2. misc-audio
  3. 1170020061

how do you know a bad tube?

I'm thinking of winding up all or at least mostly with tube gear. that said, how does a person know for sure which tube device needs a tube?

By that i mean, if you have multiple preamps, and amps, then I'd see it as not a lot of trouble determineing which one has perhaps an issue. but if you only have one pre and one amp both with tubes and things begin to sound funky, how then do you tell which unit is the culprit?

Past that then, how do you know which tube? (given there aren't any indicators on the chasis, and the tube itself isn't dead blown). ?? ...and apart from having on hand dupes of all the tubes in the system.

I am overlooking the obvious here for a reason. I'd as soon not have to get a tube tester. Unless there is a mighty simple one to use which has an oscillator in it as well as meters.

Sorry if it is a dumb question, but sure seems like a simple answer here will come in handy later on... as I'm looking for an "in house" solution that ain't way expensive and is simple enough tactilly for me to use.

thanks much
blindjim
larryi
3,979 posts
 
You should have at least one extra set of tubes. That extra set will provide the tubes to swap and test for the bad unit. It also means your equipment is never out of commission just because a tube is going bad.
larryken
537 posts
 
Jim,
when I owned the VK5i I found switching tubes side to side could usually isolate or even make go away the problems I was having with noise....like other posters said, if the problem switches to the other channel then you have identified the culprit.
regards,
LarryK
blindjim OP
3,092 posts
 
Larryken
Got it. Thanks. i never did notice much of a diff in the VK5i, from swapping from side to side... as the thing biases itself each time... but then I must never have had a severely poor tube. the biggest/best thing in that unit I found was having all the same tubes in the signal path, and play with something in the shunts. ultimately, i found that the simplest and best way to outfit the unit.

Larryi
it sure does seem the way. Another set entirely. Geezzz Louise.

See I was thinking there is some really neat gizmo out there that one can plug a tube into for just strength or short testing. Like a wiggins voltmeter.... and I'd not have to spend hundreds for a tester i probably cant read well enough anyways... and need to periodically recalibrate.

Oil well. Thanks. Thanks very much... of course if there is someone out there who knows of a simple tester which does a good job is sturdy, with B-I-G meters, and seldom requires calibration...I would like to hear about it, and where it is available.

A couple of the tube amps I am thinking about have quite a number of tubes in them... and some singles in there as well... an affordable tester I could use does seem relevant to have if you're going to pursue an all tube system, doesn't it?.
entrope
482 posts
 
Tube tester.
capt369
152 posts
 
Blindjim. I think others have addressed your tube dilema very well. I`m curious, after reading your "what would your next upgrade be" thread on your system page, what your impression of Herbies tweaks is and how you`re doing with the room tuning.

I`m a big "Herbies" fan and have implemented (one at a time) every dampening tweak that Steve offers. Each implimentation isolated instruments more and more and brought a more realistic soundstage. I`m very happy with the results.

I`m also doing some room tuning and am curious as to how you`re coming along with yours. Maybe you could update your other thread (if you feel like it). It was an interesting read for me, and I assume, others.
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