I have a customer who thinks that 2.8mm at the 12th fret for the 1st string and 3.6mm for the 6th string is too high for a classical guitar and needs to be lowered. This got me wondering about what the established standards really are, so I did a survey of some of my guitar making books to see what the "experts" say. Here is a little essay that resulted:
What are the established recommended standards for classical guitar action height? This is a survey of recommendations published in a few books and manuals regarding this question. Items are listed in chronological order of publication. My comments are in Square brackets . In addition to the citations here, I reviewed several other books (e.g. Irving Sloane, A.P. Sharpe, Roger Siminoff), where I could not find a specific recommendation for action height.
1. In the book, "How to Make a Classic Guitar", by Joseph F. Wallo, c. 1962, [apparently self published], p. 27, Wallo says, "Height of the first string at the twelfth fret should be 1/8 inch [3mm] and the sixth string should be 5/32 inch [4mm].
2. In the book, "Classic Guitar Maker's Guide", second ed., by H.E. Brown, c. 1967, pub. International Guitar and Import Co., Tulsa, OK, p. 42, Brown says, "The bridge saddle is now trimmed down so that when a string is pulled tight between saddle and nut the height of the strings at the twelfth fret will be 5/32" [4mm; this appears to be the same action for all six strings.]
3. In the book, "Make Your Own Classical Guitar", by Stanley Doubtfire, c. 1981, ISBN 0-8052-3833-6, pp. 106-107, Doubtfire says, "Measure the distance between the top of the 12th fret and the under surface of the first string -- it should measure 3mm. Do the same with the 6th string -- it should measure 4mm."
4. In the book, "Guitar Making Tradition and Technology", by William R. Cumpiano and Jonathan D. Natelson, c. 1987, ISBN 0-8118-0640-5, p. 372, the authors say, "For purposes of this operation [shaping the saddle height], approximate standard twelfth fret clearances on the classical (in sixty fourths) are: 10 9.5 9 9 8.5 8 [4.0 3.8 3.6 3.6 3.4 3.2 mm]."
5. In the book, "Things About the Guitar", by Jose Ramirez III, c. 1990, ISBN 84-87969-40-2, pp. 42-43, Ramirez says, "The action universally accepted for the classical guitar is 3 mm for the first string, and 4.5 - 5.5 for the sixth, measuring the separation between the back if [sic] the 12th fret and the lower surface of the string, that is, the space existing between the two objects, with the guitar correctly tuned."
6. In the book, "Making Master Guitars", by Roy Courtnall, c. 1993, ISBN 978-0-7090-4809-1, p. 306, Courtnall says, "The sixth string must be left slightly higher than the first. The final gap should be between 3.5mm and 4.0mm. The first string is less likely to touch a fret when it vibrates, so the final gap here can be 2.5mm to 3.0mm."
7. In the online Web based instruction manual, "Online Apprentice: 2002 Project: Segovia's 1937 Hermann Hauser" [was located at www.OnlineApprentice.COM
, but this is gone now and replaced by a commercial "portal" site], by David Schramm, c. 2002, in Chapter 24, the author indicates that a "low" action would be 0.100" [2.5mm] and a "normal" action would be 0.115" [2.9mm] for the first string, and a "low" action would be 0.135" [3.4mm] and a "normal" action would be 0.150" [3.8mm] for the sixth string. In a similar set of online lessons, "Online Apprentice II, Make Your Own 1976 Miguel Rodriguez Junior Style Classical Guitar, c. 2008,[now also removed from the Web, he indicates that he uses 2.8mm action at the 12th fret for the first string and 3.6mm for the sixth string for this guitar project.]
8. In the book, "The Guitar Maker's Workshop", by Rik Middleton, c. 2004, ISBN1-86126-707-X, pp. 84-85, Middleton says, "The sixth string should have a clear space above fret twelve of 3-4mm for a student instrument and 4-5mm for a concert instrument. The first string should be 2.5-3mm and / or 3-3.5mm respectively."
9. In the book, "Classical Guitar Making", by John S. Bogdanovich, c. 2007, ISBN 978-1-4027-2060-4, p. 296, Bogdanovich says, "A typical string height for the sixth string over the twelfth fret is 0.140 to 0.145 inches [3.6mm to 3.7mm]. The height of the first string at the twelfth fret is typically 0.125 to 0.135 inches [3.2 to 3.4mm]."
10. In the book, "Making the Responsive Guitar", by Ervin Somogyi, c. 2009, ISBN 978-0-9823207-1-6, p. 150, Somogyi says, "The target action for flatpicked [steel string] guitars needs to be higher: 3/32" for the first string and 5/32" for the sixth, at the twelfth fret. ... The target action at the twelfth fret for the Spanish classical guitar is the same as for the steel string flatpicked guitar, or possibly 1 mm higher. [i.e. 2.4 - 3.4mm for the 1st string and 4.0 - 5.0mm for the 6th string].
11. In the book, "Contemporary Acoustic Guitar, Design and Build, Volume 2; Build", by Trevor Gore and Gerard Gilet, c.2011, ISBN 978-0-9871174-1-0, p. 21-11, the authors say, "For a classical guitar with a standard setup the action should be 4mm for the 6th string and 3mm for the 1st string."
12. From the classical guitar Web site DELCAMP.COM, (viewtopic.php?f=11&t=64845#topic4
), "Luthier's" thread, topic "Frequently Asked Questions About Classical Guitars", by Luthier James Lister:
What is the correct action for a classical guitar?
Normally 3mm at the first string (top E) and 4mm at the sixth string (bottom E). These figures can vary up or down slightly depending on the player, but not normally by more than 0.5mm.
The action is measured at the 12th fret, from the top of the fret, to the bottom of the string.
To Summarize, here is a table of recommendations from these 12 luthier authors, for the action at the 12th fret for a classical guitar, in millimeters (mm):
First string Sixth string
Author Low Normal Hi Low Normal Hi
Wallo 3 4
Brown 4 4
Doubtfile 3 4
Natelson 3.2 4
Ramirez III 3 4.5 5.5
Courtnall 2.5 3 3.5 4
Schramm 2.5 2.9 3.4 3.8
Middleton 2.5 3 3.5 3 4 5
Bogdanovich 3.2 3.4 4 5
Somogyi 2.4 3.4 4 5
Gore & Gilet 3 4
Lister 3 4
The majority seems to recommend 3mm for the action on the first string and 4mm on the 6th string. The extremes are about a low of 2.5mm and a high of 3.4mm for the first string, and a low of 3mm and a high of 5mm for the sixth string. I general it is best to avoid the extremes unless specifically requested by the customer of a custom guitar.