[Dixielandjazz] Restoring 78s

[budtuba at aol.com]

 Phil/Dick

I was going to reiterate Phil's method of playing the record at 45 rpm rather than 78 and will add my (horrendous to some) practice of appling WD40 to the record.? This also improves the playback helping the needle glide over much of the very high frequency noise that playing with steel needles in the early days machined into the groove.? I have yet to see any effect it might have on the record after 20 yrs.? Spray it on in two or three places and then hold a piece of bathroom tissues to the surface as it is spinning to spread it evenly and remove excess.? Even better than bathroom tissue are lintless towelette that are sold as cleaners for CDs because some of the paper will transfer to the record and I end up playing the record twice:? once to clean off the paper lint and secondly to record it.

Incidentally, the speed correction needed for CoolEdit to play back the record correctly after the recording at 45 rpm is as follows:

1.? The correct sampling rate to generate a CD is 44100 cps.? This is chosen when you chose to record and a popup screen gives you a table to pick from? With newer, faster computers than mine you could work at the higher frequencies.? For now, this is a reference rate.? I would pick 48000 cps and a sampling resolution of 32-bit. The 32-bit resolution makes the pop and click noise reduction even cleaner because these events are very short relative to the music you are recording.? A faster computer would even help more by choosing a higher resolution setting.

2.? Record the platter at 45 rpm.

3.? Do your pop and click reduction, and hiss reduction on this digital recording.? 

4.? In the pull-down menu for Edit, choose Adjust Sample Rate.? Instead of picking any of the cps settings in the table, type in:? 69333 cps.? (This is 78/45 times 48000.)? If you listen to this playback, the record will sound correct.? You could vary this slightly for known recording speed differences in some manufacturers.? For example, Edison and vertical groove Pathe records were recorded at 80 rpm rather than 78.

5.? In the pull-down menu for Edit, choose Convert Sample Type and pick 44100 cps and a sampling resolution of 16-bit.? This will then be a final speed-corrected file suitable for final filtering and tweaking before burning to a CD.? 

This procedure will take longer than a straight recording, but remember you are probably playing this record for the last time, so it is worth the effort.? 

I also save an uncorrected version of the basic record after step 2. just in case that newer technology yet to be announced comes along that further improves the process.? One program that I am impressed with is called Ray Gun Pro for removing transient pops and clicks and it is much faster than Cool Edit Pro.? I think it works on the Fourier transform analysis of the record rather than an inch worm analysis.? 

Without getting into the mathematical aspects of Fourier transforms, this is the method that astronomers use to remove effects of the atmosphere distorting telescopic images of outer space.? It also, I suspect, is how your method of removing noise by recording a section of the groove leading into or trailing from the music works.? Record materials have a noise fingerprint that results from the materials used in their construction and the history of needle wear and cracks that repeat.? This allows the software to get a clean image of those variables and it can be subtracted as you said, from the recording.? Similarly in the astronomical world, clean images of atmospheric distortion can be obtained by photographing images of "stars" projected down from space and subtracting the Fourier transform of the known star from the distorted Earth-bound image.



 


Roy (Bud) Taylor
Smugtown Stompers Jazz Band
Trad Jazz since 1958...we ain't just whistling dixie!

 


 

-----Original Message-----
From: Phil O'Rourke <philor at webone.com.au>
To: BudTuba at aol.com
Cc: Dixieland Jazz Mailing List <dixielandjazz at ml.islandnet.com>
Sent: Mon, 18 Feb 2008 10:25 pm
Subject: Re: [Dixielandjazz] Restoring 78s










Dick

I follow almost the same path with one major (I think) exception.
I record at 45 rpm to allow the needle to follow the grooves more closely. I 
then use speed/pitch correction in the program to bring the recording up to 
correct peed.

Phil O'Rourke
Australia


  There's been plenty of digital ink spilled on this subject here lately, but 
  I hope you'll allow me to weigh in.  While working on lots of pretty 
  wretched 78s for my Two Ton Baker web site, I put together a page 
  describing how I restore them.  It has notes, audio samples, and screen 
  shots of my audio editing program, CoolEditPro (although they're more for 
  decoration than enlightenment).

  See it at http://twotonbaker.com/2ton/music/restoration.htm

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