Capturing audio from analog tape - use NR or no?

[sphinx99]

Scenario - a wide variety of cassette and reel-to-reel source material, some recorded using Dolby NR products of various kinds (internal and external) and some not. No idea what used what, or whether the material has aged enough that it does not matter.

Is it better to capture with NR off and do software-based NR at some later time?

Right now capturing information before the tapes degrade is more important than reducing noise.

[midders]

Is it better to capture with NR off and do software-based NR at some later time?

Probably. Most of the Dolby NR schemes (A, B, C...) artificially boosted some of the higher frequencies and then later reduced them to cut out hiss. I would expect that modern audio processing software can reproduce this easily and can probably improve on it.

Slainte

midders

[netmask56]

When I do restoration work I nearly always turn off the NR on a cassette machine and do any processing on the computer. The other thing to look at is the azimuth of the playback head - make sure it is truly 90 degrees to the tape. Typical sound when the azimuth has drifted is a "swimming" sound or a sort of phasing especially noticeable with mono material. If you can playback the tape on the machine it was recorded on chances are it will sound ok. The azimuth can be adjusted generally with a small Allen key BUT BE CAREFUL http://www.audio-restoration.com/cassette.php

[sphinx99]

Azimuth isn't an issue; I have Nakamichi Dragon, CR-7A and DR-1 decks all in fine condition and ready for the job with working adjustment on the playback side. (And a Sony KA3ES, Tandberg 3014 and my trusty old Sony WM-D6C portable... can you tell that I'm a collector?!) I also have a few reel decks but none are in good shape so I need to think about how to tackle that one. Capture would be through an E-Mu card I have (old but still seems to work great) at 24/48 or 24/96. (Disk space is cheap; I want to do this once with no regrets or recriminations, so I might go overboard on the sample rate.)

I know I can adjust azimuth but the NR was what I wasn't sure about. I take it as a given that any NR done by a Dolby analog circuit from the 1980s can be done in software today--and done better--but I wanted to be sure. I know I trust Neatvideo over any video NR on any video playback deck or proc amp I've ever used, but I'm not so experienced with audio and I sense that software audio NR is a less sophisticated and polished art (compared to video) and probably always will be.

[netmask56]

Adobe Audition, CoolEdit Pro etc can all do good restoration. If you are willing to afford a few of the WAVES Ltd plugins they have a fine set of restoration tools. But there are many free audio plugins available as well as what is built into Audition etc.

If you have a very hissy tape than investigate using a low pass filter to get rid of the hiss followed by harmonic restoration to put the highs back in. This technique has been applied to early Edison cylinders where the cut -off frequency was set at 2KHz!!! but with harmonic restoration the final results sounds like a bandwidth up to about 5 or 6Khz. It adds highs without adding noise. Good to hear you have a Nakamichi in working order. I have heard some dreadful results from a few engineers in a not to be named recording studio, I was visiting, who knew nothing of azimuth effects and blithely processing a tape for a client that was badly off azimuth. When I questioned him the reply from the kid was "Oh that's called flanging I suppose it's not your sort of music.." was the smart alec reply...

[olyteddy]

Here's an interesting WinAmp plugin. http://www.winamp.com/plugin/tape-restore-live/154246. Does Audacity accept WinAmp plugins? (I don't have it installed on this machine and am too lazy to boot the laptop.)