SG: Define "in tune" as you would use it.
Compensating Bridge
Moderator: Shoshanah Marohn
To expound on what Ed Packard and Donny Hinson aid; both Bill Stafford and I were well aware that harmonics are attained over a rather wide area at a given fret.
However, the loudest and clearest harmonic is ONLY obtained at one single point. IE, if one starts far enough to the left of a harmonics' fret and progressively moves further and further to the right, the enfamous "bell curve" will be experienced.
In other words, it will go from NO harmonics at all; a barely percetable harmonic to a peak where it is loudest and clearest; doing the reverse; to no harmonic at all on the right side of the fret.
Both Bill and I y maticulously kept this in mind as were running the test. It took some time and in NO case was there ANY discernable fall off in the peak harmonic at a given location when an appropriate pedal was engaged and disengaged.
I am sure there was. In fact I KNOW there was. However to his ears, and later mine on my guitar, I simply cannot hear any difference.
The summation as far as I am concerned is that while it would be assumed by most (INCLUDING me) that a changer that moved laterally rather than pivoting on an axle, would cause audible intonations all over the place (as pedals and knee levers were engaged) it simply did not and does not happen, (to our ears at least).
I must say that NO body I have EVER heard plays MORE in tune to my ears than Tom Brumley. And surely IF there was intonation problems, HE would be the first to hear it. So would Bill Stafford. And I feel certain the same would happen to countless others.
Again, such has not been the case. Because the changer is such an inovative and unique idea, I am delighted it turned out this way. If it had not, it would be another case of a "good Idea" gone down the drain,
carl
However, the loudest and clearest harmonic is ONLY obtained at one single point. IE, if one starts far enough to the left of a harmonics' fret and progressively moves further and further to the right, the enfamous "bell curve" will be experienced.
In other words, it will go from NO harmonics at all; a barely percetable harmonic to a peak where it is loudest and clearest; doing the reverse; to no harmonic at all on the right side of the fret.
Both Bill and I y maticulously kept this in mind as were running the test. It took some time and in NO case was there ANY discernable fall off in the peak harmonic at a given location when an appropriate pedal was engaged and disengaged.
I am sure there was. In fact I KNOW there was. However to his ears, and later mine on my guitar, I simply cannot hear any difference.
The summation as far as I am concerned is that while it would be assumed by most (INCLUDING me) that a changer that moved laterally rather than pivoting on an axle, would cause audible intonations all over the place (as pedals and knee levers were engaged) it simply did not and does not happen, (to our ears at least).
I must say that NO body I have EVER heard plays MORE in tune to my ears than Tom Brumley. And surely IF there was intonation problems, HE would be the first to hear it. So would Bill Stafford. And I feel certain the same would happen to countless others.
Again, such has not been the case. Because the changer is such an inovative and unique idea, I am delighted it turned out this way. If it had not, it would be another case of a "good Idea" gone down the drain,
carl
-
Donny Hinson
- Posts: 21192
- Joined: 16 Feb 1999 1:01 am
- Location: Glen Burnie, Md. U.S.A.
-
ed packard
- Posts: 2162
- Joined: 4 Aug 1998 11:00 pm
- Location: Show Low AZ
I would question that the 3/16" motion measurement is the increase in string length, because as I recall the changer is neither totally circular rotary or straight linear, but a hybrid, hence the point where the string departs from the finger would not vary by 3/16" for a 3/16" motion of a point on the finger.
Using my thumbnail and vernier calipers, I get an acceptable 1/2 string length harmonics location resolvable to about a .050" span.
The top of the "bell curve" is not a point, but an area with essentially a flat with dimensions that are a function of the system Q (reactance to resistance ratio). This bell curve is not the one familiar to the quality assurance folk.
There is a limit to the difference in amplitude that we can hear, and the difference in location that we can perceive with the unaided eye; They become less accurate when removed in time from a reference.
The above points do not invalidate the conclusions reached from the experiments, they do however bring into question some of the dimensional/motion/location details related to the experiments. The equations for string frequencies and harmonics as a function of length, diameter, tension, material, etc. are available in just about any physics book; The effect of clamping method is a bit more obscure.
It is reasonable to expect that an increase in the length of a string would provide a change in the locations of a strings harmonic nodes and loops, but by how much? Enter the equations, ..if there is a difference between the described results and the equations, check the "givens".
For anyone that cares:
Carl and Bills scale length is given as 25.5"; Therefore the half string length falls at 12.75".
If the string were to be extended by the amount measured as 3/16" = 0.1875", the new string length would be 25.6875", and the new half string length would be 12.84375"(carried to the extreme).
The difference in the half string points for the original and the new would be 0.09375".
The question becomes, can one reasonably resolve the physical location of these half string position differences by a portion of 0.09375" using their finger ala common chiming methods, ..if yes then either the equations for string vibration are wrong or the 3/16" dim is not the change in string length.
I am glad that these things come up to break up the monotany of life in the White mountains of AZ!
Using my thumbnail and vernier calipers, I get an acceptable 1/2 string length harmonics location resolvable to about a .050" span.
The top of the "bell curve" is not a point, but an area with essentially a flat with dimensions that are a function of the system Q (reactance to resistance ratio). This bell curve is not the one familiar to the quality assurance folk.
There is a limit to the difference in amplitude that we can hear, and the difference in location that we can perceive with the unaided eye; They become less accurate when removed in time from a reference.
The above points do not invalidate the conclusions reached from the experiments, they do however bring into question some of the dimensional/motion/location details related to the experiments. The equations for string frequencies and harmonics as a function of length, diameter, tension, material, etc. are available in just about any physics book; The effect of clamping method is a bit more obscure.
It is reasonable to expect that an increase in the length of a string would provide a change in the locations of a strings harmonic nodes and loops, but by how much? Enter the equations, ..if there is a difference between the described results and the equations, check the "givens".
For anyone that cares:
Carl and Bills scale length is given as 25.5"; Therefore the half string length falls at 12.75".
If the string were to be extended by the amount measured as 3/16" = 0.1875", the new string length would be 25.6875", and the new half string length would be 12.84375"(carried to the extreme).
The difference in the half string points for the original and the new would be 0.09375".
The question becomes, can one reasonably resolve the physical location of these half string position differences by a portion of 0.09375" using their finger ala common chiming methods, ..if yes then either the equations for string vibration are wrong or the 3/16" dim is not the change in string length.
I am glad that these things come up to break up the monotany of life in the White mountains of AZ!