Best new EL84 tubes?

> ** 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...

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...

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.

https://www.ebay.com/itm/8-ohm-100-W...-/201153517823


..... Phil

The EL84s I like the best are the new old stock Soviet tubes from the 70s and 80s.They are starting to get a little scarcer on ebay,but they are still not that expensive.