> I lose the advantage of not using something here that has to throw off photons.I understood that. I too resent the "waste". But I'm not coming up with any way to use that waste, not which _I_ like. I have no real objection to any of your plans, and no real preference. I sense you don't have a favorite either. Either we both dumb, or there isn't a "great!" solution.
What we "obviously" want is a way to get ~~2V at set current from 18V-10V with "no" waste. A rectangle wave with 10% duty cycle can be very low voltage waste. Add a coil and adjust frequency to get low current waste. Same as a Switching Voltage-Regulator, only different. And awful small for the ready-made switcher chips. And major designer-distraction, when the focus should be on the audio.
If you would allow the pull-down CSSes to drop-out on huge negative swings: LED up from Neg rail. Two CSS JFETs from opamps to LED. 1mA pull-down per channel gives 2mA LED current. Assuming 2V LED and 1V FET and 9V rail, pull-down works to 6V peak, "fails" for the largest peaks, but we surely clip by 8V or 7V. If a little more signal gives total loss of accuracy, I'm not inclined to care if the pull-down "only" works to 6V, and after that there may be an A-B crossover. In real speech/music this should be a very rare event, unless you have pushed into frequent clipping then so what?
In extreme clipping, the LED could dim; so what?
I'm quite sure battery life will be better with LARGE caps, either in/out or if you must pretend "capacitorless", then swamping the rail-splitter. With the pure active rail-splitter, most actual signal power is dissipated in the splitter. With ample caps, this power is re-cycled to the next half-wave.
I preached that before and got no takers. The experiment seems too simple to avoid. Devise a consistent source, such as a CD on Repeat. Buy a 10-pack of 9V batts and select four of equal voltage. Load an amp, play until batteries sag to say 8.0V. Note time. Then build-out the rail-splitter with 100R, add two 1,000uFd rail-caps, change batteries, repeat the run. I predict the splitter will run cooler and the batts will last longer.
Yes, 2x1,000uFd is "big". Less will work. And if indeed the batts last longer, is that worth something? Maybe a smaller battery, or not carrying spares?
Bass crosstalk will rise. There isn't a great answer for that. Except wiring single-ended with output coupling caps. And that violates much dogma. Or 4-wire headphones, which is not generally done.
I realize you are doing an incremental improvement, not a radical re-think. I'm just jabbering with post-Flu false energy.
posted 02-10-2009 01:37 AM CST (US) 
