Old tube testers - worth getting?

[AmpFix]

The best tube tester there is, is an amplifier. I ran a commercial pro audio shop for 30 years. I have a tube tester, I am using it as a footrest as I write. It works. I never use it. In my view, tube testers can verify a tube is BAD, but cannot tell you a tube is GOOD. The conditions a tester puts on the tube are not real world conditions. It will give a good/bad meter reading, but that is almost worthless. The tester can find shorts and gross issues, but won;t tell you the tube is noisy or microphonic or just lost its tone.

Power tubes wear out, it is normal. The small tubes rally don't. They can last decades. They fail, meaning the get noisy or microphonic or just stop working, and then we replace them. But power tubes are like strings, they keep working long after they lost their tone. So keep a set of power tubes you know work. You can plug them into an amp to see if the original tubes are a problem.

AMp working is one thing, amp sounding fresh and alive is another thing, and that is why we replace power tubes. On the other hand, if those 25 year old 6L6s in some amp sound good to the guy, hell, keep using them.

I agree with most of this but I do think that a good, well maintained and calibrated tube tester can tell you whether a preamp tube is getting weak and whether you should change it or not. A tube tester won't weed out noisy or microphonic tubes but it will weed out the really bad ones, before you even install them in an amp.

When someone buys a used amp, who knows what state the thing is in? The 1st thing you need to do, for a tube amp, is check the tubes.

I had a guy come in with a DSL 50, limited edition Orange Crunch. Beautiful amp. He wanted to make sure it was biased right but the amp sounded thinner than my DSL (I a/b's the amps and he could not believe the difference) and had low volume. He bought it that way and didn't know any better. Sure enough, V1 was weak as shown on the tester. I gave him a used tube I had lying around and he left with a huge grin on his face.

The old Eico 667/666 are decent but you need to know how to interpret the charts. They're pretty robust and can be calibrated easily. A favorite of mine is the B&K 707. The switch bank can be iffy so a good and thorough cleaning is a must. They're also pretty easy to clean out.

If the panel meters are not working right, you can replace them with a digital readout (like I did on the Eico). On the B&K, I added a voltmeter out so I can get a good reading.

I regularly test preamp and power tubes on it. Weed out the bad ones and gives you and customers a vote of confidence in the tubes that are installed in the amp. Of course, there are visual clues when examining a tube and the ultimate test is in the amp in terms of noise, bias stability, microphonics, etc.

[gui_tarzan]

I've got a couple of old testers, a Hickok and I think the other one is an Eico. As was previously said, they're good for go/no-go testing and that's what I use them for. Lately I've been using a very small one I got last fall from Enzo for that purpose. Last night it verified a dead heater in a pre-amp tube so it is worth every penny I gave him for it to me, for just that reason. At my age (53) I won't be doing this (repairing amps) for 30 more years and certainly not at a shop level, so it's not worth it to me to spend a bunch of money on a high quality tester.

[Enzo]

Isn't that little tester cool?

I verify open heaters with my ohm meter generally. One major factor in my not using tube testers is the time. By the time I get out the tester, set it up for the tube in question, then test the two halves, I could have simply stuck a couple different 12AX7s in the socket and let my ears tell me if it made the difference.

[Drewline]

Out of curiosity what is this tester?

[Enzo]

Lafayette TE-50. What, maybe 10x12"?

Lafayette TE-50 Tube Tester : NoobowSystems Lab.

[stokes]

Over the years I've used a Hickock 539,a Triplett 3444 and a Weston 918,all good gm testers,but all they tell you is the gm and if a tube is shorted.Knowing the gm alone is useless.I currently use a "utracer" which is a much more comprehensive tester that gives plate resistance,gm,mu etc.,but it still wont tell you if a tube sounds good or is noisy.If all the numbers match the tube manual you can be fairly ..sure you've got a "NOS" tube.I've seen a lot of tubes that have a fairly high gm,but fail in one or all the other parameters,some still sound good some not so much.While it is an interesting tester,it still comes down to listening.

[Drewline]

Lafayette Radio. What an amazing place as a kid. Same with Sears. All those tools. I owned quite a few things from Lafayette. My first electric guitar, fuzz box & a stand alone reverb unit that I remember. By then we discovered Manny's which was only a subway ride away. It all went downhill after that.