There has been a good deal of talk about some of the OTR groups
around cleaning poor sounding material.
Cleaning, where appropriate, is something that I agree completely with
and do in a VERY conservative way when needed.
However, there are significant risks inherent in
doing
so that can completely degrade the quality of the original material beyond
repair when done poorly.
In my experience, and I have made every miserable mistake
possible, there is often a desire to completely remove all noise, pop and
crackle
from the material in order to make it as clean as possible. This must be
avoided.
With lower generation material, I recommend avoiding
reprocessing with the following exceptions: equalization to restore fidelity to
the
proper
curve (this takes some research), removal of any 60 Hz hum and turntable rumble
where needed, and PERHAPS some very minimal removal of crackle. Anything greater, will lead to the sound of
"thumps" where the crackle and pop has been removed. Too many folks have
ruined
low generation recordings (especially from 78 rpm masters) by trying to
wholesale remove the existing surface noise.
Our folks in
the
78 RPM groups have learned to leave this in as it really winds up enhancing the
vintage nature of the material. Why
would we want
something
from 5 years ago to sound like a new
recording. The result of aggressive
noise reduction to surface noise results generally in
the
introduction of serious digital artifact sounds in and around the 7000 Hz
range. These are virtually impossible to
remove without
ruining
the low generation fidelity of the recording.
This is a common and often fatal mistake.
With higher generation recordings, we are dealing with different
issues. These include a loss of fidelity
from multiple copies over
the
years, as well as the introduction of multi-generational tape hiss. This problem is really the most difficult to
deal with and the
one
where most of the problems with cleaning occur.
There are ways to address this that can help. First of all, it's important to assess,
within
the frequency range, where the recorded material cuts off. From there, one can
use a graphic equalizer to remove hiss beyond that
point. Also, before or after this step, it may be
possible to use the equalizer to reduce the low end of the sound spectrum
(which often
becomes
exaggerated with multi generational recordings) as well as to carefully enhance
the existing upper range to increase sound clarity.
At that point, I use a filter to reduce any 60 Hz hum (very
common) and only then carefully look at noise reduction. In extreme cases, it
is
rare that all of the offending hiss can be removed. However, in the absence of low generation
masters, this may be our best
alternative.
But sometimes such noise
can be removed without degradation and introducing artifacts. I do this by
looking for a "quiet"
interval
in the recording; e.g., pauses between speaking. This interval can be used to
make a noise profile. This profile is often accurate
accurate
for the entire recording. This profile can be used to subtract the noise from
the recording. Sometimes several profiles are needed to be applied piecemeal
throughout the according. I have had some excellent results with this method. The longer the "quiet" interval the better the results.
But this method isn't perfect. If there are pops or clicks in
the quiet interval, they should be avoided, because they can bias the measuring
the
background
noise floor. You still must listen to the results to determine if the sound was
improved. There are instances where I had to reject this method because there
was little to no improvement, or I removed too much information and degraded
the recording. This is usually caused by the "quiet" interval containing
useful information that was buried in the noise and too hard to discern.
This is exactly what I do when I use noise reduction. Great minds think alike. Often times, In
cases such as this, I'll look for a
talk/music/audience
noise free section and manually remove any pops and clicks remaining before
applying a very conservative de-noising.
However, I still find the results from 78 RPM transcriptions to
be generally very poor. With these, I do
my de-noising up-front and the
old
fashioned way. I clean the disc, vacuum
it and sometimes wet play it with a light mix of gentle hand soap. How's that for technology!
Last word, be CAREFUL about the
software you use. For PC's the only good
and effective software out there is expensive.
I do not
recommend
Sonic Foundry/Sony plug-ins to recording programs. These almost always leave phasing and
artifacts. The program Raygun can be helpful but potentially dangerous for
artifacts if not used with great care.
The best programs are those marketed by WAVES. These should be seen as the standard. They are expensive. If you can afford them, use them. IF not, I recommend avoiding the temptation
to do any
reprocessing.
There are enough of us out her that can and will assist with
restoring rare material. All you have to
do is ask. I do this regularly with
material
from ET's, cassettes, and open reel tapes.
I've also been able to do some limited re mastering with botched mp3's.