and voiding my warranty. Would clipping the cap to some test leads, connecting one lead to R46 and the other to ground work (assuming I’m careful not to electrocute myself)?

        Also, I’m contemplating the TO20 OT. Would that help keep the low strings from distorting and mushing out so easily?

        • bill says:

          Yes, either transformer will significantly improve the quality of low-end tone. They work best in conjunction with the basic mods, of course. Power supply stiffening is essential for strong bottom end.

  33. yan says:

    Hi Bill,

    I heard about series III that are now equipped to EL-84R (wrong info or not ?)
    I heard about EL-84S too on other amps…

    I’m completely lost 😉 I was wondering about the difference of these opposed ‘classic’ EL-84 ?

    is it just the name ?

    all of these tubes can be swapped in the power section of the BJr ? (I have the simple cooler bias with the bias resistor swapped)


  34. livingwater says:

    I purchased the Blues Jr3 amp in December.
    I’m not interested in distortion but would love to get the amp to sound like my Vox valvetronic with the boutique CL effect. I like to get full control over the treble, bass and mid independently to give me more tone over the full range of the master volume.
    I presently run the preamp volume at 2 (minimum)
    I purchased so of your mod’s which are forthcoming.
    Can you tell me what mod’s I should buy to achieve the above (if it is possible with this amp)


    • bill says:

      The basic mods and presence control will give you the widest range of adjustment and will considerably improve the stock tone. If it’s too bright, the sparkle control takes care of that.

      I don’t have a Valvetronic; can’t help there.

  35. RogerJ says:

    Bill, as posted under the tubes section today, I’ve just got a new BJnr III, and yes it is bright! If I turn the all the tone controls right back to “1” it sounds a bit like my old green board Pro Junior (which sometimes I may want) but in any case I doubt I’ll have treble much above “3” at any time. Am I losing the essential sound of a BJnr by rolling off so much treble, or is this an acceptable thing to do? I will almost certainly do some of your mods, but as the amp is new and of course under warranty I’d like to wait for a while yet.


    • bill says:

      With all the tone controls off, all your getting is a small amount of mids. That kind of setting limits the volume of the amp and yes, I think it misses the essential tone of the Blues Junior. On a stock amp, I run the bass at 8 or so, treble at 6, mids anywhere from 4 to 8. In a band setting, I would probably turn the bass down so I don’t compete with the bassist or keyboards.

  36. tele_pathic says:


    Great site, wonderful info. Look forward to getting and then modding a Blues Junior in 2012. I do have a question that I’ve not been able to find an answer to: Is there a Blues Jr. II? I get the date codes and the idea that first the green boards with less-than-ideal reverb circuitry, then the cream board with the “fixed” reverb circuit. So I see the Blues Jr. I and the Blues Jr. III, released in 2010, right? Is there a Blues Jr. II, or did Fender jump straight from I to III?

    Thanks Billm, or any one else who has this answer.

    • bill says:

      Fender never called the original green boards “I” or the cream boards “II”. But since they started calling the BJrs introduced in September 2011 “III”, it makes sense to think of them that way.

      So all the cream boards between 2001 and early 2011 are “II” by default.

    • bill says:

      Fender never called the original green boards “I” or the cream boards “II”. But since they started calling the BJrs introduced in September 2011 “III”, it makes sense to think of them that way.

      So all the cream boards between 2001 and early 2011 are “II” by default.

  37. livingwater says:

    I recently purchased two (2) spring wire tube retainers to replace the existing larger steel retainers that are on my Blues Jr3 Are you familar with this type?
    My Super reverb had spring clips that held the base of the tubes in place.
    Why did Fender decide on using the retainer plate that covers the entire top of the tubes with funky springs holding it in place?

  38. stan says:

    what can anyone tell me about this newest edition of the BJ called

    Fender FSR Blues JR III TT 30w Tube 1 x 12 Combo Amp – Limited Edition Blonde Top

    what y’all think

    does it need the usual modes?

  39. Steve D says:

    I just bought a BJr III (western… oooo fancy tolex, actually it’s pretty nice aesthetically I think) and yes, very bright.

    I wanted to mention that I’ve been able to ‘dial out’, for lack of better term, the harsh sparkle with guitar controls (as opposed to modding the amp right off the bat). I’m playing a strat I built up, van zandt single coils, push/pull neck on switch (1st tone knob), and I replaced the 2nd tone knob with a passive midrange shaper (courtesy of Rothestein guitars). Between the tone knob and passive midrange, I have what feels to me, to be a huge amount of control over the “sparkle” for single coils. Just wanted to throw it out there. I’m still going to do some mods to the amp down the road, mainly for the sparkle since I’m still rolling the treble back on the amp more than I’d like to, but guitar controls shouldn’t be overlooked by players either (guitar mods are fun too!). Thanks for all the info Bill, your site is fantastic.

  40. leo says:

    Hey Bill Great site. I bought a BJ tweed NOS and after a week the tubes cooked. Took it back got another one plugged it in and the tubes cooked in 30 minutes( 2011 models). I really loved the sound that the NOS provided so that is why I went back to get another. Again sound is a preference and everyone is different. Was so bummed I found a BJ 2008 model on ebay and it has not let me down. I put in the same speaker the NOS has and I am fixing to change the output transformer to a Mercury Magnetics transformer. My questions are why did the tubes burn out so fast and is the 2008 model built better than the 2011 models. Will the changing of the transformer make a difference? Thank you and thank you for this site. I am a Blues Junior lover.

    • bill says:

      In what way did the tubes cook? I assume you’re talking about output tubes. Did they red-plate, or did their labels turn brown? Do you play with large amounts of distortion? If so, that really builds up the heat in the tubes. All Blues Juniors are biased hot, but the tubes that you get are the luck of the draw. You might get tubes that are naturally cold-running and they’ll last a long time. But tubes on the hot end of the spectrum can go quickly.

      V4 can toast its label very easily because it’s warmer next to the other tubes and because phase inverter oscillation is a common problem with Blues Juniors. V4 is the one that does the oscillating, so it’s running full blast even though you can’t hear anything.

      The basic mods kit has components to correct both problems: adjustable bias, and a capacitor to eliminate PI oscillation. It also greatly improves tone quality and the range of adjustment in the tone controls.

      An output transformer by itself will slightly improve the quality of the tone, but doesn’t change any other aspect of the amp. The Mercury is actually a Deluxe Reverb output transformer. It has nice clarity. You have to drill holes to mount it; it’s rather large and bulky and doesn’t have end bells. It’s also ridiculously overpriced. The TO20 transformer that David Allen and I designed is specifically for the Blues Junior — it’s a drop-in. It does bass better than the Mercury and has the same clarity through the rest of the range. Whatever output transformer you get, I strongly recommend the basic mods first. There’s a lot of good tone bottled up in the Blues Junior, but the OT is not the primary thing that holds it back.

  41. bucky katt says:

    I am looking at going up to GC to buy a new Blues Jr this coming week and i need to know if the new ones will work with the octal socket mod. i love the blues JR but after playing through one with a set of 6v6’s with your mod, i was hooked. i wont buy new if i cant do that tube socket (and a few other mods) on it.

    • bill says:

      All current Blues Juniors can be modded for octal conversion. Old green boards (2001 and earlier) can’t, at least not by a kit. We do it here in the shop, though.

  42. britbeat says:

    hey up there Bill
    Firstly im LOVING you site great place very helpful.sssOOOO Ok I have just purchased a brand spanking new ”fender blues jr 111 after the goldrush” very gold and has the celestion greenback …., – i dont play blues or even much lead but i do love english style rhythm guitar chords ie- lennon townsend richards kinks that kinda thing etc…string slashings.. so im glad i got this AMP.. imk thinking i should do the mods like the twin stack mod cause i luv that sound and it seems easy to get done- im up for more mods what do you think would suit my sound?? look forward to hearing from you

    • bill says:

      The basic mods (including the TwinStack) will bring out a broader range of tones. The presence control is handy, too, for making the amp even more aggressive, or for dialing it back to a softer tone. The TO20 output transformer will improve quality of the tone across the board, but it costs more to mail to NZ, of course.

  43. PansORama says:

    I see my BJiii has a Beltron reverb tank in stead of an Accutronic. Is replacing it with a MOD tank still worth the effort as an upgrade?

    • bill says:

      Belton now owns Accutronics. They said that they would continue making the Accutronics-style innards (three springs, flat) for Fender, not the Belton/MOD style, with three springs in a triangle/pyramid arrangement. So the MOD tank will still sound different.

  44. PansORama says:

    Ok thank you for clearing that up. I hope the MOD tank sounds a little less ‘metallic’…

  45. Randy says:

    Hello Bill-
    Thanks again for all the info! Great site. Have you seen/looked at/examined the “Humboldt Hot Rod” (Bjr III) from Pro Guitar Shop in Oregon? Hemp speaker, sparkle mod…Demo sounded good, so ordered one, and it came yesterday. Haven’t tried it yet. Mods needed? Any thoughts/opinions greatly appreciated!
    Thanks for your time!

    • bill says:

      The Humboldt Hot Rod is just a standard Blues Junior III with a Cannabis Rex and pretty green tolex. All BJr IIIs have the sparkle mod. See my page about the BJr III.

  46. shawn says:

    NOS vs BJr 111?

    I am looking for a small amp that sounds nice. I realize that it will be modded and update over time. I just tried a Vox AC15 and thought that I would LOVE it, but instead, I hated it. Maybe I got a lemon. I am worried about clean head room on a 15 watt, but if you were buying a Fender BJr, which would you go with? I wouldn’t mind a Blues Deluxe, except more weight, more money and the HR Series series to get quality control/failure complaints?

    NOS or BJr 2 or 3?

    Wasn’t sure where to post this. Thank you!!

  47. shawn says:

    The Excelsior is a fun project amp. (BTW, I did just order the tone mod and the new transformer.) Wasn’t sure if I could depend on it as a gigging amp. That’s why I also starting looking at the Blues Junior.

    From what I have been reading, the Bjr 3 would be better than the NOS? Still may try to grab one off ebay someday.

    Lastly, I do you recommend replacing the speaker lead on the excelsior? I saw someone selling a tail like that for 40 bucks! Crazy!!


    • bill says:

      The Blues Junior III and NOS sound the same after the mods.

      I think the Legend 1518 speaker makes a huge improvement in the tone of the Excelsior. Makes it louder, too.

  48. 66Esquire says:

    Hi ya’ll,

    Just got hold of a used BJIII over here in UK.

    You’re absolutely right about the Lightning Bolt being similar to the Red White and Blues. I found that the G string sounds disconnected – totally out of balance – and near to nil bottom end. That together with the C10 and C9 stock board changes you mention makes it complete overkill, chainsaw like edge, no subtlety whatsoever… cheap and shriiiil..

    Done basic mods, swapped out for a cannabis Rex and MOD reverb – different animal all together now!

    Also, Fender wire these to 230v mains because apparently we’ve changed – NO – we haven’t changed anything, only the spin to conform to EU requirements. When I plugged mine in the valves could illuminate your house and an unpleasant smell like boiling beeswax or pig fat filled the place. I’ve rewired it 240v and it runs cool now. Had the same problem with my USA 1995 Blues DeVille. That cooked several times and took out part of the track on the PCB – it’s partly hardwired now.. and set at 240v.

    Anyways… thanks for your insights Bill and feedback from all the guys that contribute.

  49. bbqbrisket says:

    What is the difference between II series and NOS series?
    Also speaker replacement for surf music:
    Cannibis Rex or Swamp Thang?

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