[sdiy] Relays or reed switches for routing?

cheater cheater cheater00social at gmail.com
Mon May 31 22:53:53 CEST 2021

Hi Tom,
thanks a lot.

I don't care much about electrically silent switching - just
mechanically silent would be nice.

I can't use semiconductor attenuation elements because the monitoring
setup for mastering has to be repeatable and we're operating at pretty
low tolerances here with regards to matching the stereo as well as
matching the separate parts of the balanced attenuation. Matching
groups 16 attenuating resistors (balanced * 8 bands) will be bad
enough... I don't think I would want to do that with semiconductors...


On Mon, May 31, 2021 at 10:48 PM Tom Wiltshire <tom at electricdruid.net> wrote:
> It’s not that they cause distortion. If there is a problem with relays, it would be contact bounce. The acoustic noise they make is not the issue so much as the electrical noise. They switch fast, so any non-zero signal causes a click. Obviously some are much worse than others. Some may be good enough. Silent switching generally means “slow switching” - it’s a crossfade in a few tens of msecs, not a hard jump from one to another.
> In stompbox-world, a lot of people are currently hung up on “true bypass switching” which is (mostly) taken to mean a solid path of metal from input to output when the effect is out of circuit. This is the current holy grail because having extra buffers in your signal path is taken to be clearly wrong (despite highly-thought-of mixing desks having dozens between the signal coming in and going out). In an attempt to meet this demand whilst providing silent switching (and also to avoid expensive and failure-prone 3PDT footswitches), some manufacturers have moved to relays, but these are often (mostly) accompanied by some type of short-to-ground element to silence the output while the relay switches. This makes up for the instantaneous switching and contact bounce of the metal-on-metal relay switching. The previous pedal generation used FETs to provide this switching action, and they could be ramped on softly, unlike relays. But for pedalworld, switching FETs in the signal path and the buffers that go with them are now often regarded as not the right answer, so other solutions have been found that hit the current marketing buzzword.
> HTH,
> Tom
> ==================
>        Electric Druid
> Synth & Stompbox DIY
> ==================
> > On 31 May 2021, at 13:57, cheater cheater via Synth-diy <synth-diy at synth-diy.org> wrote:
> >
> > 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
> >>
> >> _______________________________________________
> >> Synth-diy mailing list
> >> Synth-diy at synth-diy.org
> >> http://synth-diy.org/mailman/listinfo/synth-diy
> >> Selling or trading? Use marketplace at synth-diy.org
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> > Selling or trading? Use marketplace at synth-diy.org

More information about the Synth-diy mailing list