I have noticed that many of the amp designs at the 18 watt forum utilise a diode network to minimise crossover distortion with EL-84 valves.
It seems a popular mod to minimise buzziness in distortion, that seems like a good idea. Has anyone tried it in a Liverpool or Rocket amp?
It doesn’t seem like a bad idea to me.
Any thoughts?
Paul Ruby mod to Rocket and Liverpool amps?
Moderators: pompeiisneaks, Colossal
Paul Ruby mod to Rocket and Liverpool amps?
Yours Sincerely
Mark Abbott
Mark Abbott
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Re: Paul Ruby mod to Rocket and Liverpool amps?
I recently did it to a 2xEL84 amp. When cranked, that amp’s PI got super lopsided and the cathode voltage would swing way high, like double the idle. I put the back-to-back 16v zener/1n4007 across the bias splitters and a 15v/5W across the cathode resistor/cap. These were the lowest values I had on hand. It certainly cleaned it up on the ‘scope and it did sound a tiny bit less buzzy (it wasn’t bad before). But it wasn’t a huge difference. I need to try slightly lower voltage zeners like 12v/13v.
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Re: Paul Ruby mod to Rocket and Liverpool amps?
Thanks for your observations and sharing your experience.
Yours Sincerely
Mark Abbott
Mark Abbott
Re: Paul Ruby mod to Rocket and Liverpool amps?
I remember seeing this on one of the 9 Trainwrecks I owned. Most didnt have the diode mod. The Express bias settings and even brand of El34's would affect crossover distortion..