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Killing power to amps while their turned on


enhanced250

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Im being overly cautious so before I do anything im asking ALL questions so my equipment doesnt get ruined. I have Marantz MA500 amps that Im going to plug into the switched section of a power center. It will be triggered on by my Denon 12v out.

Question is .....the amps power will be constantly in the ON position and will be turned on and off by cutting the power to the surge protector naturally. Will this cause a problem or is this any different then hitting the power button on the front?

Essentially this setup would be like pulling the plug while the amps are witeched on and plugging them back in to power them up.

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  • 3 weeks later...

Turning it off shouldn't be a problem, turning it on can be. Many power amps have a huge surge when you turn them on, and add on the rest of your gear and the switches on many cheaper powerbars etc don't take that sudden in-rush of current very well... or even the relays on many surge supressing units. Just because it works for now, doesn't mean it will work very long (or with different gear).

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Speaking from an audio nut and electricians point of view, it many times is a big problem. You can easily burn out the contacts in a cheesy power bar, and even better ones don't like the surge of a serious power amp, or two... I've burned out many high end surge supressors with simply too much in-rush current (they're not designed for that, they're designed for phase to phase to ground in-rush current).

Many decent power bars on up to full sized rack surge units, like Furmans, have "always on" plugs for that reason (among others, like DVRs etc). Your amp always has standby power when the trigger turns them on, so no mad in-rush current, the caps are charged (or at least partially so).

If you're turning on a 60 watt stereo, who cares? But if you're turning on a quality high current multi channel amp... there's a mad in-rush current, and no soft start protection from the amp's power supply to soften the in-rush.

Heck, even ceiling fans often burn out cheap light switches (you hear a popping sound as they die).

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Speaking from an audio nut and electricians point of view, it many times is a big problem. You can easily burn out the contacts in a cheesy power bar, and even better ones don't like the surge of a serious power amp, or two... I've burned out many high end surge supressors with simply too much in-rush current (they're not designed for that, they're designed for phase to phase to ground in-rush current).

Many decent power bars on up to full sized rack surge units, like Furmans, have "always on" plugs for that reason (among others, like DVRs etc). Your amp always has standby power when the trigger turns them on, so no mad in-rush current, the caps are charged (or at least partially so).

If you're turning on a 60 watt stereo, who cares? But if you're turning on a quality high current multi channel amp... there's a mad in-rush current, and no soft start protection from the amp's power supply to soften the in-rush.

Heck, even ceiling fans often burn out cheap light switches (you hear a popping sound as they die).

You're speaking in generalities here. You really think that using a 12 V trigger from a 125 Watt amp to a good powercenter will burn out the amp? Most amps are designed to be used with a 12 V trigger.

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you have to look at the schematic of the MA500 amps. If there's a small value capacitor wired across the on off switch, then your proposal would defeat that. Some makers of high current audio gear wire a capacitor across the on off switch to serve as both a warming circut and a thump protector.

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If you turn the amps off like that be sure to lower your volume alot or off, or you may ruin your pants next time you turn it on. [:|]

Once I was using the built in pink noise to balance the speakers, and forgot and switched it to another source without lowering the volume, don't know how I didn't blow something up ?

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No, I'm saying turning your amp on and off with the rocker switch on a power bar will burn out the switch.

Agreed. That wasn't the original question. See first post.

Sorry, but that's how I read; "Question is .....the amps power will be constantly in the ON position and will be turned on and off by cutting the power to the surge protector naturally."

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I am racking my brain trying to figure out why you would want to turn your system on and off using that method... You already state that the amp will run off a trigger from your pre/receiver... If you kill the power to your pre/receiverand tv, you will probably loose all of your settings everytime you power up.

I have been running my amp off the trigger on the pre for more than 10 years, never had a problem with it.

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Many people want a one button solution to turning everything on and off, and that does it... but if he's doing it the way I think he is (and I may be wrong... it won't hurt the amp... if that's the original question), but if he's got some serious gear or lots of gear on the same bar, he can burn out the switch and/or switching in his power bar or surge unit.

As far as your gear is concerned, it is very much like a power outage,.. (though a power outage can come back on with all kinds of high voltage spikes that your surge suppressor should hopefully eat up).

For your switch, it is very different. A closed (turned on) 15 amp switch/contact/relay can handle a tremendous amount of short term current), so a power outage on a closed switch doesn't matter. But as no switch/contact/relay is an absolutely 100% instant-on, there is a point as the switch closes that resistance goes from infinite (the switch off)... until like a microsecond before... that the switch goes from infinite to less then infinite... to a bit of resistance, to a bit less, to a bit less to the switch being fully on with the switch as close to zero resistance as it gets, So the high current in-rush is not only way more the the 15 amp switch can handle, plus added resistance, plus it also wants to arc across as the switch closes, and that also burns the contacts, making it worse for next time. It's an accumulative fault, it gets worse as you do it more often.

So that's what triggering is for, like you're doing, a lot of stuff always has some things charged up in a standby mode (most of the time, only partially), so you don't have that huge in-rush current, that many times can temporarily dim your lights or even blow a 15 amp breaker, even if everything runs fine once it's on, depending on the gear of course. Have you ever un-plugged a vacuum cleaner when it's running and seen a big spark, amps are kind of like that, but back-wards, they do it when you plug them in hot, charging those big capacitors in the power supply. Power-on in-rush current is way more then you'll even draw when the unit is running.

Of course you can turn your amps off with a trigger, turn off your preamp's actual power (not just standby), then shut off the power bar... (and you should do that when going on vacation and such). And to turn it on, do the reverse, but after turning on the power bar, wait a few seconds (1 or 2, that's all it takes, the in-rush current is really high, but really fast. Things charge up to almost full charge in a moment, then the current goes way down), then wait a second to turn on your preamp, and it's even better if your preamp starts from a powered off - standby mode, (though most don't seem to).

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