Unbalanced studio design... tips, tricks, and pitfalls?

lo.fi.love

lo.fi.love

Functionally obsessed.
I'm designing the audio wiring system for my unbalanced, -10dB home studio. For a number of reasons, some of my cable runs will have to be upwards of 20 feet for a signal's "total trip". I know that it's best to keep unbalanced runs as short as possible, and 10-12 feet seems to be the longest that most people are comfortable with, but I want to know how long you can go before real problems start to occur.

I also want to know what else I should consider when designing this system. All of the power for the mixer and other recording equipment will be coming from the same circuit, maybe even one single outlet. Should I get an isolation transformer? What about a power conditioner, and which kind? Clearly the goal is to keep as much radio frequency interference out of the audio signal as possible, and to prevent ground loops from occurring.

And speaking of ground loops, what are some good rules of thumb to avoid causing ground loops? I've read a few suggestions - including inserting a Ground Lift device of some sort, but I'm not sure if this is either a good idea or when it would be appropriate to do so.

This is going to be a massive project for me, and I know that I'm going to be spending a good chunk of money. If anyone can help educate me on what I'll need to do on this journey, I'll REALLY appreciate it. I'm confident that I can figure it all out, but I want to learn as much as I can beforehand so I don't end up wasting time and money.

Thanks!!
Jeff
 
lo.fi.love said:
I'm designing the audio wiring system for my unbalanced, -10dB home studio. For a number of reasons, some of my cable runs will have to be upwards of 20 feet for a signal's "total trip". I know that it's best to keep unbalanced runs as short as possible, and 10-12 feet seems to be the longest that most people are comfortable with, but I want to know how long you can go before real problems start to occur.

I also want to know what else I should consider when designing this system. All of the power for the mixer and other recording equipment will be coming from the same circuit, maybe even one single outlet. Should I get an isolation transformer? What about a power conditioner, and which kind? Clearly the goal is to keep as much radio frequency interference out of the audio signal as possible, and to prevent ground loops from occurring.

And speaking of ground loops, what are some good rules of thumb to avoid causing ground loops? I've read a few suggestions - including inserting a Ground Lift device of some sort, but I'm not sure if this is either a good idea or when it would be appropriate to do so.

This is going to be a massive project for me, and I know that I'm going to be spending a good chunk of money. If anyone can help educate me on what I'll need to do on this journey, I'll REALLY appreciate it. I'm confident that I can figure it all out, but I want to learn as much as I can beforehand so I don't end up wasting time and money.

Thanks!!
Jeff
Click to expand...

I have some unbalanced runs that sre 20' without any obvious noise or signal loss. All of my unbalanced runs are high quality 18 gauge 100% shielded cable. go to http://best-tronics.com/mm5/merchan...BMI&Product_Code=CA-0441&Category_Code=GUITAR I make up most of my own cables. An Isolation Transformer is a good idea. see if you can get one with Surge Protection and Ground Fault Protection. I bought a Furman Balanced Power supply that does it all, it was $1700 though. But my studio is absolutely quiet. The Ground Fault Protection, GFI, is important to protect from any voltage mishaps in your studio. They will trip at the slightest voltage fault. Also because I have GFI protection I use ground lifts alot to eliminate those damn ground loops. The GFI will protect you if equipment is not grounded. The whole studio which is in another building is shielded with aluminum flashing under the siding and roofing. This is connected to 4 ground rods to produce a Faraday Shield. It keeps out all sorts of interference. It is amazing how much noise comes from satellites. There are alot of tricks I have learned in 15 years. I am a liscenced electrician with a degree in electronics. Some things I have learned the hard way. Feel free to ask any and all questions, I am fascinated with the subject.
VP:cool:
 
lo.fi.love said:
I'm designing the audio wiring system for my unbalanced, -10dB home studio. For a number of reasons, some of my cable runs will have to be upwards of 20 feet for a signal's "total trip". I know that it's best to keep unbalanced runs as short as possible, and 10-12 feet seems to be the longest that most people are comfortable with, but I want to know how long you can go before real problems start to occur.

I also want to know what else I should consider when designing this system. All of the power for the mixer and other recording equipment will be coming from the same circuit, maybe even one single outlet. Should I get an isolation transformer? What about a power conditioner, and which kind? Clearly the goal is to keep as much radio frequency interference out of the audio signal as possible, and to prevent ground loops from occurring.

And speaking of ground loops, what are some good rules of thumb to avoid causing ground loops? I've read a few suggestions - including inserting a Ground Lift device of some sort, but I'm not sure if this is either a good idea or when it would be appropriate to do so.

This is going to be a massive project for me, and I know that I'm going to be spending a good chunk of money. If anyone can help educate me on what I'll need to do on this journey, I'll REALLY appreciate it. I'm confident that I can figure it all out, but I want to learn as much as I can beforehand so I don't end up wasting time and money.

Thanks!!
Jeff
Click to expand...

As someone that fought noise of every kind in the 80's, 90's and beyond, when I decided to re enter the analog word I knew how difficult it can be to make everything quiet.

I bought the Furman IT20 isolation transformer prior to setting up my "NEW" console a couple years back. My advice to anyone concerned with hum and interference is to spend the money and get a real isolation transformer. It's expensive but worth every cent if you are serious and want to do away with noise issues once and for all. The 20 amp version will handle everything. It is massive and the real deal. You will be truly separate from a direct connection to the powerhouse, powerline noise and you will be able to forget about ground loops.
http://www.sweetwater.com/store/detail/IT20/.

If you plan to use a regulated supply, ( http://www.sweetwater.com/store/detail/AR20II/ ) it MUST go ahead of the isolation transformer because otherwise, it would never see more than 60 volts and continually shut down because it could not buck the current enough. If you plan to use UPS for computers, do not put them downstream of the isolation transformer. It also would continually shutdown.


When hooking everything up, have everything in the studio on, turn the monitor volume up to about 3 oclock and wire in 1 only piece at the time. If any new noise is added at any point, stop and figure out exactly what the problem is before pluging in something else.

Regards,

Danny
 
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It just depends on how noisy your EMI environment is. Mine is horrible so I don't allow unbalanced lines in my studio for that reason. OK, a 3' RCA cable from my CD/tape player to the amp, but that's not part of the audio production chain, just playback.

Your studio might not be noisy, you just have to try it and see.

A common misconception is that the only source of interference is a "ground loop". Yeah, come to my studio and I'll show you 60Hz hum on battery-powered gear. Also, I see people saying noisy microphones have a ground loop. That's impossible if you think about it.

But yes, everything in a single outlet is preferable (provided you don't overload the circuit). The AC line is not the biggest source of noise (it ought to be well filtered before it comes near your audio). A real ground loop can be; induced EMI is the other. If you have eliminated actual ground loops and still have EMI, your choices are:

a) find the source of the EMI--it might not be anything in your studio or sometimes even your house.

b) use balanced lines.
 
Thanks for the great responses. I'm still digesting all of it.

I'm not terribly keen on spending $1,700. I'm guessing that would be necessary in an extreme situation.

I suppose that the best, and sanest, approach would be to wire everything up and see what happens. Before I get to the point where I'm troubleshooting and eliminating issues, is there anything that I should do while I'm connecting everything? Tips on making snakes? Things to avoid?

In a perfect world, everything I own would be +4 dB, balanced. Almost everything that I own, though, is -10dB, unbalanced, connected with RCA connectors. You could say that I own the 1987 TASCAM Floor Display...
 
lo.fi.love said:
Thanks for the great responses. I'm still digesting all of it.

I'm not terribly keen on spending $1,700. I'm guessing that would be necessary in an extreme situation.

I suppose that the best, and sanest, approach would be to wire everything up and see what happens. Before I get to the point where I'm troubleshooting and eliminating issues, is there anything that I should do while I'm connecting everything? Tips on making snakes? Things to avoid?

In a perfect world, everything I own would be +4 dB, balanced. Almost everything that I own, though, is -10dB, unbalanced, connected with RCA connectors. You could say that I own the 1987 TASCAM Floor Display...
Click to expand...

I have just recently discovered that there is nothing wrong sonically with -10. I always assumed it was inferior to +4. Actually balanced lines are theoretically inferior to unbalanced because of the coloration of the balancing circuits or transfomers. These circuits and transformers are only there to make the circuit balanced and reject noise. They are essential in long commercial installations. In our small fixed studios -10 is superior. The tradeoff though is a lot of work to eliminate noise and ground loops. I know I will be hanged for blasphemy but I read this in a Tascam publication and I searched google where I also read the same basic idea.
VP:rolleyes:
 
I run -10 unbalanced for interconnection, except for mics. I don't like to run anything over 20 ft unbalanced, but in the room I have now I don't even need that much length. Everything is in close proximity, and I only record myself, or a friend or two these days, so my space needs are modest.

I did run a separate AC line from the main breaker box in the garage back to the room, so there is nothing else on that line but the studio outlets. No trouble with hum, RFI or other noise.
 
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