When you don't have a 78 rpm turntable...

[Circlotron]

Today I was loaned a pair of old 78's from the (19)30's to see if the sound could be restored somewhat. First step is to digitize it and put it on the pc. Well, I don't have a 78rpm capable turntable, only a 33/45 one and so I was thinking about getting access to the dc drive motor and shoving in a higher voltage and see how I go. Then I need a stroboscope for 78, and on it goes... Then it struck me (and I'm sure I am re-inventing the wheel again, but I hadn't heard of it before so there may be others too) to play the disc at 45 rpm and record the disc using Cooledit as I usually do, but in a file format that has no file header information. I used ascii with no file header. For sampling rate, instead of the usual 44.1kHz (because it was to end up on CD) I chose (45 / 78) x 44,100 = 25,442Hz. Then when you re-open the file it prompts you for 8/16 bit?, mono/stereo?, and the sampling rate. Instead of typing in the original 25442 Hz you recorded it at, put in 44100Hz. Then voila! the file plays proportionally faster and sounds jusst as if it were recorded at 78rpm. As a bonus, the cartridge will track the record better at these lower speeds, extracting every last ounce of information. I recorded it as stereo, though it is obviously not, and will denoise it as a stereo signal then combine it back to 2 channel mono.

 

[Christer]

Whoops! Did you use your ordinary cartridge? As far as I know
78s are supposed to be played with a very different stylus
geometry. The tracks are much wider and deeper, I think, so
your stylus will probably go too deep. Not sure what will happen,
but I guess you will get extra distorsion, and possibly even
risk destroying your stylus.

Also, 78s did not use RIAA correction, so you will have to
compensate for this. I understand they often did use correction,
but there were a number of different ones. Other will probably
know more about this.

 

[Havoc]

You can denoise in stereo and then combine, OR first combine and then denoise. By first combining you get rid of all noise that has a common mode and the useful signal will have gained 6dB.

Also check first if one side is not lots better than the other. If so it mey be usefull to work with only one channel.

Since you are using CEP, go to their forum: LOTS of threads on 78rpm, denoising etc.

 

[dice45]

Circlotron,
please use a spherical stylus. This is s must. Then you ough to find out which EQ was used for the shellac. It could be whatever, just one thing is sure: it is NOT RIAA.

I doubt the 45rpm give you advantage in extracting the signal, but anyway, it works ...

Havoc,
could you post the link to that forum?

 

[Havoc]

The forum can be found at: http://forums.syntrillium.com/

You will find info on vinyl-cd transcription and much more. Generally not audiophile minded, so watch your steps

Cyclotron: if you need a reasonably cheap 78rpm stylus, check out Stanton http://www.stantonmagnetics.com/alpha44/reviews.asp . For most cartridges they have a 78rpm stylus, and if you don't care about price, they make to spec. I paid about 100 euro for the cartridge (680hifi) and again about 100 for the stylus (d6827).

 

[dhaen]

Equalisation

There were very many equalisation types used. Many producers used more than one kind, as time passed.
It might be impossible to be sure which curve was used. You'll have to let your ears be the judge, and apply eq. experimentally.

 

[Circlotron]

Well I've done it now. Here's the results. I used Sound Laundry for the actual denoising. This is part of the original.

 

[Circlotron]

This is the denoised version of same.