What's the best solution to my noise problem?

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bq87

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I've got a condenser AT4033 and a dynamic Shure SM57 going into an old MobilePre Pre-Amp to record acoustic guitar on my laptop. I play pretty soft acoustic guitar, and there seems to be a problem since the signal from the SM57 seems to be too low and I'm getting a huge amount of noise (to the point where the recording is largely unusable). When I adjust the gain on the pre-amp (and on the pre-amp control panel) I get a signal that is normal, but again, there is a huge amount of noise. The funny thing is, when I listen to myself play through the pre-amp's direct monitor (aka listen while I'm playing) there is a noticeably smaller amount of noise. It's only when I playback the recording through Adobe Audition that I hear noise (and only from that one mic). So I can't tell where the problem originates, and what the solution would be. Is it:

a) The mic isn't sensitive enough for what I'm doing?
b) The pre-amp isn't good enough?
c) My computer's sound card sucks and is adding on noise.

It's a problem I want to fix but I can't come to a conclusion on where the problem originates. Thanks!
 
bq87 said:
a) The mic isn't sensitive enough for what I'm doing?
b) The pre-amp isn't good enough?
c) My computer's sound card sucks and is adding on noise.
Click to expand...

a) This is not likely to be a problem
b) The preamp delivers a line-level output. If you are going from the pre into a mic-input on the computer, that may cause you some grief
c) Computer sound card is likely to be the main culprit.

Suggestions: Get a recording audio interface. Ditch the preamp, and bypass the computer's soundcard
 
Just FYI: It was a pre-amp into a USB port.

And thanks for the response, I've honestly been researching this for days without a good solution. Will look into a new sound card now!

Edit: And I'm looking into the recording audio interface as well, though I'm not too familiar with it in general.
 
Last edited:
" What's the best solution to my noise problem? "


duct tape if you're married.

:thumbs up:




:laughings:
 
So apparently I have an audio interface, even though I've been calling it a pre-amp (it advertises as a pre-amp and has one built in). So does this mean the sound card on my computer is not the problem?
 
If the mobile pre connects via usb, then the built in sound card doesn't play a part in your recording.

If the mobile pre connects via some analog audio cable, then audio's going through the internal sound card.

Hope that helps. :)
 
Okay, looks like the mobile pre is in fact an interface.

If you are recording through this, connecting to the computer via USB, and if you are listening to stuff through it and not using the computer's sound card, you should not be experiencing noise problems.

You now need to describe the noise that yo are getting. For example, is it ambient room noise (such as computer fans)? Or it could be noise coming from a bad microphone cable. The computer itself maybe generating noise when you play back material.
 
I've attached a few mp3 recordings (about 5 seconds each) to show the problem. One is the dynamic which is giving the noise problem, and the other is the condenser which records fine. The dynamic is gained as high as I could set it, and I still only barely get a normal amount of volume (with a lot of noise). The condenser is set way lower, and gives a much better quality recording.

The dynamic is set at the 12th fret about 4 inches away from the strings. The condenser is angled toward the sound hole about 7-8 inches away.
 

Attachments

Hey.
That's the noise floor of your preamp.

The reason you hear it with the dynamic mic is because dynamic mics (generally) require more gain than condensers in order to achieve the same output level.

The higher the gain, the more hiss you're gonna hear.
The solution really is to stick to condensers, or to upgrade to a better interface or a quality preamp before your current interface (if it has line inputs).
 
When you play back using Audition & hear noise what are you listening through?
Speakers from soundcard?
Headphones from soundcard?
Speakers from interface?
Speakers from interface???
57s take a HUGE amount of gain to get going.
Do you have the same noise problem with the condenser?
How far is the guitar from the mic when recording?
 
rayc said:
When you play back using Audition & hear noise what are you listening through?
Speakers from soundcard?
Headphones from soundcard?
Speakers from interface?
Speakers from interface???
57s take a HUGE amount of gain to get going.
Do you have the same noise problem with the condenser?
How far is the guitar from the mic when recording?
Click to expand...

He posted clips and mic position descriptions above, ray.
 
Doh,
the clips must've been posted when I was typing - I didn't go back and read after posting.
Given the clips all I can offer is...
What Steen said!
 
In fact there isn't much difference in the noise floor in those clips between capacitor and dynamic mic, both run at about -45dBFS which is frankly crap and worse than a decent casstte machine SANS Dolby! This does however assume that the MP3 encoding has not somehow screwed with the noise content? It IS largely LF noise below 500Hz. What do the AA meters show in the original .wav?

All that said the SM57 is very gain hungry and really not suited to acoustic guitar for this reason. My son however prefers the 57 to both my AKG P150s and my Sontronics STC-2 but we do have the "luxury" of an A&H ZED10! (into a 2496, noise floor at a VERY quiet 2am ~ -70dBFS).

So sorry, bottom line, better interface. For this purpose and if you like the sound of the Shure, the NI Ka6 AI has very clean mic pres and is every bit as good as the ZED10/2496 setup.

Lastly. You appear to be recording too hot. The average level should be around -18dBFS with peaks to no higher than about -10. With a quiet interface running at 24 bits you can still pull the signal up post tracking if needed with no noise penalty.

Dave.
 
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