Extended 7-String Guitar Raga Guitar Just Intonation 18-tone 11-limit

Tantrakari Guitar

The Tantrakari Guitar was completed in February of 2016 by El Dorado Hills CA luthier Waylin Carpenter. The soundboard is sitka spruce and the back and sides are madagascar rosewood. There are five playing strings (nylon) tuned C2, G2, C3, G3, C4 or sa, pa, sa, pa, sa; two chikari strings (nylon) tuned in unison to C5 or high sa, and eight sympathetic strings (steel) with a jawari bridge.

This instrument has the flexibility to modify its sa or tonal center by changing the string tension. The range is from Bb2 - E2. In addition to the four octave range, there is a five-limit just intonation fingerboard to accurately produce the pure intonation practiced in Indian classical music. The tuning ratios are: 135/128, 9/8, 6/5, 5/4, 4/3, 45/32, 3/2, 8/5, 5/3, 16/9, 15/8. I have the ability to perform the divine ragas of India with most other Indian instruments.

Watch an introduction to the Tantrakari Guitar

Tantrakari Guitar

Extended 7-String Guitar

I worked together with guitar luthier Greg Byers on the internal and external design of this instrument. The 7th-string is a lower string and tuned to an "A" or "G" beneath the low "E"-string and has two extra frets past the nominal nut position, making a longer scale length of 729.6 mm. A sliding capo on the 7-string enables the player to stop the string on the first five frets. The 1st-string has 22 frets or a high "D." This instrument has one octave more melodic range plus an expansive harmonic/contrapuntal facility. I use this instrument for composing and transcribing in the classical music genre.

Currently, I am playing a 632mm scale built by Waylin Carpenter.

Watch an introduction to the Extended 7-String Guitar

Extended 7-String Guitar

25-String Raga Guitar

Luthier Scott Richter built this instrument. The Raga Guitar is a hybrid of an extended 7-string guitar and the Indian instrument, the sarod. There are 7 playing strings, 12 sympathetic strings, 2 chikari, and 4 jawari strings. The Raga Guitar utilizes a 5-limit just intonation fingerboard. Indian classical music has a new offspring.

Watch an introduction to the Raga Guitar

Note Name Ratio Cents
E 1/1 0
F 135/128 92
F# 9/8 204
G 6/5 316
G# 5/4 386
A 4/3 498
A# 45/32 590
B 3/2 702
C 8/5 814
C# 5/3 884
D 16/9 996
D# 15/8 1088

Raga Guitar


Watch Matt talk about the Raga Guitar in this video clip:

low quality | high quality .mov

Click the picture at left for a high resolution view of the Raga Guitar.

The 18-tone 11-limit just intonation guitar

In early 2010, I had Scott Richter build a 5-limit just intonation fingerboard on a 6-string guitar built by Greg Byers. About 6 months later I decided to add two more tones to the existing fingerboard; this transition allowed my craft to transition into 7-limit J.I. In January of 2013, I was deeply moved by the auspicious quality of 11-limit J.I. and had Waylin Carpenter add four more tones to the guitar.

This instrument has: two minor seconds, two major seconds, two minor thirds, one major third, one perfect fourth, two augmented fourths, one perfect fifth, two minor sixths, one major sixth, two minor sevenths, and one major seventh. There are three Pythagorean (3-limit), eight 5-limit, three 7-limit, and three 11-limit ratios.

Here are the ratios in a strait line; "E" is the fundamental tone: 1/1, 33/32, 16/15, 11/10, 9/8, 7/6, 6/5, 5/4, 4/3, 11/8, 45/32, 3/2, 14/9, 8/5, 5/3, 7/4, 9/5, and 15/8.

The 1st string contains all of the 18-tones; the 2nd string has 15-tones (minus11/8, 11/10, 14/9); and the lower four strings are set in 7-limit J.I. with 14-tones (minus11/8, 11/10, 33/32, 14/9). Everything above the 2/1 (12th fret) is set in 12-tone 5-limit J.I.

Watch an introduction to the 18-tone 11-limit just intonation guitar