[ Steve McCollum wrote in 060123 MMDigest:

> Check out the folks at Tracer Technologies (www.tracertek.com).
> They evolved from the Diamond Cut Audio, whose initial work was
> with vertical Edison recordings.
>
> I have a copy of their DCSix program, which works great.  I've
> transferred a number of vinyl LPs to CD using it, eliminating
> clicks, pops, and some hiss along the way.

Consider this another vote of confidence for the [Diamond Cut] DC audio
processing programs.  I have been using them since the first revision,
for well over ten years.  I have cleaned on the order of 500 78 rpm
sides, most well cleaned, some not so well, but always an improvement.

What one must bear in mind is that you cannot make a silk purse from
a disc that has been trod on with golf shoes.  Application of the
heavier filter characteristics almost always destroys the ambience and
coherence of the sound, so it's always best to think in terms of how
little one can do as opposed to how much.  In any case, the huge
repertoire of filters and tools found in DCSix is about as complete as
it gets, and one can get thoroughly professional results with patience
and practice.  There is never a turnkey solution -- every restoration
is different.

With regard to recording with flat frequency response to preserve
waveforms, it is also nearly impossible to do processing on files that
have been archived using MP3 compression.  The compression algorithm
includes "brick wall" high frequency filtering and destroys the
waveform characteristics of pops and clicks, so automated removal
cannot be done.  Manual removal is possible, but 'tedious' is not the
word to describe it: there can be tens of thousands of clicks in a
three-minute side.  The best strategy by far is to store the music
as WAV files, with all filters wide open and at a high sampling rate
(at least 44.1 kHz).

A. B. Bonds