Idea for switching on an external amp with receiver. What do you guys think? [Archive] - Audio & Video Forums


View Full Version : Idea for switching on an external amp with receiver. What do you guys think?

03-17-2009, 01:56 PM
Ok guys. My original problem was that I needed a way to turn my amps on when the receiver turns on. I developed this idea in another thread while I was trying to figure out if I could use the "control out" jacks on my receiver.

Here is where the thread left off. I was going to just use the "control out" jacks and a relay to switch on the amps......

Well I ran into a little problem already... go figure.

For some stupid reason I assumed the amp switch would be 12v. WRONG. DUHHHH.

PROBLEM 1: The amp switch is 120V. Ok, not that big of a deal.
SOLUTION: 120V relay that uses a 12V coil (trigger). Found one for $10.

PROBLEM 2: The relay's coil side (switched/trigger side) uses 30mV. The control jacks on my receiver are only rated up to 15mV max! UGH!
SOLUTION: Use the "switched outlets" on the receiver as a "trigger" for the relay. Luckily for me, the relays that I had ordered can also be controlled using 120V on the coil side. (Let me add that my receiver's two switched outlets are only rated for .8A total. My two amps combined are 9.2A total. This is why I can't just plug them into the receiver... obviously)

FINAL SOLUTION: Build an external relay control unit (I will call it RCU for short) using the relay and some power cords and a standard outlet. Both amps will plug into the RCU. I will have one power cord coming from the RCU and plug into the switched plug at the back of the receiver. This is what will switch the relay on. Another power cord will come from the RCU and plug into an outlet. This will power both amps through the relay. Each of my M-501's are rated at 4.6A. The relay is rated to 10A. I know it's cutting it close, but it should be fine.

What does everyone think?

03-17-2009, 03:44 PM
What does everyone think?
Alternative solutions:

1. Buy amps with 12v trigger capability.
2. Train your wife how to use the remotes.

Option # 2 worked fine for me. :)


03-17-2009, 03:50 PM
Yes, your solution would work, but what fun is that? I like being able to say, "yeah, I made that."

Not to mention, I bought 2 Onkyo M-501 amps for a total cost of $145, including fuel to pick one up 2 states away. They got pretty good reviews, and they retail for $400 a piece. I think I'll keep em for now.