[sdiy] Relays or reed switches for routing?

[Mike Beauchamp]

I recently tested some analog audio switch IC's and was very happy with 
the results. Some are in packages of 4 switches in a single IC, and are 
configured as SPST switches either normally open or normally closed or 
even SPDT switches. Each "switcH" has a logic input and you hit it with 
5V logic signal and the switch does its thing.

I've repaired a few guitar amps where relays were the culprits of some 
intermittent behavior or not working. They also require a relatively 
high current 12V supply to activate the coils in the relays.

Mike

On 5/30/21 4:27 AM, cheater cheater via Synth-diy wrote:
> Hi all,
> this is only tangentially synth related, but I believe some of this
> applies pretty well to synths as well.
> 
> I would like to build a monitor controller for my speakers. They're a
> monitoring set which I'm building up for a future mastering studio.
> 
> 
> Here's my current setup:
> 
> DAC -> preamp -> active line level analog crossover -> 3x power amps -> speakers
> 
> I would like to accomplish a few things.
> 
> First of all, because the power amps have very high amplification, I
> need to insert attenuating pads in front of them. They need to be
> after the xo (crossover) but before the power amps; it's because if
> the attenuation happens before the crossover, then the crossover's
> self noise starts being noticeable. (however, using 48Vpp op amps, it
> has a huge dynamic range). So I need to attenuate 6 balanced signals
> (later 8, once I change the electronics to 4-way amplification). As a
> certain level of attenuation might be good for long term listening,
> and meanwhile you might want to listen at higher volumes every now and
> then for checking what a song sounds like at high SPL. So I'd like to
> build a switchable pad. This is for voltages that are up to 50V. I'm
> not sure what to use here: relays, reed switches, or something else? I
> don't want to use any semiconductor based system as this is for
> mastering, so a) fluctuations in resistance will mean differences in
> levels and b) additional distortion is not good.
> 
> I'd be looking for something that's able to be switched quickly and
> efficiently, but is also quiet, and won't need replacing very quickly.
> Having loud "thock" happen during monitoring would be disruptive to
> work, as you really want to listen to the music itself.
> 
> Second of all, I'd be looking to build an output switching system for
> hooking up the speakers either to the 3-way amplification system, or
> to just one of the amplifiers, as a 1-way amplified speaker. This is
> to simulate different ways of listening to the music. I understand at
> this point, this will require handling of high currents. The largest
> of these power amps is able to produce up to 900W. I would most likely
> be automatically turning off these amplifiers before re-routing the
> outputs, but I understand that any relays or reed switches still need
> to be able to handle the current going through them during operation.
> 
> 
> I would appreciate any suggestions. What do I use: relays? reed
> switches? some sort of mechanized throw switches?
> 
> Thanks
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