Holy shmoley it worked. XLR Y stereo pair into XLR single mono with the opposite signals dropped. I'm just very annoyed that the Peavey tops have their frigg'n outputs as post-gain/volume knob. I called them today and they don't think there are any easy jumpers in there to make the outs post-knob or unity by default (so knob has no effect). The sub is still a little too quiet, even though it's a lot louder than using unbalanced from the tops, to a passive TEC sum box I've got (normally used on my computer for headphones), and then into the sub. That technique's got barely any signal at all. Tops are loud as hell even with the knobs way down, but out is so low, then 6dB down from the summing resistors. Darn.
I have no problem with volume obviously going unbalanced separately: master to the tops, booth to the sub, or vice versa. But I can only do short runs with that.
I was thinking using Y-cables from the single XLR from my main interface/controller, but I'm pretty sure that will wreck havoc without that special XLR summing box from England. It won't allow the output opamps to behave with the + dropped on one side and the - dropped on the other on just one each of the Y splits.
So the solutions left are using a dedicated crossover...
or another pair of Ys with either a dedicated mixer, that passive XLR sum box ($80), or a transformer/regenerator/converter box ($50)...
or just live with unbalanced and limit my runs.
What's the cheapest good-sounding external crossover with a pair of XLR ins, mono out to the sub, and the crossed XLR outs to go back up to the tops?
It has to be substantially cheaper than just buying another sub, because with all the cables I've been trying I'm starting to lose my savings with only going with one. I could have saved cash on poles instead of tripods, short XLRs just to go from the tops to the subs, etc... and had stereo bass!
Last edited by Reticuli : 10-29-2012 at 08:36 PM.