How to Tune Guzheng
You need to know two things to tune a guzheng: The pitch for each string and the location of each bridge. Okay that’s 42 things. But! To make your life easier below are tuning diagrams for the most common keys in major pentatonic scales. These tunings have the movable bridges closer to the right side than you may see in photographs. This makes the strings easier to press, which helps beginners learn the left hand techniques. It also changes the timbre of the strings to create a more balanced sound with greater emphasis on lower frequencies. This counteracts the tendency for some guzheng to over-emphasize higher frequencies.
Experienced players or those seeking alternate timbres may want to shift the bridges to the left by up to 2 cm.
These diagrams are based on full-sized (64.5”, 164cm) 21-string guzheng.
These charts and diagrams were built by shifting a full sized instrument from the Key of D to each of the other keys and recording their positions. The original Key of D was tuned based on Carol Chang’s Tuning Document. Her and therefore these charts are designed for lower tensions. They are easier to play and less prone to breaking strings. The Dunhuang company suggests adults play with bridges about 2 cm further to the left, demanding a substantially higher tension. This offer more control of embellishments but requires extra care when tuning to avoid breaking strings.
Some string tensions had to be adjusted when moving between certain keys which is not best practice. Then again, most instruments will not be moved through 7 keys in a single sitting.
Your instrument’s length, bridge height, strings, and tension preferences will lead to different distances. Feel free to send your own measurements in and we’ll compile them! For a chart of specific frequencies, see this Piano Key Frequencies file from Vibrationdata.com.
Tuning Step by Step
Check bridge placement
Tighten or loosen notes in small increments
Move bridges for fine adjustment
Video instructions from Sound of China:
1: Check bridge placement
Bridges need to be placed in a recurring pattern of groups of three and two. Think of those spaces as where you would put bridges if we had strings for notes 4 and 7 in our octaves. If we had those extra strings our bridges would fill those gaps, slowly getting farther apart as they go to the bass notes of the instrument. But, since we use the pentatonic scale and don't have designated strings for 4 and 7, we end up with these groups of three and two.
This grouping does 4 important things. 1) It gives you a visual cue to remember which string sounds which note, 2) informs you which key the instrument is tuned in, 3) provides the physical space to change keys, and 4) provides a guide for how much to shift the bridges when changing keys.
Deciding where to place bridges can be done two ways. The easiest is to use a table of approximate values, several of which are provided above. Place a bridge according to the chart, put it underneath the string, and continue with this guide. This is especially useful if you rarely or never change keys.
Alternatively, you can set the spacing manually. I highly recommend setting bridge spacing manually. It will give you a greater comfort with your instrument, increase your understanding of keys, their relationships to each other, the bridge placements required to reach them, and, if done properly, minimize the amount of adjustments you will need to make to string tensions when changing keys. A complete guide is at the end of this page as it is its own tuning process. Check it out.
Back to Step 1: For a 21-stringed instrument tuned in the Key of G, you'll want your bridges positioned something like this:
2: Pre-tightening Strings
If the strings are newly strung or you loosened them before arranging the bridges, lift each string above each movable bridge and tighten the string until it touches the bridge. Lifting the string up allows you to tighten and loosen the string without fear of breaking it. Strings break during tuning because tension concentrates around the movable bridge; lifting allows the tention to equalize across the entire string.
Once strings are tight to the bridge tip and resist your lift, it is time to check the pitch.
3: Check pitch
Using your tuning device, check each string's pitch by plucking its right side. The left side is not tuned.
4: Tighten or loosen strings in small increments
Lift the string a small distance above the bridge to balance the string's tension, replace it, and then make the appropriate adjustment using the tuning pins. DO NOT change a string's pitch by more than a half step between lifts. Forcing large changes breaks strings.
5: Move bridges for fine adjustment
Once the pitch is close, say off by 20 cents or less, lift the string and move the movable bridge itself. Move it to the right to increase the pitch, and to the left to decrease pitch.
And there you go! If the temperature changes or you play vigorously enough, you'll have to move the bridges slightly to retune it. Get comfortable with the process. With a little practice you need never fear breaking a string again.
Note: Brand new strings take a few turnings to settle in. Use the tuning wrench to tighten the strings as needed, using the lift technique while keeping the bridges where they are. Once the strings are settled, a process that typically takes 2 weeks of daily turnings, you can resume moving bridges for fine adjustments. If you try to move bridges to settle new strings you'll end up with bridges all over the place.
The Manual or Freehand Method
WARNING: I have yet to get this method to work long term. Something is wrong with this theory. I leave it here for people who wish to experiment, but at present, once I move the bridges back to Key of D positions the spacings prevent further key changes. Read on and experiment at your peril.
The goal of setting bridges manually is to set bridge spaces that will allow you to switch to any key you need without changing string tension. You don’t have to measure any distances, but you do have to remember the tuning pattern or notes.
Only do this with settled strings. Brand new strings require frequent tension adjustments for the first two weeks which will throw this whole thing off. Set an hour aside so you aren’t rushed. With practice it will be faster.
The basic method (covers keys F-C-G-D-A-E):
Place bridge #1 at a comfortable distance from right fixed. Tune to D6 with a tuning wrench.
Move bridge #1 to left until the string’s pitch drops by a half step.
Place bridge #2 to the left of earlier bridge, close but not touching.
Tune bridge #2 to C6.
Repeat steps 2-4 with the rest of your bridges. Follow the notes in the graphic above: tune to D, C, A G, F; move to drop pitch one half step, place new bridge.
Once all your strings are set, you’ll have to move a few to set an actual key. See the Key Table for reference. No tension adjustments should be necessary, and you should have enough space to move bridges to wherever they need to be.
Bonus: There are similar pattens you can follow to cover 7 and 8-key ranges, but they are a bit more complicated. In short: 7 keys covers (Bb-F-C-G-D-A-E) and 8 keys covers (Bb-F-C-G-D-A-E-B).
Whereas for 6 keys you have these two steps:
2. Move a bridge to the left until its pitch drops by half a step.
4. Pitch jumps between bridges: 1-2: Half 2-3: Whole 3-4: Half 4-5: Half 5-6: Whole
Fo 7 Keys you have:
2. Move bridges until their pitch drops accordingly: 1: Half 2: Half 3: Whole 4: Half 5: Half (repeat).
4. Pitch jumps between bridges: 1-2: H 2-3: H 3-4: H 4-5: H 5-6: W
And for 8 Keys:
2. Move bridges until their pitch drops accordingly: 1: Half 2: Half 3: Whole 4: Half 5: Whole (repeat).
4. Pitch jumps half step down between each bridge: 1-2: H 2-3: H 3-4: H 4-5: H 5-6: H
Example 21-String in Key of G
1. D6 (1174.7 Hz)
2. B5 (987.77 Hz)
3. A5 (880 Hz)
4. G5 (784 Hz)
5. E5 (659.25 Hz)
6. D5 (587.33 Hz)
7. B4 (493.88 Hz)
8. A4 (440 Hz)
9. G4 (392 Hz)
10. E4 (329.63 Hz)
11. D4 (293.66 Hz)
12. B3 (246.94 Hz)
13. A3 (220 Hz)
14. G3 (196 Hz)
15. E3 (164.81 Hz)
16. D3 (146.83 Hz)
17. B2 (123.47 Hz)
18. A2 (110 Hz)
19. G2 (98 Hz)
20. E2 (82.4 Hz)
21. D2 (73.416 Hz)