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33 1/3 rpm definition- urgent!

Discussion in 'Recording' started by lelijaa, Sep 8, 2016.

  1. lelijaa

    lelijaa Active Member


    I'm a completely vinyl beginner and I'm trying to find on the web some answers to my question but I can't find anything that helps me to understand it completely..
    So, can anyone please explain me what does "33 1/3 rpm" actuallly mean? If I'm told to give audio materials for cutting in "33 1/3" (I'm recording in Ableton) does that mean the audio should be in 133 bpm or something else?

    Please help me to understand this better.
    I appreciate any help!

  2. Boswell

    Boswell Moderator Distinguished Member

    33 1/3 revolutions per minute (rpm) is the rotation speed of the vinyl on the turntable - you should not have to carry out any operations relating to that when preparing your files.

    You need to send the cutting house a mastered stereo .bwav or .wav file. This is usually at 24-bit 48KHz, but check with the cutting house what they would prefer, e.g. CD standard 16-bit 44.1KHz.
  3. DonnyThompson

    DonnyThompson Distinguished Member

    33 1/3 is the speed at which the disc (LP album) rotates on the turntable. It means that the album rotates 33.3 times per minute. It has nothing to do with the audio you want to have cut to the disc.

    You supply the finished mixes in whatever format the disc cutting facility requires.
    This refers to the type of file you save the song to ( wav, flac,) whether the audio is stereo or mono, and at the sampling rate and bit resolution that they ask for.

    You should contact the disc manufacturer and ask them what they want in regard to the above.

    As a final note, and no offense intended, you sound like you may be in over your head with this. Mixing for vinyl isn't any different than mixing for digital, but Mastering audio for vinyl differs quite a bit from that of mastering for CD or digital streaming. You may want to contact a mastering engineer who specializes in prepping audio for vinyl. If the disc cutting facility is doing the mastering, then you need to contact them and find out exactly what they need.

  4. lelijaa

    lelijaa Active Member

    Thank you! I understand now what rpm actually means.

    Yes, I know that mastering for vinyl is a bit different then mastering for digital or cd, but I just need to send audio material to mastering engineer. I will contact him then for more details. Thank you!
  5. Kurt Foster

    Kurt Foster Distinguished Member

    oy vey! i feel so old!
    Sean G likes this.
  6. dvdhawk

    dvdhawk Well-Known Member

    Crank up the Victrola Kurt and get out your 78s.
    Sean G likes this.
  7. Kurt Foster

    Kurt Foster Distinguished Member

    laugh if you want to . i do have some 78's. one is a very cool pressing of Lefty Frizzell's "I love You a Thousand Ways".
    dvdhawk likes this.
  8. DonnyThompson

    DonnyThompson Distinguished Member

    I have a crate of Edison CYLINDERS. ;)
    dvdhawk likes this.
  9. dvdhawk

    dvdhawk Well-Known Member

    I had some 78s, but I don't think they're still around. Somewhere around here I've got a stylus from a gramophone, which if I'm remembering correctly, was nothing more than about an inch long piece of steel that tapered to a sharp point.

    I'm finding it hard to believe that in all of the internet, the answer to the OP's 33 ⅓ rpm question couldn't be found in great/excruciating detail.
  10. Kurt Foster

    Kurt Foster Distinguished Member

    33 & 1/3 is also the title of a really great George Harrison album ...... and yes i do have a copy of that on vinyl as well. i gotta start getting rid of all this stuff.
  11. dvdhawk

    dvdhawk Well-Known Member

    But the OP did get me thinking, because I'm just a fool for this kind of mental exercise, (as opposed to actual, physical exercise)…...

    If everything were perfectly accurate, and you threw a 4/4 alternating kick & snare beat on a 33 1/3 LP, with a BPM of exactly 133 1/3; wouldn't that put the 1 (kick) of every measure at 0˚, the 2 (snare) at 90˚, the 3 (kick) at 180˚, and the 4 at 270˚ ? And since the RPMs are constant, would that pattern hold over the radius of the entire disc?

    I'm figuring at 133 1/3 BPM there's a beat every .45 seconds, which I figure is how long it takes the disc to turn exactly 90˚ - regardless of the constantly shrinking diameter the stylus follows as its being played.

    Anybody else want to play, or school me? I'm stuck, and trying to see what I'm probably missing.

    @DonnyThompson, sorry for the tangent. The OP got their answer straight-away, so I don't think they're coming back to revisit the topic.
  12. DonnyThompson

    DonnyThompson Distinguished Member

    LOL. Me too. Crackerbox Palace is my favorite track on that album, still love that song to this day. It's in my top three of favorite GH songs.
  13. R1N Recording Studio

    R1N Recording Studio Active Member

    Great, thanks. No sleep for me now.
  14. dvdhawk

    dvdhawk Well-Known Member

    If you come up with something different, please share your math!

    I figure:

    RPM to Degrees Per Minute
    33 ⅓ Revolutions Per Minute = 12ooo degrees of rotation per minute
    12000 degrees / 60 seconds = 200 degrees per second

    Seconds Per 90 Degrees of Rotation
    The target of 90 degrees rotation / degrees per second (200) = .45 seconds (90/200 = .45)
    The target of 180 degrees rotation / degrees per second (200) = .9 seconds (180/200 = .9)

    BPM to Beats Per Second
    60 seconds / 133 ⅓ beats = 1 beat every .45 seconds

    The way I see it, time is the constant, so if the BPMinute is exactly 4x the RPMinute, then there should be a beat at exactly every quarter rotation.

    However, the drums would lose fidelity as they progressed toward the center of the LP, just due to loss of frequency response inherent in the loss of relative 'speed'.

    Bonus question: How many grooves would be on this 40-minute LP?
  15. paulears

    paulears Well-Known Member

    Just the one!
    Kurt Foster likes this.
  16. dvdhawk

    dvdhawk Well-Known Member

    I was thinking two. One on each side, but the question was arguably vague. Points for Paul!
  17. paulears

    paulears Well-Known Member

    Actually - I'm old enough to remember people being very vocal about this when records were still the primary media. How many grooves per inch? There were those compilation records that had loads of tracks that squeezed far more grooves into an inch, and then the signal to noise was much worse as you had to turn the volume up. Then the 80s came along with BIG bass, and even budget hifi systems started to need better turntable arms to keep the stylus in the groove. Looking back, every recording had a different volume, and nobody complained - nowadays, with huge dynamic range, we have become obsessed with level management. Funny that!

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