Switching multiple 5.1 speaker systems?

Hi All,

Anyone know of a design for a switching box that will let me switch between 3 different sets of 5 speakers from the one amp? I will have an array of 15 speakers and want to be able to switch between any of the 3 sets of 5 so I can demo each of the 3 arrays in turn. I currently use a manual set of switches but this gets pretty tedious when doing A-B comparisons!

I assume I need something like the soundboards used by Car stereo shops but I haven't seen a DIY design anywhere for them.




2002-01-07 6:02 pm

I'd try a dpdt relay for each speaker.

Using one speaker (LF) as an example:
-take the o/p from LF amp to a terminal block, soldered or screwed. Then take 3 individual wires each, from 'hot' and 'gnd'. Take one from each and wire to relay 'common' terms, and then output from relay n/o terminals to LF # 1. Repeat for LF #2 and LF #3. For LF # 3 wire some 20-50W (or bigger) power resistors across relay n/c terminals . This way your amps always see a load, even if you have a power out on the relay supply. Cheap insurance as some receivers are not stable with no load, and might oscillate themselves to death in this situation.

-make sure the relays you select have a current rating greater than the speakers max current draw at full power.

-do the same for other 5 sets of speakers (18 dpdt relays in total)

-make or buy DC PSU with enough current capability to take say 12 relay coils, to account for switching transients. Not strictly neccessary, but easier/cheaper to built it this way first.

-If you have a sp3t switch that will take the current load, wire all 6 coils for speakers # 1 to switch position 1. Repeat for set #2 and # 3. If your switch doesn't have the current rating, get one that does or use 3 driver transistors, taking their base drive from the switch instead.

Hope that's clear to you. I can't get my drawing program to load to draw you a pic. Maybe someone else will be so kind.

It's as clear as mud. I figured it would have to be some sort of arrangement like this, I just wasn't sure what the right way to do the relays was. For some reason I was thinking that each relay would have to handle 3 speakers, ie a TPDP (if there even is such a thing) but of course that's stupid as each "channel" in the system needs it's own relay and there are 15 channels in the system.

Thanks again, I'll go order a bunch of suitable relays and start playing with a box!