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Phil Allison[_4_] Phil Allison[_4_] is offline
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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.

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


..... Phil