SID v1.7307b Crazy midi issues when part of a midi chain <-- Please help me!

[codydjango]

Hi - I'm new.  I really hope someone can shine some light on this; I'm pretty much at my end.  Here goes:

From a midi controller, or from ableton live, the midibox sid works pretty well.  Every so often a note will hang or drop.

But if I place the midibox on a chain, I can barely use it at all.  Notes drop and hang everywhere, and others mysteriously appear out of thin air. 

This works:  controller --> ableton live --> Presonus firebox midi out --> midibox sid.

This doesn't: controller --> ableton live --> Presonus firebox midi out --> waldorf q thru --> midibox sid.

If anyone has any ideas, it sure would be helpful...

Thanks

[toneburst]

Sounds like the Q might be the problem, then. Can't think why this would be the case, mind you...

Have you got some kind of MIDI feedback loop going on?

a|x

[stryd_one]

Well, there are two differences there - one is that the Q is in the chain. The other is that the total number of devices in the chain is greater. The way to tell which is the more problematic, is to rerarrnge the chain:

This works:  controller --> ableton live --> Presonus firebox midi out --> midibox sid.

This doesn't: controller --> ableton live --> Presonus firebox midi out --> waldorf q thru --> midibox sid.

What about this:  controller --> ableton live --> Presonus firebox midi out --> midibox sid.  --> waldorf q thru

Regardless, that's probably not relevant: you should not get dropped or hung notes from the SID, under normal conditions. I would be doing some checks on the soldering and maybe components.... I smell another dead opto coming on... Have you got a spare opto to test?

[codydjango]

I'm positive it's not the q; I run other synths through it without a problem.  And I do get some dropped notes on the SID without it, but not nearly as many...

I don't have an opto, but I'll check into it.  And I'll go through all the connections again too, I guess... 

Thanks

[stryd_one]

*facepalm* i missed something - the cables... better try a switcheroo there too.... Try two of them, with just the PC connected direct to the MBSID, and then just the controller direct to the MBSID (so, four tests all up). That should eliminate or expose a few problems.

[codydjango]

nope, not the cables either; I just tested them.  But I think you might be write about the opto

For a direct connection to a common MIDI device you need to use the MIDI In and Out of the CORE module. The optocoupler behind the MIDI In port decouples the circuit from the other device to avoid grounding loops. The MIDI device “at the other side†has normaly also an optocoupler at the MIDI In.

Such a “common†MIDI connection via optocouplers is the best solution if the MIDIbox should be connected to a computer. This avoids jitter on the analog inputs, and buzzing noise on the audio outputs (relevant for MIDIbox SID and FM)

I do get a buzz, or rather a hum, from the output, but I figured this was because the MBS wasn't grounded. 

BTW, I tried the midibox chained after my dx200 and it performed the same as when it was chained after the q, so I know for sure it's not the q.

so... time to order a opto.

[stryd_one]

Hmm, with an opto in there even if it is failing it will avoid a ground connection to the PC's PSU, so that hum is probably not related to the opto. You may be right about the grounding. It's possible but unlikely that the PSU is playing a part...

Good luck with the opto!