4 ms·

You're laughing, but an arts building I worked in had a separate electrical system (color-coded outlets) for A/V equipment in its performance spaces. I'm hazy o

You're laughing, but an arts building I worked in had a separate electrical system (color-coded outlets) for A/V equipment in its performance spaces. I'm hazy on the details, but professional systems integrators apparently do believe that some components are sensitive to noise in the electrical supply, and it is useful to separate them from the rest of the electrical devices in a large building. Google led me to a whitepaper [0] which indicates that the A/V power system's interesting characteristic was probably that its ground is bonded to building ground at exactly one point. Apparently in this design it's undesirable for an A/V system device to accidentally connect to the main building ground or actual "earth," which jives with my experience that a component accidentally plugged into a regular outlet created an unbearable hum in the audio signal (i.e. the grounds were substantially different). [0] http://www.surgex.com/pdf/PowerGround.pdf http://www.surgex.com/pdf/PowerGround.pdf

DINKDINK 10y ago
Why not just use a UPS (Uninterruptible Power Supply)?
- LeoPanthera 10y ago
  Even a UPS is probably overkill. A Power Conditioner should be sufficient. https://en.wikipedia.org/wiki/Power_conditioner https://en.wikipedia.org/wiki/Power_conditioner
- mirimir 10y ago
  My thought, exactly. With a dual-conversion UPS, I don't believe that there'll be any noise from the power grid.
- metaphor 10y ago
  Audiophile Mistake #1: Proposing a sensible solution to a problem which doesn't exist.
  - matwood 10y ago
    Like wooden vs. plastic volume knobs? :) http://bobbyowsinski.blogspot.com/2012/05/485-volume-knob.html http://bobbyowsinski.blogspot.com/2012/05/485-volume-knob.ht...
  - LeoPanthera 10y ago
    It's not completely outlandish to imagine that noisy power could cause noise in the audio output of an amplifier. I would hope that any good quality amp would filter the incoming power, though.
    - superuser2 10y ago
      I'm guessing that good quality amps for the install market are designed to be part of system where these concerns are taken into account.
    - Johnythree 10y ago
      Yes, if it does, it's because of crappy (eg cheap) design. Any amplifier designer should assume that the mains power is very, very noisy.
- timpattinson 10y ago
  Because some of these venues also run lighting rigs in the order of magnitude of 100KW and probably don't have the space/money/expertise to install a UPS with that power capacity.
  - TakerofVita 10y ago
    Would lights need to be run on the UPS, or just the audio equipment?
    - cdcarter 10y ago
      A single loudspeaker in a line array can draw up to 24A at 240V [0]. Even a very small rig of 6 speakers would require over 30kw. A 50kw UPS [1] can be purchases for a very affordable $25,000 in 2016 [2]. When building a performance art venue in 1960 or today, a technical ground is a much more suitable option than a UPS. [0]: http://www.meyersound.com/sites/default/files/leo-m_ds_a2.pdf http://www.meyersound.com/sites/default/files/leo-m_ds_a2.pd... [1]: http://powerquality.eaton.com/Products-services/Backup-Power-UPS/93PM.aspx?cx=3&cmx=231&GUID=9504FAC4-72FB-4F2A-8EA1-884DC98E48FA http://powerquality.eaton.com/Products-services/Backup-Power... [2]: https://store.fgcupssystems.com/products/eaton-93pm-50kw-480-480v-9pa05d0000a00r2-double-conversion-base-unit-ups?utm_medium=cpc&utm_source=googlepla&variant=3284689283&gclid=Cj0KEQjw0MW9BRDxtYTn2_S699MBEiQAw33y48QlEEM0drpwzwMRday9T7oUo7vXtQ7myXfVEsAb7ncaAshd8P8HAQ https://store.fgcupssystems.com/products/eaton-93pm-50kw-480...
timpattinson 10y ago
This is a valid concern - due to not only differing grounds but also the transients/hf noise created from ten- and hundred-KW lighting dimmer systems, audio and lighting power must be kept seperate
jcrawfordor 10y ago
In recording studios, you will sometimes find 'technical power' which is delivered on balanced wiring from an isolation transformer. This is rarely seen outside of radio and television studios, though. Many performing arts spaces have a simpler version, of dedicated outlets for power amplifiers that are on an isolation transformer if anything, but usually just a separate run to the main panel - this is mostly just to avoid the ground loop problem, as you mentioned, as well as to avoid certain kinds of noise that amplifiers might pick up. I doubt that the isolation gained from having one's own pole transformer is any better than what an isolation transformer gets you. You'd still be subject to any noise or trouble in the distribution-level wiring, and at the end of the day I think most of the problematic electrical issues you could have in audio are going to originate in your own house anyway. It's probably much better bang for your buck to put your audio equipment on a nearby isolation transformer, which are not necessarily cheap but certainly don't run in the five figures (or at least not until they get very large). But with these kinds of audiophiles, bang for your buck isn't what it's about. Having known some audiophile extremists like this, at least in my limited experience, it's just a status symbol. Edit: As an anecdote about amp noise, while lighting is a pretty big issue most permanent venues have their lighting well-segregated into a central dimmer rack anyway. The most notable time I got an angry noise out of an amplifier is when I accidentally plugged a hydraulic manlift into a poorly labelled amp rack socket. When I went to ascend, the noise from the house speakers made me just about jump out of my skin, to the great amusement of my coworkers.
- honkhonkpants 10y ago
  Rarely seen outside of studios and hospitals. I guess people will point and laugh at this but they probably aren't laughing at FDA device safety rules. "Technical power" in your house is pretty much against all building codes. You need color-coded outlets and warning signs on all outlets and on the entry doors, in a commercial setting where the code allows such wiring. On the other hand, wiring your amps up this way has a certain economy to it; it's actually pretty cheap and effectively solves the problem for a lot less than the $10k (plus ongoing monthly costs of extra power service) cited in this article. Edit: NEC here: http://www.equitech.com/support/647.html http://www.equitech.com/support/647.html
engi_nerd 10y ago
I have personally encountered difficulties in grounding and bonding when different portions of a distributed instrumentation system used "local" grounds on the nearest aircraft structural member as their ground reference. The ground potential from one place to another on the structure of an aircraft in flight can vary wildly. This caused no end of problems (sudden shifts in parameters, dead power supplies, etc). For performance critical applications, minimize the number of grounds.

DINKDINK 10y ago

Why not just use a UPS (Uninterruptible Power Supply)?

LeoPanthera 10y ago
Even a UPS is probably overkill. A Power Conditioner should be sufficient. https://en.wikipedia.org/wiki/Power_conditioner https://en.wikipedia.org/wiki/Power_conditioner
mirimir 10y ago
My thought, exactly. With a dual-conversion UPS, I don't believe that there'll be any noise from the power grid.
metaphor 10y ago
Audiophile Mistake #1: Proposing a sensible solution to a problem which doesn't exist.
- matwood 10y ago
  Like wooden vs. plastic volume knobs? :) http://bobbyowsinski.blogspot.com/2012/05/485-volume-knob.html http://bobbyowsinski.blogspot.com/2012/05/485-volume-knob.ht...
- LeoPanthera 10y ago
  It's not completely outlandish to imagine that noisy power could cause noise in the audio output of an amplifier. I would hope that any good quality amp would filter the incoming power, though.
  - superuser2 10y ago
    I'm guessing that good quality amps for the install market are designed to be part of system where these concerns are taken into account.
  - Johnythree 10y ago
    Yes, if it does, it's because of crappy (eg cheap) design. Any amplifier designer should assume that the mains power is very, very noisy.
timpattinson 10y ago
Because some of these venues also run lighting rigs in the order of magnitude of 100KW and probably don't have the space/money/expertise to install a UPS with that power capacity.
- TakerofVita 10y ago
  Would lights need to be run on the UPS, or just the audio equipment?
  - cdcarter 10y ago
    A single loudspeaker in a line array can draw up to 24A at 240V [0]. Even a very small rig of 6 speakers would require over 30kw. A 50kw UPS [1] can be purchases for a very affordable $25,000 in 2016 [2]. When building a performance art venue in 1960 or today, a technical ground is a much more suitable option than a UPS. [0]: http://www.meyersound.com/sites/default/files/leo-m_ds_a2.pdf http://www.meyersound.com/sites/default/files/leo-m_ds_a2.pd... [1]: http://powerquality.eaton.com/Products-services/Backup-Power-UPS/93PM.aspx?cx=3&cmx=231&GUID=9504FAC4-72FB-4F2A-8EA1-884DC98E48FA http://powerquality.eaton.com/Products-services/Backup-Power... [2]: https://store.fgcupssystems.com/products/eaton-93pm-50kw-480-480v-9pa05d0000a00r2-double-conversion-base-unit-ups?utm_medium=cpc&utm_source=googlepla&variant=3284689283&gclid=Cj0KEQjw0MW9BRDxtYTn2_S699MBEiQAw33y48QlEEM0drpwzwMRday9T7oUo7vXtQ7myXfVEsAb7ncaAshd8P8HAQ https://store.fgcupssystems.com/products/eaton-93pm-50kw-480...

timpattinson 10y ago

This is a valid concern - due to not only differing grounds but also the transients/hf noise created from ten- and hundred-KW lighting dimmer systems, audio and lighting power must be kept seperate

jcrawfordor 10y ago

In recording studios, you will sometimes find 'technical power' which is delivered on balanced wiring from an isolation transformer. This is rarely seen outside of radio and television studios, though. Many performing arts spaces have a simpler version, of dedicated outlets for power amplifiers that are on an isolation transformer if anything, but usually just a separate run to the main panel - this is mostly just to avoid the ground loop problem, as you mentioned, as well as to avoid certain kinds of noise that amplifiers might pick up. I doubt that the isolation gained from having one's own pole transformer is any better than what an isolation transformer gets you. You'd still be subject to any noise or trouble in the distribution-level wiring, and at the end of the day I think most of the problematic electrical issues you could have in audio are going to originate in your own house anyway. It's probably much better bang for your buck to put your audio equipment on a nearby isolation transformer, which are not necessarily cheap but certainly don't run in the five figures (or at least not until they get very large). But with these kinds of audiophiles, bang for your buck isn't what it's about. Having known some audiophile extremists like this, at least in my limited experience, it's just a status symbol. Edit: As an anecdote about amp noise, while lighting is a pretty big issue most permanent venues have their lighting well-segregated into a central dimmer rack anyway. The most notable time I got an angry noise out of an amplifier is when I accidentally plugged a hydraulic manlift into a poorly labelled amp rack socket. When I went to ascend, the noise from the house speakers made me just about jump out of my skin, to the great amusement of my coworkers.

honkhonkpants 10y ago
Rarely seen outside of studios and hospitals. I guess people will point and laugh at this but they probably aren't laughing at FDA device safety rules. "Technical power" in your house is pretty much against all building codes. You need color-coded outlets and warning signs on all outlets and on the entry doors, in a commercial setting where the code allows such wiring. On the other hand, wiring your amps up this way has a certain economy to it; it's actually pretty cheap and effectively solves the problem for a lot less than the $10k (plus ongoing monthly costs of extra power service) cited in this article. Edit: NEC here: http://www.equitech.com/support/647.html http://www.equitech.com/support/647.html

engi_nerd 10y ago

I have personally encountered difficulties in grounding and bonding when different portions of a distributed instrumentation system used "local" grounds on the nearest aircraft structural member as their ground reference. The ground potential from one place to another on the structure of an aircraft in flight can vary wildly. This caused no end of problems (sudden shifts in parameters, dead power supplies, etc). For performance critical applications, minimize the number of grounds.