Quote:
I know both the EF80 and EF184 are popular tubes with builders.
|
Mainly cos the EF80 is cheap and the EF184 cos it's mentioned quite often in thread's. The 184 comes up a lot I think cos it was used in a lot of scope front ends, it's also developed a self perpetuating self affirmation cult due to all the threads on it, not to say it's a "bad" valve.
That tone control circuit you attached is touchy, as regards gain as Robert says, I tried modding it using an ECF82 after the tone control to get extra gain in one valve base, no go. As per the author's schematic it works, mess with the gain and it's essentially an attenuator. In my case I added an ECC82 gain stage, 47k Ra, 1m grid leak. 1k ish Rk after the published circuit. You could use a CCDA line stage though.
Andy.