Switching loudspeaker with relay

quietdragon · 2nd November 2011, 01:52 AM

I am looking for some design advice for the selection of an appropriate relay and design strategy.

I'm planning to build a circuit to intercept a remote trigger signal and use it to switch a pair of loudspeakers, before passing the signal on to a power amplifier so that I can silence a power off discharge pop that I find annoying.

Does it make sense to switch between the loudspeakers and a dummy load so that the amplifier has somewhere to discharge to ?

When switching, does it make sense to try to use a make-before-break relay so that the amplifier always sees some kind of load when switching ?

gmphadte · 2nd November 2011, 04:32 AM

Use normal relay and connect as shown.

Gajanan Phadte

Wingco64 · 2nd November 2011, 01:33 PM

My recomendation would be not to put any contacts in the audio path as this would create more problems later, with relay contacts. I would suggest what Morden Short did with there speakers, and put a themistor across the input of the speakers. There will be some heat generated but you are less likely to blow your speakers up. will always be some sort of trade off. What Amp are you using, there may be a fix to stop the discharge. Are you able to turn the speakers off on the amp?

quietdragon · 2nd November 2011, 01:44 PM

Quote:

Originally Posted by gmphadte

Use normal relay and connect as shown.

Thanks for the diagram.

Would you recommend a make-before-break relay ?

AndrewT · 2nd November 2011, 03:42 PM

Look at the Thread where mosFETs replace the mechanical relay.
Look particularly at why the relay solution was being rejected.

Wingco64 · 2nd November 2011, 04:24 PM

If you are intent on using a relay to switch off the speakers, then I would suggest using a solidstate relay 34.81.7.024 SPST 2A relay. about £11.00

quietdragon · 2nd November 2011, 04:52 PM

Quote:

Originally Posted by AndrewT

Look at the Thread where mosFETs replace the mechanical relay.
Look particularly at why the relay solution was being rejected.

Thanks for the pointer. I'm not sure which particular thread you are referring to.

Do you mean this thread ?

AndrewT · 2nd November 2011, 05:46 PM

Yes.
The last post points to another.
MosFet Relais

You can also use these as rail fuses/switches and as crowbars.
Might be worth reading about crowbars as well, to get a feel for what can be done without a mechanical relay.

Bonsai · 3rd November 2011, 04:46 AM

Relays are out. SSR based on Mosfets are in.

My PCB's arrive on Saturday, and I'll assemble and start writing the code hopefully by Sunday.

2nd November 2011, 01:52 AM	#1
quietdragon diyAudio Member Join Date: Jul 2008	Switching loudspeaker with relay I am looking for some design advice for the selection of an appropriate relay and design strategy. I'm planning to build a circuit to intercept a remote trigger signal and use it to switch a pair of loudspeakers, before passing the signal on to a power amplifier so that I can silence a power off discharge pop that I find annoying. Does it make sense to switch between the loudspeakers and a dummy load so that the amplifier has somewhere to discharge to ? When switching, does it make sense to try to use a make-before-break relay so that the amplifier always sees some kind of load when switching ?

2nd November 2011, 03:42 PM	#5
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Look at the Thread where mosFETs replace the mechanical relay. Look particularly at why the relay solution was being rejected. __________________ regards Andrew T.

2nd November 2011, 05:46 PM	#8
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Yes. The last post points to another. MosFet Relais You can also use these as rail fuses/switches and as crowbars. Might be worth reading about crowbars as well, to get a feel for what can be done without a mechanical relay. __________________ regards Andrew T.

3rd November 2011, 04:46 AM	#9
Bonsai diyAudio Member Join Date: Aug 2006 Location: Taipei, Taiwan	Relays are out. SSR based on Mosfets are in. My PCB's arrive on Saturday, and I'll assemble and start writing the code hopefully by Sunday. __________________ bonsai http://www.hifisonix.com/

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2nd November 2011, 01:33 PM	#3
Wingco64 diyAudio Member Join Date: Jul 2010	My recomendation would be not to put any contacts in the audio path as this would create more problems later, with relay contacts. I would suggest what Morden Short did with there speakers, and put a themistor across the input of the speakers. There will be some heat generated but you are less likely to blow your speakers up. will always be some sort of trade off. What Amp are you using, there may be a fix to stop the discharge. Are you able to turn the speakers off on the amp?

2nd November 2011, 04:24 PM	#6
Wingco64 diyAudio Member Join Date: Jul 2010	If you are intent on using a relay to switch off the speakers, then I would suggest using a solidstate relay 34.81.7.024 SPST 2A relay. about £11.00

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