Metropoulos Forum

What is the best tube tester to get for testing 12AX7's, EL34's, EL84's, 6CA7's, 6L6's, and other types of tubes for guitar amps?

I've seen a lot of people with the Hickok 600 model, but I thought I'd check with you all to see what make and model you would recommend.

Ebay seems to have a lot of them up for sale... What am I looking for here guys?

Any advice would be much appreciated...

The best, IMHO, is any of the TV7/U variants. Military issue. I once had one that I got at a hamfest for $5.00 Lent it out and it dissappeared.

They go for hundreds now.

Hickoks are always good, I've got one of the true pearls, the 539C. Unfortunately, anything you'll buy in working condition will still need to be calibrated ($$$).

That's a good post question. I've been thinking about this myself. I've seen the Hickoks going for big bucks. Is there anything new available at a reasonable price for the hobbyist to do some basic checks on the common tubes (12AX7s, EL-34s, 6L6s, etc)?

From what I've read, the Hickoks are the most flexible. They sure are pricey, though. I use a B&K 707. It's a true mutual conductance tester like the Hickoks but a little cheaper. For what I require, it fits the bill perfectly. It uses lots of sockets so you don't have to change as many settings as the Hickoks. But of course, if I had the choice, I'd go with the Hickok 539.

Remember, most of these testers don't use high voltage on the plates so they're virtually useless for "matching" power tubes. I think there's a Hickok that might use real world voltages on the tubes but I don't remember which model #.

Check out this guy's site. It has a good overview of what to look for:
http://www.tone-lizard.com/

So, I wonder if anyone's designed a DIY tube tester that works for a subset of common tubes, and runs at high plate voltages? Seems like it shouldn't be impossible. In fact, I think it would be pretty easy to beat the accuracy of the old circuits with today's low-tolerance parts. Could even use a digital readout...

BashCoder wrote:So, I wonder if anyone's designed a DIY tube tester that works for a subset of common tubes, and runs at high plate voltages? Seems like it shouldn't be impossible. In fact, I think it would be pretty easy to beat the accuracy of the old circuits with today's low-tolerance parts. Could even use a digital readout...

Here's what people have suggested on a few other boards I posted on, including a power amp tube tester that uses up to 400 volts. Neither are cheap, but neither is a calibrated Hickok, and these look like they would give you better overall information if you got both of them...

Pre amp tube tester ($850)

http://www.vacuumtube.com/toppage31.htm

Power amp tube tester ($545)

http://www.maximatcher.com/index.htm

Unless you're really concerned about a tube's curves, just sticking a tube in an amp and firing it up and measuring the current draw is a cheap simple way of matching tubes.

Coolness -- thanks for posting those. They both look great.

I also wonder if I scour some of my old Ham Radio Handbooks, will there will be an essay or two on how to measure mutual conductance? If someone released something like that as a kit, it would be great.

Back when I had my TV7/U, the irony was not lost on me that I was using an old tube device to test old tubes!

This one is very cool, but is the most expensive of the lot....

http://www.autobias.com/index.html

I think George has the Maxi Matcher?

Allen

dynaman wrote:Unless you're really concerned about a tube's curves, just sticking a tube in an amp and firing it up and measuring the current draw is a cheap simple way of matching tubes.

You bet -- that's why I'm the thinking that all you have to do is build a fairly basic circuit and measure the right things across the right pins. The guts of most of these tube checkers basically consist of a bunch of wire and a handful of parts. The complexity comes from trying to test every possible tube type. It can't be too hard to come up with something like the Vacuum Tube Valley thing, minus a few bells and whistles.

Before you decide to buy a tube tester, better read this:

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

Larry

Good read. I don't ever buy vintage or used tubes, so I think I will just continue to buy new tubes and take my chances. Only thing that matters to me is they work of course and are matched within 5% for bias current draw in the amp.