On Mon, June 1, 2015 10:12 pm, Glen MacArthur wrote: > I'm in the middle of building a new recording studio and soon will be > starting to rough-in the electrical wiring, the studio is not very large > but will have a separate uncoupled control room and a studio > floor/rehearsal space. I'm curious what the prevailing wisdom is on using > shielded wire (or metal conduit tubing) for the electrical wiring.. This is a good overview of power systems interaction with audio systems written by Jim Brown of Audio Systems Group: http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf Look for the section titled "Preventing Magnetic Coupling" for a description of ways to minimize magnetic coupling of power frequency noise. > I'm in Canada where we use 120V AC In North America you can also use 240V AC single phase, which has the advantage of using only half the current (reduces magnetic coupling) and has anti-phase voltages on each power leg (can help reduce leakage currents onto neutral and safety ground). In short, twisting the power legs helps, and running in metallic conduit helps, thicker conduit more than thinner, so rigid still has better low frequency shielding than EMT. Your labor costs go up a lot if you run rigid conduit, even EMT is probably pretty high labor costs. > would be 'BX Cable' which is insulated wiring in a flexible corrugated > aluminum shell Don't bother with that unless you have to because of safety considerations. I don't think you can use Romex in commercial installations, there needs to be some type of armor (excuse me, I guess that would be armour in Canada) to protect the wiring from insulation cuts. > and the last option would be metal conduit which is There are actually two variants of metallic conduit, rigid which is thicker walls, and EMT, "electrical metallic conduit" which has thinner walls and is therefore easier to bend and install. That paper goes into details. Don't overlook that the shielding is cumulative, so if you can afford the labor costs (or labor time if you are installing the conduit yourself) there could be advantages to using steel conduit for the power and the audio cabling. Personally I don't find that power line coupling into line level twisted pairs is usually a problem, and having your microphone lines well shielded doesn't really help when the problem is power line pickup in your guitar pickups. > A second related question: Is LED lighting better than CFL for noise? I am > aware that dimmers are always a bad idea so I will be avoiding them and > I'd prefer to use LED unless they are worse for causing noise.. I have not seen any definitive tests of conducted or radiated noise between LED and CFL, but they both use similar styles of power supply design, so to a first order approximation they are probably the same. -- Chris Caudle _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
