S O N I C R E S E A R C H I N C.
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Tuning Pure Intervals with the Turbo Tuner™ ST-122
January 13, 2007
The Turbo Tuner model ST-122 is a versatile device that can be used in a number of ways
to tune a musical instrument in pure intervals. There are three ways of tuning in pure
intervals using the Turbo Tuner: 1) Setting the tuner to the root note, 2) Creating a
custom open tuning, and 3) Creating an alternate temperament.
Tuning Using Harmonics of the Root
Because the ST-122 is a true strobe tuner, it will respond to harmonics of the note it is
tuned to as well as the fundamental. When the tuner is operated in automatic mode, it
measures the fundamental of the note and adjusts the strobe display to show one cycle of
the note. The pattern in the strobe display will show one group of LEDs that rotate to
indicate if the note is sharp or flat. The display will look something like this:
SHARP
pattern rotates right
FLAT
pattern rotates left
The tuner also displays harmonics of the note it is set to. This can be used for tuning pure
intervals by putting the tuner in manual mode and setting it to the root note. Harmonics
of the root are displayed as multiple groups of illuminated LEDs. The displays for the 2nd,
3rd and 5th harmonics are shown below.
Second Harmonic
(Octave)
pattern shows 2 groups
Third Harmonic
(pure 5th)
pattern shows 3 groups
Fifth Harmonic
(pure 3rd)
pattern shows 5 groups
AS an example of how this can be used, consider tuning a slide guitar to an open A
chord. The guitar strings are tuned as follows:
Tuning Pure Intervals with the ST-122
January 13, 2007
Open A Tuning on a Guitar
String
Note
1
E4
2
C#4
3
A3
4
E3
5
A2
6
E2
The 2nd string, C#4 is an interval of a third from the root note of A, and the three E's are
an interval of a fifth from the root note of A. After getting the guitar approximately in
tune, you can put the Turbo Tuner in manual mode and set the note to A1, and tune the
2nd string (C#). The pattern in the strobe display will show 5 groups, and you simply
tune until the pattern is stationary. The same setting of A1 can also be used to tune the
3rd and 4th strings as well.
Many guitars put out a second harmonic that is stronger than the fundamental, and in
these cases, using A2 instead of A1 will give a better display. For the 6th string, you may
find that A0 gives the clearest display. Also, if the guitar is putting out a lot of harmonics,
try backing off the tone control and/or plucking with the side of the thumb instead of a
pick, and try plucking closer to the center of the string (12th fret).
This method of tuning will only work with a true strobe tuner such as the ST-122 or a
rotating disk tuner.
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Tuning Pure Intervals with the ST-122
January 13, 2007
Creating A Custom Open Tuning with Pure Intervals
The Turbo Tuner allows you create custom open tunings and offset each note in the
tuning by up to 50.0 cents. When creating the tuning, offset the pure thirds by -13.7 cents
and the pure fifths by +2.0 cents.
Here are the notes you would enter into the tunings for open A, E and G.
OPEN A
String
Note
Cents Offset
1
E4
2.0
2
C#4
-13.7
3
A3
0
4
E3
2.0
5
A2
0
6
E2
2.0
String
Note
Cents Offset
1
E4
0
2
B3
2.0
3
G#3
-13.7
4
E3
0
5
B2
2.0
6
E2
0
OPEN E
OPEN G
String
Note
Cents Offset
1
D4
2.0
2
B3
-13.7
3
G3
0
4
D3
2
5
G2
0
6
D2
2.0
Alternate tunings are accessed using the MODE key on the front of the Turbo Tuner. It
only takes a minute to program in a new tuning, and it's there whenever you need it.
If you have questions about this or any other tuning related issue, please feel free to call
our tech support department at 800-811-0272 ext. 2.
The Turbo Tuner™ model ST-122 is made in the USA by Sonic Research Inc.
Sonic Research Inc.
800-811-0272
www.turbo-tuner.com
Copyright © 2007 Sonic Research Inc. All rights reserved. Turbo Tuner and True Strobe Technology are trademarks of Sonic Research Inc.
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