Was wondering if any of the smarter folks on the forum could tell me if the EL38 is a compatible tube for the ZMA?  A friend has an unused quad and it got me thinking.  The recommended bias is pretty low from what I can see.  

Best,
Jon

Thank you. That was my feeling. Now I just need to figure out how to calculate the bias for this amp. I seem to remember someone posting a calculator before. Cheers.

Just in case others might try, El38s will not bias in the ZMA.  The meters stay at 0 no matter the bias settings. I let them warm up for 5 mins but didn’t want to try longer.  When I shut off the amp, as the captors were draining and the VR tubes flickered, the meters jumped up to 50 or so and stayed there briefly. I believe this indicates they were getting too much current. Although similar to an el34, I have learned that the el38 has much higher gain and needs to be biased even lower.  Makes sense.

In the tube buffer of the Lampizator, the el38 has a nice midrange for vocals but was somewhat thin on the top end and weaker in bass compared with my preferred tubes.  This is of course with unused 60+ year old tubes and presumably might improve with some break in.