Testing tubes

[FrankD77]

I have a bias adjust tool on its way.
4 sensors you place under the tubes.
I have a few amps i have my doubt about the tubes.

Is the bias adjust tool also able to test the tubes via the read out? Or is that a wrong conclusion.

A separate tester is very expensive.

 

[Chocol8]

No, a tube tester is needed and they are not all made equal. Unless you are a collector or vendor, a good tube tester is not going to be worth it.

 

[FrankD77]

No, a tube tester is needed and they are not all made equal. Unless you are a collector or vendor, a good tube tester is not going to be worth it.

Seeing the prices i agree. Can buy loads of tubes for that

The bias i want to be able to do myself so the bias tool was worth it

 

[Chocol8]

Yes, it is definitely a big plus to be able to set the bias yourself. As far as testing tubes, having good ones to swap in is usually the quickest and cheapest for most of us, plus it's good to have spares anyway.

 

[BFRaid]

I go to the old school TV/Stereo repair shop the next town over. The guy showed me how to use his tester, then said you are on your own. Now I just walking, grab the tester and go about my business. I always bring him coffee and something from the bakery because he never charges me to use the tube tester.

 

[MadAsAHatter]

The bias tool you have can help you match tubes, but it won't be able to tell you how much life is left or if there's a short.

To match tubes, use your amp with the bias tool. Leave the bias adjust alone and swap tubes in and out. Make note of the bias reading for each tube and pair the ones closest together. Of course you can only do this with the type of tubes your amp is intended for; i.e. don't stick 6L6's in an EL34 amp. Also you don't want to swap tubes while your amp is running. Make sure to tun things off and let tubes cool before swapping.

To test life and shorts you'll need a tube tester. There are different types of testers in just about every price range. You don's actually need one of those $1000+ testers. For Instance I bought an EMC 211 (a tester from the '60's) for about $50 and it suits my needs just fine. It lets me know if there are any shorts and roughly how good/bad a tube is. When you're shopping for these just make sure it's listed as tested and working.

This video should help you understand the different types of testers and which one would be best for you.

 

[FrankD77]

Great. Thanks.

 

[Riffraff]

My vintage tube pulls collection grew quite large a decade ago. I was lucky enough to find a usable tube tester for $75 around the same time. It needed to be calibrated but that ended up being a fairly easy process. It's not a high-end Jackson but it gets the job done.

 

[PatF]

On the amp building forums, the most expert guys there say a Tweed Champ style single ended 5 watter that can take the larger tubes is the best budget tube tester.

 

[Solarflares]

On the amp building forums, the most expert guys there say a Tweed Champ style single ended 5 watter that can take the larger tubes is the best budget tube tester.

They are generally full of shit. No exception in this case. As an audio test maybe, but not an operational one.
It’s no bother at all to send all your unknown-quantity valves to an established tech, and have him test them all for a moderate fee.

 

[PatF]

A single ended cathode biased amp that can take the tubes in the 50 and 100 watters is an operational test. Literally.

 

[Solarflares]

A single ended cathode biased amp that can take the tubes in the 50 and 100 watters is an operational test. Literally.

My first operational test of my untested Budda’s KT66 and GZ34 valves, when it arrived - involved watching smoke and flames coming from the rear, and the explosion took out a channel of my power amp as well.
A simple valve tester, designed to test for shorts - would have saved me a lot of trouble.
But hey, perhaps blowing up a 5E3 amp is low priority in the world of amp builders, and they just toss it and plug in another from their long list of garden-shed amps that didn’t quite cut it.
Here in the real/my world there are protocols for dealing in a professional manner.
An industrial quality valve-tester is the bare minimum kit for ascertaining what you have in your hand - not plugging it into sacrificial gear on the off chance it might work.

A 5E3 is simply a convenient, accessible way of testing known working valves for noise and microphony - never more than that.