MET 349 � Stringed Instrument Design and Manufacture



Mark French

138 Knoy Hall






Technology of the Guitar


ISBN 978-1-4614-1920-4





This class meets for lecture twice each week and for lab four times each week.Initially, labs will be divided between CAD work and fabrication in the guitar lab.


The central task for the semester is designing and building solid body electric guitars.You will work in teams of 5-7 people and each team will design its own instrument.Each team must complete one instrument for each team member.You will each have a body blank to start with.


The teams will have a parts and materials budget of $200 per instrument.I do have a few parts in the guitar lab.If any of them can be used for your guitars and I can do it fairly, I�ll donate them.


There are three allowable suppliers:All Parts, Stewart MacDonald and Guitar Fetish (no, I don�t know who names these companies).The difference between the lab fee and your budget is used for consumable materials like glue, bits, blades and replacement parts.If there is money left over at the end of the semester, we can order gig bags.


No parts orders will be placed until all teams have 2D layouts completed and approved.There will be one parts order from each supplier.Successful manufacturers plan their operations carefully; if additional orders are required because of poor planning, students will have to order the parts themselves.Additional orders required for reasons beyond the control of the build teams will not be penalized � you pay for your mistakes, not mine J.


Lecture Schedule




Lecture Topic



Homework Due Date



Intro to class

Selection of build groups

History of the guitars

Ch 1



Intro, notes and scales

Ch 2.1




Scales and Chords

Ch 2.2



Impedance Matching




Fret Layout

HW #1:


1 - Find the notes that make up:

         C major scale

         D major scale

         A minor scale

2 � Find the notes that make up:

         C major chord

         D major chord

         A minor chord

         F major chord

         G major chord

         E minor chord

3 - Find the notes for a major scale starting at A2 and the corresponding frequencies.Calculate these values � don�t just copy them from the book.

4 - Repeat for a major scale starting at C2

5 � Complete Instrument Budget for Each Group.Each group member should attach a copy to the HW set.


Due Date: 7/6/15


Aesthetic Elements of Instrument Design

HW #2:


Calculate the fret layout for the following scale lengths:

1.    25.5 inch guitar

2.    24.75 inch guitar

3.    34 inch bass

4.    600mm classical guitar

5.    13.7 inch mandolin

6.    28 inch baritone guitar

Due: 7/8/15



Sound Pressure Level,

String Tension

Ch 2.3 � 2.6

HW #3:

1 � If a sound has an RMS pressure of 0.50 Pa, what is the sound pressure level in dB?

2 � If a sound has an SPL of 110 db (really loud), what is the RMS pressure?

3 � If a sound has an SPL of 94 dB, what is the RMS pressure?

4 � Go on the interwebs and find the standard SPL for microphone calibrators.What RMS pressure does this correspond to?Note, some calibrators have more than one setting.Pick the most common setting.

5 � If a steel string with a diameter of 0.012 inch is tuned to 330 Hz, what is the tension?Assume E=205 GPa and a density of 7850 kg/m^3. Scale length is 647.7mm.Report the answer in both Newtons and pounds.

6 � What if the string has a diameter of 0.008 inch?

7 � A plain steel string has a diameter of 0.011 inch and a length of 711.2 mm (28 in).If it is tuned to 330 Hz, what is the required tension?


Due: 7/22


Real strings and inharmonicity




No Lecture




No Lecture





Sound Pressure Levels and String Tension




Real Strings

Note: The frequencies for the open strings on a guitar at standard tuning are:


E - 84.2 Hz

A - 110

D - 146.8

G - 196

B - 246.9

E - 329.6

HW #4:

1 � A steel G string has a diameter of 0.43mm.If the scale length is 647.7mm, find the predicted frequency for the open string and the string being played at the 12th fret.Assume E=205 GPa and a density of 7850 kg/m3.Use tension predicted by ideal string equation

2 � What changes in length would be needed for the frequencies to be correct at the 12th fret and the 18th fret?

3 � A Nylon G string has a diameter of 1.023mm and E=1.95GPa.Find the tension assuming it is an ideal string and density is 1100 kg/m3

4 � Find real string frequency for the open string and the string being played at the 12th fret

5 � For the real G string in problem 1, how far would the saddle need to move for the string to be at correct pitch at the 12th fret?What would be the resulting tension?

Due 7/29




Resistance and impedance

Input and Output Impedance

HW #5:

1 � For a voltage divider where R1 is the output resistance of a pickup and R2 is the input resistance of an amplifier.If Vin=12V, find Vout for these values:

a)    R1=1MΩ, R2=100kΩ

b)    R1=1MΩ,


c)    R1=100kΩ, R2=1MΩ

d)    R1=15kΩ, R2=500kΩ




Review for Exam






Open Book, Open Notes





















Practice Problem


Use the real string equation for all 4 problems


1 � Calculate the frequency error for a 25.5 inch nylon G string (E=10^6 psi) with a diameter of 0.040 in, stopped at the 12th fret.String Tension is 11.7 lb.Calculate the error due to inharmonicity.Assume that nylon is 1250 kg/m3.

2 � Calculate frequency error for a steel G string (E=29*10^6 psi).String diameter is 0.023 in.String Tension is 27.2 lb.Assume steel is 7850 kg/m3.

3 � Calculate the saddle offset needed for the nylon string using frequency at the 12th fret

4 � Calculate the saddle offset needed for the steel string.


Note:Use the metric system for all calculations.If you need help converting units, so to








Practice Questions:


1 � How far from the nut would the 12th fret be on a guitar with a 24 in scale length?


2 � If a string is 700mm, is made from steel and has a diameter of 0.4mm, what tension is required for it to be at a frequency of 150 Hz?


3 � What are the notes in an F major scale?


4 � What are the notes in an A# chord?


5 � The bias resistors, RA and RB, in a pre-amp need to create a bias voltage of 4.5V and the circuit is powered by a 9V battery.The sum of the two resistances must be 440kΩ.Find RA and RB


















Exam:������������� 20%

Homework:���� 15%

Guitar: ���������� ��55%

Design:����������� completeness, accuracy, creative solutions to design problems, aesthetics

Construction:accuracy, organization, meeting build schedule, build process, jigs and fixtures

Final Product: accuracy, playability, finish, balance, sound, aesthetics

Peer Grade���� 10%We added this after a class discussion in which we decided that peer ratings would capture important information that might be missed by the other grades