Triggering pro audio sub amp on/off for HT

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m R g S r

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Joined 2011
#1
How would you trigger a pro amp on/off with your receiver that doesn't have a 12v trigger? I thought the receiver had one, and was going to use a 12v solid state relay, but turns out it doesn't.

I want my sub amp to come on off with just remotely turning on the receiver.

I have:
Marantz sr5006
Qsc mx1500 quiet fan mod for HT use
Mini DSP

The mini DSP is powered off the USB of the receiver, so that comes on / off with the receiver.

I pulled the power switch from the QSC and ran wires to the back for the switch, so I can mount a relay in the future if that will work. It's 120VAC switch

I'm thinking a 5V solid state relay which grabs power from the mini DSP, which would be powered up when the receiver turns on. I'm just not sure if there is enough power from the USB to operate a relay, and if I can find a relay that will have a high enough amperage rating for the QSC amp. (As far as I can tell, the power comes in through the main power switch first on the QSC, so it needs to be able to handle 15amps or so)
Any suggestions for good solid state relays?

I Also don't know if the external power connection and the mini USB in on the mini DSP are connected in parallel without a diode?


Any other CHEAP solutions for simply getting the amp to power on when I turn the receiver on?
 
#8
That would have made all this easier. There's no 12v trigger of any kind on it.
I originally thought there was and was about to order the relay i had picked out (12v, zero cross, 120V 20amp) but I decided to double check And there is no trigger. Grrr
 
#9
Lol, yeah I know how it works. For the last 25 years they always has such trigger.... and now after 25 years you need it for the first time and now there ain't...
I guess you are still under the warranty period, I guess, so getting internal 12V is not really an options either. Well, the photo/light sensitive switch + USB-led is still an option.
 
#12
m R g S r said:
I'm thinking a 5V solid state relay which grabs power from the mini DSP, which would be powered up when the receiver turns on. I'm just not sure if there is enough power from the USB to operate a relay, and if I can find a relay that will have a high enough amperage rating for the QSC amp. (As far as I can tell, the power comes in through the main power switch first on the QSC, so it needs to be able to handle 15amps or so)
Click to expand...

If you are looking for an USB driven relay, you may want to have a look here:

Yocto-PowerRelay - Tiny USB relay (SPDT) for switching mains powered appliances

These can have customized firmware making them switch as soon as they are powered. Unfortunately, they can handle 5A only. But you can use them to drive a much bigger relay.
 
#13
Hi m R g S r,

Post #1: "...I pulled the power switch from the QSC and ran wires to the back for the switch, so I can mount a relay in the future if that will work. It's 120VAC switch."

That's where you could tap in for driving the 120VAC coil of the power contactor. (Using a contactor will give you a great deal of freedom as to the amount of power you are switching.)

Or, you could drive the power contactor coil of a 5VDC relay connected to the 5 V line from the USB plug (as Djim and Yoctopuce pointed out), with the relay switching the 120VAC for the contactor coil, e.g.: Relay 5V DC SPDT Power 2A 250VAC 10pcs | eBay

You might want to put a reverse connected diode accross the 5V relay coil to reduce coil related spikes on the USB 5V line.

Or use something as Cokewithlime suggested, that should work just fine.

Regards,
 
Last edited:
#15
tb46 said:
Hi m R g S r,

Post #1: "...I pulled the power switch from the QSC and ran wires to the back for the switch, so I can mount a relay in the future if that will work. It's 120VAC switch."

That's where you could tap in for driving the 120VAC coil of the power contactor. (Using a contactor will give you a great deal of freedom as to the amount of power you are switching.)

Or, you could drive the power contactor coil of a 5VDC relay connected to the 5 V line from the USB plug (as Djim and Yoctopuce pointed out), with the relay switching the 120VAC for the contactor coil, e.g.: Relay 5V DC SPDT Power 2A 250VAC 10pcs | eBay

You might want to put a reverse connected diode accross the 5V relay coil to reduce coil related spikes on the USB 5V line.

Or use something as Cokewithlime suggested, that should work just fine.

Regards,
Click to expand...

The coil on the contactor would only be provided power via USB from the receiver turning on and off. And that wouldn't be sufficient.

The switch on the second amp, the qsc, the one I want to Come on and off with the receiver, is 120vac.

For now I picked up a master/slave power strip. That will suffice for the time being until I upgrade to a dedicated theater with dedicated power, and some large horns / multiple sub Amps.

Thanks for he help guys, ill use this in the future!
 
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