Recording studio wiring

[JonAW]

Hi Guys

I've been asked by a neighbour to wire his new recording studio. He is operating out of his garage at the moment and is complaining about small electric shocks and major 'noise'. As he is looking to go semi-pro he is converting an old barn and has asked for me to do my best to kep the noise down. I am a fully qualified sparky ( before anyone asks).

Anyway the studio will consist of 4 rooms, a lounge area, a mixing room, a sound room for the band and another small room for the drummer.

What I am thinking of proposing after a good bit of research on the net is the folowing:

A new 16mm supply from the origin (16mm required only for low impedance levels)
A new dedicated earth placed outside the building with as low impedance as I can reasonably get.
A consumer unit for supplies to the oil boiler, lighting and general power.
A consumer unit fed from a 20 or 32A UPS (load unknown), which then feeds power outlets to the soundroom, recording equipment and computers.
All circuits will be wired in SY cable with the screen earthed at the consumer unit including lighting. All cabling will run as straight as possible with minimal crossings. Any crossings would be at right angles.
A ring main wired in Data trunking will be put in the sound room. The cable will be 4mm.
The same with the mixing room only all sockets will be kept as close together as possible. The cabling for the ring main would be run side by side instead of in a loop around the room to prevent equipment being placed inside the 'loop'.

Another method is to forget about the UPS and run 20A radials to a socket in each the mixing room and the sound room. From that a Power conditioner would be plugged in allowing a perfectly clean supply along with ground loop separation to each component. The only problem with this is that all sockets would be in the one area instead of being around the room.

Does anyone here have any experience of wiring a recording studio?

Any advise or help would really be appreciated.

thanks

Jonny

 

[jeremy]

No experience in this field whatsoever but will follow with interest. I used to install high end car hifi and noise was THE problem what with HV spark plugs , alternator etc. What was called earthing in relation to cars would I guess relate to bonding now. I'm guessing that as big an earth spike/mat as possible and keep everything shielded. Sorry I can't help but there must be someone here who can. Best of luck!

 

[martysparky]

potentially lots of computer technologies in mixing room or even live room, will you be using high integrity cpc?
You might want to consider route as sound engineers some times like to fill voids between ceiling and floor with concrete for sound proofing purposes.

I know noise is a problem resulting in a hum on the mixing desk etc from ground loop or electrical field but I thought the answer was a filter or mains conditioner.

This noise can come from devices plugged into the mains and multiply plus some devices more of a culprit than others.

I'm not experienced as such but have worked in recording so I will be watching with interest too.

 

[JonAW]

Hi Guys

potentially lots of computer technologies in mixing room or even live room, will you be using high integrity cpc?

I have never heard of this earthing system until now. I took a quick look at the net and what I think it is, is taking a 2nd earth to all outlets, connected to a diffenent terminal where possible. Is this correct? I assume it is mainly used because electrical equipment can give leakage to earth. If this is the case then yes I will install high integrity earthing. I would proabably buy 4core sy instead of 3 core and use the 4th core as the 2nd earth.

Another quick question, I've been told that CY cable has a better screen than SY, I'm not familiar with CY to know, so what do you guys think? Can it be got in 4mm etc.

 

[Spudnik]

High integ earthing is required for all circuits likely to feed equipment with higher then normal earth leakage.

Because of the high EL, ring finals must have their cpc's terminated in separate terminals on the bck of the socket and CU.

Radials must also have a separate earth run, also back to the CU.

Basically, it is a failsafe against any earth connection coming loose.

http://www.eland.co.uk/ss/electricalcable/controlcable/cable36/cy-controlcable-cable.html

 

[wacko]

And don't forget to think about lamps etc. Throw up a couple of fluorescents and the amps will probably crackle.

Regards

 

[JonAW]

Yep, the lamps have been taken into consideration. He wants 230v 50w spots up.

Thats good info on the CY cabling. Seems like the better choice. I think it may be going a little overboard but I don't want to underspec the system either.

thanks

 

[dragon-av]

I would suggest treat it like a semi induistrial environment and conduit metal box it all out, also in the areas he will need Data as well as power plenty of floor boxes for gear and keep supply as clean as possible with separate circuitry if possible for different loads May want to look at small UPC/power facotr correction/smoothing on the incoming power. However it all comes down to cost

 

[Izzy's Dad]

The noise in audio signals isn't normally caused by earth leakage, although it can cause probs. The biggest noise or hum is caused by an earth loop. The easiest way to overcome noise is to use a balanced power supply for the desk, tape machine/computer.

 

[JonAW]

The noise in audio signals isn't normally caused by earth leakage, although it can cause probs. The biggest noise or hum is caused by an earth loop. The easiest way to overcome noise is to use a balanced power supply for the desk, tape machine/computer.

So what you are saying then is to wire the studio in a normal commercial/domestic style, taking care of cable runs, and use a power conditioner which has a facility to separate ground loops to feed out to the equipment? Is it likely that normal cabling and lighting equipment could cause noise?

Is it possible to have a UPS feeding into a power conditioner for battery backup?

thanks for all the info so far, the customer doesn't have a lot of money so I want to try to keep the costs low, but I think he is going to have to invest in this equipment if he is serious about making the studio work.

 

[Colin Integrale]

Easy, play louder.

 

[DiscoDave]

Watch out for the quality of the lamps and light switches used in the studio and recording rooms, Some gear can hum and buzz as part of normal operation, this can be lamps as much as transformers, although may not create "noise" on the recording equipment it may be noticeable in the recording.

 

[Snakey]

Consider using 2 consumer units and an Isolation Transformer. The first consumer unit (dirty) can feed the lighting circuit and ring main (not to be used for music equipment). The second consumer unit (clean) can feed the mixing room and the separate booths/areas that need sockets.

Each piece of equipment shall have its own socket spurred from the Clean CU. This isolates the earth from any loop. Install a star point at the CU for the earth's from each spur to be connected to. The star point should then be grounded via its own grounding post.

If there is RF interference then consider installing a Faraday Cage.



Any update on this topic?

 

[Deleted member 26818]

Yes two CUs, one clean and one dirty.
No real need to use SY or CY cables, T&E should be good enough.
If you do use 4 core SY/CY cables, make sure that the combined CSA of all the conductors > 10mm², or the high integrity earthing will not comply.
Obviously be carefull about grounding the SY/CY sheath at one end only.

 

[chrishaworth]

I did one a few years ago for Pye Hastings of Caravan (yes - still going). 6mm SWA from house, industrial combined class surge protection unit (absolutely essential), then standard 32A ring and 6A lighting circuits from a garage CU. Only problem was the dimmer for the CFL spotlights which started buzzing in B flat. Replaced that with a switch and everything has been fine since. As far as I know, the audio earth is well isolated from the mains earthing on good kit so no exceptional earthing measures are required. If it's good enough for a man with gold discs on his wall, it's probably good enough for your mate.

Cheers
Chris

 

[SirKit Breaker]

I did one a few years ago for Pye Hastings of Caravan (yes - still going). 6mm SWA from house, industrial combined class surge protection unit (absolutely essential), then standard 32A ring and 6A lighting circuits from a garage CU. Only problem was the dimmer for the CFL spotlights which started buzzing in B flat. Replaced that with a switch and everything has been fine since. As far as I know, the audio earth is well isolated from the mains earthing on good kit so no exceptional earthing measures are required. If it's good enough for a man with gold discs on his wall, it's probably good enough for your mate.

Cheers
Chris

You cant beat keeping it simple, nice one.

Cheers..........Howard

 

[UKMeterman]

Hi,
I would suggest taking a look at Tim Williams' book EMC for Systems and Installations I do not suggest single ended bonding of screens as this can cause more issues than it solves. The customer may be gettinng shocks because of lifted earths on equipments and so on. The correct way to solve these earth loops is to provide a parrell low impedance path to the signal wires, and also ensure that any supply cable has the current return in the same cable, so the loop size is kept down.

I would also suggest looking here EMC Information Centre and have a look at EMC for systems and installations. A lot of the noise can be reduced by proper selection of propper cables and connectors.

There has been mention of an AUDIO earth, what currents are you expecting down that particular rod? Why isn't that rod bonded to the mains safety earth?

Regards

UKMeterman

 

[chrishaworth]

Audio earth = DC 0V.
Cheers, Chris

 

[UKMeterman]

If it is at 0V then there is no currrent...... please take a look at the website pages above. It discusses what is true earth and what isnit..

 

[chrishaworth]

That's like saying a neutral at 0V relative to earth is taking no current. Electronics uses terminology in a different way to LV AC.
Cheers, Chris (ex Electronics Officer).

 

[UKMeterman]

Hi,
Yes I am aware of the difference, most pro audio equipment is designed for a signal to noise ratio of 120 db or more. The signal voltages may be a 1v or so in the respect of line connected equipment CDs and the suchlike and about a 0.0001 of a volt for a microphone, thus the noise voltage should be kept 120dB below these, or 1millionth down. The major issue is that the shield on single eneded connections is also connected to the mains safety earth at both ends, and touch currents and similar can try to flow through the shield. If say the shield of a poor cable had a resistance of say 0.5 ohm, and say 2ma tried to pass that way then there would be 1mV of noise. The trick is to get this common impedance down, use good quality cable with a good braided shield, Vandam cable and nutrix connetors would be good. If need be run another CPC in parrell with the signal cable if the 50Hz hum is a problem.

The audio equipment is only concerned about the voltage it sees at the inputs, if the shield is connected to a ground rod (which will have a significant impedance anyway) it is not releivant

Regards
UK Meterman BEng(Hons.) MSc MIET

 

[chrishaworth]

Now we've established that neither of us are first year apprentices, we can continue the discussion. My main contention is that professional recording equipment does not normally require specialist earthing arrangements etc. In fact the more you pay, the better the filters will be. Rather than paying out a fortune in dual CUs etc., the OP would be better off spending on sound insulation. If the equipment works fine when plugged in at the house, then it should work OK in the studio.
Cheers, Chris

 

[UKMeterman]

Hi,
My point exactly, you just need to think of some basic ohms law, and if there is a hum where could it come from. The main point is do not disconect any mains safety earth from any bit of kit. It may be an idea for some local equipotenial bonding with a nice large earth block and and some 4mm2 connected to each rack by the shortest route. If the OP wants any more ideas please drop me a line.

 

[chrishaworth]

I must have been incredibly lucky that the one I did worked with no problems.
Cheers, Chris