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R/E/P => Mastering Dynamics => Topic started by: Thomas W. Bethel on July 18, 2014, 09:14:55 am

Title: What causes low frequency bumps in vinyl record playback.
Post by: Thomas W. Bethel on July 18, 2014, 09:14:55 am
If you look at a vinyl record playback on an oscilloscope set for phase display certain records cause the display to jump vertically. If you filter out any information below 20 Hz by using a high pass filer the oscillations pretty much go away. These bumps seem more noticeable on records that were not made by main stream record companies. I am wondering if this is due to a lathe that has bearing problems or a platter that is not true on the lathe or if these bumps are caused in the plating or pressing of the record? Any help in learning about these would be most welcome.

Thanks in advance!
Title: Re: What causes low frequency bumps in vinyl record playback.
Post by: Greg Reierson on July 18, 2014, 10:50:04 am
All of the above. It would take a close inspection of the vinyl to give clues and even then you may never know the cause. Can you post a sample?
Title: Re: What causes low frequency bumps in vinyl record playback.
Post by: dany500 on October 10, 2014, 05:05:26 pm
It would take a nearby investigation of the vinyl to give pieces of information and still, after all that you might never know the reason. Can you post a specimen?
Title: Re: What causes low frequency bumps in vinyl record playback.
Post by: polypals on October 10, 2014, 06:41:12 pm
The quality of the lathe used to cut the record may certainly be part of the problem.

Do not rule out external influences at the time the record was cut.

On a number of the famous Decca SXL series of classical music low frequency noise can be traced that is caused by London Transport.
The cutting rooms were located in a building close to a bus line in London.
Title: Re: What causes low frequency bumps in vinyl record playback.
Post by: aleeza on December 30, 2014, 01:27:07 am
nice and good post
Title: Re: What causes low frequency bumps in vinyl record playback.
Post by: ericp20 on May 04, 2015, 08:25:24 pm
too interesting, very good