Gino Robair is former editor of EM

Gino’s Big Adventure: Building a Personal Studio, Part 3

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Part 1 | Part 2 | Part 4 | Part 5 | Part 6 | Part 7

Electricity

One of the biggest issues in any studio, whether it’s for personal use or for hire, is the electrical setup. For many of us, the home studio is relegated to whatever room (or part of a room) is not being used by other inhabitants of the house. Consequently, we share the electrical panel with the household appliances and other sources of line noise. It’s not always easy (nor inexpensive) to isolate our gear from the noise pollution in the electrical system, so usually we just live with it.

Before we started our remodel, my studio was in a small in-law unit behind the garage. Besides being uninsulated, and therefore nearly uninhabitable in the middle of winter and summer, it didn’t have grounded power when we moved in. I eventually had a ground rod installed and wired into the electrical panel, but the house’s electrical system remained underpowered overall, and the results could easily be seen and heard. But that’s about to change.

Now that the framing has begun and the project is steaming forward, I wanted to get some general advice that would help me get the best performance from my studio’s electrical system, from the ground up, so to speak.

I decided to call Garth Powell, Senior Product Designer-Engineer at Furman Sound, to get answers about any potential issues and pitfalls, from an engineer whose job it is to mitigate them.

Powell was adamant that before you begin considering the kinds of products that a company like Furman makes, you want to make sure you have as clean of an electrical system as possible, depending on what you have to work with. That means your audio and video equipment needs to be isolated from the rest of the household’s circuits.

Of course, the best option is to have a completely separate power line coming in from the street, but Powell says that solution is cost-prohibitive or impractical for many people.

“The easiest thing to do is to create a parallel subpanel from your home’s main 240V, split-load panel,? he explains. “One side of it, L1, will have a bunch of circuit breakers versus neutral that create the 120V in one phase. L2 will have another set of circuit breakers with 120V on the other side and phase.

“It’s important to keep all of the studio equipment on a different phase than the one that lighting and appliances are on in your main home,? Powell continues. “The electrician may argue that you’ll want to balance the load [current draw] to the extent that you can: It’s hard on the transformer, and it can be hard to get a uniform 120V, if one part of the phase is eating up 80 percent of your capacity [the appliances], and the other phase is eating up 5 or 10 percent [your studio gear]. They want it a little more matched than that.

“But I’m always willing to let go of perfect symmetry there,? he adds, “in favor of making sure that all of your gear is on the same phase. So that as you have even slight brown-outs and surges, everything is coming up and down together. And ideally, everything is referenced to the same voltage versus ground, so that you don’t have ground [current] loops stemming from voltage drops between different grounds—when referenced to neutral and line. This is what causes 60 cycle hum and buzz coming through everything.?

Once the panel is in place, and I have my A/V gear on the same phase, Powell recommended that each outlet, or duplex, should be a dedicated 20 amp circuit, using high-quality, hospital-grade, orange-colored outlets, such as the ones sold by Hubbell. He suggests that I have them wired with 10×3 Romex, rather than the 12×3 Romex that is usually used for 20 amp circuits.

“Although 10×3 Romex is used with 30 amp circuits, the resistance will be lower when you use that gauge of Romex with a 20 amp system,? Powell notes. “The lower the resistance of the ground, the less of a chance you’re going to have a large differential between two separated components, and therefore, breaking into a circular ground loop. The second thing is that amplifiers love a low-impedance path. If you raise the impedance path, they’ll current compress, and you’ll have instant mud and decreased dynamics.

“You have three wires: line, neutral, and ground. For it to be a truly dedicated 20 amp line, those three wires must connect, using Romex, from the duplex straight back to that panel’s circuit breaker. It shouldn’t share or touch anything else.?

When I asked if the panel causes any issues, he added “The circuit breaker itself is not going to add resistance or affect performance. The only thing that’s really going to affect the performance is the quality of the outlet and the quality of the wiring, and making sure the electrician used good techniques and everything is tight, and so forth.?

Star Ground
But even with dedicated lines to each outlet, he recommended I use a star-ground system for my gear, where everything is ultimately connected to one outlet.

“The gold standard is a star ground,? explains Powell. “For your power or for your signal, every ground comes to one point.? That means all of the gear should be plugged into one duplex, with a series of power strips branching out, in parallel, from one source. That suggests a metaphor!

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Here’s an example of a star ground setup, using the tree trunk and limbs metaphor: Imagine that the outlet is the tree trunk and the power strips plugged into it are the branches.

“Think about the trunk of a tree,? Powell suggests. “It doesn’t matter if one of the branches is a lot longer than the others: As long as they’re both coming to one trunk, you’re okay. And that’s your star, because even as voltage is fluctuating up and down, everything is coming back to one potential—all the grounds are coming to one place. One can’t modulate the other.?

Won’t I run out of power from that duplex, once I plug everything into it?

Powell says not to worry. “With today’s digital audio workstations, plus a couple of computers, a small mixing console, a bunch of processors, and a couple of powered monitors for listening, the whole thing is probably going to be well under 20 amps.?

“And if they are low-resistance, dedicated lines all going back to the same phase,? he adds, “and you’re fairly careful about this, the chance of having a ground loop is very, very low. You’ve done everything you possibly can that’s reasonable.

“If you still have a problem, you can go into exotic things like isolation transformers and ground strappings, to try and lower the resistances.?

Go to the Pros
If you plan to have any major electrical work done for your studio, Powell says it is imperative that you use an electrician who fully understands what a studio requires and who respects the needs of a recording engineer or musician. He recommends looking for one who has done work in a broadcast environment, and suggests contacting an engineer at a local radio or television station and asking them who they use.

An electrician who has experience with wiring studios will also be the person you’ll want to consult with before you sink a ground rod. Soil composition and local climate conditions play a big role in the effectiveness it will have on your electrical system, and the person doing the work should understand what’s at stake. I recommend reading this interview with Arthur Kelm of Ground One AV, Inc. in Mix, where he talks about the issues around treated ground rods and related topics.

“If you have a really good, professionally installed ground,? explains Powell, “you can see your noise floor go 20dB lower than it would be with the conventional ground rod that the average electrician is allowed to do by code. Remember that code was never meant to have anything to do with the quality or performance of electronics. It all has to do with meeting fire code, which comes from the insurance industry.?

I want to thank Garth Powell for his time and valuable insights. Check out the links below, which cover a variety of electrical issues in greater depth.

Cool Links
Knowledge and Power

On Solid Ground

Battling Medusa: A professional approach to studio wiring.

Planning Your Ideal Recording Space

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Related Topics: Robair Report

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