Rob Tahan
Member
What are some typical specific indicators that the tubes are going bad and need to be changed? I think the time is here and am starting to hear a few differences
hunter
Active member
For me it's usually time when the old tubes have been in more than 2 weeks and then I read on some forum that tube XYZ is the secret sauce combination with my amp and I suddenly think that the current set doesn't cut it anymore 
PaulyPanacea
Active member
If you are starting to hear differences in the tone you are used to...then its time. Your ears are usually one of the best judges. No real "set time" when tubes go bad..could be 10 years, 10 months, 10 days or even 10 minutes!
studiojig
New member
Excessive hum/hiss/noise, feedback or whistling sounds.
nbarts
New member
Rob,
If you feel like the tone ain't there change the V1 first. It could be all you need to do.
If you feel like the tone ain't there change the V1 first. It could be all you need to do.
steve_k
New member
hunter":24buxqry said:For me it's usually time when the old tubes have been in more than 2 weeks and then I read on some forum that tube XYZ is the secret sauce combination with my amp and I suddenly think that the current set doesn't cut it anymore
Now that is damn funny
Steve
steve_k
New member
Rob Tahan":1cehjs8c said:
Usually when I see smoke or hear a kaboom....
Power tubes are like light bulbs - they mostly just go. Depends on a few things though:
How are you tubes biased - hotter or cooler? The higher in range they are biased, the shorter the life.
How much do you play? Everyday, a few days a week, on the weekends.
Do you crank it up, or keep it bedroom level?
Factor in some luck.
Usually, I will try and every few months check the bias of the tubes. Most of the time, you will find them still within 10% of each other. Sometimes not though. If you find one that has really slipped out of range, that may be a sign of failure ahead. With the VH4, if you go to the trouble to pull the chassis to check the bias, you might as well change the damn tubes out. With the Herbert and external probes, you might get by without doing so.
Power tubes not glowing fairly well or one in comparison to another is a fairly good sign, or the telltale red top.
Preamp tubes rarely go bad. But, if I have the chassis out, I will usually change V1, V2 and V3 just for good measure.
I bought a 1978 Marshall Super Bass last year. It still had the original GE 6550's and ARC preamp tubes in it. The bias was all over the map, but every one of the bastards lit up and the amp will blow windows out of the house.
Maybe Peter should put an hour meter on the amp, sort of a tube odometer that you can reset on tubes changes
Lose a power tube though, it won't be the end of things, just a little loss of output.
Steve
Rob Tahan
Member
Yea I definitely feel like I'm getting a lot more feedback especially on channel 3. And the gain is only at 2 o'clock. I can crank the gain on channel 2 to 3 o'clock or more and barely get anything. That may also have something to do with the tone seeming a little less mid heavy..?studiojig":p485ogi8 said:
studiojig
New member
Rob Tahan":19fllpwe said:
Which amp? The herbert or the vh4?
Ailean
New member
It's around the time I start thinking 'I wonder if I should change my power tubes', becuase from that point on I keep thinking it, until I change them and find out I didn't need to. 
realityescapes
New member
Rob Tahan":18m37acf said:
I have a herbert and on channel 3 and it is also pretty noisy with almost the exact feedback/ whistling sounds you described. I almost cant stop playing on channel 3 when its on, just too much feedback. Im assuming this is not normal. Channel 2 with any amount of gain though is whisper quiet so i would assume its a preamp tube somewhere........
Ventura
Well-known member
I found that tubes are usually best visually inspected to know if they're goners... I mean, ya, if ya hear one fizzle and snap - that's obvious, but for the most part, the plates wear down on tubes very gradually...and the change in tone, is very gradual, and in my case anyway - it was so gradual that I became accustomed to the crapped out tubes over time. Didn't realize I needed new tubes until they went in - then it was like - WHOA!!!!!!!!
Visually, lots of grey/sooty coating on the inside, also, when they're powered up with a load, check for inconsistencies in the glow/arc in a dark room on the top of the tube and through the sides. Secondly, just kinda figure out how many hours they've been in there, and at what volume levels you're playing. All things being equal - an amp that's being gigged at 12:00 levels and beyond is going to wear a helluva lot quicker than a 7 or 8 o'clock level user. I've had tubes last months, and I've also had tubes - get this - last 15 years in one amp!!!! It was a studio miked, 1x12 combo that rarely got cranked. It was our jazz/clean amp in the studio. Go figure... I've had a Mesa that ate through tubes like cereal in the morning - but that was a stage amp that always got pushed to deafening levels... We started realizing it wasn't "deafening" after a couple months. Replaced the tubes - taaaaadaaaa - deafening again.
Hope this helps.
V.
Visually, lots of grey/sooty coating on the inside, also, when they're powered up with a load, check for inconsistencies in the glow/arc in a dark room on the top of the tube and through the sides. Secondly, just kinda figure out how many hours they've been in there, and at what volume levels you're playing. All things being equal - an amp that's being gigged at 12:00 levels and beyond is going to wear a helluva lot quicker than a 7 or 8 o'clock level user. I've had tubes last months, and I've also had tubes - get this - last 15 years in one amp!!!! It was a studio miked, 1x12 combo that rarely got cranked. It was our jazz/clean amp in the studio. Go figure... I've had a Mesa that ate through tubes like cereal in the morning - but that was a stage amp that always got pushed to deafening levels... We started realizing it wasn't "deafening" after a couple months. Replaced the tubes - taaaaadaaaa - deafening again.
Hope this helps.
V.
studiojig
New member
realityescapes":1xf4xvoo said:Rob Tahan":1xf4xvoo said:
I have a herbert and on channel 3 and it is also pretty noisy with almost the exact feedback/ whistling sounds you described. I almost cant stop playing on channel 3 when its on, just too much feedback. Im assuming this is not normal. Channel 2 with any amount of gain though is whisper quiet so i would assume its a preamp tube somewhere........
I would concur with your assessment - that most definitely sounds like a preamp tube that's gone/going south on you. There's another post around the forum that maps our each pre-tube slot to the channel (or channels) they affect. I'd search for that and try swapping out the appropriate tube before just scrapping 'em all. That way you could isolate the problem and save some $$