View Single Post
Old July 21st 19, 08:36 AM posted to
Phil Allison[_4_]
external usenet poster
Posts: 499
Default Best new EL84 tubes?

Big Bad Bob wrote:
> > ** FYI, I have a prototype 2x EL84 output stage here that
> > delivers over 50 watts with low THD and no overheating.
> > The trick is to use a split supply of 325V and 650V for
> > screens and plates respectively.

> probably works ok for hi-fi but I wonder how it would handle output tube
> overload distortion for a guitar amp...

** Just fine, the European made amps that used a similar set up were instrument amps. Clipping the output wave causes low plate dissipation but high screen - keeping the screen voltage down helps a lot.

> I guess you could run clipped sine waves through it to find out. I used
> to test power amplifiers under conditions like that by dunking a
> somewhat-high-wattage 8 ohm resistor (tied to speaker outputs) in a
> glass of water. It's funny to watch it boil the water just a bit...

** I use a bucket of water with a pair of 100W, tubular ceramic, 8 ohm WW resistors. A simple switch box allows 4, 8 and 16 ohm loads. Copes with 2kW fine.

..... Phil