Hello Ohmisch

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Either replace the Thermostate or have an electrician fit an (?) [="http://www.dict.cc/englisch-deutsch/anti-interference.html"]anti-interference[/]="http://www.dict.cc/…"]anti-interference[/] [[url=http://="http://www.dict.cc/…"]capacitor[/]="http://www.dict.cc/…"]capacitor[/] (?). I don't know, how it is called in English.
In most cases that solves the problem, caused by an electric spark each time the unit switches on/off. The existing one is probably defective.
You might want to have a look at surge protecting and interference suppressing power strips for your setup, which filter the noise of the powerline.

The only problem I see with getting one of the surge suppression filters for a single appliance, is that they primarily are there to protect the device that's plugged into it. Most of them will indeed stop some of the back surge from the relay kicking in/out, but much of the surge still gets pushed/reflected back into the AC line. Most electricians are not really familiar with installing the correct type of filter for this situation - which is a power filter that sits in the panel. ([[url=http://[/URL]="http://en.wikipedia…"]Surge protector - Wikipedia, the free encyclopedia[/]="http://en.wikipedia…"]Surge protector - Wikipedia, the free encyclopedia[/]) And even then, if the appliance is on the same circuit as your audio gear, you will still have that surge/spike on the entire circuit.

Most of the consumer grade appliances for surge protection are pretty cheaply made and disposable... and quite often need to be replaced every 6 months... if not more often.

The best resolution is to have an electrician put (assuming you are in the US/North America) your audio is on it's own dedicated circuit... where the audio gear is on it's own phase, and everything else (refrigerator, lights, etc.) is on the other phase... again, assuming you are on a conventional 240 single phase electrical service.

As an added safeguard, I would suggest purchasing an isolated & balanced power, conditioning unit, such as are made by Furman... but there are other good manufacturers out there.

It's not uncommon for a small room to have all the receptacles on one circuit. Especially if the room wasn't originally designed for technical use, or other high-power applications in mind - like power tools, cookers, heaters, etc.

As Big K says, your next counter-measure would be a good surge protector / line conditioner [ ETA, Furman, TrippLite, Juice Goose ] You should have your computer on a UPS (uninterruptible power supply) anyway, does it have any form of surge suppression or line filtering?

The big question is whether or not the receptacles are properly grounded. Unfortunately, just because they take a 3-prong plug does not mean they're really grounded to anything. Not only is it a safety issue, but without a solid ground, even the best line filter will be seriously limited in how much it can help get rid of junk in the power line.

Or Plan B, do what my buddy had to do: Unplug the fridge while you're recording.

And I would certainly second Max's suggestion - if you're serious about fixing this problem you should consult a licensed electrician so you know for sure what you're dealing with.

Refrigerators draw down a large amount of current on the startup of the compressor. At the very least if you can put the refrigerator on it's own circuit by perhaps running an extension to another room or to a light socket with an adaptor (since the lights are likely on a separate circuit).
If this is a small dorm-sized refrigerator you can do what I did and purchase a unit that utilizes super-conductor technology... it has no compressor, no large current draw-down and runs silently! The perfect studio refrigerator. Mine is made by Avanti and was under $100 through Amazon.
Jeff

Are we over-looking the obvious solution here? Unplug it when you're recording. Just don't forget to plug it back in when you're done. :)

An unplugged refrigerator will keep stuff cold for hours if you don't open it a bunch.

Wow, many and good comments.. nice :)

I have only that one room, with a single power-circuit it appears
Now I've noticed that the sound actually only happen when the refrigerator stops
The fridge is a small Whirlpool ARG090GWP. Just bought it and don't want all that transport-hazzle again :/

I called an electrician I know.. and he did'nt really know much about noise-capacitors (or whats the name), but he's just a "regular" all-round electrician.

I also thought about using the light-power-line somehow.. maybe I'll try it. But this is a building packed with rooms like mine, and I doubt that there are two fuses pr. room

Unplugging the fridge when recording is not an option as I'm recording many many times per day ;)

Btw, i'm in Denmark
The wallplugs in the studio have ground, but we crazy danes don't ground appliances much here. Have good RFI/HFI (?) security I guess..
I could ground the computer or the external soundcard maybe.. but is'nt it risky to mix grounded with non-grounded devices?

Not every device needs a dedicated earth ground wire. Many devices have protective insulation or are drip-proof.
Any standart electrician knows about this little spark catcher ( capacitor ) at switches, and motors. You find them in hairdryers and vacuum cleaner, as well.
They are maybe 3$ or less.
I vote against turning the fridge off. If you ever forget to plug it in again, you might loose more cash on bad food than fixing the problem would cost.

In the US musician are forbidden by law to have anything in their refrigerator but beer, a jar of mustard from the Clinton administration, and a piece of cheese that looks "lively."

little spark catcher ( capacitor )?

are you taking about a MOV (metal oxide Varistor) or TVS(transient voltage suppressor)?

Some MOV's look like caps, that won't fix your problem. It will just shunt it, but to where.... you have no ground? So it will go back on the neutral to ground....same problem.

Run a new circuit with its own breaker, you can run the wire surface mount if you have too.

Think racewayhttp://www.ampnetco…

Any qualified sparky should be able to do that....

Again, putting in a new circuit with ANY kind of suppression device, other than a hybrid MOV/GDT/TVSD placed on the same phase, WILL still put that reflected energy on that phase... and thus will still be present in the audio circuitry on the same phase.

It may be common in the EU to use the devices that are essentially a surge suppression circuit that consist of a filter cap and MOV that shunts the surge around the relay open/closure and compressor surge... but for the most part, they are not legal in the US.

Do a little experiment: get yourself a short-lead mains socket board that has built-in surge and overvoltage supressors and try plugging your fridge into that. Ideally you would need a board with a symmetrical suppression arrangement that suppresses surges generated by devices plugged into the board and not just surges coming in down the mains.

Let us know the result. If using the suppression socket board has little or no effect on the clicks you are hearing, it is likely that you have a transmitted electromagnetic interference problem rather than a conducted one, and the subsequent approach to tackling it will be different.