Measuring Power Quality

[adamlloyd]

Hello,

I've been reading numerous threads on this topic but couldn't find a direct answer to my question.

What is the best way to measure power quality/voltage coming from your wall sockets? A multimeter? Any specific kind/brand known to be the most accurate?

Also, I've read that it's best to power all units from the same source? What exactly is the problem with having, say, 2 sources? I guess I'm totally clueless as to the reasoning here, although I believe it has something to do with noise floor and grounding (this is something I've ignored for years and just got lucky with; I'm trying to learn the details now as I'm having to relocate my project studio to a new building). Would it be acceptable to have all units involved in the recording chain (preamps, converters, pro tools interface) powering from one source, and monitors, computer/LCD screen, etc, powering from another?

[If this has already been outlined on another thread I missed please let me know, thanks!!!!]

[nosebleedaudio]

A meter will only measure voltage, not the quality of the AC.
Most AC sources have a small to high amount of distortion on the AC.
I do not recommend doing this your self UNLESS you know what you're doing and know what you're looking at, and having the test gear to do it.
People probing around AC that are not qualified can be a BAD idea.
On the same leg of the AC panel is what people are referring, this can make a BIG difference in hum/grounding related problems.

[adamlloyd]

Originally Posted by nosebleedaudio

On the same leg of the AC panel is what people are referring, this can make a BIG difference in hum/grounding related problems.

Does this mean every electrical product needing power? Or just the ones involved in the recording chain (keys, converters, preamps, computer)?

Should I have the AC voltage and distortion measured at the new place, by someone else? How much distortion is "ok" and what are the side effects of AC distortion, besides DC offset? (I think)

I've been reading about power conditioners and voltage regulators on here, and I know some people consider them unnecessary, so I'm trying to get a grasp of what exactly they're supposed to be fixing and why.

Thanks!!

[tINY]

Really, the "quality" of the power is pretty easy. What is the voltage, how does it vary throughout the day and is there noise on it. Most of your decent power conditioners will fix these problems if you have them (and usually, you don't need them).

What you want to look for is the current/voltage on the ground. The best, standard thing to do is have a technical power outlet installed with a home run ground.




-tINY

[A27Hull]

Originally Posted by tINY

What you want to look for is the current/voltage on the ground. The best, standard thing to do is have a technical power outlet installed with a home run ground.

What is a good way to test for voltage/current on the ground?

What do you mean by technical power outlet...etc.?

[nosebleedaudio]

I would suggest doing some REAL research on this subject, harmonic distortion on your AC circuits for example..
You will find that in some places such as "Clubs" the AC can be so bad it has destroyed audio gear, and one such case they WERE using a high end conditioner...

So it depends...
And a Tech circuit is simply a dedicated AC outlet with a dedicated Ground, NOT the ground obtained via the conduit...
And also NOT using a common neutral.
This is known as a "Isolated ground circuit" It does NOT get its ground thru the conduit, if in a commercial bldg.

And if you need more than 2 circuits you simply make sure they are on the same Leg or phase in the panel, you skip a breaker slot.
A good electrician will understand this.

[Matt Syson]

Hi
For safety regulations (and by extension, insurance which may become void) your studio ground MUST be connected to the incoming safety ground.
You can then have a local connection to ground rods, mesh, whatever which can (depending on location) help with any 'odd noises'.
If your equipment develops a fault and dumps power into your 'damp soil' ground it may not then trip the breakers as it should. I have seen this done and there was about 90 Volts AC on what should have been ground but instead was heating the soil under the studio.
You MUST make your installation capable of complying with safety regs.
Matt S

[A27Hull]

Thanks

[adamlloyd]

I think I need an electrician to evaluate the conditions at my new building before I consider what exactly I need. Should any electrician be qualified for this?

[tINY]

Should be, but I wouldn't count on it.

Call a Film or sound studio and see if they can refer someone.




-tINY

[mikeg]

Try to find an electrician that has done work for hospitals, doctors office, dentist, etc. The regs for medical is tighter than for a basic industrial install. These guys will know what, how, where to do this.

[adamlloyd]

Anybody know of any good electricians in Los Angeles/Hollywood they could recommend?

Thanks!

[nosebleedaudio]

Originally Posted by adamlloyd83

Anybody know of any good electricians in Los Angeles/Hollywood they could recommend?

Thanks!

I would call a few studios and ask them.
Most studio owners that have been around know how important it is to have someone that has done "Studio wiring".
A good electrician should know how, but will add that some studios have/still use grounding methods that are NOT to code...

Like Tiny mentioned your AC might be just fine, the problem could be something a normal conditioner will NOT correct, or can.
AC noise, spikes, surges, dips ect can occur at odd times during the day, so accurate monitoring requires being across the AC for 24 to 48 hours to really know what is present.
Will also add that most garbage comes from within your own building...
On the same main AC drop or feed.
I would not panic, you would be surprised how many places have problems and it's just not severe enough to cause obvious problems yet...
It's like the Voltage on many Gtr amps (On the chassis with respect to ground) with NO AC ground connection, until someone gets shocked its considered safe...

The first place I would start is getting an Isolated ground circuit for your audio, 2 if required.
I prefer 2- 15 amp circuits, still using 12/2WG.
An "Isolated" ground DOES NOT mean it is not grounded to the main AC ground point... Simply means its ground wire is a dedicated wire run back to the AC panel.
Some electricians still do not understand this.

[Wavebourn]

I once used a ferro-resonant voltage regulator. In one village a keyboard sounded with a huge tone modulation, like a voltage was low and floating, but lights on the stage were bright and stable!
I measured a voltage in outlet, it was rock stable 240V!
Then I measured it after my huge regulator, and found it wildly floating.... What I've found, their electric station (a huge marine diesel generator) produced stable 240V, but a frequency was floating!

It was a long time ago, in a deep Siberian forest.

But here in USA I've discovered another problem: lot of domestic appliances consume one half-wave causing as the result DC bias...

[BOWIE]

Originally Posted by adamlloyd83

Anybody know of any good electricians in Los Angeles/Hollywood they could recommend?
Thanks!

Asking studios is a good idea. I've known many electritians and none of them knew anything about audio or what constitutes a suitable electrical environment for audio.

[adamlloyd]

I'm thinking of getting a small UPS unit, but I'm confused as to what all would need to go into it (besides converters, preamps, ... computer? monitors?) and what doesn't need all the protection. I'm also not sure how to calculate how many VAs I need...