preamp tube testing chassis

[Quatro]

At some point, ( i can't even remember if it was on this forum) I saw a schematic for a test chassis ( champ type maybe?) that had six or so preamp tube sockets and a switching system. The idea was you could plug in a bunch of preamp tubes and switch between them to a/b a whole pile at a time. I searched here and on the web and can't seem to find it. Is anyone familiar with this schematic or where to find it?

Thanks

[HotBluePlates]

What are you trying to test?

In many cases, testing in an actual circuit is the gold standard. Everything else has problems, most of which aren't immediately obvious.

That statement is the end conclusion of an entire book written in the 60's by an Engineering Manager at a major US tube manufacturer. In it, he explains many misconceptions regarding tube testers and testing, and why characterizing a tube outside of the circuit it must function in will lead to frustration and likely wrong results.

[Quatro]

I'm trying to test how the tubes sound. It would be a way to compare several tubes on the fly instead of: stuffing tube in socket, letting it warm up, playing through it a bit, yanking it, next tube, repeat. By the time you swap two tubes in and out of a socket it's hard to get an accurate comparison. On this tester you switch between 6 tubes on the fly.

[SoundmasterG]

What are you trying to test?

In many cases, testing in an actual circuit is the gold standard. Everything else has problems, most of which aren't immediately obvious.

That statement is the end conclusion of an entire book written in the 60's by an Engineering Manager at a major US tube manufacturer. In it, he explains many misconceptions regarding tube testers and testing, and why characterizing a tube outside of the circuit it must function in will lead to frustration and likely wrong results.

Which book is that? Sounds interesting!

Greg

[drgonzonm]

I think I know what direction Quatro is going in.  My guess, the circuit would probably have a DC heating circuit on the tubes to minimize hum issues. 

I can think of some issues that would make it difficult, like how the oxidation on the switches affects the tone.  I could envision a multiple rotary switch. 

But his request has merit,

[Quatro]

Found it:

http://www.el34world.com/Forum/index.php?topic=11281.0

[HotBluePlates]

Which book is that? Sounds interesting!

Greg

Getting the Most Out of Vacuum Tubes, Robert B. Tomer (1960)

You can download it here. Scroll down to Vacuum Tube Theory & Circuit Design.

The book is great, but be warned: while an easy read, the full impact of some of the points he makes may take a long time before you fully realize them. Especially why a Champ may be a better tube tester than expensive and fashionable (supposedly lab-grade) tube testers.

You also get the straight dope on how to operate tubes, from the perspective of the people making the tubes!

[SoundmasterG]

Which book is that? Sounds interesting!

Greg

Getting the Most Out of Vacuum Tubes, Robert B. Tomer (1960)

You can download it here. Scroll down to Vacuum Tube Theory & Circuit Design.

The book is great, but be warned: while an easy read, the full impact of some of the points he makes may take a long time before you fully realize them. Especially why a Champ may be a better tube tester than expensive and fashionable (supposedly lab-grade) tube testers.

You also get the straight dope on how to operate tubes, from the perspective of the people making the tubes!

Thanks much!

Greg