[sdiy] Relays or reed switches for routing?

[Mike Bryant]

> Why would relays introduce distortion ?

They don't, unless they are some pretty shit ones.  Panasonic ones are guaranteed for at least 100,000 operations and there is no contact non-linearity at all to cause distortion.  If you think about it they are just switches with an electromagnetic actuator and any music will have gone through dozens of switches and/or relays to get to your preferred method of audio delivery.  Or even hundreds if the recording studio has a computer controlled patch panel.  One more is not going to be audible.

Also on some older APs you can hear relays switching during measurements which far exceed the limits of human perception.  Not sure of their exact function but I bet it's to measure a reference signal first.

Finally, to not use them would break the first rule of pro-audio - "what would Rupert do ?" or unfortunately now "have done ?"

For example :
https://rupertneve.com/products/master-buss-converter

"These Reference Level calibration standards are implemented with a superb degree of accuracy via high-precision resistors and relay-controlled stepped attenuation."

Or for example look at the Amek 9098i he helped design, possibly the highest quality analogue mixer ever built where most signal switching is via relays.

So just use them - you'll be in the absolute best of company.



-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of cheater cheater via Synth-diy
Sent: 31 May 2021 13:58
To: Gordonjcp
Cc: synth-diy
Subject: Re: [sdiy] Relays or reed switches for routing?

Why would relays introduce distortion? Aren't they just a conductor that gets mechanically moved back and forth. What's the nonlinearity?

On Mon, May 31, 2021 at 2:10 PM Gordonjcp <gordonjcp at gjcp.net> wrote:
>
> On Sun, May 30, 2021 at 11:22:38AM +0200, cheater cheater wrote:
> > Why can I not use relays to switch audio? What's wrong with relays?
> >
> > BTW, I was thinking of acoustically dampening relays. EG use sound 
> > proofing foam.
>
> They're electrically noisy as well as mechanically noisy.  They're unreliable when you use them for switching tiny currents.  They introduce a lot of distortion.
>
> Literally nothing sane uses relays in the audio path.
>
> --
> Gordonjcp
>
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