Results 1 to 25 of 25

Thread: Don't Understand "scale length"

  1. #1
    Registered User
    Join Date
    Dec 2004
    Location
    Albuquerque, New Mexico
    Posts
    422

    Default Don't Understand "scale length"

    I get that different instruments have different scale lengths. What confuses me is where the measurement comes from? My Trinity College mandola has a scale length of 17 (inches, centimeters?) and I know there are stretches that I don't remember from the H1 Gibson I had. But doesn't each fret have to be the same width to keep the instrument in tune? In other words, isn't the distance from one fret to the next a constant to get an in-tune scale? How does this work?
    Daniel Kaufman

  2. #2
    Hester Mandolins Gail Hester's Avatar
    Join Date
    Feb 2004
    Location
    Poulsbo, WA (Seattle)
    Posts
    1,998

    Default Re: Don't Understand "scale length"

    Simply put, the scale length is the distance from the leading edge of the nut to the leading edge of the bridge, the active string length.

    Fret positions are typically calculated using equal temperament, successively dividing the scale length minus the offset to the previous fret by 17.817. This series of calculations puts the 12th fret (octave) at exactly half the scale length.
    Gail Hester

  3. #3
    Mando-Accumulator Jim Garber's Avatar
    Join Date
    Mar 2003
    Location
    Westchester, NY
    Posts
    23,548

    Default Re: Don't Understand "scale length"

    Yes there are mathematical ratios to determine the fret distance. As far as scale goes the easiest way to determine that for us math-challenged is to measure from the nut to the 12th fret and double it. the 12th fret is the middle of the scale length.

    Your mandola is probably 17 inches not centimeters. Std Gibson mandolin scale length is 13 7/8 inches and classical (bowlback) scale is 13 inches.
    Jim

    My Stream on Soundcloud
    Facebook

    Playing lately:
    1923 Gibson A2 black snakehead -- Brentrup A4C -- 1915 Frank Merwin Ashley violin -- Huss & Dalton DS -- 1937 Gibson L-Century -- 1939 Gibson L-00 -- ca. 1890s Fairbanks Senator Banjo -- ca. 1923 Vega Style M tenor banjo -- Gibson TB-Junior

  4. #4
    coprolite mandroid's Avatar
    Join Date
    Oct 2002
    Location
    Outer Spiral Arm, of Galaxy, NW Oregon.
    Posts
    14,845

    Default Re: Don't Understand "scale length"

    Length of the vibrating string .. I have an H 5 style mandola it's a 40cm scale 0.4M.
    .. on one string course, the intonation offsets in the bridge are variants from that ..
    writing about music
    is like dancing,
    about architecture

  5. #5
    Registered User
    Join Date
    Dec 2004
    Location
    Albuquerque, New Mexico
    Posts
    422

    Default Re: Don't Understand "scale length"

    If someone just explained this and I missed it, I apologize. So where on the instrument do the differences in scale length come from? Where on the instrument is the "extra" length on a 17in vs a 16in?
    Daniel Kaufman

  6. #6
    Moderator JEStanek's Avatar
    Join Date
    Oct 2004
    Location
    Pottstown, Pennsylvania, United States
    Posts
    13,418
    Blog Entries
    2

    Default Re: Don't Understand "scale length"

    There is no extra length. The scale length is a function of lenght, string gauge and tension. If a mandola comes in two scale lengths 16 or 17 inches and it is tuned the same (CGDA) there will be greater string tension on the 17 inch one than the 16 inch one (I hope I have that right and not backwards- I'm a microbiologist!). You'll sometimes hear about people saying shorter scale length octave mandolins sounding rubbery on the G courses (like a losse rubber band). This is a string tension function. You can get around that by using different string gauges. That's why the standard mandolin scale makes it easier to compare instrument to instrument more than when comparing mandolas, OMs, Zouks, or mandocellos.

    Jamie
    There are two things to aim at in life: first, to get what you want; and, after that, to enjoy it. Only the wisest of mankind achieve the second. Logan Pearsall Smith, 1865 - 1946

    + Give Blood, Save a Life +

  7. #7
    Registered User man dough nollij's Avatar
    Join Date
    Apr 2008
    Location
    The Real World
    Posts
    2,801

    Default Re: Don't Understand "scale length"

    I got confused about this when somebody converted a guitar to a mandocello. Since it will now use different gauge strings, have different tensions, and way different string tunings, it seemed that the guitar frets would be in the wrong places for a 'cello.

    I got to thinking about it, and figured out that the fret spacing will be the same, no matter the tuning. It is a math thing. If I put a C string on, the middle of the string will be at the 12th fret, and that'll be a C, an octave higher. The rest of the frets will be B,A,G,F, etc on up (towards the nut) the neck (with the appropriate extra frets for half steps).

    It was pointed out recently in another thread that the 12th fret isn't exactly 1/2 way-- it is tweaked a tiny bit to account for the deflection of the string and the string stretching.

    Pretty cool stuff!

  8. The following members say thank you to man dough nollij for this post:

    dmcol 

  9. #8
    coprolite mandroid's Avatar
    Join Date
    Oct 2002
    Location
    Outer Spiral Arm, of Galaxy, NW Oregon.
    Posts
    14,845

    Default Re: Don't Understand "scale length"

    A vibrating string's length , think of the nut as birth, the bridge as death,
    the length between those is when you make music,
    writing about music
    is like dancing,
    about architecture

  10. #9
    Registered User Woody Turner's Avatar
    Join Date
    Aug 2007
    Location
    Washington, DC, area
    Posts
    389

    Default Re: Don't Understand "scale length"

    "The scale length is a function of lenght, string gauge and tension."
    I respectfully disagree with this statement. The scale length is strictly a measure of distance between the nut and bridge; it is totally independent of string tension. Different string gauges affect tone, feel, and playability, but they don't affect scale length. I think the OP is asking about where the difference is added when a builder chooses to make an instrument with a 17" scale rather than a 16" one. Well, she could simply enlongate the neck only and make the diminishing spaces between the frets slightly wider on the longer instrument. Or she could also lengthen the body a tad, but with a longer fingerboard. Or both.
    David
    Clocks make no alliances.

  11. #10
    Mando accumulator allenhopkins's Avatar
    Join Date
    Mar 2006
    Location
    Rochester NY 14610
    Posts
    14,116

    Default Re: Don't Understand "scale length"

    Quote Originally Posted by JEStanek View Post
    The scale length is a function of length, string gauge and tension.
    I think what Jamie meant is that the pitch of the string -- the note that results when plucked -- is a function of length, string gauge and tension.

    The scale length is the scale length, period. You can measure it with a ruler. On mandolins and other "floating" bridge instruments, it's (slightly) variable, depending on where the bridge is placed. However, once the neck is fretted, there's only one place the bridge can be, and still have correct intonation up the scale.

    To raise a longer string to the same pitch as a shorter string of the same gauge (thickness), the tension must be greater. Therefore, instruments with longer scale lengths require either thinner or tenser strings to reach the same pitch as instruments with shorter scale lengths.

    The "floppiness" of lower strings on short-scale instruments, can be cured by using thicker strings, which have to be given more tension to reach the same pitch. However, since the stress on the top of the instrument is also a function of string length, thickness (gauge), and tension, one needs to consult a chart that indicates how much total force is exerted by strings of a particular length, thickness and tension. Too much, and the top can collapse, the neck bow upward, the tailpiece pull off, or other disasters.

    By the way, did I mention that the composition of the string -- what it's made from -- also affects the pitch, as well as length, thickness and tension? Many many factors come into play.
    Allen Hopkins
    Gibsn: '54 F5 3pt F2 A-N Custm K1 m'cello
    Natl Triolian Dobro mando
    Victoria b-back Merrill alumnm b-back
    H-O mandolinetto
    Stradolin Vega banjolin
    Sobell'dola Washburn b-back'dola
    Eastmn: 615'dola 805 m'cello
    Flatiron 3K OM

  12. #11

    Default Re: Don't Understand "scale length"

    Quote Originally Posted by FrDNicholas View Post
    ... But doesn't each fret have to be the same width to keep the instrument in tune? In other words, isn't the distance from one fret to the next a constant to get an in-tune scale? How does this work?
    No. On an instrument with a longer scale length the space between frets is longer than on a shorter scale length instrument.
    Example:
    On a 17" scale length (no matter the tuning) the distance from the nut to fret 1 is 61/64 of an inch.
    On a 16" scale length it is 57/64.
    On a 13 7/8" scale length it is 25/32 (or 50/64) of an inch.

    FWIW I used a handy little program by Jon Whitney named WFRET to come up with my numbers.
    Bill Snyder

  13. #12
    Moderator JEStanek's Avatar
    Join Date
    Oct 2004
    Location
    Pottstown, Pennsylvania, United States
    Posts
    13,418
    Blog Entries
    2

    Default Re: Don't Understand "scale length"

    Thanks, Allan. I wasn't clear and defined my term with it (length). No offense taken, David. I'm happy to have vague things I say get clarified! I hope the discussion is proving useful to the OP. I'm learning new stuff too.

    Jamie
    There are two things to aim at in life: first, to get what you want; and, after that, to enjoy it. Only the wisest of mankind achieve the second. Logan Pearsall Smith, 1865 - 1946

    + Give Blood, Save a Life +

  14. #13
    Needs Improvement Tobin's Avatar
    Join Date
    Mar 2009
    Location
    Kerrville, TX
    Posts
    3,570

    Default Re: Don't Understand "scale length"

    Since we're on the subject, and forgive me if this has been answered before, why is it that the bridge has a "zigzag" shape to it? The G and A strings are offset lengthwise from the D and E strings. Is this necessary for proper intonation, and if so, why? It seems that the offsets would change the scale length of these strings as opposed to the others. And no matter where or how you place the bridge, they will always be slightly different. A guitar bridge is pretty much straight across, although sometimes it has a notch for one string (the B string, as I recall). And most other instruments I've casually looked at have a straight bridge too. Why is the mandolin's offset like this?

    And is there such thing as a floating bridge with individual adjustments for each pair of strings? Kind of like the way electric guitars usually have individual adjustments for length?

  15. #14

    Default Re: Don't Understand "scale length"

    The"zigzag" pattern is the compensation. Due to the different gauges of the strings they all require differing compensation. As far as guitars most of the steel string guitars have the saddle set at a slight angle such as in this photo.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Guitar_bridge.jpg 
Views:	153 
Size:	27.6 KB 
ID:	40579  
    Bill Snyder

  16. #15
    Musical Photo Junkie Chris Keth's Avatar
    Join Date
    Mar 2009
    Location
    Glendale, CA
    Posts
    614

    Default Re: Don't Understand "scale length"

    Most stringed instruments have some sort of compensated bridge saddle to be able to intonate. Some guitars just have the saddle slanted and it's pretty good but not exact. Electric guitars have bridges with separate saddles for each string that can be individually adjusted.

    The very simplified jist of it is that you're trying to make each effective string length the same as the scale length of the instrument. The problem with just making each string that length is that the lower, fatter strings have a stiffness to them and they can't vibrate right up to the saddle like a thin string can. To conquer that, we make the fatter strings a bit longer. If we could make each string the same diameter somehow (like if we had a ductile metal dense enough to make a .10 high E for a guitar weight the same as a .056 string), the saddle could be straight across and good intonation would still be possible.


    Eric Clapton's old 12-string martin (or guild, I forget) came up on ebay not long ago and it has a very elaborate compensated saddle. I saw a better photo than this one and each string in each course has it's own compensation via different filed bevels of the bone.


  17. #16
    Needs Improvement Tobin's Avatar
    Join Date
    Mar 2009
    Location
    Kerrville, TX
    Posts
    3,570

    Default Re: Don't Understand "scale length"

    The"zigzag" pattern is the compensation. Due to the different gauges of the strings they all require differing compensation. As far as guitars most of the steel string guitars have the saddle set at a slight angle such as in this photo.
    Yes, I understand why guitar bridges are set at an angle. That's not unlike how mandolin bridges can be set at an angle. But that doesn't explain the zig-zag of the bridge. What's the logic behind the compensation being alternated like that?

    The problem with just making each string that length is that the lower, fatter strings have a stiffness to them and they can't vibrate right up to the saddle like a thin string can. To conquer that, we make the fatter strings a bit longer.
    That would make sense to me if the mandolin bridge design were compensated so that the fatter G and D strings were longer than the thinner A and E strings. But the way the bridge is compensated, the G and A strings are longer than the D and E strings. It still doesn't make any sense to me why this is so.

    It would seem to me that since mandolin strings are tuned at 7ths from each other (a linear progression across the strings), the bridge should also have a linear progression in scale length for proper intonation. If one sets the bridge so that the G and E strings are properly intonated, without a linear bridge between them, shouldn't the D and A strings be off a bit?

    I know, I'm probably overthinking this. The design obviously works as is. But I'm an engineer; I can't help it. It has to not only work, but make sense to me.

  18. #17
    Capt. E Capt. E's Avatar
    Join Date
    May 2008
    Location
    Austin, Texas
    Posts
    2,683

    Default Re: Don't Understand "scale length"

    I just realized that many string sets vary in gauge and that may have an affect on intonation. Example: the gauges of D'Addario J-74's are from E to G are 11,15,26,40. The gauges of Gibson Sam Bush strings are 11, 14, 25, 41. Do these differences have a "significant" affect on intonation?
    Jammin' south of the river
    '08 Weber Bighorn
    '20 Gibson A-2
    Button Accordion
    Harmonica
    Penny Whistle
    My albums: http://www.mandolincafe.com/forum/album.php?u=7616

  19. #18
    Needs Improvement Tobin's Avatar
    Join Date
    Mar 2009
    Location
    Kerrville, TX
    Posts
    3,570

    Default Re: Don't Understand "scale length"

    They will require adjustments to the intonation, yes, mostly as a result of different tensions required for different gauge strings. The height of the action will play a large part too.

  20. #19
    Mando accumulator allenhopkins's Avatar
    Join Date
    Mar 2006
    Location
    Rochester NY 14610
    Posts
    14,116

    Default Re: Don't Understand "scale length"

    OK, I'm starting to get a bit confused. Is there a consensus that bridge placement would need to be changed, if one used a different gauge or composition of strings? That hasn't been my experience, except in one fairly extreme case, when I went from steel to nylon strings on a banjo-ukulele.

    It is true that the action of pressing a string down on the neck, stretches it slightly, which would "sharp" it. Strings of different gauges show this effect to different degrees, so a "straight across" bridge generally doesn't work; the thinner strings and the thicker strings "sharp" at different rates, and a bridge needs to be slanted, or compensated, to allow for the difference.

    But I've never heard that changing from light to medium strings requires a different scale length. If that's true, I've been missing something all these years. Hope to be enlightened...
    Allen Hopkins
    Gibsn: '54 F5 3pt F2 A-N Custm K1 m'cello
    Natl Triolian Dobro mando
    Victoria b-back Merrill alumnm b-back
    H-O mandolinetto
    Stradolin Vega banjolin
    Sobell'dola Washburn b-back'dola
    Eastmn: 615'dola 805 m'cello
    Flatiron 3K OM

  21. #20
    Needs Improvement Tobin's Avatar
    Join Date
    Mar 2009
    Location
    Kerrville, TX
    Posts
    3,570

    Default Re: Don't Understand "scale length"

    But I've never heard that changing from light to medium strings requires a different scale length. If that's true, I've been missing something all these years. Hope to be enlightened...
    Considering that intonation is initially set on any given pair of strings by checking the open tone with a fretted tone (at the 12th fret), then it is obvious that the change in tension when fretted comes into play. And it's true that different gauge strings which require different tensions for open tone will have different changes in tension when pushed down the same distance to the fret. So that minor differential in tension between the two sets of strings will require minor adjustment to scale length. Only because of the change in tension when fretted. And like I said above, the height of the action will come into play here as well. The lower the action, the less additional tension that is added when fretted, and thus the less differential in scale length between two different gauge strings.

    I hope that explanation of my logic made sense.

  22. #21
    Musical Photo Junkie Chris Keth's Avatar
    Join Date
    Mar 2009
    Location
    Glendale, CA
    Posts
    614

    Default Re: Don't Understand "scale length"

    Tobin, the reason for the zigzag is that wound and unwound strings need to be compensated for differently. I can't explain the exact reason but I suspect it's a combination of sting mass, tension, and stiffness of the metal. So you'll have the stairstep pattern for the unwound strings and a similar but slightly further from the nut stairstep for the wound strings. It's easier to see on an electric guitar bridge:




    As for having to set intonation if you change string gauge, I think that depends on what you play and how sensitive your ears are. For electric guitar, I set my intonation with a strobe tuner because I want it to be as "on" as possible everywhere on the neck because I play a lot of music with long sustained notes as well as play with other instruments. For the mandolin, I really doubt it's quite as sensitive because of the sustain issue. If your note is a tiny, tiny bit off, nobody will notice because it's never sustained long enough for your head to think about it. It's sort of like suggesting a higher note by bending only partway up to it. If you held the note you bend to for any amount of time it would sour but it sounds fine because you don't hold it and go to a solid fretted note next in the phrase and your mind fills in the gap.

  23. #22
    Needs Improvement Tobin's Avatar
    Join Date
    Mar 2009
    Location
    Kerrville, TX
    Posts
    3,570

    Default Re: Don't Understand "scale length"

    So you'll have the stairstep pattern for the unwound strings and a similar but slightly further from the nut stairstep for the wound strings.
    Now THAT makes sense to me. Thank you very much. I hadn't thought of it like that.

  24. #23
    Musical Photo Junkie Chris Keth's Avatar
    Join Date
    Mar 2009
    Location
    Glendale, CA
    Posts
    614

    Default Re: Don't Understand "scale length"

    Glad I could help. I'm very new to mandolin (don't even have a playable one, yet) but not to some other stringed instruments.

    I should mention one other thing that makes me think that tension is a big part of intonation. If the G string (on the guitar whose bridge I posted) were wound, the saddle would be up closer to the nut than the D string's. Something about the thinner core wire being lower tension but, with windings, being a similar mass to the unwound string.

  25. #24
    Confused... or?
    Join Date
    Dec 2008
    Location
    Over the Hudson & thru the woods from NYC
    Posts
    1,902

    Default Re: Don't Understand "scale length"

    FWIW, I've seen at least one "mandolin" bridge on e-Bay that was actually a mandola bridge. Mandolas lose the mando's high E strings but add a low C course (I think?), so three courses are wound and only one is unwound. This moves the bridge's "zig" from the middle to in between the 1st and 2nd sets of strings.

    Thus, the mandola's different offset is STILL between the wound Ds and plain As, just as on mandolin. (Insert "Twilight Zone" music here!)
    Last edited by EdHanrahan; Apr-02-2009 at 10:50am. Reason: clarity
    - Ed

    "What our group lacks in musicianship is offset by our willingness to humiliate ourselves." - David Hochman

  26. #25
    Mandolin tragic Graham McDonald's Avatar
    Join Date
    Oct 2004
    Location
    Canberra, Australia
    Posts
    1,224

    Default Re: Don't Understand "scale length"

    The reason you get a 'zig-zag' bridge saddle on a mandolin is that the amount of 'compensation' - the little extra on the scale length to make it play in tune - is dependent on the gauge of the plain string or in the case of the wound strings the gauge of the core wire. The core of a D string is much the same as the a plain E, so about the same compensation.

    Of course getting the harmonic and the fretted note at the 12th fret the same by moving the bridge back and forwards is only part of playing in tune. Frets are placed in an average "well-tempered" positioning based on the 17.817 formula, and that means that some notes in some keys are always going to be a little out of tune. Some players of fretted instruments get very upset when they realize they can never play in tune. Other just deal with it and play music instead

    cheers

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •