Noise Removal in Audacity - Frequency Smoothing

winkosmosis said:
The only advice I'm arguing is the advice to "use 48khz because your quality sucks anyway". I've been TRYING to explain that less than optimal quality in part of the process doesn't somehow mean that sampling at a lower rate somehow makes sense, and that the opposite makes more sense-- Sample at 96khz to capture more information for postprocessing and for better downsampling. Unfortunately the "Nyquist says..." dogma is pretty hard to cut through. Try as I might, I can't convince you that downsampling 48khz->44.1khz is worse than 96khz->44.1khz because you're convinced that 48 and 44.1 are both lossless reproductions of real sound because "Nyquist says..."

My friend uses Final Cut, which I can't since I'm using Windows. I'm still deciding which video editing program to use, which I'm sure will have its own noise reduction setup.

BTW I ordered the Rode NT1-A condenser, supposed to be the "quietest studio mic in the world". I'll report back on the noise level with the DR-40
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No. It's you that doesn't get it and is being dogmatic.

I agree that it is sound practice to record at the best quality you can... but within the limitations of your equipment. You can record at what sampling frequency you like and it won't do any harm but there will be no benefit if your equipment is not up to capturing the extra quality and that's the problem you have and don't seem able to accept.

Your new mic will certainly be an improvement. If you can avoid the need for noise reduction then you will not be throwing data away. That leaves your Tascam recorder. While they are pretty good they still have their limitations (they seem to have a reputation for noisy recordings so you may not totally eliminate noise in your recordings). At the price they are there will have been compromises in the design as they will have been made to a price and it is not clear to what extent you are able to benefit from the higher sampling rate available given the design/manufacturing compromises they made. I suspect that they have made the higher sampling rates available because that looks good in a sales brochure when they would have been better to have provided better quality pre-amps instead and so reducing noise levels on recording - but that's not very "sexy", unfortunately.

Sample at 96 kHz. You seem determined to do so but be aware you may not be gaining much, if anything by so doing but you will need a lot of hard disk space. In the end it's your choice. The response to the original question was to get better equipment and avoid the need for noise reduction. Do that and you will be better placed to benefit from your chosen sampling rate.

I do all my recording at 44.1 kHz/16 bit because with my equipment and for the uses I put my recordings to, my ears tell me there is no benefit in going any higher and I've known others who've said the same.
 
Tootler said:
No. It's you that doesn't get it and is being dogmatic.

I agree that it is sound practice to record at the best quality you can... but within the limitations of your equipment. You can record at what sampling frequency you like and it won't do any harm but there will be no benefit if your equipment is not up to capturing the extra quality and that's the problem you have and don't seem able to accept.

Your new mic will certainly be an improvement. If you can avoid the need for noise reduction then you will not be throwing data away. That leaves your Tascam recorder. While they are pretty good they still have their limitations (they seem to have a reputation for noisy recordings so you may not totally eliminate noise in your recordings). At the price they are there will have been compromises in the design as they will have been made to a price and it is not clear to what extent you are able to benefit from the higher sampling rate available given the design/manufacturing compromises they made. I suspect that they have made the higher sampling rates available because that looks good in a sales brochure when they would have been better to have provided better quality pre-amps instead and so reducing noise levels on recording - but that's not very "sexy", unfortunately.

Sample at 96 kHz. You seem determined to do so but be aware you may not be gaining much, if anything by so doing but you will need a lot of hard disk space. In the end it's your choice. The response to the original question was to get better equipment and avoid the need for noise reduction. Do that and you will be better placed to benefit from your chosen sampling rate.

I do all my recording at 44.1 kHz/16 bit because with my equipment and for the uses I put my recordings to, my ears tell me there is no benefit in going any higher and I've known others who've said the same.
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Do you also upsample to 48khz? I used to set my soundcard to 48khz because I figured it was better, but while trying to decipher bird song recordings at 44.1khz from a pocket recorder I realized it was distorting the sound. I set it to 44.1khz and the distortion went away. Of course that make sense, you can't change sample rate and not lose quality
 
winkosmosis said:
But noise is additive is it not? If the mic adds nearly zero noise and the DR-40 adds a little, that's better than noise at both steps
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That depends on which piece of gear was making more of the noise. If you can identify the weakest link then you can replace it and things will get better.
 
bouldersoundguy said:
That depends on which piece of gear was making more of the noise. If you can identify the weakest link then you can replace it and things will get better.
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I did some experiments with the DR-40 and US-144, recording with no mics attached and phantom power turned off. Here's a screenshot-- The top 2 are the US-144 at level 8 and level 10 on the gain knobs. The bottom 2 are the DR-40 at 70% and 90%. Noise on the US-144 is lower and also looks like a pretty consistent square wave which I'm guessing is easier to remove with software. Also the noise on the right and left channels of the DR-40 are at different frequencies

w855ds.jpg


The problem is that level 8 on the US-144 is too low even with the Behringer C-1 inches away from my mouth speaking normally! Here is what the noise looks like at level 9 which is loud enough

6pspvk.jpg
 
The problem is that level 8 on the US-144 is too low even with the Behringer C-1 inches away from my mouth!

Micless noise upsampled for 384khz for easier visualization, US-144
ndrk74.jpg



Micless noise upsampled for 384khz for easier visualization, DR-40
55ryfp.jpg
 
Update: Got the Rode NT1-A and it's noticeably quieter! But I've flown to Texas and and I think the journey damaged the DR-40 and now rather than just being noisy, it has weird crackling sounds and a fluttering type sound. I could have sworn I packed my Tascam US-144 but apparently I left it in Hawaii, so I went to Guitar Center and bought a UR-22. Also got a trial of Adobe Audition and I'm abandoning Audacity, especially since I found out it relies on the Windows audio stack and doesn't support ASIO.

BTW, I'm recording some war stories from my future stepdad, who is a WWII veteran. I'm going to submit them to the Library of Congress which asks for 96khz 24 bit http://www.loc.gov/acq/devpol/colloverviews/sound.pdf
 
". I'm going to submit them to the Library of Congress which asks for 96khz 24 bit "

Not quite. That is their "preferred" format. They would like the "highest bit rate and word length possible" So why not 192kHz then? Obviously they will accept what they can get. If you had Nixon's last gasps on answerphone tape they would have your arm off!

Dave.
 
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