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[pounce]

it was recommended to me on another website that i consider getting an extreme isolation transformer for the electricity coming in to my studio. i do already have ups's for the computers and the furman pl pro conditioner/sequencer for the power. and everything is on it's own circuit. however, i've be willing to do anything that would help. iso transformers are cheap and readily available. so is it a good idea in general to have one. and if so, how do i determine if it's right for my room. my room is a little personal recording space run on it's own 20 amp circuit, so i suppose it's modest power needs. is this something everyone should be doing with their power? i don't have the cash to get a balanced power setup right now, so this might be a cool way to optimize the setup for less moola.

[trexrox]

well... there's one way to isolate the power for your studio... start at the source. the transformer from the pole.  It should feed two 110 lines into your place, one of which you can dedicate to audio only.  doing this with a liscensed electrician can be costly, though.  We had this done here and the power company put a brand new transformer on the pole, closer to the building to boot... made a noticable difference.

[pounce]

this is a great answer i would use if this were a commercial recording space. i just need to assure that i have clean power at home, and some  folks at the recordingconsole.net site mentioned how cheaply iso transformers could be had on ebay and whatnot, so it made me think it might be a good move in general.

[j.hall]

i bought a 5kva trannie for my mix room.

i've got about 30 amps of isolated "clean" power.  keep in mind that it's not 100% clean as you are merely branching off your existing panel.

i drove in a new ground rod, and built up a really nice grounding scheme for the studio.  

everything is working out nicely.

i got the trannie off ebay for about 450, another 50 for shipping.

the thing weighs 100 pounds.  so before you go overboard in thinking you need 60 amps of juice, you better evaluate moving these things around, and where you are going to put it.

the bigger the trannie the bigger the HUUUUUUMMMMMMMMMM.

mine barely hums at all, and it's back in my machine room so can't hear it anyway.

i fed my trannie with 220, then broke out 2 110 lines inside a sub panel.

i have four 20amp circuits for the mix room.

my basement renovation thread within my forum has a lot more detail about this.

[pounce]

so i'll put the question out this directly. if i can only afford one of the following, which would be most advisable for clean power in a personal project studio...

isolation transformer

balanced power supply


i can go the iso transformer route more cheaply, but i suspect that balanced power might even further reduce the noise floor and keep things in optimal shape. i don't think a person would typically do both. it's not that the power coming in is terrible, but it likely can be improved. so am i correct in thinking i should pick one of those routes and go with it. and if so, is the more expensive balanced power route worth the expense? lots of folks seem to think it's a great help for them. i'd like to see my gear perform at it's best. i want to start with cleaner power

[Sahib]

pounce wrote on Tue, 02 November 2004 18:56

so i'll put the question out this directly. if i can only afford one of the following, which would be most advisable for clean power in a personal project studio... isolation transformer balanced power supply

Balanced power supply as it also provides complete isolation from the mains.

However, you have to be very very careful with balanced power supply in terms of wiring and grounding of your studio.

Cemal

[pounce]

Sahib wrote on Thu, 04 November 2004 14:13

pounce wrote on Tue, 02 November 2004 18:56 so i'll put the question out this directly. if i can only afford one of the following, which would be most advisable for clean power in a personal project studio... isolation transformer balanced power supply Balanced power supply as it also provides complete isolation from the mains. However, you have to be very very careful with balanced power supply in terms of wiring and grounding of your studio. Cemal

i'm sure you are right. i would have one of my electrician friends help do the install. it looks like balanced power and a star ground system are a good idea. even for my modest personal project space. but what do you think i should bear in mind for this transition? what concerns should i have? i'd appreciate any info.

[John Klett]

thoughts and comments - there are other topics in this forum that cover a lot of this by the way...


Isolation of technical power from the rest of the power distribution in any given studio or facility does not require balanced power.  I used to be a balanced power fan and it does work in controlled settings but it is not an all encompassing solution to all your power quality and power distribution problems.

Power and Ground Isolation in its most basic form simply requires a mains transformer with two isolated windings.  The incoming line uses the primary and the isolated output uses the secondary.  The secondary can have a center tap and be connected to provide "balanced" power but this is not a requirement for isolation.

I have specified a number of completely balanced power distributions and have never succeeded in getting through an entire install without one problem or another cropping up.  After assuring the system really is isolated and doing everything right as would be required in any clean power system, the gear itself can be problematic.  Some equipment just does not LIKE balanced power.  I use a number of Crown Studio Reference amplifiers and they won't power up on balanced power.  Many vintage guitar amplifiers and keyboards are not happy on balanced power.  Many pieces of gear can be modified, others can't.  In studios where engineers haul in four of five racks of their own gear you have little control over how well that will turn out.  It's a pain in the ass.

I think the last fully balanced 60/0/60 power system I specified was done in 1998.  After that there were some hybrids and then I just went back to doing high quality distributions that come off of a very good isolation transformer - sometimes with a large UPS in front of it.  My preferred power distribution is single phase.  Single Phase (in the US) is 240 VAC with a centertap neutral that gives you two 120VAC "legs" or busses and is the standard form of electrical service as delivered to houses and residences outside of urban areas and industrial parks.  In other words - in the suburbs your typical house is getting 120/0/120 balanced power...  your DRYER, Electric Range and Air-Conditioners could very well be running on balanced power if you are not on polyphase (3 phase 208Y in the US).

In a single phase 240 VAC distribution I specify that heavy and fixed gear like consoles, large tape machines and racks for of ProTools and CPU's run on 240VAC single phase - balanced.  For rack gear and other items that can't run on anything but 120 or can't deal with balanced power we have standard 120VAC grounded neutral right out of the same distribution panel.

Typically I am doing systems 10KVA to 25KVA in single phase and systems up to 225KVA in polyphase.  The isolation transformers I specify are high K factor high efficiency types.  A small home studio may require something like a 5KVA isolation transformer (four circuits each drawing 8 Amps at 120VAC would be bumping up against the full (80% de-rated) capacity of a 5KVA transformer.  That's quite a bit of power.  You can run a Trident Series 80, an M79 or MM1200 24 track, a 24i/o HD system, a moderate amount of rack gear and a pair of self powered near-field speakers off that.  I'd rather see a larger transformer but 5KVA could do all that.

How much do these cost?  I have not priced anything smaller than 10KVA lately but I do have some recent figures for 10KVA and 15KVA at hand.  BEFORE SHIPPING a single phase 10KVA K-13 isolation transformer, of the type that I specify, with an additional electrolytic shield and in a proper NEMA enclosure would cost about $2200 and weigh 380 pounds.  The 15KVA version would be about $2600 and weight 415 pounds.

Grounding - Ground Stakes and so on have been covered in other topics in this forum but - one thing...  You have to confirm that your new isolated power and ground system is really isolated once you have all your gear connected.  The easiest way to do that is by de-energizing your entire system (removing power from the isolation transformer primary), lifting your isolated ground and measuring continuity from your isolated ground bar and the mechanical service ground.  You should see no continuity until you reconnect the isolated ground bar to the big fat IG ground wire.  Note... you have to use distribution panels with an isolated neutral bus.  Many panels are sold with neutral bonded to the box as would be the case for a load center located AT the service entrance.  The neutral buss bar should be insulated from the metal enclosure.

[Sahib]

pounce wrote on Thu, 04 November 2004 19:30

Sahib wrote on Thu, 04 November 2004 14:13 pounce wrote on Tue, 02 November 2004 18:56 so i'll put the question out this directly. if i can only afford one of the following, which would be most advisable for clean power in a personal project studio... isolation transformer balanced power supply Balanced power supply as it also provides complete isolation from the mains. However, you have to be very very careful with balanced power supply in terms of wiring and grounding of your studio. Cemal i'm sure you are right. i would have one of my electrician friends help do the install. it looks like balanced power and a star ground system are a good idea. even for my modest personal project space. but what do you think i should bear in mind for this transition? what concerns should i have? i'd appreciate any info.

Paul,

John has covered so much that I do not think I can add very much. However, before you think of using any isolation transformer or balanced power supply there are very basic things that you should do.

First is to have a completely seperate power line straight from the main distribution panel (where the meter is) to your studio.

The cable for this line should be 2 cores for live/neutral + metal shield-screen for earth connections ( for single phase). As John mentioned the neutral should be completely isolated from the main distribution panel chasis.

Also the route that this line follows is very important. Although it is screened, still avoid running it next to other lines. You should make sure that there is at least 8-10 inch distance between them

No lights, no coffee machines etc. to be connected to this line. Nothing but only your recording gear. You must have a complete isolation.

Coffe machines, photocopiers, printers are the main source for causing harmonic distortion on the mains. As harmonic distortion effects the performance of transformers, any equipment that utilises transformer on its power supply stage will be effected in some way.

The lights are also important. No fluorescant lighting or lighting that uses electronics/dimmers etc. in the studio, even though they operate on a completely seperate power circuit. They are the source for RF noise. Just use simple tugnsten or halogen lighting but mains only.

Once you do that you can be sure that you now did everything you can to bring the power to your studio with minimal exposure to external polluting factors. Well, there is one more which is having a dedicated earth completely seperate from the one that is provided by your electricity supplier. However,since you are operating from home this is out of equation.

Now you have the power in your studio and trying to make a decision on whether you should go for the isolation transformer or balanced power supply.

My choice would be to use a balanced power supply as I mentioned before it also provides isolation from the mains. But on the other hand John's recommendations on some equipment not liking it should be seriously taken into consideration. Again as I mentioned before connecting your equipment to the balanced power supply requires extra care. Text book precautions such as star grounding etc. should be followed. Also do not forget no filtering system will help the hiss and hum that is generated by the electronic circuitry of your equipment.

We have a small project studio. We wanted to use a balanced power supply but wiring regulations do not allow it in the UK. So we did our own mains isolation and filtering. We used two identical transformers wired back to back with RC filter in the middle. We made 3 seperate units, supplying to PC, monitors and the  outboard all seperately and it works fine and our system is definitely running quiter but it does not provide a complete isolation.

Cemal

[hepcat]

Why are you bothering? Are you having power problems? I have designed and installed power systems in every scale of facility, and have yet to see a home studio that needs anything close to what you are talking about. Eliminate all audio wiring faults (=cheap) before you start throwing money at power conditioning. You are much more likely to have surge and EMF problems that can easily be solved with a good suppressor and filter than you are to have mains power problems. Don't run the blender while you are cutting vocals! There is no way for you to dedicate a leg of power to audio only in a regular house / apartment, and the unbalance to the line could be unsafe, so forget that. If there is no grounded outlets available, a simple 120 / 120 (if you are in the USA) true single phase isolation transformer with the neutral leg tied to a good ground on the load side will work fine. Make sure this ground ties to the service ground in the power panel! There is almost no circumstance where a "truly" isolated ground is safe. I usually run a series of ground rods spaced at least 6' apart between technical ground and service ground, this sinks any currents that could make their way into either system, while eliminating any hazardous conditions.
If you want balanced power, just set all your gear to run at 220 and get at 220 outlet installed! (I agree that balanced power is a pain in the ass, it works fine until you put in a piece of gear running off unbalanced power, and is impractical to do legally, I usually use a 240 or 208 to 120 transformer and run the whole facility true single phase).
Good Luck!

HepCat

[pounce]

let me throw this in. i am moving. i suspected this would happen, now it's in process. just to a bigger house in the same town.

this will mean some upgrades in terms of space and layout for my personal studio space. and this provides a small budget to do the walls and electric and all of that however i'd like. so i get a nice empty box to start with. so this advice is based partly on the idea i am starting over and have some budget to do this.

having said that, i just want to get a good and clean power. i work in a space across town that uses a furman it-1230 (if i recall the model number correctly), and it's wonderfully quiet all around. perfect power, no hum, low noise all around. i would like to have that stable of a situation for myself. balanced power works there, and i supposed it would work for me. while there may be solutions full out commercial spaces use that are beyond my means, spending lets say two grand getting the furman balanced power thing installed into a new room is totally in the budget. and if that works so well across town i figured it would work for me.

i do have some older keyboards. i would need for them to work with balanced power. i know ups's don't work with balanced power, but hadn't run across any gear in the other studio that didn't work fine with his it-1230. so given that i'm moving into a new room in the near future, and want to start with things done right, isn't this still a good way to go? all the info about balanced power suggests stable digital clocks, no hum, low noise stable power all around. and i can run my room on a nice single dedicated circuit. seems like it would be a good move. am i missing anything?

[Terry Demol]

hepcat wrote on Fri, 12 November 2004 04:18

Make sure this ground ties to the service ground in the power panel! There is almost no circumstance where a "truly" isolated ground is safe. I usually run a series of ground rods spaced at least 6' apart between technical ground and service ground, this sinks any currents that could make their way into either system, while eliminating any hazardous conditions. HepCat

WRT isolated grounds I totally agree. You need a *low impedance*
ground connection for isolated grounds which most shallow earth
grnd rods are not.

The following link gives some perspective on true low impedance
grounding and what is actually required to get it . I don't see
anyone here doing this sort of thing but it's worth a read.

http://www.cpccorp.com/deep.htm

Cheers,

Terry

[Brian Roth]

One thing to keep in mind is the issue of electrical "codes", with the NEC being the "book" used in almost every jurisdiction.

If you install a seperate set of ground rods for the technical power, NEC *requires* that it be also connected to the main grounding node for the building, typically at the main service entrance panel.

Bri

[Bob Olhsson]

A great trick is to isolate the computers, monitors, lighting and fridge rather than the audio!

The most important thing to do is having all of the AC and ground connections tightened up and, if necessary, cleaned. 60 year old loose, extremely corroded AC connections are amazingly common.