How to use Elk Relays as speaker switches?

Hello, I am a newbie at home automation, and originally I was only going to do lights on the Elk with insteon. But once I read more and more about the vast possibilities, there was no going back!

Here's what I am trying to acheive, and I would appreciate any suggestions in how to do it.

Currently I have a Sonos player going into a 6 speaker selector with push button switches, going out to ceiling speakers in six different rooms. I would like to switch these speakers with the elk m1g. I am a faint idea that I can use the Elk relay board (Elk M1XOVR or Elk M1RB) to achieve this... but how?

I found this thread back in 2007 but I don't really understand how to wire it up. I can't post links yet but the thread title is "Elk Relay as Speaker Switch".

Any help will be much appreciated! Thanks!

I'll help you out with the link - I think you're referring to this one:

http://www.cocoontech.com/forums/index.php?showtopic=7143&st=0&p=60980&hl=+elk%20+relay%20+speaker%20+switch&fromsearch=1&#entry60980

What makes it so simple in that particular post is that the OP is switching from one set of speakers to another - not changing the number of speakers connected. The most important thing that your current speaker selector SHOULD be doing is the impedance matching.

If you're not familiar with the concept of speaker impedance you'll want to read up.
Example - you have 1 speaker hooked up - it's 8Ohm (generally for household speakers). That's fine for the amp - but say you connect a second speaker - you can either connect it via parallel or series - Parallel will drop it down to 4Ohms; Series will bring it up to 16 ohms. Your amp will work best in a set range - typically 4-8Ohms for household receivers. Too low and you'll cook it.

That doesn't mean it's not possible though - I would imagine others have better thoughts on the matter - the trick is going to be keeping the impedance the same regardless of how many speakers are on or off at any given time. I'm sure this can be accomplished by wiring something inline on the NO contact when the speaker is off - hopefully some of those better in speaker/electrical engineering in the room can chime in.

Thanks!

Actually, what I was thinking was to put the relay between my speakers and the speaker selector. All the manual push button switches in the speaker selector would be left "ON" permanently. The speaker selector will do the impedence matching like it normally would if the circuit is complete. Then I put the elk relay in between the speaker and the speaker selector. If the elk relay is on, the circuit is complete and the speaker turns on. If the elk relay is off, the circuit is broken and the speaker turns off. This should theoretically work right?

If yes, the my question becomes how to put in the relay. I have stereo speakers so 4 wires => L+/L-/R+/R-. If I do L- output from speaker selector => elk relay => L- to speaker, then the elk relay should turn on and off the left channel of the speaker. How do I put the elk relay in between the speakers and the speaker selector that switches both channels? Can I combine L-/R- output from speaker selector => elk relay => split back to L-/R- to speaker?

Not to be Nancy Negative, but before you get set on doing this, do a little Ohm's law math for your application to make sure you're within the ratings of the relays.

Remember that your audio is technically AC with DC coupled in there.

The Elk relays do have a NC and NO side, so you could put a resistor across the other side to keep your impedence consistent on or off. For a 6 stereo speaker setup you would need 12 relays. You would probably need to run groups of speakers in parrallel to get the proper impedence.

Like two groups of 3 speakers in series running parrallel to each other for each channel.

I don't really know how a speaker selector is setup to know if running into the elk relay after it comes out of the speaker selector would work properly.

This would take some good testing with the speaker selector to see what it's doing when the speaker is on vs. off; I'm sure it's doing something in the circuitry to keep the speakers balanced whether there's 2 speakers on or 12. I doubt it's as easy as just putting relays after the selector - would be cool though.


As for the relays though, I'd look at the Elk924's along with the voltage only outputs from either the onboard or the M1XOVR - reason being they come in individuals or sets of 4 attached (scored so they can be separated) - and each relay is a DPDT - meaning it can switch both the left and right at the same time - and connect a speaker in one position, with a resistor or whatever else is needed in the other position - for each.

I'm not talking impedance, that's an easy solution, with the exception of the size of an apppropriate dummy load. I'm talking the rating of the relay itself. As an example, an 8 ohm speaker load @ 100W will have 28 volts @ 3.5A going to it. 1/2 the A rating of a 924 itself.

If your amp itself is rated in RMS power, you're already exceeding the load, let alone any headroom peaks the amp will hit for a short period of time.

By leaving the selector with all the outputs ON and switching the loads on the back side, you're negating the impedance matching of the unit, which would most likely be done via the pushbuttons.

I would tread lightly, as you are looking at the potential of letting out a lot of magic grey smoke on multiple components.

Thanks for all the suggestions so far!

Why would there be a problem with impedence matching by putting a relay at the backend? The unit I have is a SIMA SSW-6, which is an unpowered speaker selector with impedence protection. Since the unit itself is not powered, it seems to balance the speakers only if there is a complete circuit - speakers making all four correct connections plus the push button in.

If I put in an elk relay in line between the negative terminal of the speaker selector and the speaker, and it's in the open state, how is it different from connecting just the positive terminal of the speaker but not the negative terminal of the speaker?

This may be overly simplistic but I basically just thought of the relays as an electronic way to break the negative terminal connection to the speakers, thus no sound. If the circuit is not complete at the speaker, it's not drawing any current, and thus it should like it doesn't exist to the speaker selector.

I may be completely wrong as I have a very limited knowledge of electrical stuff, so any help is appreciated. Thanks very much!

You are correct, putting a relay on one of the speaker wires after the selector would effectively be the same thing as unplugging the speaker (you could interupt the pos or neg, it would make no difference). You would have to consult the speaker selector's manual to see what impact, if any, that has on the speaker selector. Years ago I had a cheapo radio shack speaker selector and if you turned on a speaker that didn't exist, it would shut off other speakers (which were appearantly put into series with the missing speaker by the selector). I haven't messed with an external manual speaker selector in decades so I don't know how they are typically put together now days.

And the 8 relay board that Elk sells (m1rb) is plenty well rated for speaker power levels.

In my house I have in ceiling mounted speakers for music in some rooms. I use an ELK-924 relay to switch some speakers from the stereo to the M1's output 1 for voice announcements.

I wrote a Rule:
Whenever AudioAmp turns on
Then turn relay output on

Whenever AudioAmp turns off
The turn relay output off

I just completed this tonight, and it was a success. I wired 12 total channels from six pairs of speakers in six rooms into 12 relays, using m1xovr and m1rb. I elected to show only the right speaker output, and wrote rules to turn on and off the left speaker relay triggered by the right speaker.

I can now select the speakers in the different rooms from eKeypad.

Thanks for all the help / suggestions!

How did you do it? Do you just interupt the output from your speaker selector or did you create your own imepedence matching with the relays?

Lou Apo said:

How did you do it? Do you just interupt the output from your speaker selector or did you create your own imepedence matching with the relays?

Click to expand...

I placed the relay between the negative terminals of the speaker selector and the speakers, so yeah, I just interupted the output.

Galun said:

I placed the relay between the negative terminals of the speaker selector and the speakers, so yeah, I just interupted the output.

Click to expand...

So effectively your bypassing the impedance matching function of the speaker switch? You can't just remove or add speakers connected to one output without dealing with the impedance being maintained between 4-16 Ohms (in most cases - some amps have a tighter requirement). Not doing so can damage the amplifier.

Good luck and watch for smoke.

jwilson56 said:

So effectively your bypassing the impedance matching function of the speaker switch? You can't just remove or add speakers connected to one output without dealing with the impedance being maintained between 4-16 Ohms (in most cases - some amps have a tighter requirement). Not doing so can damage the amplifier.

Good luck and watch for smoke.

Click to expand...

If you use 32 ohm speakers and keep at least 2 connected in parallel you can get away with it. I actually have one install with just one 32 ohm speaker on an ELK and it works fine. Not as loud as it could be but loud enough for the application.