FREQUENTLY ASKED QUESTIONS
Mr. Tipton:
I have been using the 4010 for playback of 78s for about a year and thought
I'd offer a couple of comments and questions. I am generally pleased with
the unit's performance; the greater number of settings offers more flexibility
in playback than did the Owl One that I was using previously and makes
easier the playback of oddball records, such as early Emersons with "45-
degree" grooves. However, I would say that the one thing missing is a good,
effective high frequency filter for playback of 78s. The existing filter on the
unit, when playing back 78s (which generally have significant surface noise),
appears to have negligible effect. I do use my old Owl multifilter (with three
notch filters of varying bandwidth) in conjunction with the 4010, but really
miss that high frequency notch filter that was part of the Owl One and
seemed particularly suited to playback of 78s.
One question concerning using the turnover control, which theoretically
compensates for the bass attenuation among the various record labels. What
I don't understand is, when selecting turnover downwards to progressively
lower levels (e.g., 250, 200, 150 Hz), I notice a corresponding significant
boost in the midrange frequencies - something I didn't hear with the Owl.
This effect is very obvious when playing back acoustically recorded discs.
Should adjusting the bass turnover "point" really affect the midranges?
Cheers,
Hello,
All designs involve some compromises and the 4010 is no exception. Our goal in designing the 4010
was to create a tool for archivists and others who are interested in digitally restoring vintage analog
records as accurately as possible.
One of our design maxims was, to borrow a phrase, “First do no harm.” That’s why we decided to
use a 2-pole Butterworth lowpass filter (-12 dB/octave) HF filter instead of aggressive notch filters
like those used in the Owl One which create too many issues in terms of frequency and phase
distortion.
Subjectively, our HF filter will have the most effect with a flat turnover and rolloff. The audible
effect will become less as the rolloff frequency is decreased because the rolloff filter is providing
a lot of high frequency attenuation. We feel that after creating as good a hard-disk image as possible,
(12 pages)
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