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Author Topic: Relays in audiopath?  (Read 4395 times)

Ted Olausson

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Relays in audiopath?
« on: October 05, 2006, 09:24:54 pm »

I have been asked to build a voicepedal for a singing guitarplayer.
Its meant to switch between reverb, distorted voice and clean voice for stageuse.He has a preamp.

I was thinking about making a passive box with relays to make the switching between different signalpaths.
But is relays really such a good idea? will they make noises (poff, bang) when they are switching? or are there any ways around that?

I dont have any experience with FETs so i dont have the time/courage to walk that path unless someone has a bombproof schematic to share.
So what alternatives are there to relays? any good ICs maybe?

PS: I have included a pic of the schematic just in case anyone is curious of what it is...
Audio in is from his preamp, cleanout goes directly to the mixer, fx1out and fx2out is sends to his effects.(It is balanced lines even if only one path is drawn)

index.php/fa/3569/0/
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Brian Roth

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Re: Relays in audiopath?
« Reply #1 on: October 07, 2006, 03:45:26 am »

Use sealed relays, preferably with bifurcated, gold-plated contacts.

Wire a diode in parallel with each relay coil (the cathode end goes to the most positive end of the coil) to reduce/eliminate "pops" created when the relay is de-powered.

Rethink your audio path so that any unused "destination" is shorted by the relay contact versus leaving that destination open circuited.

Bri

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Brian Roth Technical Services
Oklahoma City, OK
www.BrianRoth.com

dementedchord

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Re: Relays in audiopath?
« Reply #2 on: October 07, 2006, 05:32:35 pm »

just a thought... anyone ever try using 4066 biquad switches for this kinda thing??
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Ted Olausson

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Re: Relays in audiopath?
« Reply #3 on: October 08, 2006, 08:41:00 am »

dementedchord wrote on Sat, 07 October 2006 16:32

just a thought... anyone ever try using 4066 biquad switches for this kinda thing??


Thats an idea i also was wondering about...

-Anyone have any experience with any of those analog cmos swithces in audio? (4051 is quite popular for D/A converters)
Any SQ difference between manufacturers?

-Are there any cheaper alternatives to SSM2402/SSM2412 audio switches?


The soundquality is not the main concern, however it should be okay. its not for studiouse only for practising and pubgigs.
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Brian Roth

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Re: Relays in audiopath?
« Reply #4 on: October 09, 2006, 04:53:11 am »

A 4066, et al all have a relatively high series resistance...as in dozens or hundreds of Ohms versus a tiny fraction of an Ohm as found with a decent relay.

TANSTAAFL.

Bri

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Brian Roth Technical Services
Oklahoma City, OK
www.BrianRoth.com

Ted Olausson

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Re: Relays in audiopath?
« Reply #5 on: October 09, 2006, 05:18:10 am »

I got some good replys over at the srforums on how to solve the problems inherent in 4066.
However, the construction got a little bit to complicated for this cheap project.

http://srforums.prosoundweb.com/index.php/t/17465/15898/
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