It’s a compromise between dynamic range versus playing time.
When a record mastering engineer cuts the the stamping master, he has to limit lateral cutter stylus movement while maintaining adequate groove spacing which in turn affects the amount of play time on the record.
The RIAA equalization curve was originally invented to reduce the bass frequency amplitudes during mastering (and emphasize the treble frequencies) exactly for this reason so that on playback with the reverse equalization you get "rumble" noise and almost non-existent hiss noise.)
Dynamic range compression is often applied in order to fit more music onto a side of the record.
If the engineer can cut the record with less playing time per side (i.e. a 12 inch record with only 3 songs instead of 5) then he can afford to allow greater lateral cutting stylus movement and thus greater dynamic range but only up to a limit before it can potentially skip on some record players (hence the evolution towards high-compliance light tracking force needles).
A great example of this was Led Zeppelin II LP there is a now rare and highly-sought after commercial "hot" print with very high dynamic range but it skipped on some record players and got recalled and was remastered with lower dynamic range and better trackability at the expense of sound quality.
At the opposite extreme were those 1980s K-tel compilations records where they could fit 8 to 10 songs per side but they sounded flat like AM radio due to extreme dynamic range limiting to maximize playing time.
The 45 rpm speed will minimize the phenomenon of "inner groove distortion" since the groove speed as seen by the needle slows down as the record plays from outside to inside. It’s caused by the cutting needle physically deforming the track behind it because the groove speed is too slow and has been a known problem since the 33 RPM LP was first invented and one of the reasons the first records were cut at 78 RPM.
Spinning the record at 45 PM practically eliminates inner groove distortion and on a 12" disc it’s mostly using the outermost track area with the highest available groove speed.
Of course the down side is that you have to flip the record over more often which *IS* distracting.
Personally I happen to think those 45 PM 2 disc 12 inch re-releases don’t’ make sense!
For my money if I really cared about maximizing sound quality I’d just buy the CD release - no need to deal with limited dynamic range, surface noise or the need to interrupt the listening experience to flip or change the record - just pure music enjoyment.
Besides many vinyl records are cut from digital master tapes now unless they say specifically that it was cut from the original analog 30 IPS studio master tapes.
When a record mastering engineer cuts the the stamping master, he has to limit lateral cutter stylus movement while maintaining adequate groove spacing which in turn affects the amount of play time on the record.
The RIAA equalization curve was originally invented to reduce the bass frequency amplitudes during mastering (and emphasize the treble frequencies) exactly for this reason so that on playback with the reverse equalization you get "rumble" noise and almost non-existent hiss noise.)
Dynamic range compression is often applied in order to fit more music onto a side of the record.
If the engineer can cut the record with less playing time per side (i.e. a 12 inch record with only 3 songs instead of 5) then he can afford to allow greater lateral cutting stylus movement and thus greater dynamic range but only up to a limit before it can potentially skip on some record players (hence the evolution towards high-compliance light tracking force needles).
A great example of this was Led Zeppelin II LP there is a now rare and highly-sought after commercial "hot" print with very high dynamic range but it skipped on some record players and got recalled and was remastered with lower dynamic range and better trackability at the expense of sound quality.
At the opposite extreme were those 1980s K-tel compilations records where they could fit 8 to 10 songs per side but they sounded flat like AM radio due to extreme dynamic range limiting to maximize playing time.
The 45 rpm speed will minimize the phenomenon of "inner groove distortion" since the groove speed as seen by the needle slows down as the record plays from outside to inside. It’s caused by the cutting needle physically deforming the track behind it because the groove speed is too slow and has been a known problem since the 33 RPM LP was first invented and one of the reasons the first records were cut at 78 RPM.
Spinning the record at 45 PM practically eliminates inner groove distortion and on a 12" disc it’s mostly using the outermost track area with the highest available groove speed.
Of course the down side is that you have to flip the record over more often which *IS* distracting.
Personally I happen to think those 45 PM 2 disc 12 inch re-releases don’t’ make sense!
For my money if I really cared about maximizing sound quality I’d just buy the CD release - no need to deal with limited dynamic range, surface noise or the need to interrupt the listening experience to flip or change the record - just pure music enjoyment.
Besides many vinyl records are cut from digital master tapes now unless they say specifically that it was cut from the original analog 30 IPS studio master tapes.