Speaker for MIDI concertina

[caj]

I built a second MIDI box, with a few modifications from the earlier version.  I've now been struggling to find a way to play the thing in a session without lugging around junk and cables like a doofus; ideally, I would carry in the concertina and my laptop bag, do some quick setup, and play.

 

To that end, I built a speaker unit that has the right dimension to slide into my laptop bag.  I did this by buying a 21" soundbar intended for PCs, removed the parts, and made a wood enclosure of the needed dimensions (14.5" by 3" square).  It has the speaker drivers on the very ends, bazooka-ing outward to approximate a concertina's soundstage.  It can run off a battery just fine, and the laptop can run MainStage with the lid closed, so the whole thing can just sit on the case in front of me.

 

The next step is to synthesize a good concertina sound, which really should use the stereo to pan the left and right hands out the left and right speakers.  If I can do that onboard the box and remove the laptop from the equation, it would be a big step forward.

 

[Steve Schulteis]

I'd start with the the sound font in Don Taylor's signature. You could certainly do a lot worse. I'm assuming you'll use a separate MIDI channel for each hand in order to enable your stereo setup?

 

How loud are those speakers? I'll be quite impressed if they can be heard at a session.

 

What microcontroller is your current iteration built around?

[RatFace]

You could just swap the laptop out for an (oldish) smart phone. My old Pixel 3a running audio evolution pro has almost zero (perceived) lag, and is small enough that you could just mount it on top of the instrument itself. Mine will also power the Arduino (over the USB/MIDI cable) and the battery lasts for a few hours. Then you get the ability to switch sound fonts, adjust things like stereo separation, add reverb etc, and record - with no hassle. With the phone attached to the instrument, it becomes a single "thing" - then your speakers can be separate, but if you use headphones (pixel 3a has an audio socket!), it's completely self contained. I know it's cheating, compared to writing your own synth, but it does work very well!

[David Colpitts]

I agree with RatFace's phone suggestion.  While I am using the iPad for my synthesizer and other music apps, they work fine on the cheapest iPhone (mine!) and allow all the amazing options RatFace mentions.  I use ThumbJam, GeoShred, Micheal Eskin's apps, and a bunch of others.  I think most, if not all, work on Android phones, too. I have demo'd with a small roundish KLM brand speaker (designed for fun at the beach, presumably) with the 1/8" headphone jack as the output, which can clip to the belt, and it is pretty good, but I have not had the opportunity to try it at a session.  Have you read/seen about Dualo?  or the duet Striso?  They build all into a small bellows-device-shaped-object, I think.

[Paul_Hardy]

For my Midi concertina, I use an iPad as synthesiser, usually with BS16i  (https://www.bismark.jp/bs-16i) as the software component. Speaker is an Audio Pro T3, connected with 3.5mm jack headphone cable, because of the latency of Bluetooth audio.

 

The iPad is connected wirelessly using a WIDI Jack to the Midi port on the electronics box of the concertina. Pictures and better description in (https://pghardy.net/concertina/lachenal_30566_midi/lachenal_30566_midi.html). 

[caj]

These are all great suggestions, although my goal is to make a set of instructions so that others can build an identical thing to what I have, with a low probability of individual tech support issues.  I have a few ideas for setting up a standard synth that will "just work."

 

For the speaker, however, I found that making it fit my laptop bag is not good enough --- it's still enough assembly and wires that it's somewhat foreign to set up at a session.  My next idea is to just make the speakers part of the case, because the MIDI box is so small that it only takes up half of a small case.  This way I could just sit down, open the case, pull out the MIDI box with one cable going straight down to the case, and play.  

 

BTW Steve, this speaker is quite loud (50W I think), and it definitely exceeds the volume I can achieve with my Crabb.  

[Ryan Galamb]

Doing the speaker as part of the case sounds pretty slick! Bonus points if the case is small enough to sling over your shoulder and walk around with while playing.

 

Would you still need a laptop handy, or would device/case be enough?

 

Either way, I'm excited to try building one myself once you get the instructions ready!

[caj]

On 7/21/2025 at 10:44 AM, Ryan Galamb said:

Doing the speaker as part of the case sounds pretty slick! Bonus points if the case is small enough to sling over your shoulder and walk around with while playing.

 

Would you still need a laptop handy, or would device/case be enough?

 

Either way, I'm excited to try building one myself once you get the instructions ready!

 

I think the more it looks like a regular concertina case, and the more it imitates what happens in a real session, the better.  So no laptop anymore.  If the box can output MIDI one can always interface it with a laptop at home.

 

I'm envisioning a case containing the concertina with the USB/audio cable already attached.  I sit down, open the box, take out the concertina and don't have to plug in anything.   Press an on switch for the speaker/whatever else, wait a reasonable few seconds, and start playing.  Whatever synth is used, it needs to be close to instant-on, and not require any finagling beyond turning it on.  Anything else might interfere with the craic.

 

I'm going to experiment with Raspberry Pi synths to start with, but another option is to skip MIDI and have a native audio out using the Teensy audio card.   I've heard from folks here who tried fluidsynth but with mixed results in terms of responsiveness.

[Don Taylor]

You probably already know this but, while BT audio has an unacceptably long latency, BT midi transmissions have very little latency. 

 

This is because BT audio needs to compress the audio before sending it and then decompress it at the receiver.  It does this to reduce the amount of data that has to be transmitted over a slow BT connection.  This results in latency and loss of fidelity.

 

BT midi, on the other hand, only transmits a series of very short messages ("turn a note on", "turn a note off", etc...).

 

So, if the microprocessor inside your concertina supports BT midi the you could connect your concertina to a synth inside the case rather than inside the concertina.

 

My experience with fluidsynth over BT midi is that it is quite responsive plus there is no additional loss of fidelity.

Edited July 24, 2025 by Don Taylor
Damn autocorrect!

[caj]

On 7/11/2025 at 6:03 PM, Steve Schulteis said:

I'm assuming you'll use a separate MIDI channel for each hand in order to enable your stereo setup?

 

I think that would make perfect sense, but I am crazy, and I just hit upon a ridiculous idea.

 

I've been experimenting with direct reed synthesis (no wavetables) and I've decided to wrap my synthesis code in an Audio Unit that responds to MIDI messages.  The AU code produces stereo audio out, and I realized that instead of using separate MIDI channels for the two hands I can use a single MIDI channel and "hide" the hand in the velocity, sending 126 or 127 for the two sides.   My synth just picks it out and produces the stereo separation, while the instrument still looks like a single MIDI channel to other instruments.

 

I'm thinking this may be advantageous because we also have the problem of two G/A buttons on the left hand, and similar redundancy on the right hand, so I technically need to devote four separate MIDI channels to disambiguate everything --- or I could just use velocities 124/5/6/7, and stick with one channel.  

[Steve Schulteis]

Gotcha, that seems like a reasonable way to handle it. Another approach (which I have in mind for an upcoming project) would be to use MIDI Show Control to identify specific buttons. But that involves additional messages, separate from note on/off, so it's probably not ideal for what you're trying to accomplish.

[caj]

Just now, Steve Schulteis said:

Gotcha, that seems like a reasonable way to handle it. Another approach (which I have in mind for an upcoming project) would be to use MIDI Show Control to identify specific buttons. But that involves additional messages, separate from note on/off, so it's probably not ideal for what you're trying to accomplish.

 

This might also be a useful trick if someone wants slight variations in the frequencies of duplicate notes, if they have a tuning where the pull A and push A (or the two pull As) are slightly off to either produce a wet effect or align better in different keys --- or if you have an English layout with separate buttons for e♭ and d# and you want those notes to be slightly different.  

[caj]

Finally found some time to work on the speaker case.  Here it is with the speaker holes routed and recessed, with an additional hole for a reflex tube.  Approximate outer dimensions 6x7x10 in.

 

This thing is going to be heavy when I'm done, and it's not really going to be very effective as a case:  the thing inside, the actual MIDI concertina, barely needs any protection, while the speakers will be exposed to the outside!   But the goal is not to be a case, but to camouflage all the downstream hardware in a case-like package.

[caj]

With stain and speakers installed.

 

[Clive Thorne]

Looks excellent, but would it benefit from some sort of grill over the speaker?

[caj]

34 minutes ago, Clive Thorne said:

Looks excellent, but would it benefit from some sort of grill over the speaker?

 

Yes, it absolutely would.  I am trying to puzzle that one out right now.  I'm thinking that for transport I can 3D print a few simple solid plastic covers that go over them (similar to the plastic covers that the speakers were shipped with,) to protect the thing from the elements.  When in use, maybe some kind of grille would be possible, but I've decided to wait on this until after I nail down the proof of concept, and figure out if this speaker arrangement is a good idea in the first place.

[SIMON GABRIELOW]

What a pretty box.  I like the fact it can see what it's doing as well..

( The glasses on top look nice addition)!😊

[caj]

Update:  got it working in the lab.
 

 

The case just barely fits everything, and I have yet to add the local synth.  The sound isn't well conveyed by the Youtube video; its "presence" is much better than the last speaker system.