27-12-2016, 01:33 AM
I have been trying to find about differences between the Mullard ECH81 and the Rohre ECH81. I found that the Rohre standardises with a 33 K feed to oscillator anode. Certainly in the Valve Museum cover of the valve this resistance is shown. Then I got to looking up the Mullard data in my Butterworth book. It only lists the Mullard. Of course, a few weeks ago I didn't know this distinction existed. I'm also interested in the 6U8A which is also a mixer (RCA?) Anyone know of any differences with ECH81 even with regard to audio tone?
