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Noise reduction of low-grade CD music

post #1 of 4
Thread Starter 
Hello!

Recently, I have been running into some low-grade music recordings with a high noise floor. This is material ripped from CDs as the source. Is there a noise reduction hardware or preferably software that can reduce this noise level as the music is being played from a PC or Mac? Or perhaps a tool that can process the music file itself? Also it would be nice to enhance the dynamics of old recordings back closer to what the music sounded like when it was recorded.

I remember there was Dolby which worked when music was played from a record or tape back eons ago. The only difference is the noise I am finding is part of the recording found on the CD and not introduced by the imperfections of analog sources like tape or vinyl. Of course if the noise reduction technique is too aggressive this can take valuable audio content away. So it should be capable of altering its processing based on the dynamics of the source playing at the time, with perhaps some user adjustable setting.

Any thoughts or ideas?

Bob Graham

PS: I know this is a double post, but I have asked the moderator to delete my previous post I placed in the wrong forum.
post #2 of 4
Thread Starter 
I know, this is a reply to my post. But I have been doing allot of research on the Internet. I think I am looking for sone kind of expander. There are allot of solutions if I was running a DAW. But I am not recording. I found one possibility, Audio Hiijack Pro, which accepts VST plugins. It comes with some plugins that may work. And there are probably some reasonably good free plugins for what I want. I could also hook in an equilizer in series to the expander with this software.

Any other good ideas? I cannot be the only one looking for this type of functionality. :-)

Bob Graham
post #3 of 4

What you seem to be describing actually are analog imperfections - just higher up the chain. An expander expands dynamic range - the opposite of the compressed dynamic range oft complained about on CDs, modern recordings... If it's tweakable enough, you may be able to get what you want. Dolby NR on cassettes worked by compensating for inherently noisy qualities in the medium during mastering (preemphasis), then undoing that (deemphasis) upon playback to return to a flat signal. Some old CDs actually do have their own preemphasis applied, but it's likely you'd know if you had to compensate for this... They wouldn't sound noisy, the EQ would just be all off. A noise gate is a rather specific sort of expander that will target hiss and whatever, above a certain frequency and below a certain amplitude. That's probably what you want to seek out, or try to set up an expander to work in the same way, or really anything that claims to denoise, dehiss, whatever.

 

I've never used Audio Hijack Pro, but I know it's popular. Additionally, any DAW or audio editor with VST support should allow you to take in your files, apply the plugin, and export your 'fixed' version. VST support in Audacity should even suffice.

post #4 of 4
Thread Starter 
I am playing with a compander right now. I am trying to figure how to set it up. But it already makes a noticeable difference.. Some CDs need to be expanded to a small degree. There are a few others that actually benefit from a bit of compression. At least this is the case for my headphone amp and my hearing ability. The compander has just a few controls, like attack, sustain, and so forth.

I looked into multiband expanders. I have a CD that has the instruments forward and the voice buried in the background. I also can pick the freq and amplitude as you suggest. However, I opened the edit screen of this type of expander to find what appeared to be a minature version of the cockpit of a 747 jet. Push a button, and another slew of controls pop up. I do not think I would ever figure out how to operate it!

Bob Graham
Edited by r010159 - 2/1/14 at 12:32am
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