MBFM and MBSEQ V4 coupling problem [solved]

MIDIbox FM
1

I can’t exactly figure out where to post this, so let it be here.

I have a very strange bug:

When i connect my LPC17 MBSEQ to MBFM it seemed like there’s no midi data received by MBFM.

BUT! When i connect it via midi thru enabled device (like Midipal or Shruthi) - all ok. When i connect midi keyboard directly to MBFM - all fine. And connection to midi port of PC also gives me good result.

The MBSEQ works fine, being directly connected with Shruti, Midipal and PC.

When i connect midi cable (with other end in the air) to MIDI OUT of MBFM - some midi data appears, but with a lot of dropped out notes.

Non working config:

[MBSEQ]—>[MBFM]

Working config:

[Keyboard]—>[MBFM]

[MBSEQ]—>[MIDIPAL]—>[MBFM]

[MBSEQ]—>[MIDIPAL]—>[sHRUTHI]---->[MBFM]

[MBSEQ]—>[sHRUTHI]—>[MBFM]

[PC]—>[MBFM]

Half working config:

[MBSEQ]—>[MBFM]---->

Scratching my head… :unsure:

2

I’d check the resistors before the output ports. They may be the wrong values and the signal levels could be less than required for MBFM.

I guess MIDI chips are more tolerant than others? and passing it through another device corrects the voltage level.

3

Hehe, sometimes problems have to be formulated in writing. Yes, it’s low voltage related. I’ve look to schematics of Midipal (3.3 v midiout too) and removed/replaced 220 ohm resistors at all outs like schematic.

Now all works fine, but with a little bug (or feature?) - opened and closed HH can’t play simultaneously. Is it OPL3 restrictions or smth wrong with my MBFM?

for example in this case OH somtimes triggered, sometimes not. It’s random alike thing.

OH …*…*…

CH *…*…*…*…

But when there’s no overlapping between them - they played correctly.

OH …*…*…

CH *…*…

4

I think this topic should be moved to MIDIbox SEQ forum. :getlost:

The HiHat question still opened.

5

Here the thread where the MBFM drum behaviour has been discussed:

http://discourse.midibox.org/t/topic/16073

And here the link to a beta version of the upcoming release:

http://www.ucapps.de/mios/midibox_fm_v1_4d.zip

Best Regards, Thorsten.

6

Firmware update is the first thing i did. The bug, i’ve described occurs on 1.4d =(

7

Open and Closed HH can’t be played at the same time, because they share the same voice.

Btw.: similar to a TR808, “good” sample based drum samplers which allow to group samples, and a real HiHat! :wink:

Best Regards, Thorsten.

8

In old tutorial you wrote, that this cant’t played by real drummer, so i think MBFM can. Now everything is clear.

Thank you, Torsten!

9

Every drum machine I’ve used has imposed the open/close hihat restriction. I would imagine most units do this in software, the RY30 I used allowed you to configure the grouping.

As the OPL chip was designed for soundcards I can only assume they didn’t trust the people writing the drivers to implement this feature and so they did it a chip level.

As for why it randomly works and doesn’t work sometimes, MIDI can’t guarantee that events are delivered on time, it’s a serial protocol at a low data rate. The more busy the bus the more jitter you can encounter.