recording twice

[Dan McDonald]

Just was wondering if anyone has tried recording discs twice and using the information to get rid of unwanted noise.

For old 78s and similar material, there is sometimes a lot of wear that can cause various noises. Using one size stylus avoids some of the noise but leaves another type, using a different size stylus can get rid of the one type but introduce another type.

I was just thinking that one could make two different recordings then sync them up using the "convert files" procedure and use the information that exists in both signals in some way to get rid of the portions of noise that only exist in the recordings using a specific needle size.

Anyway, just an idea - has anyone tried this?

Dan McDonald

[Rick]

Re: recording twice

Interesting idea. I think that the biggest problem would be repeatability of the turntable. Wow and speed accuracy would make the two recording slightly out of sync over the length of a song. You may have to add a step of pitch change to get rid of any minor speed diferences. You still would be left with Wow and Flutter differences, but that might not be too bad.

Rick

[Craig Maier]

Re: recording twice

I think that the two signals would literally have to be phase locked to each other for this to work, else there will be a lot of artifacts produced by the delay time between the two sources. Not sure how to do this. But it is an interesting idea if that problem can be overcome.

[greg_m]

Re: recording twice

I tried this a few years ago, and discovered the problem that you've predicted: the turntable speed was not exactly the same for both recording sessions, producing phasing errors. This was with a "high end" crystal controlled, direct drive turntable, too!

I think the only way to do this successfully would be to use a turntable with two (or more) tone arms mounted as close as possible to each other, and essentially do both transfers at the same playing. This would eliminate the long-term speed errors, but still might have small errors (the rotational speed of a given place on the groove could be slightly different when passing one stylus, compared to the other stylus).

[Spaceman]

Re: recording twice

Systemically speaking, several good points are made in the above comments. A further point to consider is the age of your pressing. Older / dirtier records will have a small amount of dirt at the bottom of the groove which, to a certain extent, affects the playback. I often play a record twice when I want to get the best possible recording- once to loosen/remove debris (several people tell me it is ideal to play it 'wet' during this phase) and the second to actually capture the audio data. One really can't get _all_ the dirt out of the groove, but it's effect can be mitigated significantly by this rather time-intensive process.

J

[This message has been edited by Spaceman (edited 09-28-2002).]

[Craig Maier]

Re: recording twice

Warren Vache' Sr. had suggested to us that we transfer the records that he provides to us for release, but only after coating them with Armor All (yes - that stuff that you use to clean the plastic in your car with). I had warned him that I did not know what the long term effects that the chemical reaction could have on the shellac, but he did not care about that. So, we have been doing that. What happens is that you have to play the record about 3 to 4 time to get all the dirt out of the groove after you perform this operation. The stylus will keep on clogging up and you will have to keep on cleaning the junk off of it. However, ultimately, when the record plays completely through without having to clean off the stylus, it is ready for transfer. The transfer is most definitely less noisey than it otherwise would have been. Also, the record looks about one grade better after this process (although, I am suspect as to what it will look like 10 years afterwards). So, you might want to consider giving this process a try, if the records are not extremely valuable.

[SPIKOVSKY]

Re: recording twice

I'm a complete tyro at all this,indeed I was just browsing around and happened on this site!But...the idea of synchronising two recordings from two tone arms could be got around by mounting another record head at the correct distance apart onto one tape recorder,each served by its own preamp etc.,and recording in the 'sound on sound'mode! Of course getting the correct adjustment between the two heads would be excruciatingly delicate,but if you do a lot of this type of thing ,might be worth the trouble!You would then have to cope with any tape hiss,but I imagine that that would be no problem.
Years ago,when I transfered all my records onto cassette (before I knew about computers) I would spray the record with 50% distilled water-50% alcohol.Imade an arm with a roller of velvet that tracked with the tone arm and insured that the needle was always running in a pool of liquid.This reduced hiss enormously and cleaned off the record in a way that no other method equaled.The roller was 2 inches wide,so there was plenty of contact in the revolutions.Indeed every playing of thr record involed several thousand passes of a very soft brush.One had to make sure to dry of the record properly after of course,but as you would now be more likely to play the cassette,it didn't matter that much.I had a very powerful turntable,so any drag effect would have been theoretical!