scratching in key explained

[agentkaos]

hey guys, nice forum.

my first post - using the turntable to scratch in key...

to increase or decrease the pitch by 1 semitone you need to apply +/- 5.945% of speed.

by changing the pitch on a turntable by +/- 6% you will effectivly pitch the song up or down 1 semitone.

ok, so from this we can say...

if the record is spinning at 33.3rpm and then the speed is changed to 45rpm, the platter will speed up by 35%.

a 35% increase in speed will result in raising the pitch by 5 semitones and 20 cents.

so, if for example the pitch is middle C and the speed is 33.33rpm, then by changing the speed to 45rpm you change the pitch to F (plus 20 cents).

i found that if the speed of 44rpm had been adopted (which is wasn't) then changing from 33.33rpm (C) to 44rpm would of changed the pitch to F minus 19 cents. This is musically closer to a perfect fifth, but only by a bees dick... The following is an explanation of why 45rpm was chosen...

'The 45 rpm speed was the only one to be decided by a precise optimization procedure (by RCA Victor in 1948). Calculus was used to show that the optimum use of a disc record of constant rotational speed occurs when the innermost recorded diameter is half the outermost recorded diameter. That's why a 7-inch single has a label 3 1/2 inches in diameter. Given the CBS vinyl groove dimensions and certain assumptions about the bandwidth and tolerable distortion, a speed of 45 rpm comes out of the formula.'

excerpt from: http://www.history-of-rock.com/record_formats.htm

interesting - but would of been way cooler if they'd used 44.5rpm - because this would of lifted the pitch up a perfect. perfect fifth.

if the note C is playing whilst the turntable is spinning at 33.33rpm, then just by using the turntables pitch control you can play the following notes...

B > 33rpm > -6%
C > 33rpm > 0%
C# > 33rpm > +6%

E > 45rpm > -6.5%
F > 45rpm > -0.5%
F# > 45rpm > +5.5%

if you were jamming with a song in B minor, the notes you could play that are in that scale would be: B, C#, E & F#.

so in B minor you can play:

* the root > B
* major 2nd > C#
* perfect 4th > E
* perfect 5th > F#


Ran a search and here are some songs in B minor:

* Hotel California - The Eagles
* Comfortably Numb - Pink Floyd
* Korn - Love Song
* Hey Bulldog - The Beatles
* I Just Died in Your Arms - The Cutting Crew
* If You Had My Love - Jennifer Lopez
* Juke Box Hero - Foreigner
* Makes Me Wonder - Maroon 5
* Maneater - Daryl Hall & John Oates
* Pinball Wizard - The Who
* Wicked Game - Chris Isaak
* Money - Pink Floyd

Also - remember that B minor's relative major scale is D major. This means that you can use those same 4 notes except they're now:

* major 2nd > E
* major 3rd > F#
* major 6th > B
* major 7th > C#


Some songs in D major include:

* Ice Ice Baby - Vanilla Ice
* New York, New York - Frank Sinatra (changes to E-flat)
* I'd Do Anything For Love (But I Won't Do That) - Meat Loaf
* Sweet Home Alabama - Lynyrd Skynyrd
* Crazy Little Thing Called Love - Queen
* Every Little Thing She Does Is Magic - The Police
* Girlfriend - Avril Lavigne
* I Can See Clearly Now - Johnny Nash
* I Don't Wanna Miss a Thing - Aerosmith
* I'm Your Man - Wham!
* I Don't Feel Like Dancin' - Scissor Sisters
* Jingle Bell Rock - Bobby Helms
* Just the Way You Are - Billy Joel
* Kung Fu Fighting - Carl Douglas
* Lithium - Nirvana
* Mamma Mia - ABBA
* My Way - Frank Sinatra
* One Angry Dwarf and 200 Solemn Faces - Ben Folds Five
* She Drives Me Crazy - Fine Young Cannibals
* Should I Stay or Should I Go - The Clash
* Shy Boy - Bananarama
* They'll Need A Crane - They Might Be Giants
* Tubthumping - Chumbawamba
* Twist and Shout - The Beatles
* Ventura Highway - America
* Wake Up Little Susie - The Everly Brothers
* Waterloo - ABBA
* Where the Streets Have No Name - U2

ohhh yeh - d major rules.


serato scratch 1.8 came out last week and with it midi compatability. This is cool because you can map your mpc or midi keyboard to any of serato's funtions. serato has the ability to set 5 cue points per digital music file. You can map, then trigger these cue points with your midi device. this means that as you hit a note on your keyboard, it'll jump to a particular cue point on the record.

so, you can use your music sequencer of choice to make up a .wav file that includes the following notes:

* C
* D#
* F#
* A

make the notes long - like 5 seconds or longer (a minute upwards per note is totally fine). Using serato, setup a cue point at the start of each note - then map the 'play from cue point' buttons to 4 keys on your midi keyboard.

put serato in relative mode and start your record. the first note will play and you can scratch and pitch it. hit the notes you mapped on your midi keyboard and you'll jump to the new notes - no latency. basically feels like using a sampler, but you have the benefit of being able to scratch, pitch and cut all the audio as well.

so - to get the full octave, you use the pitch control (+/-6% on 33rpm) to get the missing semitone on each side of your notes...

if you use the 45rpm speed to alter your pitch, and then the 5th cue point in serato you can get a bit over 2 full octaves.

also because i love serato i'll mention that the new rane ttm57 mixer with serato built in has video support so you can scratch the video along with the music - makes sampling much more interesting...

[admin]

Thanks for that post, agentkaos

A real neat explanation in terms of 'scratching'! I'm sure lotta DJ's aboard audioHOLICs.org will be benefited by this.. Psst. This includes me as well! Well, a DJ by passion and interest!
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Cheers...
Sudarshan
Board Admin - audioHOLICs.org Admin
www.theaudioholic.com