Midi clock to gate out HELP

#1

hello good people.
i'm trying to use axoloti as a midi clock to analog clock (gate\trig) converter but having difficulties.
i know the audio outs are AC-coupled so not optimal for sending gates out, but i had success syncing my modular to classic metronome sounds (i used to use octatrack metronome via headphones out to sync my modular to the octa).

first question:
which is in your opinion the best, most reliable midi clock input axoloti object?
i tried some but they all seem to drift and wobble around the clock....

The midi clock must come in via classic 5-pins DIN midi connection not via USB as i will be syncing my set with a guy's groovebox with midi clock out

#2

Hi there,

I got it working quite well /reliably by using a digital i/o pin linked to a rail-to-rail op amp used as a comparator that references a constant low voltage (sufficient to change its output for logic 0 and 1 for 3.2 volt axoloti logic signals.) Op amp: MCP6004 is good. It is powered from the 5V Eurorack rail (so it outputs a solid 0V or +5 V as high and low). This ends up being equivalent to a logic buffer with quite good current drive capability, so you can send the signal to passive mults etc. The comparator simply references (‘compares to’) a fixed low voltage from a divider (you want lower than the 1.65 volt Axoloti midpoint reference but not too low to avoid noise, I think I compare to 1V.

I used small capacitors on the outputs I think, to smooth the edge transitions very slightly to give some additional noise exclusion. It works really well for me and with an MCP6004 you get 4 pins of Axoloti-to-Eurorack gate goodness, so I generally link one to midi clock, and the others to either a multiple or divisor of the clock, or to be gates gate for note events or drums etc. :slight_smile: Happy circuiting!

Edit: Ahh, sorry, I addressed the hardware side without answering your questin about midi clock objects. For me in software there was some finagling to get a desirable outcome and very little info available about how to do this. I do not remember off top of my head in software what I did to get a midi clock going out, will have to invstigate and follow up.

#3

Additional comments

  • use very small smoothing capacitors or you will find that you miss gate events because slow transitions will not trigger some eurorack modules.

    • 5V gate levels I have always found very sufficient for Eurorack. There is no real standard, some modules output 10V or 11-ish V (very hot) gates, some 8V, but it seems like a majority of gate generating circuits out there for Eurorack do output around 5V, which happens to be standard TTL logic level anyhow.

    • the MCP6004 can source enough current to power a high efficiency LED (w 2k series resistor or so) as well as whatever module you ate feeding a clock into. So you can have your blinky indicator lights nearly free of additional effort, if that is a reason to try this.

#4

thanks @scitoast this is really valuable information!!!!
i ended up with this solution:
-clock_rx 24 ppq out
-drj/seq/clk_div set at 24 (to get 1 ppq out)
-timer/delayedpulse to get a trigger delay in order to avoid flamming, even if that means having a greater delay. i don't mind having my "1" on the other guy's "2" because i do very fractalized beats, the structure is pretty amorphous, plus i can manipulate it further on the eurorack rig
-table/play
-out

-table/alloc_16b sdram load on which i load up the sample available for download on makenoise website (to clock tempi)

it works quite well, i have to use the trigger delay because if not the tempo is right but the phase of the clock is always random, so i get random alignment. i hooked up a controller so i can delay the clock by ear and find a good compromise.

it's inelegant but better than a kick in the balls, as we say here :smiley: :smiley:

thanks again for taking the time!
i think i will try your solution in the near future!
best!
g.

#5

Hi dudes

Maybe this subject can help you.

I hope it's not a troll for you
Have Fun