Getting a cleaner, louder Blues Junior

[papuanewjimmy]

First off, I'll preface this by saying this is my first tube amp, so I'm new to this whole game. I've been playing guitar for about 10 years (just turned 24), so yeah, I'm a late bloomer in the tube world. Its a lot easier to sell a goofball high school kid a 100w amp than a 15w amp when the pricetag is the same, regardless of the difference in sound!

Anyways, I recently realized the error in my ways, repented, renounced my solid state roots, washed in the water of the river- well, you get the idea... I bought a Fender Blues Junior. I'm SO unbelievably stoked. It sounds amazing. I have only one gripe- I'd like it to stay clean at higher volumes. I believe I'll soon be referring to this as "breaking up later" or "having more headroom"? I can't yet describe to you what the sound is that I'm going for, but right now I like the way it responds with the volume at about 2.5-3 and the master at about 6-9... just BARELY getting dirty when you pound a chord. What I'm going for is something like the guitar on Tom Waits' Mule Variations... think "House Where Nobody Lives" or "Come On Up to the House."

So from what I gather I can change the tubes and speakers easily, but what recommendations do you folks have in either or these categories, given my goals? I've heard changing the 12AX7s to 12AT7s helps? And what brand/wattage speaker should I be looking for? I realize I could just buy a higher wattage amp, but funds and space are limited, and I'm really happy with the Jr for the most part. I'm no idiot, but I have little to no experience with circuits and electronics, so I'm mildly wary of trying some of Bill Machrone's mods. Has anyone tried this one (not Bill's, but I found it through his site): http://home.comcast.net./~machrone/bjr/bjgunther.htm

Thanks so much,

Jimmy

[Don Moose]

Here's the thing, Jim - a loud clean requires more power. Distortion is what happens when your amp runs out watts before it runs out of gain.

Here's the sick thing - doubling the watts only gets you 3dB more loud, which is supposedly barely noticeable. Get a speaker that's 6dB more efficient and bingo, you've gone from the loud a 15W amp will make with the original speaker to the loud a 60W amp could do with that same original part.

A more efficient speaker would be your first step - more loud for the same watts. I don't get involved in questions of taste, though, so have no suggestions.

[bob p]

IMO the first thing to consider if you want a little amp to sound like a bigger amp is to play it through a bigger amp's speakers.

Little inexpensive amps invariably tend to have less expensive speakers that have a lower power handling capacity than big amps have. As a result the distorted sound from your little amp is likely the result of a combination of amplifier distortion and speaker distortion. Before considering any mods to the amp's electronics, I would consider trying out the amp with a clean sounding speaker that's capable of handling far more power than your amp is capable of delivering. In a case like that the amplifier will be giving you distortion, not the speaker. That may be all that you need.

That's a place to start, anyway.

[papuanewjimmy]

Thanks for the replies guys, that was just what I needed. Don, you certainly are wise- I hate seeing people argue over matters of pure taste!

So my question now is what specification are we speaking of when we say that one speaker is more efficient than another? Is it simply that one is rated for a higher wattage, or is there something else to take into account? Bob, when you say "far more," can you recommend a wattage range I should look into?

For others potentially interested in this topic, I didn't complete ALL of my homework before my initial post. While I had heard that exchanging tubes for different members of the same "tube family," I found this page of Bill's Blues Junior website immediately after posting. Sorry about that.

http://home.comcast.net./~machrone/bjr/bjtubes.htm

One more speaker question- aside from just buying speakers until I find one I like, are there places I can hear side-by-side comparisons of speakers played through the same amp? I'd also like to learn a little bit more about the differences between speakers, like what is the audible difference between AlNiCo and ceramic magnets (and why does (/doesn't?) it exist. I've only found an old Guitar Player magazine review of about a dozen speakers, and it wasn't all that helpful.

Thanks again for your input, Bob and Don. Like I said, that was exactly the sort of help I was looking for.

[bob p]

Speakers are the kind of thing that are very much a matter of personal taste. If you ask 1000 people for advice on what speaker would go well with your amp, you might get 1000 different answers.

The most common speakers used in guitar amps are probably Celestions, Eminence, and Jensen. Other good names to consider are Weber and Electro-Voice. You can find speaker specifications at each of the manufacturer's web sites and compare some numbers on-paper to get an idea about efficiency. I don't think you'll get much useful info about tone.

Within each line of speakers you'll find models that are prone to distort and models that are less prone to distort. As a rule of thumb higher power ratings suggest that the speaker will break-up later. Weber is the only manufacturer I know of who rates their speakers in terms of early/late break-up. If you want cleaner tone, that means later break-up.

For my purposes, I like to use a speaker that stays clean all of the time, and I like to get distortion out of my amplifier. I like to use EVM speakers rated at 200W to 400W for this reason, even with my little amps. They stay clean. Another valid approach is to get speaker distortion as part of your sound, but if you want a cleaner sounding amp that might not work for you.

If I were in your shoes I would disconnect the internal speaker in my BJ and hook up a bunch of different extension cabinets to see what sounds best. Don't expect a quick answer. Some people spend years searching for the right speaker and amp combination.

[Satamax]

Jymmy, the hard bit gonna be to find a more efficient speaker. The gold label and special design fender speakers are made by eminence. And they usualy make pretty efficient speakers. Efficiency is noted in DB I'd think the emmies in fenders are around 98/99db, that's just my guess! So if you want 6db more you'll have to go for 104/106db! That starting to be big!

Red thang, wizzard and so on for the high efficiency from eminence.

http://www.eminence.com/guitar.asp?speaker_size=12

You can check this on the celestion's site, thought there isn't a clear chart and you'll have to check each speaker individualy for efficiency rating.

http://professional.celestion.com/gu...tone/index.asp

I seem to remember that there was a 106db somewhere around, thought, i can't remember if it was celestion or jensen.

Jensen doesn't seem that efficient after all there's the chart.

http://www.jensenvintage.com/tonechart.pdf But again, you'll have to check each individual speaker for proper ratings.

Weber doesn't even lists efficiency!

http://www.tedweber.com/

[Shark_Sandwich]

No, Weber doesn't list efficiency, but give him a call or email and he'll give you good advice.

FWIW - I bought a Weber Blue Dog (Celestion Blue clone) about 6 months ago, and I love it. At Ted Weber's suggestion, I upped the size of the magnet (ceramic) in order to increase sensitivity. It is a much louder speaker than I was using. I think it's louder than a Celestion Vintage 30 that I tried out. I'm using a very old PA amplifier for guitar, probably running at 15-20W, and it's plenty loud enough to play medium sized bars with quite a bit of clean headroom.

Give Ted Weber a call or email - he knows his stuff, his speakers sound great, and they are relatively inexpensive.

[JJGross]

I was looking to get a better distortion sound out of my HRDx and found in my amp an 80s era Carvin 100w British Series speaker was the ticket. With a power tube swap from 6L6GCs to EL84s and old manufacture pres my clean is still Fender, but driven I'm leaning way into the Marshall/Vox realm than the fizzy stock Fender overdrive. The old Carvin British speaks can be found on ebay or CL around $35. You might not like the sound of them, but I'm not changing anything in my amp now.

For 'never break up' speakers you might want to check out some JBLs. I have a pair of them in my 70s Twin. Crystal clean at all levels, they just don't break up until you're hurting yourself. That's not making a joke with a 135w Silverface Twin Reverb loaded with a pair of JBLs.

Cheers,
- JJ

[bob p]

Originally Posted by JJGross

For 'never break up' speakers you might want to check out some JBLs. I have a pair of them in my 70s Twin. Crystal clean at all levels, they just don't break up until you're hurting yourself. That's not making a joke with a 135w Silverface Twin Reverb loaded with a pair of JBLs.

are you talking about "hurting yourself" when you play that amp loud, or when you try to lift it???

JBL "D" series speakers are GREAT for loud and clean, but they're pretty damned expensive pieces of vintage gear. Probably a LOT more money than one would want to spend for a Blues Junior extension cabinet. I think that Ted makes a Weber California that's small enough to fit into the BJ cabinet. That might be a reasonable solution, Jimmy.

[stokes]

All good advice on the speakers,just wanted to chime in with a vote of confidence for Ted Weber,he is one of the best.If you email him and tell him what you are looking for he will give some solid advice and recomendations,he has hit the nail on the head at least a half dozen times for me or others I was doing work for.I believe he can match any speaker out there.

[WholeToneMusic]

I have a Blues Jr. on the test bench that had a custom wood ring made for it to fit the Weber Sig 10 and it sounded good, I did the Bill M tone stack mod and this amp sounds dynamite. The Sig 12 may be worth looking into. I hear that it doesn't sound as good as the 10 though.

[WholeToneMusic]

Also I forgot to mention that I changed out the Reverb tank to a Ruby, Just in doing that alone the amp sounded better.

When Fender designed that circuit they biased the tubes very hot and the amp is as loud as you want to get it without replacing EL84's every other day, What I would suggest is to increase the 22k bias divider resistor(R52 on the creme board) to 30k, The amp will run cooler and it sounds cleaner, better for Jazz However it will have less power.

I have tried this with a customers amp and he was very happy with it. This allows you to use other EL84 tubes that normally wouldn't hold up with the way the amp was originally biased. Your best bet is to try a higher dB speaker which was recommended earlier in the thread. Another option is to get the Mojo Blues Jr Output transformer upgrade which is more efficient than the original and have it put in, It also sounds better than the original transformer. Check the Bill M mod page to get more ideas for your Blues Jr.

[ctcpete]

I have a 2003 Blues Junior with the original Jensen speaker and just finished the following Bill M mods about a week ago: Basic kit, cream board Presence control,High-voltage preamp mod, Switchcraft all-metal Input Jack, clean boost module, and power supply stiffening. If you are not comfortable with soldering and electro mechanical work, you may want to have these mods done by a tech. I was a field engineer in the printing industry for many years so I was comfortable doing them. I am now trying a refurb and blackface conversion on my 74 Silverface Twin Reverb.
I do have a problem after doing the Blues Junior mods with a hum that occurs at higher volumes with my single coil pickup G&L guitar (not evident with a humbucker equipped guitar). I believe the mods added some extra gain. The hum was probably there all along but I didn't notice it before as I had been playing it at lower volumes. Any advise on controlling single coil hum on a Blues Junior? I have tried twisting the like color xformer wires together. Would the upgraded xformer help out maybe? I am waiting for a reply from Bill. I've heard he has a 6 month backlog of amps at this time. Other than the hum I'm very happy with the mods.

Pete

[ncboy654]

if you do all the mods ctcpete did, you can replace the 50k master volume with 100k or maybe 250k for a little more output, but as other people have said, there's only so much clean to get from a 15w amp.

[WholeToneMusic]

Hello Pete,

The mod makes it sound much more pleasant to the ear. The Blues Jr is very suseptible to outside interferance around the first gain stage. If you even wave your hand around v1 inside the chassis you will get noise. I would suspect that it would be a lead dress issue with the grid wires too close in proximity to other wires, and the 12ax7 just amplifies that even more. You could try using a 5751 preamp tube in V1 which has an amplification factor of 70 opposed to the 12AX7 which is 100. If that doesn't work you could try a 12AT7 which has an amplification factor of 60.

If you have the chassis open and are comfortable with working on a live amp crank it all the knobs all the way up and use a chopstick or sharpie or any other non conductive instrument to move the wires around a bit to see if the hum disapears. If you cut any of the zip ties and re-tied them make sure all the wires are in the same bunch. I usually take a few digital photos before I disassemble the PCB.

Best of luck

[ctcpete]

Whole tone, thanks for the reply. The different tube options sound interesting.
I have tried moving the xformer wires around etc while powered up with no luck (I am comfortable with this stuff, I have a long tech background in the printing industry but am a tube amp novice). In the instructions, Bill recommended re routing the transformer leads so the like colors where wire tied together and routed well off the surface of the pcb. Originally they where all wrapped around each other coming off the xformer. I was sure to put each wire back to it's original terminal on the pcb (labeled them before removing).
Would I be able to better shield these wires somehow? Maybe shrink wrap?
Thanks again for the great information.

Regards, Pete

[Direwolf]

You could try the Eminence Red White and Blues speaker. I believe they recommend it as a replacement for the BJr. Sensitivity is 102db which is about 3-4db higher than the original. It's rated at 120 watts so you probably won't get any speaker distortion with it. I have one in a 5E3 build and love it. I also have a BJr that I did some of the BillM mods on. Tone stack, bias and added a cap in the power rail. I love the tone I get from it. I use the 5E3 and BJr in tandem and get a very unique tone, one I can call my own. I've also hooked the BJr up to the RW&B in the 5E3 and I really like the way it sounds. I may just replace the stock speaker in the BJr with another RW&B.

[Robmosis]

Have you simply tried to max your master volume and start you preamp volume low and turn it up as needed. This usually helps for headroom. When you max your master you are using your power tubes which break up a lot later than your preamp tubes. I you reverse this then your preamp tubes are made to break up early.
Also Have you tried maybe a 12AY7 in you v1 position. This has a lower gain of about 60% if I am correct, compared to the 100% of the 12AX7.
A Lot of people doen't realize but when a lot of classic fenders like Bassmans, Champs, and such first came out they were built around the 12AY7 for more headroom and later breakup. People switched to the 12AX7 when the supplies of 12AY7's started to dry up. Eventually changing the sound people expected from these classic fenders.
Speaker efficiency is another big point also as stated earlier. Other than the stuff people have told you You might have to consider that you just have the wrong tube amp. It happens to most who first convert to tube amp. Myself included. I now use a Vox AC30CC2 and it has massive amounts of clean headroom and fantastic drive. Not to mention the unbelievable Vox tone.
Best amp I have had with just a gright cap mod in the tb channel and tubes.
I will change speakers next.

[thunderfoot]

I've owned several modern tube amps(solid state rectifiers with pc board mounted tubes and pots),and I'm telling you,it's one thing to replace the speaker,but if you ever get close enough to a silverface pro reverb,or any other vintage tube amp in the less than 50 watt range,you're gonna be tradin' in the junior!!!! I own a 1999 Blues Junior,jj pre amp tubes,torres bass boost mod,and swapped the speaker for a celestion v30-this amp sounds way bigger than it looks.I've tried it through crate extension cab with a pair of celestion 80's,with my '76 twin with a pair of red coat gov'ners,and in my '73 pro with a pair of v30's.The pro is what sold me for the junior.They're rated at 60 watts each,giving a nice break-up almost perfectly in time with the overdrive of the tubes.The mid spike they are notorious for helps the junior in the low-mid range to the point of vibrating the cabinet enough to rattle!!!! The gov'ners are softer in the middle,which is great for the twin,and the pro reverb is gutsier and darker with the v30's.Just for a giggle,I hooked the junior up to the stock speakers outta the twin....not even funny-v30 all the way( yes,I know the junior is an 8 ohm load,and the pro and twin are 4 ohms with both speakers,but I only used one of each-the crate cab was 4-8-16 ohm selectable)...I have a stock junior to compare the modded one to,and I hope I never hear another stock junior....Like the others say,it's your choice-if you're playing an articulate style of music(blues,jazz,older country),you want that big,fat,but clean note sound.If you're playin' rock,you don't always want the single notes to stick out,more likely,the transition from note to note will be smoother and more important than the note-I can't believe I just said that.
So,it's not just the mod's,speakers,guitar,cord,pedals(if any),or amp that you wanna consider.The musical style,the amount of time you play through the amp,how much you want to spend-very big factors ..
As i said,I had to work my way through some amps to get the sound I wanted...Tube Works Tube Driver,Crate VC50,Crate Vc30,Fender Blues Deville,Blues Junior,Hot Rod Deville,Blues Deluxe,Princeton Reverb II,then eventually my 73 pro,then 76 twin...The junior is very cool,light,and wicked hot with the new speaker and mods,but you hafta walk that path yourself to find what you like.BTW,the v30's need a lotta break in time-warehouse speakers has a clone for half the price.....Good luck

[boyt_bpc]

I tried the JBL D120F from my silverface Twin in my Blues Junior and it was amazing. I'm going to order Webers California speaker, which is very similar.

[roseblood11]

Hi,

BillM shows a clean boost module on his site, but unfortunately, he doesn´t explain it. If I´d live next door to him, I´d let him do the mod, but I live in Germany , so I gotta find out how to do it on my own.

Can anybody explain, how exactly this mod works? I think I understand the circuit itself, it looks like a simple Booster based on one BS170, just like the SHO. But how does he connect that circuit (and a switch) to the amp?

http://billmaudio.com/wp/?page_id=105

regards, Sue

[WholeToneMusic]

The Bill M mods page Clean Boost is adding an extra Adjustable gain stage for an extra +9 dB. You can get a boost also by bypassing the tone controls (the adjustable EQ can attenuate the circuit by -30 dB or so. These insertion losses are usually compensated for by adding extra gain stages. There are areas in most common amplifiers that can cause dB loss in the circuit. Such as on an amplifier which has a vibrato, reverb or a Negative feedback loop. I always disconnect the Vibrato and or the feedback loop to open up the amplifiers hidden potential. By doing the above mods (disconnect the - feedback loop and the virbrato circuit.) to a Blackface Super Reverb along with adding a boost you can get the amp sounding close to the volumes of a Twin that has the same insertion losses.

[WholeToneMusic]

Originally Posted by ctcpete

Whole tone, thanks for the reply. The different tube options sound interesting.
I have tried moving the xformer wires around etc while powered up with no luck (I am comfortable with this stuff, I have a long tech background in the printing industry but am a tube amp novice). In the instructions, Bill recommended re routing the transformer leads so the like colors where wire tied together and routed well off the surface of the pcb. Originally they where all wrapped around each other coming off the xformer. I was sure to put each wire back to it's original terminal on the pcb (labeled them before removing).
Would I be able to better shield these wires somehow? Maybe shrink wrap?
Thanks again for the great information.

Regards, Pete

Shrink wrap won't work very well unless it has a metal casing around it. I would move the wires around with a chopstick with the amp live
to see where they sound the quietest and let the rest there. Some heavy duty foil wrapped around the wires could do the trick to help further isolate the wires.

[roseblood11]

Hi,

Originally Posted by WholeToneMusic

I always disconnect (...) the feedback loop to open up the amplifiers hidden potential.

It´s possible to just open the negative feedback loop? Doesn´t that increase the output impedance? The amp will still work with the same speaker at the same speaker jack/impedance setting as before?

I´m asking because my Carvin Vintage 33 sounds way too tight and I thought of adding a pot (~1M Ohm) in series with the serial resistor (R33) in the neg. feedback loop. Here´s the schematics:

http://www.carvinmuseum.com/pdf/amps/VINTAGE33.pdf


~~Sue~~

[Robert M. Martinelli]

Originally Posted by roseblood11

Hi,



It´s possible to just open the negative feedback loop? Doesn´t that increase the output impedance? The amp will still work with the same speaker at the same speaker jack/impedance setting as before?

I´m asking because my Carvin Vintage 33 sounds way too tight and I thought of adding a pot (~1M Ohm) in series with the serial resistor (R33) in the neg. feedback loop. Here´s the schematics:

http://www.carvinmuseum.com/pdf/amps/VINTAGE33.pdf


~~Sue~~

The possibility of opening the NFB has little to do with the output impedance, it's a stability-related matter instead.

If you look at the schematic you'll see that your amp's NFB ( neglecting C34 which, if I read the schematic right, is not fitted ) is a fixed voltage divider, formed by R33 and R32 ( Ok....in parallel with R22 and C47 but let's neglect them for a moment to make things easier ), and the resistance to GND of R32-R33 is 242 KOhm. This means that they're negligible as a load, because they're paralleled to the speakers, so the parallel load can always be approximated to the speakers' impedance.

The purpose of an NFB is twofold, it adds stability at the expense of gain, and it can be also used to shape the amp's tonal range. Removing it could bring some amp to oscillate; in your case I would say it could be worth to add an RC NFB, using a pot to find that "sweet spot" you're after. Once you have achieved the tone you want, you could sub the NFB pot with a fixed resistor to "freeze" the "correct" NFB setting.

HTH

Best regards

Bob

[WholeToneMusic]

Originally Posted by roseblood11

Hi,



It´s possible to just open the negative feedback loop? Doesn´t that increase the output impedance? The amp will still work with the same speaker at the same speaker jack/impedance setting as before?

I´m asking because my Carvin Vintage 33 sounds way too tight and I thought of adding a pot (~1M Ohm) in series with the serial resistor (R33) in the neg. feedback loop. Here´s the schematics:

http://www.carvinmuseum.com/pdf/amps/VINTAGE33.pdf


~~Sue~~

The negative feedback loops feeds some of the signal from the secondary OT back into the amplifiers Phase Inverter stage in reverse polarity. It does not change your output impedance. You can disconnect it most of the time without issues. If you disconnect it and the amp squeals then reverse the primary ot wires on the power tubes. That should take care of the oscillation. You could replace R33(220k) with a 250K 2 watt mil spec pot for added protection and extended sweep. Tightness in an amp is usually in the power supply. The amps choice of rectification and amount of filtering can determine the amps stiffness. The vintage 33 uses a fullwave rectifier using 4 1N4007 solid state rectifiers and a first filtering cap of 44 uF's. (two 22 uF's in parallel) I would suggest changing out the 1N4007's for HEXFRED diodes. This will give you a softer recovery.

[jrfrond]

After repairing and modding countless BJ's, it has occured to me that retrofitting the amp with 6V6's is a reality that can be accomplished with some work. 6V6's have it WAY over EL84's in the "clean" department, as is usually the case with beam tetrodes vs. power pentodes in most guitar amps. I haven't crunched any numbers for current draw, but there IS a possibility that the PT would need to be upgraded. The stock BJ PT is barely-capable of delivering the needed current as it is. This is due to the puny design of the PT to use as little copper as possible, and using a full-wave bridge rectifier to maximize available B+ voltage. The VA rating, even though I cannot find the specs on it, is pitifully small, as I have replaced lots of these transformers over the years. It wouldn't be impossible to upgrade it to a Deluxe transformer.

The clarity and harder clipping characteristics of 6V6's would really make the BJ sing, more like a DR than anything else.

[papuanewjimmy]

Wow, I had completely forgotten about this post and just randomly came back across it. Well, in case anyone having the same issue finds this thread on a search, here's how I solved my problem: got a bigger amp! Haha, I know, that sounds like a cop-out, but in the end, I was able to get an american made tweed Blues Deluxe for exactly the price I sold the Blues Junior for! The deluxe is a bit beaten up physically, but I actually prefer that look and feel- for example, the stain from a wet drink on top really lends some authenticity! In the end, no matter what speaker I bought, it would have brought the price of the Blues Jr up quite a bit, and as I grad student, I just couldn't really afford to do much experimenting. Overall, I am very happy with the new found headroom I have, and the clean sound of the amp.

Two notes though, for anyone who might be in my exact situation: Of course, as anyone could have guessed, I miss being able to have some real distortion at a tolerable level those for few times I want it. I think there's probably just nothing you can do about this- no tool works for all jobs (if only they made a hammer-duct tape-WD-40 all-in-one!). Maybe buy one of those powerbrakes? However, the other thing I'd point out is that the distortion of the Deluxe sounds different than that of the Blues Jr- and I liked the BJ's better. This could be due to a lot of factors, like speakers, circuit boards, etc, but judging by what I've read and heard, I think it's the power tubes. The Deluxe (I think) has 6L6's; the BJ uses EL84's I think? At any rate, I've often found myself looking up the skirt of amps that have a great distorted sound, and the power tubes are often EL84s or 34s. Then again, could just be a hunch!

FWIW!

Jimmy

[rockon1]

+1 to speaker efficiency! A speaker rated 3 db more sensitive would be like using the same speaker you have and doubling the wattage! Barring finding a speaker to suit your tastes thats more efficient its the simplest way of increasing headroom. Oh and some EL84M's wont hurt either. Bob

[WholeToneMusic]

Good to hear you found an amp that's loud enough for your needs. Most of us have border line tennitis. haha we all would like to save our hearing though.
The amount of and color of distortion is mainly from the amount of gain stages within the amps preamp circuit and the tone stack. The power tubes just amplify the tone that's already present at the phase inverter stage.