El84

I guess that some folks have been wondering what I’ve been up to the last month or so. Well, I’ve been trying to take it easy to let a shoulder injury heal. If physical therapy can be considered “taking it easy”. In the last month I’ve learned all about labrum tears. However, today something arrived in the mail and that means it’s time to get back to work.

As I said the other day, “It is my estimation that the EL84 would greatly benefit from a lower percentage UL tap transformer.” Whereas there is much to be learned from the current data set taken with the Edcor GXSE10-5K transformer, I have decided that a different configuration needs to be tested as well.

So I’ve spent the last week looking at the data from the initial effort. I’ve retaken some data, analyzed the performance and setup, poured over data sheets and characteristics curves, listened to some music at a lot of different operating points, and I’ve drawn some initial conclusions. And I must confess I’ve gotten some interesting surprises.

Well, all the data for the aforementioned optimization is collected and in the computer. I’ve been chewing on the data and my notes for the last couple of hours and it’s safe to say, there is a lot more here than first meets the eye.

We’ve had a bit of a cold and rainy snap here which has prevented me from getting to the chassis work for the new 807 amp. But that doesn’t mean I’ve been totally idle.

I’ve finished modifications to my test jig to allow the testing of the 6BQ5/EL84. It’s really a shame that so few other 9-pin power pentodes use the 9CV pinout. The 6CW5/EL86 is the only other really common one.

Just in case anyone was wondering, I have made a decision about my next power tube optimization.

So I’ve been reviewing EL34/6CA7 data sheets preparing for an EL34 SE-UL optimization study like the two I’ve done before for the 6V6 and 6L6. However, I’ve run into a little snag.