Ah! It looks like I should build circuits for all of his flavors.Thanks Wyn!
If you're talking about the .asc file from the Leach web page, that's for the Common-Emitter circuit, not the Common-Base that I built (he didn't provide .asc files for the 2 Common-Base circuits). So your reference to "change R1 to 75 and R4 to 10k" may not be appropriate to my build.
I don't have the means to take real measurements, so I used the "Mark-I ear" method. With everything turned on and warmed up, needle lifted, turned the volume to maximum. Had to get my ears to within 6-8 inches of the speakers to just begin to hear hiss (and a little hum). An old analog RS SPL meter wouldn't even register 60dB w/mic 1" from either tweeter or woofer panels.
All-in-all, I'd say thats very quiet!
bypassing the degeneration R to
Will still do the AD797 though, and see how they stack up against one another.
The common base design is far more dependent on the exact characteristic of the transistors than the common emitter, and the miller capacitance of the input transistors will appear across the input of the common emitter design, but other than that the audio performance should be very similar.
The load R should also be scaled about the same to provide the increased gain.
I'll find some time over the next few days and do a full simulation of it.