Friday, March 5, 2010

Power Conditioners and hype..

In my day job I am a service technician for a medium sized regional A/V contractor. Most of my work involves troubleshooting audio systems and optimizing performance. I have the opportunity to work with some very nice equipment in beautiful environments, like some of the local church sanctuaries around Seattle. One such system involves a church that is used as a venue for performing and recording sacred music, especially involving period correct interpretations of the music score with appropriate instrumentation. The acoustics of this church are perfect for the exquisite pipe organ and musicians; not so much for the spoken word (the two are often mutually exclusive and our job is to try to integrate sound reinforcement into these challenging acoustic environments).

Last year we erected a 25' scaffold in order to install 4 hanging mics from the very tip of the ceiling- high-quality Neumann condensers, two at about center stage and two out in front of the stage and about 12' off the floor. The cabling was run to a mixing console in the rear of the sanctuary and then fed to an Alesis Masterlink hard-disk recorder. The sound captured with this set-up is incredible, but the mics are so sensitive that they can pick up a whispered conversation at the back row!

The music director and the recordist / board operator had been reporting an intermittent noise coming through on the recordings. Intermittent problems are difficult to troubleshoot and the first time out I couldn't re-produce the problem. The second time out I was able to hear the noise through the monitoring headphones. It was a nasty intermittent buzz that varied in intensity and character. We swapped in another console and the noise went away, so I determined that it must be something in the consoles PSU and sent it away for service.

They actually did find something wrong- the phantom power supply was bad and they replaced some components. But after installing the repaired console back into the system the buzz was still there. ??!! Then I noticed when we moved the power cables around behind the desk the intensity of the buzz would vary, and this led us down the path of changing out extension cords and eliminating some cheap plastic power strips. Also, uncoiling the power cables and laying them flat under the desk took care of some more of the noise, but it was still there to a degree which was clearly audible on the recordings.

I then recommended another option that I thought would work since it seemed due to dirty power. That was installing a high-quality series mode power conditioner in the system. The Surgex SA-82 fit the bill and was ordered. These units are expensive but they really do the best job of surge suppression, and unlike MOV based surge protectors they last forever and don't dump dangerous and noisy voltage to ground. The side benefit is that because they use a large series choke to do the surge suppression they filter out way more noise and nasties on the power line than do the tiny little RFI filters found in most professional surge suppressors.

Well, it worked like a champ. All of the noise, buzz, hum and grit was gone, and the sound has taken on a more relaxed and open quality. They really do work. Check out their website for more information on how they work:

The power grid is getting noisier all the time; everything has a switch-mode power supply these days, and those CFL light bulbs they're pushing on us throw out noise too. Plus the utilities can at times send big voltage spikes into your house when working on the lines, it's happened to me! Cheap insurance to protect your stuff.

So, the hype is that these units do an excellent job at protecting your equipment at the same time cleaning up your power from noise, and are much less expensive than some of the crazy audiophile type power conditioners out there.
I think I'll get one for myself!

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