simple way to test tubes?

[blakejcan]

I have probably about 14 tubes that are all mixed up in my parts drawer. Some I know are brand new and never used. Some came out of an amp where I blew a fuse. I haven't touched them in years and whatever system I had in place at the time to keep them organized has been destroyed and now I am not sure what is what.

Is there a relatively simple way that I can test to see which ones are good without risking blowing up myself or my amps?

 

[NegativeEase]

Re: simple way to test tubes?

I have probably about 14 tubes that are all mixed up in my parts drawer. Some I know are brand new and never used. Some came out of an amp where I blew a fuse. I haven't touched them in years and whatever system I had in place at the time to keep them organized has been destroyed and now I am not sure what is what.

Is there a relatively simple way that I can test to see which ones are good without risking blowing up myself or my amps?

they do make tube testers.

I usually use an inline bias probe and see if the current is stable and if it has drifted far of the set point -that's usually the sign of one that's getting old -as everytime you warm them up and play, the grid, plate, filament etc are being re-anealed -and that over time affects efficiency and conductivity as the metal loses it's composure.

 

[hamerfan]

Re: simple way to test tubes?

You can measure the heaters with a multimeter, but thats it.
First i do a optical inspection: any burned wires or black spots on the surfaces or white getter? If not, you can test preamp tubes by putting them into an amp. There is no danger. Same with rectifiers.
Power tubes: I take them to a amp tech and he checks them with a tube tester. Little hint: he can do a kind of rough grading while testing to get matching pairs or quads out of a bunch of singles.

 

[JamesPaul]

Re: simple way to test tubes?

I have not had access to a tube tester for a while. When I did, a tube tester was great at identifying bad tubes. It typically takes more specialized testing equipment to determine if tubes are ultimately "good" for use in an amplifier.

Without a tube tester you can look for the "Visible Signs" listed here - https://blog.thetubestore.com/how-to-tell-if-your-tube-is-bad/
Exclude the purple glow and red-plating as your tubes are not in an amplifier.

Then you can use your multimeter/ohm meter to ensure there is continuity between the heater filament pins and the other element pins are not unexpectedly connected/shorted as described here - https://www.youtube.com/watch?v=_M_lCwQgCMA

After that you usually have to plug the tubes in to test for microphonics and other issues. This is where you would consider the savings using an unknown condition tube vs. the cost of potentially repairing the amplifier. The rest of the Tubestore link describes how to determine if the tube is bad for use in an amp.

 

[DonP]

Re: simple way to test tubes?

Find someone helpful in your area that can test tubes. I've seen listings on the Audio Karma forums by area. Craigslist?

 

[Phantasmagoria]

Re: simple way to test tubes?

For a fraction of the price of a decent tube tester, you could buy a Bugera G5 infinium.

The Infinium tech tells you if your power tubes are working or not ..the amp's a bonus

 

[ehdwuld]

Re: simple way to test tubes?

I think all the Infinium series come with the tube monitor

some Peavey amps as well

 

[JamesPaul]

Re: simple way to test tubes?

Aye the TSI (Tube Status Indicator) on the Peavey MH's monitored the power tubes. Still that is a far cry from a drawer full of unknown condition tubes.

 

[Phantasmagoria]

Re: simple way to test tubes?

I think all the Infinium series come with the tube monitor

some Peavey amps as well

Orange had them too....they're all the same thing. There was an OEM manufacturer with a patent for these things supplying them to all the amp makers. I remember visiting their site 5-6 (7-8?) years ago. You coud buy the unit online and install it in your own amp build if you wanted to..it did'nt even cost that much.

Not sure if they're still around. I think after the contracts came in from the big amp manufacturers they stopped selling them retail..