A commenter on the last post informed me of a remarkable fact: for most of the twentieth century, Hohner harmonicas were tuned in just intonation, not twelve-tone equal temperament. This is surprising! Just about every fixed-pitch instrument in the Western world is tuned in 12-TET unless it’s highly specialized or esoteric. The most detailed information I can find on this subject is this post on a Hohner discussion forum. It says that before 1974, Hohner harmonicas were tuned in seven-limit just intonation. This doesn’t mean some weird Harry Partch tuning; Hohner used mostly five-limit intervals along with the harmonic seventh. In 1985, Hohner switched to nineteen-limit just intonation (!) because it gives pure intervals that approximate 12-TET more closely. In 1992, they switched again to a variety of tunings that split the difference between just intonation and twelve-tone equal temperament.
Before your eyes start glazing over, the important thing here is that when midcentury blues musicians like Little Walter Jacobs were playing their Hohner Marine Bands and Special 20s, they were playing in just intonation.
Here’s Little Walter’s classic “Juke” from 1952. He’s playing on a Hohner Marine Band.
The tune is in E blues. The recording is tuned about 27 cents flat overall. I used Ableton Live to bring it up to A440 so I could examine the harmonica’s tuning. A harmonica obsessive named Örjan Hansson created this tuning table for vintage Hohner Marine Band and Special 20 harmonicas. For reference, here are the notes in an A harmonica, which you use to play blues in the key of E:
| Hole | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| Blow | A | C# | E | A | C# | E | A | C# | E | A |
| Draw | B | E | G# | B | D | F# | G# | B | D | F# |
According to Hansson’s table, the widest and most significant deviations from 12-TET in pre-1974 Marine Band tuning are in these three notes:
- G-sharp is tuned 12 cents flat, close to the 5/4 just intonation major third.
- C-sharp is tuned 14 cents flat, close to the 5/3 just intonation major sixth.
- D is tuned 29 cents sharp, close to the 7/4 harmonic seventh.
I used MTS-ESP to make a just intonation “blues scale” using five-limit G-sharp and C-sharp and seven-limit D. Then I put in Little Walter’s melody on an organ and listened to them simultaneously. Hansson appears to be correct; my just intonation scale matches Little Walter’s tuning. For further confirmation, I accidentally played the track with the tuning plugin turned off so the organ was playing in 12-TET, and the tuning clash was unspeakably horrible.
Okay, but wasn’t Little Walter bending his notes to make them go flat? He does bend a lot, but not all the time. During the opening chorus of the tune, he doesn’t bend at all, really, aside from putting a touch of color on the G-sharps. The first really conspicuous bend is at 0:38, when he bends his low E down to a very funky D. At 0:46, he bends a G-sharp most of the way down to G. And at 0:49, he bends B down to various pitches in the B-flat region. But for the most part, he is playing the pitches that the instrument plays out of the box, and those pitches are definitely not in 12-TET.
Not only is it remarkable that Hohner was using a non-standard tuning; they were using a tuning specifically designed to accommodate blues musicians. If you are playing Western European tonal music, you don’t want a harmonic seventh, you want to keep everything in five-limit. I would love to learn more about this decision on Hohner’s part. The most thorough harmonica history I can find is Harmonicas, Harps and Heavy Breathers by Kim Field, and she doesn’t talk about the tuning of historical harmonicas. The closest she comes is on page 184, when she complains about the sound of the equal-tempered Golden Melody. She also praises the “much smoother, sweeter sound” of just intonation thirds, and “that pure seventh chord” you get from the harmonic seventh. But I don’t know if she’s referring to commercial harmonicas from Little Walter’s era, or stating a preference for the custom-tuned harmonicas that people are making and selling now.
So does this mean that the blues generally is based on seven-limit just intonation? Gerhard Kubik argues in his book Africa and the Blues that blues descends from West African traditional musics that tune to the first seven harmonics of a central tone and another tone a fourth higher (like the low E and A strings on a guitar.) I find his argument to be a compelling one, but plenty of commenters on this blog and elsewhere are skeptical. I have been accused of looking for just intonation where it doesn’t exist, like I’m this guy from School is Hell by Matt Groening.
But if the blues is not based on the first seven harmonics of I and IV, then what was Hohner doing making seven-limit just intonation harmonicas? It wouldn’t be surprising if Hohner used five-limit; harmonicas are limited to one key each and don’t transpose, and all those intentionally out-of-tune 12-TET intervals produce unpleasant beating. If Hohner wanted to support people in playing straight harp, that is, playing their A harmonica in the key of A major, then five-limit would be a better choice, something like Ptolemy’s Intense Diatonic Scale. But Hohner wanted to support blues musicians playing their A harmonicas in the key of E blues. For that, you want an in-tune tonic dominant seventh chord. This may not prove conclusively that blue notes are just intonation intervals, but it certainly is a remarkable coincidence.