Air condicioning and Coffee machine clicks in audio recordings???

Hello, ive been working in a studio here in Lisbon, and there is something weird with the 220v current. They have been experiencing come and go noises, and i could detect that Air conditioning and the coffee machine in the lobby make audio clicks in the control room.. Basically is whenever its thermostate relay works whether to open or close circuit.
They also have problems with tube outboards, like their LA2a, Retro compressor, UA 2-1176 and the brand new ADL 670...
Although im using only Wunder U47, into neve 1073 into ADL 670 atm for tracking vocals without any noise at all ive been told that tube gear should been avoided until they get someone to see what happens...
It seems the earth "Stick" is ok and the studio have its own, the voltage is 220V, one fase only i believe, and they said that measuring earth to neutral they had 0,4V. this shouldnt be a problem right?
They have alot of stuff like ups and i believe one "AC-DC-AC converter?" never heard of this one...
Can anyone explain me how to see if the power there is ok? what should i read besides voltages and frequency? is there things to avoid like UPS placement, shoud this be out of the control room?
Fixing the power as they say it need to be fixed? will this AC and coffee machine stop doing clicks? could this be "smoothed"?

ANy help is highly appreciated!
Cheers
Pedro Cruz

pedrocruz said:

They also have problems with tube outboards, like their LA2a, Retro compressor, UA 2-1176 and the brand new ADL 670...

Click to expand...

Have they actually narrowed it down that these units also have problems? Because maybe the real problem is something central like a mixer?

I'm asking because I had a similar clicking issue with our refrigerator where every audio unit I have is clicking really nasty. I was never able to solve it until I completely replaced and rebuilt my mixer PSU. Turned out the stock PSU was a really bad cheapo design with lowest quality parts and barely any protection. It was the only thing causing problems all along. Nowadays nothing clicks.

 I am sure that someone will pipe up with advice for suppressing clicks(fridges are the worst in my experience).



    I can help with the removal of clicks, farts, coughs, noise, hum etc from recorded material. Get yourself Izotope RX


   You will not regret it, I promise!


      ANdyP

Well this mixer is a SSL AWS900+se which is almost brand new and this shouldnt be a problem.

pedrocruz said:

Hello, ive been working in a studio here in Lisbon, and there is something weird with the 220v current. They have been experiencing come and go noises, and i could detect that Air conditioning and the coffee machine in the lobby make audio clicks in the control room.. Basically is whenever its thermostate relay works whether to open or close circuit.
They also have problems with tube outboards, like their LA2a, Retro compressor, UA 2-1176 and the brand new ADL 670...
Although im using only Wunder U47, into neve 1073 into ADL 670 atm for tracking vocals without any noise at all ive been told that tube gear should been avoided until they get someone to see what happens...
It seems the earth "Stick" is ok and the studio have its own, the voltage is 220V, one fase only i believe, and they said that measuring earth to neutral they had 0,4V. this shouldnt be a problem right?
They have alot of stuff like ups and i believe one "AC-DC-AC converter?" never heard of this one...
Can anyone explain me how to see if the power there is ok? what should i read besides voltages and frequency? is there things to avoid like UPS placement, shoud this be out of the control room?
Fixing the power as they say it need to be fixed? will this AC and coffee machine stop doing clicks? could this be "smoothed"?

ANy help is highly appreciated!
Cheers
Pedro Cruz

Click to expand...

If it is called a converter then it is possible that somebody botched something and it is not working. Normally a thing like that would be called a True On Line UPS. The mains AC is converted into DC and charges the battery. The DC from the battery is converted back to AC. A total isolation from the mains.  Ask them if it is a UPS and if it is, it is True On Line, not just On Line or worse, Line Interactive.

Mixer being brand new does not mean that it is immune from mains related contamination. Remember Falklands, HMS Sheffield? Despite the fact that it had the super duper EMI protected war gear, still two communication systems were interefering with each other. It's just that they made the mistake of shutting down one of the early warning comms and consequently got slapped by one of the exocets coming towards them.

First step to do is to have a dedicated mains line straight from the meter box serving only the audio equipment. Nothing else.

If the problem persists. The second step will be to swap the phase. Tap onto another one. If that does not help tap onto the third one.

If that does not help then the last resort is a possible but not very practical solution that would be to construct an LC filter using large electrolytics shunted by faster caps. But you'll need a heck of a bank of electrolytics and it is like having a time bomb. Need to be very well protected. I can confirm that it's been done before and solved the problem. I can not guarantee that it will solve yours though as on EMC you can only work on a case to case basis.

This may not be an easy solution for every situation, but for our (pretty small) studio, we had two ring mains fitted, one for the 'studio', and the other for all the other stuff - fridge, heaters, dehumidifier. I wired the sockets, and the electrician checked it and wired it back to the board.

Three years in and no problems (so long as you use the right sockets).

Ring wiring here in UK is obviously efficient in terms of wiring losses but at the same time can be a very bad news in creating hum.

When I came to the UK in '86 I could not understand why one would have such a strange wiring system, but later I learned that the practice dated back to wartime energy saving efforts.

sahib said:

... but later I learned that the practice dated back to wartime energy saving efforts.

Click to expand...

I didn't know that! Thanks! I think I had always assumed it was a safety thing.

Any overvoltage condition such as a spike will usually produce a tick in an audio circuit. Only the very best power supplies will really filter this out, and even they have no control of this if the tick is riding on an audio signal which is properly going through an amplifier. This could also be caused by a refrigerator motor or washing machine motor (on the same circuit) starting up. The higher impedance the entire chain of wiring is, the more likely this will happen and be noticed

in your case may be the coffee machine and hvac system.

The easiest way to prevent this from happening is to have 2 mains circuit feeding your studio. One should be strickly for all audio gear and the other should be for lights, random office equipment, computers, etc,etc.

  I think ideally, it is best to have all three phases, one for audio only, one for aircon, and one for fridge, cooker, kettle etc

strangeandbouncy said:

  I think ideally, it is best to have all three phases, one for audio only, one for aircon, and one for fridge, cooker, kettle etc

Click to expand...

+1

strangeandbouncy said:

 I think ideally, it is best to have all three phases, one for audio only, one for aircon, and one for fridge, cooker, kettle etc

Click to expand...

My apologies for being picky but being a spark by blood (my dad was an electrician) the correct distribution would be that all the switching appliances such as air con, fridges, coffee machines would be on one phase, lighting on the second and audio gear on the third one.

Obviously we are thinking of supplying the studio unit only, otherwise for an entire building one has to take even load distribution into account.

However, this is not all that easy. You will be running 3 phase side by side (unless you have seperate conduits) and one has to be exteremely careful. In a wiring environment like that the occupants would have to be trained not to carry out any wiring without the supervision of a qualified guy.

While at this I have just remembered a past experience. At one point we were getting a mega interference from the mains. I could not test our robot arms because both the servos and the micros would go haywire. It was that strong. It used to start around 4:00PM. It turned out that few blocks of flats were built down the road from us and they all had electric central heating. As a result as soon as the timers kicked in, the heaters were putting noise onto the mains. I swapped one of the phase and it went away.

lucky, they didnt swap the phase  too ;D

we use to use 3phase convertor box back in london.
it was about one cubic feet heavy metal box.
i dont remember the maker company, but it worked for us.

I was involved in an installation where a separate ring main was set up for the lighting, but it still interfered... The only option was to put the lighting on a variac - problem solved. Aircon and domestic appliances use similar triac networks to dimmers. Airborne, perhaps?

I find it pretty unusual to hear of a studio with an SSL that isn't on a dedicated ring main...

Justin

> Ring wiring here in UK ... I could not understand why one would have such a strange wiring system, but later I learned that the practice dated back to wartime energy saving efforts.

The energy savings is trivial, certainly not worth the re-wiring cost. 

The COPPER savings may be considerable. All loads on a floor use the same mains, unlike the US system where one bedroom may be idle and another one overloaded (it's been cold here, extra heaters). The cooker on the far end of the house has two paths back to the service, so each path may be half-size. Large loads may be connected anywhere, unlike me pulling fat dedicated stove-cooker cable through the joists, cable which is idle 99% of the time.

In war-time, copper is precious. Ammunition shells, factory upgrades, myriad of minor uses where nothing else will do such as electroplating base-coat.

Much as Aluminum was precious in WWII, so the US-built gliders, patrol boats, and the Spruce Goose were bent out of our abundant forests (over-abundant because domestic wood demand was slack).

I suspect that the real push to Ring Main was post-war rebuilding, many metals were in short supply for years (part of the Tucker story is access to metal). But probably fertilized by mid-war bomb repairs and ad-hoc housing when copper was tightly rationed.

Putting loads on different phases is a dubious technique. They all come from the same source, and normally over the same Neutral.

Serious cleanup suggests separate power transformer for audio and other. This breaks the neutral, and interposes two transformers plus a tap off the vast distribution network between coffeepot and console. That's horrendously expensive and may require interpretation of Electric Code and utility tariffs.

A lesser isolation is a 230V:230V(120V) isolation transformer just for audio. This breaks the neutral and adds some isolation from Mr Coffee. Some add electrostatic shielding for "tic" reduction. I'm looking at such a scheme to get furnace and pump surges off my Neutral. 2KVA costs $150 used/rusted $500 new/shiny, more for Famous Audio Brand. (An additional concern for me is that pump and furnace run maybe 5% of the total year, so standby loss costs are displeasing; not such an issue in a for-profit studio where the tranny may be turned off when customers and maintainers go home.)

PRR,

You are actually right. I just referred as energy savings effort but it was indeed due to shortage of precious metals. In fact here in Glasgow quite a majority of (Victorian) houses had their cast iron fences dismantled and used for the war supply.

I've found at least 2 ways pops, clicks, etc. can couple to audio circuits galvanically. One is simply voltage drop in the feeder wires supplying common circuits. This can make it's way through power supplies into audio circuits with low PSRR. The second is voltage drop in the neutral (grounded conductor) coupling into the ground reference. Measuring 0.4V earth to neutral may be a clue. I think it should be zero. Maybe pay close attention to where your earth and neutral are bonded together.

Perhaps a dedicated circuit with it's ground connected near the neutral bonding point is all you need, as long as all the audio grounds are connected to the same ground reference.

sahib said:

PRR,

You are actually right. I just referred as energy savings effort but it was indeed due to shortage of precious metals. In fact here in Glasgow quite a majority of (Victorian) houses had their cast iron fences dismantled and used for the war supply.

Click to expand...

My house (growing up in Liverpool) was similarly plundered. -Up and down the ENTIRE street, EVERY house had its railings removed and reclaimed for munitions and manufacture. -Not just my street, EVERY street in the parallel set of five streets, with about 120 houses per street.

COPPER savings is king, and yes, the US system (while lights dip annoyingly when you turn on a kettle or hair dryer)is MUCH better in terms of not producing anywhere NEAR so much hum.

However, the regs permit wiring 'spurs' from a ring, or home-run spurs from a fuse panel... If I were building in the UK again, that's how I'd do it.

Keith

i have to switch all appliances off when i record. my heating controller is one of them old bi-metal switch thingies, everytime the heating comes on i can actually hear the spark as the contact closes???

the 0,4 volt indicates  reactive current in the nuetral too many swtiched psu's???. id remove the ups sytems and check for noise again. i did some work in a data centre and checked V Outs on a scope and couldnt believe that the output from the Mega Buck UPS had more distortion/noise than the raw mains???!!

> the US system (while lights dip annoyingly when you turn on a kettle or hair dryer)

Doesn't have to. Really shouldn't. I have a table by my fusebox which tells how far a wire can go with <2% voltage drop.

But anything more than one 16'x24' floor, you gonna have a few runs which "should" be up-gauged. However inspectors rarely question small over-runs and and buyers don't have the clue.

Many Florida houses must have quuite long runs.

My school ran 20A circuits halfway around the building, on #12 wire, which won't burn, but gives about 13V drop at full load.

I could see when the coffee pot was cycling in the lights, but not by clicks in the audio. There's another factor in Pedro's case.

> However, the {UK} regs permit wiring 'spurs' from a ring, or home-run spurs from a fuse panel

Of course, probably. Spurs are often necessary. Homeruns are often useful. (Consider a small residence with an electric pottery kiln, or a pot-farm.) The general-use ring-main is just about COST. And given a lower-cost technique, no UK electrician will run your homeruns without explicit instructions, extra payment, and maybe close supervision.

I'm not clear why ring-mains would hum more?