A Note on BeatmatchingThe Differences Between 45 and 33 & 1/3RPM RecordsA technics turntable has two different revolution speeds. 33 1/3 and 45 RPM (a.k.a revolutions per minute. This means that one full rotation takes approximately 1.80 seconds at 33 & 1/3RPM while a 45RPM is 1.33 seconds1 minute = 60 seconds60 seconds divided by 33.3 revolutions = 1.80 seconds60 seconds divided by 45 = 1.33 secondsRPMs are somewhat analogous to BPMs (beats per minute) but should not be taken into consideration when matching tempos between two tracks. The offset of a tracks BPM from 108bpms causes the spiraling texture you see on precisely looped or sincerely sequenced vinyl records. (i.e. dj scratchvinyl tools and many techno tracks.)On the topic of beatmatching, a technics turntable platter weighs 3.74 lbs. It is made of an aluminum diecast (hardened) metal that is 33.2 centimeters in diameter. These specifications have made the Technics SL-1200 model turntable the industry standard for the fact that the elapsed time of two tracks’ BPMs staying synchronized is much longer that other model tuntable’s torque/platter wieght characteristics.The quartz direct drive motor also makes the SL-1200 turntable an industry standard instrument. The accuracy of the capstan motor in correlation to the pitch adjustment slider allows smaller increments of pitch adjustment to be made. (This capstan motor is synced with the player’s 120V/ 60Hz power supply you get from your United States wall outlet, so make sure you are getting clean power!) This means that even though most turntables offer a pitch adjustment of (+8%) or (-8%) RPMs, the incremental value of pitch adjustment is more intricate and accurate on the SL-1200 models. I often dislike players with digital pitch conversion because the incremental values are “snapped to” or stepped. This subject matter can be likened to the digital pitch display on cd player that offer pitch bend. Some units only increment by a decimal place of .01% while some offer .001%. Here is an example of two models’ pitch adj. incremental values:Numark CDN25 pitch increment:= +1.6%Pioneer CDJ1000MK2:= %1.64The Pioneer model would allow better accuracy in adjusting/matching BPMs between two tracks.I have noticed that when matching a track’s BPM that was recorded at 33&1/3rpm with a track that was recorded at 45rpm, you must take into consideration the change in “pitch increment”.When a record is pressed, a master first needs to but “cut” by using a “reversed” phonograph cartridge , or lathe, (imagine a sylus that vibrates as if it were being stripped through a groove on a record, but instead being reallly hot and pulsating by itself on vinylite compound) These groove are cut at a 45/45 degree angle used to encode stereo audio within a groove shown here:

Left channel signal are cut into the inner wall of the groove and right channel signal are cut into the outer wall. The stylus motion is phased so that a signal that is in phase in both channels (mono) produces a lateral motion of the groove. Out of phase channels produce a vertical motion, or changes in groove depth. (This is why if a track is pressed with too much low end sub bass in stereo channel a stylus can literally be popped out of a record’s cut groove because of a thumpin kick drum.) Vinyl thickness imust also be taken into consideration because too deep of a cut groove on one side can actually be heard at a quite break of the track on the other side!Under a magnifying glass, you can actuall follow a waveform cut into a record. The groove much resembles the audio waveforms you see in many audio editing software...only on a microscopic scale. A waveform on a record that was cut at 33 &1/3 RPMs would look like this:

These cutting speeds have similar a similar affect to how a reel-to-reel tape machine yields certain differences when recording at different speeds(inches per second)The revolution speed of the platter determines the upper-frequency content of a track. The higher the speed, the higher the upper frequency limit. That same recording cut at 33 & 1/3 RPMs would yield better dynamic range. (signal to noise ratio with the added concept that a -6db per octave output reduction occurs for every doubling of a waveform’s frequency in correlation to your stylus’ physical characteristics (meaning that on a microscopic scale, the very tip of a stylus can only move so fast before it physically cannot reproduce the groove its being given---if one exists!) What can the best possible stylus reproduce? Something so tiny and small...how fast can it reproduce one 360 degree cycle?? or...how fast can a molecular atom’s electron change from a positive state, to a negative state, and back to a positive? Some people would theoretically say it’s “infinite” but there has to be a limit to how fast molecular atoms can physically change “polar” states. This can be likened to “the sampling rate of the universe.”Taking into consideration the groove differences of records cut at different speeds, you can use the acknowledgement upon matching the BPMs between tracks. When mixing a track pressed at 33 & 1/3 RPMs into a track of 45RPMs, a change in pitch bend is not linear to the change in pitch you would normally make when mixing tracks cut at the same speed. Moving the pitch adjustment slider down 1 point while playing a track cut at 33 & 1/3RPM has a bigger affect on BPM that a 45RPM. Inversely, you could say that a record cut at 45 RPMs has better incremental control over BPM. A track pressed at 33 & 1/3RPMs has better dynamic range, a wider range of pitch adjustment, more recording time, but less control over BPM. 45 RPM records have a higher upper frequency limit and better control over increments of BPM, but a smaller range of overall pitch adjustment with less time available to record on a side.Since you have more control over the increments of BPM on a 45... when blending into a track cut at 33 & 1/3RPM, use the turntable playing the 45 record to “fine tune” your pitch. Similarly, when mixing into a 45RPM with a 33 & 1/3RPM, do a generic beatmatch between the two and then switch to the turntable with the 45RPM to fine tune. Switching to the player with a 45RPM will give you better incremental control while you can use the 33 & 1/3RPM as your basis to match to. A 45RPM rotates .40 times faster than a 33 & 1/3RPM, so make the adjustment when your beatmatching one to a 33 & 1/3RPM!DJing is an art but I like to make it a science...Wes Clay