Switch Differences

fastlanestoner · 2nd February 2012

I've been learning how to construct my own pedals, and I was just wanted to find out from the experts about the different kinds of switches.

3PDT - true bypass capable. normal on/off. more connections = more options, but what for?

DPDT - normal on/off. what else?

SPDT -

SPST - momentary only?

Anything double-throw would work for an effect in terms of on/off? Single throw would work if I kept the switch engaged?

It's hard to get the 3PDT and I was wondering if using another option would poison the sound. I'm always learning. THanks!

Peterson Goodwyn · 2nd February 2012

A switch is a switch is a switch. Choosing at different configuration won't poison your sound if it's set up correctly.

Any switch may be used for a number of different purposes. Also the simple four letter/number designation doesn't tell you whether the switch is temporary or not.

A couple of usage examples:
DPDT - Flipping polarity of a balanced signal, or L/R for stereo
SPDT - Switching between two signal paths for a mono/unbalanced signal
SPST - Standard on/off

Matt Syson · 2nd February 2012

Hi
You design your circuit, then find a switch to fit the requirements.
As not all permutations are necessarily available it may be an iterative process and you may need to redesign the circuit if you can't get the contact arrangement you want.
Matt S

fastlanestoner · 2nd February 2012

Cool thanks guys! I just found some great resources on the net too. Thanks!

trumq · 2nd February 2012

With regard to pedal construction, DPDT gives you true bypass, TPDT is generally used to add an LED status indicator. SPDT can "poison the sound" when used as a bypass switch, because you have to leave the effect input connected even when you are monitoring the bypassed signal. If the input of the effect has a high enough impedance, the tone sucking may not be noticeable.

A SPST momentary footswitch can be used to trigger a digital logic circuit switch to toggle between 'engaged' and 'bypassed.'

2nd February 2012	#1
fastlanestoner Lives for gear Joined: Oct 2010 Location: Long Beach, CA Posts: 1,746 Thread Starter	Switch Differences I've been learning how to construct my own pedals, and I was just wanted to find out from the experts about the different kinds of switches. 3PDT - true bypass capable. normal on/off. more connections = more options, but what for? DPDT - normal on/off. what else? SPDT - SPST - momentary only? Anything double-throw would work for an effect in terms of on/off? Single throw would work if I kept the switch engaged? It's hard to get the 3PDT and I was wondering if using another option would poison the sound. I'm always learning. THanks! __________________ Guitar/Backline Tech and Mobile Recording services in the Los Angeles area! New AEP site is up! Custom gear and cabling! Custom DAWs! Die-hard Phila Eagles fan!

2nd February 2012	#2
Peterson Goodwyn Gear Head Joined: Sep 2010 Location: Seoul Posts: 60	A switch is a switch is a switch. Choosing at different configuration won't poison your sound if it's set up correctly. Any switch may be used for a number of different purposes. Also the simple four letter/number designation doesn't tell you whether the switch is temporary or not. A couple of usage examples: DPDT - Flipping polarity of a balanced signal, or L/R for stereo SPDT - Switching between two signal paths for a mono/unbalanced signal SPST - Standard on/off __________________ DIY Recording Equipment Database Resume as an engineer/producer.

2nd February 2012	#3
Matt Syson Lives for gear Joined: Sep 2004 Location: UK Posts: 4,822	Hi You design your circuit, then find a switch to fit the requirements. As not all permutations are necessarily available it may be an iterative process and you may need to redesign the circuit if you can't get the contact arrangement you want. Matt S __________________ Matt S www.mseaudio.co.uk

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2nd February 2012	#5
trumq Gear Head Joined: Sep 2011 Posts: 55	With regard to pedal construction, DPDT gives you true bypass, TPDT is generally used to add an LED status indicator. SPDT can "poison the sound" when used as a bypass switch, because you have to leave the effect input connected even when you are monitoring the bypassed signal. If the input of the effect has a high enough impedance, the tone sucking may not be noticeable. A SPST momentary footswitch can be used to trigger a digital logic circuit switch to toggle between 'engaged' and 'bypassed.'