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Which gear needs to be plugged into isolation transformer?

Hey ive been thinking about deliver clean power to my rig as it approaches completion. The use of isolation transformers seems to make sense since the rig will be in a regular house, without any modifications to the existing electric service. My questions are:

1. What pieces of gear need to be plugged into an isolation transformer?
  • Powered Studio Speakers?
  • Audio Interface/Converters?
  • The Computers?
  • Outboard pres, comps, eqs?
  • Guitar Amps?
  • Midi/DAW controllers (devices that don't pass audio)
  • USB devices like external drives?
  • Flatscreens?
  • Tape machines, record players?
  • Network switch for slave pc's?
  • Network switch for internet access?
  • Anything else?
2. Does all equipment need to be connected to a single iso xformer?

3. Do certain pieces need to be grouped to be plugged into the same xformer? ie, the monitors and converters.

4. Do the iso xformers need to be all on the same circuit or outlet in the house?

5. Are fridges, cfl light bulbs, air conditioners, other appliances a concern if on the same cricuit as the iso xformer

6. If isolation xformers are used, does an additional iso box need to be used specifically for the usb converters? (Bozwell had linked one in another thread recently that he got good results with a laptop.)

7. Do battery backups, rack power conditioners, rack voltage regulators, enhance, negate, make redundant, or have no effect, on the isolation xformers performance? ie is any of the other stuff useful or a waste or harmful.

8. Are rfi, wifi, cellphone, emi, terrestrial radio, Bluetooth, interferences a concern?

Im interested both in what's ideal, and what's the minimal requirements. I will probably wait to do critical analog to digital transfers either at the studio, or until my new place is ready with proper studio grade electrical and emi/rfi rejection.

The rig is 5 PCs, a laptop, 1 NAS, 2 converters, an eleven rack amp sim, a midi controller, 2-3 pairs of speakers (for main and capture systems) probably a tablet for remote control, and maybe a couple outboard units. 1 pc will occasionally be connected to the internet, the nas, and laptop constantly connected. Not sure if it will be by cat6 or wifi. I also anticipate sending BT audio to bt speakers around the house via either built in BT, or a little transmitter connected to the interface, maybe both.

Usage of system would be generally just midi composing, audio demos, and mixing for fun. Possibly some podcasts and videos, and maybe safety copies of archive stuff like tapes, vhs, vinyl. I can't imagine much paid gigs in this place, but perhaps some small editing, or mixing. Also general web browsing and streaming.

Thanks.

Comments

Boswell Fri, 12/06/2019 - 23:16
In simple terms, you either need everything plugged into the output of the iso transformer or nothing. Most audio gear carries a mains earth through its input and output cabling, so if you have a mixture of interconnected things through the transformer and not through the transformer, the output ground would be connected to the input ground, negating tha isolation.

It's worth considering a quality mains filter to reduce the effects of fridge clicks and other mains-borne interference, and even a UPS of the type that regenerates the mains sinewave. These are not cheap, but they can make quite a difference. They can act as isolation transformers as well.

paulears Sat, 12/07/2019 - 03:59
I've always looked on them as problem solvers - used to solve a specific issue.

There are a number of issues when it comes to using them in an installation. Size and cost are pretty important. High current ones can be amazingly expensive. They also have quite a lot of myths. They provide isolation - that's all. They do NOT cure waveform distortion. Most will happily pass spikes and superimposed noise unless designed with filters to remove harmonic distortion. They're good at reducing current flow in the grounds as there is no direct path. Some of your kit will already have them if they use class II operation where the power supply transformer does the same thing. Your switch mode interference causers will still do it , because they are downstream of the transformer, and if they're noisy will still contaminate everything.

That all said, my house is 1964, with a mix of modern and original wiring, and I don't have any switch based interference in my studio that is on it's own ring circuit. In modern locations, I suspect clicks and pops are actually indications there are problems elsewhere that could be fixed. Using transformers to 'fix' the problem just leaves the real one untouched. You also need to check on the circuit protection. Using transformers can impact on how RCD devices work in some cases. Regenerative UPS driving a faulty device may well remove the protection in some circumstances as they are in a sense, a totally separate supply.

kmetal Sun, 12/08/2019 - 18:39
Boswell, post: 462849, member: 29034 wrote: It's worth considering a quality mains filter to reduce the effects of fridge clicks and other mains-borne interference, and even a UPS of the type that regenerates the mains sinewave. These are not cheap, but they can make quite a difference. They can act as isolation transformers as well.

By a mains filter, are you referring to the isolation xformers that connect to the main breaker box?

Also im still unsure of this- if i use several of the iso xformers that plug into a standard outlet, is this acceptable? Or do the equipment have to be plugged into the same iso xformer, requiring a much higher wattage/amperage unit.

Do midi cables carry the earth ground like usb and audio does?

And the iso xformer does nothing for emi, rfi, airborne interferences?

paulears, post: 462854, member: 47782 wrote: That all said, my house is 1964, with a mix of modern and original wiring, and I don't have any switch based interference in my studio that is on it's own ring circuit. In modern locations, I suspect clicks and pops are actually indications there are problems elsewhere that could be fixed. Using transformers to 'fix' the problem just leaves the real one untouched.

My current place is from 1976. Did you use an isolated ground method on your studios circuit?

I agree problems should be solved at the root. Im just not willing to put any work into the existing house since its a rental, and im planning on moving within the next year or two to a place i own. I just wont see a return on investment in that short of time.

Worse comes to worse ill just live with any issues at this place, which may delay critical archiving projects.

cyrano Sun, 12/08/2019 - 18:55
Boswell, post: 462849, member: 29034 wrote: In simple terms, you either need everything plugged into the output of the iso transformer or nothing.

This is the most important part.

And "everything" usually means it's too expensive, unless you have a specific problem too solve. In that case you should try-before-you-buy.

kmetal Sun, 12/08/2019 - 19:30
cyrano, post: 462862, member: 51139 wrote: This is the most important part.

And "everything" usually means it's too expensive, unless you have a specific problem too solve. In that case you should try-before-you-buy.

Again, i ask does it have to be the same iso xformer, or can it be several separate xformers?

dvdhawk Mon, 12/09/2019 - 01:09

How many watts (0r amperes) does your gear list add up to ? Add them up. Computers, displays, drives, routers, interface, 11R, monitor speakers, other processors, all of the sensitive gear.

US line voltage being 120v, the 1000 watt IS1000 has a theoretical max of 8.33 amps. It might be overly cautious, but I'd be inclined to avoid going right to the 1000w threshold and leave 10% headroom. (900w / 7.5amp total)


Ideally, you'll have one central source of power and one path to ground for all of your interconnected gear. Unless you've got a major problem somewhere, a decent AC line conditioner - the kind without a dedicated iso transformer (ETA, Furman, Tripp-Lite) will usually be all you need for most residential electrical distribution. UPS on your critical computer components is a no-brainer. If for no other reason so you don't lose anything if/when the power flickers.

If I already had a great sounding control room and wanted to go the extra mile, I'd look into a balanced power unit instead. It uses Common Mode Rejection to remove noise from the electrical supply in the same way a balanced cable cancels out noise. I swapped my 20-amp Furman balanced power supply to Chris (Audiokid) a while back, and will replace it when I get to the point I have a suitable place to use it. At the time audiokid was set up for very critical listening and said he could hear a drop in his noise floor when he put in the Furman. That was with high-end gear to begin with. Maybe he'll chime in with his final assessment of how effective it was overall.
 

kmetal, post: 462860, member: 37533 wrote: ... the iso xformer does nothing for emi, rfi, airborne interferences?

In addition to breaking the physically connection, isolation transformers will eliminate EMI/RFI noise and should be equipped to handle surges and spikes too.

Try to stay away from circuits with the other usual residential noise makers (furnace, AC, fridge, oven, pump - anything with a big motor, fan, or heating element that cuts in and out really).

Isolation transformers can be useful. If I'm putting a system in new building for work and budget permits, the electricians will put in one big transformer to isolate an entire A/V sub-panel. That dedicated panel will power everything A/V related and keep us separated from the institutional sized kitchen appliances, HVAC, and everything else. By the time you connect an audio console, plus a computer system that is used as a sound and video source at FOH, plus an amp rack somewhere backstage, plus a variety of electrified instruments and amps on stage, plus one or more projectors in the rafters, - that's a lot of potential for noise if they're not all coming from the same sub-panel with the same path to ground. They are all tied together by virtue of their hardwired shields.
Even though a lot of these new building projects are big 3-phase systems with a lot of potential for polluted power, a iso transformer is usually not a budget priority and we just do without one. In the A/V guy's perfect world, he'd have one leg of the 3-phase just for his equipment and put the rest of the building on the other 2 legs. However, electricians (rightly) want to distribute the building's load evenly over the 3 legs. For a new building (with or without an iso transformer) I'd specify a single electrical sub-panel dedicated to all the A/V gear, (FOH, backstage, on stage, and overhead receptacles), which is 99% of the battle. I also always use Furman and ETA power conditioning and sequencing at FOH and in any outlying racks, plus small conditioners at the projector locations. When I'm putting a system in an older building (which is way more often than new buildings from the ground up), we do without iso transformers and almost never have a dedicated sub-panel for A/V gear. Even then, I rarely have problems that can't be solved with the ground lift switch on a DI box. The only time I can recall a noise gremlin that had me pulling my hair out, it turned out to be a faulty, (brand new) soundboard.

It doesn't make a lot of sense to me to use multiple iso transformers. If the gear is centralized, I think it would be less expensive to buy one big iso unit rather than two small units. If it's gear scattered all over the house, I'd use the iso in your primary DAW location and regular line conditioners everywhere else. Multiple power conditioners seems perfectly reasonable to me. I have one, or more two, in every rack I own.

MIDI cables usually do ground to the chassis of the gear they connect together, but if you've done everything else right (a single power source with one path to ground) it shouldn't be an issue. I wouldn't bother filtering the wireless bluetooth stuff that is never physically interconnected by wire.

And somewhat ironically, the kind of big isolation transformer that someone might use to remove noise and hum from their sound equipment will often generate a mechanical hum of its own.


RELEVANT READING MATERIAL
https://www.apc.com…

https://download.sc…

http://www.datcomin…

paulears Mon, 12/09/2019 - 01:24
Separated technical earths (grounds) are quite rare now in the UK. The BBC used them as standard but now grounding arrangements tend to be done to our version of 'code' so our standard system is with a single earth, usually at the point of entry of the cable where neutral and ground are joined together - this ground reference is then distributed to all outlets in use. We have a slightly different system for separate outbuildings, where they usually have their own bonding to ground that prevents extending the first buildings ground to cover the new extension to the perimeter of the common ground potential. My studio is within the existing property boundary so uses the distributed earth, but for me this is actually very close - the studio being right next to the electrical intake - so my ground is only ten feet or so from the one that services the entire building. Single phase of course. 3 phase is very rare in any domestic property here. Our typical intakes for domestic property are 60-100A, single phase 230V (although it's actually 240V, but in the European Union we are 'harmonised', so we call 240V, 230V and our euro neighbours on 220V also call theirs 230V so we are all happy. )

kmetal Mon, 12/09/2019 - 10:23
dvdhawk, post: 462866, member: 36047 wrote: How many watts (0r amperes) does your gear list add up to ? Add them up. Computers, displays, drives, routers, interface, 11R, monitor speakers, other processors, all of the sensitive gear.

US line voltage being 120v, the 1000 watt IS1000 has a theoretical max of 8.33 amps. It might be overly cautious, but I'd be inclined to avoid going right to the 1000w threshold and leave 10% headroom. (900w / 7.5amp total)


Ideally, you'll have one central source of power and one path to ground for all of your interconnected gear. Unless you've got a major problem somewhere, a decent AC line conditioner - the kind without a dedicated iso transformer (ETA, Furman, Tripp-Lite) will usually be all you need for most residential electrical distribution. UPS on your critical computer components is a no-brainer. If for no other reason so you don't lose anything if/when the power flickers.

If I already had a great sounding control room and wanted to go the extra mile, I'd look into a balanced power unit instead. It uses Common Mode Rejection to remove noise from the electrical supply in the same way a balanced cable cancels out noise. I swapped my 20-amp Furman balanced power supply to Chris (Audiokid) a while back, and will replace it when I get to the point I have a suitable place to use it. At the time audiokid was set up for very critical listening and said he could hear a drop in his noise floor when he put in the Furman. That was with high-end gear to begin with. Maybe he'll chime in with his final assessment of how effective it was overall.


In addition to breaking the physically connection, isolation transformers will eliminate EMI/RFI noise and should be equipped to handle surges and spikes too.

Try to stay away from circuits with the other usual residential noise makers (furnace, AC, fridge, oven, pump - anything with a big motor, fan, or heating element that cuts in and out really).

Isolation transformers can be useful. If I'm putting a system in new building for work and budget permits, the electricians will put in one big transformer to isolate an entire A/V sub-panel. That dedicated panel will power everything A/V related and keep us separated from the institutional sized kitchen appliances, HVAC, and everything else. By the time you connect an audio console, plus a computer system that is used as a sound and video source at FOH, plus an amp rack somewhere backstage, plus a variety of electrified instruments and amps on stage, plus one or more projectors in the rafters, - that's a lot of potential for noise if they're not all coming from the same sub-panel with the same path to ground. They are all tied together by virtue of their hardwired shields.
Even though a lot of these new building projects are big 3-phase systems with a lot of potential for polluted power, a iso transformer is usually not a budget priority and we just do without one. In the A/V guy's perfect world, he'd have one leg of the 3-phase just for his equipment and put the rest of the building on the other 2 legs. However, electricians (rightly) want to distribute the building's load evenly over the 3 legs. For a new building (with or without an iso transformer) I'd specify a single electrical sub-panel dedicated to all the A/V gear, (FOH, backstage, on stage, and overhead receptacles), which is 99% of the battle. I also always use Furman and ETA power conditioning and sequencing at FOH and in any outlying racks, plus small conditioners at the projector locations. When I'm putting a system in an older building (which is way more often than new buildings from the ground up), we do without iso transformers and almost never have a dedicated sub-panel for A/V gear. Even then, I rarely have problems that can't be solved with the ground lift switch on a DI box. The only time I can recall a noise gremlin that had me pulling my hair out, it turned out to be a faulty, (brand new) soundboard.

It doesn't make a lot of sense to me to use multiple iso transformers. If the gear is centralized, I think it would be less expensive to buy one big iso unit rather than two small units. If it's gear scattered all over the house, I'd use the iso in your primary DAW location and regular line conditioners everywhere else. Multiple power conditioners seems perfectly reasonable to me. I have one, or more two, in every rack I own.

MIDI cables usually do ground to the chassis of the gear they connect together, but if you've done everything else right (a single power source with one path to ground) it shouldn't be an issue. I wouldn't bother filtering the wireless bluetooth stuff that is never physically interconnected by wire.

And somewhat ironically, the kind of big isolation transformer that someone might use to remove noise and hum from their sound equipment will often generate a mechanical hum of its own.


RELEVANT READING MATERIAL
https://www.apc.com…

https://download.sc…

http://www.datcomin… Transformer-free.pdf


Thank you sir. I will make a spreadsheet of the wattage/amperage as you and boulder suggested, even tho its largely just academic at this point. Off the top of my head im looking at over 3000w worth of computer psu's with 800-1500w of actual draw. (I over spec'd for psu efficiency)

I thank everyone alot for helping on this topic! Based on what ive been told i think ive found a reasonable approach.

To start:
Power conditioners everywhere. No iso xformers for the machine room/slave rack/ secondary gear. For the main daw, iso xformer if needed.

For the new place, ill spec the typical balanced load for each panel, and isolated ground (star grounding) for the studio sub panel, and good moderate price power conditioners for everything.

A backup power system will be spec'd for the entire house, likely consisting of an emergency generator, and a battery backup/powerwall tied into my solar/wind power system.

Ill have to learn how to verify the quality/purity of my power, and then take further action if needed.

My experience with a leaky power xformer on the at the wave cave was horrifying until one day they replaced it and viola' noise not an issue! At Normandy, such great care was taken back when they built it, it was a dream. That was my aha! moment about how clean power sounds more solid, and has more of that elusive "thing" that's on good recordings. Its more than just lack of hums, everything sounds more "there".

Anyway thanks again everyone for your thoughtful replies and time. Next step is to learn how to check the quality of my power, and try to actually understand power better than just what i parrot from books.

Cheers!!!

paulears Mon, 12/09/2019 - 10:41
You'll be surprised how little power studio kit really consumers. My computer has a 300W PSU, and it takes no more than 160W even when running UsB powered devices. Power amps are very good examples - not the Class D one, but good old heavy transformer PSU versions. I've a PA rack with amp values that add up to 8500W. turning the entire rack on by the wall socket trips the 16A MCB with the surge current, but since running, with loud red lights everywhere too loud music driven g it hard, the total current is below 10A. Our three phase power is meant to run as balanced as possible in venues this is rarely possible, and I'm just not convinced that power conditioners and other interesting devices are actually needed. A friend exulted the improved quality running with his UPS gave the mixer and audio system components. Then he discovered that it was not a regenerating type, and his kit was running off plain mains power, with the UPS kicking in if it failed.

kmetal Mon, 12/09/2019 - 13:29
paulears, post: 462873, member: 47782 wrote: My computer has a 300W PSU, and it takes no more than 160W

Right, this is common because computer psu's run most efficiently at 40-60% load. Many off the shelf computers won't leave adequate headroom, which often results in a more noisy fan, and earlier component failure

This trend my die off since modern power supplies are much more linear in their efficiency curve. However many units have fans that wont kick in until 25% or so draw, so it can be advantageous for people who need a silent computer.

A common 15A breaker is designed to deliver 12A.

One thing i very much appreciate about QSC amps is they're reccomend breaker size for each model amplifier. They also include wattage draw ratings at 1/3, 1/2, and full power.

paulears, post: 462873, member: 47782 wrote: I'm just not convinced that power conditioners and other interesting devices are actually needed.

Ive not had great results with them as hum removers, but my monster power conditioner did shut my stuff down when a place was supplying too much voltage. I can't say ive ever heard a difference, even with $2k voltage regulators.

That said, i like having the front mounted power switch, and rear plugs for the gear.

I understand confirmation bias is a real thing.

dvdhawk Tue, 12/10/2019 - 10:36
Even the best power conditioners are not going to be a panacea to cure every electrical problem. They do what they were designed to do reasonably well.
A moderate priced model is usually all I would recommend, unless we need power sequencing for an installation.

They will not eliminate a ground loop. That's a separate issue with known cures.
They will not keep a piece of equipment with a poorly designed power-supply or poor shielding from making the noise it generates internally.
They will not help in the event of a brown-out. (You need a voltage-regulating line conditioner for that.)

They will protect you from spikes, surges, and over voltage that originates from outside your system.
They will remove the majority of noise on the AC sine wave that originates from outside your system.
They are a much better way to distribute power than plastic, dollar store cheapo power strips.

I'm sure all of your audio gear is up to a reasonably high standard. Typically, electrical noise comes from other things (refrigerators, furnace fans, light fixtures) outside of your audio system. I've been told that electric providers often use the 60Hz sine wave (US) as a carrier for a tone(s) that lets them monitor their system for outages and other problems.

kmetal Tue, 12/10/2019 - 14:09
Do you know if the economy model furman conditioners reasonable performance for the dollar? I believe they are the "merit series". Its what i had in mind for this rough and tumble setup.

dvdhawk, post: 462880, member: 36047 wrote: They will protect you from spikes, surges, and over voltage that originates from outside your system.

Good to know my old one was doing its job!

dvdhawk, post: 462880, member: 36047 wrote: They will remove the majority of noise on the AC sine wave that originates from outside your system.

This is cool. Would this be audible? Or it it one of those things that's super subtle or becomes noticeable after the (noise) is stacked up on many tracks, or shows up suddenly when the track gets super compressed? Is it one of those things that just shows up on a scope? Either way less noise is a good thing imho.

cyrano Wed, 12/11/2019 - 16:44
You need to test if it's a solution to your problem. Transformers are very different. The kind of noise they stop is different too.

And if you start including DC to AC converters it's an entirely different thing. Chances are a UPS will add noise in stead of eliminating it.

But, again, every setup is different. And if you haven't got a problem, it's a waste of time and money.

kmetal Wed, 12/11/2019 - 18:08
cyrano, post: 462891, member: 51139 wrote: You need to test if it's a solution to your problem. Transformers are very different. The kind of noise they stop is different too.

And if you start including DC to AC converters it's an entirely different thing. Chances are a UPS will add noise in stead of eliminating it.

But, again, every setup is different. And if you haven't got a problem, it's a waste of time and money.

I certainly don't want to treat problems that dont exist!! My biggesr concern is the air conditioner and mini fridge, which are likely to be in the same room. I could run an extension cable to a different room/circuit but id prefer not to have to.

Do you think i should test by just setting up the gear, or is there something i can do ahead of time?

I will likely be moving the main daw into a different room or two as this place gets renovated. I also anticipate having the slave pcs in a seperate room or closet.

dvdhawk Wed, 12/11/2019 - 23:57
Pros and cons to everything, Kyle.

The Furman Classic series offers higher levels of noise filtering, and surge protection than the Merit series, but if you plan to plug the Merit into another conditioner or iso transformer upstream then it doesn't really matter.

The Furman Classics provide protection from sustained over-voltage condtions, and also use surge protection that is "non-sacrificial, meaning it doesn't slowly get destroyed doing its job. The Merit series does not list either of those more advanced features, so I assume they just work like any other normal surge protector. Normal surge protectors use simple MOV (metal oxide varistors) on the Line to absorb the spikes. MOVs are cheap and they're effective for basic surge suppression, but every hit they take slowly chips away at their integrity - until eventually they burn out. Also as far as I know, Furman (like most manufacturers) only protects the Line and ignores the Neutral and Ground.




The ETA PD8 models have always been my personal choice for bang-for-your-buck power conditioners. The older ETA versions I've used also apply filtering and surge protection to the Neutral, and the Ground (in addition to the Line). Now, there's a newer version of the ETA (PD8A and PD8LA) that I haven't used yet. I don't know for sure if all the primary features have carried forward to the newest models.

You're going to need a whopper of a UPS unit for 1500-3000watts of computers + everything else and a 30A (or more) circuit to power it.

[[url=http://[/URL]="https://www.power-s…"]How Do I Properly Size My UPS[/]="https://www.power-s…"]How Do I Properly Size My UPS[/]

paulears Thu, 12/12/2019 - 02:29
I think before I did anything, I'd get the gear running. Let's look at the equipment. Air-con and a fridge is really just a motor - the compressor, and perhaps the switch contacts that turn the thing on and off as required. In this day and age, suppressing these transients is not exactly hard for a decent manufacturer to implement. The noise source would be the hard edge of the waveform cutting in part way through the cycle, and on a power system with sufficient diversity, this is very unlikely to have detrimental effects on other equipment. In the UK ring power circuits are the norm, so we'd have perhaps dozens, maybe now with wall wart type power supplies, maybe 30+ (using my house as an example) so noise sources are plentiful. With new AC and the fridge, clicks, pops or noise really should have been designed out. I'd 100% not be spending money until a problem surfaces - and I think on a new build with new electrics it's very unlikely.

kmetal Thu, 12/12/2019 - 20:20
dvdhawk, post: 462895, member: 36047 wrote: The ETA PD8 models have always been my personal choice for bang-for-your-buck power conditioners. The older ETA versions I've used also apply filtering and surge protection to the Neutral, and the Ground (in addition to the Line). Now, there's a newer version of the ETA (PD8A and PD8LA) that I haven't used yet. I don't know for sure if all the primary features have carried forward to the newest models.

Great info about the different furman units. Ive only used classic series, and monster brand units in the past.

Im definitely gonna take a look at eta, ive never heard if them before. Before i buy anything from them ill verify if those important features from previous models have been carried over.

dvdhawk, post: 462895, member: 36047 wrote: You're going to need a whopper of a UPS unit for 1500-3000watts of computers + everything else and a 30A (or more) circu

Yeah im not loving the ups costs ive seen in that wattage range. Its one downside to the master/slave config. Id likely only connect the master computer and interface, along with a screen to a ups, to keep wattage requirements to a minimum. the master is the only computer i save stuff to.

I will probably not get a ups for this place, since i am hoping to have a nice backup system in the new place based around a generator, and tesla powerwall. Hopefully this will let me dodge individual ups units.

Keeping the slaves and nas and utilitarian pcs in another room, in a server rack, should keep me within the range of the 15a circuits that the rooms in this house have. If i really have to ill run extension cords.

I would like to test the power consumption since this system is really more of a prototype than anything, to see how i like using slave pcs, and see how well i can get remote/online mixing and/or tracking.

Based on the results ill spec out the 'real' system for the new place using better computer and audio components.

paulears, post: 462896, member: 47782 wrote: I think before I did anything, I'd get the gear running. Let's look at the equipment. Air-con and a fridge is really just a motor - the compressor, and perhaps the switch contacts that turn the thing on and off as required. In this day and age, suppressing these transients is not exactly hard for a decent manufacturer to implement. The noise source would be the hard edge of the waveform cutting in part way through the cycle, and on a power system with sufficient diversity, this is very unlikely to have detrimental effects on other equipment. In the UK ring power circuits are the norm, so we'd have perhaps dozens, maybe now with wall wart type power supplies, maybe 30+ (using my house as an example) so noise sources are plentiful. With new AC and the fridge, clicks, pops or noise really should have been designed out. I'd 100% not be spending money until a problem surfaces - and I think on a new build with new electrics it's very unlikely.

The ac and mini fridge at one studio i built didn't add any interference, although they were on their own 'dirty power' circuit. The audio circuits were seperate, but did not have an isolated ground.

In my cousin's home studio however, pops and noise became an issue a few years after i built it, when they installed a multi split ac/heat system in the house, and control room. This was in 2014, and it was a high end ac unit. Despite being on its own circuit the audio gear picked up noise. They didn't have an isolated ground.

audiokid Fri, 12/13/2019 - 12:51
dvdhawk, post: 462866, member: 36047 wrote: If I already had a great sounding control room and wanted to go the extra mile, I'd look into a balanced power unit instead. It uses Common Mode Rejection to remove noise from the electrical supply in the same way a balanced cable cancels out noise. I swapped my 20-amp Furman balanced power supply to Chris (Audiokid) a while back, and will replace it when I get to the point I have a suitable place to use it. At the time audiokid was set up for very critical listening and said he could hear a drop in his noise floor when he put in the Furman. That was with high-end gear to begin with. Maybe he'll chime in with his final assessment of how effective it was overall.
Yes indeed, Dave, good memory! Thanks again for this wonderful product that I still have.
After installing it my converters were noticeably quieter. To my understanding, stable power keeps the voltage of a product operating at its best (guessing (bias etc). I noticed less noise between each ADDA path which translated to a quieter and smoother sound which gave my tracking and mix a more open, full sound. I would compare the more "open sound" I describe this to how fat and smooth instruments sound when they are all in tune together.

Boswell may explain stable power much better than I here.

dvdhawk Fri, 12/13/2019 - 16:40
Balanced Power Explained

AC Noise Demonstration Video

In addition to using rackmount Furman and ETA on audio installations, I often use small (2 receptacle) WattBox conditioners for ceiling mounted projector installations.

ETA used to make stage lighting dimmers and controllers that were popular with bar bands - before your time I'm sure. Just like Furman used to be known for crossovers and EQs before they got into power conditioning.

A very interesting read about the History of Furman Sound (and Power) - if you like rock history.

kmetal Fri, 12/13/2019 - 17:09
Gonna check out those links. I say thanks on behalf of myself and anyone else who enjoys them.

dvdhawk, post: 462911, member: 36047 wrote: I often use small (2 receptacle) WattBox conditioners for ceiling mounted projector installations.

Good call! I actually have been strongly considering 3 projectors, (front and sides) instead if flat screens cuz they are large and acoustically transparent.

dvdhawk, post: 462911, member: 36047 wrote: before your time I'm sure.

Yeah being born in 1984 has left me with nearly 150 years of recorded music/technology to catch up on.

dvdhawk Sat, 12/14/2019 - 10:39
kmetal, post: 462912, member: 37533 wrote: I actually have been strongly considering 3 projectors, (front and sides) instead if flat screens cuz they are large and acoustically transparent.

That's a fine idea, but you know the projectors all make audibile noise, right? Do you have a plan to mitigate the noise? In a conference room, classroom, bar room, church - no big deal, a certain amount of background noise is normal. In a critical listening environment the cumulative noise of 3 quiet-ish projectors might wear on your nerves.
I'm not saying it's a deal-breaker, but I'd give it some thought. The difference in long-term cost of ownership would be significantly higher for projectors. (accounting for replacement lamps, electricity consumed, and during warm months the burden on your HVAC to offset the heat generated)

Projector Central is an invaluable resource for info on virtually every projector ever made. Their interactive "Projection Calculator", will do all the math for you regarding - what size the image will be from a given distance, with a specified lens. That's really handy, but also relevant here, their specs for each projector include an "Audible Noise" specification. Some manufacturers don't volunteer that noise spec, but you can often find in on their linked "Product Sheets". If they don't list it, that's probably a red flag as far as you're concerned. **NOTE: They do NOT say how that dB measurement was derived - so it's a spec that's ripe for misleading customers.

kmetal Sat, 12/14/2019 - 17:54
That's interesting. I never noticed the hum on my buddies projector, but i wasn't listening for it either. I could just use a single projector, or figure out a way to build an iso box.

If things go as i hope, the room will be 24x30x10 with large main speakers. So maybe the noise wont be an issue if i place the projector at the rear.

This room is supposed to resemble a post production, movie mix room, or theater, as opposed to a standard control room.

Ill just go with watever makes most sense as far as noise and cost of ownership. I appreciate the info!!!!

kmetal Sun, 12/15/2019 - 13:24
cyrano, post: 462928, member: 51139 wrote: Good luck at building a sound isolation box for a projector.

Projectors get awfully hot...

I plan on air conditioning the server closet and the tube amps, for consistent performance so i could may be just tap off that, it really depends on where its mounted. I could also just ventilate it up to the attic, or mount it like a thru wall ac unit.

Any insight on how warm they get?

kmetal Sun, 12/15/2019 - 13:55
paulears, post: 462930, member: 47782 wrote: My large Sanyo has a fan that kicks in when it gets too hot, and you don't want to have your hand in the exhaust for long. The discharge lamps get extremely hot and I'd hate too think how an enclosure would work without ducted exhaust and fresh air inlet.

The enclosure would definitely need to be ventilated or conditioned.

The good part is the projector isn't kicking out high db's at low frequencies. Even a basic insulated 2x4 frame with a single drywall sheet is around 35 db's of isolation at 1k.

The rear wall ceiling/wall junction will have a 2' tall x 4' deep bass trap, at least in the current plan (which could change drastically). Since the main blower of the multi split ac/heat is centered, mounted on the trap, and the hrv air exchanger is right above or below it, thats a perfect place for the projector, if it can throw 30feet. There's plenty of room for iso boxes, duct baffles, and ducting within the bass trap.

Any idea how loud your Sanyo gets, even crudely?

If my design is good enough and it makes sense, ill be able to vent the heat into an exchange chamber, and feed it back into the room(s) in the winter time.

My energy consumption will be high due to the ac and 4+ kw of lighting in another room im using for something else.

I can always just ventilated the machine closet instead of cool it.

paulears Mon, 12/16/2019 - 01:30
When I had the projector in the studio for a project, the noise the fan made was the about same as my rack mount audio computer - that uses one of those 80mm fans to vent the box - which is loud enough to be heard by a mic 6ft away - so not annoying in person, but loud enough to get recorded! I don't have any kind of dB figure for it though. Your single skin box would handle that kind of noise easily.
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