Grateful Dead
February 18, 1971
Capitol Theatre, Port Chester, NY

SBD -> Dolby A Reel -> Dolby A decode -> DAT -> Sound Forge NR  -> CD-R

The Sound Forge noise reduction was used to attenuate a very narrow
frequency band (in the vicinity of 8000 Hz) which was present as
interference on the original reels.  See my notes below for details.

Disc 1

Set 1
1. Bertha (7:13) *
2. Truckin' (11:03)
3. It Hurts Me Too (7:42)
4. Loser (8:21) *
5. Greatest Story Ever Told (3:45) * >
6. Johnny B. Goode (3:39) *
7. Mama Tried (3:29)
8. Hard To Handle (8:01)

Disc 2

1. Dark Star > (7:03)
2. Wharf Rat * > (7:21)
Set 2
3. Dark Star > (7:14)
4. Me And My Uncle (4:04)
5. Lucky Lager Dance Time (2:39)
6. Casey Jones (6:10)
7. Playing In The Band  (5:09)
8. Me And Bobby McGee (6:06)

Disc 3

1. Candyman (9:46)
2. Big Boss Man (5:40)
3. Sugar Magnolia (8:29)
4. St. Stephen > (5:57)
5. Not Fade Away > (4:33)
6. Goin' Down The Road Feeling Bad > (5:01)
7. Not Fade Away (3:59)
8. Uncle John's Band (6:44)

  * first performance

The original reels of the Port Chester run of '71 were audibly
tainted due to a cable problem. The result is a tone which hovers
around 8000 Hz with an amplitude of about +20 dB above the noise
floor. This translate to a very annoying pitch, especially during quiet
sections, which is in the old-tv-tube or lousy-hard-disk or maybe even
the-sound-you-hear-after-you-slam-your-head-against-a-concrete-wall
class of 'whine'. Because this interference is 'monochromatic' it's
easy to get rid of if you have the processing power and a quick
FFT algorithm. I used the filter-shaping capabilities of the Sonic
Foundry Noise Reduction Plugin to tailor a very narrow notch filter
which attenuated the interference without affecting the rest of the
signal. And it's all done in the digital domain. Huzzah!

As a side note, I actually ended up crafting many filters to process
these shows. The frequency of the interference actually drifted anywhere
from 7700 to 8100 Hz during a given show. This was probalby due to a
slightly wandering reel speed. It made my work harder but when I tried
a much wider filter I started to be able to hear the attenuation in the
music. The filters generally go like this:

25 dB     /- - - - - - - -\
         /                 \
        /                   \ 
0  dB  |                     |
       7830      7900      7970

The end result is no more annoying whine! 

I also removed some of the nasty mic feedback in the 2/18/71 Bertha
using this type of filter.

Leigh Orf <orf@mailbag.com>
