Prepared by: Simon Edwards Page 1 of 4 Date: 20/05/2012 File: 140526 String Tension Paper Rev Initial Issue SRE STRING TENSION AND VINTAGE 1960’S RICKENBACKER 12 STRING ELECTRIC GUITARS 1. INTRODUCTION 1960’s Vintage Rickenbacker 300 Series twelve string guitars with “set neck” construction are, over time, known to experience changes in the neck to body angle. This can lead to valuable instruments becoming difficult or impossible to play as the bridge runs out of downward adjustment to compensate for the changing neck angle, and a very high string action becomes evident. The only way to rectify the problem at this point, is to have the guitars neck to body connection re-set. The problem is widely attributed to a combination of three factors, the design of the connection, construction methods and string tension. This study was only to address the final factor, string tension, as it is the only variable that can be controlled effectively without resorting to intrusive repair to the instrument. A second concern for owners of this type of guitar has been reported structural failures of the ‘R’ type string tail piece used on many models made since the 1980’s. The material composition used to cast this item has apparently changed a number of times over the decades. Guitars with original manufacturer supplied strings have been known to break the tailpiece, most probably due to string tension on instruments made from approximately the late 1980’s and through the 1990’ s. Instruments from the 1960’s and 70’s have a different casting pattern and material makeup that is more robust and typically have not been known to fail with any great regularity. 2. BACKGROUND – STRING TENSION For the majority of enthusiasts string tension is most commonly determined for musical instruments by using long standing and well understood physics formulas. This method is commonly described in high school physics text books and of course is readily found on the internet. Tension is commonly predicted by calculation rather than by measurement, by all but the string manufacturers themselves. Obviously calculation methods are considerably less expensive and the results are considered by many luthiers and enthusiasts to give acceptably accurate tension data. However on the fragile neck design of the early Rickenbacker twelve string guitars, string tension is critical and more accurate data would be valuable to owners of such instruments. Available tension data from various manufacturers may not all be obtained with the same methods and not all manufacturers publish their data. As such valid comparisons of measured tension between types and makers are difficult to make, particularly when methodologies are not published or understood. 3. STRING CONSTRUCTION A wound strings construction make up, techniques of assembly, tolerances, materials utilised and possibly the strings age can make for a complex set of variables. Each manufacturer varies these parameters from one another in some obvious and in some very subtle ways. These variables were studied by measurement and dissection for a number of the string sets to see how they were constructed. This information is presented in the first table.
A study and data set for 11 different sets of strings for rickenbacker electric 12 string guitars. Data is useful for any electric guitar.
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Prepared by: Simon Edwards Page 1 of 4 Date: 20/05/2012 File: 140526 String Tension Paper Rev Initial Issue SRE
STRING TENSION AND VINTAGE 1960’S RICKENBACKER 12
STRING ELECTRIC GUITARS
1. INTRODUCTION
1960’s Vintage Rickenbacker 300 Series twelve string guitars with “set neck” construction are, over
time, known to experience changes in the neck to body angle. This can lead to valuable instruments
becoming difficult or impossible to play as the bridge runs out of downward adjustment to
compensate for the changing neck angle, and a very high string action becomes evident. The only
way to rectify the problem at this point, is to have the guitars neck to body connection re-set. The
problem is widely attributed to a combination of three factors, the design of the connection,
construction methods and string tension. This study was only to address the final factor, string
tension, as it is the only variable that can be controlled effectively without resorting to intrusive repair
to the instrument.
A second concern for owners of this type of guitar has been reported structural failures of the ‘R’
type string tail piece used on many models made since the 1980’s. The material composition used
to cast this item has apparently changed a number of times over the decades. Guitars with original
manufacturer supplied strings have been known to break the tailpiece, most probably due to string
tension on instruments made from approximately the late 1980’s and through the 1990’s.
Instruments from the 1960’s and 70’s have a different casting pattern and material makeup that is
more robust and typically have not been known to fail with any great regularity.
2. BACKGROUND – STRING TENSION
For the majority of enthusiasts string tension is most commonly determined for musical instruments
by using long standing and well understood physics formulas. This method is commonly described
in high school physics text books and of course is readily found on the internet.
Tension is commonly predicted by calculation rather than by measurement, by all but the string
manufacturers themselves. Obviously calculation methods are considerably less expensive and the
results are considered by many luthiers and enthusiasts to give acceptably accurate tension data.
However on the fragile neck design of the early Rickenbacker twelve string guitars, string tension is
critical and more accurate data would be valuable to owners of such instruments.
Available tension data from various manufacturers may not all be obtained with the same methods
and not all manufacturers publish their data. As such valid comparisons of measured tension
between types and makers are difficult to make, particularly when methodologies are not published
or understood.
3. STRING CONSTRUCTION
A wound strings construction make up, techniques of assembly, tolerances, materials utilised and
possibly the strings age can make for a complex set of variables. Each manufacturer varies these
parameters from one another in some obvious and in some very subtle ways.
These variables were studied by measurement and dissection for a number of the string sets to see
how they were constructed. This information is presented in the first table.
Prepared by: Simon Edwards Page 2 of 4 Date: 20/05/2012 File: 140526 String Tension Paper Rev Initial Issue SRE
4. OBJECTIVE and COMENTARY ON STRING SETS TESTED
Debate surrounding the best type or maker of strings flourishes amongst enthusiasts even on the
single focus point of tension. The objective of this brief paper is to present the results of a
comprehensive set of measurements of string tension for a number of popularly used sets of strings
on Rickenbacker 12 string guitars. In addition to these modern string sets, one new old stock set of
Rickenbacker Redbox strings was also tested.
The sets tested were selected based upon what gauges were deemed to be widely available and
commonly used today by 1960’s period music enthusiasts. Sets and types that are commonly
debated on internet forums were targeted that fitted into this criteria.
Once preliminary testing had been completed two specially ordered sets of very light 0.009” gauge
strings were added to the testing, one from Thomastik Infeld (TI) and one from Pyramid. A set of
these very light strings (TI’s) was also sent to the owner of a 360/12c63 for playability testing.
As this undertaking was carried out entirely by a very small group of private enthusiasts, the number
of sets was limited on financial grounds. It is noted that other sets may be relatively commonly used
at present also. A total of eleven sets of strings were tested.
A key objective was to present the tension results to other enthusiasts in a completely impartial
manner.
5. METHODS and OBSERVATIONS
A testing rig was devised with importance placed around a robust design that would produce
consistently repeatable and accurate results.
Key Design Points of the Testing Rig:
a. The scale length of the string placed in tension was set at 628mm (24.75”), the scale length
used on the 300 series full scale Rickenbacker 12 string instruments.
b. A substantial hardwood chassis formed the basis of the test rig. In testing this proved to behave
consistently in deflection as it was clamped to a substantial steel engineering workshop bench.
It was essential that the chassis was tested for deflection only in that it would yield consistent
behaviour and hence results in repeated testing.
c. The key instrument used was a precision Shimpo digital force gauge that had been recently lab
calibrated and certified. The gauge had a simple clevis attachment designed for it in an
arrangement that allowed a string to be wound around it three times. This set one end of the
string.
d. The string then extended along the scale length and passed over a vintage Rickenbacker 360
type guitar bridge, and then extended at a break angle the same as a 1966 360/12, down to a
Gotoh guitar tuner, thus allowing the string to be brought up to tension for any desired
frequency.
e. A chromatic digital Korg tuner was used for setting frequencies. Each string was stretched and
retuned several times to 441Hz concert pitch, as per standard guitar stringing practice.
Prepared by: Simon Edwards Page 3 of 4 Date: 20/05/2012 File: 140526 String Tension Paper Rev Initial Issue SRE
Method:
a. Strings were installed on the test rig and tested individually, not complete sets of twelve strings
at a time.
b. The ball end of the strings was excluded from the effective scale length placed into tension for
testing.
c. The method utilised for testing was focused upon obtaining the best possible tension data that
would relate to strings as they would be used on a guitar. Results were recorded into a
spreadsheet directly in both metric and imperial units, and graphed.
d. Imperial units of measurement are almost universally used as the primary unit for string tension
data, so this was used for graphing purposes and total tension calculation
e. Ones fingers get quite sore after so much testing.
Observations:
It is noted that Pyramid strings have now reverted back to round cores for their strings, only one set
of hexagonal cored Pyramid strings were tested.
All strings were measured at a number of points along their length to obtain the outer diameter and
for wrapped strings the core was also checked in this manner.
Once strings were removed from the rig they were kinked at both ends, as anybody changing strings
would see when removing a string from a tuner string post, as such the testing proved to be
somewhat destructive by method.
6. RESULTS and INTERPRETAION
The results of tension testing are presented in the Appendix for the reader to interpret and utilise as
they see fit.
Tension data is tabulated for each individual string in Pounds of Force (Lbsf) and also in Kilograms
of Force (Kgf).
A further test was carried out and tabulated for some strings, whereby the string was deflected
downward 2mm to simulate the string being fretted and that tension figure is also presented. It can
be seen that additional tension was negligible with respect to the amount of additional tension that
the guitars neck connection must withstand. This could seemly weight to a study carried out by Bob
Benedetto into the ability of humans being able to perceive tension differences through their finger
tips.
The key figure for consideration by the reader is the total tension for any given set of strings tested,
as this is what the instrument has to withstand in practice
For each set of strings a complimentary polyline-fitted graph is provided that depicts the individual
string tension and provides a level of insight into the balance of the strings in each set.
The overlay graph provides a good visual comparative tool for seeing the relative tension between
all sets tested.
Prepared by: Simon Edwards Page 4 of 4 Date: 20/05/2012 File: 140526 String Tension Paper Rev Initial Issue SRE
7. CONCLUSIONS
It can be seen that in practical terms there is very little difference in tension for the plain strings of
the same nominal gauge, regardless of manufacturer. However there are some notable differences
amongst the various types and makes of wound strings.
The Octave strings for the A and E strings have a relatively significant impact for all sets.
It may be argued that most of the gauges tested are too high in tension for valuable vintage
instruments. Clearly the extremely light gauged 0.008” to 0.032w” set of vintage Maxima strings
(Rickenbacker Redbox set) tested applies a significantly lower tension to an instrument.
Intonation of different gauge string sets is not addressed within this study, however there are many
articles available via the internet on the issues associated with varying string gauge pairs and twelve
string guitars.
A significant body of string data now exists that allows custom sets to be assembled and informed
decisions to be made by owners of valuable vintage instruments.
8. FUTURE EXPERIMENTAL CONSIDERATIONS
It would be highly desirable to be able to test a set of vintage Maxima or Selmer nickel flat wound
strings, as would have been commonly fitted to the early 12 string models by the instrument
manufacturer in the 1960’s. The effects on tension due to age of such old strings is another area of
debate, that will not be entered into here.
Further testing of alternative and/or custom sets may take place and be published in the future. This
would be desirable to allow a larger number of custom gauge sets to be deduced from the individual
string data available.
Another worthwhile test data set may be to re-test the most popular 0.010 sets tuned down in pitch
by half a step E-flat, which is not an uncommon practice amongst owners of vintage 12 string
instruments, to determine how significant the drop in tension would be.
Requests from third parties for testing to the same methods as above, may be considered on the
basis that strings are supplied.
It would be interesting to repeat this experimental process for a number bass guitar string sets.
Simon Edwards and Karl Teten, May 2012.
[DOCUMENT ENDS]
RICKENBACKER ELECTRIC 12 STRING SETS CONSTRUCTION ANALYSIS (Selected Sets Only)