[stereocilia]

I was looking for a way to sum a stereo signal to mono to be sent to multiple passive subwoofers and I found this. It looks like it would work: http://www.parts-express.com/rolls-db14b-av-presenter-stereo-patch-direct-box--245-1012

EDIT: NO, it won't work. The LF cutoff is 50 Hz. No good.

There's also this one: http://www.parts-express.com/switchcraft-319-audiostix-35mm-stereo-to-terminal-block-mono-a-v-di-with-20db-pad--245-5304#lblProductDetails
I know I can't just use a y-cord. Suggestions appreciated.

[Phil A]

Does this work?  http://www.mcmelectronics.com/product/MONACOR-SMC-1-/50-9042

[Speedskater]

Subwoofing in Mono :: RaneNote:

Why Not Wye?
Dennis Bohn, Rane Corporation
RaneNote 109 written 1991; last revised 4/04

    Splitting Signals
    Subwoofing in Mono
    Unbalanced Summing
    Balanced Summing
    Output Impedances

http://www.rane.com/note109.html

[srb]

Does this work?  http://www.mcmelectronics.com/product/MONACOR-SMC-1-/50-9042

If the stereo outputs of the preamp are in parallel with a second set of stereo outputs (unbuffered), I wonder if the lowish 4.7K ohm input impedance would have an effect on the main preamp outputs' stereo separation?

Steve

[Phil A]

There is also stuff like - https://www.edcorusa.com/s2m

[stereocilia]

Thanks for all the replies! The concern about reduced stereo separation is something I hadn't thought about. is there an audible effect in the mains when a stereo to mono thing is used?

[stereocilia]

Maybe it's fine just to use half the subs on one channel and half the subs on the other, then I can skip the summing circuit. In other words, is the benefit of a monaural signal worth the L/R crosstalk from the summing circuit?

[jtwrace]

Suggestions appreciated.

Behringer DCX is probably your best bet.  Remember you want to run the speakers full range and "blend" the subs into the mains.  So your pre will need dual outputs, one for main speakers and one for DCX.  Then you would use 3 or 4 XLR cables depending on how many subs you have and feed them from the DCX.  Also important to make sure that you have the ability to tune each sub including polarity and delay. 

[stereocilia]

Sounds like the dcx might be best; thanks Jason. I should check out the mini dsp, too.

[Rusty Jefferson]

Not sure about your set up, but there are a couple dedicated units for this task.

Here's the JBL BX63(A) crossover.  Designed to be used with a couple particular driver/cabinet configurations.  You can read about both the crossover and subs here;
http://www.lansingheritage.org/html/jbl/reference/technical/1983-subs.htm

Sumo developed a competing product, but it doesn't sum, it's stereo.  Edit: Sorry, it does stereo or summed mono.
http://www.stereophile.com/content/sumo-samson-subwoofer-amp-delilah-crossover#6Lw7eTfiMsEhsybt.97

If your preamp has 2 pairs of outputs, and can drive 2 amplifiers, you can run the full range speakers direct, and just feed the LF through the crossover.  No problem using a "Y" on the BX63A for 2 LF outputs.  Most of the JBL and Sumo units are ready for rebuilding.  I've had to rebuild both of mine.

Also, Marchand makes dedicated crossovers that would apply.
http://www.marchandelec.com/wm8.html

[John Casler]

If you can find one, the NHT X-2 is what you might look at.

[Russtafarian]

Provided your preamp has an active buffered output, you can build a summing Y cable.  Simply solder a 1000 ohm resistor in line to the center pin of both the left and right RCA plugs and sum the left and right hot conductors to the center pin of the mono RCA plug.  This creates a stereo to mono passive mixer. 

This approach may not work well if you use a passive preamp and rely on the current drive of your source components to feed your amp and sub.

Russ

[stereocilia]

I have a Bryston BP26 with balanced and single-ended outputs. Obviously it buffers the output from the source, but are the outputs buffered from one another in the same channel? So, I still wonder how bad it is to just use the left channel for one sub and the right for the other. I feel like that's bad form but I really don't remember why. I hope I didn't make that up.

The Behringer DCX has enough flexibility, for sure, but I think one of the benefits of multiple subs is that EQ becomes less beneficial. Besides, that is a complex machine. I can handle it, but I'd like to avoid adding to my rapidly growing collection of things I have to plug in and program if I can. Maybe I can't.

My idea was to use a crown xls 1502 with its built-in LPF function to drive the two passive subs. Each channel seems to have it's own gain control, so that's good. I wouldn't have continuous phase control, but couldn't I just swap the +/- at the speaker terminal for +/- 180 if I needed to, yes?  That would make things simpler: Source, preamp, 2 amps, 2 mains, 3 or 4 subs (2 passive and 1 or 2 active).

[Phil A]

Also don't forget the Bryston sub x-over - http://bryston.com/products/other/10B-SUB.html

[stereocilia]

The Bryston would be great if I were not running the mains full range. I decided to go with the Mini DSP 2x4 for now. Thanks everyone!