# My brand new expensive microphone keeps on giving off static whilst recording



## Syd Justice (Dec 4, 2011)

Basically i just bought an expensive microphone that just keeps giving off static during playback. Even when i dont say anything and just press record. I managed to improve the sound by going to control panel-hardware & sound-manage audio devices- Recording-microphone (advanced)- 16 bit studio quality setting. Is there anymore i can do? or is it the wires from my stereo microphone pre-amp ausing the static. I tested the microphone in the store on a DJ set and it seem fine, so i know its not the mic. Please help, cheers


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## Syd Justice (Dec 4, 2011)

oh yes an i am using windows 7


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## dai (Jul 2, 2004)

is it static or feedback


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## Syd Justice (Dec 4, 2011)

Its definately static. i tried downloading sigmatel audio driver to no avail


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## dai (Jul 2, 2004)

see if this helps

http://www.techsupportforum.com/for...rfering-with-your-music-enjoyment-145516.html


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## Fred Garvin (Sep 4, 2010)

What kind of mic and pre-amp and how are they wired? XLR, Hi/Low impedance etc? Any change if you bring down the mic gain at the preamp?


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## niemiro (Feb 20, 2010)

Syd Justice said:


> Basically i just bought an expensive microphone that just keeps giving off static during playback. Even when i dont say anything and just press record. I managed to improve the sound by going to control panel-hardware & sound-manage audio devices- Recording-microphone (advanced)- 16 bit studio quality setting. Is there anymore i can do? or is it the wires from my stereo microphone pre-amp ausing the static. I tested the microphone in the store on a DJ set and it seem fine, so i know its not the mic. Please help, cheers


Hello!

Can you please tell me exactly what setup you have (microphone wise), and in particular, what microphone you just bought.

By the sounds of it, your mic is experiencing something called self noise, where it picks up the sound of air movement, and just about every tiny motion and noise in your room. This is very common. The more you amplify your mic, the louder it will get.

Basically, there are three main types of microphone: Dynamic, condenser, and ribbon. 

Dynamic mics are the most robust, and work just about anywhere. They are perfect for the home studio, very tough and versatile, cheap, and can be used on just about anything. They do not require Phantom Power. A cheap desk microphone (I do NOT recommend) have a tiny, cheap, dynamic mic in them. A popular example is the Shure SM57/58.

Condenser microphones are extremely sensitive. They will pick up every tiny sound, and are prone to self noise (what you are experiencing). These only really work in a properly sound conditioned studio, or prehaps a sound conditioned DJ shop. Without a properly sound conditioned room, you will just get lots of self noise, and it can ruin your recording. These require Phantom Power, and are much more delicate. Also, you MUST use a pop filter (either nylon or metal is fine). Can I recommend that you buy a pop filter, because pop filters made of tights may be cheap, but they are utterly useless, and not comparable to the real thing.

Ribbon mics are N/R.

By the sounds of it, you have bought a condenser mic, and you would have been better off with a dynamic mic. Dynamic mics are not cheap rubbish. They are EXCELLENT for certain types of recording (although condenser mics are better at other types of recording, specialised, specific types of recording, general purpse home studio, PA system, vocals, guitar box, etc. etc. will be just fine on a dynamic like a Shure SM57. Do not rule out dynamic as useless). President Barack Obama's [EDIT]Apparently, every president since Lyndon Johnson have used a pair of SM57s. I didn't know that...[/EDIT] sound team use a pair of Shure SM57 with a pair of A2WS windscreens to amplify his speeches every time. Look it up if you don't believe me ) If you intend to do vocals on a dynamic mic, I would, again, recommend a windscreen, despite a common misconception that they don't need them - they just don't need them as much 

Please let me know which mic you have, and I may be able to help you further. Obviously, you may consult with me before you take anything back, but if changing your mic is absolutely out of the question, here are some tips.

Firstly, the more you amplify your mic, the louder and more obtrusive the self noise gets. Most tactics revolve around reducing amplification. 

* Sit closer to the mic - make your voise louder relative to the self noise. If you are recording an instrument, place it closer. For overheads, or wide pickups, you are going to have a problem.
* Note the pattern type of your mic (omni, super/hyper cardioid, figure 8, etc.) and use it to sit in the right place. The looser the pattern, the more prone to self noise it will be. 
* To allow you to sit closer without being affected so much by plosive sounds, use a good pop filter.
* Try to improve your room, change room, use wall drapes, etc. etc.

If you can give me some more specifics, such as how you intend to use the mic, what mic and setup you have, etc. etc., I may be able to help you more.

Richard


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## Syd Justice (Dec 4, 2011)

i am using an AKG acoustics dynamic microphone D77 S/XLR. Crystal clear sound series microphone. i plugged it to a stereo phono preamplifier (SP-24B). Basically the pre-amp is connected to the power source, then the mic is connected to the pre-amp. then the preamp is connected to the pc. I wasted my money getting a much more expensive shure mic just to encounter the same problem, i took it back but only got credit to buy something else in the store, bummer. Whats annoying is that the vocals are good but there is static. i have got lots of wires in my room and my roon is quite small so i might try taking it out and see what happens. Thanks for the feedback so far


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## Syd Justice (Dec 4, 2011)

i just read about m-audio duo and edirol soundcards. But they are expensive


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## Fred Garvin (Sep 4, 2010)

At first glance it looks like you have an impedance mismatch between the mic and preamp, which will make the signal more susceptible to interference. If the mic cable you have goes from XLR to 1/4" (TS), then it's unbalanced. If it's a 1/4" TRS (2 black lines on the tip, it's balanced. I can tell by looking at a picture of the preamp that it's a cheap one and most likely doesn't use a balanced signal. You could try a transformer on the preamp input side and see if the static stops, but that's kind of a fudge it fix.


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## Syd Justice (Dec 4, 2011)

ok thanks, i will try it


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## jaythorpe522 (Sep 7, 2010)

Any way to hear a recording of this "static"? Would help us identify the problem. Before buying any other piece of gear, unplug the mic and see if this 'static' is still there. I would put my money on that cheapo pre-amp box being the sole source of the problem.

What is your computer's audio input? Do you even need that box? The self-noise added by the computer's gain might not be as bad as using that box.

If your cable is TRS, there's a possibility (small) that the box isn't even shorting the sleeve and the ring -- there could be a single point of contact on one or the other. This could severely increase susceptibility to RF interference. Getting a cable that makes the short (TS) or shorting it yourself might help. Also to cut down on RF, run the mic cable as straight as possible, and keep it clear from AC power (especially coiled AC cables).

DO NOT get an impedance matching transformer. Matching impedance from mic to pre _LOWERS_ signal to noise ratio (this is bad). Pre input impedance should be on the order of 10x the mic's output impedance. The D77s's output Z is 600 Ohms, the SP24b input is 10kOhm, so it's 'in the right ballpark' for optimal voltage transfer (the signal you are transferring is variation in voltage, there is no current transfer necessary).

Tell us your computer soundcard specs and, if possible, let us hear the static and we'll get those smooth vocals layed down...

jw


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## Fred Garvin (Sep 4, 2010)

jaythorpe522 said:


> DO NOT get an impedance matching transformer.


This is incorrect. In pro audio, you just don't mix and match hi and low signals w/o the use of something like a DI box or a transformer. The preamp mentioned above and the average computer sound card are high impedance, consumer level products. Anything that uses an RCA connector is not pro audio and they do not use the same signal level as a Low-Z mic. The end result signal in the case above is already sending a hi impedance signal into the sound card. The transformer just matches the signal between the mic & preamp.

Transformers - When should you use one?


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## jaythorpe522 (Sep 7, 2010)

Fred, I'm sorry, but you are mistaken. In early days of Pro-Audio, you matched mic impedance with your tube preamps. But that was long ago, and we're in the transistor age. The voltage differential signal is what must be passed with highest clarity. Voltage level at the preamp is Source Voltage multiplied by [preamp impedance / (mic impedance + preamp impedance)]. That's ugly, try this:

Vp=Vs*[Rp/(Rm+Rp)] // (V is voltage, R is impedence/resistance)

Obviously, the lower the Rp, or the higher the Rm, the lower the Vp with a constant Vs. With a lower Vp all around, the variation of Vs will be a less significant figure, which translates into a lower signal to noise ratio and a higher noise floor.

Unless the impedance matching transformer is itself a powered preamp circuit, it raises Rm without raising Vs and, as I said, DO NOT get an impedance matching transformer because it will lower your signal to noise ratio (This is BAD).

Also, I think you meant 'line' level -- there is no such thing as 'consumer level', tho' there are different standards for line level, i.e. consumer (-10dBV) and pro (+4dBu in US, +6 in Europe). At any rate, the preamp is designed to take a mic-level input. Input impedance of 1-2kOhms is standard for preamps and other boxes taking a 'professional' lo-z microphone level of around 100 Ohms. The D77s is a 600 Ohm output impedance mic, mid-Z, and 10kOhm is perfectly acceptable. Impedance is not his issue.

I'd be willing to bet it's either a bad cable, or more likely piss-poor connection inside the SP-24b. Of course, if it is the latter, and if he gets a transformer, and it happens to short the cold pin and the ground, that could solve his problem -- but so would just shorting the pins, and without the corresponding loss in SNR.

jw


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## Fred Garvin (Sep 4, 2010)

Enough with the thread hijack. You're over-complicating a very basic signal issue of using a balanced, low z device connected to a Hi Z, unbalanced input used on consumer level audio components - not pro audio gear. It may not even be the source of Syd's static but it's definitely much more susceptible to sending a dirty signal into his sound card.


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