24V Trigger? - AVS Forum
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post #1 of 16 Old 07-18-2013, 05:13 PM - Thread Starter
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I have an amp that I want to trigger when my setup turns on. It requires a 24v trigger. Currently, I have a 24V wall wart connected on my receiver's switched outlet that triggers it. However, i'm upgrading to a preamp that doesn't have a switched outlet, but has 3 12v triggers.

What is the easiest way to get this to happen? If i combine 12V triggers it won't = 24v, correct? I was thinking a relay, but it's kind of a hassle to wire everything up. Any other ideas?
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post #2 of 16 Old 07-18-2013, 05:35 PM - Thread Starter
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is something like this the easiest way to go?
http://www.amazon.com/3-5-30V-4-0-30V-Booster-Converter-Regulator/dp/B008FLE7PA/ref=sr_1_24?s=automotive&ie=UTF8&qid=1374194011&sr=1-24&keywords=voltage+step+up
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post #3 of 16 Old 07-18-2013, 07:45 PM
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Or this: http://www.amazon.com/LM2577-Adjustable-Step-up-Converter-Module/dp/B008HMETBE/ref=pd_bxgy_e_img_z
Looks like either would do the trick.


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post #4 of 16 Old 07-18-2013, 08:58 PM
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Quote:
Originally Posted by JoeMG View Post

It requires a 24v trigger.
Requires, or supports? Most amps that support a 24v trigger will work just fine with 12V.
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post #5 of 16 Old 07-19-2013, 04:58 PM
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You can also ,if you want, use 2- 12 volt wall warts in series to get the 24 volts if necessary but keep mind the DC output rating of the WW is calculated with a load. There is essentially no load provided by a trigger circuit so the output of a WW rated at 12 volts is likely more like 18 which will definitely trigger a 24v input
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post #6 of 16 Old 08-31-2013, 03:41 PM - Thread Starter
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I ended up using this: http://www.amazon.com/gp/product/B0085T97PW/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1

It worked fine at first... but now the DC trigger doesn't seem to work. if i plug it into the other DC trigger it works. I'm wondering if i blew a fuse or damaged the 12v trigger? it's a marrantz av8801... is there a fuse or something for the trigger?

I don't see how this could have damaged the unit... but i'm afraid to use the other trigger incase it damages it.

basically, i need to find a way to provide 24v, 125ma to this amp when the preamp goes on.
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post #7 of 16 Old 08-31-2013, 04:58 PM - Thread Starter
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I think I found a reasonable solution.

I got an AMX PC-1 off ebay... i'll just use a 24v wall wart with that. should do the trick and not risk my other trigger.
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post #8 of 16 Old 08-31-2013, 05:31 PM
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Quote:
Originally Posted by JoeMG View Post

I'm wondering if i blew a fuse or damaged the 12v trigger?
Sounds likes it.
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I don't see how this could have damaged the unit...
Then you don''t know enough to be playing EE. If you have to provide 24V at 125ma from a 12V source, ignoring losses in the covereter that source is going to have to provide at least 250ma. The AV8801 trigger is rated 125ma. There is no such thing as free power. And the inrush current of the converter you used could be much more than that.
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...i need to find a way to provide 24v, 125ma to this amp when the preamp goes on.
And just what make and model amp would that be?
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post #9 of 16 Old 08-31-2013, 05:34 PM
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Quote:
Originally Posted by JoeMG View Post

I think I found a reasonable solution..
I don't think so. That device expects to see a contact clousure, not a voltage. Can the AV8801 work that way?

You are getting closer to a solution, though. All that is required is a 12V relay and a 24v wall wart. But you knew that to start with.
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post #10 of 16 Old 08-31-2013, 05:51 PM - Thread Starter
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Quote:
Originally Posted by Colm View Post

Sounds likes it.
Then you don''t know enough to be playing EE. If you have to provide 24V at 125ma from a 12V source, ignoring losses in the covereter that source is going to have to provide at least 250ma. The AV8801 trigger is rated 125ma. There is no such thing as free power. And the inrush current of the converter you used could be much more than that.
And just what make and model amp would that be?

well, I definitely agree I don't know enough about this, which is why i started this thread.

help me understand... the pre/pro outputs 12v 150ma, even if the current was less than the 125ma expected by the amp, how would that damage the trigger output? I'm not familiar with the term "inrush current". In my experience with this amp, when there's not enough current, it won't turn on, which wasn't the case here.

It's a Crestron cnampx-7x200... the way i've been using it is that I "fake" a cresnet connection (24v, 125ma) with a 24v ac adapter... this worked great for a while, but i recently upgraded to a pre/pro without a switched AC outlet like my receiver had.

when you say it expects a contact closure... again, i'm really unfamiliar with this, how does that differ from a trigger?

Any help you can lend is greatly appreciated.
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post #11 of 16 Old 08-31-2013, 06:03 PM - Thread Starter
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Here are 2 threads that led me to believe the AMX unit is what I needed... please let me know if i'm wrong (which is totally possible):

http://www.htguide.com/forum/showthread.php?32402-12-volt-trigger-outlet
http://www.avsforum.com/t/1454978/are-there-any-simple-switched-power-outlets-that-work-with-a-12v-trigger-for-sub-woofer
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post #12 of 16 Old 08-31-2013, 06:08 PM - Thread Starter
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by contact closure... Do you mean a constant output vs a pulse? I believe the Marantz gives a constant output... I had the amp on for hours yesterday with the 24v step-up from the trigger, if it was a pulse it never would have stayed on.
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post #13 of 16 Old 08-31-2013, 09:59 PM
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Quote:
Originally Posted by JoeMG View Post

... the pre/pro outputs 12v 150ma, even if the current was less than the 125ma expected by the amp, how would that damage the trigger output?
The AV8801 is capable of safely providing 12V at up to 125(150?) ma. How much current it will actually provide is a function of the resistance in the device it is connected to. The resistance at the amp is sufficient to limit it to a safe value when connected directly. It doesn't turn on because the voltage is insufficient. The amp requires 3W of power (24V x 125ma). When you put the power converter in the between the two devices, it has to draw 3W plus from the AV8801. 3W = 12V x 250ma. IOW it has to draw twice as much current from the AV8801 than it is designed for.
Quote:
I'm not familiar with the term "inrush current".
The power converter is a switch mode power supply. There can be a capacitor in the input to it that looks like a dead short to the AV8801 until it charges up.
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when you say it expects a contact closure... again, i'm really unfamiliar with this, how does that differ from a trigger?
A contact closure is like a mechanical switch. If you were to connect a light switch across the terminals of the AMX PC-1 and your amp was plugged into it, flipping the switch would turn the amp on and off. This is quite different from supplying 12V across those two terminals. Depending on the design of the PC-1 and how you hook it up, you might get lucky and have it work. or it may not work, or it may destroy another trigger output, or you may destroy the PC-1.

FWIW a Niles AC-3 or a Xantech AC1 will do what you are trying to do with the AMX PC-1.
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post #14 of 16 Old 09-01-2013, 05:12 AM - Thread Starter
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Quote:
Originally Posted by Colm View Post

The AV8801 is capable of safely providing 12V at up to 125(150?) ma. How much current it will actually provide is a function of the resistance in the device it is connected to. The resistance at the amp is sufficient to limit it to a safe value when connected directly. It doesn't turn on because the voltage is insufficient. The amp requires 3W of power (24V x 125ma). When you put the power converter in the between the two devices, it has to draw 3W plus from the AV8801. 3W = 12V x 250ma. IOW it has to draw twice as much current from the AV8801 than it is designed for.
The power converter is a switch mode power supply. There can be a capacitor in the input to it that looks like a dead short to the AV8801 until it charges up.
A contact closure is like a mechanical switch. If you were to connect a light switch across the terminals of the AMX PC-1 and your amp was plugged into it, flipping the switch would turn the amp on and off. This is quite different from supplying 12V across those two terminals. Depending on the design of the PC-1 and how you hook it up, you might get lucky and have it work. or it may not work, or it may destroy another trigger output, or you may destroy the PC-1.

FWIW a Niles AC-3 or a Xantech AC1 will do what you are trying to do with the AMX PC-1.

Thank you for the explanation... Looks like I have a lot to learn about electricity.
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post #15 of 16 Old 09-01-2013, 08:11 AM - Thread Starter
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I had an epiphany last night... I wish I had thought of it from the get-go... I have a Belkin PF60 power conditioner with a 12v trigger... so i wired the marantz to the power conditioner and set 1 bank of outlets to be switched, plugged the 24v ac adapter into the switched bank and now it works perfectly.

Hopefully someone else can learn from my mistake.


As far as the trigger on the marantz goes... does anyone have any idea if there is a fuse i can replace or did i just ****up my brand new preamp?
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post #16 of 16 Old 09-01-2013, 11:50 AM
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Cool!
Quote:
Originally Posted by JoeMG View Post

As far as the trigger on the marantz goes... does anyone have any idea if there is a fuse i can replace or did i just ****up my brand new preamp?
No idea without looking at a schmetic, and I don't have one. In the good old days, fixing it might have been as simple as replacing a 10 cent transistor. Now I suspect it means replacing a surface mounted IC.

You might want to verify that the trigger is dead with a volt meter set to DC.
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