2-ohm stable amplifier PCBs or kits available?

[sreten]

OK, ignoring BSD.

You are correct about the voltage sensitivities of the two arrangements.
Neverless they have identical power efficiency, as the +6dB
case draws 6dB more current than the 0dB case.

IMO its a lot simpler, and a little safer to pad the tweeter
back to 92dB than running the two mids at 98dB / 2 ohms.

The tweeter ends up with the same current : A 300W/2R
amplifier will only manage 75W into 8R, i.e. the tweeter.

If the tweeter has its own amplifier then sensistitivities are
equalised by adjusting the gain of the seperate amplifiers.

And all that matters is real efficiency dB/Watt, not dB/V.

sreten.

P.S. there is no need for the 4 amplifiers to have equal power
rating and 300W per amplifier for midrange is seriously too much.

You need something like 100W+100W+50W+25W.

But is does depend on the power efficiency of each driver.

Note that 4 100w amplifiers used in an active 4-way have a
total voltage swing capability equivalent to a 1.6KW amplifier
driving a passive 4-way.
At 300w each this equals 4.8kW !

sreten.

[sam9]

If you are wiring your speakers to get a nominal 2 ohm load, isn't there a good chance that at some frequency, it will be lower?

Many protection circuits built into the output section of amplifiers will be active at this low a load. Even if you don't hear anything unpleasent, the protection will limit the power the amp delivers wich may negate any benefits you intended by trying to wire the speakers to increase sensetivity.

On top of that, due to a characteristic called "beta droop", driving a 2 ohm load will roughly quadruple the distortion figure for the amp as comparred to an 8 ohm load. That may be ok if the distortion figure is very low to begin with, depending on the amp it is quite concievable you would notice it at high frequency peaks.

I think your plan of action may be creating many more problems for you than it solves and may result in an overall listening experience that will diappoint you.

[pkpickard]

You all have convinced me. Sam, the nominal load would be closer to 3 ohms but yes, it would dip to 2.5 at it's lowest. I will wire up an amp for the tweeter, and an amplifier each for the two mids, plus an amp for the woofer and and amp for the subwoofer. An active 4-way with 5 amplifiers... this project could get a little over the top.

So now I just need to go about generating 4 2-channel amplifiers with 50-100WPC into 8 ohms in a single enclosure. (I already have a Carver TFM-42 I can use for the subs.) Looks like it's time to start considering P3A and gainclone PCBs....

[sam9]

"Looks like it's time to start considering P3A and gainclone PCBs.".
Don't forget to look at Marchand, AKSA, Ampslab (and even Seal Electronics if you can deal with a bit more complexity)

[BrianGT]

Here is a proposed solution to this problem that I started looking at today at lunch:
http://www.diyaudio.com/forums/showt...209#post352209

--
Brian