12v Triggered Surrounds

[Lindahl]

A video processor I received after my last company shut down has two 12v triggers. As a software engineer, I can program these (and the video processor) however I want. I was thinking about making some multiway surrounds that can be switched using these triggers from a remote control, similar to these energy speakers:

http://www.energy-speakers.com/v2/products/product-page.php?id=14

Not sure if I want to have the tweeter always on and attenuatable in dipole/bipole modes, yet, though. Might be nice for stuff like rain, if pulled in at around 6-10khz, to add presence, but I'm still not sure.

1 trigger -> multipole/monopole
1 trigger -> dipole/bipole

I hired Rick Craig to design my LCRs, so I plan on having him design the crossovers. He used Peerless Nomex 8" drivers as woofers, the RS150s as mids, and the Peerless HDS tweeter. I plan on using the same tweeter, and the RS180 as a midwoofer. I also was looking at the new Peerless 3" full range driver to fill out the dipole/bipole modes, unless Rick has any better options (appears to be the best option, given it's power handling capability - what does rated noise power mean - IEC 18.1?).

http://www.madisound.com/catalog/product_info.php?manufacturers_id=143&products_id=8305

Anyhow, this isn't really build thread (since I'm hiring out the crossover work). But I do have some questions. From the research I've done so far, it looks like I can use relays to perform this switching functionality. What kind of relays am I looking for? I plan on throwing around 200+ watts into this design at peak output, since I listen just below reference levels, and I'm not sure how to look at the contact specs to know whether or not they'll handle the load. I'm guessing Rick will use the 4-ohm version of the RS180, and will probably wire the full ranges for 4 ohms.

After spending a lot of time looking at relay specs, I believe these are my best option, but I really don't have a clue about how to choose relays for speaker-level applications:

http://www.sourceresearch.com/store1/quickstore.cfm?ProductID=102936&do=detail

Also, I think I know how I'm supposed to wire it all up, but I'm not sure:

The top of the relay is the input. Each side of the relay is a different output state. Each side of the crossover/driver is a different polarity (+/-).



So, in the end, I'm just looking for confirmation on the wiring diagram, and more information on how to choose relays for this application (or if someone knows of some good relays to use). Even though this isn't an open-source design, I figure you guys wouldn't mind me posting my questions, since they can apply to this sort of surround speaker, no matter the crossover/drivers.

[servicetech]

Just about any standard size relay will work for speaker applications, just don't switch modes at high power levels. It's the arcing during the switch that kills relays, not the amount of current while they are running. High power relay switching probably isn't very good for the amp either...

[Lindahl]

Just about any standard size relay will work for speaker applications, just don't switch modes at high power levels. It's the arcing during the switch that kills relays, not the amount of current while they are running. High power relay switching probably isn't very good for the amp either...

Thanks. I guess my only other concern about the relays would be, how do I choose one that won't degrade audio quality? Or do I not have to worry about that?

Oh, and for those that don't have an IR 12v trigger and want to do the same thing, Xantech has one:

http://www.xantech.com/products/controllers_switchers/cc12.htm

[Dennis H]

If you want an already engineered and tested solution, Chuck did a thread about using solid state relays.

http://www.htguide.com/forum/showthread.php4?t=22378

[servicetech]

Keep in mind that most amps just use standard relays internally to switch the speakers and operate protect circuits. A mechanical relay is just a switch operated by a voltage instead of by manual control. I suppose you could get a relay with gold contacts but I doubt you would hear an audible difference.

I don't think a solid state relay would work well for audio signals. Most are designed for line voltage applications.

[Dennis H]

Nevermind.

[kevmurray]

The main reason solid state relays wont work for audio applications is they have a fixed voltage drop (~1v) across them when switched on. Typical listening levels have a lot of program information below this threshold and would be lost entirely. It would sound like a severe case of amp crossover distortion. I've used many types of mechanical relays for audio and they all sound the same to me. Technically speaking it should make no difference as long as the current rating is sufficient. As was mentioned, switching them at low volume levels will greatly improve longevity.

[Lindahl]

Great, thanks guys. I'll just use these, then:

http://www.smarthome.com/7278s.html

[servicetech]

Be sure to check out mouser for relays, they had great prices last time I ordered from them.