How to choose what power MOSFETS to use?

[akb1212]

I find that the 250 and its equivalents deliver better bottom end,
but due to the large capacitance, must be driven by low
impedances on the gate (=low input impedance) in order to
sound as good on the top.

If you were bi-amping, the 250 would be excellent on the bottom,
and perhaps something like a 230 type would be good on the
top.

Hey, thanks for confirming this! That was exactly my plan, but for quad amping .

Only one problem I can see if using IRF parts..... What p-channel device to use in the X???

After all, it seems better to use the pure X-topology for pure bass amps in the several hundred watt range (after all, even if it is cold in the winter here in Norway electricity is getting really expensive lately).

So, anyone know of a good complimentary to 250???? Or alternatively, how do I calculate how many 240's to equal one 250??? 2 9240 for each 250 and double source resistor value (to make each device carry half the current) on each of those? Would there be a point in using larger devices if only possible on the n-channels?

Hmmmm, I took a second look at The Zen variation Part 1 and found that paralleling of devices is as good *** using larger devices in the frequency range I want (my horns only go up to 125 Hz).
But then again what is the point of doing it on one phase alone. On the Aleph-X of course there is a point....
I'll try it on my low-mid amp

But using more smaller devices on the top is at least no problem I'm still even thinking og going for TO220 ones here...... at least for testing. Not many devices anyway, so no problem if one fails

Anders