TOPIC:

With corona I have a bunch of spare time on my hands I was looking to see if I can solve my "issue" of not being able to trigger my monoblocks on/off. My amps are connected to my SHD via XLR, which leave RCA 1 and 2 available. Would it be possible to connect RCA1/2 to an Arduino which listens for imput and then, after recieving sends a 12V signal to my amp? (arduino being powered separately). My amps only have on/off switches on the rear so turning them on and off every time is a bit of a hassle so now they're just always on, though the power draw is very low.

This project has "ground loop" written all over it but it seems like a fun experiment.

That seems feasible. Ground loops are obviously a potential problem as you say but you could probably solve that either with an audio isolation transformer on the audio signal to the arduino and/or an opto-isolator on the digital signal to your amps. Then again perhaps a low voltage relay would be better, the contacts could switch the 12V which the arduino might not otherwise be able to generate and the coil is galvanomically isolated from the contacts. I've never used an arduino but most microcontrollers seem happier with 3.3V or 5V.

So the hardware doesn't seem to need any complicated or expensive parts, then it's just a matter of writing the firmware

I've also never worked with Arduino before but this seems like a nice and feasible project. Indeed a relay might be a better idea than from the Arduino directly. I'm going to dive into this and post updates here if I actually get around to doing this!

how about this?
www.bobwireaudio.com/

This is exactly what I would be building! Could you trigger two separate amps with one device you think? As having to drop 200 for such a small project seems a bit extreme to me

It has two 12V trigger outputs but they function differently. Even a single 12V trigger out can be connected to many different destinations though, as shown in the manual, so as long as you can sort the cable splitting out it should work fine..

just use a mono Y-cable

just use a mono Y-cable to split to two amps

This BobWire thing is new to me but seems like a great option. One thing: it apparently only works off a toslink signal. That’s not your use case, and the SHD doesn’t have toslink out. Looks to me like you’ll have to use either a cheap RCA-to-toslink ADC if you want to use RCA out, or you could use the SHD’s spdif digital out and a cheap spdif-to-toslink converter. Either of those would be about $15 on Amazon. Obviously you just let the digital signal die inside the BobWire and use it for the 12v trigger.

Just curious, has anyone actually done this? If this works, it would be an awesome workaround to power the amp with a Minidsp SHD.

I can’t say definitively, but I think it won’t work as expected. I tested the SHD’s coaxial out with a coaxial input DAC that has a light to indicate a locked signal. When the SHD is completely off with the rear switch, it shows no signal as you’d expected. When the SHD is fully on, then it shows a lock, again, as you’d expect. But when I put the SHD in standby via the remote, the locked coaxial signal remains. So I don’t see how the BobWire device won’t constantly see a signal from the SHD indicating that it should keep the amp triggered on.

SHD “standby” seems to be to be more of a “internals on but display off and output muted” rather than an actual standby mode. I get kind of a low-amplitude, high-pitched noise from tweeters when I mute the SHD during normal operation, and I get the exact same noise in standby mode.

I’ll send an email to minidsp about this, but at the glacial pace that other items are being addressed I don’t think they’ll get around to this anytime this millennium. Would be great to have a little checkbox somewhere in the plugin to decide whether you want outputs to remain on while in standby.