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Relay to switch between 2 amps and 1 set of speakers
Old 7th August 2020
  #1
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Relay to switch between 2 amps and 1 set of speakers

Hi guys

Could anyone recommend the right type of relay I could use to make a speaker switch to switch between 2 amps and 1 set of speakers. I’m An electrician but never really dealt with electronics so would love to get some of your guys knowledge ?

Thank you in advance
Old 7th August 2020
  #2
Quote:
Originally Posted by Skeltonmfc View Post
Hi guys

Could anyone recommend the right type of relay I could use to make a speaker switch to switch between 2 amps and 1 set of speakers. I’m An electrician but never really dealt with electronics so would love to get some of your guys knowledge ?

Thank you in advance
Mono or stereo amps?
Old 7th August 2020
  #3
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Hi sorry stereo
Old 7th August 2020
  #4
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solid state or tube?
Old 7th August 2020
  #5
If solid state you will need a 4 pole double throw relay. Somewhere between 5 amps and 15 amps depending on the wattage of the amplifier. Here are two good resources. https://www.soundonsound.com/forum/v...p?f=24&t=58529 and https://www.diyaudio.com/forums/soli...ker-relay.html. If you have as tube amp you will have to use a different configuration due to tube amps need to be "loaded" at all times. If more questions let us know.
Old 7th August 2020
  #6
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It will be used with a variety of multi room amplifiers such as https://www.rticorp.com/ad-8x-distri...io-system.html and https://www.soundimports.eu/en/aryli...hoCnxIQAvD_BwE
Old 8th August 2020
  #7
Quote:
Originally Posted by Skeltonmfc View Post
Both seem to be "solid state" so a 4PDT relay should be fine if you are switching stereo pairs. If mono a DPDT relay would work just fine. Lots of schematics on line if you need one. Best of luck!
Old 10th August 2020
  #8
Switching inputs is not a problem. Switching speaker outputs has the potential to fry the power amp stage, especially if it's solid state and an input signal is present.

One way to do it is with a switch sequencer.
1 - disconnect amp 1 input from the signal source and tie it to ground.
2 - switch speaker from amp 1 to amp 2
3 - disconnect amp 2 input from ground and connect it to the source.

Note that, whichever amp is not being used, should have it's input grounded.

It could be done with a stepping relay, though it would probably be cheaper to do it electronically.
Old 10th August 2020
  #9
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kludgeaudio's Avatar
 

You have two choices. Either you buy whatever contactors graybar has on sale this week which have wiping contacts, or you buy something with silver or gold contacts. With big electricity, the contacts arc when they open or close, but with small electricity if schmutz builds up on the contacts it will form a semiconducting layer that is a problem. The two solutions for this are to use contactors that scrape the contacts when they are cycled, or contacts and switches with precious metal contacts (which are not that expensive). If you use those ubiquitous ice cube relays, order the precious metal option.

Something like this is fine: https://www.amazon.com/Idec-RH2B-UAC.../dp/B005T5J5NO

Ampex tape machines use plug-in relays for the transport and for routing audio and they all look the same but they have different part numbers because they have different contact materials. People swap them and then stuff stops working because the audio relays can't handle the current of the motor and the motor relays get dirty and stop passing audio.

As mentioned before, don't leave a tube amplifier without a load on it. (That's the case for a few very old solid state designs too, which use output transformers). Doesn't need to be a super load, a 10W 50 ohm resistor is enough. Just make sure the amplifier always sees a speaker or a resistor.
--scott
Old 10th August 2020
  #10
Not recommended for several reasons, another is crosstalk into the line level cabling. Use a line switcher and a dedicated amp for each set of monitors.
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