Passive summer using relays?

[Grooveteer]

So... I still haven't finished my 12 channel summing box..  :

I want to be able to route all channels to L/C/R a la the Sumthing.

Is there a reason that no one seems to be using relays instead of just switches?  (besides the fact that using DPDT switches is easier and you don't need a PSU)    I have plenty of cheap toggle switches around and 24 omron G5V-2 relays at 2 EUR a piece would be cheaper than 24 good quality toggle switches. (I'm always a bit worried about runinig audio through a toggle)

It would also allow me to have LEDs showing the routing...

a 5V wallwart is not a problem either.

Do you guys see any issues with replacing the DPDT switches with relays in the Sumthing schematic?

Thanks!

Grooveteer

 

[Svart]

Other than the obvious cost differences there would be no sonic difference(unless your relay voltages are noisy and they you might get some coupling to the contacts from the relay coils).  The majority of relay users seem to think that a hermetically sealed relay's contacts won't corrode and cause impedance/resistance/etc fluctuations.  While this is technically true, I don't think it's that much of a problem since most quality switches have enough contact force to scrape any corrosion clean.  Corrosion is not likely anyway as most quality switches have contact lube applied when they are assembled anyway.

I think you already stated why the Sumthing doesn't use relays.  It doesn't need power, decoupling, extra wiring, etc.  Once you add all of that AND include the relay switching controls, you would have spent more than just the difference between the switches and relays.

It's your box to design how you want though.  If adding the complexity and cost will make you happy or you are simply trying to learn how to do it, then by all means go for it! 

 

[Grooveteer]

Thanks for the info!    It just seems like a fun project to tackle, but I'm probably making things more complicated than needed. (my wife could tell you stories...)

One more question: Does it matter is the 10K resistors are before or after the switch, I don't think so as they're in series.  I was thinking of placing them right after the inputs, but I see the sumthing has them after the mult and 2PDT, meaning you need twice as many resistors. That puzzles me..

So much to learn  ;D

Cheers!
G

 

[Svart]

Which switch?  They need to be after the bypass switch or else it's not true bypass.  They also need to be after assign switch because no matter which bus the input is routed to you still need the same amount of bus impedance regardless of assigned tracks.

 

[Grooveteer]

I meant the assign switch.  So it's about the bus impedance... That makes sense.

Thanks for explaining Svart. Much appreciated.

Cheers,
Grooveteer (learning every day)