Subject:Recording LP at 78RPM quality

Posted by: Lanco

Date:3/13/2005 2:09:31 AM

Hello

Has anyone recorded an LP at a faster rate such as 78RPM?

If so, how does it work out? Does it sound as good as if recorded at 33.3?

What method did you use? There must be some kind of formula to figure this one out.

Any help appreciated.

Scott

Subject:RE: Recording LP at 78RPM quality

Reply by: sirshambling

Date:3/14/2005 9:30:47 AM

No - but recording 45s at 33 sometimes helps if the single is warped, jumps etc.

John.

Subject:RE: Recording LP at 78RPM quality

Reply by: kbouchard

Date:3/14/2005 6:06:26 PM

Scott,
Check out this guy's site under "special cases".In my business, I occasionally slow down a 78 to 33.3 so I can restore it.
NOTE: This only works if you've got a soundcard that supports alternate sampling rates.

thanks, ken

http://www.a-reny.com/iexplorer/restauration.html

Subject:RE: Recording LP at 78RPM quality

Reply by: Lanco

Date:3/15/2005 6:19:06 PM

For anybody wanting to easily record a record at one speed and then change that speed, I discovered that Audacity will do it without any math formulas. Just set the two speeds, from one to the other and there it is.

My thought was that perhaps I can record an LP at 78 and bring it down to 33.3. Thinking it might be a quicker way to record and get the same results.

So, I tried playing an LP at 45, 78, and 33.3 while recording. I then brought the 45 and 78 recordings back to 33.3.

While the pitch is absolutely perfect along with the speed, there seems to be a little sound degradation when doing this. I might want to try doing this again with different combinations of recording.

I also remember a few years ago, I tried the formula to record a 78 record at 33.3 or 45 and found that it does not sound exactly like it does at 78 rpm.

I have about 25 turntables (plenty of spart parts, lol) with 33, 45 and 78 speeds, so it does make a difference here if you want to split fine hairs.

I would say that if someone wanted to use this process going in either direction, unless you had a side by side comparison, that it would be fine to most peoples ears.

Subject:RE: Recording LP at 78RPM quality

Reply by: John 17:17

Date:3/16/2005 12:40:58 AM

Yes, there is a difference, scientifically. If you know anything about musical instruments you'll understand. Musical instruments are in different keys for this very reason: they don't all sound the same. When a trumpet plays an Eb, that sound will be distinct, and you can't reproduce it by having the trumpet play any other note and then using a computer to bring it back to an Eb. In other words, if you speed up the record, then instead of the trumpet playing an Eb, it will be playing, say, an Ab (and not a true Ab at that), and then if you lower the pitch in SF back to Eb, it will not sound the same as if you recorded it playing the Eb to begin with. The purists will tell you to record it the way it was meant to be played and heard the first time. Make sure the record is totally clean with mild soap and filtered, lukewarm (not hot, as that will warp the lp) water and that the needle tracking is not too light (as that will pick up every possible click and crackle), and not too heavy, either, (as that will dig into the groove too deep and cause unnecessary distortion). (Clean your needle with alcohol after every side of play--you'd be surprised how quickly they get grimey--use a good loupe to inspect for wear.) I'd give suggestions as to the world's best restoration software but I don't think I should on a Sony forum. :)

Subject:RE: Recording LP at 78RPM quality

Reply by: jtuffen

Date:3/16/2005 3:05:57 AM

I feel that if you're slowing down/speeding up records, you need to compensate for the RIAA Equalisation curve which is built into the phono pre-amp...

I can't remember the specifics of the curve, but it basically boosts the bass end of the frequency spectrum. Obviously if you're playing a record at a slower speed, the mid-frequencies will be lowered, and hence may be boosted by the RIAA Equalisation filter; subsequent speeding up of the sound file will result in the mid frequency being louder than intended...
... same goes for recording vinyl at a faster rate (only the low frequencies would sound quieter in comparison to the original vinyl played at the correct speed).

I intuitively think that this would be the workflow:
1) Record sound from turntable at higher/lower speed (whatever);
2) Apply an inverse RIAA curve on the recorded file;
3) Speed up/slow down as appropriate (factor of 78/33.3, 33.3/45, or whatever is appropriate!);
4) Apply the RIAA curve to the final file.

Of course, I've never done this (always transfer recordings at the correct RPM!) but it seems like the correct way to deal with the speeding up/slowing down being talked about here.

john..

Here's a link to a discussion of the RIAA curve...

Subject:RE: Recording LP at 78RPM quality

Reply by: colinu

Date:3/16/2005 6:11:12 AM

I sorta understand what you are saying, and it reminds me of the story of Roxy Music's Avalon SACD. Apparently the analog multitracks were in bad shape (as unfortunately are many tapes of this era). The 5.1 mix was created from a mutlitrack digital copy of the original done some years ago - but the original was running too fast at the time of transfer. The copy was 16bit 48khz, and they changed the sampling to bring it down to the proper speed, but give a higher resolution. Wouldn't this technique also bring about the change you talked about?

Subject:RE: Recording LP at 78RPM quality

Reply by: mpd

Date:3/16/2005 6:59:02 AM

I think you are right about the RIAA curve. The record any playback curves are inverses of each other so that the end result is a flat spectrum. The standard playback curve boosts the low freqency, and also cuts the highs. If you playback at a different speed then the effected bands will be different.

I am starting to work on my own DX and VST plugins, and will be offering most of them for free (at least initially). RIAA playback EQ is on my todo list. Creating versions for different playback speeds isn't that hard if you know DSP theory. I'll post something when I have something ready to test.

Subject:RE: Recording LP at 78RPM quality

Reply by: jtuffen

Date:3/16/2005 7:35:12 AM

(I'm at work so I can't check but...) isn't there a RIAA curve preset on one of the Sound Forge EQ plugins?

john..

Subject:RE: Recording LP at 78RPM quality

Reply by: Lanco

Date:3/17/2005 3:21:54 AM

Hi John

I have SF5.0 and I'm quite sure there is no Riaa curve present.

I am also aware that a lot of SF users do some editing in other programs, so I guess it's ok to mention the free Audacity program.

Under Effects-Equalization they have the following curves as presets:

Acoustic
AES
RIAA
EMI78
NAB
Decca FFRR Micro
Columbia 78
RCA Victor 1938
Columbia LP
Decca FFRR 78
Decca FFRR LP
RCA Victor 1947

Best

Scott

Subject:RE: Recording LP at 78RPM quality

Reply by: captn_spalding

Date:3/17/2005 10:12:16 AM

Right up front I have to say I don't understand why one would play lp's at 78 rpm. I do quite a bit of audio restoration and when I'm doing LP's i'm listening very carefully and dropping markers at potential trouble spots as I record into sound forge. But, be that as it may, here are some issues you have to address:

1. If you are playing back thru a preamp with RIAA equalization, your recordings are being mis-equalized (as has been pointed out above). Therefore, you need a preamp that is flat. Such as:

http://www.tracertek.com/ctp1000.htm

2. Now that you have your unequalized, flat version of the sound on the LP and after you have re-corected the speed, you could use DC Six for the RIAA equalization. For just audio restoration it is perhaps the best , reasonably priced software on the market:

http://www.enhancedaudio.com/dc_six.htm

3. Then there is the issue of the sylus/cartridge and its frequency response. I havent looked, but what was 15khz coming off of the lp is now 35.5 khz. Is your cartridge flat up in that region?

4. Which leads to tracking force. When I'm doing restoration one of my golden rules is: Don't do anything to degrade the original media. With the stylus flying 2.6 time faster than it was designed to, and being asked to track frequencies higher than it was designed to, you will have to increase the stylus pressure. Thus the soft vinyl is being attcked by a diamond stylus traveling much faster and with much more force than it was designed to do. A 78 rpm record has a groove at least 3 times as wide as an lp groove and therefore the higher tracking pressure is being distributed over a larger area by the larger 78 rpm stylus

Anyway, good luck with your project


..spalding