digitizing 45 rpm vinyl

[JRSVader]

After digitizing all of the old vinyl collection the thought occurred to me that there might be benefits in running the turntable at 33 1/3 for 45 rpm vinyl and adjusting the speed later with Audacity. (currently running 2.0.2 on Windows XP)

I have read the tutorial article on recording 78 rpm records at slower speeds, and the manual entry http://manual.audacityteam.org/o/man/hi ... sfers.html but there seems to be no discussion on the advantages of 'lower speed transfers'

I suppose my question relates to the fact that now that I have one of these recordings in hand I'm not sure where to begin. I believe 'Noise Reduction' should be first, then 'DC bias removal', but I am not sure when in the process I should fix the speed. Should I take the RIAA equalization into account? Any thoughts out there?

[kozikowski]

there seems to be no discussion on the advantages of 'lower speed transfers'

That's because there aren't any. Transferring 78s without a proper 78 player has super serious problems and the only reason we post the process is that the only other option is to not transfer at all.

Speed changes in Audacity cause distortion and any time you play a record off speed, the pressing velocity process and RIAA curve become damaged causing frequency response problems -- and more distortion.

Transferring any vinyl without a good Phono Preamplifier will cause damage because there's no place to plug the hum suppression "third wire" from the turntable. Mmmmmmmmmmmm.

Koz

[DVDdoug]

Yeah... The reason it's sometimes done with 78's is because most modern turntables don't play at 78 RPM.

I believe 'Noise Reduction' should be first...

Yes, but you generally need to remove the clicks & pops before attempting "regular" noise reduction. If you don't do that, the clicks & pops in your noise fingerprint will cause too much of the good audio to be knocked-out, and you'll probably get artifacts. And, noise reduction can be "hit-or-miss". If the noise is bad, "the cure can be worse than the disease."

If the Audacity Click Removal "effect" doesn't give you adequate results. this page has tons of informatino and several software recommendations. I use Wave Repair ($30 USD). It does an amazing job on most defects in the manual mode, but it takes "forever". Wave Repair is probably not the best tool if you want to do it automatically.

then 'DC bias removal'

If you have a good preamp & soundcard, you shouldn't have any DC bias. But, there is no harm in using it.

Should I take the RIAA equalization into account?

If you use the right speed, the RIAA EQ built into the phono preamp should be fine. However, many older records have a rather "dull" high-end IMO, so sometimes I boost the highs a few dB. If you play at the wrong speed, the RIAA EQ will be messed-up. Since the frequencies being played from the record are not at the original-correct frequency, playback equalization is going to be applied at the wrong frequencies.

[JRSVader]

So I should correct the speed first to get the RIAA EQ correct, then proceed as normal? It does seem to make the pops easier to see, this is a very quiet recording and not much needs to be done.

[steve]

the thought occurred to me that there might be benefits in running the turntable at 33 1/3 for 45 rpm vinyl and adjusting the speed later with Audacity.

An interesting idea, but probably not.

There are several good reasons for not doing it (the RIAA equalization will be messed up, improper earthing of the equipment, serious signal level mismatch if a phono pre-amp is not used, reduced bass response...)

If you were to try it, you would need to run a reverse RIAA curve filter to remove the RIAA filter effect of the pre-amp, then speed it up, then run the correct RIAA filter.

I believe 'Noise Reduction' should be first, then 'DC bias removal',

Much of the work for a good recording comes before the stylus touches the vinyl. Ensure that the record is properly cleaned and the turntable, stylus, cartridge, tone arm and electrical connections are all in good order.

Check your recording level carefully. It is essential that the recording level never goes to 0 dB - always keep a little gap between the waveform and the top/bottom of the track even at the highest peaks (though for old records don't worry if there is an occasional pop or crackle that goes a bit too high - you will need to fix that later anyway)

If required, DC offset correction should be the first thing that you do after recording. The other tools will be much happier if they are not trying to cope with DC.

A rumble filter (low frequency high pass filter) is a good second step. The less work that you give to Noise Removal, the better it will perform.

Clicks, crackles and pops next.

Then, if required, Noise Removal - hopefully you won't need much of this once the other steps are done.

See also: http://manual.audacityteam.org/o/man/sa ... ation.html

[kozikowski]

And don't forget the velocity thing. Phono styluses are designed to vibrate really well at audio rates. Playing a record off-speed means the stylus will not accurately follow the lumps in the groove. The vibrations will either be too slow and the whole cartridge tries to follow the undulations instead of just the stylus, or too fast and the stylus glides right over some of the higher notes and in both cases the distortion and frequency response suffer.

Some styluses also have resonance lumps in their response curve -- generally designed to be outside the range of hearing. But not if you play off-speed.

Koz

[waxcylinder]

This article in the manual explains why you are advised not to do this: http://manual.audacityteam.org/man/High ... _transfers

WC

[JRSVader]

This article in the manual explains why you are advised not to do this: http://manual.audacityteam.org/man/High ... _transfers

WC

But I am doing the opposite, recording at a lower speed to get more samples per second. Since my stylus is designed for 33 1/3 albums I get distortion when I play 45 rpm vinyl without the larger stylus. So by playing the vinyl at 33 1/3 (the speed the stylus is designed to be used at) I get 35% more samples per second than if I played the record at 45.

I am going to correct the speed first then proceed as normal for the other hundreds of vinyl rips in my collection. I do have the original rip made at 45 rpm to compare with this project, so if there is a drastic difference I'll be sure to post it here.

[waxcylinder]

Yes but you will still get the RIAA equalization applied incorrectly by your preamp if you play the record at a lower speed.

The stylus for a vinyl LP should be fine for vinyl 45's - I certainly used the same one when I did my 45 conversions without any real problems (apart from the fact that many of my singles had had a very hard life on my old juke box leaving them with many pops and scratches). It's only for 78s that you should need a larger diameter stylus.

WC

[steve]

Since my stylus is designed for 33 1/3 albums I get distortion when I play 45 rpm vinyl without the larger stylus.

As waxcylinder wrote, the same stylus should be OK for 33 1/3 or 45.
45s are often cut a lot louder (bigger wiggles) than LPs, so the distortion is probably just due to the signal level being higher. Try turning down the volume at the first place possible in the signal chain, for example, if you can control the volume on the turntable, turn it down there (signal chain: stylus > cartridge > phono pre-amp > sound card > Windows sound system > Audacity > hard drive)

I get 35% more samples per second than if I played the record at 45.

Yipee, higher quality crackles

Seriously though, I think that it would be an interesting experiment. I doubt that the quality would benefit at all, and if it does then it is probably due to some fortuitous side effect rather than directly because of the slower speed. For example, at lower speed, the acceleration rate of the stylus is less, so the signal level should be less. The effect of RIAA equalization from the phono pre-amp being removed and then put back again, depending on the RIAA curves used, may have a net effect that is different from the phono pre-amp alone. I would expect that any subjective improvement (if any) could be more easily achieved by judicious use of the Equalization effect.