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Relays that are "audiophile" grade

starfly

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I plan on building my own auto-switching input selector, which will use a 12V trigger signal to switch between my AVR or Streamer+DAC sources, which then get fed to my poweramp. The reason I'm doing this is that off the shelf solutions are either too expensive, or purely manual. And since I'm lazy, I don't want to have to get off the couch to switch inputs :)

What are good relays I can buy that have very minimal crosstalk? My research so far shows that can be a problem with some relays.
 

MakeMineVinyl

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I plan on building my own auto-switching input selector, which will use a 12V trigger signal to switch between my AVR or Streamer+DAC sources, which then get fed to my poweramp. The reason I'm doing this is that off the shelf solutions are either too expensive, or purely manual. And since I'm lazy, I don't want to have to get off the couch to switch inputs :)

What are good relays I can buy that have very minimal crosstalk? My research so far shows that can be a problem with some relays.
The best way to avoid crosstalk is to keep impedances low and use separate relays for the left and right channels. You should use inert gas filled gold contact relays for audio switching.
 

DVDdoug

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Line level signals aren't much of a problem. Resistance isn't an issue and I doubt you'll have crosstalk with DPDT (or DPST) relays. You might need 10K - 100K "pull down" resistors on the inputs & outputs to keep anything from "floating up" and causing a click or pop when it's switched-in.

which will use a 12V trigger signal
DC, right? You wouldn't want those coils "transmitting" hum. And make sure to include a flyback diode on each relay coil.
 

egellings

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I have had excellent results using the Axicom model V23105-A5003-A201 DPDT fully enclosed small signal telecom relays meant for PCB mount. They can be had in the standard range of actuator coil voltages. I use DC actuation and use the obligatory back EMF suppression diode.
 
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starfly

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Line level signals aren't much of a problem. Resistance isn't an issue and I doubt you'll have crosstalk with DPDT (or DPST) relays. You might need 10K - 100K "pull down" resistors on the inputs & outputs to keep anything from "floating up" and causing a click or pop when it's switched-in.

DC, right? You wouldn't want those coils "transmitting" hum. And make sure to include a flyback diode on each relay coil.
Yes, DC. I know barely anything about electronics, but I figured out how to build a Purifi amp last year (well, it's more assemble than build) + adding a 12V trigger circuit to that build (using off the shelf relay boards I found on Amazon for cheap). That relay board does make a high pitched sound when I put my ear close to it, so that's why I'm looking for something a bit more suitable for transmitting audio signals.

I'll research the things you're suggesting.
 

Roland68

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I plan on building my own auto-switching input selector, which will use a 12V trigger signal to switch between my AVR or Streamer+DAC sources, which then get fed to my poweramp. The reason I'm doing this is that off the shelf solutions are either too expensive, or purely manual. And since I'm lazy, I don't want to have to get off the couch to switch inputs :)

What are good relays I can buy that have very minimal crosstalk? My research so far shows that can be a problem with some relays.
For example, I use this solution and it is absolutely inaudible:
Switch
Remote and relay volume control You have to scroll down to see the complete solution.
It works as an SE or Balanced. Relay based volume control is of course better than any potentiometer, but you don't have to use it. Unfortunately, it is necessary to operate the audio source switch board remotely and to have a display.

If you search for "Audio Source Switch Board" or "Audio Remote source switch" on aliexpress, you will find further solutions.
 
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starfly

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At this point I'm thinking of just creating a small PCB with a few terminal blocks (for easier wiring), and this relay:


In the default state, it would send audio from my DAC to my poweramp. When I switch on my AVR, the AVR would send a 12V signal to trigger the relay, at that point sending audio from the AVR instead of the DAC.

Looks like just this relay is all I'd need to pass on line level signals?

Edit: and well, I should perhaps add a flyback diode as suggested by @DVDdoug
 
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starfly

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I'm thinking of something like this:

1632953666523.png
 

0bs3rv3r

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What is the current drive capability of the 12V trigger? i.e. is it capable os handling the current drawn by the relay coil?

Also, to me, a trigger is more likely a pulse, not a continuous voltage. But I admit I do not know what is coming out of your AV amp.
 

MakeMineVinyl

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What is the current drive capability of the 12V trigger? i.e. is it capable os handling the current drawn by the relay coil?

Also, to me, a trigger is more likely a pulse, not a continuous voltage. But I admit I do not know what is coming out of your AV amp.
Triggers on AV equipment are not pulses but are constantly either on or off. For driving the coil, I would at least use an NPN transistor, or better still an opto isolator so that the upstream trigger doesn't have to source as much current, but of course you'd need a standby supply to do that. Just a cheap wall wart switching supply would do.
 

0bs3rv3r

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Triggers on AV equipment are not pulses but are constantly either on or off. For driving the coil, I would at least use an NPN transistor, or better still an opto isolator so that the upstream trigger doesn't have to source as much current, but of course you'd need a standby supply to do that. Just a cheap wall wart switching supply would do.

Good info on the trigger level. Thanks.

I agree on a driver transistor, unless there is some specification that says a "trigger" voltage must be able to deliver x amount of current at 12VDC.
 

MakeMineVinyl

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Good info on the trigger level. Thanks.

I agree on a driver transistor, unless there is some specification that says a "trigger" voltage must be able to deliver x amount of current at 12VDC.
There's no specification that I know of, but there could be something I'm not aware of. On our amplifiers and processors we use optocouplers in conjunction with a microcontroller to achieve this and other functions. This makes the trigger inputs a relatively high impedance.
 

charleski

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Good info on the trigger level. Thanks.

I agree on a driver transistor, unless there is some specification that says a "trigger" voltage must be able to deliver x amount of current at 12VDC.
There's no specification, but it seems generally safe to assume your 12V trigger will be able to source at least 100mA of current. Benchamark specs theirs for 200mA.
The datasheet for the relay that the OP linked shows it will draw 9.1mA. I think it's safe to hook this directly to the trigger (with a flyback diode) and not worry about rigging a supply just for the relay.
 

0bs3rv3r

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There's no specification, but it seems generally safe to assume your 12V trigger will be able to source at least 100mA of current. Benchamark specs theirs for 200mA.
The datasheet for the relay that the OP linked shows it will draw 9.1mA. I think it's safe to hook this directly to the trigger (with a flyback diode) and not worry about rigging a supply just for the relay.

Agree.
 
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starfly

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I'll measure the current output of my AVR's 12V signal later tonight to see if it would provide enough for this setup.
 
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starfly

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Alright, my Yamaha receiver outputs 12V DC at ~110mA, so it should be fine for this use case.
 
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starfly

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The best way to avoid crosstalk is to keep impedances low and use separate relays for the left and right channels. You should use inert gas filled gold contact relays for audio switching.
These are reed relays right? Any suggestions for gold contact relays? I don't seem to be able to find any on Mouser or Digikey.
 

Colin James Wonfor

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Have you tried the back to back opto coupled FETS, the low ESR type at 50V are very good. (some times called opto coupled SSR)
 
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starfly

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Have you tried the back to back opto coupled FETS, the low ESR type at 50V are very good. (some times called opto coupled SSR)
I haven't, but I'm also a complete novice when it comes to electronics circuit design (or anything electronics for that matter). I don't at all have an engineering background and am just getting started in the world of electronics (my amp build last year was my first time ever working with electronics so intimately).

So I'm open to any advice that would solve the problem I'm trying to solve. An easy to make circuit (will put it on a PCB so it's clean, and PCB manufacturing can be done pretty cheaply these days), with excellent characteristics for "audiophile" purposes :) I just want it to auto-switch from one source to another based on my AVR's trigger, and for the audio signal to be as perfect as possible, no added distortion, etc.
 
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