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
blindjim OP
3,092 posts
 

Jaybo
OK... i GIVE UP. Wadaya mean? they could wink, blink, and nod for all I'd know. I can't look them in the eye either. So we are eeven.

I did learn one good thing just a few moments ago... the upcoming preamp uses "two" types of tubes... not three. Whew! two 12AT & two 12AX. From the maker all four are but $125. having heard it with stock tubes, it suited me as was.

Newbee

"My biggest fear about owning a tester is just imagine how anal you could get about tube condition and how much time you could spend monitoring their condition."

you're supposed to monitor them too?

Sweet god. and I thought I had this near licked. I'll do my best to restrain myself. Once the lid is on, as you said, there's enough left to futz with without doing that too.

Larry
it matters not how I go about it... I always get a wee bit of a pop. bigger if I shut down the pre first though. I don't do that anymore. but there still is a little pip.. nothing like a serious P-O-P! though.
entrope
482 posts
 
More than you ever wanted to know about tube testers:

http://tone-lizard.com/Tube_Testers.html

As far as acquiring one you will have to search online for a price in your range that meets your needs. Read up first so you are knowledgable about what you need/want. It is easy to overpay but bargains can be had.

As far as the gauge size issue I would recommend a magnifier
of some sort since I know of no tester designed to accomodate the visually impaired. Most testers available were made in a time less sensitive to disabilities.
blindjim OP
3,092 posts
 
Entrope

thanks. Called Sencore up in Sioux Falls today. that was fun... all the way up till we got around to finding out they no longer supported nor made vacum tube testers. I did manage to find one resource. One I'll likely get. tests for gases, shorts, strength, and some other junk... comes with books and a 30 day warranty. Big meter. Also found an online resource for cross referencing tube types - Duncan tube data base. TDB.

Found out about it... haven't found IT yet. I will though.
entrope
482 posts
 
Try this for tube cross reference online:

http://www.nostalgiaair.org/Tubes/
blindjim OP
3,092 posts
 

Entrope
thanks, I will.
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