Buzzing noise with new SM57 through PA...

Hendrix89

Hi, i asked for help on this on another forum but I think its best to have a second set of opinions so anyway ill explain.

Ive just started getting an annoying buzz/hum noise when I put my new sm57 through my PA system and i need to know whats causing it and if its my mic. The noise is very similar to what you get with single coil pickups. The buzzing isnt constant, it lessens/worsens when i move the mic. When i try my other (cheaper) mic through the PA i get no interference at all so could it be my mic? I have taken really good care of it and i only bought it a week ago so its hard to believe...

Soundman

Sounds like it is picking up interference from an electrical source somewhere in your rig. The cheaper mic might not pick it up due to lesser quality components. Could be an earth problem, being too many earths in the system or even not enough earths.

Hendrix89

Hmm okay is this a common problem? I have done all I can to stop or reduce the noise and haven't gotten very far, although when I switched all the lights off and computer/monitor the noise reduced quite a bit but was still there. Also as a test I put my mic into a guitar amp and got no sound (as in voice) at all...

I haven't got a recording interface/preamp yet but will have a Firebox soon, will i have the same problem (buzz) or is it unlikely?

Soundman

It does sound like interference from something electrical now alright. I have done gigs before where we have had to turn off all dimmable lights in the pub/club as we would constantly get buzzes through things.

What did you use to put it through your guitar amp? Which microphone did you try it with?

I can't say for sure but it is possible that the problem will continue even with your pre-amp/interface.

Hendrix89

Soundman wrote:

It does sound like interference from something electrical now alright. I have done gigs before where we have had to turn off all dimmable lights in the pub/club as we would constantly get buzzes through things.

What did you use to put it through your guitar amp? Which microphone did you try it with?

I can't say for sure but it is possible that the problem will continue even with your pre-amp/interface.

''What did you use to put it through your guitar amp? Which microphone did you try it with?''

The one that im concerned about (sm57). Just put it straight in. Well I also tried my other mic (JTS) into the guitar amp and it worked so that kinda worries me. Remember both mic's work through the PA. Its the SM57 which buzzes through it. Any idea?

Oh yeah forget to mention, I was using the SM57 to mic my guitar amp today and I wasn't getting much buzz at all. Actually it was barely audiable... Strange...

Niall - Dahlia

Well you say the buzz increases/decreases as you move it around the room...so what are you moving away from to decrease the hum? You have a PC in the room right? I imagine that might be the culprit.

Is your XLR cable new/in decent shape? Do you have electrical cables on the floor crossing your mic line?

Hendrix89

Niall - Dahlia wrote:

Well you say the buzz increases/decreases as you move it around the room...so what are you moving away from to decrease the hum? You have a PC in the room right? I imagine that might be the culprit.

Is your XLR cable new/in decent shape? Do you have electrical cables on the floor crossing your mic line?

Em well its hard to say, it changes all the time. Yes I have a PC in the room but I have tried turning it off and the buzz did not go away completely, however it did reduce a fair bit.

''Is your XLR cable new/in decent shape? Do you have electrical cables on the floor crossing your mic line?''
Well the cable is just new (planet waves classic series xlr-xlr), I will be exchanging it for a much better quality one though so that might help. I will be getting the custom series one which looks much better. Not much cables around the mic line, there is a keyboard and an amp near the PA though (which of course have cables) if that would be enough...

COOKSTER

There's a lot of variables that can cause a "buzz" and as we all know these are hard to solve unless one is able to eliminate what's NOT causing the problem.
1. Turn off all other amps and lights, plug them out too cause there may still be juice running into power transformers. Does the problem drop significantly when you turn off a particular unit/light?
2. How many mics/lines are connected to the mixer
3. without changing any settings, mute all but the 57 and another vocal mic, If there is still a bad noise, mute the 57, if the noise drops then the fault is definitely with the 57 signal path (mic, lead, mixer settings). You can then change the 57 for a different mic to see if the problem goes away? If not change the lead, any better?
4. you say that when you tried it on your guitar amp the noise wasn't so bad. Is it possible that you are introducing noise into the mic path for vocals by having Power amp/master/channel fader levels too low, and channel GAIN too high, thus bringing up the noise floor of the signal path.
5. it is possible that the earth (pin 1) is disconnected in the mic barrel, or in the mic lead, check also the earth connections in all plugs (especially extension leads).
Genuine shure SM57's shouldn't introduce hum by themselves into a signal path. They are made to be crammed right into the face of blaring guitar speakers. What brand is your mixing desk/ power amplifier? Are you a strong singer/ is backline very loud? These might be indicators of reasons why noise might be increased. Even answering all these questions thoroughly may not solve your problem.
All the best
C

Hendrix89

COOKSTER,

Yeah I have tried most of those. None made much of a difference except for the lights and computer. When I switched them off there was a noticable reduction in the noise.

''4. you say that when you tried it on your guitar amp the noise wasn't so bad.''
Actually (i dont think i was clear) the sm57 didnt work at all in the amp, as in no sound at all came through. Im a bit worried about that.

''Genuine shure SM57's shouldn't introduce hum by themselves into a signal path. They are made to be crammed right into the face of blaring guitar speakers. What brand is your mixing desk/ power amplifier?''
Thats what concerns me, i mean this is the last mic i'd expect this from... The brand of my PA system is Carlsbro. I guess its low to mid range.

COOKSTER

If you don't have the problem with other mics then it's just your mic.
Is it a genuine SM57? Did you buy it from china on ebay?
The earth might be disconnected inside, though I would be surprised with a new mic. If you wish to check, plug out the mic. At the base of the mic is a small hole with a screw inside. It is reverse threaded, so turn it anticlockwise to open and the screw will recede inside the mic, once it has cleared the casing, use a small pliers to remove the base, gently, you don't want to disconnect the cables inside. Make sure there is a silver link wire from pin 1 to the silver metal band, this band should make contact with the body of the mic when inserted. If no link wire bring the mic back to where you bought it and ask for a repair or replacement.

Don't worry about the mic not working when plugged into your guitar amp, it's a "guitar" amp after all!!! (again too many variables, lead wiring, pre-amp circuitry, input used, etc).

Again, I stress checking the earth wiring in the plugs on kettle lead and extension lead used to power Carlsbro mixer. (green/yellow wire to top pin, if you are not sure get an electrician or other qualified person to check it out, if this is faulty someone could die)

If it's lights that are causing the problem, try rotating the mic through 360 degrees (full circle) while holding it horizontal, the buzz should have 2 strong points and 2 weak points, you'll just have to place your mic on a weak axis.

No harm changing the mic lead too.

Does the PC introduce noise in the system with or without an audio connection between the PC and mixer. you may need to use DI boxes or isolating transformers to isolate the PC power supply from the mixer audio path.

It is a process of elimination,m so be patient and try one thing at a time.

C

Hendrix89

Alright I just tried it in a studio and it sounded bloody fine! No buzzing at all!? Im still here now. So what does this mean?

frobisher

Do you have any lights on a dimmer switch running in the same room as your gear? Dimmers are an absolute killer for this kind of thing.
Other than that and the problems with earthing that cookster went over, you might have a faulty mic.
Let us know how you get on.

Hendrix89

Hi. Well things have been going alright actually. My Firebox arrived a couple of days ago and ive been able to get a nice clear signal through the mic. YES there are four dimmer lights in the room i use for recording and they were definately causing it as I did some tests. I recorded a couple of seconds with the lights on and there was noticable buzzing. Then when i turned the lights off there was not a sound! I usually record in the day so that works out fine. Also i did buy a very high quality mic lead (ahem.. 36eu..) so that may be helping too but im absolutely certain it was the lights. They even make a small buzzing sound whenever i turn them on! Wait so do you still think my mic is faulty? I mean should it not be picking this up in the first place?

frobisher

Dimmer lights can cause this and probably it has nothing to do with a fault in your mic. One of the things to watch with dimmers is that having them turned on a tiny bit is usually worse than having them on all the way, so don't be fooled by thinking you'll just barely have them on!

Soundman

Soundman wrote:

It does sound like interference from something electrical now alright. I have done gigs before where we have had to turn off all dimmable lights in the pub/club as we would constantly get buzzes through things.

*cough*

Hendrix89

''It does sound like interference from something electrical now alright. I have done gigs before where we have had to turn off all dimmable lights in the pub/club as we would constantly get buzzes through things.''

Soundman wrote:

*cough*

Oh sorry Soundman lol credit to you :-) Yeah well now I know theres definately, definately nothin wrong with my mic! Thanks for the first hand info Soundman. Sorry again for overlooking ;-)