The Official Sequential/DSI Forum

Midi clock weirdness - ERM Multiclock

Midi clock weirdness - ERM Multiclock
« on: January 07, 2021, 12:24:51 PM »
Firstly, I love this synth!  However I am having some weird sync issues with the Pro 3.  I've looked through the previous posts here and nothing seems to cover it, so I've created a detailed bug report. 

The Pro 3 is being clocked via midi din from an ERM multiclock.  The ERM is sent an audio signal from Ableton as it's master clock, on a track that has a -50ms delay.  This means that we would expect any synth clocked by the ERM to need an offset set on the ERM of around +50ms or a little less in order to account for latency.

There is a Prophet 08 also being clocked by the same ERM multiclock at the same time, in order to be in time it's offset is set at +49ms.  There are other synths also clocked by the ERM and all have an offset between +30 to +49 as is to be expected.

The Pro 3 needs an offset of "+1ms" to be set on the ERM in order for it to be in time.  This is weird.

By "in time" I mean that the audio signal that gets recorded in Ableton is on the grid when I use a basic patch with arpeggiator and trigger it with a bar long midi note from Ableton.  For it to be "in time" it must show each note of the arpeggiator as being on the grid in the resultant audio recording.

Pro 3 has latest firmware installed: 1.1.0.  I've tried to get it working with USB midi to sanity check but I can't seem to get it working. I understand there is a bug with USB midi in this version that we're waiting to be resolved.  I've tried power cycling with the USB cable plugged in, still can't get it working.

Ableton set up:  Delay compensation and reduced latency while monitoring are turned on.  All synths have two channels set up: 

1.  a midi channel with an external instrument plugin, these generally have 7-8ms of latency set.  This is where the bar long midi note is triggered.
2. an audio channel that has it's input set as the output (post mixer) of the midi channel.

The reasoning behind this setup is that it allows us to record midi or audio for each synth in the studio.  This setup seems to work fine for all synths in the studio apart from the Pro 3.

Though weird, I can get along with recording audio that's on the grid in this way  - with the ERM offset at +1ms.  However if I then record the midi output from the Pro 3 while it's playing the arpeggiator, the notes all appear in ableton too early, around 50ms too early! 

Does anyone have any ideas what might be going on here, it's driving me crazy!!