I've been thinking about getting some high-resolution FLAC files off some of these old 45s I picked up over at the pawn shop for a few bucks. They're not in the best condition, but they make pleasant sounds, and that's awwwright.
Anyways, this fancy USB turntable allows for recording in up to 48khz/16bit audio and has three speeds with quartz speed lock - 33, 45, & 78. I was disappointed that the turntable only would let computer have 16bits, and especially disappointed in 48khz, so I came up with an idea ...
Perhaps I could record this 45 at 33+1/3 ... Then I could double the sample rate and halve the speed in Audacity, creating a 96khz version of the 48khz track. This perfectly preserves the 48khz track, but effectively doubles every piece of data. I could then use speed correction to up the speed 35%, giving some higher frequencies than 24khz (and a generally higher quality overall).
Or so I thought ... My concern is that the digitized material recorded at a lower speed will amplify any surface noise present (which is everywhere on these dusty suckers). Also, won't bass frequencies suffer? Is this small amount of bass loss a worthy cost for the incredibly amount of treble gain (which has now shot from from 24khz close to 30khz according to Audacity's useful spectogram)? Another issue is all that unused data in the 96khz track ... why have 96 khz when only 60 are used? Is this file space a big enough deal?
Well, I'm really unsure about all these questions. So I thought I might ask some pros.
Attached I've included two small snipets.
1) 20 seconds or so of an album recorded at 33+1/3 rpm, digitally doubled to 96khz, and sped up to 45 rpm.
96khz.zip 3725k .zip file
2) The same 20 seconds or so of the same album, but recorded at 45 rpm (still 48khz).
48khz.zip 2332k .zip file
I've tried using Foobar to ABX the two tracks, but still can't decide ... All opinions are appreciated!