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Old 08-13-2007, 12:23 AM   #1
thedeepestgray
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When to replace tubes?


hey guys. i have been wondering lately, since i've had my Peavey XXX head for almost 3 years now when i should replace the tubes, and how i can tell if they need changed. lately i've been getting a lot of feedback and today when i cranked it at band practice, my tone seemed slightly diminished. the feedback isn't really a new thing, so i think the problem might lie elsewhere, but when my tone started to fade, i began to worry. also my sustain has completely gone downhill. whenever i try to hold out notes, it makes a terrible wah-like sound. that problem just began recently, so thats why i was thinking it might be the tubes. I've never replaced them in the 3 years i've had it.

also i was wondering if these problems can be attributed to the preamp tubes or the power tubes. i got some new pickups and some copper shielding tape, so i'm hoping that will kill a lot of the extra noise from my guitar.

so yeah, that's my dilemma. I'd greatly appreciate any help. thanks.
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Old 08-13-2007, 01:59 PM   #2
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yeah i wonder the same question about when to change tubes and what signs to look for..thanks
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Old 08-13-2007, 06:28 PM   #3
Joe King
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You know a tube had gone bad when:

1) Your amp developes and uncontrollable high pitch squealing feedback. (a tube has gone microphonic. a microphonic tube can happen any time, but old age, or a sudden jar while still warm will be the most common causes)

2) Output power loss.

3) Loss of gain in a high gain amp. (can also be caused by a bad cable occasionally. check that first)

4) Tube color changes from warm orange to a blue, pr purple cast. Even if it still works fine, it's on it's last legs. Change it.

5) Amp used at the same settings is suddenly noisy with hiss, or hum.

6) Oscillating tonal changes.

7) Amp suddenly won't stay powered up, and you keep blowing the fuse.

8) When turned off, the tube is not clear but has a slight whitish cast.

These are the most common things I've experienced over the years using a tube amp.





Things to do when re-tubing:

1) If possible buy matched sets. Tubedepot.com offers to test the tubes for compatibility when you buy new ones.

2) When changing the power tubes also get the amp re-biased

3) If you have a Mesa, use Mesa tubes, and you don't need a re-bias.

4) Never touch the tube you are replacing bare handed. If you do, clean it with alcohol, let dry, and re-install it.

5) Never use anything metal around tube sockets to help pry it out. Not only can you shock the hell outta yourself even if it's not plugged in, you can damage the tube socket. The reason you can still get shocked with the amp unplugged is based on the use of a capacitor in most tube amps. It's basically a high voltage battery, and accidently arcing across the right set of pins will result in a good jolt.

6) Check tube compatibility. There are lots of replacement tubes that can be used like a Marshall uses an ECC83 preamp tube, but you can use a 12AX7 in place.


Tube life depends largely on use. I've seen pre-amp tubes last years, and seen them go in 8 months. High volumes, frequently moving gear, and overly high voltage at the wall are all factors in how long a tube set lasts.

It's never the whole set that goes, usually just one, but that's the indication it's time. With the exception of accidently breaking a tube while moving the amp.



Tube amp tones are heavily colored by the type of tubes in them. You can find tubes that brighten a dark amp, darken a bright amp, lower or raise gain, change power output, so on and on.

Here's a couple of links that are helpful.


http://store.tubedepot.com/

http://www.rocknrollvintage.com/amp-tube-charts.htm


At tube depot, if you click on the tube brand, and type, it gives you a brief overview of the tonal characteristics.

Hope any of this helps


Jay
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Last edited by Joe King; 08-13-2007 at 06:40 PM.
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Old 08-14-2007, 12:35 AM   #4
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Joe King's post should be a sticky!!!!
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Old 08-14-2007, 04:44 AM   #5
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Done...Thanks alot Joe King
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Old 08-15-2007, 10:13 AM   #6
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Ya'll are more than welcome.

Just wanted to add that if the preamp tubes are still good, you CAN replace just the power tubes instead of a whole set, or leave the power tubes and replace the preamp tubes. You don't need to shell out for a huge set of tubes all at once every time they go. Tube life for preamp tubes is generally much longer than the power amp tubes, so a two to one, or three to one ratio of changing the preamp compared to power tubes would be a good way to think of it.

I usually keep a spare couple of both the preamp and power tubes, and keep them on hand in case one goes bad, kinda like having a spare tire.

Then when I replace the set, I keep that one or two out again to have on call for gigs or whatnot.

Cheers!


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Old 08-16-2007, 11:45 AM   #7
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wow. thanks man. you've been exceptionally helpful, even though you are the bearer of bad news for me lol. Signs 1,3,5,and 6 all apply to my amp, so i think i am going to invest in some new power tubes. I'm hoping those will fix the problem. I'm pretty sure my preamp tubes are still good, because my tone is still solid, and the gain in my amp is still where it has been since i've had it.

Thanks a bunch for all your help.

p.s. i agree...joe's post should be stickied.
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Old 10-15-2007, 10:05 PM   #8
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Quote:
Originally Posted by Joe King View Post
You know a tube had gone bad when:

1) Your amp developes and uncontrollable high pitch squealing feedback. (a tube has gone microphonic. a microphonic tube can happen any time, but old age, or a sudden jar while still warm will be the most common causes)

2) Output power loss.

3) Loss of gain in a high gain amp. (can also be caused by a bad cable occasionally. check that first)

4) Tube color changes from warm orange to a blue, pr purple cast. Even if it still works fine, it's on it's last legs. Change it.

5) Amp used at the same settings is suddenly noisy with hiss, or hum.

6) Oscillating tonal changes.

7) Amp suddenly won't stay powered up, and you keep blowing the fuse.

8) When turned off, the tube is not clear but has a slight whitish cast.

These are the most common things I've experienced over the years using a tube amp.





Things to do when re-tubing:

1) If possible buy matched sets. Tubedepot.com offers to test the tubes for compatibility when you buy new ones.

2) When changing the power tubes also get the amp re-biased

3) If you have a Mesa, use Mesa tubes, and you don't need a re-bias.

4) Never touch the tube you are replacing bare handed. If you do, clean it with alcohol, let dry, and re-install it.

5) Never use anything metal around tube sockets to help pry it out. Not only can you shock the hell outta yourself even if it's not plugged in, you can damage the tube socket. The reason you can still get shocked with the amp unplugged is based on the use of a capacitor in most tube amps. It's basically a high voltage battery, and accidently arcing across the right set of pins will result in a good jolt.

6) Check tube compatibility. There are lots of replacement tubes that can be used like a Marshall uses an ECC83 preamp tube, but you can use a 12AX7 in place.


Tube life depends largely on use. I've seen pre-amp tubes last years, and seen them go in 8 months. High volumes, frequently moving gear, and overly high voltage at the wall are all factors in how long a tube set lasts.

It's never the whole set that goes, usually just one, but that's the indication it's time. With the exception of accidently breaking a tube while moving the amp.



Tube amp tones are heavily colored by the type of tubes in them. You can find tubes that brighten a dark amp, darken a bright amp, lower or raise gain, change power output, so on and on.

Here's a couple of links that are helpful.


http://store.tubedepot.com/

http://www.rocknrollvintage.com/amp-tube-charts.htm


At tube depot, if you click on the tube brand, and type, it gives you a brief overview of the tonal characteristics.

Hope any of this helps


Jay
Thanks alot Jay! But I do have a question, where would the tube change colors? Where it burns? Around the caseing? Could you please explain! no use for that smilie but I like it.
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Old 10-29-2007, 09:19 PM   #9
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Yep, where the tubes glow. The little filament will change color giving of a purplish/blueish hue.

That's a tube's sign of the "blue screen of death".
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Old 11-15-2007, 03:50 PM   #10
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Old 03-17-2008, 03:36 PM   #11
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This is for The Deepest Gray..Yeah dude, sounds like the wah sound is probably coming from your pre-amp tube with a metal cover on it ie your tube that can go microphonic on you, picks up radio station and can just creat a lot of wah and sucking sounds. It could be a bad power tube as well. This is what I do. Take all of your tubes out after you unplug everything from power! Make sure your fuses are good and slow-blo's. The turn amp on for just a second then turn off immed! It shouldn't hurt anything. If you don't blow a fuse then replace all of your tubes, especially after 3 years! You have 1 or more bad tubes. And actually in your situation it's what you want believe me! No blown fuse! This means that everything besides your tubes are ok. Check it out and let me know if ya get a sec! Good luck I just retubed my Marshall tsl-100 head w some JJ-Teslas! Screamin! my screen name is marshalltsl100 SeeYa!

Last edited by marshalltsl100; 03-17-2008 at 03:37 PM. Reason: wanted to make sure the right user read it.
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Old 04-11-2008, 08:17 AM   #12
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thanks for making this thread. i've wondered the same thing
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Old 07-02-2008, 12:28 PM   #13
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please watch many advices about tube replacementhttp://www.kldguitar.com/support.htm
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Old 08-24-2008, 12:26 AM   #14
Buck Naked
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I replace every ^ months its expensive but worth it!!The sound is much moore bright and focused
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Old 08-26-2008, 05:05 AM   #15
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use your ears when deciding to replace a tube. be warned that cheap tube amps will have the same sound quality issues regardless of what tubes you put in them. usually its the cheap caps and wimpy transformers. I have a solid state amp that has a tube pre and when it went bad, the thing was absolute garbage. just sounds muddy, muffled. actually it reacts to this pitch between the 12th and 13th on the low E. if I bend 12th fret it hits it dead on and sounds like a blown speaker.
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