Polyphonic Matrixbrute Expansion... with iOS and some patience

[Processaurus]

UPDATE: AudioLayer has added built in automatic sampling, significantly streamlining this process. see video below.


If you'd like to hear your Matrixbrute play polyphonically, and have an ipad, and a midi capable audio interface, you can build a little multi-sampled synth instrument in about 5 minutes. You need two paid for apps: SynthJacker ($7.99), and AudioLayer ($17.99). SynthJacker is an "auto sampler", it plays midi notes out into your hardware synth, and then records the audio, and automatically cuts the recordings into a pile of audio files that are named in such a way that you can batch import them into a sampler player, such as AudioLayer. It goes up the keyboard and holds each note down for the amount of time you told it to, then slices the recording on the midi note and names it how you like it to be named. AudioLayer is one of the few samplers on ios that is full featured, it seems to be based on Logic's EXS24, and you can batch import a folder of samples into an instrument, and with the individual samples named the way it understands, it can assign the note of the sample right, and span the sample over a few keys, until you get to the next sample.

[Processaurus]

The hardware setup is:

A Matrixbrute
a class compliant audio interface, and power supply
a "Camera Connection Kit" (CCK), which is a lightning to USB adapter, or just a USB C cable, if you have a newer ipad.
a midi cable, if the audio interface has  5 pin midi out, OR if not, a USB hub.
2x 1/4" guitar cables.
Ipad (or iphone and good eyes), with SynthJacker and AudioLayer installed.

You plug all of the things together, run the matrixbrute audio to the audio interface.  If using 5 pin midi to "play" the matrixbrute from SynthJacker, run the midi cable from the audio interface MIDI out, to the Matrixbrute MIDI in.  If you want to use the USB midi on the Matrixbrute, you will need a USB hub, to combine the audio interface and matrixbrute USB cable to the ipad, before the CCK.  The ipad's are particular about how much power they provide, so the audio interface should have its own power supply, or, if using the USB hub, it should be a powered hub with wall wart.

To get SynthJacker set up to sample the Matrixbrute, click the + in the upper left corner, to make a new project.  In the main screen, choose Source>External Instrument.  Find your midi port under "Midi Destination", change your Midi channnel if the Brute is set to a channel other than 1, and pick your audio input.  Name your sound.  Under "Notes", decide the range of the keys you want to sample- hint, C2 to C6 is the middle range of the MxB's keyboard.  Choose how close you want the notes in "Semitones Between Notes"- the more notes you use, the more "analog" it will sound, but will take longer to sample and take up more space on the ipad.  There's no shame in only sampling one note per octave, or, you can do say, a minor 3rd (3 semitones), or go for ultimate analog capture and do every single note!  As well, you can choose to do velocity layers, it will do a separate sampling process up the keyboard at each velocity level you tell it, which can get extensive, but if you use velocity, a few layers can give your sampled instrument better feel.  In the sample player, it can do velocity to volume, or filter (it has its own filter), so no need to do velocity layers if you just need volume dynamics.  If you don't need velocity layers, just pick one layer, at 127 velocity, and it will just record one pass through the keyboard.

Under "Timing", choose how long you want the notes to be able to last.  Don't be afraid to make it long, I like using a little more disk space, rather than having to go in to AudioLayer, and make loop points for the sustain part of the note, in each sample.  Listen to how long your sound's release is, and set "Note Decay" accordingly, so your release doesn't get cut off by the next note.

You can do a dry run, and play the sequence before recording, to see if you set everything up right.  You should be able to hear the matrixbrute playing through the sequence, and the notes lasting as long as you want, and the note release lasting the right length/not getting cut off, and not a ton of empty space before the next note.  Be sure to get a good level on the audio. When you're satisfied, hit record, and it does its auto sampling thing.  Can take a break and come back in 5 minutes (or longer, if you're doing an extensive sampling thing).

Synthjacker stores the files in its own folder in the iOS "Files" app. you can get to this folder from other apps, like our sample player, AudioLayer.

Note, under the settings for SynthJacker there is a part where you can change the naming arrangement, I don’t think I needed to change anything, but left it set to “Patch-Velocity-Note”, and Audio Layer could map the samples automatically, just by looking at the sample’s name.

[Processaurus]

Once the samples have been recorded using SynthJacker, you can build a playable instrument using AudioLayer.  It is like EXS24, or a simplified Kontakt- the main idea is that you map samples onto a keyboard, and then can play the samples with a midi keyboard.  To make multi sampled instruments, you use several samples for ascending notes, so each individual sample is only stretched over a few keys.

To make the instrument from the batch of samples that Synthjacker recorded, in AudioLayer, tap on the name of the sound at the top and in that menu, at the bottom, tap "+Instrument" and name it.  Then, on the main screen, tap in the main field, where you put your samples.  Choose "Import sample".  Find your folder under On My Ipad > SynthJacker > [your new sound's folder].  There should be a set of audio files, with the name of the sound, velocity, and note name.  Tap "Select".  Tap "Select All".  Tap "Open" (not "Done"!).  You have a choice of how it maps this folder of files to the keyboard.  Tap "Auto Map [File Name]".  Watch as it maps all of the samples across the keyboard. 

You can edit multiple (or all) of the sample zones at once if you tap and drag a finger across all of the zones.  The controls are the tiny blue knob in the upper right corner, that's where you can set things up like level envelopes, velocity, etc.  You can do all the samples, or just a layer, or just an individual sample.

Remember to click save (the disk icon by the sound's name)!

Your instrument is ready to play.  You preview it with the miserable little screen keyboard, or you could play it from the Matrixbrute, if you hook up the midi out to the interface midi in (or are using USB).  You could just turn down the volume on the matrixbrute, so you don't hear it playing along with your sampler, or if you have something special in mind, could turn off Local Control on the MxB, and then just use the keyboard as a midi controller to play your sampler.

[Processaurus]

Lots of possibilities with this:  You can layer a sound with the real Matrixbrute sound, like to do a true unison sound, by setting the sampler Voices number to 1.  AL can do a stereo spread to the voices.

You can meddle with the synth as the sounds are recording, if you want, to make the instruments sound different as it goes up the keyboard, or just do a unique thing on a certain note.  No reason you couldn't make a multi instrument with different MxB sounds on different parts of the keyboard, like if you wanted a little gallery of different effects, on each key.  Could alternately get into the velocity, but do a totally different sound for different velocity levels, apart from how you can program the synth's velocity. There are some fun iOS apps, like QuantiChord, is a Midi harmonizer, that does key specific harmonies when you play a midi note. With your instrument you could make big, thick chords from one key press.  I believe you can set Duo Split mode to send different midi notes from the left hand side of the keyboard, you could play the MxB with your right hand, and your sampled sound off the ipad with your left hand.  Could even open a vortex by running the audio out of the ipad into the MxB external audio input, like to do polysynth sounds through real filters and effects.

[Alexandrejoe]

Hello, thnks for sharing.
Do you have any audio/video demo to share with us?

[aWc]

I have been doing a similar thing with my MPC live, which has an excellent and full-featured Auto Sampler.
I have created some really big poly brass sounds with it. When playing back these sounds from the Mb's keyboard, the illusion of having a poly Matrixbrute is pretty awesome!

But your idea is a great alternative...and less costly of course.
The key idea here is "auto sampler". Nobody wants to build polyphonic instruments by sampling every note, velocity, etc, for each individual note!

[Lunatic Sound]

I use SampleRobot, which is more expensive, but since you don't need the IPad and other stuff, not really.

Works great since the update to version 6.

[Processaurus]

Virsyn has added automatic sampling to AudioLayer on iOS. Game changer for the poly matrixbrute setup. You can do everything within AudioLayer. It even will automatically add a looped sustain section for each sampled note.

https://youtu.be/Q_b53zfY_CM

Note, they use the plug in version of the app (“audio unit”), which requires a host, such as AUM or AudioBus, apps that are like mixers/routers for music apps on the iPad. You set AudioLayer in an effects slot and sample the input.

[jneumann]

I've done something similar with Izotope Iris 2. Just sample the waveforms from the MxB (or use the supplied analog synth saw, square, sine, etc.), and then make a patch. You can then map knobs on the MxB to knobs in the software using the learn function, which is surprisingly easy. Then you can twiddle the knobs on the MxB while you play Iris, and it kind of feels like you have a polyphonic MxB that responds immediately to your knob adjustments. It's quite handy and convincing, and you can save your patches in Iris. Of course you can replace the virtual MxB oscillators with any waveform you wish.