Film-Tech Forum ARCHIVE: How do you turn on your sound rack?

This is topic How do you turn on your sound rack? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Paul Vollmers (Member # 927) on 05-04-2012, 05:55 PM:

Do you just hit a breaker and everything is powered on?
Or do you power up individual items?
If so...what do you start with?
All amps at once?
So, what is the correct way to power up a sound rack?

This is for film projection..

Dolby DA-10
Dolby Digital Preamp
Dolby CP65
Rack sound monitor
exciter supply
Power Amps (7)
Dolby 24V Power supply

Posted by Victor Liorentas (Member # 5272) on 05-04-2012, 06:19 PM:

I have my CP 65 and each amplifier on a dedicated breaker.
Processor on first and then each amp on one at a time via the breakers.
Somewhere in no particular order come the cat 700 and other units.
At night the processor goes off last to avoid the boom.

Posted by Carsten Kurz (Member # 5396) on 05-04-2012, 06:38 PM:

amps last (individually or through a power sequencer). All others don't care.

- Carsten

Posted by Scott Norwood (Member # 30) on 05-04-2012, 06:51 PM:

I have never seen a power sequencer in a motion-picture sound system, but that is the easiest way to do it (and is common in other types of installed systems; the cinema people seem to be behind the times on this one).

As said above, amps go on last and off first. Turning on all amps at once will probably blow a fuse and/or trip a breaker, so they should be on separate circuits (or just use the switches on the front and power them up one at a time manually.

A while back, Brad posted that he has the electrician set up electrical panels so that breakers can be turned on in order and turned off in reverse order. This is a good idea for making a fool-proof booth.

Be especially careful with the CP50 and CP200--both of these make a loud "pop" when powered on or off and can easily blow speakers. The CP65 (I don't remember about the CP55) and later do not seem to have this issue.

Also, I prefer to have the processor wake up in non-sync, rather than a film format, as it reduces the chances of someone trying to thread the machines without checking the format and changeover state on the processor (and probably making a thump-thump in the speakers as well). Most places do this anyway, as they use the cinema system for walk-in music.

Last point: if you are showing many mono films, and you have any hiss or hum in your system at all, leave the unneeded amps turned off when showing non-Dolby films. Your audiences will thank you.

Posted by Louis Bornwasser (Member # 3063) on 05-04-2012, 08:24 PM:

4 breakers for rack in no particular order. properly designed system do not "pop." Inrush current limits breakers to 2 or 3 amps. Professional amps have an internal mute circuit to allow silent start up.

I have used sequencers, but only when fewer than 4 circuits were available. Louis

Posted by Joe Redifer (Member # 3) on 05-04-2012, 11:19 PM:

quote: Paul Vollmers
Dolby DA-10
Dolby Digital Preamp

What is the difference between these two things? Also, why do you still have a DA10? Didn't Dolby replace all of those with DA20s for free?

Also, how do you power up the Dolby stuff before you power up the "Dolby power supply"? What is this Dolby power supply? The DA10 and CP65 just plug into regular receptacles without any external DC conversion.

Posted by Louis Bornwasser (Member # 3063) on 05-05-2012, 05:38 AM:

Sounds like he may have the cat 699 reader which has no electronics. I am also surprised to see DA10. Louis

Posted by Paul Vollmers (Member # 927) on 05-05-2012, 06:20 AM:

Updated whats in the rack..sorry

Dolby DA-20
Dolby MPU-1 Preamp
Dolby 24V Power supply for preamp
XD-10
Dolby CP65
Rack sound monitor
exciter supply
Power Amps (7)

Posted by Marcel Birgelen (Member # 6801) on 05-05-2012, 06:27 AM:

If you want to power up your equipment with a delay, why not invest in one or more switched PDUs? APC offers them. You can configure aa start-up delay per outlet. They are also remotely manageable, so you can manage your equipment via a web interface or even automate the whole thing via SNMP.

Posted by Randy Stankey (Member # 64) on 05-05-2012, 09:02 AM:

Is this one of those questions where you're supposed to make a funny video of yourself using some kind of Rube Goldberg contraption to turn your sound system on then post it on YouTube? [Wink]

Posted by Monte L Fullmer (Member # 2797) on 05-05-2012, 12:58 PM:

I've seen systems with line conditioners that gradually increase the voltage and decrease per on and off conditions for high powered components.

..like a big variac.

True, it's that sudden "pop" that loves to take out HF horn diaphrams. Replaced a few of them.

-Monte

Posted by Joe Redifer (Member # 3) on 05-05-2012, 04:50 PM:

I wouldn't even bother turning on the MPU1. It probably doesn't draw a lot of current, but it's not doing anything.

Posted by Ian Parfrey (Member # 5122) on 05-05-2012, 07:00 PM:

One breaker turns the lot on with amp attenuators brought up to full after 5 seconds.
Before turn off, attenuators turned fully off then breaker.

Posted by Tony Bandiera Jr (Member # 2365) on 05-07-2012, 12:14 AM:

LOL Ian, what ancient amps are you using? And if all your amps are run wide open then you are not getting the best gain structure which will leave a lot of hiss and also make it far easier for someone to jack the gains of the processor and blow out speakers.

As for power up of my rack at home, the AMX, DirecTv, and CP650 (I need to take a new pic as my one here shows my now-retired CP-65) stay on 24/7 and are on a UPS. The DCM 10 monitor and the DCA power amps are switched on with a 25 amp solid stare relay controlled by the AMX system.

Most of the screening rooms I have done are set up the same way. My home rack is wired for 3 circuits but is powered off of one 20 amp circuit for now. My screening rooms have a minimum of four circuits, usually 5 circuits. One circuit for all the processing/sources and the others are divided among the amps and switched using the solid state relays.

The AMX systems do the sequencing according to amps on last and off first.

Oh, for cinemas I had no more than two power amps per circuit, paired off like this:

left and right, center and surround, subs (always only one amp per circuit)

For the stage channels if bi- or tri-amped same configuration but I tried to not allow all of the LF channels to pair off on the same circuit.

Posted by Chris Slycord (Member # 4239) on 05-07-2012, 11:56 AM:

quote: Tony Bandiera Jr
The DCM 10 monitor and the DCA power amps are switched on with a 25 amp solid stare relay controlled by the AMX system.

I, too, turn on equipment by looking at them very intensely. Not sure if I get 25 amps out of it, but it's worked ok so far. [Wink]

Posted by Brad Miller (Member # 2) on 05-07-2012, 12:17 PM:

Wow. I thought only Joe could do that.

Posted by Victor Liorentas (Member # 5272) on 05-07-2012, 12:46 PM:

I stare my home system into deep submission! [Smile]

It's a soft stare relay though...

Posted by Tony Bandiera Jr (Member # 2365) on 05-09-2012, 06:31 PM:

And if staring doesn't work, I have been know to resort to kicking..and if that fails then a good gay porno does the trick. [Smile]

Those solid-stare relays are not too expensive either. [Big Grin]