I've built one Bottlehead/Speedball Crack amp and have been thinking of trying out a solid state project (maybe an M3, or a beta22 if I'm crazy, though I should probably start with a mini^3 for sanity sake). I've been reading up on AMB and Tangent, etc, and I think I'm at the point where I know just enough to be foolish/dangerous.
I was also reading up on Meier's concept of active balanced ground (http://www.meier-audio.homepage.t-online.de/concerto.htm , also on the symphony page) and thought to myself: "hey, I think I can do that"... famous last words.
From what I can tell, I would apply a -(L+R)/4 to the left, right, and ground channel. So basically, working on a three board setup like the beta22, my new inputs (denoted with *):
L* = L - (L+R)/4
R* = R - (L+R)/4
G* = - (L+R)/4
Does this look about right?
That all said, I'm not actually sure *how* to implement it. I know I can make a simple summing circuit by using a couple resistors...
... then taking a quarter of that output (umm, run the output off 4 equal resistors in series and tap one resistor?) to get my (L+R)/4 value. Then use another couple summing circuits to get your L* and R*. Except I don't know how to get the negatives, and I think simply flipping the +/- would be a bad idea, unless maybe I just ran resistors off all 4 wires
But, I know there are issues with attenuation of signal when you start splitting and combining things willy nilly. A summing circuit loses 6 dB? That's sort of a quarter right? er...
So assuming anyone was able to follow that mess, am I completely off my rocker?
Edited by Armaegis - 12/26/10 at 2:18pm