Noise

ibenko · Post by **ibenko** » Wed Jun 02, 2004 6:07 pm

Hi all!

I need some help again. I noticed that there is really noticeable noise coming out of all equipment that is plugged into wall outlet. My battery Minidisc makes almost no noise. I also noticed that there's no noticeable noise coming from sony radio (the little one) but this one is plugged into wall outlet,so how come this shitty radio doesn't do any noise, but all the other almost proffesional equipment does.

I made recording of noise and amplified it:
http://users.volja.net/ibenko/noise.mp3
First one is comming from my Behringer MIC2200 but its the same on kurzweil k2000, yamaha psr630, nec cd player. The second one is from my mini disc player (battery operated).

Can someone please help me, would UPS help in any way, to stabilize electricity?

Sorry for my bad english.

Tny in advance!

Best regards, Igor Benko

at0m · Post by **at0m** » Wed Jun 02, 2004 6:47 pm

Have you tried out blazesboylan's tips?

ibenko · Post by **ibenko** » Wed Jun 02, 2004 7:48 pm

He he :> :>

I tried it, but in my case this happens with the same f***ing cable :> So what to do?

Best regards, Igor

Post by **garyb** » Wed Jun 02, 2004 9:06 pm

i'd have an electrician check phase and ground on your ac line.

a ups might help if it does line conditioning. most likely, there is a wiring problem.

you might try making sure all elements in the signal chain are pligged into the same outlet or at least the same breaker. you may also be able to lift grounds either on the signal end if using balanced lines or on the ac end, but beware of ungrounding everything,that practice can lead to electrocution...the pc should stay grounded. the mixer or micpre probably should be grounded as well for safety, but at least the pc should use all three prongs.

ibenko · Post by **ibenko** » Thu Jun 03, 2004 2:00 pm

Hi!

I just cut ground wire and the problem has gotten away, but I anyway would like to have grounded equipment. Is there any way to connect the ground cable somewhere else?

Would this help?
http://www.furmansound.com/pro/pwr_cond ... es%202.htm

Best regards, Igor

BingoTheClowno · Post by **BingoTheClowno** » Thu Jun 03, 2004 2:19 pm

Do you live in a house or appartament building?

If you live in an appartament building try connecting a wire from a screw on your PC metalic case to a heating radiator if you have them. Or try connecting the metal cases of all of your electronic devices together.

If you live in a house, you can create a ground plane by driving couple of galvanized pipes into the ground and connecting them together.

See if you shut off your monitor if the noise disappears. If you use a mixer, check for slight feedback, turn off all inputs one by one and see if you find the one that generates noise.

[ This Message was edited by: BingoTheClowno on 2004-06-03 15:22 ]

ibenko · Post by **ibenko** » Thu Jun 03, 2004 5:57 pm

Hi!

I live in a house. I tried both advices you gave for appartment situation, none of them worked. I didn't really understood that advice for house, could you explain more like for dummies and those who don't understand english to well

Monitor doesn't affect sound in any way, I have only behringer mic2200, both channels are alright, I get this noise even with device turned off.

Could power conditioner help in this situation?

Best regards, Igor

astroman · Post by **astroman** » Thu Jun 03, 2004 7:00 pm

the power conditioner could have an influence, but it cannot be guaranteed - the unit you mention doesn't look cheapo.

On the other hand it could save the day and possibly some more if something happens to main powersupply - not too long ago someone had a fried PC due to a failure which peeked way beyond regular voltage.
Depends of course on local supply, thunderstorm probability etc.

You should really get the house checked if it's grounded properly.
While it is hazardous for obvious reasons, an ungrounded electrical supply acts completely wiered.
In fact - if you followed all good advices and it still reacts unexplainable - that's a good indicator the house isn't grounded.

At my parent's home they found this out after 20 years when a new heating was installed.
But right before that my dad asked for an advice regarding his video recorder, which had an error as if the tape didn't settle properly when started.
This changed when modifying the position in the antenna daisy chain.
The error was reproducable, but impossible to explain - and you'd swear it had a mechanical source.
I finally ended with the infamous sentence: '... then you have a ground problem...'

cheers, Tom

[ This Message was edited by: astroman on 2004-06-03 20:03 ]

Post by **hubird** » Thu Jun 03, 2004 8:56 pm

Post by **garyb** » Thu Jun 03, 2004 10:01 pm

also, you should NOT cut ground plugs when there are adaptors available. what line did you cut? if you cut on one device you are likely still grounded through another in the chain. as i said, for safety i wouldn't cut ground on the pc or on the mixer(if you have one) but anything else is pretty much fair game. multiple grounds on devices that have the signal ground connected to the chassis ground are likely to cause ground loops so i'm not surprised that what you did worked. it is the same principle that causes ground-lift switches to be installed in better gear...

*edit* NOT cut..NOT cut.... duhhh

[ This Message was edited by: garyb on 2004-06-04 04:47 ]

bassdude · Post by **bassdude** » Fri Jun 04, 2004 3:36 am

We are not going around lifting ground on power cords again are we? I hope not. It is much safer lifting ground on the interconnecting signal cables. Go here:-

http://www.rane.com/note110.html

*Never* cut the ground pin on a power cable for equipment that requires earthing. It is extremely dangerous especially if you have a bodgy earthed house in the first place.

Best advice is to unplug everything, add each unit back into the signal chain until you find the culprit, then lift the *signal* ground if required.

BTW, that doesn't sound like a ground loop problem to me. More like a lack of proper earth.

Goodluck!

blazesboylan · Post by **blazesboylan** » Fri Jun 04, 2004 3:58 am

Hi Igor.

GaryB's suggestion (lift ground) is a good one *but* be very careful... I suspect you're lifting ground on the mic pre? Then do NOT use a mic (or guitar etc) with that mic pre!

(I've learned the hard way to make sure I don't touch anything that isn't grounded.

)

If you have a ground loop there are a few ways of dealing with it. There are a few different "ground" channels for any given audio device:

Audio ground: this is the reference point against which unbalanced signals' amplitudes are measured.
Earth ground: this is the 3rd prong in your AC power cord.
Chassis ground: the metal casing on your device is a ground channel, too!

The signal ground and the earth (AC power) ground usually provide you with the "ground loop":

Code: Select all

  Device 1  <----signal ground---> Device 2
      |        (via audio cable)       |
     _|_                              _|_
     |||                              |||
   Wall outlet <-------------> Wall outlet

This loop antenna picks up noise from left, right and centre, and the noise signal is carried by the audio ground channel. When you measure your audio signal against it, your measurement fluctuates with the noise.

Code: Select all

Non-noisy ground channel:

  ________________

Noisy ground channel:

  ////////

So if you're getting a ground loop here, Igor, then you need to cut the loop. What GaryB suggested is the following:

Code: Select all

  Device 1  <----signal ground---> Device 2
      |        (via audio cable)       |
     _|_                              _|_
     | |                              |||
   Wall outlet                   Wall outlet
 (not earth-grounded)        (earth-grounded)

There are a few safer techniques for eliminating ground loops:

Single-point grounding (common for recording studios)
Multiple-point grounding
Floating connections
Telescoping shields (I think this is the technique GaryB suggested)

The basic idea in single-point grounding is that you only have the audio ground connected to earth (and chassis) ground at one single point. I've never actually done this. If anyone has, I would greatly appreciate hearing how you went about doing it.

If you decide to pursue the ground loop elimination route, be prepared for a slog. It's not simple stuff. Sound Reinforcement Handbook is a good book for discussion of proper grounding techniques. You should also be able to find online articles that cover the same material. (Do a search with Google.)

Having said all that...

BingoTheClownO's idea of grounding the computer via radiator / plumbing pipes / etc is an interesting one

, but... If you lift the ground on a particular device, and then connect its chassis to a radiator / plumbing pipe, you *may* be grounding the device properly (i.e. avoiding shock) and you certainly will eliminate the ground loop. But on the other hand, are you really sure your device is grounded?...

Attaching all the chassis of your devices together would presumably introduce *more* potential for ground loops. I'm certainly not an expert at this stuff though, so I may be missing the point?

Code: Select all

      _________ chassis ground _________
      |                                |
      V                                V
  Device 1  <----signal ground---> Device 2
      |        (via audio cable)       |
     _|_                              _|_
     |||                              |||
   Wall outlet <-------------> Wall outlet

I read the bit about the Furman power conditioners. Now traditionally a power conditioner is meant to prevent your gear from frying when you get a power surge (because of lightning or whatever else). Sometimes they'll also regulate voltage, to clamp it to (for example) 105-115 volts, even if the input from the wall outlet drops to 90 volts or pushes up to 130 volts.

The music-specific power conditioners you cited do also apparently eliminate a substantial amount of noise, by using some kind of filtering magic.

Specs are always misleading

, but if those conditioners really do eliminate 10 dB of RFI noise in the normal audio spectrum < 10 KHz (who cares about 1 MHz) then that means they're cutting the noise by about 3 times.

Here are a few things to check:

Are the chassis of your devices touching? Are they in a metal rack? Try separating them, so that they don't touch each other.
Try to isolate the problem. Deal with 2 devices at a time (for example, your computer / Luna 2496. and the mic pre) and keep adding devices one-by-one until you get noise. Try starting with a different pair (e.g. Computer and K2000) and see if you get the same results. This may give you extra clues.
Keep amplifiers and lights well away from your other audio gear. Power supplies (for example, for mixers) can be noisy too. Don't use lights with dimmers! Don't use fluorescent lights!
Make sure your cable isn't the source of the problem. Behringer makes a cable tester that is cheap but works very well (as long as you keep the batteries fresh...). If you have corrosion at the connections, or a bad solder job, or a slice in the cable, you'll get noise by moving the cable. If the noise is constant even when you're moving the cable, then the cable is definitely *not* the source of the problem.
Bring in the electrician! (See GaryB and Astroman's posts.)

Now my experience with noise is very particular. I have certainly not dealt with it enough to know exactly what you're encountering here. But if I had to hazard a guess, I would say that the MP3 you posted sounds to me more like interference from a light (such as a fluorescent light or a light with a dimmer switch) than your traditional ground loop.

In fact I may be completely out to lunch here, because I don't think I've ever even heard ground loop hum. (Maybe this is because I'm using the Furman PL-8?!?!? I didn't even know it had any filtering until you pointed it out!) I *have* heard radio stations from Seattle loud and clear -- that is how ground loops have manifested themselves in my studio. Not at all like your MP3.

I have, however, heard lots of other noise sources (monitors, cell phones, lights, fans, power supplies, etc) that produce buzzing very similar to your MP3.

So just make sure you carefully check all the other electronics that might be affecting your audio gear. Turn them all off and see whether the noise goes away. Even if I'm way off base, it'll be worth it, in the end, to be thorough.

Good luck with it Igor! Keep us posted on your progress, eh?

Cheers,

Johann

ibenko · Post by **ibenko** » Mon Jun 28, 2004 8:54 am

I finnaly took some time to figure out what's making this noise. I guess only computer itself is producing noise. Using only computer, behringer mic2200 and not grounded sony amplifier I get noise, if I groundlift behringer the problem is gone. What can I do about computer?

Tnx in advance, you are really the best group!

Best regards, Igor

[ This Message was edited by: ibenko on 2004-06-28 09:55 ]

Post by **garyb** » Mon Jun 28, 2004 12:06 pm

the behringer stuff is not well shielded(the price of cheap stuff). you'll have to experiment with using different sockets. also, you may need an electrician. if you are using balanced cables, you may be able to lift the ground on one end....

Stige · Post by **Stige** » Mon Jun 28, 2004 12:12 pm

I had similar problem between computer and mic pre. When I put a thick wire from mic pre case to computer case, thus connecting their grounds together, the noise went away.

ChrisWerner · Post by **ChrisWerner** » Mon Jun 28, 2004 12:33 pm

Same here, I have noise in "quite" mode in the array of 0 up to 60+ Hz, around -60dB.
But I don´t care when the voice, music or whatever come over, I don´t hear it.

... all vents, graphic card, mouse movements, tranfers from HD etc. are cause noise in your system. The best solution would be to shield your cards toward the other areas of your computer.

But I can´t tell you how....

[ This Message was edited by: ChrisWerner on 2004-06-28 13:42 ]

blazesboylan · Post by **blazesboylan** » Mon Jun 28, 2004 4:33 pm

On 2004-06-28 13:33, ChrisWerner wrote:
Same here, I have noise in "quite" mode in the array of 0 up to 60+ Hz, around -60dB.

This is most definitely a ground loop. What's the AC frequency in Germany? Is it same as UK (50 Hz) or US (60 Hz)? If the noise is constant and always the same frequency ~50/60 Hz then it is ground loop hum. Getting rid of ground loops is a royal pain in the derriere, but I would start by switching to balanced cables.

Incidentally a lazy man's approach

would be to put a noise gate or an expander on your input signal at about -50 dB with 1:4 ratio (for example), to filter out the hum.

A slightly more effective reduction would be: a notch filter at 50/60 Hz, followed by the noise gate / expander.

Igor: try without the amplifier. The impedances are mismatched, but you can still plug a pair of headphones directly into the Pulsar Analog Out. If the amp was causing the problem, you won't hear any noise through just headphones. If the amp was not causing the problem you should still be able to hear noise through the headphones.

If you still hear noise, remove the Behringer unit. Run a plugin (e.g. Control Room with a sine wave output) out to the Analog Out.

If you still have noise, the computer is the source. But from the sounds of it I would suspect the Behringer or the amp. If the amplifier is introducing hum, and if the audio ground signals are all connected (99.9999% of the time this is the case), it could very well be the amp.

I seriously doubt it's the computer. By the time power gets to the audio card, it's been through a big transformer to turn it into DC. I can't imagine how ground loop hum could be generated by an audio card...? There could be a bad solder job or corrosion at the Pulsar connectors but these would generally cause very loud intermittent crackling.

Anyway if the problem is ground loop hum then it ain't coming from the computer. I still have my doubts that it is a ground loop, and looking back it seems BassDude does, too. But who knows...

Chris Werner does have a very good point -- keep the Pulsar cards as far away from fans and HDs as possible.

The following questions are probably irrelevant but just in case:

What mic (or line input?) are you sending into the MIC2200?
What make + model of amp are you using?

Cheers,

Johann

ibenko · Post by **ibenko** » Tue Jun 29, 2004 5:34 pm

I again spent one hour finding the source of problem and I still guess that computer is main actor by producing it. I was using battery operated minidisc recorder for headphone amplification, behringer mic2200 mic preamp, kurzweil k2000, grounded nec scsi cd rom with audio output and computer with luna breakout box. My observations:
-when I connect scsi cdrom -> preamp -> md I get noise only when the computer is powered on, I thought this might be because the cdrom is put on top of the computer (but it isn't connected by any way to the computer)
- kurzweil k2000 -> preamp -> md doesn't cause any noise, maybe a bit of hum, but this isn't noticeable
- k2000 produces that bad noise when directly connected to luna, scsi cd rom and and behringer preamp are making the same noise when used with luna

I guess interior placement of cards doesn't affect in any way the sound because I am using luna breakout box so everything comes digitally into computer. Could there be something wrong with my computer power supply? I don't know what would it help to use balanced lines, luna box doesn't offer any balanced inputs and I'm using only 1 meter long cables. This is kind of driving me crazy I only wish there would be easier solution but I guess this is kind of big problem.

Johann: no matter what signal I'm sending into preamp everything is the same, even with nothing plugged in. I am using sony hifi amplifier that isn't grounded and I get same results by just using battery operated md recorder.

Tnx for your great help!

Best regards, Igor

Post by **garyb** » Tue Jun 29, 2004 9:52 pm

could be the power supply..(low voltage?)..

are you sure your mains are wired properly/correct voltage?

[ This Message was edited by: garyb on 2004-06-29 22:53 ]

blazesboylan · Post by **blazesboylan** » Tue Jun 29, 2004 11:32 pm

Edit: Sorry, Igor, I didn't read carefully enough before I posted this. I didn't see that your CD->preamp->MD combo caused the same noise, but only when your computer is on. Of course this is a vital piece of info, so

. You can safely ignore my whole original post.

When you turn your computer on, do you turn your monitor on too? Try leaving it off...

Otherwise I'll have to finally concede and say: Yup, must be the mains. Call the electrician!

(Sorry for taking so long to come 'round.

)

Good luck Igor,

Johann

On 2004-06-29 22:52, garyb wrote:
could be the power supply..(low voltage?)..

are you sure your mains are wired properly/correct voltage?

Hrrrmmmmm hooommmm... The Luna 2496 box is powered by the PCI bus. There is no external wall wart for it. So you may very well be on to something GaryB (low voltage). I have no idea how that would sound, personally.

But since the mic pre, amp, K2000 and so on seem to work fine, I would do a bit more investigating before blaming the mains. Who knows though...

Anyway, as GaryB points out, after a while PC power supplies do eventually lose their "push". If you have (or can get access to) a multimeter, Igor, you can check the voltage coming out of the PC power supply yourself. Make sure you read the multimeter manual carefully.

Since you're dealing with low voltages it's pretty safe stuff. However stay away from the actual PSU -- just deal with the multi-coloured disk drive connectors.

Each disk drive connector is wired in a standard way, so those connectors are the best indicators IMO if you're going to try to figure out whether there's a voltage problem inside the computer.

The yellow cable is +12 V (these power the fans in the computer, as well as hard drive fans);
The red cable is +5 V (for the chips)
Each of the 2 blacks is the ground corresponding to its neighbouring colour.

So with your multimeter reading DC voltage, stick the black ("common") probe into the black (ground) pin (beside yellow) on an unused disk drive connector cable. Then stick the multimeter red probe into the yellow (+12 V) pin.

With these voltages you won't get hurt mixing up the order. But it's good practice to always contact ground first. Otherwise you become the path of least resistance to ground!

Repeat the process for the black ground / red (+5 V) pins.

Now I dunno how PCI works. GaryB / Astroman / et al., does PCI send just 5V to cards? Or does it send a current with 12V too? Or...?

Unfortunately the Scope manual doesn't specify what voltage the Luna 2496 requires. My guess would be 5V, but that's a pretty uneducated guess.

Whatever the case, the multimeter test will let you know if your voltage is really wonky. I don't know what it would make gear sound like, I've never heard the result. But a really old PC power supply can push through as little as +8V and +3.5V (rather than +12 and +5).

Also Igor have you tried sending the K2000 directly to the Luna II card's analog input? (I'm assuming it's a Luna II card that you're using with the 2496?) Because there are still 2 other possibilities:

the Luna 2496 has a problem; and
the FireWire cable is faulty or not contacting properly at one end or the other.

If the analog ins/outs of the CreamWare card work without noise, that would at least narrow the problem down to the 2496 and / or its cable.

Anyway sorry for the myriad tests

but unfortunately I suspect that testing, testing, testing is the only way you'll get to the bottom of the mystery.

Good luck Igor + ciao for now,

Johann

[ This Message was edited by: blazesboylan on 2004-06-30 00:50 ]