just a home studio problem/solution I had. A very extreme issue probably not found in a pro studio but here it is.....

My home studio is on 2nd floor and get very very warm in the summer and the house HVAC doesnt work well up there. So I installed an in wall AC unit that runs of the house 115vac where the main breaker is on the extreme other side of the house so there is a lot of Romex wire to the ac unit. The result is that every time the AC compressor starts, there is a large current surge and the AC voltage drops. Its not a problems for most things like the PC (which accepts a fairly low AC input anyway). But other electronics, especially ones that operate from wall warts are do immune and will drop out. In parituclar my floor effects pedal for guitar will drop out and reset each time the AC goes on. I could easily observe this drop when viewing the meter on my Furman power conditioner (which obviously provides no protection in this case)

So one option was to turn off the AC during recording, another to rewire or add more wire from the box to the AC. In my case fairly easily done since all the wire is in the attic which is 12ft high (another floor someday) and easy to get too.

I tried a 3rd option which was to run everything PC and music related off of a uninteruptible power supply (UPS). I bought one on ebay cheap enough that will provide uninterruped AC power through momentary dropouts like the AC causes and backup for 45 minutes or so. This provied the added benefit of backing up my PC long enough to save files etc if there is a long term power drop out.

It works great. I can observe the UPS kicking in to keep an uninterrupted 115vac power during each A/C kickin and recording et all is totally unaffected by the power transitions now.

The proper solution is the beef up the wire to the AC....maybe someday when its not so hot in the attic. But the UPS is a nice bandaid and give me the added benefit of power backup during long term outages and allows me to save files that I was working on during the outage.

Hope that helps some

Wiring in most homes is not particularly good, especially older homes. For years we had a problem with dimming lights, computer warnings, etc, whenever the washer would kick in. I finally got fed up and ran a separate 20a breaker with 12g wire for the washer, and that eneded the problem.
I foolishly "volunteered" to wire my mother-in-law's new house (she's done a lot for us, so I wanted to return the help) and wired the whole place with 12g wire and 20a breakers, with separate circuits everywhere. The electrician who came out to connect the outside feed and meter said he wished his house had been wired that way.
I won't do that again unless it's my new house (yeah, that'll happen...)

Hey uhh something I just tried here recently. It was a gamble with the money but it definitely made a difference:

Furman makes this thing called a Power Factor Pro. It's a floor unit (almost like an oversized stomp box) that provides line conditioning and filtering. It's marketed towards guitar players.

The unit seems to provide a certain level of "stiffening" or tightening of the tone. I would make a comparison to those car audio systems that use those big filter capacitors to tighten the sound up. It was an audible difference and the first time I've ever seen a line filtering product actually change or improve the sound of my equipment. Was it worth $230? I haven't decided yet since I've only had it a few days. Will live with it for a little bit and see.

update (9/3) - well, I've had this unit for about a week now and am convinced it was worth the money. It really makes just about anything you plug into it sound better - tighter and more focused. It even made my Line 6 Pod sound better. I can't recommend it enough. Wish I had two of em now. Do yourselves a favor - if you have the means - and check out one of these things. If you're not convinced, you could always sell it on Ebay but if you're like me, you won't want to. I think they make a rack mount version too.

In addition to a couple of Furman PL8's, Furman outlet strips, and an APC 1500 W UPS for the DAW, the best thing I did in my small project studio, which is in an old guest house, was to have an electrician run a dedicated 20 amp circuit direct to an outlet that everything that is connected in my studio is plugged into.

This has reduced my noise floor considerably, removed ground loops etc. The ground is straight from the service into the box, not connect via junction boxes or conduit.

Having played every stinking dive bar in the tri-state area for the past 30+ years, I can tell you without reservation that the best thing you can have is a Furman voltage regulator (the AR1215 or equivalent). Digital gear doesn't work so well on 90 vac.

As far as the other noise is concerned, flourescent lights and dimmers and fans and air conditioners and refrigerators abound in most clubs and bars. Live sound is usually the last thing they think of when wiring the building. You could try an iso transformer as a potential defense but they are heavy suckers Usually, a little bit of noise or static in your guitar rig is easily outweighed by the fact that:

1) the soundman is a drunk (or didn't show up)
2) the patrons are all drunk and could care less
3) The stage is wired with jumper cables (I have actually seen this)
4) only three people showed up for the show
5) the fight out in the parking lot is more interesting than your show
6) the bass player only knows the first 30 seconds of each song
7) your drummer forgot his snare stand and has to hold the snare between his legs all night
8) you're only gonna walk out that night with twenty bucks in your pocket (before expenses)
9) you only have three mics and one of them was just run over by the van
10) someone stole your $3,000 Les Paul at the last gig and you had to borrow an epiphone until you can save up enought money to buy another guitar

I have personally witnessed all that and more. I could have written the Spinal Tap movie. Forget surge protection. Will not help you one little bit. Buy the Furman first. If you have enough money left over, buy an iso transformer and keep it in the car if needed. Good luck!

You know...I just had a thought here. I used to be real active in ham radio, and to reduce emi and rfi one of the first thing any new ham did once he decided to upgrade from the little walkie talkie handhelds to a big system was to build a ground bus. Because of all the reasons mentioned, the ground on a home or business is rarely Absolutely clean. It is however, insanely easy to build a completely clean ground. drive a piece of very thick copper pipe or a very thick copper rod down about 8 feet I believe, double check to be sure though. and then you just what basically amounts to some real thick copper wire (it's pretty thick stuff, not cheap - you may find copper scraps more useful...the time honored tradition of hunting for bargains and going to junk yards is useful here) then wire it through your house, seperate from the electrical stuff. Possibly removing the main electrical ground from your studio plugs that are going to use this and instead wire this ground. Voila! Perfect ground. This of course was for RFI, aka earth ground for antennas, but it should work equally well for electrical ground. If you're thinking of doing this, look up the instructions in a ham radio periodical or an electronics periodical. It's intellectually simple, but if not done right you could **** some **** up really bad. Be careful and good luck...hell I might have to do this myself, I haven't had a dedicated ground bus since I moved. My experience is that in radio, you can hear a signal you'd never have been able to hear once you remove all the noise from your ground. It should translate similarly to audio - I've found that most of my radio knowledge has.

All comments here are advice only. Don't do anything above your knowledge or experience level, it's stupid, you'll get hurt, and I don't wanna get sued.

Interesting observations there Psych.  Ham radio background here also.  I had a lot of trouble here in my home with control boards going out in every piece of equipment in the place: dishwasher board failed, AC/Heater control board failed twice, VCR power supply failed.  What the heck?  I asked the AC guy that put a control board in my attic unit what could be the cause of the problems.  He mumbled "maybe a bad ground."  So I went outside and checked the earth ground.  The clamp, a cheapo version that you tighten with a flat head screwdriver, was so loose it spun on the ground rod!  Off to the hardware, bought a HEAVY clamp that you tighten with a socket wrench.  Soaked the ground cable end with Caig deoxit and polished the head of the ground rod.  Made the connection and torqued it very tight.  Not another electrical failure since.

Moral of the story:  check the cheap fixes first!