Show HN: Let’s Bend – Open-Source Harmonica Bending Trainer
78 egdels 16 6/8/2025, 4:00:22 PM letsbend.de ↗
Hi HN,
I built a simple harmonica practice app that shows real-time pitch and bending targets for each hole. It helps blues harp players visualize their technique and improve intonation.
No tracking, no ads, open source (MIT).
The app is available on F-Droid and GitHub. You can find more details here: https://letsbend.de
Feedback welcome!
Somewhat related, for any harmonica player who likes to play cross harp for that bluesy sound, and wants to branch out into songs written in a major or natural minor key (e.g. much pop/rock/country), let me suggest the Melody Maker tuning. This gives you a major scale (along with the relative minor) all up and down the harp in the cross harp position.
And you can still bend notes. You just don't have to for the major/minor scale notes.
For example, a High C Melody Maker is perfect for playing Stevie Nicks' vocal in Dreams. The song is in A minor, but the A minor harps from Lee Oskar and Seydel are in a lower register. The High C matches her range.
The song begins with "Now here you go again", and Stevie has a signature vocal bend on the word "go". She starts that word nearly a semitone flat and then slides up to pitch.
On the Melody Maker, that note is on the draw 3, where it is super fun and easy to start with a light bend to mimic her vocal style.
The nice thing is that you don't have to be so precise on your pitch with this bend. You just start low and slide up, like Stevie does.
I used to make my own Melody Makers by retuning a conventional Richter harp. You raise the blow 2 by a full step to get the second note in the major scale, and raise the draw 5 and draw 9 by a half step to get the minor 7ths. So an F Richter harp becomes a High C Melody Maker and is labeled that way when you buy one.
For years, Lee Oskar only sold Melody Makers in five keys, but now they have expanded it to nine keys including the High C and the Bb that I use for the late Songbird's vocal on You Make Loving Fun.
Seydel has always sold their Melodic Maker (same as Melody Maker) in all 13 keys, but their cover design is so different from Lee Oskar and Hohner that I never could switch back and forth without off-by-one-note errors.
(Yes, 13 keys, because there is both a Low C and a High C.)
Oh - how do you retune a harmonica? File the reeds! File off some weight at the tip and it raises the pitch. Scratch off some weight at the attached end and it lowers the pitch. You just need a single edge razor blade to lift the reed out of its slot, a fine point file or other small file, and an instrument tuner like Let's Bend.
1. Don’t start with a wooden harp like marine band. The metal and plastic ones are typically a bit easier to bend.
2. One hole at a time. Ensure you can exclusively blow in a single hole to practice
3. Lower notes are generally easier to bend than higher notes
4. Make an O with your mouth and have the tongue float in the middle. Start by pulling, not pushing, in my experience bending on intake is slightly easier than bending on blowing out.
5. Tighten the lips and decrease the size of the O to increase pull force on the reed to create a bending effect, and also tighten the airflow chamber above your tongue by pulling your tongue back and up, then loosen it by moving your tongue forward and down
This tool looks great for helping improve once you’ve been able to perform the initial bend. Excited to try it out!
One thing to note (pun intended) is that you can only bend the higher of the two notes in a hole. On the lower half of the harmonica, those are the draw notes. But the upper octave switches these around. The blow notes are the higher ones there, and those are the ones you can bend.
Do you know why that is?
OTOH I find the Marine Band Crossover (with a bamboo comb) to be probably the best bending harp out there due to it receiving detailed factory setup.
> Lower notes are generally easier to bend than higher notes
Additionally, you'll probably find a lower key harp to bend better, at least to a point. I feel like an A harp is the sweet spot for bending really well without being so low that it starts becoming difficult. G harps are good too, but require you to dig deeper to get a good bend.
Essentially, match the size of the resonance chamber in your mouth to the note you're trying to bend to. This is different for every note you bend. You can find the right size by making "hissing" noises while breathing in (without harmonica) and matching the pitch.
Here is a suggestion. Display a graph of played-frequency vs time. Then I can compare visually how my bending performance improves over time.