Powering up speakers query

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Powering up speakers query

Postby Drumstruck » Wed Feb 26, 2014 7:39 am

Seeking some advice on powering up.....

I have a pair of powered spkrs + sub - each has an on/off switch on the back - as they are behind the desk it is difficult to get at the power switch on each spkr.

I'm wondering if it could cause them any damage if I leave the spkr on/off switches in the "on" position and power them up by switching power on at the power board?

I guess the question boils down to where the protection circuit in the speaker lies - would it be wired within the switch or after it?

thoughts? advices? anyone had a spkr go up in smoke doing this?
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Re: Powering up speakers query

Postby jkhuri44 » Wed Feb 26, 2014 8:26 am

you'd need a soft start power up device to avoid surges of power going through the cone. if you have valuable speakers, i'd never want them exposed to power ons like that.
in DIY project amp builds, a soft start is connected to the power supply as a device to slowly feed power to the circuit...so i'd say its after the power switch and before the PSU. im not technical enough to explain it properly,but i know sudden power increases arent ever good for speakers.
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Re: Powering up speakers query

Postby stosostu » Wed Feb 26, 2014 9:58 am

"Usually" the power switch just applies the mains to the internal circuitry, so switching on at the wall socket would do the same thing, and if there is any 'soft start' circuitry inside the speaker amps, then it will still operate. It is highly unlikely that there is any protection circuits prior to the main switch.

There are exceptions, however, and the most common one is valve amps with solid state rectifiers, which have a 'standby switch'. This allows the heaters time to get hot before the high voltage is applied to the anodes. This is not commonly necessary in valve amps with valve rectifiers as the warm up time of the rectifier allows the heaters to get hot.

Without seeing the circuit for your specific speakers, my guess would be that powering them on at the switch would be fine, YMMV, NWGOI.
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Re: Powering up speakers query

Postby Drumstruck » Wed Feb 26, 2014 10:34 am

Thanks Bob - that was what I thought, but being a prudent architect I follow the rule of "test twice / implement once".

fyi they're KRK Rokit 3-way monitors and matching 12" sub
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Re: Powering up speakers query

Postby Kurt » Thu Feb 27, 2014 6:37 pm

Try it! If they don't Thud! loudly then I'm sure they'll be fine. If they do Thud! loudly they'll probably still be fine but it can scare the shit out of you if you aren't expecting it!
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Re: Powering up speakers query

Postby Drumstruck » Fri Feb 28, 2014 12:23 pm

Well here is the answer if you own KRK 10-3s and a KRK-12-s (sub) ........ don't do it.

Test results (using a quality power board with protection circuit):

Test 1 - Sub power up via it's power switch = no thud

Test 2 - Sub power down via it's power switch = no thud

Test 3 - Sub power up via power board (with sub switch "on") = no thud

Test 4 - Sub power down via power board (with sub switch "on") = soft thud

Test 5 - 10-3s power up via their power switch = no thud

Test 6 - 2 10-3s power down via their power switches - no thud

Test 7 - 10-3s and 12-s power up via power board = no thud

Test 8 10-3s and 12-s power down via power board (wih spkr power switches "on") = medium thud


Damn!
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Re: Powering up speakers query

Postby stosostu » Sat Mar 01, 2014 1:45 pm

There must be some sort of suppressors across the internal power switch then. Unlikely to cause any damage, but annoying, so not recommended.
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