Impedance switch: non-shorting that breaks signal to the OPT when switching?

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Deke609

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Hoping for some guidance.  I'm designing a simple output impedance switch for choosing between 3 secondary wirings on some new custom headphone OPTs for my Kaiju rebuild.

The switches will be topside - so I need to be careful. My intention is to only use the switches when no signal is playing -- but I have to allow for the possibility of an accidental switch when signal is playing.  I have no idea what harm, if any, a shorting switch might do to the OPTs, but I am pretty sure that my headphones or someone's ears might not like having two output impedances momentarily put in parallel - that could get loud. [Edit - on further thought, this will depend on whether the switch goes from high to low impedance, or vice versa -- so it's a draw whether I use shorting or non-shorting -- but I am still interested in opinions on my idea below in case it can protect the OPTs]

So my idea is to use a non-shorting switch (break before make) and use one pole just to break signal going to the OPT.  I.e., as all other connections are broken then re-made, so is the input signal connection to the OPT. I'm hoping this would protect (or at least minimize harm to) the OPT/headphones/ears.

Does that make sense? Any thoughts or suggestions?

many thanks, Derek
« Last Edit: July 26, 2020, 12:21:56 PM by Deke609 »



Offline Paul Birkeland

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I would not break the connection to the OPT, you should be fine using either shorting or non-shorting switches here, especially if the secondary of the transformer you're using just has 0-4-8-16 connections. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Deke609

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Thanks PB. It's 3K3:16/32/64 in case that makes a difference.

cheers and thanks, Derek