Surge Protection for Audio System

[tom baker]

I am helping with the electrical at my church which will have a good bit of audio equipment, mixers and amps. We installed a 24 ckt small feeder panel with isolated ground - OK go easy on me here - it makes sense with audio equipment to keep all the audio gear equipment grounds at the same potenial.
There is a very sharp audio guy to who I mentioned that I would like to install a SPD (A Leviton panel mount) at the feeder panel and he had done some research on this, saying that the MOVs in a typical SPD can conduct or break down causing noise and problems in the audio equipment.
He mentioned this mfg
http://www.surgex.com/

They make a series SPD
http://www.surgex.com/products/iControl.html

There are a lot of white papers on the surgex website, seems like there is some justification to the series SPD theorey for branch circuits.

What I know about audio systems is that its important to get the grounding right to eliminate hum and noise.

Could I install a Leviton panel SPD at the feeder panel and be OK?
Would the SPD ground go to the panel ground or isolated ground?

 

[Speedskater]

While Surgex makes a very nice product and Jim Brown of Audio Systems Group wrote their white paper (Jim Brown is one of the very top people on audio and AC power interfacing). I still think that a Leviton panel SPD at the main panel should fill your needs.

For some interesting reading, see:

The Bill Whitlock of Jensen Transformers Seminar paper
http://www.jensen-transformers.com/an/generic seminar.pdf

The Jim Brown of Audio Systems Group white paper
"Power and Grounding for Audio and Audio/Video Systems"
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf

"The TRUTH" from ExactPower of Middle Atlantic Products
http://www.exactpower.com/elite/wpapers.aspx

or a different version of the same paper

"Power White Paper" from Middle Atlantic.com
http://www.middleatlantic.com/power.htm

 

[dereckbc]

More Than One Way To Skin a Cat!

More Than One Way To Skin a Cat!

Tom pardon my delay, very busy at work and in a class.

I recently last year did the design work for my new church. What we did is went the ole fashion way, or what I do in data centers, except on a budget. (In a data center we would use a PDU with filtering, bells, and whistles) We just installed a regular plain ole dry type transformer feeding the primary with 480 delta, and using dedicated 20 amp SG circuits to all the AV locations. The point of doing it that way is to establish a new N-G bond point, and eliminate all common-mode noise which is what you are after. This establishes the new single point noise free ground you are shooting for.

In the transformer panel we just used a plain old brute force 3-mode (L1-N, L2-N, & L3-N) SPD employing both MOV and SAD.

I understand the theory of using a series active SPD downstream from the main service, but IMO is a bit of over kill and putting a band-aid on a problem that can be better dealt with by using an isolation transformer. Now with that said it is true MOV’s can become leaky, but you are going to know it because you will hear the frying and popping sound. But using hybrid with both MOV’s and SAD’s pretty much eliminates the MOV’s from becoming leaky. Usually when an MOV fails, it fails open and let’s the magic smoke out.

To answer your question in your PM, you want to use a SPD made for IGR panels. They have the extra mode so you end up clamping between IG and EG. They are rare birds and fairly expensive. IMO it is less expensive and much more effective to use an isolation transformer with SG branch circuits…