# Relay speaker switch????



## southpawskater (Feb 17, 2010)

I saw an idea someone posted on here about using relays to switch between a pair of speakers.
So I did a little reading and researching then drew this quick diagram in paint.










My questions are:
A)	Is the concept correct in the drawing
B)	Do you think there will be noise issues from the relays?


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## minbari (Mar 3, 2011)

A) yes the concept would work. home recievers do this all the time. ever hear that "click" a few seconds after you turn your home reciever on. its relays turning on the speakers. 

B) that will depend on the quality of the relays and the quality of your toggle switch. I imagine it wont have any noise.

just a note, if you get the bosch relays that have the 87a leg on em. you can get that down to two relays


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## southpawskater (Feb 17, 2010)

minbari said:


> A) yes the concept would work. home recievers do this all the time. ever hear that "click" a few seconds after you turn your home reciever on. its relays turning on the speakers.
> 
> B) that will depend on the quality of the relays and the quality of your toggle switch. I imagine it wont have any noise.
> 
> just a note, if you get the bosch relays that have the 87a leg on em. you can get that down to two relays


Well now I have more questions...

With the 87a leg would I put + for speaker #1 on 87 and + for speaker #2 on 87a?

Would 87 be active when relay is not charged at 86 connection and 87a when relay is charged at 86?

Would it be better to put the relay on the negative side of the speaker circuit as opposed to the positive?


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## minbari (Mar 3, 2011)

southpawskater said:


> Well now I have more questions...
> 
> With the 87a leg would I put + for speaker #1 on 87 and + for speaker #2 on 87a?


yes


> Would 87 be active when relay is not charged at 86 connection and 87a when relay is charged at 86?


I can never remember, lol. I think it rests with 30 and 87a connected and 30 and 87 when energised.


> Would it be better to put the relay on the negative side of the speaker circuit as opposed to the positive?


if there are no passive crossovers involved. makes no difference.


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## southpawskater (Feb 17, 2010)

Thank you!


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

This is a REALLY bad idea.... 

Relays tend to cause some funky things to happen, say as the contacts come together, there is a miniscule arc, that arc, like any arc is danger in the making to speakers


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## southpawskater (Feb 17, 2010)

Can you elaborate Aaron? 
What would cause it to be a danger to the speaker?
It would be the same signal/power going to the speaker as if it was directly connected to the amplifier just on a switched circuit.
I wouldn’t be switching speakers while there was power going into the speakers.


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## ween (Mar 12, 2009)

hello,
so the switching system that a demo board uses is a bad idea? the protection relay that an amplifier uses to disconnect the speakers in case of a fault is bad also?
in thirty years of doing 12 volt, never heard of any issues.
just my two cents.
mark


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## Horsemanwill (Jun 1, 2008)

ween said:


> hello,
> so the switching system that a demo board uses is a bad idea? the protection relay that an amplifier uses to disconnect the speakers in case of a fault is bad also?
> in thirty years of doing 12 volt, never heard of any issues.
> just my two cents.
> mark


if i recall right the demo boards also have a small microprocessor as to have a "buffer period" between switching


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## ween (Mar 12, 2009)

of course, there may be a small buffer period...but there still would be an 'arc' as contacts are still being opened or closed and a signal source is present?


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## hilander999 (Jul 6, 2011)

A diod between the energizing coils stops electrical spikes to the power system, and a cap in line to the speakers would take care of any surge that might happen. Just make sure you get a cap below the working frequency of the speakers you are using.

All of this is mute if he has no intention of switching speakers while the system is operating. This can be safely done, just do your homework first.

They use relays in line to speakers to stop turn-off-pop all the time, and this is not much different. Google a bit and you will find all sorts of tested diagrams for different speaker control setups. One of the most common is to use the bosh SPDT relay to change the wiring on subs from series to paralel (2 to 4 ohms) and I doubt these "geniuses" are smart enough to turn anything off first.


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

hilander999 said:


> *A diod between the energizing coils stops electrical spikes to the power system, and a cap in line to the speakers would take care of any surge that might happen. Just make sure you get a cap below the working frequency of the speakers you are using.*
> 
> All of this is mute if he has no intention of switching speakers while the system is operating. This can be safely done, just do your homework first.
> 
> They use relays in line to speakers to stop turn-off-pop all the time, and this is not much different. Google a bit and you will find all sorts of tested diagrams for different speaker control setups. One of the most common is to use the bosh SPDT relay to change the wiring on subs from series to paralel (2 to 4 ohms) and I doubt these "geniuses" are smart enough to turn anything off first.


 
That's what I was looking for...!!! 

The info was/is locked away in the brain somewhere, I just couldn't access it.. :laugh:


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## southpawskater (Feb 17, 2010)

Thank you all for sharing your knowledge its greatly appreciated.


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