Interfacing dRambo with Eurorack

After some research a thought occurred to me, as I have an ancient blackface ADAT,

which is to use the ADAT D/A's for CV signals and then another thought occurred

to me which is to use the outputs of the ADAT for oscillators and then to run

those signals into filter banks and effects and CV the filter banks using dRambo.


Why use the ADAT's D/A's and not use dedicated modules or even a more recent audio interface?


i. Potentially using something such as the ADAT blackface

could add a different tone as they only have 16 bit/48kHz D/A's.

ii. I've also recently learnt from a couple of my recent projects that taking the signal out

from the iPad running it through some analog circuitry and back again does change

the sound in a pleasing way.

iii. The black faced ADAT's have level meters which I think are quite cool. ;)

Comments

  • Yeah, ADAT is a lot of fun. I need to do more experiments with Drambo and my Expert Sleepers ES-8.

  • @auxmux what is Expert Sleepers ES-8 like for Eurorack?

  • I use it as an audio interface for VCV and I route oscillators and filters through it, just like how you described above. I love it so much that I have two. The second is connected to the iPad so I can use for external fx.

  • @auxmux that’s good to know.

  • edited April 24

    Does anyone know of any non-modular audio interfaces that can do -5v to 5v? The MOTU line can only do -4.7 to 4.7 which is frustrating. Preferably something that isn't super expensive.

    I may end up eventually springing for an Expert Sleeper module, but since I'm using the CV for a non-eurorack synth I was hoping to not go that route.

  • +/- 4.7 is not bad, it's odd, but totally usable. Motu is the one brand I know that DC supported outputs. The newer Personus interfaces might be too, but not much options out there otherwise.

  • edited April 24

    Yea it seems like there isn't much to choose from.

    Problem is with the synth I'm using (Gotharman Urano) the input fixed to -5v/5v and the difference causes frustrations. I maybe should just accept the limitations though 😂

  • Maybe I'm confused, but it's a range, so depending on what you're sending, like CV, it should still be ok? Because you just won't get the max range on let's say a bipolar lfo?

  • Because of quirks in the Urano, the lack of the full range stops me from being able to do things various things, like modulating the level of a signal to -∞ db.

    It still provides a fair bit of use otherwise. I use midi from drambo to the urano for note data.

  • edited April 24

    An alternative to es-8 is fh-2 which can be used for midi to CV. The ranges can set per output and a bit cheaper than es-8.

  • @auxmux

    What about 'Scaling'?, for instance tracking 1v/oct to a CV input on a self resonating filter.

    Say we're using dRambo for the CV signals would it be better to do the scaling in dRambo

    or to do the scaling using a Eurorack module built for the purpose?

  • edited April 24

    If you're sending pitch CV from Drambo itself, I would think that's easier to scale from Drambo itself, since it doesn't require buying another module and you can be more precise than using an external offset.

  • @auxmux thanks, that's what I thought also.

    Whilst I'm deliberating upon whether to get an ADAT interface such as Sleepers or an audio interface

    that has multiple audio ins/outs I'm using MiRack as if I were interfacing with "real" Eurorack.

    I'm finding it quite okay actually, most of the stuff that

    I've learnt through dRambo translates very well across to Modular.

  • Let's discuss scaling, for instance I've got Neo Filter up in MiRack auv3

    and it's proving difficult to scale 1 v/oct to it's CV freq input,

    great for microtonal music but not so great for even tempered tuning or close to.

    One of the things I really like about dRambo is that we can connect the key input into

    almost everything and get correct scaling and pitch, obviously with the appropriate scaling modules.

    In MiRack it's awkward to get the scaling correct as each module has it's quirks as it were,

    this is even with using dRambo modules before they go into the CV inputs of MiRack.

    Knowing these things before hand will make anyone prototyping Eurorack's using

    both dRambo and MiRack much easy to make the transition from virtual to the physical.

  • @gravitas in this case, are you using the ‘external cv instrument’ module to output Drambo pitch CV to MiRack? I believe this module should handle the scaling to bring it up to 1v/oct.

  • @aleyas I'm not using the 'cv external module',

    I'm sending the signal straight from 'key input', direct into the audio ins of MiRack.

    Ah....! Thanks, I'm going to try that, back in a moment.

  • @aleyas bear in mind that I'm hosting MiRack in dRambo so

    the 'external cv instrument' module wont be able to handle the scaling as that requires sending

    the cv signal out and then back via an interface of some sort and I'm trying to do this on one device,

    I could use the Midi module in MiRack but I want to get grasp

    on the methods in regards to scaling dRambo to cv first.

  • This is the simplest way I thought to get cv signals and 1 v/oct

    happening in regards to interfacing with Eurorack via MiRack.

    My first thing is to understand the methods of scaling as the terminology is different from dRambo.

    We don’t need to know about +5/5 volt or +10/10 volt cv signals for instance, if that’s the correct way of writing it,

    so I thought to send the “key input” of dRambo and a “pulse” to trigger the noise generator and the ADSR

    directly into the audio input of MiRack to use with the filter modules in MiRack, the oscillator modules

    track really well using this method.


  • oh right, external instrument goes straight to the interface. I forgot and thought that it had an output.

    i seem to recall that we needed to multiply a Drambo pitch signal by something like 8 to convert it to 1v/oct. I bet @rs2000 would remember.

    I also suppose in some cases it would be alright to just take the midi signal from the track header, and bring that direct to miRack. Than from there, you could use miracks own Midi to CV module (forgot it’s name). Then you could apply slew or other pitch modifiers with miRack modules.

  • Yeah, I'm wondering why not just use midi to CV to control miRack rather than Drambo CV?

  • @auxmux because that’s not the challenge, the challenge is to use dRambo CV.

  • recrec
    edited April 25

    Eurorack is optimised for 10 octaves (10 x 1v/oct = 10v total range). Drambo is optimised for 8 octaves (8 x 0.125 = 1 total range) which is extended for f.e filters to 1.5 total range (you can notice that if your filter fully closed and receiving a typical full range modulation - 1 - it won’t fully open).

    Generally to go from D to Eurorack you will need to scale your DramboCV by 0.8.

  • @rec

    "Eurorack is optimised for 10 octaves (10 x 1v/oct = 10v total range). Drambo is optimised for 8 octaves (8 x 0.125 = 1 total range) which is extended for f.e filters to 1.5 total range (you can notice that if your filter fully closed and receiving a typical full range modulatio - 1 - it won’t fully open)."

    Thanks for this.

    "Generally to go from D to Eurorack you will need to scale your DramboCV by 0.8."

    Good to know.

  • Also, Drambo note CVs (output of MIDI to CV) run from -0.5 (MIDI 0), through 0 (MIDI 48), to 0.823 (MIDI 127). You need to add 0.5 to the note CV if you're looking for a 0-1 range.

  • Thanks for this.

    Very useful for reference.

    It's come in handy in tuning some of the filter modules in MiRack.

    Bodes well for interfacing with Eurorack.


    I'm still having issues with keeping the tuning for the Valerie filter

    so I'm going to keep on doing some tweaking to get it sounding just so.

    The others track really well now.

  • Quick update.

    The "Neo" filter by Lindenberg Research is almost there in regards to scaling.

    What also inspired the recent foray into self resonating filters and stuff was this synth,



    It turns out that it's got a piezo, a cut off filter and some CV inputs n stuff so

    I decided to recreate something similar using dRambo and MiRack using my iphone.

    Quite fun.

  • Anyway.

    As I was saying.

    I've now figured out a way to get the cut filters in tune with the correct scaling.

    It's so obvious really.

    Get the filter/s to self oscillate and then tune them to C3 and then feed the CV inputs

    either the 1 v/oct direct from the module or an actual CV audio signal via the audio inputs.

    Place a VCA in series and adjust the scaling using that.

    Why the VCA and not the CV inputs themselves?

    I was doing this particular activity in stereo so I needed a way to dual gang

    the signal going to the filters rather than adjusting the specific CV inputs themselves.

    Checking dRambo's key signal side by side with the 1 v/oct signal emitted by the module

    in MiRack does actually become the 1 v/oct needed when multiplied by 0.8

    which bodes really well for Eurorack from my perspective.

    This was measured using the "Multivoltimeteo" to look at the voltages.

    The "Multivoltimeteo" also comes in handy when scaling as we can see as well as hear the precise voltages.

  • Quick update.

    I now have a Behringer UMC1820 audio interface.

    I'm going to connect up my ancient ADAT blackface soon which I now know can be dc coupled.

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