software for noise reduction/archiving

http://www.digidesign.com/products/details.cfm?product_id=1041&template=overview

Any kind of gate or filter is a more global thing, this takes a picture of the noise from a silent part of the recording and tries to remove it from the rest.

Beyond that there are pro systems like Ceder and Sonic Solutions which used to be the standard for cleaning stuff transferred from vinyl.

The fundamentals, however, would be the same for Mac software.

To reclaim vinyl with ticks, pops and crackle, you need algorithms within the editing software that do just that. Most are easy to start using as you can run them in preview on just about any desktop computer and hear the changes, the actual clean up. When you come up with something you like, then you can apply it to the .wav file and make a copy of the cleaned up material. Using them just right take some practice but it's not so steap that you can't do things in a reasonable amount of time and achieve good result.

These filters are great but not perfect. When you treat a stereo signal in this manner and clicks, pops and crackle are removed, you're essentially removing small slices of information and replacing it with -- generally -- a microscopically muted insertion.
The more you do it, the more musical information is removed.The result can be a narrowing of the stereo field, a loss of some punch.
Some of this can be added back by using expansion or compression, or again doing an EQ tweak. Once you get into it, you acquire experience by doing and find out what works and what doesn't.

To do straight noise reduction, you will likely want to use a software with an algorithm that samples the constant full spectrum noise (for example, tape hiss, hum, buzz, rumble from vinyl/turntable). You do it by going to the beginning or the end of the track -- or a moment of silence where the music is not going, but the noise is. The software takes a snapshot of that spectrum and then uses it in a subtraction-like scrub of the entire file.

You can apply just a little to reduce noise below a general threshold of hearing determined by you, or try and get rid of all of it. The more you squeeze the algorithm, the more noise you remove and it is not without cost. In its place you get a lower level pink noise and some time slurring of the traffic. If you've had recordings on remasters of demos and such where the tape or old vinyl source was really stepped on by such a filter, you'll hear a kind of crystalline twittering sound in the quiet parts.

You shouldn't have to pay $1200 for pro quality software to do this.
Diamond Cut cost me -- oh, it's been a long time now, about $300 tops. Cool Edit Pro was around $250. There must be something in the same ballpark for Macs.

they've got a higher resolution one out now I haven't tried yet: http://www.waves.com/content.asp?id=2027

and the Sony Oxfords from last year got great reviews: http://news.harmony-central.com/Newp/2004/Oxford-Restortion.html

you have to be very careful with these -- a very light hand -- they do subtract the hiss and pops, but they also take the sting off any transients, make drums sound like wet shoes

the Waves X-Noise is brilliant -- you select a section of the audio with just the hiss, hit 'learn' to learn the noise profile, then re-select the entire file you want to subtract the noise out of and raise the threshhold / reduction a tiny bit at a time . you can flip to 'difference' to hear exactly what noise is being subtracted out of the signal, and if you're hearing anything but hiss -- like little wispy bits of the high hats, or sybillants -- then you're taking too much away, pull back on the reduction.

another thing to keep in mind -- though it's possible to totally remove _all_ noise, you should seldom do this -- you want a light touch, often hiss acts as a bonding agent for the mix and taking all of it out leaves the sound dead & dull.

I use these for more than noise removal, they're great.

so first, am i missing anything?

and second, what's the correct order do do this stuff in? the order i laid out seems intuitively correct (hiss filter will work best before other tweaks, etc.) but maybe decrackle should go first?

if you can get a hold of actual restoration noise removal software, do -- much better than a hardcore no-way-back low pass filter

fancy noise removal softwares aren't low pass filters -- think of them as 500-band EQs set very sharp to only subtract out the hiss, leaving any high end frequencies above the hiss range still intact. not like there are going to be many of them on a cassette, but I was often surprised at the difference

A constant noise sample and remove algorithm set (or plug in) would seem necessary, too. Low pass filters, band pass and notch filtering is nice to have around but not really the same kind of bird.