Hi,
I ripped my vinyl collection. On playback I notice fluctuating BPM.
I ripped using a direct drive , rubber mat and weight.
Does vinyl play, did it always play with a mild fluctuation, 0.01, 0.02 etc?
Is there a way of making the BPM consistent in the track? If so, is this perfect or what side effects occur?
Thanks in advance!
Nick
I ripped using a direct drive , rubber mat and weight.
Unless there’s something wrong your turntable it should be very stable. Unless maybe you’ve added too much weight? 
On playback I notice fluctuating BPM.
Are you also hearing a pitch variation? When the speed changes, pitch and tempo change together and the pitch variation usually more noticeable. Slowly-varying speed is called “wow” (more common in turntables) and faster variations are called “flutter” (more common in tape recorders.) Audible wow & flutter are usually caused by a worn belt or drive wheel, but a direct-drive turntable doesn’t have those.
Or you can get wow if the hole in the record isn’t perfectly centered.
- Does vinyl play, did it always play with a mild fluctuation, 0.01, 0.02 etc?
0.01 or 0.02 what beats per minute? That’s not much variation!
If it’s just the tempo and not a speed problem… Musician’s aren’t perfect and some songs intentionally have tempo variations . Most modern recordings are made with a “click track” (metronome), but not all recordings. With older recordings it was usually up to the band leader or drummer to hold/control the tempo and two or more takes won’t exactly match in tempo.
Hi, thanks for replying.
This came about from DJ mixing the tracks and I noticed the change at that point. Where even though the tracks were initially in sync and playing at the same speed, I then noticed they moved off the sync. No noticeable tone shift.
Tracks are analysed with software before using and if I use dynamic it shows constant minor fluctuations on the BPM.
Is original vinyl never at a dead set bpm, playing on a turntable? Is this just a true representation of how it was?
DJ decks typically have variable speed, and may use “slipmats” rather than the rubber mat typical on hi-fi record decks, both of which could contribute to variations in tempo. If it’s not an audible distraction to enjoyment of the music, then it’s not really a problem is it?
Where even though the tracks were initially in sync and playing at the same speed, I then noticed they moved off the sync. No noticeable tone shift.
Two different turntables playing two identical records?
Tracks are analysed with software before using and if I use dynamic it shows constant minor fluctuations on the BPM.
Software for BPM detection is imperfect. That might be what you’re seeing,
Is original vinyl never at a dead set bpm, playing on a turntable?
Nothing is perfect. Like I said, the music itself may not have perfectly-constant timing. i.e. Live music rarely uses a click track so it usually varies. MIDI or other computer-generated music can have nearly-perfect timing. (MIDI instruments can also be played by humans.)
A direct drive turntable with “locked” speed usually has a quartz clock (time reference) and they should be very good. A turntable with variable speed may not be as accurate.
There were older belt drive turntables that used synchronous motors (like what’s used in electrical plug-in clocks). These lock-into the power line frequency which is super accurate in most countries.
BTW - Digital isn’t perfect either, usually it’s fairly stable. The sample rate clock (i.e, 44.1 kHz) isn’t always “perfect” and any difference will cause a pitch and tempo change. Some musicians have trouble when they record with one device (like a USB microphone] and then play-back on a different device (like their soundcard). Soundcards also use a quartz crystal but some consumer soundcards are pretty bad. The same issue could show-up if you record from a USB turntable and then play-back the digital copy from your soundcard. Pros use a vary accurate (and very expensive) master clock and equipment that’s designed to work with an external master clock.
P.S.
In music production the important thing is that the tempo of various parts/instruments match. If the band plays a little fast one time and a little slow the next time, or if the beginning of the song is a little slower than the end, that’s not a problem* as long as everybody is playing together. If a vocal track and guitar track are recorded at different times (very common), nobody says “play or sing at 100BPM”. Usually one performer goes first and the other(s) listen to the backing track with headphones while playing back in-time with the backing track.
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The sample rate clock (i.e, 44.1 kHz) isn’t always “perfect” and any difference will cause a pitch and tempo change.
Absolutely.
That clock is derived (normally via a PLL and dividers) from a master clock on the motherboard.
Of course, these vary in quality (read stability) and thus have a direct impact on recordings.
To compound things, clock sources can suffer from short term and/or long term drift (and jitter), due to temperature,
voltage fluctuations and or just plain old inferior components.
As DVDdoug wrote, if you want very good precision and accuracy, you will need lots of $$$ to get professional grade clock sources.
An example of this, is the master synch generator at TV stations.
Thanks for the replies.
The recording was done to digital, with a rubber mat etc. but maybe these records were never a 0.00 accuracy regardless of anything else.
Then going through more software to go on digital players I guess there are lots of areas for little holes of bpm creep.