A DX7 (Fm synthesis) replacement with Dexed on a Teensy

[ETMoody3]

Done!

Again, nice work, Holger!

[JayShoe]

Done!

Again, nice work, Holger!

Nice work to you, ETMoody3!

How does it sound? Can you make us a video?

[ETMoody3]

Thanks!

It sounds like it should. To me it's a bit more Synclavier than DX7 and there's *nothing* wrong with that.

There's roughly 3000 patches in that sd card, which is delightful fun. ( some slots are blank / init sound )

Yes, sure give me a bit and I'll put something up on youtwab.

[C0d3man]

Hi @ETMoody3,

[...]

Done!

Again, nice work, Holger!

Ahhh, nice case!!! Thanks for showing!

Regards, Holger

[C0d3man]

Nice work to you, ETMoody3!

How does it sound? Can you make us a video?

Sorry that there is no video demo yet. I had once run a MIDI file through the MicroDexed and the MicroMDAEPiano on soundcloud (Drums from RZ-Drummer), no additional external mastering or FX).

Unfortunately, I have absolutely no plan (and very little time) how to make a really good video that shows the synths in action.

I'm currently working on a TouchOSC->MIDI bridge, so that I can control the MIDI-CCs of the MicroDexed (and maybe its SYSEX parameters) with TouchOSC wireless from a tablet. When this is finished, I could also show you how you can turn various parameters...

[C0d3man]

Hi ETMoody3,

Thanks!
It sounds like it should. To me it's a bit more Synclavier than DX7 and there's *nothing* wrong with that.

Try to change the "Velocity Level" (page 18 in the manual). The "original" sound is when using the value "100".

There's roughly 3000 patches in that sd card, which is delightful fun. ( some slots are blank / init sound )

Yes, sure give me a bit and I'll put something up on youtwab.

There are several more SYSEX sound files flying around on the net. MicroDexed handles 100 banks of 32 voices. You can easily replace them or upload banks/voices via MIDI (see manual).

BTW: I have created a forum for MicroDexed - you are welcome to use it!
Regards, Holger

[lokki]

hi there,

what is the current status of (micro)dexed on teensy4?

i have read several forum topics here, and a couple of things are unclear to me:

what is the "best" solution in terms of DAC?

is the internal DAC the way to go, or should i use a PT8211 or the Audioshield?

i have the audio shield, but no PT8211 at the moment. i am looking for lowest possible latency (one post mentioned bad latency with the audio-shield)
and no crackles of course.

thanks for any insights/advice

[C0d3man]

hi there,

what is the current status of (micro)dexed on teensy4?

There are two new versions:
The dev-branch is working stable with two engines of Dexed (16 voices per engine) and FX. Also there is now an additional E-Piano and a simple (ROM-)Sampler besides a small Sequencer/Arpeggiator (thanks to @positionhigh). There is still a bug in the portamento (glissando) code of MicroDexed and some UI optimizations have to be done before "release".

@positionhigh created a fork and added much more features. He also made a cool video. Currently it is a work in progress...

i have read several forum topics here, and a couple of things are unclear to me:

what is the "best" solution in terms of DAC?

is the internal DAC the way to go, or should i use a PT8211 or the Audioshield?

i have the audio shield, but no PT8211 at the moment. i am looking for lowest possible latency (one post mentioned bad latency with the audio-shield)
and no crackles of course.

thanks for any insights/advice

I am not an expert for this, but IMHO is the question of latency not a question of the used codec. Currently the Teensy audio stack is using a buffer of 128 bytes (which means about 2.9ms audio). In addition there is the MIDI latency. My measurements showed about 4-6ms latency. If you need less latency you have to decrease the audio buffer to 64 bytes. Long time ago I tried this with MicroDexed and it worked. But MicroDexed has grown since then and maybe there are audio objects which may have problems with smaller audio buffers. Reducing the audio buffers may also cause buffer underruns, so you have also to decrease the polyphony.

Regards, Holger

[lokki]

ok, will check it out.

code does not compile on teensy4 because of a NUM_DRUMSET_CONFIG 47 for teensy4, just so you know...

[lokki]

Hi Holger, could you share a more detailed schematic somewhere? The resolution of the one in the build doc is not good enough to read the PIN Names. I ordered a teensy 4.1 now, since the dev code compiles for that I would like to try a minimal setup with two encoders, a LCD and an audio shield. I should have all the parts here...

[JayShoe]

You can open the source file here, right? https://codeberg.org/dcoredump/TeensyMIDIAudio

I've opened it in kicad, but it's an eagle file.

[lokki]

thanks, yes. sorry i was so fixated on finding the schematic in the MicroDexed repository...

[C0d3man]

Take care to use the right version of the schematics:

This is the current version for my PCBs - but for Teensy-3.6:
https://codeberg.org/dcoredump/Teens...yMIDIAudio.pdf

This is the adapter board I designed for using a Teensy-4.1 on top of the Teensy-3.6 board:
https://codeberg.org/dcoredump/Teens...pter-Board.pdf

Regards, Holger

[lokki]

thanks, in fact i am looking at the source code now, to see which pins connect where...

[lokki]

ok, built the minimal version with two encoders, a LCD screen and an audio shield with a teensy 4.1

i uploaded the dev code.

LCD and encoders are working fine, i can navigate the menu. in system there is no EEPROM option, was it removed in dev?
there is no sound output on the headphone out of the audio-shield. i have no jack connected to the line out as of now. my understanding was, that headphone and line-out are always the same signal. right? (not electronically, but what is heard) i uploaded the tone-sweep sketch to test the shield and it works correctly.

in config.h i changed the following lines:

//* AUDIO HARDWARE SETTINGS
//*************************************************************************************************
// If nothing is defined Teensy internal DAC is used as audio output device!
// Left and right channel audio signal is presented on pins A21 and A22.
#define AUDIO_DEVICE_USB
#define TEENSY_AUDIO_BOARD
//#define PT8211_AUDIO
//#define TGA_AUDIO_BOARD
//#define TEENSY_DAC
//#define TEENSY_DAC_SYMMETRIC
//#define I2S_AUDIO_ONLY

that should enable audio-shield output right?

[lokki]

also a funny sidenote: the small "1" and "2" to select the dexed instance are reversed horizontally on my display..

[lokki]

ok, the master version (non dev) works! i get output on the headphone, yeah!

it is only stable though when i use the "faster" compile command, with fastest midi is not working reliably, i get hanging notes and high pitched noises.

[C0d3man]

ok, the master version (non dev) works! i get output on the headphone, yeah!

it is only stable though when i use the "faster" compile command, with fastest midi is not working reliably, i get hanging notes and high pitched noises.

Hm... that's strange.

Can you try to upload one of my pre-compiled firmwares?

[lokki]

sure, i tried your T41, 1.0.15 and i get no sound output. strange since it works here when i compile it myself...

[lokki]

also no sound output with the dev precompiled...

[C0d3man]

also no sound output with the dev precompiled...

Ok, thanks for testing. I will take a look at it.

[lokki]

ok strangeness for the WIN. now i don't get any sound even with my own compiled firmware. very strange.
EDIT: it was in the System Stereo/Mono menu, somehow the firmware upload caused it to be MONO which does shutdown the headphone output...

[JayShoe]

I've opened it in kicad, but it's an eagle file.

I'm sorry, I was confusing this with another project. This is a Kicad project.

[C0d3man]

also a funny sidenote: the small "1" and "2" to select the dexed instance are reversed horizontally on my display..

This is because you may have a wrong initial setup where both engines are set to a maximum of 0 notes, which means "off". The reversed numbers are showing this

[C0d3man]

ok strangeness for the WIN. now i don't get any sound even with my own compiled firmware. very strange.
EDIT: it was in the System Stereo/Mono menu, somehow the firmware upload caused it to be MONO which does shutdown the headphone output...

This is strange. I never tried the headphone output. Setting mono/stereo does nothing special - only a mono-downmix of the signal.