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Re: [ARSCLIST] playing 78s

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 mbiel@xxxxxxxxx

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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