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Ok. I have a Fender Blues Jr that started to make a bunch of racket last night a band rehearsal. Off and on static like noise. Kind of like unplugging the guitar and touching the cable end. It's about 8 years old with the original tubes. It also seemed to affect my volume at times. Any clues????? I have a BIG gig comming up and would hate to have to borrow and use a strange amp. Thanks for any input.

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im a tube amp guy myself. and every time mine have acted up its always been the tubes (tube) i pull the caps off and watch the tubes while im playing it. the one thats bad always sparks or flutters. since you bought a fender amp you can usually replace the one tube if you get it from fender. They sound better than the other tubes ive tried anyways. if its the output tubes i would definately do them both together.
When i got my bassman i notced some black marks on the tubes(glass) and when it started poping like your explaning i had a spark arching inside the tube to the glass. when i removed the tube the glass wasnt even seated in the plug.
I have never had a problem with any fender tube amp ever that wasnt as easy as a new tube or two.
Just look at the tubes and the one thats bad will let you know.
Thanks LJ, I'll have to give that a try. I have a '74 super reverb that does the same thing and just passed it off as age, although I had planned on new tubes in the future for it but it'll take a house payment to replace all those. The blues jr only has 5 tubes and I found a place to get all for around $55 bucks. That's a matched set of el-84 power tubes and 3 12 ax7's. Before I spend any scratch I'll heat it up and try your idea. You gotta love that tube sound, right?
Im no guru, but Iv played around with a few tube amps in my time.

Without fail, every single one has had blackened tubes where they have been arcing, but that doesnt mean they are knackered. Sure, in LJs case where the glass had parted company, thats a duffer, but its not a rule.
Its very disheartening to wade in, buy new tubes then find the problem is still there!

Try the obvious things too - clean the pots with switch cleaner, clean the tube seats etc, before you splash out.

I hope LJ is right though and it is just an easy tube swap!

Good luck :o)
it may only be the output tubes. thats the common problem. if the preamp tubes are good just do the output tubes, . in most cases my probvlems have ben output tube related. and one time i had a reverb tube go out on my twin reverb. i believe the output tubes are bigger and there is 2 of them. I went somewhere on the net and found the tube info? or it was in the amp on a scematic of some sort. its probably not both stages.

Dirtfloorcracker said:
Thanks LJ, I'll have to give that a try. I have a '74 super reverb that does the same thing and just passed it off as age, although I had planned on new tubes in the future for it but it'll take a house payment to replace all those. The blues jr only has 5 tubes and I found a place to get all for around $55 bucks. That's a matched set of el-84 power tubes and 3 12 ax7's. Before I spend any scratch I'll heat it up and try your idea. You gotta love that tube sound, right?
again I wouldnt change em if they dont look like theres something wrong with em. see if there 1. sparking, 2. not glowing, 3 not glowing at the same brightness as the matching one next to them. if they look fine you may want to find an amp repair tech to check it out.
And if its under 5 years old it should be under fenders warranty.so find a fender repair shop/or dealer and you should get it done for free.(unless its tubes) they are like brake pads or a battery for your car.born to worn out and not covered.
I pulled the output tubes out last night ansd one has some brown staining on the glass. I'm goning to go ahead and replace them and see what happens. Turns out this amp is fixed bias so the output tubes burn hotter and don't last as long. I used this thing 4 & 5 nights a week for almost 5 years straight without any problems so a little tlc wouldn't hurt it. I found a cool site that is all about the Blues jr. Bilmaudio. The guy mods these little beasts and also sells kits to do it yourself. The mods are more in the line to correct Fenders "mistakes" such as crappy caps and such. He has an adjustable bias kit that I might look into so the little bugger dosen't have to work as hard.

I'm off to .....cough....guitar....cough....center...cough....to get the new tubes. Let ya know how it all turns out. Thanks for the input.
Are those the original power tubes? I would say that with as much playing as you say you do, it would be a wonder if those original power tubes lasted this long. You have done the best thing you could do by taking in all of Billm's info on his site. I did the mods on my blues junior four years ago. It simply brings the amp to life. Now, don't let me steer you wrong. I did the mods for use as a guitar/harmonica amp. It turned out very nicely for both. One thing I would disagree about what has been said above is that I found JJ Tesla tubes to be an improvement in function and tone than the originals. I also like the use of a softer preamp tube. I think I am using a 12au7. Everything collectively makes the Blues Junior a very enhanced amp.
I've heard good things about the JJ's and since GC didn't have what I needed I'll probably be making an order for a set. Billm's site is indeed a warehouse of info and as long as I own a BJr I'll keep his site in my favorites! The tubes are original and I can't believe I've got this far with them. If it aint broke don't fix it, right? The only thing not original with the amp is the speaker. I put in an Eminence Cannibus Rex and it made the amp come to life. Nice speaker if your considering a chnge. What mods did you do and did you do them yourself? I'm pretty good with a soldering iron but a little shy with electronics.

Kenton Kelley said:
Are those the original power tubes? I would say that with as much playing as you say you do, it would be a wonder if those original power tubes lasted this long. You have done the best thing you could do by taking in all of Billm's info on his site. I did the mods on my blues junior four years ago. It simply brings the amp to life. Now, don't let me steer you wrong. I did the mods for use as a guitar/harmonica amp. It turned out very nicely for both. One thing I would disagree about what has been said above is that I found JJ Tesla tubes to be an improvement in function and tone than the originals. I also like the use of a softer preamp tube. I think I am using a 12au7. Everything collectively makes the Blues Junior a very enhanced amp.
Ya, I did all the work myself. I guess you might say I cheated because I am an industrial electrician by trade. I would not let that hinder you from doing it as well. You get it down once and you will always have the skill to use it again. Just make sure you are safe. As I recall, Billm's instruction were pretty much like paint by numbers. If you can glean some electrical knowledge, you can understand what Billm is doing.

Let's see, I did the twin mod, I tamed the hot tubes, I added a presence pot, and I added a switch that would match the use of mics to the input line for my harmonicas. As far as the speaker swap, I did not do it because I have been making my own speaker cabs. If you are good at keeping track of power and ohms ratings, you can make cab cords that will allow you to swap, mix and match speakers for a variety of speaker tone. There is a great book about speaker mixing and matching by a guy from Canada. ( if you are interested in that, let me know and I will get you better details of that book). Speakers and speaker cab mix and matching is only practical when you keep everything to home.

Dirtfloorcracker said:
I've heard good things about the JJ's and since GC didn't have what I needed I'll probably be making an order for a set. Billm's site is indeed a warehouse of info and as long as I own a BJr I'll keep his site in my favorites! The tubes are original and I can't believe I've got this far with them. If it aint broke don't fix it, right? The only thing not original with the amp is the speaker. I put in an Eminence Cannibus Rex and it made the amp come to life. Nice speaker if your considering a chnge. What mods did you do and did you do them yourself? I'm pretty good with a soldering iron but a little shy with electronics.

Kenton Kelley said:
Are those the original power tubes? I would say that with as much playing as you say you do, it would be a wonder if those original power tubes lasted this long. You have done the best thing you could do by taking in all of Billm's info on his site. I did the mods on my blues junior four years ago. It simply brings the amp to life. Now, don't let me steer you wrong. I did the mods for use as a guitar/harmonica amp. It turned out very nicely for both. One thing I would disagree about what has been said above is that I found JJ Tesla tubes to be an improvement in function and tone than the originals. I also like the use of a softer preamp tube. I think I am using a 12au7. Everything collectively makes the Blues Junior a very enhanced amp.
The amp needed new tubes but this didn't solve the problem. After further inspection I found cracked solder joints at the tube sockets. I resoldered them and all is well. Guess I'll have to tear the super reverb apart and check it. I am going to do some of the billm mods. Bias control being #1. Those tubes are just cooking and I want some control over that. Thanks everyone for your input.
BTW....Guitar Center wanted $43.00!!!!!! for the EL84 Groove Tubes. What a rip off. I found the JJ's for $19.00 and a little shipping. Even the manager couldn't believe the price and checked it again. He said he wouldn't buy them there even with his discount. Check out Tube Depot if your in the market.
Everyone's opinion is a little different about tubes and possible affect of tone. I 'm sure that somebody will correct my opinion and they ought to.

When I changed my factory tubes for JJ Tesla, I felt that I got an overall warmer, more pleasing tone. I don't know if I can describe this with justice but the gain range from clean to a little driven seemed more lineral and defined. I know this has everything to do with the preamp tube but this is my opinion of what changed when I went with the JJ power tubes (this was with the factory 12ax7 preamp tube). I am now running with a 12ay7 preamp tube for the much softer but much more lush tone use for harmonicas. If I were to to play guitar only with my amp, I would go with the Jan Philips 5751 preamp tube. It simply made my Blues Junior sound it's best with a guitar.

Dirtfloorcracker said:
BTW....Guitar Center wanted $43.00!!!!!! for the EL84 Groove Tubes. What a rip off. I found the JJ's for $19.00 and a little shipping. Even the manager couldn't believe the price and checked it again. He said he wouldn't buy them there even with his discount. Check out Tube Depot if your in the market.

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