# How many millimeters are in an octave?

#### Scott Baxendale

##### Most Honored Senior Member
Silver Member
Maybe rather than what country you live in, it should be artists use inches and engineers use metrics?

Wait is that like Mac vs PC?
It’s not a country thing. I know lots of guitar builders in the states who use metric measurements. For some strange reason I have always known that there are 28 grams in a ounce!

#### BuddhaFingas

##### Senior Stratmaster
Depends on which ounce, tho...

#### Delphic

##### Strat-Talker
Fender should change the scale length from 25.5" to 24".

Then frets could be exactly one inch apart.

#### Scott Baxendale

##### Most Honored Senior Member
Silver Member
Fender should change the scale length from 25.5" to 24".

Then frets could be exactly one inch apart.
A Fender Jaguar and the Duo Sonic both already have a 24” scale length. But if you know how scale length and frets work then you’d know that they aren’t equally spaced. Once you determine what scale length you use a factor to divide into that length. Say your scale is 24” then you take 24 inches and divided it by 17.817 which gives you a number which is the distance to the first fret. Then you subtract that number and then take the remainder and divide it again by 17.817 which gives you the distance from the first fret to the second fret. You keep repeating this process until you have the number of frets you want on your guitar.

#### Delphic

##### Strat-Talker
A Fender Jaguar and the Duo Sonic both already have a 24” scale length. But if you know how scale length and frets work then you’d know that they aren’t equally spaced. Once you determine what scale length you use a factor to divide into that length. Say your scale is 24” then you take 24 inches and divided it by 17.817 which gives you a number which is the distance to the first fret. Then you subtract that number and then take the remainder and divide it again by 17.817 which gives you the distance from the first fret to the second fret. You keep repeating this process until you have the number of frets you want on your guitar.
Damn. Now I know why the guitars that I build sound funny.

#### amstratnut

##### Peace thru Music.
Whats an 5/32 of a milimeter?

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#### Butcher of Strats

##### Most Honored Senior Member
Whats an 5/32 of a milimeter?
Lets see, tens are mm so take the 5 and double to ten sixteenths where 16 is twice the size of 32 which is like 16mm movie film which forgot to be tens and double that to 35mm movie film which darnint is not double but was originally 13/8" movie film and the next size up is 120 which does not measure 120 anything anywhere and is really 2 1/4" film which we agree has frame sizes of 6x6cm, 6x7cm, 6x9cm and even 6x4.5cm all on 2 1/4" film, then next up we have 4x5" and 8x10" sheet film which nobody can figure out metric dimensions of and further the standard lens for 8x10" film is 300mm which started out as a 12" lens but then due to humanity being confused got renamed 300mm which is incorrect because: humanity and actually 305mm but who's counting!

Was there a question?

#### Butcher of Strats

##### Most Honored Senior Member
Wait I think I have the rosetta stone that connects the frisky mm to the sleeping dog inch.
I built this partscamera from vintage Japanese German and American parts plus some new American machinist made parts who probably uses the metric system with his CNC run USA mills.
The film back system I chose is from the Mamiya Press camera favored by photojournalists some time last Century. Nice because backs come in 6x7 or 6x9. More frames from the smaller format.
The lens is a German Schneider on a German Linhof board in a German Compur shutter mounted to a piece of American road sign stolen by a butcher.
Those shutters have American made equivalents or are they Japanese? Anyhow, the Compur has less of a clack and more of a small bird sneeze tone. Plus the iris has twice as many blades or maybe 3x as many so the circles of CONFUSION are not HEXAGONS.
Purpose built for close in work in crowds of people without looking through the camera. The pic in the frame there was shot with an old German Leica, 35mm lens and 35mm film but focused to 7' as in seven feet which are not the least bit metric but are handy when not looking throuhnthe camera because my feet can measure distances.

So, the partscamera is fixed focus which saves two pounds weight and 400 pounds sterling. Helicals are spendy.
Now here is the rosetta stone part.
Which the fixed focus set (to 7 feet) by using ground glass, a loupe, and shims (one shim being birch from the Baltics) after getting the rough focus, the 6x7cm back equates to a 6x7 foot frame area!
That with the 65mm lens I chose for the close quarters application.
And if I switch to the 6x9cm back the field of view is 6x9 feet!

So while I do not suggest rose colored glasses, I do posit that we need to play guitar more often.

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#### dirocyn

##### Most Honored Senior Member
Gold Supporting Member
It's always half the length of the root you measure from. If you're measuring an open string and the scale length is 248mm, the octave is 124mm. But if you are measuring from the 12th fret, the octave is 62mm. And if you are measuring from the 24th fret, the octave is 31mm.

It also works out the same way, if you know the wavelength of the sound in air--the octave will be half the wavelength. So if the speed of sound is 343 m/s, 10000Hz has a wavelength of 0.0343. Or 34.3mm. The octave of that would be 20,000hz, supposedly the highest pitch humans can hear. And the wavelength is 17.15mm.

Octaves still exist above that, but that's music for porpoises, not for humans.

#### Butcher of Strats

##### Most Honored Senior Member
It's always half the length of the root you measure from. If you're measuring an open string and the scale length is 248mm, the octave is 124mm. But if you are measuring from the 12th fret, the octave is 62mm. And if you are measuring from the 24th fret, the octave is 31mm.

It also works out the same way, if you know the wavelength of the sound in air--the octave will be half the wavelength. So if the speed of sound is 343 m/s, 10000Hz has a wavelength of 0.0343. Or 34.3mm. The octave of that would be 20,000hz, supposedly the highest pitch humans can hear. And the wavelength is 17.15mm.

Octaves still exist above that, but that's music for porpoises, not for humans.
If I told you I am a porpoise, would you still...

#### 4pickupguy

##### Strat-Talker
I hate fractions, therefore I love the Metric system.
150 3/7ths mm….

#### Butcher of Strats

##### Most Honored Senior Member
Funny on the subject of language stuff, I just got banned at the TDPRI for "language" but I know I did not post any swear words or even abbreviations of swear words.
No clue what the language misuse was.

Maybe I used the wrong numerical language???

#### Caffiend

##### Strat-Talker
If this was a serious question, no - they're as bad as each other and it's mostly what you're used to. In Europe and parts of the UK aged under 50 or so, we find the fractions involved in using inches for anything serious to be a pain and find the plain speaking numbers of the metric system much easier to deal with for details. If we were talking about a 24" scale then obviously this divides nicely by 12. For 25.5 though I really don't see an advantage.

#### Scott Baxendale

##### Most Honored Senior Member
Silver Member
If this was a serious question, no - they're as bad as each other and it's mostly what you're used to. In Europe and parts of the UK aged under 50 or so, we find the fractions involved in using inches for anything serious to be a pain and find the plain speaking numbers of the metric system much easier to deal with for details. If we were talking about a 24" scale then obviously this divides nicely by 12. For 25.5 though I really don't see an advantage.
What makes you think that you need to use fractions with the imperial system? My caliper is in inches, but each inch is divided by tenths, hundredths, and thousandths. This makes the math work exactly the same as in the metric system. I use an engineers rule with inches divided by tenths.

1/8”=.125”, 1/4”= .250”, 1/2“=500” etc.

Fractions aren’t that hard either.