Condenser Microphone picking up laptop noise?

DarrenVocal

DarrenVocal

New member
Hello there people of HR, my AT2020 has been set to a confortable position and is placed right in front of my laptop. The only problem is that my laptop's noise is picked up from the microphone. Any ideas on how to prevent this?
 
You talking about the noise of the fans or is it some kind of interference?

Assuming ambient noise, the only way to cure it is to remove it. Maybe get a wireless keyboard / mouse and move the laptop right out of there, or get a long XLR cable and put the mic in a different room?

You can minimise the problem by
1: Keeping the mic far from the noise
2: Keeping the mic close to the source
3: Placing some kind of baffle between the mic and the noise
4: Keeping the noise in the null of the mic's pattern.

All these things will help but the absolute bottom line is that mics pic up noise indiscriminately (forgetting about HPFs, frequency response etc).
 
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^ What Steenamaroo said, but I'll add a couple of things.

First, on the distance. Sound follows what's known as the "inverse square law" Don't worry about the math but it means that every time you double the distance you cut the sound you're picking up to a quarter of where it started. So, if your mic is 1 foot from the laptop now, move it to 2 feet and the laptop noise will only be a quarter what it was. Move from 2 feet to 4 feet and you'll get to an eighth and so on.

The same law works in reverse. If you're tracking with your mouth a foot from the mic, moving to six inches will make you 4 times louder, allowing you to turn down the gain an further minimise the laptop noise.

One other item to mention is the aiming and pick up pattern of the mic. Your AT2020 is cardioid which means that directly behind it there's very little pick up. If you can arrange things so the laptop is directly behind the AT (rather than angled to one side or another) this will also cut the pick up.
 
By design, condensers are VERY sensitive.

A dynamic is less so and they reject ambient noise better.
(you'll see nearly every radio station in the past 40 years using dynamics: SM7's, EV RE-20s or MD-421s)

You really need a quieter computer tho.
 
TimOBrien said:
By design, condensers are VERY sensitive.

A dynamic is less so and they reject ambient noise better.
(you'll see nearly every radio station in the past 40 years using dynamics: SM7's, EV RE-20s or MD-421s)

You really need a quieter computer tho.
Click to expand...

Er, with respect, no. Big dynamics are common in AMERICAN radio stations but far less so in Britain and Europe where you see far more condensers--a mix of SDCs and LDCs (often the Neumann TLM series) depending on the station.

I sometimes wonder if this is why a lot of people on this forum like the RE20/SM7B sound while I don't find it very pleasing--maybe it's to do with the radio you listened too all your life?
 
Bobbsy said:
^ What Steenamaroo said, but I'll add a couple of things.

First, on the distance. Sound follows what's known as the "inverse square law" Don't worry about the math but it means that every time you double the distance you cut the sound you're picking up to a quarter of where it started. So, if your mic is 1 foot from the laptop now, move it to 2 feet and the laptop noise will only be a quarter what it was. Move from 2 feet to 4 feet and you'll get to an eighth and so on.

The same law works in reverse. If you're tracking with your mouth a foot from the mic, moving to six inches will make you 4 times louder, allowing you to turn down the gain an further minimise the laptop noise.

One other item to mention is the aiming and pick up pattern of the mic. Your AT2020 is cardioid which means that directly behind it there's very little pick up. If you can arrange things so the laptop is directly behind the AT (rather than angled to one side or another) this will also cut the pick up.
Click to expand...


You are close on this but the physics are wrong.

Every time the distance doubles there is -3db drop in SPL.

An increase of 10db is what we perceive as twice the volume. So 4 times louder is +20db.

In the OP's case if the laptop noise were, say at -30db at 1 foot mic distance, 2ft mic distance would take noise to -33db, 4ft= -36db, 8ft= -39db etc. In this example his mic would need to be around 9 feet away to decrease the perceived noise by half.
 
And in any case the surface the laptop is on and the wall behind the OP will reflect noise into the mic's pattern. Maybe put it under the table and use an external monitor, mouse and keyboard.
 
Muddy T-Bone said:
You are close on this but the physics are wrong.

Every time the distance doubles there is -3db drop in SPL.

An increase of 10db is what we perceive as twice the volume. So 4 times louder is +20db.

In the OP's case if the laptop noise were, say at -30db at 1 foot mic distance, 2ft mic distance would take noise to -33db, 4ft= -36db, 8ft= -39db etc. In this example his mic would need to be around 9 feet away to decrease the perceived noise by half.
Click to expand...

Sorry, but it's your physics that's wrong. As I said, sound follows the inverse square law. This means that, as you change the distance from the sound source, the formula for the change in sound intensity is the original intensity divided by the change in distance squared. So, if you double the distance, the new sound intensity is the original one divided by 2 (for double) squared or one quarter the original intensity.

As 3dB change represents a doubling (or halving) of sound intensity, that part of your statement is incorrect.

THIS graphic shows fairly clearly why this is.

As bouldersoundguy says, this doesn't take into account the effects of reflections etc. but, as a rough guide, it works--and getting your mic farther from the source of unwanted sound is rather more effective than just a linear equation.
 
What DID Steenamaroo say? Enquiring minds wish to know (but are too lazy to go back a page! :) )

On the original question, another thought. I live in nerd central and we have 4 laptops, a netbook and an iPad between the 3 of us. I've just listened to all for laptops and none of them make enough noise to worry a mic (even a condenser) a couple of feet away.

To the OP...do you have your mic on a desk stand without any type of shock mount? If so, at least some of your problem may be the direct transfer of vibrations (probably mainly from the hard drive or CD drive if you use it). In that case, buying a cheap floor stand with a boom arm could provide a lot of improvement.

Just a though.
 
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