How to minimise electrc noise when playing and recording music?
If the supply to the music room is Radial, (not Ring), would this eliminate any buzzing due to there being two paths for electricity of different lengths and different resistances/impedances?
Or disconect the earth supply and use a separate earth rod in the music room?
Quite, you wouldn't for serious recording/playback be using any PC with an internal card unless its in the Digigram class, so an external box is a must!...
How to minimise electrc noise when playing and recording music?
Can't see it making any difference. Even with a dedicated circuit, you will still see noise that originates on other circuits.
If anything that would give you a higher impedance earth. You would also need to make sure all supplies had adequate RCD protection as well.
More to the point, how much of you equipment is actually earthed anyway?
Feeding all equipment from the same socket (via multiway leads) can help a little. Not running CRT displays close to any wiring (mains or audio) can make a big difference as well.
Unfortunately the inside of your average computer is about the last place you want to try an handle low noise audio (at least before you have got it into the digital domain). External ADCs with fibre IO to the computer (or at least opto isolated IO) will give a big step up in quality.
That's not a cause of buzz. In fact 2 parallel paths reduce the risk of electrical noise caused by a poor mains conenction somewhere.
IMLE on this, mains borne noise isnt the place to look. The mains is noisy, you're not going to solve that and don't need to. Any sufficiently good equipment will be able to reject mains borne noise, both in the psu and in the audio leads you use. Use of poor leads is a common problem in home studios, and no, you dont need gold plating. What's primarily needed for leads is robustness, good screening (eg good 50ohm coax) and rubust plugs, ie 1/4" jack or rca phono. Don't even think about using 3.5mm jacks.
Audio cards inside a computer case could be metal screened to reduce noise pickup if it happens. Low level signals such as mic should always feed a differential input via twinax.
If you're using corner cutting equipment, you've always got noise gating to improve things.
Nope and dangerous unless you take the correct precautions but as it won't do anything for your problem(s) there is little point.
Take a read of:
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diagrams are a bit poor but the information is good. Curing noise problems is not easy but starting with the correct understanding of the basics helps an awful lot.
Agreed but the OP seesm to think that simply earthing everything to the same point will improved things. It might change things (and could become unsafe, FSVO "unsafe") but it probably won't as the root cause of most trouble is basically down to the resistance of the earth connections.
Posting a few minutes recording of the noise somewhere would also help so that we can assess whether it's mains hum (as the OP implies) or a different source (as others have assumed).
I want to run a new wire the 25 meters to the music room for recording music, and at other times for connecting a P.A. The plan is a 4mm Radial with a socket at each end of the room. If i've understood correctly al the noise comes up the Live and neutral wires so there'd be no advantage in having the earth independednt from the rest of the house's earths. The existing house wiring is of many ages and types.
Hi George, a bit of input from my experience in building something similar, hope it's useful (and that I'm not instantly shot down in flames):
Mine[0] has a 10mm (shower cable size) sub-main from a couple of floors below (sharing the loft with my ham gear and workbench) with a 32A breaker in the main consumer unit, feeds through a UL-listed 40A mains filter (about the size of two baccy tins, in its own enclosure) to a small CU with a 30mA RCD and 3 off 16A MCBs feeding 3 radials to pairs of double sockets (and another each to the ham gear and workbench), shares an earth with the rest of the house, admittedly kept as short as poss. in heavy (16mm) earth cable to minimise the earth impedance. My big problem is the airport radar a couple of miles away, so I may end up putting a Faraday cage behind the loft insulation... Even then I don't think I'll be able to use my ham radio gear with its 200W transmitter at the same time!
Assuming (from the 25 Metres bit) that yours is in a separate building, a low-impedance[1] local earth would be a Very Good Idea, and if you can afford it, go to an isolating transformer[2], separate the earths at that point and locally star-earth the centre-tap and your local power on the secondary (studio) side - this is/was common practice in pro studios (I used to be professionally involved with 'em, many moons ago). Make some LARGE CLEAR labels warning that neutral is 120V above earth potential though!
With the 25m sub-main run, you'll need overcurrent protection (MCB) and an RCD at the "head" end, preferrably a time-delayed (100mA?) RCD to give discrimination between a fault on the submain and a fault local to the studio - which should have its own RCD and MCBs, the MCBs needing to be
2-pole due to the neutral potential if you go with the isolating transformer.
Some Other Considerations:
Fluorescents (particularly CFLs) and Dimmer switches[3] for incandescent lights generate a lot of interference - avoid! "Electronic transformers" for low-voltage lighting ditto - use old-style iron transformers, preferably toroidal to minimise the stray magnetic fields;
You are runing everything you can in balanced low-Z cabling, aren't you?
Earth loops in signal cables will pick up a lot of interference just where you least want it, go for star-wiring there too, if necessary you may have to lift the earth of one end of **signal** cables (where signal earth is connected to power earth) - much easier with balanced audio!
You are runing everything you can in balanced low-Z cabling, aren't you?
Physically separate the audio, data (assuming PC use) and power cable runs - a foot minimum, more is better!
You are runing everything you can in balanced low-Z cabling, aren't you?
Feed the lighting separately (or from the non-RCD side of the local CU if it's a separate building) so a dud amplifier won't leave you groping in the dark...
You are runing everything you can in balanced low-Z cabling, aren't you?
PCs put out a lot of (acoustic) noise, if you'll have one in the music room it's worth building a soundproof cupboard with a fan ventilating it to the outside world in which to hide it, a cheap UPS is a good idea if it's the basis of a recording studio as that way even if the audio gear goes off the recording's safe!
If, like me, you have a Shed of Danger with welding gear, machinery on VFD's etc. give it its own local earth too (make it a TT installation with separation between the sub-main earth and local earth), to minimise the amount of crap coming back along the sub-main's earth and infecting your main (shared household) supplier's earth!
Perhaps a good idea would be to post some of your Q's on alt.music.home-studio, there could be plenty of opinions there if it's not totally submerged in the spam? Feel free to email me off-group (remove the obvious spam avoidance) if you want to, although it'd be good to correspond on the group for others' benefit!
Using a separate earth for the tech equipment is common practice in recording studios. However, they are likely to have other heavy loads in the building like air conditioning.
It makes little difference. Its just missing the point.
Forget it. An iso reduces the noise that comes down your mains feed, but increases the locally generated noise on the line due to its higher impedance.
Secondly, trying to clean up the mains is of limited point, it just isnt where the solution lies.
Having in the past built some recording studios and radio broadcast studios, I can tell you that most all of these were run off a simple ring main, nothing any different than what you'd have at home!.
No fancy cables, no earth plates buried in virgin Vampire oil, nothing from Russ Andrews, no isolating transformers, no filters even, nothing odd or unusual at all.
NO extraneous noises, no clicks, hum's, bangs, pops, radio and or taxi breakthrough either..
All down to one thing. Professional equipment using audio interconnects!..
It was really that simple.
However if you try to use domestic equipment for this sort of thing unless you are very aware of things like Hum loops etc, then do expect trouble especially if you have most anything more than a few metres, feet even apart.
The problem usually happens with unbalanced interconnects if that the output of one piece of equipment feeding another manages to get more than the one path in circuit which -adds- to the signal.
I can't give a detailed explanation of that here but if you are trying to use domestic unbalanced equipment for what your trying to do then unless you know exactly what your doing then I am very much are of the opinion that it won't work properly and it will be very problematical.
If you want further help then give us a description of the equipment in use. If theres a mix of that, domestic and pro semi pro even then that sometimes can be used and made to work but there are other problems like level matching etc which can be awkward to overcome.....
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