The Right Speaker for your Blues Junior

Aftermarket speakers, like tubes, are not really a mod.  But they do change the way your Blues Junior moves air and the tones that get emphasized. They may partially mask an amp’s flaws, but the right approach is to make the amp sound great first, then use the speaker to give it that final push in the tone direction you want to go. It should be your last mod, not your first. People who say that a new speaker has cured the Blues Junior’s inherent boxy tone simply haven’t heard a Blues Junior with proper tone stack and power supply mods.

See the bottom of the page for easy instructions on how to change the speaker.

My customers and I have collectively tried many different speakers, but I’ll limit my comments to speakers that I’ve spent some time with and have a feel for the tone.

Fender Special Design (stock speaker)
This is the stock speaker in all black and blonde Tolex Blues Juniors and old green board tweeds. The speaker is made by Eminence and it’s roughly equivalent to the Legend 125/1258. This speaker has been used in hundreds of thousands of Fender amps, including the Deluxe Reverb, Hot Rod Deluxe, Twin Reverb, Blues Deluxe, and many others. It’s a decent, all-around speaker. It doesn’t have the deepest bass, and the highs can sound kind of fizzy, but it’s well balanced. Many people decide to leave it alone after they do the mods. The “farty” tone in the bass of a stock Blues Junior is mostly due to poor design decisions in the amp, not flaws in the speaker. One surprising new observation about the stock speaker: The more power you give it, the better it sounds. My 5881-powered 25-watt Blues Junior has the stock speaker in it, and it sounds awesome. The Billm basic mods will go a long way to helping this speaker deliver. Many owners who have upgraded to 6L6s and are running a full 30 watts find the stock speaker comes to life and they don’t need to change it.

Jensen C12N (stock in tweed limited edition and “NOS” models)
This reissue Jensen is built in Italy by Recoton. They’ve made an effort to capture some of the old “American sound” magic of the Jensens that were so popular in the 1960s, but they fall short in some significant areas. The C12N starts out well in the bass and transitions well to a smooth midrange, but this speaker can be downright shrill on the high end, especially with a Tele or Strat bridge pickup. On the plus side, the C12N cuts well in a band situtation and is less likely to be buried. It sounds better after a lengthy break-in period, but it’s definitely not my favorite speaker.

Eminence Texas Heat
The Texas Heat is one of the most popular of Eminence’s line of Patriot speakers, and for good reason. It has great tonal breadth, strong bass, prominent, slightly smoky mids, and a smooth top end. When The ToneQuest Report tested a bunch of the Patriots a couple of years ago, they reported that the Texas Heat improved every amp they tried it in–and they tried a lot. It’s more efficient than most other aftermarket speakers, so you get your 15 watts’ worth. The only criticism I have of the Texas Heat is that when playing clean, the highs can sound a bit disconnected from the rest of the tone, almost as if my high E string was connected to another, smaller speaker. It sounds better if you roll off the bass and boost the mids a bit to fill it in. And when you crank it, distortion tones are sweet, not spiky and harsh.

Eminence Cannabis Rex
The Cannabis Rex gets its name from its hemp cone. Hemp fibers strengthen the cone and impart a different flavor than typical paper cones. The cones are made for Eminence by Tone Tubby, the leader in hemp-cone speakers. This is the warm/clean jazz speaker! It’s a great clean speaker, but its cleans have that hemp cone personality–soft-edged, but not mushy.  It handles overdrive and distortion very well when you push it. It’s very efficient, one of the loudest speakers you can put in an amp, and it pushes out pretty, round bass notes really well. The top end is very sweet, even forgiving. This speaker couldn’t make a harsh note if it tried and is beautifully balanced bottom to top. Super for creamy lead work.

Eminence Red White and Blues
If your idea of electric guitar is crisp, bright, staccato bursts, clear, sizzling chords, with lots of top-end sparkle and tight, tight bass, this is your speaker. One player’s “tight bass” is another’s “no bass,” however. So if you like booming lows that flap your pants legs, that you can feel in the soles of your feet, look elsewhere. This is a great lead guitar speaker for many kinds of rock, searing bright country, or to clean the mud off your humbucker tone.

Eminence Swamp Thang
There’s nothing swampy about the Swamp Thang–this is the loudest, cleanest speaker in Eminence’s lineup, but its response is tilted towards the bass side. Eminence calls the treble response  moderate, but I find its highs more prominent than the Texas Heat’s. It produces big, round lows, even in the BJr’s small cabinet. The magnet is huge and it will add noticeable weight to your BJr. It might hit an aftermarket, larger output transformer like the Heyboer I use. You can probably spin the baffle 180 degrees to place it at the lower right instead of upper left (from the back) for clearance. I use the Swamp Thang on my test bench because it’s so clean (I want to hear the amp, not the speaker) and the moderate highs keep the ice pick tones out of my ears. The Swamp Thang is not a truly neutral speaker; it adds a warm, woodwind-like undertone.

Eminence GB12/GB128
This speaker from the Legend line is Eminence’s take on the famous Celestion Greenback. It’s an improved, affordable Greenback, with great, deep, lows, that classic British smoky tone, bass that manages to be fat and round-toned without being overpowering, strong mids, and nicely restrained highs. It may be one of the best speakers you can buy for blues tone.

Eminence Wizard
I don’t see many British-voiced Eminence speakers in Blues Juniors, but this one is pretty interesting. The bass is firm, with an aggressive edge to it, not round like the Cannabis Rex, GB128, or even the Jensen C12K. The highs are bright and crisp, also with an aggressive edge to them, like the Red White and Blues, but with more bass. And in true British fashion, the midrange is colored, too. Not smoky, like a Greenback, but an interesting, textured tone, rich with harmonics. This is a very efficient, loud speaker and if your Blues Junior is getting buried, this might just be the thing to unearth it. If you like mellow, stay away. If you like to peel their eyelids back with your bridge pickup or put a serious edge on your neck or ‘bucker tone, this one’s for you.

Eminence Lil’ Texas
Want to put your Blues Junior on a diet but not sacrifice tone? The neodymium-magnet Lil’ Texas is over 4 pounds lighter than the stock speaker and sounds better than the Special Design or the C12N. It has a nice, clear American voice that covers rock, blues, and jazz. It benefits greatly from the basic mods to open up the bottom octave; it sounds a little gutless in a stock Blues Junior. It has a smooth top end, sweet midrange, and firm, non-boomy bass. Eminence says it’s good for country, but I’d choose the Red White and Blues for searing leads. It’s nearly as loud as the Swamp Thang; when I plug both in together, it hangs right in there. For a lightweight extension cab, the Lil’ Texas can’t be beat.

Celestion Greenback
The Greenback (G12M) has always been a good choice for the Blues Junior. It’s a bit quieter than some of the newer designs, but the classic, warm British tone is there in spades. This is the speaker that defined “smoky,” that coloration of midrange tones sought after by blues and blues rock soloists. A classic.

Celestion Vintage 30
The V30 was one of the tone pillars of the classic rock era: huge, powerful mids and early breakup. Four of these in a half stack and you were on your way to rock god status. But they were often tempered in half stacks by a pair of Greenbacks to fill out the bottom end. The V30 has less bass and less treble than the stock Special Design speaker. Fender chose the V30 for the Texas Red special edition of the Blues Junior and you can hear the difference right away. It’s a standout for lead guitar and for rhythm guitar that stays out of the way of the bass player. If you like thumpy bass or need clean headroom, look elsewhere. Some players say they get more clean headroom with the V30, but I think that’s because the mids are prominent and that’s the most sensitive area of our hearing, so it sounds louder.

Celestion G12H Heritage
The G12H Heritage looks superficially like the G12M Greenback, but it’s a much different speaker. And the G12H Heritage is not the same speaker as the G12H. The Heritage is made in England and the non-Heritage is made in China. Anyone who has heard both will tell you that the Chinese-built G12H is a very nice speaker, but the Heritage is noticeably better. The G12H Heritage bass response goes down to 55Hz, and it can keep up with the Eminence Swamp Thang for rich, deep lows. The highs are clear and bell-like, and can be surprisingly bright if you crank the treble. The overall frequency response is flatter than the G12M Greenback, which has that famous midrange hump. With the G12H, the midrange response is up to you. With the mids dialed back, you get a clear, Fendery scooped tone that supports clean playing beautifully. The speaker is very responsive to mids, though, and if you crank them, you’ll get plenty, maybe more than you bargained for. On Blues Juniors and other Hot Rod series amps, the TwinStack mod is essential. This is an expensive speaker, but it covers the range of American and British tones perfectly.

Jensen C12K
The C12K is Fender’s current choice for the Deluxe Reverb reissue. It sounds somewhat like the Texas Heat, but much more restrained in the highs, maybe even a little dull-sounding, a little more color in the mids, maybe a little dirtier in the bass. But there’s an impressive amount of bass on tap; with a bit of roundness, like the Cannabis Rex. It’s like a rude version of the Swamp Thang, but the ST is a much better speaker overall. This is a loud, efficient speaker. Like the Swamp Thang or Wizard, you’ll feel the increase in weight because of the huge magnet. Compared to many other speakers, the C12K sounds kind of lifeless. It properly tames the highs of the Deluxe Reverb, but doesn’t bring much to the party.

Weber California
The California is Weber’s clean-and-loud speaker, patterned after the great JBL D120. Like the Swamp Thang, it does what the amp tells it to do, but it’s more balanced  in tone and brighter. It’s available with an aluminum dust cap, like the original JBLs, but don’t go there! It’ll be way too bright and beamy.

Weber 12F150
The 12F150 is Weber’s idea of what a vintage, US-made C12N would sound like if it were offered today. It gets that brash voice-of-rock ‘n’ roll American tone right, and it’s a popular choice among rock and blues players. Bass is solid, mids are somewhat scooped, highs are bright and clear. One potential point of confusion: the many choices of cone and doping options can greatly change the tone.  So two players comparing their 12F150s may almost be discussing apples and oranges. A call or email to Weber’s tech staff will get you the right ingredients for your tone, though.

Weber 12A125
I was prepared to dislike the 12A125 based on my experience with other light-coned alnico speakers: no bass, early, unharmonic breakup, etc. I tried it in an unmodded Blues Junior and was unimpressed. But after the mods, the 12A125 really surprised me. If you’re looking for a fast,  responsive, bright speaker that just oozes Fender “spank,” this is your speaker. It’s bright, like the Eminence Red White and Blues, but it has a nice, crisp bass, like a tenor who can hit clean, clear low notes, not a deep-voiced baritone. This is an inspiring speaker for bright, clean playing–I heard things from my Tele bridge pickup that I don’t think I’ve heard with any other speaker. The highs get great support from the mids, but the voice is pure American, not a hint of British smoke or thickness. Yes, you can go too far with the bright stuff and make it painful, but that’s what tone controls are for. I had a harder time finding a good overdrive tone with this speaker because it doesn’t like complexity. I had my best results starting with the tone controls off and either the bass or the mids up full. then dial in just enough of the others so it doesn’t sound thin or muffled. Get one of these, plus the basic mods, and kick some Deluxe Reverb ass! This speaker is everything the Jensen P12R wished it was.

Jensen P12R
Fender chose this speaker for the Relic Blues Junior version. The Relic looks like it was made in the 1950s and lived a very hard life, complete with rust, stains, cat-clawed grille cloth, and tattered tweed. The P12R sounds like it’s from the 1950s too… kind of like an old table radio. This speaker makes the Blues Junior sound like a kazoo on steroids: squawky, nasal, thin, and weak. If you like that old-timey sound, you’ve found it. For the rest of us, yuk.

Speakers that Don’t Fit:

Eminence Red Fang

Eminence FDM (Flux Density Modulation)

Tone Tubby Alnico

Celestion Alnico Blue (sometimes juuuust barely fits!)

Weber Blue Dog (seen ‘em fit, seen ‘em hit the chassis)

How to Change the Speaker

1. Leave the back on the chassis.

2. Remove the screw that holds the reverb wires to the side of the cab.

3. Unplug the reverb wires. Note that the red plug is towards the middle of the amp.

4. Unplug the speaker.

5. Lay the amp on its back.

6. Remove the two side screws and remove the two top screws.

7. Reach under and hold the back panel down as you lift the cabinet off the chassis. THIS DOES NOT EXPOSE ANY ELECTRONICS OR HIGH VOLTAGES.

8. Remove the old speaker.

9. Replace with the new the speaker. When tightening, just use enough force on the screws to lightly compress the gasket. If you make it crusher-tight, you’ll distort the frame and maybe ruin the speaker.

10. move the plug to the new speaker. The red dot goes on the + terminal. Reassemble in reverse order.

382 Comments

  1. teza says:

    Hi Bill,
    finally went for a texas heat, what a change !!! All the mod are there now, the good thing about that change is am going to keep the stock speakers because I do agree with you is not a bad speaker even if you can find better of course, and maybe put it in a extension cabinet, let see.
    Other change I made, it’s the valves, I’m now running a 5751 Phillips Jan on V1 and Tung Sol for V2, V3 and that sound really good, I can push the preamp a little bit more before distortion arrives and keep a nice bluesy clear tone, Am using as well a tube screamer set up as boost, here we go really nice blues tone. so now the questions.
    Is it possible to change the tone of the fat, to have more midrange and less bass? That’s why am using a tube screamer instead witch for me sound a lot better.
    Another one for the road, living in UK, I found a guy in Manchester who doing cabinet for the Blues Junior and extension cab as well
    for a very good price,(can have it in tweed) but don’t know if the wood is using is ok and need your advice.
    “The cab is made from Maple and back panels from Iroko.The Baffle is made from quality Birch ply”
    What do think ?
    Thanks for helping.
    Teza

  2. Arjan says:

    Well, after having done the basic mods on my Blues Junior II, upgraded the output transformer, changed the master volume taper, replaced the broken stock reverb tank with the Ruby Tubes model (and changed the reverb taper) and added the Presence Control, I was impressed with the improvements. More, better, tighter bass, more clarity, lovely reverb, proper tone control. Did I say tighter bass? Can’t recommend replacing the OT enough!

    But I still felt something was holding the amp back as the bass was still flabby and the highs lacking sparkle, so after much deliberation, I eventually took the plunge and ordered a Celestion G12M Greenback speaker. My God, what a difference! It’s like I finally took the amplifier out of its box! Compared to the G12M, the stock speaker sounds like a muffled cat wrapped in a beach towel. Honestly, I wouldn’t normally dare to disagree with Bill, but the speaker replacement if a must if you want the best out of this amp. Saying this, and this is important, only do this after you’ve done the recommended mods. An expensive speaker isn’t worth the money unless you’ve first given the amp proper tone control and upgraded the power supply caps (=basic mods) and put in a proper output transformer. And then there’s a plethora of speakers to choose from; I’ve chosen the G12M because I play rock and blues, but there’ll be a better speaker for whatever you play. See the list provided by Bill.

    I’ve had this speaker installed since Christmas now and it’s only getting better. The Stock Speaker is going on eBay UK soon, as (unrelated topic) is my Ibanez/Keeley TS-808 Mod Plus. I’m sure it’s a cracker pedal if you can crank up the amp onstage, but at the volumes I play these days (at home mostly), I’ve fallen for the Fulltone OCD.

  3. jharrington1222 says:

    Hi Bill,

    I’m considering the Eminance Texas Heat, which looks like a 150w speaker, and I’m also considering possibly 2 single cabs that I can daisy chain together. You say that the Texas Heat is very efficient and that it would give you “your 15 watts worth.” Given that the amp is only 15 watts, is this too much wattage? Would adding a second cab allow me to get more volume out of it?

    Thanks for your help.

    Jim

    • bill says:

      You can’t have “too much power” in the speaker. The wattage just tells you how much it will handle before it melts. The sensitivity (dB at 1 watt at 1 meter) tells you how loud it is.

  4. wabusk says:

    Bill, I have a ’99 green board BJr and an LP with P90’s. I prefer the warmer sound of the green board and wondered what your thoughts were on speaker replacement. I was going to go with an Eminence gb128 based on your various speaker evaluations. I prefer that fat warm tone of ZZ Top vs the sparkly, jangly, country sound.
    Any input would be appreciated,
    Thanks

  5. Tridyed says:

    Well I took the leap and got a Blues Jr. today and I decided to grab the Special Edition version since it had the Rex speaker in it. I am pretty happy so far but I can’t wait to do some of the mods. Which board do they put in the special edition?

    Also I am guessing you can do pretty much any mods to them just like the regular Blues Jr’s ?

    Bill if you have a moment which mods would you suggest doing first ?

    Thanks for any info… gathering cash to send you for a few of them to get started.

    Peace out.

    • bill says:

      All Blues Juniors since 2001 use the same cream board. They’re identical inside.

      The Basic mods, a TO20 output transformer, and a presence control will make it sound remarkably better.

  6. jagpessoa says:

    Hi Bill,

    I would like your opinion on the stock speaker cable.
    It looks so flimsy… Is it worth replacing it?
    Does a better quality cable with a better jack will have a better sound (as in guitar cables)?

    Thank you

    Joao

  7. PansORama says:

    Hi. I read somewhere that the Lightning Bolt that Fender puts in the Blues Jr III is in fact an Eminence Red White and Blues speaker, with a different label glued on it. Does anybody kmow if this is true?

    I put a Cannabis Rex speaker in myself, but the stock speaker sounded pretty ok.

  8. vinic says:

    Hi Bill,

    Could you please tell me if the Celestion G12H-55 will fit in the cabinet. It’s a bit larger than others G12H and G12M and I’d like to be sure about that. http://celestion.com/product/25/heritage_series_g12h55/

    I’d also like to be sure that it does what it tells as I use a baritone guitar tuned to A=55Hz. I have tested the stock speaker with a tone generator and a sound level meter and I loose around 10dB from 80Hz to 55Hz, which is A LOT. Looking at the Celestions frequency charts, the G12H-55 doesn’t seem to be so different from others in the low end part. It’s a bit confusing…

    I would really appreciate that someone could tell me if it worth that $200 mod… or if another speaker could do the job!

    All the best

    • bill says:

      I have never used the G12H-55, so I don’t know if it will fit or how it will sound. From the pictures, the magnet looks rather large. You might have to move the output transformer to make it fit.

  9. pmurph1138 says:

    I recently bought a Swamp Thang and I’m not getting along with it at all. My Bjr. is stock except for the twin stack mod. I wanted a little more bass in the amp and something to restrain the prickly highs. (full disclosure: I play a jazzmaster with vintage wound pickups…a pretty bright, jangly set-up to begin with)

    I liked the added bottom, but the speaker seemed to accentuate a particular frequency that just kills my ears. Maybe 2.5 – 3k or so. I didn’t find it at all dark or smooth in the high end. It’s loud and clean, but I had to take it out and put the stock speaker back in.

    Maybe breaking it in would help, but I will likely sell it and get a Cannabis REx instead.

  10. Paul.w says:

    Hey all, Im new so please forgive me if this has been covered.
    I want to put a greenback in my 12year old (mex) blues jr. and was think about the heritage 20watt,
    but seeing the gold rush blues jr. has a 30watt 55imp greenback make me think they know some thing I don’t.
    Any thoughts ?
    Thanks for any help, Paul.w

    • bill says:

      I think the Heritage speaker is just too expensive for a production amp. I’m sure it’s a nice speaker, but I’d never spend that much.

      • Paul.w says:

        Im in Australia.
        The Heritage 20watt and 30watt are both between $180 to $199.
        Yet the standard non English made greenback is $140.
        Im not sure if the 20watt will brake up to early, and this why fender went with the 30watt to maintain the clean.
        The 1974x I had sound great with the greenback 20watt.

        Thanks, Paul.

        • bill says:

          $40-$50 is a big difference at retail. I haven’t heard the speakers side by side, so I don’t know if one has significantly more headroom than the others, but most everyone agrees that the Heritage line sounds better.

  11. Paul.w says:

    Hello bill, is it possible to run a blues jr. speaker as well as an extension cab ? Thanks.

    • bill says:

      Yes, the aux speaker jack puts the two speakers in parallel, for a 4 ohm load. Tube amplifiers can handle a 100 percent mismatch, so an 8 ohm amp can drive 4 or 16 ohms with only a small loss in performance. For maximum efficiency, the TO22 output transformer has 4 and 8 ohm taps, and comes with a switching jack that automatically switches to 4 ohms when you plug in the second speaker.

  12. fabiogodi says:

    Friend, I have a blues jr NOS, I live in Brazil, which modification you indicate to me in my amp with the speaker to sound like a hot rod or tweed, hot and creamy. Thank you.

  13. RussB says:

    Hey Bill:

    Great site! Thanks for taking the time to provide your insight.

    I just purchased a BJ III. I’m definitely not a “tinkerer” and am not very mechanically inclined; however, I think I can handle swapping out the speaker. I’ve decided to go with the Cannabis Rex. I read somewhere that they take a long time to “break in”. What does this mean? Is there something I should do before installing it to help it “break in”.

    Sorry for the newbie question. Thanks!

  14. joem789 says:

    It is truly confusing when trying to select an Eminence speaker. I checked out their tone guide which was entirely unhelpful. And I do think they are surprisingly inaccurate about their speakers. Especially regarding the low end and high mid peaks. People often already know what to choose when looking at Celestions. But of course they are often twice the cost (at least). I once had the Eminence Legend 12’s which weren’t bad. But they were too bright and the low end just wasn’t there. I later had Red Coats which sounded good. But they had too distinctive of a sound that leaned towards British.

    The Celestion Seventy 80s that often come in amps are a very neutral sounding speaker, which translates to being a good thing. But of course they aren’t that great overall. They have their weaknesses. I am trying to find an Eminence that has a very neutral sound. But still having good tight bass, and good clean without piercing your ears with peaks. Of course not too tight in the middle. Something that can do american and british sound. I play a lot of bottom string tele picking with some heavy low end (2×12). But I also play a lot of blues and hard rock on a strat. Would be nice to find this speaker for under $100 a piece.

    • bill says:

      The Cannabis Rex is my choice for smooth, with that slightly softer sound imparted by the hemp cone. The Wizard would be my choice for the same tone profile in a harder, paper cone. One thing about the Eminence Patriot series is that they’re all loud, highly efficient speakers, and that can lead to some sonic spikes that stand out in ways that some folks find irritating. The less-efficient Legend series speakers may be worth considering in that case. But a number of my pro customers use the Cannabis Rex because of its overall smoothness.

  15. bigcribber42 says:

    I have a Blues Junior NOS and I want a new speaker. Looking into the Eminence Cannabis Rex or Red, White, and Blues. I play a lot of Clapton, Bonamassa, ZZ Top, Eagles, Stones, Cream, type stuff. Any suggestions?

  16. BufordBluz says:

    Hi Bill, great site and great stuff. Another speaker question and maybe a related technical one. I bought a mint BJ3 blackface with a Celestion G12 V30 in it. It seems a bit thin, not much bass response, like your speaker info indicated. It really sings at volume but more full bodied would be better. I also have a Fender Deluxe Vintage Modified, 40 watt with standard Celestion G12P-80 in it. It has a nice warm, full bodied sound. I was wondering if the G12P-80 would be better for a richer, deeper sound for the BJ3 ?

    Also, tech question here, the BJ3 has 3 12ax7’s preamp tubes while my two channel Deluxe VM only has two. Does that, and the wattage difference in the amps have anything to do with how “warm” or “thin” the speakers sound ? Any suggestions or advice would be greatly appreciated. Thanks so much for your time

    BB

  17. chuckthebassman says:

    hi bill I have a cream board blues junior, it was the first run tweeds with the Jensen, I have done your basic mods, the low profile allen output transformer, c 10 mod, etc. I have read most of the comments from this page and I love this site, I have two mods I haven’t seen talked about here, each made a huge difference in my amp. the first was putting a black widow speaker just cleared the output transformer, large 4 inch voice coil it moves the air, this is the best sounding speaker I’ve seen in one of these amps, and I haven’t seen you test one. It sounds awesome. It made my amp into a monster, and can compete with anything 30 watts and below. One other mod which made a huge difference was putting the reverb tank in a bag, unhooking the reverb tank from the wood and putting it in a bag made a huge difference in the clarity. I think it keeps the springs from vibrating. Very cheap mod, huge difference, try it. Thanks for all your great stuff, I think I have one of the best blues jr.’s ever. – Chuck

  18. Dugbert says:

    Hi Bill,

    I recently put my SCXD into a a Princeton 65 cab with good results, even with the stock speaker. I want to upgrade my Pignose GV40 to a 12″ also. I’m building a cab and would like your opinion on a budget priced (under $100) speaker 12″ speaker.

    Thanks,
    Doug

  19. jlhbs says:

    Bill, can you explain further what the impacts of having a 16-ohm load would be to a Blues Junior? I’m trying to build what I call a “branched waveguide” speaker cabinet (translation: wad of PVC pipe) to drive from my BJ and I’m thinking about using a midrange compression driver. Among what I’m seeing on eBay, the one whose frequency response goes down much lower than most (100Hz-8kHz, unless that’s a misprint) is 16-ohm.

    • bill says:

      A 16 ohm driver is a little less efficient because the impedance reflected to the tube plates is not a match to the EL84’s impedance. The TO20 output transformer might help because we spec’d the output impedance a little on the low side. Thus there is less loss with a 16 ohm speaker.

      • jlhbs says:

        Thanks, Bill. And doesn’t the TO20 transformer open up the high end somewhat on its own? Because that’s something I’d like to have happen and if I’m going that route, I’ll likely do the basic mods and the standby switch also.

  20. Robb says:

    Hi Bill,

    I am a blues harp player and I use a modified Blues Jr. III with a Celestion Vintage 30 speaker. Taking into account I am searching for the warm distorted Chicago sound do you recommend a different speaker for blues harp or is the one I have as good as it gets.

    Thanks.

    Robb

  21. jlhbs says:

    I’m thinking about using some, shall I say, *alternative* drivers in the interest of being experimental. If I’ve connected a midrange compression driver that the specs say goes down to 275Hz, with typical distorted or undistorted 6-string guitar in standard tuning, am I going to want to put a passive highpass filter ahead of that driver or does a FBJ even send out content much lower than 275Hz to begin with?

    • bill says:

      I think you need to revisit your frequency charts. :) 275Hz is the second fret on your B string. C# above middle C. You’ve got four strings lower than that. Open E is 82Hz.

      • jlhbs says:

        I realize that, but especially with an open-back cabinet, how much content below 275Hz even comes out of a dead-stock FBJ?

        • bill says:

          The Blues Junior–and virtually any guitar amp–will produce the 82Hz fundamental from the low E. Otherwise, you’d only be hearing harmonics, and that would sound pretty weird. If your low strings sound the same on an electric as on an acoustic, you can be pretty sure that you’re hearing the fundamental. Sure, there’s low-frequency cancellation in an open-backed cab, but it’s nowhere near as great as what I think you’re suggesting.

          Guitars do have one interesting behavior: When you pluck the string you get the fundamental plus all the harmonics, but the first harmonic (2x the frequency) quickly becomes stronger than the fundamental. But the fundamental is still there and it’s still audible. You should download a spectrum analyzer program and look at the output from your amp.

          I think a compression driver would sound very blatty, with a high-midrange focus and nothing the the bass.

          • jlhbs says:

            Just to follow up, I imported the intro to Rush’s “Limelight” into Audacity and, using a spec sheet’s response graph for a similar model of the one I was considering using, gave it a 24dB/oct highpass at 275Hz and a 12dB/oct lowpass at 1800. “High-midrange focus and nothing the the bass” was pretty much exactly the result…almost transistor radio. :) It had been suggested on diyaudio.com that I make a compression driver of sorts out of this 5″ ~15W Carbonneau speaker I have lying around by making an enclosure around the back of it. Anyway, thanks for the info.

  22. Rabelais says:

    Hi Bill.

    I’m plannig to replace the stock spealer with either a Celestion G12-65, or an Eminence Cannabis Rex. Which one is better for getting rid of the ice pick?. Which one would sound better (give a fuller sound) in such a small open back combo?. Should I consider other speakers?. Many thanks

  23. barfoden says:

    When you consider a 12 inch speaker for an open back combo, two things to look for is the Q-value for the speaker and the resonant frequency of the speaker.
    The eminence RWB is described by Bill as a tight speaker in the blues junior has the resonance freq at 110Hz. A lot of the Celestions with the müller cone have their RF at 75-80Hz. The RWB’ bass will be brighter and tighter. The Jensen C12N reissue speaker is also a tight sounding speaker in an open back combo (RF=112hz).

    If you take a celestion and put in a completely closed back cab, the air can escape when the cone moves and this will provide some cushion or damping to the speaker and move the RF higher in freq. and make the speaker more neutral and punchier.

    Speakers with low q-value (0,5 or lower) needs more damping and can sound out of control and begin ghosting in an open back cab (the eminence wizard).

    A guitar amp’s bass repsonse is off-caused determined by the preamps bypass caps, coupling caps and the power stage coupling caps and output transformer. But the negative feedback loop affects the signal to a great degree.

    My hot cathode biased Laney LC30 with 4xEL84 and no negative feedback sounded glorious with a celestion G12H. The vox type power-stage at lower volume had that rich immediate class A response. Turning the volume up in goes into class AB. But the lack of NFB (speaker damping), plate driven blackface type preamp, cathode biased EL84 stage with the celestion G12H did not result in a tight funky bottom end.

    The presence and resonance control seen on some amp tailor the amount of negative feedback (damping) in the top and bottom.

  24. Wes says:

    Thanks again Bill for the candor in your speaker evals. Now with the basic mods done & decent reverb I’m in much better position to eval what I should be listening for. Music is alot of surfy stuff, country, and (only) occasionally a bit of classic rock. Trebly strat w/ 2x humbucker & couple of split positions yield some good single coil sounds. Amp not lacking in response now high or low, but that subjective tight bass is a quest; the mods made the highs gorgeous. In sort of an order I’m considering the Red White & Blues, and then toss up between Li’l Texas & the Weber 12A125. I run the mids a bit scooped anyway & have even turned them all the way down for some songs, bass & treble in about 6-7’ish.

    Anyway, thanks for helping narrow it down.

  25. Wes says:

    Thanks for the feedback.

  26. chopchord says:

    hey Bill. I currently have a Twin Reverb with vintage JBL K120s. Love that amp. Sometimes its a bit big. I just got a 95 Blues JR. Planning on some mods to clean it up and fix the reverb polarity issue. Ive heard no mention of the K120 as a replacement speaker. This amp is a closet classic and absolutely untouched.

    Your recomendations would be greatly appreciated.

    • bill says:

      The only JBL I’ve ever heard in a Blues Junior had the aluminum dust cap. It was very bright and beamy. We put a diffuser in front of it and it sounded much better.

  27. Tesla says:

    Anyone uses Celestion G12T-75 in BJ? Got good offer for two(old UK made) of them, if someone have experience with?

  28. David says:

    I’ve tried about a dozen speakers in my modded tweed blues jr over the years.
    Jensen C12n, celestion blue (take the bell cover off and it fits just fine), greenback, v30, badcat modded v30, g12h-30 anniversary, stock eminence, eminence wizard, eminence texas heat, WGS veteran 30 and I’ve finally landed on a WGS et65. Great sounding speaker, especially in the BJ.

    Next favorites would be the celestion blue, then the modded v30.

    In a bone stock unmodded blues jr I think the texas heat might be my favorite. Have fun experimenting

  29. Tom says:

    Hi Bill: Thanks for this great site! I have a newer (2008?) Blues Junior, which I love. It is 100% stock. I also have a 2009 Fender Blues Deluxe amp, also stock, which I really love. I play a Fender American Deluxe Strat, mostly rhythm, some lead in a classic rock and country band (www.loosechangesteamboat.com). I use the Blues Jr. for rehearsal, and would like to beef up the sound a bit, so that it sounds more like the Blues Deluxe in terms of tone and especially bottom end. The Jr. is plenty loud for my rehearsal purposes, but it lacks the low end beef and overall warmth of the Blues Deluxe. I can sort of get there with foot pedal settings, but I’d like to have more tonal consistency going from my rehearsal amp to my gig amp, so that I can use the same foot pedal and guitar pickup settings in both environments. I’ve read some of your Blues Jr. modification recommendations, but making the mods myself may be over my head. I have some tech skills, but I’m a sloppy solderer, and wouldn’t trust myself to do the mods that you recommend! If a simple speaker change would do the trick, I’d probably prefer spending the money on a replacement speaker rather than risk damaging the amp with my limited tech skills. What speaker would you recommend to move the Jr. closer to the Deluxe? If amp mods are the answer, what basic mod(s) would you recommend, and where do I buy the mod kits? Finally, would replacement tubes for the Jr. help me to approximate the Deluxe tone? I love your site! Thanks.

    • bill says:

      Speakers and tubes simply won’t make enough of a difference to change the tone of the amp in any meaningful way. Look at it this way: Tubes are designed to sound alike, not different. Various speakers sound different — they emphasize different parts of the audio spectrum. But if the amp doesn’t deliver low end, as with the stock Blues Junior, a speaker with lots of low end isn’t going to change much. You can’t play what isn’t there.

      We can do the mods, or any amp tech could install them.

      • Tom says:

        Thanks, Bill. That’s what I figured from reading your various pages and articles. I’ll look for a local tech to make the recommended mods, and will order a mod kit from you. Thanks again.

  30. toykat says:

    I have a much modded BJr. It has the TO22 OT, Tone stack, Presence, Orange Drop filter caps, Standby switch and of course the Jewel bulb. I have a separate cab with a Warehouse Guitar Speaker G12C/S in 16 ohms. This speaker is glorious…Smooth cone – rated at 75 watts – kind of link a Fane. The BJr sounds great when I run it through the cab. My question is – I want to install it in the BJr…Will it do harm to my amp???

    Thanks!

  31. dpowell24486 says:

    I have been looking at some custom made 212 and 410 cabinets for the Blues Junior on ebay. They are pre-made to hold the chassis and reverb tank of the BJ, but look like a Blues/Deville 212 or 410 cabinet. I have been thinking about getting one, but I have not decided which speaker arrangement would be best suited for optimal BJ tone. I mainly play at church and sometimes have a hard time cutting through the mix when a drummer, bass player, and another guitar player is involved. I would need guidance on how to make a speaker cable to wire up 2x12s or 4x10s from the BJ’s speaker output. What ohm rating for the speakers would I be looking at for each configuration and how should it be wired? Does anyone sell a pre-made 212 or 410 speaker cable? Would taking a speaker cable from a Deville 212 or 410 work? I have looked at pictures of the back of Deville 410 and it looks like Fender wires them in series using a 13.5″ speaker cable that then has the right side going to one top speaker and the left side going to the other top speaker. Then there are jumpers from there to the others speakers.

    Thanks Bill!

  32. Wes says:

    So far the 12F150 has risen to the top of the list (the 50w); but with several other cabinets out there for the Blues Jr. I was wondering if you had ever managed to evaluate any single 15″ configurations and, if so, had a recommendation. Genre would be clean, surf & a little country. Thanks sir!

    • bill says:

      Sorry, I haven’t evaluated 15s. I’ll have to run the BJr through the Legend 1518 in my Excelsior one of these days. Thanks for the feedback on the 12F150.

      • Wes says:

        Thanks very much. I’m just between ideas about which cab to get from Carl; I heard your Excelsior comparison with the 1518 (dramatic) and Carl’s HRD-sized cab can be done with a 15″ baffle. So I’ll check back; muchas gracias!
        :)

  33. bbqbrisket says:

    Bill..
    I read the following post on another web site. Is there any validity to this for the BJ?

    “I bought the Swamp Thang in October with the intention of putting it in a combo that I purchased. I loved the tone of the Swamp Thang on their web site, ……..but not knowing much about wattage at the time I really shouldn’t have purchased a 150 watt speaker because the combo was only 40 watts……”

    ????Does this hold water?

    • bill says:

      Nope. The wattage has nothing to do with the tone. It’s just the amount of power you can pour into the thing until the voice coil overheats and melts. Even speaker cone breakup has nothing to do with watts. It’s a function of the thinness or thickness of the paper cone.

      The first number to look at is sensitivity–the dB produced at one meter’s distance, driven by one watt. The second is the manufacturer’s rating for late, medium, or early breakup. The breakup is engineered into the cone by the thickness, number of pleats, doping, cone depth and angle, etc. You can find early-breakup speakers (not my thing, typically) with plenty of power handling, which ensures that you won’t drive the voice coil into the limit stops.

      If you play with full-on distortion, be sure to have double the power handling as your amp’s output, because distortion is essentially square waves, and a square wave packs nearly twice as much power as a sine wave.

      The Swamp Thang, incidentally, is one of Eminence’s loudest, most sensitive speakers, and also the most resistant to breakup.

  34. bbqbrisket says:

    Thank you bill…..just bought a few item from you.

  35. H says:

    Hi Bill. Have you an opinion on the Jensen P12Q? Feedback would be much appreciated.

  36. bbqbrisket says:

    Hey Bill,
    Just replaced my BJr II series with a Swamp Thang.
    I find that it’s way too loud. Very solid on the bass but too spiky on the higher end.
    In your opinion, Is there a better alternative for a smoother, rounder, surfy/jazzier output that does not
    have that loudness?
    thanks

    • bill says:

      You could give the Cannabis Rex a try. It can’t make a harsh note, and it’s not as loud as the Swamp Thang. The reason I use the ST in the shop as my test speaker is that I want to hear every little detail from the amp, not the speaker. The efficiency and slow breakup work well for that or for un-mic’d performances when you’ve got to get the most out of it.

  37. bbqbrisket says:

    Ok,I will definitely check that out.
    Have you been able to check out either Weber’s AlNiCo California 40oz, 60 Watts or the
    Ceramic California 60oz Ceramic, 80 Watts.

    thanks again

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