Triode

I’ve been moving some amplifiers around today, listening to some that have been idle for a while and doing a little side-by-side comparison. And I’ve been reminded of a very important fact about amplifier performance.

There is truly nothing like the smell of a freshly wound transformer.

In my last post, I talked about the changes I’ve made to my 807 prototype jig so that I could investigate the 400v, triode strapped, plate voltage limit. Now I’ve managed to spend some time playing with the high voltage prototype power supply and my newly modified jig. As a result, I’ve learned a surprising amount about the 807 operating as a triode.

So I’ve been thinking about my next amplifier project. And I thought I had made up my mind. Then things changed… again.

I took some time this week to get several coats of oil on the chassis for the Dual Triode Test Station. Even though I’ve already used it for the mystery tube investigation and to compare some 12AU7s, it’s good to have it finally complete.

Ignoring the wood chassis for the time being, I made significant progress on the triode test jig today. I just thought I’d post a quick update. Parts are now mounted and some wiring is underway.

We’ve had a chilly rain/snow mix today at CascadeTubes so it’s a little too cold to work on the SET chassis in my unheated shop. Instead I’ve been thinking about my new triode test jig and have been going over the tube list that it covers. There are lots of tubes on the list with which I am not intimately familiar so I’ve been pulling data sheets and doing some investigations. And I’ve received some pleasant surprises!

The discussion on tube testers and their usefulness (or not) got me thinking about my own tube testing needs and how I go about it. I already have a solution for octal power tubes with the 7S base pinout which I’ve mentioned before. But what about those ubiquitous signal triodes I seem to use in almost every project? What should I do about them?