Korg Poly800/EX800 Users

I have two of those dsp-g1 chips.  Just recently was messing around with one.
I have mixed feelings on the sound quality.
The filter isnt all that great and the EG's are not very intuitive to use.

I do have the source code for them..  can easily change the MIDI to any ttl serial info to change parameters..

I designed the GUI for him when he first came out with it on a hackster kickstarter site..


/Blaine

wild :p  have you seen the 80quid flatpack plastic synth that you snap
together?

given the nature of the poly800 DCOs...there isn't a heap of difference
between saw and pulse, and it doesn't do PWM.
ok, i viewed the YT vid. the square sounds a bit squarer,
and the filter sounds a lot like a dsp filter with whistly resonance.
could that just have a role as a bandlimiter to filter out aliasing?

it would be good to get some more audio demos and samples of wave output.
maybe for some of the other versions too, to see which gives the best
output if it's only going to be used for the wave generator part.

i have a MFB synth lite II which is a fascinating little synth, just for the
size. there's some polemic over whether the oscillators are 'DCO's or
'digital oscillators' - whatever the difference would be there ...? does that
imply that people think it's just playing back a waveshape? there is an
excellent youtube vid somewhere explaining precisely how a DCO works,
and demonstrating the difference between different DCO synths, and how
the DCO is clocked. apparently you can have 'analog' DCO and 'more digital'
DCO, and in fact the juno-60 is quite different from the juno106, for example.
(did we see that here?)

anyway: the MFB does ringmod, osc sync. i read some negative criticism about the
nature of these but i don't find them offensive, and with analog VCF and VCA,
the overall 'trip' is very Moog-like, ranging to Roland sound. the main pain with
it, if there is, is the coarse/fine14bit CC implementation, interpolating 2 midiCCs
for msb/lsb.which the RemoteSL won't deal with, for example. the VCF has
exaggerated resonance imo but sounds better than this dsp filter, as would
the korg filter.

for the dsp chip, i can't see any parameters for adjusting the FX,

It was not but a month ago I was messing around with a DSP-G1 chip.  First I got it running on my workbench, then I brought it up to plug into my VST studio to add some reverb/delay.

I'd like to say first that I am not knocking a tiny synth packed into an 8 pin DIP package.  It's pretty impressive considering the memory limitations Jan had to deal with and the features he actually got into it.
But the more I played around with it, the more I wanted MORE from it.

Does it have a sawtooth voice?  Yes.  And it sounds more full with three DCO's and the detune adjusted.  But, the output of the chip seems kind of thin. 
Is it better sound than the Poly?  A little bit.  The saw sounds alot better and the detune effect is much wider.

The BIGGEST ISSUE IS ADSR's do not seem to be logarithmic.  They sound more linear tapered, as do the adjustments when controlled via MIDI CC (FIlter Cutoff control, for example).  Something about those ADSR's had me pretty frustrated...
There isnt any portamento.  Just a Range adjustment to glide the notes manually.


I do have the source code for that chip, it is available on hackster.  But it is only for personal use.. there is not a release for commercial use.

Is it possible to take the code, get a proper IDE setup and tweak things such as the MIDI serial port speed?  Yes.
I've gone thru the code and played with the idea to merge the chip with the HAWK before.
In the end though, I was pretty disappointed in the quality of the DSP chip.  It was fun to play with for about two hours, but then I realized it was not really meant for more than a simple synth.

What I have my eye on now it the Teensy Audio Adapter Board for use with the Teensy 3.0+  family of boards.
I figured on getting the Teensy 3.2 with the Audio board.

Here's links-
Audio Board  $15
PJRC Store

Teensy 3.2 USB board  $20
https://www.pjrc.com/store/teensy3_audio.html



Teensy Audio Library page (with tutorials) 
Teensy Audio Library, high quality sound processing in Arduino sketches on Teensy 3.1



This setup has much potential.  Easy to begin development.  Has a fairly powerful processor on the 3.2 board with 256k of program memory.
It has an expansion memory on the Audio board available for future Wavetable applications.
There is support to use TWO Audio Boards for Quad output.
The USB port can be configured into a MIDI interface.
Built in DAC/ADC's.  It can do both generated sound and process external input.
It has effects built in.
There is an active community and Paul, the designer, is very active in support.
It's Open Source.
It is setup to use the Arduino IDE to build code and compile.. a very popular format that is easy to use.


Those DSP chips seem to be very limited in comparison to the Teensy system.
Might want to check the Teensy out!

Here's a vid of a kid that made a simple synth out of one..
https://youtu.be/KbcNqarBTsI

and another example...
https://youtu.be/MxDHKpysxYs



/Blaine

what about Axoloti ? it has a modular programming interface,
a bit like synthedit - there are some really cool projects on YT,
and only needs 1 pcb, it's all on there. i think price is good too.

On Thu, Feb 02, 2017 at 02:43:46PM +0000, Michael Hawkins korgpolyex800@... [korgpolyex] wrote:

> I've been going that route myself. I have a STM32F4 eval kit and am slowly building the development environment.

"slowly building the development environment"? Really?

sudo apt install gcc-arm-none-eabi gdb-arm-none-eabi openocd
git clone --recursive https://github.com/libopencm3/libopencm3-examples.git
cd libopencm3-examples/libopencm3
make

boom, done.

--
Gordonjcp MM0YEQ

On Fri, Feb 03, 2017 at 01:54:20AM +0000, Michael Hawkins korgpolyex800@... [korgpolyex] wrote:

> Well thanks for those tips and I will surely use them...
> But since I already have Eclipse and ARM running in version Kepler due to plugin compatibility issues with newer versions of Eclipse. I have to be very careful how I go about installing stuff. So that's why it's a bit slow. The other thing is that I want to use lwIP with the STM32F4 but my existing work has been with the F7 and the stm32_flash.ld file needs to be different but the version I have with the F7 is nowhere near what the newer one for the F4 looks like. So I am currently struggling with all of that. I don't want to throw away my existing Eclipse set up because a) I understand it b) I want to reuse tons of my existing code.
> So thanks for the tips, "boom done" I wish!!!
>
> /Mike

Ah righty, okay :-) I just use boring old gcc, Makefiles and atom (been dabbling with vscode because some of the folk at work use Visual Studio and apparently vscode is the editor "engine" from "new" VS?). The F4 is a beast of a chip for the money. I haven't had a chance to play with the F7 yet. I'm not surprised the .ld files are different, given that it sets the memory map for RAM and flash :-)

I'm blown away that I can run eight antialiased oscillators on an F1 that costs about two quid in onesy-twoesy quantities from Farnell. This is flying-car stuff, for sure.

--
Gordonjcp MM0YEQ