BPM V's RPM

Post: # 19761Unread post **aussie cutter** Sat May 19, 2012 11:42 pm

Hi all,

Just wondering if there is a general rule to cutting when it comes to bpm v's rpm?

Of late i've been doing a bit of test cutting to tune up my presto lathe and i have found that if the source material is 128bpm or higher - i get better results when i cut at 45 instead of 33 1/3...

When i cut at 33 1/3 the sound/tone is deeper & bassy than the original source - when i cut at 45 it sounds the same as the source...

I am accounting for the mechanical weight of the lathe as well as the drag created by the cutterhead by speeding up the turntabe and setting the strobeoscope & upon playback of the cut material the bpm stays true...

A simple laymans explaination would be much appreciated...

Post: # 19764Unread post **andybee** Sun May 20, 2012 6:07 am

at 33 RPM, the groove (one cycle) is much shorter, and especially at inner diameters the frequency response at trebles is not good anymore.
reducing the volume can help a bit...
this is my experience, but this physical effect has nothing to do with the BPM.

Post: # 19766Unread post **petermontg** Sun May 20, 2012 6:29 am

Sorry, read your post wrong.

Post: # 19767Unread post **Angus McCarthy** Sun May 20, 2012 6:48 am

It could have to do with faster-tempo'd songs often being "louder" in general.

Post: # 19769Unread post **aussie cutter** Sun May 20, 2012 8:35 am

Angus McCarthy Wrote: It could have to do with faster-tempo'd songs often being "louder" in general.

Hmmmm! this sounds sort of on the right path to what i have noticed...

To describe it simply - It's sort of the same effect that happens on a DJ CDJ when you set the bpm and don't use the master tempo control - the played sound becomes droopy or chipmonk like depending which way the bpm is set (slower or faster)

Admittedly i have only been using a couple of new age hard dance tracks to test with - I should expand the range a bit with bpm and styles and see if this happens across the board or not...

I've also just recorded some test tones and sweeps off the net - I have to check them over and maybe adjust the volume levels on them before using on the lathe - should be interesting...

Post: # 19770Unread post **Angus McCarthy** Sun May 20, 2012 9:41 am

Try doing a test cut of Robert Miles against a test cut of Skrillex. Same BPM, very different "loudness" level.

Post: # 19788Unread post **aussie cutter** Sun May 20, 2012 7:03 pm

Thanks for the suggestion Angus. I actually have robert miles on vinyl "Children Rocks! - I have also got adolesence too"... I had a quick listen to skillrex (I get where ya coming from) completly different feel to them, One has more energy the other one has less - I guess in future I'd just have to be mindful and preview the track before determining weather to cut 33 1/3 or 45

I Love this site - Learning more and more everyday!

Post: # 19801Unread post **Aussie0zborn** Mon May 21, 2012 8:14 am

aussie cutter wrote: - It's sort of the same effect that happens on a DJ CDJ when you set the bpm and don't use the master tempo control - the played sound becomes droopy or Chipmunk like depending which way the bpm is set (slower or faster)

Sounds like you're talking about a change in pitch, which is waht happens on a DJ CD player when you change the pitch without using the "Master Tempo" control at the same time.

Disc cutters never consider the BPM of a song for any purpose. Its always about the best way to fit the song into the confines of a vinyl record.

Post: # 19831Unread post **aussie cutter** Tue May 22, 2012 2:53 am

What ever the true name of it is.. (Pitch, tempo etc...) it seems that some tracks just prefer to be cut at 45 instead of 33 1/3 - No biggy really, just a good learning curve for me...

I was doing some more test cutting and tuning of the lathe today & had a friend over who stuck around to see it all happen , he was blown away to see what is really involved in obtaining a decent cut...