Clean A/C power outlet?

[daz]

In studios you'll find orange colored A/C outlets that are orange to denote that they are clean power, IE: filtered so no noise is in the line as far as i know. Will this do the same thing?

CyberPower CP425SLG Standby UPS - 425 VA/255 W - CPU Solutions

If not, what will?

[nosaj]

Look for a line conditioner.
Amazon.com: Line Conditioners

[g1]

I thought the orange meant isolated ground but I could be mistaken.

[daz]

As could I....i was told orange was clean power years ago. Whoever told me could have been wrong.

By the way, i have 2 more questions...are power conditioners and line conditioners the same thing? Will either or both do what i want, IE: rid the outlet of any noise that comes thru amps i plug in? I plug amps into this outlet and there are these random noises that come and go that sound like devices such as air conditioning going on and off. Will a line or power conditioner eliminate those?

[R.G.]

I did a couple of articles on AC power cleanness back when I was writing a column for Premier Guitar. Be aware that advertising-speak is alive and well in the power add-on market. A power conditioner/filter/cleaner/whatever may be as little as one MOV and a few capacitors. Or it can be really clean. As a side note, the propensity for humans to think of the label as the thing itself is what makes us such suckers for advertising, I believe.

If you want clean, you have to know what clean is and how to measure it. If someone says "clean" means "isolated ground", it does - to them. If you think it means "no spikes and RF noise from fluorescent fixtures" then you'll be disappointed in the "clean" outlets from that first guy.

To get various degrees of clean from whatever AC power you have coming in, you need to worry about:
- distance from sources of AC power line pollution in feet/meters of wire back to the noise source; don't build a studio in an area where there are lots of universal AC/DC motors, welders, or refrigeration units, and preferably not where there are fluorescent bulbs (which will be impossible after 2012 when incandescent bulbs become illegal in the USA - they're all fluorescents) or dimmers. Or computers with their switching power supplies. Or wall warts, which must be switching power supplies because of the same logic that gave us freedom from incandescent bulbs.
- If you can't get distance, get attenuation. Shunt the line with things to "short out" the hash. Line-rated AC capacitors do this to some degree. MOVs clip off the worst of the spikes. This is what you get in the cheapest AC line conditioners/filters/etc.
- If that's not enough, get some impedance in the line before the attenuation. That is usually in the form of inductors, common mode chokes, and so on. Better line filters/conditioners do some of this.
- If that's not enough, get some transformer isolation from the AC line, and convert the transformer into a bigger, burlier filter. Isolation transformers do this. If you buy a constant voltage transformer (or ferroresonant, or regulating) transformer, you get some deep isolation from the line because the transformer itself is acting as a big inductor/capacitor filter to squash the hash out. A studio with its own isolation or better, ferro transformer supply is a long way toward clean power.
- If that's not enough, generate your own power, and tinker the generator to not be noisy.

Power conditioners and/or line conditioners and/or power filters are, in the immortal tradition of William Jefferson Clinton, whatever their makers say they are.

[Mark Hammer]

Question: Assuming they are capable of handling the current requirements of whatever is plugged into them, what advantages might power bars directed at computer users (at least those who haven't gone totally wireless) hold for us musical types?

For example, back in the "good old days" when people would use modems, it was not uncommon to see power bars being sold that had all sorts of EMI/RFI filtering and spike protection. I would imagine those are increasingly consigned to the bargain bin as more and more people start to say "What's a cable?"

And if there IS something useful for us in there, what are the limitations on its usefulness, and what might it need to be supplemented with to "do the job"?

[km6xz]

No, the UPS will not produce noise free power, that is not its job. The UPS is a backup power source, an inverter that will run on batteries if the mains fail. The inverter produces 120 volts ac of unknown purity from the standby batteries.

More than ever, there are noise generators connected to the power sources and in the air as magnetic or electromagnetic radiation that can impact sensitive equipment.
In my studio the control rooms ran off large heavy, and noisy constant voltage transformers, one for each control room and studio room and their associated iso rooms. You can find them surplus occasionally for low cost. They need their own room and cooling because they generate heat, and they buzz loudly. They can create a steady output voltage, low harmonics if of later design(60s -70s). They are not used as much anymore due to their cost, weight and audible noise however. You can get sine wave inverters not that are very clean and offer excellent regulation and isolation as good as the constant voltage transformers. These regenerate the AC by taking mains current, turning it into DC and using that to power a sine wave generator and power amplifier that can supply high current at 120 volts and precisely 60Hz line frequency, or 50hz as the case may be. Constant voltage transformers are made for specific line frequencies and protest if driven by generators or mains with slightly off frequency AC mains.

There is a trend towards balanced power which is naturally pretty good for noise reduction. It converts the whole power system of the studio to balanced 60 volt lines which are out of phase with each other. The highest voltage you might be subjected to if you came into contact with a power wire would be 60 volts, so there is also a safety benefit.
What sort of noise floor do you have now and what is the noise spectra? AC mains are not the only way noise gets into systems. RF noise is getting worse by the day since we are immersed in strong nearby electromagnetic fields, and more every day. What type of studio and what is the design goal noise floor?

[R.G.]

Question: Assuming they are capable of handling the current requirements of whatever is plugged into them, what advantages might power bars directed at computer users (at least those who haven't gone totally wireless) hold for us musical types?

For example, back in the "good old days" when people would use modems, it was not uncommon to see power bars being sold that had all sorts of EMI/RFI filtering and spike protection. I would imagine those are increasingly consigned to the bargain bin as more and more people start to say "What's a cable?"

And if there IS something useful for us in there, what are the limitations on its usefulness, and what might it need to be supplemented with to "do the job"?

It's one of those devil-in-the-details things. Power bar/filter setups for computers are trying to prevent things that would make a computer glitch. So they usually have three-MOVs-and-a-cap if they are cheap. Better ones include some inductive impedance before the MOVs. Better still might have some common mode chokes, more caps, etc. They pretty much fit into the continuum I mentioned.

Filtering power lines is much like filtering any signal. You want some series impedance to keep surges at bay, some shunt impedance to shunt the worst offenders to ground (or across the signal lines if differential) and a juggling of the impedances to keep out the signal frequencies you don't want. The only quirk with power filtering is that you basically want only a very narrow band of frequencies, and you have to use components which can handle kilowatts, not milliwatts. The little hash-filter bars are not necessarily useless, but they are not terribly helpful for other than line buzz, either.

The best "filtering" always comes from setting up some power reserve pool, then arranging for the incoming dirty line to pump the pool full and the outgoing line to release it at only the voltage/frequency you want. In fact, that may be the *only* way, now that I think about it. L-C line filters do this in the E-field of the caps and the M-field of the inductors. They are limited in that the storage pool is only a few milliseconds deep. Ferroresonant transformers have a big, burly L-C storage pool that's a few AC cycles deep. Battery setups which generate clean(ish) sines are a few minutes deep. A motor-generator may be some hours deep.

I was told of a hospital back in the 1960s that wanted to be sure their cardiac operating room would never have its lighting even glitch or blink if there was a power interruption. They put in an eight-hour long cast-iron flywheel. Incoming AC power spun up the flywheel, which ran constantly. The output of the flywheel was as constant a speed as anything a non-government could afford, and that ran generators for the operating room. A full loss of AC power left the flywheel to spin down. The lights got dimmer, but never so much as blinked.

Modern electronics let us construct constant voltage/constant frequency outputs to our taste, if we want to go to the expense.

But I'm wandering. The simple filters are better than nothing, but not hugely.

[Mark Hammer]

Thank you, sir. I can always count on you.

Is there any sort of classification of audio devices wherein THIS group only needs X and Y, in the way of power conditioning, but THAT groups needs X+Y+Z?

I'm looking at this in terms of a musician without unlimited funds who says "Well, appliance X can only power 6 devices, and I can't really afford another one of them unless it is absolutely necessary."

[Tom Phillips]

I'm throughing my vote for balanced power that km6xz mentioned. It is usually used in custom installations for a studio. However, if you are willing to experiment it is possible to build a small unit that can be used with a single amp. It's not the most convenient way to go but it is reported to produce amazing results.

[R.G.]

Thank you, sir. I can always count on you.

Yeah - but for WHAT?

Is there any sort of classification of audio devices wherein THIS group only needs X and Y, in the way of power conditioning, but THAT groups needs X+Y+Z?

I'm looking at this in terms of a musician without unlimited funds who says "Well, appliance X can only power 6 devices, and I can't really afford another one of them unless it is absolutely necessary."

Oh, sure, ask the pertinent, logical question again.

That made me sit and think for a while. My quick-draw reaction was "no way to say", but then I realized the silliness of that response.

I think the things that matter in choosing how much to worry about clean input power for a device are (1) how immune the device is to power disturbances on its own, a sub-consideration being whether it internally regulates and cleans up its power supply on its own (2) how immune the device is to ground disturbances, this being different from (1), and (3) how much sheer power it needs. Probably one should worry about transient-induced damage, too.

If a device uses little power and has internal regulators and filters, and is not coupled to other things which could cause ground-noise issues, what you feed it doesn't matter a lot. If you want to use it in situations where the slightest disturbance is both audible and worse yet recorded, then what you feed it matters a lot, as witness studio practice. And running a few 10KW PA bins at the same time is a whole different animal from running a couple of guitar dirt-box pedals.

There is a clear division line between power conditioning when the raw amount of power is down in the range where signal-level parts can clean it up as opposed to where the power is large enough that you have to start worrying about component heating in the power filtering parts. There is another line where the thing needs (as opposed to can use) it's own power transformer, and another at about 200W and up.

In the lowest range, you're worried almost entirely about transients and noise fed in from the power line, and protection. For this range, the surplus modem-filter strip is good. It's intended to get high frequency hash out of the power line, and to clamp spikes. For these low-power devices, you can easily and cheaply add regulators and filtering inside the device to suppress power-line noise as needed. The higher power range needs filtering and suppression parts inside that are more expensive and custom tailored because they have to withstand heating. Small amps qualify here if they're used in sound-critical uses, like studios. When things have their own power transformer, the modem-filter strip is still useful up to a couple of hundred watts, but it's not sufficient on its own. The internal power supply needs attention for getting clean power. Above a couple of hundred watts, you start worry about what the device's internal power supply is putting back out on the power line. Well, OK, you have to worry about that some with any -switching- power supply, even low powered ones, but the modem-filter helps with that in many cases.

For truly noise-critical applications, you get into external isolation transformers. The balanced-AC-power thing is good because it forces the AC power lines to be twisted-pair(ish) with small loop area, so it helps suppress M-field transmission, and at least partly because it forces the power distribution net it supplies to be small, and thought about in noise terms on its own. Those help a lot with keeping AC noise out because they force a number of other related things to be done. Just going balanced-AC doesn't confer all that much immunity to AC power line disturbances other than what the transformer does as a side effect of being a low-bandwidth device.

The next step up is a ferroresonant/constant-voltage transformer. The ferro, as it's known in the transformer biz, is a fairly amazing device. It's primary defects are that it's heavy and expensive. But in return for tolerating those issues, it offers both voltage regulation on the AC line and also a very substantial decoupling of any hash from the power line or going back to the AC power line as line pollution. For really critical work, a big ferro with enhanced ("medical grade") isolation and balanced AC out is about as good as you can get without generating your own clean power. This is because the ferro is a *big* resonant circuit, and whatever goes in or out is heavily filtered by the resonance. And the resonant parts are *big* and *high power* rated.

I'm sure I've missed part of what you were asking.

[tedmich]

real huge iso-transformers do wonders for touchy lab equipment but are quite spendy, you can try a nice Corcom type filter, which is all the silly MONSTER and other "conditioners" usually have.

Or try a Bybee Quantum Purifier (kidding, but their WEB page is a hoot!)
BybeeTech - Quantum Purification

[Tom Phillips]

...Or try a Bybee Quantum Purifier (kidding, but their WEB page is a hoot!)
BybeeTech - Quantum Purification

Or, from the Bybee website "Bybee Golden Goddess 'Super Effect' RCA Bullets The GG SE RCA Bullets are the highest-performance plug-in upgrades for RCA interconnects. Each Bullet comprises a 4-inch-long carbon fiber tube containing an Eichmann RCA plug and jack, SE Internal Purifiers on both the + and - legs, and 14K gold ribbon wiring. Their performance exceeds considerably that of the entry-level Magic Bullet II. Retail price: $2,495/pair"

Wow. I wonder what these will make your Fender reverb sound like?
I guess this is fodder for another one of those wacky audiophile discussions.

[R.G.]

Sadly, it seems that there is nothing to which purveyors of magical mystery parts will not stoop to collect the universal tax on naivety and gullibility.

It makes me wonder how "performance" is measured. Perhaps monetary return on each sale. For $2.5K per pair, you only have to find a few ...er, customers... to make it very worthwhile to write over the top claims on your web site.

[tedmich]

I am beginning to think audiophool sales is a karma free endeavour; you cause no real harm (unlike homeopathic/counterfeit medicines) and simply facilitate some naive rich guys fantasy without exchanging bodily fluids.
No one will ever sue you and no law enforcement agency would waste the time to bust you.

Definitely less bad karma than these guys:Iraq Swears by Bomb Detector U.S. Sees as Useless - NYTimes.com