Tubes going bad?

?ing my education

What are some signs that tubes might need to be replaced?

Pacomc79

wierd power issues, farting out, sound quality in the toilet, ringing sputtering etc.

?ing my education

ah, bingo. Must be time for some new tubes.

paco, can you tell me how to replace them. I have never done it before. I have a Fender Blues Jr., which I bought used. I am going to get 2 JJ EL84's and 3 Tung-Sol 12AX7's (I researched that part of it). I looked at it last night and I think I might have it figured out but before I screw something up, I would like to hear from some one who knows.

Thanks.

moster78

?ing my education wrote:

ah, bingo. Must be time for some new tubes.

paco, can you tell me how to replace them. I have never done it before. I have a Fender Blues Jr., which I bought used. I am going to get 2 JJ EL84's and 3 Tung-Sol 12AX7's (I researched that part of it). I looked at it last night and I think I might have it figured out but before I screw something up, I would like to hear from some one who knows.

Thanks.

How long they last for you? I have the exact same amp. Also, let us know how those tubes work out for you for when I need to replace mine! Thanks man.

sennin

Mine started buzzing/ringing.

ianvomsaal

It all depends on how hard you've driven them, and how long they've been used. You might need a whole new set of tubes. Generally crackling, popping, squealing, hissing, loss of overall power, and loss of tone can all be signs of tubes on the end of their useful life (thus you might want to think about changing them). Or maybe there's a simpler solution . . .

The majority of tube problems come from one culprit, the V1 preamp tube (this is the 1st tube to check) - you might have a bad V1 preamp tube. Try to remember this, the V1 tube gets the brunt of the abuse since it's the 1st tube in the chain - everything hits this tube 1st - and anything wrong with this tube just gets amplified down the line (squealing, fuzz, crackling, popping, hissing, tone loss, ect).

One thing you can try is just replacing the V1 preamp tube with a new one (the 12AX7 in the V1 spot). If nothing changes for the better, remove that new tube, put the tube that you took out back into it's original place, and move to the next space with the new tube. Just move on down the line until you find the bad one. Sometimes all the tubes are kind of shot, thus you just need all new preamp tubes (BUT THIS IS NOT AS COMMON).

As far as power tubes go - it's best to replace them all at the same time.

This is just my experience since Amp techs get a bit of $$$ for their services - and if all they had to do was go on down the line, and replace one bad preamp tube, that would suck. They'll charge you $8-$15 for that single tube, plus a flat rate (usually an hour) for their bench time - took them like 5-10minutes. Think about the money you just saved by doing it yourself.

Changing tubes are easy - just make sure the amps off and unplugged (the amp has enough stored power to literally kill you, so just turn it off, unplug it, and flip the power switch on and off a few times to release the charge - do the same with the standby) - grasp the tube with your fingers and gently but firmly pull and slightly wiggle it until it releases - you'll notice that there are many small pins on the bottom of the tube, and one space without a pin - when you replace the tube you just line up all the pins and holes - it's easy, just push and wiggle slightly until it seats well - don't worry if you slightly bend a pin, just bend it back and continue.
Cheers . . .

- Ian C.T. vom Saal

Pacomc79

Ian as usual said it all perfectly.

My #1 issue has been V1, the EH tube I used didn't seat well. I swapped it back out and it's been fine since.

If you've had it a while and don't mind spending the 60 bucks or so it's going to take to retube it all the way go for it.

The Tung Sol's I've come across have been great. You could try ordering one for V1 first, and check that and then change the rest.

The Blues Jr is cathode biased so you won't need to hire an amp tech to change the EL84's because it's built to operate within a certain tolerance, but it never hurts to check the idle bias. JJ's should be fine. matched pairs only.


Important technical note on EL84/6BQ5s.


From Mike, KCANOStubes.

{Most guitar amps that use these tubes are cathode biased (aka "self biasing") and generally don't require rebiasing when installing new EL84s. However, it is always best to check that the idle power of these tubes does not exceed the maximum rating (12watts) in your amp. Be sure to check or have your amp tech check the idle current/power when installing new EL84s. With some pairs/quartets (and brand, NOS or new production) the tubes will run too hot and have a very short life. If the tubes run too hot, a larger value cathode resistor must be installed. Please heed this warning as we will not be responsible for tubes that expire quickly. Your equipment is your responsibility.}


Oh and if you want to save a little money on the preamp tubes, the Sovtek 12AX7LPS's are pretty nice.

?ing my education

moster78 wrote:

How long they last for you? I have the exact same amp. Also, let us know how those tubes work out for you for when I need to replace mine! Thanks man.

Not sure how old the amp actually is. I am sure it is 3-4 years old plus I have had it for over a year. So I am not sure how hard the amp was played before me but I play it probably 4-5 times a week.

I have been getting all the problems described. The tubes were recommended by Lord Valve over on the Guitar Hub site. I think i am going to order replacements for all.

Thanks for the technical note pac, I will check all that out. Thanks to you Ian for describing how to swap them out.

All info is greatly appreciated.

Pacomc79

?ing my education wrote:

Not sure how old the amp actually is. I am sure it is 3-4 years old plus I have had it for over a year. So I am not sure how hard the amp was played before me but I play it probably 4-5 times a week.

I have been getting all the problems described. The tubes were recommended by Lord Valve over on the Guitar Hub site. I think i am going to order replacements for all.

Thanks for the technical note pac, I will check all that out. Thanks to you Ian for describing how to swap them out.

All info is greatly appreciated.

Lord Valve is the man.

ledhed43

ha, i just changed the 12ax7's in my blues junior last night. the amp was "growling, hissing, and popping" in my cousin's terms. he brought over some matched chinese 12ax7's and you just pop out the old ones and pop in the new ones. amp turned off and unplugged of course. purest use gloves, but i am no purest so i just used my hands. the hardest part is lining up the pins. i have no idea about the el84's, i didnt change them cause my cousin didnt have any of those laying around and the amp works without changing them.

can anybody tell me why there is the spring bracket over the el84's in the blues junior?

Pacomc79

ledhed43 wrote:

ha, i just changed the 12ax7's in my blues junior last night. the amp was "growling, hissing, and popping" in my cousin's terms. he brought over some matched chinese 12ax7's and you just pop out the old ones and pop in the new ones. amp turned off and unplugged of course. purest use gloves, but i am no purest so i just used my hands. the hardest part is lining up the pins. i have no idea about the el84's, i didnt change them cause my cousin didnt have any of those laying around and the amp works without changing them.

can anybody tell me why there is the spring bracket over the el84's in the blues junior?

To cut down on thier movement and keep them properly seated in the socket.

because it's a combo amp the speaker causes vibrations. The retainer simply helps keep them from vibrating so much and it helps keep them seated.

HailHailVitalogy

After putting Winged C's into mine...my amp sounds as good as it did the first day I opened it up

ledhed43

Pacomc79 wrote:

To cut down on thier movement and keep them properly seated in the socket.

because it's a combo amp the speaker causes vibrations. The retainer simply helps keep them from vibrating so much and it helps keep them seated.

makes perfect sense. im not looking at the amp right now, but i think the 2 el84's sit right behind the center of the speaker. i knew there had to be a good reason, just couldnt figure it out myself.

harrisonmerwin

my brand new, out of box Fender Blues Deville 410 reissue didn't come with any tube protection...i was a little shocked, dont they come shipped with a foam thing?

ledhed43

not sure about the foam protector, but what kind of tubes came in that amp, sovtek? i am just wondering if fender puts sovtek in all their amps or just the low end ones like my blues jr.

ledhed43

ok more tube questions. like i said i changed the 12ax7's and everything was fine. well after i played a little while today, my amp started making another bad noise, different than before i changed the other tubes. so i checked the back to make sure they were all set nice and the el84's were not sitting right. this just after i found out what that retainer was for. well obviously mine isnt doing a great job, i adjusted the el84's and the retainer, and all seems well, but is there anything i can do to keep them sitting nice or is it something i will need to check from time to time? btw i havent had any problem with this until the past week.

ianvomsaal

Yes that can happen - if you move your amp around (picking it up and setting it down) the tubes can get a little jarred (yes that's what the retainer is for, but many aren't the end-all). Just make sure you check them every once in a while and you'll be fine. Also, some V1 slot Preamp tubes have a little metal shield/cover on them (this is not to hold it in, but more-so to help filter out any noise/microphonics/interference - as I said before, this in an important tube in the chain).
Cheers . . .

- Ian C.T. vom Saal