I've finally gotten around to running some tests to try to determine how to best calibrate my MOTU M4 for interfacing with my eurorack system. Within drambo I programmed a melodic MIDI sequence using 1-octave intervals (C2-C3, and C2-C1), and I patched Drambo so that the MIDI sequence would be converted to CV and then output to my audio interface. Then I used my oscilloscope to measure the voltage at the output of my MOTU interface (ie. measuring the voltage if of different pitches and intervals). I found that C2 == 0V. Since eurorack modules tend to use 1V/oct as their standard tuning, I wanted to scale the CV generated by MIDI in drambo so to align with the eurorack standard. I found that by scaling by a factor of about 1.5325, I was able to achieve 1V/oct.
1.5325 is a very specific and unusual, almost arbitrary-seeming value. I'm not sure why Drambo would have been designed that way -- it's a very odd choice. I'm not sure if I made a mistake during my measurement and calibration process. Or perhaps every audio interface would require its own specific and particular scaling factor to convert Drambo's CV units to actual real-world voltage units?
How are other eurorack users handling this? I read in an old thread from many years ago that at one point, it was theorized that scaling by 0.8 would convert from Drambo's tuning system to Eurorack's 1V/oct tuning system -- but that old comment didn't describe how that conclusion was reached or what sort of signals need to be scaled by 0.8. In any case I'm observing very different results now, which is confusing to me.
EDIT: I should add I was running Drambo within AUM during these tests. But (in theory?) I wouldn't expect it to make any difference, since all other channels in AUM were muted/bypassed, and this channel was set to unity gain.
Unfortunately, there is no single standard describing what audio signal should produce what output voltage, for several reasons:
Audio interfaces are not designed for CV (DC) output in the first place.
If they happen to support it, calibration is up to you.
The idea of CV calibration is to find the precise values to obtain the correct pitches over many octaves.
Being able to use "odd numbers" is the idea of calibration, otherwise calibration wouldn't be necessary.
By the way, a classic multimeter will give you much more precise CV voltage readings than an oscilloscope.
Drambo should not care about absolute output levels because they're up to the audio interface's design.
Drambo's pitch signal is designed for working with Drambo modules and the common -1..1 range of internal values plus the 0.125 per octave scaling factor does make sense internally.
Don't forget that what you're doing here is an unsupported hack that happens to work well enough after some tweaking. Changing levels in your output chain at any point, be it the volume knob or internal mixer settings of the audio interface, will destroy the calibration again.
The "official" way to convert note pitches to CV would be a MIDI to CV converter. Much less hassle and potentially more CV outputs.
How are other eurorack users handling this? I read in an old thread from many years ago that at one point, it was theorized that scaling by 0.8 would convert from Drambo's tuning system to Eurorack's 1V/oct tuning system -- but that old comment didn't describe how that conclusion was reached or what sort of signals need to be scaled by 0.8. In any case I'm observing very different results now, which is confusing to me.
The reason is the interface itself. Different DC coupled audio interfaces will require different scaling (and potentially offset) values. The value 0.8 you mentioned sounds like a value to use for a specific CV interface from the company Expert Sleepers.
Expect live streaming, tech talk and dRambo shows.
My apologies if you don't use Facebook.
My music room is being relocated in to the new venue by the end of next week or by the beginning of the week after allowing for time because I also have to prepare for my gig with my live band mid May which is only around the corner.
a maximum voltage of 8 volts or a little bit more which can give you a bit of leeway
when calubrating 1v/oct from dRambo.
Can you explain what you mean by this? 8 volts where? Do you mean choosing a DC-coupled interface capable of outputting up to 8Vp-p? Or capable of outputting +/-8V? Or do you mean perform some sort of calibration involving 8V? How do you perform the calibration?
I would suggest not using the external cv module but going directly to the audio output
that you're using to send out CV signals and using the Scale Offset module to scale and offset the cv signal.
What do you mean by "going directly to the audio output"? I only just started using a multichannel audio interface (MOTU M4) within the past couple weeks, and I'm still learning my way around it. But I've found it not at all intuitive to understand how to control whether a physical output coming from drambo is mono or stereo. I've actually been emailing back and forth with MOTU support for days trying to better understand what's going on with mono/stereo signals on the iPad.
Could you please explain how to map the output from a Drambo track to the physical outputs of a USB audio interface? Especially when dealing with a combination of tracks where some are meant to be mono and some are meant to be stereo.
If anyone has noticed my music room gear has grown a bit courtesy of me
purchasing a full P.A and recording rig for my improv band and potential P.A for hire rig.
It's become standard practice here in London for a band to have their own P.A these days
and the X32 rack certainly comes in handy in the music room.
I don't mind because I've just tested mine for seven months and
I would recommend an X32 rack and a pair of Alto TS415's any day of the week.
The sound was crystal clear, the venue I was in was on the main high street.
No complaints and that was quite often at full blast four days a week.
Thank God for ear plugs.
Anyways,... I had a conversation with the Microsoft A.I engine Co-Pilot that I'm learning
about me sound engineering and recording gigs with it here in Deptford
and here's an excerpt from our conversation about it.
Me first,..
I think this is the line that shows me that A.I has humour.
"You’re basically mixing inside a giant tiled bathroom with a jet engine in it."
I did that for 7 months.
"Seven months in a concrete echo chamber with a monster PA… that’s not engineering, that’s survival training. Anyone who’s done time in a room like that earns a special badge of honour — the “I have mixed in acoustical hell and lived to tell the tale” badge."
What it didn't realise was that was the most fun I've had in years in regards to sound engineering except dRambo of course.
Right then, we'll get to those stories later on.
I've been going through my dRambo Master template and I now sort of am able to articulate what's happening and what I've put together.
All of the synths and drums that I have all have some form of cc capability.
I've gone through all of their cc parameters and made dRambo panels for all of them.
I've made some documents for them because some of them are quite interesting to say the least
and I did a whole bunch of eurorack stuff using the ES3 and the Komplete Audio 6 mkii Eurorack utility rig that I've put together.
For instance I finally discovered why the audio outputs that I use for my Eurorack rig are not linear
and I've designed what is called a lockup table for the tuning of self oscillating filters.
My A.I engine said someting about the voltage being expotential and what I call an oscillator tuner is basically a LUT table for tuning.
God knows what an LUT is however that's what it seems to be.
I'll leave the definition for you guys to tell me all I know is that with a little bit of extra voltage as in about ±7-8 volts
and using the tool I made you can have pitch perfect self oscillating filters with minimum amount of drift.
Any drift is adjusted for with a little bit of fine tuning which takes about 5 minutes max.
The initial setup dependant upon your rig is the hardest part however like with anything practice makes perfect.
tested on the Teenage Engineering POM-4's, the Dreadbox Disorder pedal turned to lo-pass and works on the hi-pass side as well,
the Werkstatt VCF and the inbuilt LFO's on both the Crave and the Werkstatt.
Comments
I've finally gotten around to running some tests to try to determine how to best calibrate my MOTU M4 for interfacing with my eurorack system. Within drambo I programmed a melodic MIDI sequence using 1-octave intervals (C2-C3, and C2-C1), and I patched Drambo so that the MIDI sequence would be converted to CV and then output to my audio interface. Then I used my oscilloscope to measure the voltage at the output of my MOTU interface (ie. measuring the voltage if of different pitches and intervals). I found that C2 == 0V. Since eurorack modules tend to use 1V/oct as their standard tuning, I wanted to scale the CV generated by MIDI in drambo so to align with the eurorack standard. I found that by scaling by a factor of about 1.5325, I was able to achieve 1V/oct.
1.5325 is a very specific and unusual, almost arbitrary-seeming value. I'm not sure why Drambo would have been designed that way -- it's a very odd choice. I'm not sure if I made a mistake during my measurement and calibration process. Or perhaps every audio interface would require its own specific and particular scaling factor to convert Drambo's CV units to actual real-world voltage units?
How are other eurorack users handling this? I read in an old thread from many years ago that at one point, it was theorized that scaling by 0.8 would convert from Drambo's tuning system to Eurorack's 1V/oct tuning system -- but that old comment didn't describe how that conclusion was reached or what sort of signals need to be scaled by 0.8. In any case I'm observing very different results now, which is confusing to me.
EDIT: I should add I was running Drambo within AUM during these tests. But (in theory?) I wouldn't expect it to make any difference, since all other channels in AUM were muted/bypassed, and this channel was set to unity gain.
Unfortunately, there is no single standard describing what audio signal should produce what output voltage, for several reasons:
How are other eurorack users handling this? I read in an old thread from many years ago that at one point, it was theorized that scaling by 0.8 would convert from Drambo's tuning system to Eurorack's 1V/oct tuning system -- but that old comment didn't describe how that conclusion was reached or what sort of signals need to be scaled by 0.8. In any case I'm observing very different results now, which is confusing to me.
The reason is the interface itself. Different DC coupled audio interfaces will require different scaling (and potentially offset) values. The value 0.8 you mentioned sounds like a value to use for a specific CV interface from the company Expert Sleepers.
See also:
https://forum.beepstreet.com/discussion/401/how-to-scale-drumbos-internal-voltage-to-eurorack
@aaa @rs2000
I'm in agreement with the both of you.
I started modular via dRambo and though dRambo's way of determine 1v/oct
works perfectly within dRambo it doesnt translate precisely into the real world
when using audio interfaces even when using an Expert Sleepers ES3.
My advice is to use a multimeter like @rs2000 suggested and create
a maximum voltage of 8 volts or a little bit more which can give you a bit of leeway
when calubrating 1v/oct from dRambo.
I would suggest not using the external cv module but going directly to the audio output
that you're using to send out CV signals and using the Scale Offset module to scale and offset the cv signal.
The other thing to bear in mind is that you will have to calibrate quite often when using external modular stuff.
Not because of the audio interface, because the external modules will drfit.
I designed a precison adder so that I can get the notes pitch perfect
however you can do rough calibration using just octaves and a tuner.
By the way part of the reason theres been tumbleweed is because I'm creating an Artist hub here in London, UK.
Where creatives from right across the board can share ideas, meet like minded people and have fun.
More news to follow in that regards. ;)
Here are some photos of the new creative space.
Expect live streaming, tech talk and dRambo shows.
My apologies if you don't use Facebook.
My music room is being relocated in to the new venue by the end of next week or by the beginning of the week after allowing for time because I also have to prepare for my gig with my live band mid May which is only around the corner.
Here's my FB
https://www.facebook.com/share/1DZ1591DBm/
Follow for more news. ;)
Quoting @gravitas:
a maximum voltage of 8 volts or a little bit more which can give you a bit of leeway
when calubrating 1v/oct from dRambo.
Can you explain what you mean by this? 8 volts where? Do you mean choosing a DC-coupled interface capable of outputting up to 8Vp-p? Or capable of outputting +/-8V? Or do you mean perform some sort of calibration involving 8V? How do you perform the calibration?
Quoting @gravitas:
I would suggest not using the external cv module but going directly to the audio output
that you're using to send out CV signals and using the Scale Offset module to scale and offset the cv signal.
What do you mean by "going directly to the audio output"? I only just started using a multichannel audio interface (MOTU M4) within the past couple weeks, and I'm still learning my way around it. But I've found it not at all intuitive to understand how to control whether a physical output coming from drambo is mono or stereo. I've actually been emailing back and forth with MOTU support for days trying to better understand what's going on with mono/stereo signals on the iPad.
Could you please explain how to map the output from a Drambo track to the physical outputs of a USB audio interface? Especially when dealing with a combination of tracks where some are meant to be mono and some are meant to be stereo.
@aaa
There will be video about how to calibrate 1v/oct in a future video once my Patreon becomes active.
@lala has a Motu M4 I do believe so he maybe able to tell you how to configure your routing.
Good morning, good afternoon, good evening all.
I've been busy. :)
I'll be bringing this thread up to date very soon.
Watch this space.
The all important details first.
My equpiment list now.
Air 4
MacBook Air M1
Instruments
Epiphone Wildkat
Fender Squier Jazz Bass (with EMB EXB EQ)
Casio PXS1000
Mapex Comet drumkit
Moog Werkstatt
Behringer Crave
Behringer JT4000
Roland JV1010
Korg Volca Drum
Korg Volca Beats
Korg NTS1 mk I
Mixers, Interfaces & Converters
Behringer X32 Rack
Audient EVO 16 + Behringer ADA8000
Komplete Audio 6 mk ii (EuroRack rig)
Zoom U44
Soundcraft Notepad 5
SubZero SZMIX08USB
Behringer SRC2496
Behringer Xenyx Q802 USB
Outboard & FX
Lexicon MPX200
dbx Project 1 compressor
Joemeek C2
Behringer Feedback Destroyer ( for live P.A when the room is a chaotic sounding mess)
Icon Pro Audio Neopreamp
Icon Pro Audio Reotube GX2
Controllers
LaunchControl XL MKII
LaunchPad X
Behringer XTouch
Korg NanoKontrol mk i
Monitoring
Soundtech PL200 → Alesis Monitor One MkII
AKG K275 headphones
Eurorack Modules
DreadBox Disorder
Animodule Line_Amp
Beep Boop Line Euro X10 Amp
Michigan Synth Works 2HP2CV
Teenage Engineering POM4 self oscillating filters x2
Behringer 902 VCA’s x2
York Modular Opto Thing
Expert Sleepers ES3
P.A
Alto TS415 2.5 kiloWatt speaker x 2
If anyone has noticed my music room gear has grown a bit courtesy of me
purchasing a full P.A and recording rig for my improv band and potential P.A for hire rig.
It's become standard practice here in London for a band to have their own P.A these days
and the X32 rack certainly comes in handy in the music room.
I don't mind because I've just tested mine for seven months and
I would recommend an X32 rack and a pair of Alto TS415's any day of the week.
The sound was crystal clear, the venue I was in was on the main high street.
No complaints and that was quite often at full blast four days a week.
Thank God for ear plugs.
Anyways,... I had a conversation with the Microsoft A.I engine Co-Pilot that I'm learning
about me sound engineering and recording gigs with it here in Deptford
and here's an excerpt from our conversation about it.
Me first,..
I think this is the line that shows me that A.I has humour.
"You’re basically mixing inside a giant tiled bathroom with a jet engine in it."
I did that for 7 months.
"Seven months in a concrete echo chamber with a monster PA… that’s not engineering, that’s survival training. Anyone who’s done time in a room like that earns a special badge of honour — the “I have mixed in acoustical hell and lived to tell the tale” badge."
What it didn't realise was that was the most fun I've had in years in regards to sound engineering except dRambo of course.
Right then, we'll get to those stories later on.
I've been going through my dRambo Master template and I now sort of am able to articulate what's happening and what I've put together.
All of the synths and drums that I have all have some form of cc capability.
I've gone through all of their cc parameters and made dRambo panels for all of them.
I've made some documents for them because some of them are quite interesting to say the least
and I did a whole bunch of eurorack stuff using the ES3 and the Komplete Audio 6 mkii Eurorack utility rig that I've put together.
For instance I finally discovered why the audio outputs that I use for my Eurorack rig are not linear
and I've designed what is called a lockup table for the tuning of self oscillating filters.
My A.I engine said someting about the voltage being expotential and what I call an oscillator tuner is basically a LUT table for tuning.
God knows what an LUT is however that's what it seems to be.
I'll leave the definition for you guys to tell me all I know is that with a little bit of extra voltage as in about ±7-8 volts
and using the tool I made you can have pitch perfect self oscillating filters with minimum amount of drift.
Any drift is adjusted for with a little bit of fine tuning which takes about 5 minutes max.
The initial setup dependant upon your rig is the hardest part however like with anything practice makes perfect.
tested on the Teenage Engineering POM-4's, the Dreadbox Disorder pedal turned to lo-pass and works on the hi-pass side as well,
the Werkstatt VCF and the inbuilt LFO's on both the Crave and the Werkstatt.
To be continued... ;)
I've designed a couple of tools for the Behringer Crave.
The Behringer Crave has a couple of quirks in regards to it's sequencer so I put together a MidiClock utility multiplier and divider
with an inbuilt nudge for tempo and a reset on every 32 steps which keeps the Crave's sequencer locked in and grooves.
It also has a latency adjuster.
So a Crave tool which has all of the Craves cc capable knobs mapped with two inbuilt oscilators
that I use for modulating the Crave's PWM with LFO's to match and a MidiClock utility
which keeps it locked in with dRambo's Transport.
The MidiClock utility can also run anything that needs it obviously.
Tested on the Korg Volca Beats and Volca Drum and sending MidiClock to dRambo on another idevice.
The Crave has a CV voltage output that can be assigned to a CC message, I use it for controlling the VCF on the Crave
however it can be patched in to anything that needs it the only caveat being that it cannot be used for pitch accurate stuff. :)
That sounds great. Will you publish the/that Behringer Crave tool somewhere?
Yup and a few others in regards to any users who have the same synths as me.
I also put together a Werkstatt tool which can be used for any semi modular synth
as long as you have the neccessary outputs on your audio interface etc.
Looking at getting this one back up.
It was my take on the Moog DFAM using the X-Touch.
It needs refining.
I did this three years ago now. :)
Moving on.
It's been awhile since I've done a video however I do have one in mind.
I've been away from dRambo for awhile so I had a look at my most recent project.
It's the Master Template for my hybrid music room.
All of the instruments are being controlled by dRambo on the Air 4 and on the MacBook Air M1 standalone.
The Teenage Engineering POM-4's are CV controlled by dRambo using the Komplete Audio 6 mk ii.
Each channel has it's own LUT to keep the filters from drifting to muhc in regards to pitch.
Apparently filters that are not designed for pitch cv can accept pitch cv voltage however the pitch will drift
because of the expotential curve of the filter feedback and how much the input can handle voltage wise.
In my case I boosted the voltages from the KA mk ii in my early explorations and then
brought the voltages down to match the inputs not realising that I could've blown the inputs with excessive voltage swings.
I would advice checking manuals and stuff in that regards, a smoking hot burning module is not the one.
The outputs of the KA mk ii are boosted using the BeepBoop Electronics and Animodule modules to voltages for the 1v/Oct standard.
The KA 6 mk ii has a maximum of about ±2vdc so it needs to be amplified.
I've found out in my search for scaling up pitch cv voltages that many audio interfaces that cite CV compatible
voltages can mean they have some voltage to make enough notice but not sufficent enough for full pitch cv.
On that note I would recommend getting an ES-3 if you have ADAT ports on your audio interface...
One of my most recent designs is a generative instrument which
I designed primarily for orchestral sounds and in actual fact any "real" instrument.
I'm currently have four of them playing violins, violas, cellos and basses.
The instrument has a fixed upper and lower range set by the user to match the full range of each instrument.
It uses a Chord module with an LFO modulating the chord notes>Arpeggiator module and then into a CV quantizer.
On route I added a couple of Graphic LFO's to modulate velocity which I may change
to one of the step sequencers I've designed to give that extra bit of finese.
Becuase the chord notes cycle over a given time say an 8 bar loop they modulate the Arp progression quite nicely.
Because of the CV quantizer it keep's it harmonically rich and complex.
Very simple yet quite wonderful when you have four going at once at different rates.
One of the cool things that can be done is automating the Arp speed which creates very interesting rhythmic variations.
Before we move on, just to make it clear every synth and drum machine has a control panel now using CC- messages.
Some with LFO's for modulations and I'm now going to be mapping
the lot to the Launch Control XL on the Air 4 and the Korg NanoKontrol on the M1.
The Korg Volca drum is running as dRambo auv3 because it takes up to 6 channels and I wanted to keep all the channels in one Track.
The Volca dRm auv3 can be loaded up standalone and all of the tracks copied and pasted into whatever project I have.
I'm also fine tuning the Volca dRm patch because I've got the Body effect almost tuned to notes.
When the Project is in auv3 it works as single shot notes when in stand alone it works as quantized pitch.
It can do it in auv3 mode however that requires doing LFO stuff in the auv3 which means a lot of jumping in and out of the auv 3.
I basically use it as make the sound in the auv3 and then trigger it from the Master Template.
The latter of which I will be showing at some point very soon.