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Re: [ARSCLIST] playing 78s

I have been following this thread for a bit, and I would have to concur with Mike's assessment of the variable low-pass filter on the Packburn. Despite many attempts at trying to make this unit sound good, I have to admit I never liked it much.

Like most signal processors, if it was used sparingly, the artifacts weren't too noticeable, but high-amplitude pops or ticks could really put it over the edge.

Scott D. Smith Chicago Audio Works, Inc.

Quoting Michael Biel <mbiel@xxxxxxxxx>:

joe@xxxxxxxxxxx wrote:
IIRC the PB worked best with a stereo input to better define noise and make the choice of switching between groove sides. Better to sum the channels post-PB.

The PackBurn works ONLY with a stereo input, at least for the switcher
circuit.  There were three sections in it, and the first was the
switcher.  It listened to the two groove walls and decided which one
was the quietest at any point in the record.  If it did not have a
stereo source, how could it tell????????????  And how could it give one
or the other walls separately???  The original model gave an output of
either the left or the right.  The "Centennial Model" numbered 1977 and
issued in 1977 added a feature that would give the sum of the two
channels when both walls were equally quiet.

The second section was the blanker which was a mono impulse noise
eliminator, and this is pretty much what most other noise-reduction
systems in use are.  If all that was available was a mono source, this
still would work.   The third section was the dynamic noise filter
which we discussed yesterday.  This raised and lowered the top
frequency of the low-pass filter to allow more highs when the louder
musical content would mask the surface noise, but then reduced the top
frequency when the program content was quiet and would otherwise allow
the surface noise to be heard.  I HATED this filter, but as I mentioned
yesterday, Dick Burns LOVED it. Of course any of these three sections
could be switched in or out of the audio path. Mike Biel

John Eberle wrote:
Playing 78s through an RIAA preamp basically rolls off the highs and boosts the lows dramatically altering the frequency response from what it should be . The RIAA pre-emphasis eq curve is applied during the disc cutting stage of 45 and LP record mastering . 78 RPM records were not cut with RIAA pre-emphasis ; but rather were cut mostly flat with perhaps some low end roll of to control the size of the bass groove excursions .
A simple and cheap way to playback 78 RPM records is to connect the turntable or tone arm audio out to the HI-Z microphone inputs available
on many preamps . This will give the flat response desired for 78s and a little low boost will bring the lows back in to proper perspective . Also , most cartridges in current use for playing 78s are actually stereo and of course 78s are mono . It is totally weird to hear a 78 RPM disc being played with stereo clicks and pops . The cartridge can be wired in the headshell to reproduce lateral mono modulation only . This makes the record noise a lot less and less need for the Packburn or any other analog or digital transient noise reduction and better over all quality . If anyone would like an mp3 of one of my commercial 78s reproduced in this manner , just contact me off list and I will email it to you .
John Eberle : Over 27 years disc cutting experience and over 35 years in Mastering !
615-441-4660 **************Feeling the pinch at the grocery store? Make dinner for $10 or less. (http://food.aol.com/frugal-feasts?ncid=emlcntusfood00000001)

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