Show HN: Haxophone

javier_cardona · 2022-11-20T17:07:50.000Z

I built this during Covid. When I released it, some of the parts went out of stock or skyrocketed in price, no longer making this an economic DIY project. Now that things are getting back to almost normal, I thought I'd share it here and request feedback. This is a very niche project for people who like the same things I do: saxophones, Rust, mechanical keyboards and the Raspberry Pi.

squarefoot 3 years ago |

You can overcome the RPi scarcity by migrating the code to the Teensy platform, which aside being cheaper and less power hungry than the 2,3,4 RPi, is a lot cheaper and more easily available. Not an easy task since there's no Linux under the hood, but there are some excellent audio/midi libraries to help. They already built commercial-level synthesizers with it. By combining the breath sensor data with other pressure sensors you could end up with a very expressive instrument.

https://www.pjrc.com/teensy/index.html

https://www.pjrc.com/teensy/td_libs_Audio.html

https://www.pjrc.com/teensy/td_libs_MIDI.html

https://www.youtube.com/watch?v=z2674LdYW5I

skybrian 3 years ago | |

I like Teensy but it looks like their boards are either low-inventory or out of stock too:

https://www.pjrc.com/store/teensy41.html

djmips 3 years ago | | |

Says one SKU of 4.1 is available with limit of 5 per person

And meanwhile the 4.0 is in stock in all SKUs with limit of 20! per person. https://www.pjrc.com/store/teensy40.html

This is pretty available. Especially compared to Pi

squarefoot 3 years ago | | |

Also, Mouser expects 712 in stock within one week.

https://www.mouser.com/ProductDetail/SparkFun/DEV-16771?qs=v...

ruleforty 3 years ago | |

Before I’d do any of that would be vibrato. Without it it is a emotionless keyboard with a blowtube.

code_runner 3 years ago | | |

If I had the knowledge/ability/skills to build an “emotionless keyboard with a blow tube” I’d be pretty damn happy. I don’t think a lack of vibrato diminishes what is going on here.

Am open sourced wind synth made with a custom keyboard? Pretty sick IMO

postalrat 3 years ago | | |

I don't know. Looks kinda easy to do vibrato through your blowtube https://www.youtube.com/watch?v=XtsZZKZcNC4

oriolid 3 years ago | | |

It's tremolo, vibrato would be oscillating pitch. Real woodwinds can do both. And yes, Fender got them the wrong way.

schappim 3 years ago | | |

Pretty challenging to do vibrato w/ momentary switches (discrete). For vibrato you need something like flexforce pressure sensors[1].

[1] https://www.tekscan.com/flexiforce-load-force-sensors-and-sy...

tomcam 3 years ago |

> This is a very niche project

rockets to #1 on Hacker News

sph 3 years ago | |

Paraphrasing Frank Zappa, the hacker spirit on this forum is not dead. It just smells funny.

nabakin 3 years ago | |

We are the niche

code_runner 3 years ago |

As the owner of a (recently revived) ewi-usb… I’m really curious about the mouthpiece bit. What kind of analog sounds are happening while playing this? Do you notice that reed age, strength etc are as impactful as on a real saxophone? Do you feel a need to swap mouthpieces for different styles of playing?

I love the idea and ingenuity to make this happen!

bwanab 3 years ago | |

As a sax player who also plays a Roland Aerophone, I have a similar question. Is the mouthpiece a real sax mouthpiece and reed? If so, that means it's making a lot of noise. One of the main appeals of windsynths is that I can play at times when the people in my household (and neighborhood) don't really want to listen to it.

That said, it's a cool project.

javier_cardona 3 years ago | | |

The sounds are synthed sounds (I used fluidsynth) and the haxophone just uses the sound pressure to infer velocity of the notes.

The mouthpiece is optional: you can blow on the neck of the device and will get the exact same sound. But as a sax player, I really prefer to use it with a mouthpiece blowing through it but without making the reed vibrate (so no sound). I find that it helps me maintain proper embouchure and feels more comfortable. And after a solid practice session, I still get that gratifying tingling lower lip feeling.

Thanks for the feedback!

https://github.com/jcard0na/haxo-hw/blob/main/docs/assembly....

xavdid 3 years ago |

This is great! As someone who used to play sax a lot but doesn't have hardware experience, it's 100% the sort of thing I would buy if it were commercially available. Makes sense that it's not (ecommerce is a whole thing), but I don't really have the patience to source all the parts and assemble it.

Awesome project though!

mftb 3 years ago |

I'm not exactly in the target audience, but this is brilliant. Bravo!

rudolfwinestock 3 years ago |

Here are other innovative electronic instruments.

The Eigenharp: https://www.youtube.com/watch?v=9MR5qBtPRrM

The Artiphon Instrument1: https://artiphon.com/pages/instrument1

The Linnstrument: https://www.rogerlinndesign.com/linnstrument

BHSPitMonkey 3 years ago | |

The Commodordion (which also made the HN rounds recently): https://linusakesson.net/commodordion/index.php

chuchana 3 years ago | |

The Soundplane: https://madronalabs.com/soundplane

flipcoder 3 years ago | |

I own a LinnStrument and it's fantastic. I created a custom note layout for it to make it easier to play: https://github.com/flipcoder/linnstrument-wholetone. The firmware is also open source. It feels like the Linux of instruments.

diydsp 3 years ago | |

The Brooklyn Eel: https://youtu.be/huYJa2Du57g

system2 3 years ago | |

Artiphon videos don't play on the browser. They chose some weird player with unknown host... Why...

throwaway413 3 years ago |

This is one of the coolest things I've seen on HN. I am definitely going to try to follow the instructions on this in the near future! I don't even play saxophone, but now I am not definitely going to learn. I would 100% buy one of these, if not 3 so I could give some as gifts.

Thanks for sharing and seriously, awesome project. Almost brings a tear to my eye.

WickyNilliams 3 years ago |

This is extremely cool. Surprised how good it sounds in the example video. Wish I knew enough about hardware to build one (OK, i also wish i knew how to play sax). Shame there's nobody shipping all the parts for assembly at home. In any case this is awesome, and one of the cooler things I've seen on HN recently!

seniorsassycat 3 years ago |

There are some really cool wind synths out there

https://m.youtube.com/@EddieEWI

postalrat 3 years ago | |

https://www.youtube.com/watch?v=OYWxCrz3vmQ

mkl 3 years ago | | |

How is this keyboard related to electronic wind instruments?

postalrat 3 years ago | | |

It has a pressure sensitive mouthpiece. Does it need the keys near the mouth to count?

based2 3 years ago | |

https://aodyo.com/sylphyo/

slmjkdbtl 3 years ago |

This is so cool! Interesting you can use normal mouthpieces. Curious how the sound works, does the reed need to vibrate like a real saxophone, or you just need to blow into it and some air pressure sensor picks up (forgive me I have no hardware knowledge)?

javier_cardona 3 years ago | |

No the reed does not vibrate. It's there to restrict the airflow and to provide a similar embouchure to a real sax. Some more details here: https://github.com/jcard0na/haxo-hw/blob/main/docs/assembly....

pom34 3 years ago |

I had the chance of making one in Oct 2021 following Javier's advices on his docs. This was a lot of fun. I printed the 3 required parts on my Prusa MK3S 3D printer. Perfect at the first attempt. I learned how to weld, not so difficult and I could make it also at first attempt. The MPXV7007DP component was indeed difficult to find at that time, but I could find one at Farnell for 18€ (and Digi-Key at 19€). It seems it's still difficult and expensive to find at the moment (but available at about 25€). The result is very nice. The sound also very good with most of the effects you can have on a real sax. And I love the geek look of this sax.

mdmglr 3 years ago |

Reminds me of the EWI: https://en.wikipedia.org/wiki/EWI_(musical_instrument). Which several people in my high school band would play in the locker rooms.

dmead 3 years ago | |

I have an akai ewi sitting on my desk

amelius 3 years ago |

Since it's using keyboard keys I'm guessing it doesn't have any analog touch sensitivity (?) Not sure if that would be even needed on this type of instrument though.

javier_cardona 3 years ago | |

Yes, there is no analog touch sensitivity on the sax: keys are either open or closed. The pressure sensor is for volume and note attack.

junon 3 years ago | | |

There exist analog keyswitches, have you considered playing with those?

jcard0na 3 years ago | | |

While it would be interesting to play with analog keyswitches, it would depart from the experience of a real sax, where the "half pressed" key is of not much use. And it would dramatically increase the complexity of the design.

But the full design is published, just in case anyone wants to try :)

mkl 3 years ago | | |

I'm really interested in this idea for other DIY instrument purposes.

Razer has keyboards with optical ones, and some people have made them by putting inductive sensors underneath mechanical switches, but I couldn't find any analog keyswitches for sale. Do you have some examples?

How can you deal with a large number of analog inputs to a Raspberry Pi or similar?

junon 3 years ago | | |

I don't remember how many analog input pins exist but a separate circuit that digitizes many analog inputs to a serial stream would be how I'd do it, personally.

zwkrt 3 years ago | |

From what I understand of playing a saxophone the variability would come from the mouthpiece. On a type of instrument like a saxophone the valves should always be cleanly opened or closed.

jefftk 3 years ago | | |

Half fingering is a thing, but very rare and fine to be out of scope for a project like this

jedimastert 3 years ago | |

This is also true of the EWI, all of the keys are just metal plates that detect contact, and also generally true of saxophones (although very much not the case with clarinets, which have open finger holes)

insane_dreamer 3 years ago | |

It seems the keyboard is pressure sensitive (reference to a pressure sensor in the HW section)

seniorsassycat 3 years ago | | |

Pressure sensor is in the mouth piece.

I've always thought saxophone keys were on or off

javier_cardona 3 years ago | | |

Actually the pressure sensor is on the PCB. Pressure is transferred from the mouthpiece through a flexible silicon pipe. You can see the details in the assembly instructions here: https://github.com/jcard0na/haxo-hw/blob/main/docs/assembly....

ninjakeyboard 3 years ago |

My girlfriend knows how to play the sax and I know rust (and am a dj/producer!) - so I starred this and we plan to build it. Thanks for your contribution to our life!

jader201 3 years ago |

The video doesn’t seem to load on iPhone (Safari). It loads a tiny thumbnail, then just spins forever.

Edit: it may be because I’m opening it from the mobile link (which sends the video to Safari), but I tried pulling up the repo directly in Safari, and it shows a whitespace placeholder for the video but that’s it.

javier_cardona 3 years ago | |

FWIW, I just tried it on iPhone and works for me...

poulpy123 3 years ago |

Somewhat related, this guy is making a lot of cool instruments that looks reasonably easy to build https://www.youtube.com/c/NicolasBras

beau_g 3 years ago |

Great work, I am going to fork this into a digital didgeridoo project, or digeridoo for short

archarios 3 years ago |

If you want a really high quality premade thing like this, Johan Berglund is your guy: https://berglundinstruments.mediarif.com/

matthewhartmans 3 years ago |

Love this! Well done OP and thanks for sharing the code!

wilsonnb3 3 years ago |

For those who are more into the “cheap sax like instrument” part rather than the electronic part, you should check out the Yamaha Venova line.

apienx 3 years ago |

So this is how holophonors came about...

klaff 3 years ago |

Are there sound samples anywhere?

simlevesque 3 years ago | |

The video in the repo's readme shows a solo from Stevie Wonder's "Isn't She Lovely"

olivermuty 3 years ago |

Can you do a trombone next so we can play trombone hero with a real trombone? :D

wilsonnb3 3 years ago | |

I bet it would be pretty easy to rig up a PBone or PBone Mini to play trombone hero with

b20000 3 years ago |

any info on kernel config, drivers, rootfs etc used?

javier_cardona 3 years ago | |

It's running vanilla Raspberry Pi OS, alsa drivers and fluidsynth, all configured from the main Rust application (https://github.com/jcard0na/haxo-rs/blob/main/src/synth.rs)