I got a quad of the EL34EH back in May or June. In between I used a quad of SED and the American Svets but since then until now, the EH have been making music in my Dyna about 80% of the time. I use them daily, so they've had a long break in period.
In the past few weeks I began to notice a change in the overall sound. These guys sound damn good now. Before, the top and upper mid was a little aggressive compared to SED but I was able to ignore it because it's an excellent sounding tube. Now after the lengthy break in period, these tubes just keep getting better. High frequency is still extended but it's much, much smoother and warmer now. Mids is also much sweeter and bass seems a little warmer. I love it. The only way to describe the differece is that at first they sound more ss but very tubey after break in.
So if any of you ST-70 owners or EL34 based amp owners are using them, keep breaking those bad boys in. You'll love the result. If you buy them, give them plenty of time to run and be blown away.
I know I'm not suppose to be buying new toys yet but I got a raise at work, I quit smoking(saving $ there), so I deserve something new. I just ordered a quad of Chinese Shuguang EL34B. If I get the package before the parents, I'm safe:D. I know that there's been a lot of negative comments on Chinese tubes but after doing a lot of research at the asylum, I came across several posts where the owners are really diggin them so I thought I should give them a try. I'll report back on their sound quality when I receive them.