fender blues jr.

[travelin travis]

is $175 a good price for a blues junior? it needs new power tubes but they are only $15-25. if i buy it, i'm gonna put trim's in it for an adjustable bias. it's the one with the green pc board. anyone own one?

 

[KKM1]

thats a pretty good price.

check out the fender forums for tons of info on the BJr.

http://www.fenderforum.com/

 

[Nick The Man]

is $175 a good price for a blues junior? it needs new power tubes but they are only $15-25. if i buy it, i'm gonna put trim's in it for an adjustable bias. it's the one with the green pc board. anyone own one?

whoa ..that is an excellent price


I've been looking for one of these, I have heard many good things, I would say BUY IT!

 

[bongolation]

is $175 a good price for a blues junior? it needs new power tubes but they are only $15-25. if i buy it, i'm gonna put trim's in it for an adjustable bias. it's the one with the green pc board. anyone own one?

That's about all I'd pay for a greenboard. I'm sure people often pay more, though.

As you probably know, the greenboards are substantially less desirable due to multiple problems with the reverb circuit, which Fender eventually redesigned after myself and many others raised a huge stink over the uncorrected problems on the FDP a few years ago -- though FMIC staunchly denied the problem existed.

Bill Machrone came up with some retrofixes for a couple of the problems, but if you're talking about installing bias adjustments, then it sounds like you're already familiar with his site, as he explains how to do that, too. The stock fixed bias setting on the Blues Junior is very hot, though I have never understood why. As mentioned, there are other design problems with the original Blues Junior, and maybe this is just another one...but why didn't they change it on the whiteboard?

I'm not 100% on the same page with Bill about some of his mods, but for the most part, they are improvements.

 

[travelin travis]

That's about all I'd pay for a greenboard. I'm sure people often pay more, though.

As you probably know, the greenboards are substantially less desirable due to multiple problems with the reverb circuit, which Fender eventually redesigned after myself and many others raised a huge stink over the uncorrected problems on the FDP a few years ago -- though FMIC staunchly denied the problem existed.

Bill Machrone came up with some retrofixes for a couple of the problems, but if you're talking about installing bias adjustments, then it sounds like you're already familiar with his site, as he explains how to do that, too. The stock fixed bias setting on the Blues Junior is very hot, though I have never understood why. As mentioned, there are other design problems with the original Blues Junior, and maybe this is just another one...but why didn't they change it on the whiteboard?

I'm not 100% on the same page with Bill about some of his mods, but for the most part, they are improvements.

I don't know why fender would run this amp so hot. Maybe they're trying to sell tubes? Not likely. As far as the reverb, the fix looks pretty simple. One more thing, the friend that is selling the amp upgraded the reverb tank out of ignorance (not downing him) and the speaker to an eminence red fang (i think). Basically I just want the amp to learn about tube amps and to try out some mods and tube swaps. I just ordered a book that a co worker reccomended, Dave Funk - The Tube Amp WorkBook.

 

[bongolation]

I don't know why fender would run this amp so hot. Maybe they're trying to sell tubes? Not likely. As far as the reverb, the fix looks pretty simple. One more thing, the friend that is selling the amp upgraded the reverb tank out of ignorance (not downing him) and the speaker to an eminence red fang (i think). Basically I just want the amp to learn about tube amps and to try out some mods and tube swaps.

See if you can get the proper reverb pan back from him and put it in. It really won't work properly with a different unit without fiddling the circuit. The original pan is fine as a unit if you don't get noise from it from the little transformers inside shifting around. I nearly went crazy trying to find that noise before catching it. A drop of crazy glue will secure them if they're moving around.

This is the same unit Fender uses in some other amps and it sounds much stronger in them, so -- as we already know -- the problem is in the circuit, not the pan.

Bill's fix for the reverb is an improvement, but the whiteboard is more of a complete redesign, moving to a lower-noise 4560 OpAmp and changing the placement of some components. Be sure to do the reverb feedback shielding fix, too, because the reverb circuit feedback on a greenboard can get really bad if it's turned up.

I got a Blues Junior for approximately the same reason you did, but I would advise to take it easy on the tube swapping, and the PCB tube sockets tend to get pretty loose pretty fast and they're a nuisance to replace. The backs aren't accessible, so you can't just tweak the backs of the sockets to make them tight again.

V1 is about the only really worthwhile tube to swap out anyway, possibly V2, which is the preamp recovery tube. I'd keep the stock tube (a Sovtek 12AX7WA) in the phase inverter (V3). If you want to screw around with the sound, you'll get your most apparent results in V1...but don't expect miracles. I think I have a Mullard in mine or possibly a JJ ECC83S...I can't remember. A vintage Mullard (or the essentially identical Dutch Amperex) is a real cure-all for preamps.

Try to stay with shortplates in the preamp tubes and use caution. A very competent tech I know of discovered that the increased current draw on the Sovtek 12AX7LPS heater circuits was such that it consistently killed Blues Junior PTs if he replaced V1, V2 & V3 (all the 12AX7*s) with the 12AX7LPS! Yipes! The 12AX7LPS is debatably the finest 12AX7* made today, but it's a very longplate design that I regard as unsuitable for combo amps due to longplate vibration sensitivity -- it's great in separate bass heads, though.

If you want a really nasty tone, try one of those ubiquitous Chinese 12AX7As that came as the OEM tube in nearly every amp in the early '90s. Not a distinguished tube, but instant dirt if you want it in V1.

 

[travelin travis]

See if you can get the proper reverb pan back from him and put it in. It really won't work properly with a different unit without fiddling the circuit. The original pan is fine as a unit if you don't get noise from it from the little transformers inside shifting around. I nearly went crazy trying to find that noise before catching it. A drop of crazy glue will secure them if they're moving around.

This is the same unit Fender uses in some other amps and it sounds much stronger in them, so -- as we already know -- the problem is in the circuit, not the pan.

Bill's fix for the reverb is an improvement, but the whiteboard is more of a complete redesign, moving to a lower-noise 4560 OpAmp and changing the placement of some components. Be sure to do the reverb feedback shielding fix, too, because the reverb circuit feedback on a greenboard can get really bad if it's turned up.

I got a Blues Junior for approximately the same reason you did, but I would advise to take it easy on the tube swapping, and the PCB tube sockets tend to get pretty loose pretty fast and they're a nuisance to replace. The backs aren't accessible, so you can't just tweak the backs of the sockets to make them tight again.

V1 is about the only really worthwhile tube to swap out anyway, possibly V2, which is the preamp recovery tube. I'd keep the stock tube (a Sovtek 12AX7WA) in the phase inverter (V3). If you want to screw around with the sound, you'll get your most apparent results in V1...but don't expect miracles. I think I have a Mullard in mine or possibly a JJ ECC83S...I can't remember. A vintage Mullard (or the essentially identical Dutch Amperex) is a real cure-all for preamps.

Try to stay with shortplates in the preamp tubes and use caution. A very competent tech I know of discovered that the increased current draw on the Sovtek 12AX7LPS heater circuits was such that it consistently killed Blues Junior PTs if he replaced V1, V2 & V3 (all the 12AX7*s) with the 12AX7LPS! Yipes! The 12AX7LPS is debatably the finest 12AX7* made today, but it's a very longplate design that I regard as unsuitable for combo amps due to longplate vibration sensitivity -- it's great in separate bass heads, though.

If you want a really nasty tone, try one of those ubiquitous Chinese 12AX7As that came as the OEM tube in nearly every amp in the early '90s. Not a distinguished tube, but instant dirt if you want it in V1.

I will be looking to get more of a marshall tone out of this amp. I found this page while looking up mods: http://mhuss.com/BluesJr/page3.html
There's a couple of sound clips at the bottom of the page. It sounds like a pretty drastic attitude change for the Blues Jr. for not much effort and money.

It would probably be a major pain in the ass but I wonder if it would be worth gutting this amp and changing out the pcb for a turret board. At the moment I don't know much about tube amps so I'll look into it more after I get enough tube amp theory under my belt to even think about such a thing. Thanks for the info Bongolation.

One more thing. I saw that Epiphone has a couple of little tube amps out now. One of em is a little 5 watter for $120. It looks like it would probably make a good little amp to mess around with too.

 

[ggunn]

I will be looking to get more of a marshall tone out of this amp.

Well, although the Junior breaks up very nicely, even "as is", I don't believe that any mod will get you the thump and thud out of it that a Marshall with a closed back cabinet generates.

 

[travelin travis]

Well, although the Junior breaks up very nicely, even "as is", I don't believe that any mod will get you the thump and thud out of it that a Marshall with a closed back cabinet generates.

i plan to get a 212 avatar cab at some point. i hear that the blues jr. sounds alot better thru a 212 cab.

 

[ggunn]

i plan to get a 212 avatar cab at some point. i hear that the blues jr. sounds alot better thru a 212 cab.

That is probably true, though I am told that the EL84's can't produce the low end that EL34's can. It's an idea, though; maybe I'll see what mine can do into my Marshall 4-12 cab.

 

[Nick The Man]

That is probably true, though I am told that the EL84's can't produce the low end that EL34's can. It's an idea, though; maybe I'll see what mine can do into my Marshall 4-12 cab.

listen to him he got to see stevie ray vaughan (LUCKY)


did mention hes from austin texas

 

[travelin travis]

That is probably true, though I am told that the EL84's can't produce the low end that EL34's can. It's an idea, though; maybe I'll see what mine can do into my Marshall 4-12 cab.

i'd like to know how that works out. maybe a sound clip?

 

[travelin travis]

I just got the Blues Junior this weekend. I originally thought that my friend had changed the reverb tank as an ill informed upgrade but I found out that the original reverb tank was broke so he put in a new one. The new tank is a 3 spring and the original was a 2 spring. I'm hoping that this does'nt cause any problems.

The replacement speaker is a Eminence Legend but there is'nt a model # that I can see on the speaker any where. My friend said it is a Legend Vintage model. Apparently it was removed from another amp because it still has the connectors from the old amp soldered on to the speaker terminals.

The Tube Amp Workbook, which was recommended to me, seems to be over my head. It does'nt go into enough detail about basic tube amp theory for the beginner, imho. Alot of tube amp terminology seems to just "appear" without any prior explanation of what the terminology means. The book starts off talking about some tube amp circuits before any explanation is even given about basic electronics theory and components. I think I'll start looking for a more beginner orientated book.

I hate having this amp sitting around unplayable but I really want to learn about tube amps and get it going myself. I just hope it's not sitting around too long while I'm learning.

 

[gusfinley]

The Tube Amp Workbook, which was recommended to me, seems to be over my head. It does'nt go into enough detail about basic tube amp theory for the beginner, imho. Alot of tube amp terminology seems to just "appear" without any prior explanation of what the terminology means. The book starts off talking about some tube amp circuits before any explanation is even given about basic electronics theory and components. I think I'll start looking for a more beginner orientated book.

If you need help on terminology, then let us give you a hand. I'd bet we could create a forum tube amp book with all the knowledge that is avaibale around here.

I have had a hard time finding a good tube book myslef. I did rather enjoy Dan Torres' Tube amp book, it was simple to understand and had a lot of really good info about mods and such, and there is an amp project in the final chapter. (of course I am studying electrical engineering so terminology was never a problem). My main problem thought is that most of the book I have found have been either a collection of old schematics, with not real information on the hows and whys each amp is different or really over the top things that you could do with tube amps. I have enjoyed the Radiotron Designers handbook - from a design, theory and operation perspective - but it is NOT light reading.

 

[ggunn]

The Tube Amp Workbook, which was recommended to me, seems to be over my head. It does'nt go into enough detail about basic tube amp theory for the beginner, imho. Alot of tube amp terminology seems to just "appear" without any prior explanation of what the terminology means. The book starts off talking about some tube amp circuits before any explanation is even given about basic electronics theory and components. I think I'll start looking for a more beginner orientated book.

I hate having this amp sitting around unplayable but I really want to learn about tube amps and get it going myself. I just hope it's not sitting around too long while I'm learning.

This was the first book on tubes that I bought:
http://www.londonpower.com/books/tut.htm

It was very informative and basic. The rest of the books in the series look good, too, but I only have seen the first one.

Any of these books will assume an understanding of basic electronics as to what resistors, capacitors, and inductors do, how Ohm's Law works, DC versus AC concepts, etc. If you've not studied that stuff yet, you may need to do some general reading first.

RULE #1FOR WORKING ON TUBE AMPS: Find the high voltage power supply nodes and discharge them before poking around in the circuitry. The filter caps can retain potentially lethal voltages on these nodes for a long time after the amplifier is turned off and disconnected from power. NEVER work on an amp that is plugged in and powered up unless it is absolutely necessary, and then take extreme caution to avoid contacting these points in the circuit. This is a very dangerous lesson to learn the hard way.

Also, the Blues Jr. (or any other modern mass produced amp) may not be your best starter project, as these amps use PCB (printed circuit board) technology to shuttle the signal around. PCB designs can be difficult to mod; a better choice would be an older amp that uses PTP (point to point) wiring. My first was an old Supro clone of a Fender Champ that I bought at a yard sale for twenty bucks.

Have fun!

 

[travelin travis]

would the electro-harmonix el84 eh pair be good replacements for my green board blues junior? i was looking for replacements at www.tubedepot.com and saw these. the description says that they tend to pull more current. i don't really know what effect that would have on my amp.