It is currently Mon Mar 16, 2020 2:54 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 8 posts ] 
Author Message
Post subject: How do you know when tubes are bad?
Posted: Thu Feb 21, 2008 6:18 pm
Offline
Hobbyist
Hobbyist

Joined: Thu Aug 23, 2007 5:49 pm
Posts: 6
How would you know when to replace them??
thanks!!


Top
Profile
Fender Play Winter Sale 2020
Post subject:
Posted: Mon Feb 25, 2008 6:23 am
Offline
Rock Star
Rock Star
User avatar

Joined: Tue Aug 07, 2007 2:19 pm
Posts: 8827
Usually ether when you start blowing fuses (power tubes), or when you get weird distortion, unwanted feedback, etc. It depends on a lot of factors too. I've had some tubes last years and years and some go after a couple of months. You'll know, you'll hear it.


Top
Profile
Post subject:
Posted: Mon Feb 25, 2008 1:25 pm
Offline
Hobbyist
Hobbyist

Joined: Thu Aug 23, 2007 5:49 pm
Posts: 6
thanks!


Top
Profile
Post subject:
Posted: Mon Feb 25, 2008 5:07 pm
Offline
Hobbyist
Hobbyist
User avatar

Joined: Mon Feb 11, 2008 3:37 pm
Posts: 81
Usually tubes wear out a little at a time unless something goes wrong such as a short in the tube and the amp dies. More on this later. As the tubes wear out you will lose some highs and the amp will lose some gain these symptoms are hard to tell until things get real bad or the amp stops working. I recommend testing your tubes about once a year on a good tube tester, that's what I've done for over 40 years. I grew up in a TV repair shop owned by my dad and learned about tube amps as a kid, I do my own repairs and some for friends. I'm not a Amp Tech, I could be if I wanted to be but I'd rather be a musician.

Sometimes you have a major falure of a tube, this is more common with modern cheap power tubes but it happens to good brand tubes as well. When this happens and the amp dies, usually it's something like a grid resistor on the tube socket, most fenders with 6L6 and 6V6 tubes use a 2 watt 470 ohm resistor which blows like a safety fuse and saves the amp from a worse fate. I must have done 50 of these repairs in tha last 10 years most were left over Cold War import tubes. I bet you know where they came from. Things have gotten better but I still keep a stash of NOS RCA's for my Twin Reverb.

One thing about Fender amps, at least the older ones they seem easy on tubes and the tubes last along time. I've had some last 10-15 years in studio amps gigging that may only have lasted half as long. I'm not sure the new amps have the same spec's and the tubes sure don't seem to hold up as long. But the higher the gain and the more you push the amp the shorter the life of the tube and maybe your ears.

My advice is, test your tubes once a year and see how long they last.


Top
Profile
Post subject:
Posted: Wed Feb 27, 2008 2:46 pm
Offline
Hobbyist
Hobbyist

Joined: Sun Jul 15, 2007 12:29 pm
Posts: 5
Hello,

My Fender Twin - 2007 model, less than a year old, started sounding like crap the other day, mainly on the distortion chan. I turned everything off and then fliped the switch to full power, and powered it back on, and it sounded a lot better, still not right, but better. I suspect that it is the tubes.


When I take it to a service center, can I ask them to replace the tubes with better quality tubes, and what should I ask them exactly? I'm a player, not a tech, so any information would be most appreciated.

Appreciate all input, thanks.


Top
Profile
Post subject:
Posted: Wed Feb 27, 2008 8:00 pm
Offline
Professional Musician
Professional Musician
User avatar

Joined: Tue Jul 17, 2007 3:08 pm
Posts: 2889
Hey did ya check the tubes to make shure they were seated properly ?

I cant tell ya how many "blown tube amps" I have "fixed" by checking to see if the tubes were seated properly only to find one loose goose in there.

I had a guy give me a 1970's Vibro Champ, it had a loose tube and worked perfectly and no, he wouldn't take it back when I told him how simple a fix it was.

before you start investing in tubes check the fit.

and hey be carefull !!!!!!


Top
Profile
Post subject:
Posted: Thu Feb 28, 2008 3:47 pm
Offline
Hobbyist
Hobbyist
User avatar

Joined: Mon Feb 11, 2008 3:37 pm
Posts: 81
blues bondsman wrote:
Hey did ya check the tubes to make shure they were seated properly ?

I cant tell ya how many "blown tube amps" I have "fixed" by checking to see if the tubes were seated properly only to find one loose goose in there.

I had a guy give me a 1970's Vibro Champ, it had a loose tube and worked perfectly and no, he wouldn't take it back when I told him how simple a fix it was.

before you start investing in tubes check the fit.

and hey be carefull !!!!!!


Funny you say that you've fixed amps with a loose tube just by installing it properly. I've seen it happen many times myself. I picked up an amp real cheap a few years ago because the guy said it was blown, no volume lots of distortion, he had even bought all new tubes. So I bought it and took it home. Turned out the speaker jack was plugged into the ext. plug not the speaker plug when I switched it, it worked fine. I felt like I cheated him so I offered it back to him for the same price.


Top
Profile
Post subject:
Posted: Fri Feb 29, 2008 3:36 pm
Offline
Hobbyist
Hobbyist

Joined: Sun Dec 09, 2007 3:12 pm
Posts: 3
You guys did the right thing. You're restoring my faith in musicians. Good for you. :D


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: