Hmm, to be honest, I'm actually posting this in reverse. My sourcing of pre-outs project should've been first, because if it wasn't for getting that right, I wouldn't have done this little project. The pre-out project was a proof of concept that actually worked very well. I'll post it once I've got all the parts and a PCB made to do it properly.
Anyway, I've got an Onkyo TX-NR575E, it's an entry level 4K HDR Atmos AVR with no pre-outs or 12V trigger. Certainly wasn't intended to be used with any power amps what-so-ever. It's got a USB port, pre-out for the sub and bizarrely, a stereo pre-out for "Zone 2". If you are going to do any pre-outs, at the very least, have them for the fronts, not Zone 2, I mean really, what's the point???
When I was setting the amp up, one of the options in the menu was to enable or disable power to the USB port when the amp was in standby. It got me thinking, there must be a way to use the USB port as a 12V trigger to control the power amp. I thought of various ways to up the 5V to 12V using a buck converter or other such means, but it seemed overly complicated. I scratched through my box of bits and found a 5V relay that I had used on a project for my Commodore Amiga aeons ago.
The relay would be perfect for the job, so I changed thought direction completely and decided to rather use the relay to just switch a normal multiplug on and off. After opening my one multiplug I realised that there?s very little space in there and certainly not enough for the relay. I scratched around some more and found an old wall socket that had a dual socket on it as well as an old 2-way USB extension bracket. I went off to Builders and bought a plastic box for the wall socket and a couple of extra bits and bobs.
This is what I ended up with:
I took apart the USB extension bracket, the metal bracket made the perfect template and I could re-use the screws that held it all together.
Marked where the holes needed to be cut out:
Drilled and cut out the holes. Used a needle file to clean it up a bit. It?s not perfect, but good enough for the job.
Screwed in the USB sockets and cable using the original screws
Wired up the relay to the USB cable and power cable and stuck the relay down with some double sided tape. Did a quick test with the USB cable, plugging it in and out of my PC. The relay made and broke contact as it should.
Final assembly
Overall, it works really well for such a hack job. In a way, it works better than a proper 12V trigger as my Rotel RB-985 doesn?t have a 12V trigger input. They only appeared on the later models. The Citation 7.1 does have a 12V trigger, but still uses some power in standby mode. By using this, both amps are switched off completely and use zero power.
Now the amps sit happily in their place, no longer disturbed when switching on and off.
Anyway, I've got an Onkyo TX-NR575E, it's an entry level 4K HDR Atmos AVR with no pre-outs or 12V trigger. Certainly wasn't intended to be used with any power amps what-so-ever. It's got a USB port, pre-out for the sub and bizarrely, a stereo pre-out for "Zone 2". If you are going to do any pre-outs, at the very least, have them for the fronts, not Zone 2, I mean really, what's the point???
When I was setting the amp up, one of the options in the menu was to enable or disable power to the USB port when the amp was in standby. It got me thinking, there must be a way to use the USB port as a 12V trigger to control the power amp. I thought of various ways to up the 5V to 12V using a buck converter or other such means, but it seemed overly complicated. I scratched through my box of bits and found a 5V relay that I had used on a project for my Commodore Amiga aeons ago.
The relay would be perfect for the job, so I changed thought direction completely and decided to rather use the relay to just switch a normal multiplug on and off. After opening my one multiplug I realised that there?s very little space in there and certainly not enough for the relay. I scratched around some more and found an old wall socket that had a dual socket on it as well as an old 2-way USB extension bracket. I went off to Builders and bought a plastic box for the wall socket and a couple of extra bits and bobs.
This is what I ended up with:
I took apart the USB extension bracket, the metal bracket made the perfect template and I could re-use the screws that held it all together.
Marked where the holes needed to be cut out:
Drilled and cut out the holes. Used a needle file to clean it up a bit. It?s not perfect, but good enough for the job.
Screwed in the USB sockets and cable using the original screws
Wired up the relay to the USB cable and power cable and stuck the relay down with some double sided tape. Did a quick test with the USB cable, plugging it in and out of my PC. The relay made and broke contact as it should.
Final assembly
Overall, it works really well for such a hack job. In a way, it works better than a proper 12V trigger as my Rotel RB-985 doesn?t have a 12V trigger input. They only appeared on the later models. The Citation 7.1 does have a 12V trigger, but still uses some power in standby mode. By using this, both amps are switched off completely and use zero power.
Now the amps sit happily in their place, no longer disturbed when switching on and off.
