Mojo’s beatseqr test drive

I finally got a chance to demo the beatseqr, which my friend Steve was kind enough to loan me. Steve custom builds these little boxes of MIDI joy. Here’s some video I shot giving a brief overview of the features, some info on using it in a Windows environment, and a little old school jungle/drum & bass beat progression I made using the beatseqr.

So what the hell is an LFO anyway?

Pulsing synth lines, frequency sweeping pads, earth-shaking wobble basses. These are a couple of examples of LFO at work. LFO or Low Frequency Oscillator is one of those mystical acronyms in synthesizer jargon that can be somewhat intimidating to new synth users. But at its heart, the LFO is a pretty straightforward concept to understand. In this post, I would like to break it down.

Lower Frequency
Lower Frequency – Middle C (261.63 Hz)
Higher Frequency
Higher Frequency – 2 octaves above middle C (1046.50 Hz)


Sound is produced as a series of waves and the frequency, or rate of wave cycles occurring in a given span of time, is what determines the pitch (note value) of a sound. This is measured in Hertz (Hz). The average human can hear sounds that fall between 20 Hz and 20,000 Hz.

Those booming low sub basses we hear in hop hop and drum & bass usually fall somewhere in the range between 20 and 100 Hz. These are the kinds of basses you “feel” more than hear. Anything below 20 Hz is too low for human hearing. So why would we care about using waves in these ranges?

This is the beauty of LFO. LFO allows you to use its waveform to modulate (control) a parameter of another sound. For example, if we use an LFO sine wave to control the pitch of a different sine wave that we can hear (oscillating at an audible frequency), the pitch of the sine wave we hear will rise and fall steadily. This audible sine wave is now being “shaped” by the lower frequency sine wave, which is the LFO. Modulating pitch in this manner is how siren sounds are produced. Here is an audio example:

LFO modulating pitch

Other attributes besides pitch can be controlled in this manner. Here is an example of amplitude, or volume, being controlled by an LFO sine wave. This gives us that swelling or pulsing effect:

LFO modulating amplitude

These are two of the most fundamental uses. However when used in combination with other synthesizer modulation tools such as envelopes or filters… well, here is where the full power of an LFO can really be unleashed. Here is an example of an LFO modulating a Low Pass filter, on a saw wave (which is richer in harmonic content than a sine wave). This gives us that classic sweeping, phasing effect we all love:

LFO modulating low pass filter

All of the above examples use a sine wav as the LFO. A sine wave has a very smooth up and down shape and thus produces a very smooth up and down sound. But we are not limited to only using a sine wave. Other wavefroms can be used, each with their own characteristic shapes, resulting in their own characteristic sounds. By looking at the shape of the waveform, one can get an idea of what the resultant sound would be.


Triangle wave
Triangle wave

A triangle wave has a linear up and down sound. This results in a smooth up and down progression, even smoother than the Sine when used as an LFO.

Sawtooth wave
Sawtooth wave

A sawtooth features a rise and then a sudden drop to silence.

Square wave
Square wave

A square is merely on or off, kind of like a binary function applied to sound. This switches the sound on and switches the sound off.

Finally, by matching the LFO frequency to the tempo of our song, we can get incredible timed patterns, that almost make our LFO act as a sort of sequencer. Most modern synths or synth software have a sync function that allows you to easily input the timing of the LFO rate. In other words, do you want the cycles to occur on quarter notes, eighth notes or through a whole measure?

So we have seen how LFO is used to alter the attributes of a given sound and how the waveform chosen for our LFO offers different sonic options. By combining multiple LFOs or having the same LFO control multiple synth parameters, some incredibly crazy sounds can be dished up. The LFO is an incredibly versatile and effective tool to liven audio productions. It’s amazing how something we can’t even hear can offer us so much power. Kind of like our imaginations…

TouchOSC controlling a Modular Synth

A Guy Called Tom (yes, that’s his name on Vimeo) is using the TouchOSC app on his iPhone to control a modular synthesizer. Pure Data is doing the heavy lifting, converting the data to MIDI. Here is what he says about it:

TouchOsc iPhone app sending osc data into PureData Extended, where it is converted to midi and sent to the Doepfer MCV24 which converts it to voltage and controls the modular synth.
TouchOsc XY Pad controls the pitch of two Thomas Henry VCO-1 which also crossmodulate each other.
TouchOsc Sliders control Elby Steiner filter cutoff, Plan B Model 10 env cycle speed, Doepfer BBD feedback and delay. Thomas White LPG used in both mode for amplification. Delay is a Stereo Memory Man with Hazarai. Sorry for the video quality, its done using a photo cam.
Using TouchOsc is fun, there is a lot of control right at your fingertips. Actually it can control way more than i have to control 🙂 Really cool app. Disadvantage is the steping in the control voltages that you can hear quite well, especially when controlling the pitch of oscillators. Not sure if its the midi resolution, the mcv24 or the application itself.

This is very cool. I was experimenting with TouchOSC during my Special Projects in Music Technology class last quarter. I was just using my iPod to control some sounds in Pure Data, this is taking it to the next level. Maybe even the level after that.

Controlling external sound from the Ipod with TouchOSC

I’ve been messing around with an Ipod app called TouchOSC which allows me to send data to my computer from my Ipod Touch. I can hook this up to PureData on my laptop so that I can control sound frequency and MIDI information thus allowing the Ipod to trigger and manipulate the sounds on my computer. Right now I am just playing around with this on a basic level, so I don’t have any video of it, but it is working great. Should be able to use Puredata to output MIDI which would then allow me to control my virtual synths or even outboard MIDI gear from my IPOD. All over Wifi.

Rebirth for the Iphone/Ipod/Ipad

Several weeks back I posted about the grand-daddy of analog synth emulators, Propellerhead’s Rebirth, which emulates a Roland TB-303 synth. The 303 is known for producing the “acid” sound in various forms of electronic music and the Rebirth software does a great job reproducing this sound. The Rebirth also provides TR-909 and TR-808 drum machine emulators to provide a nice little mini studio package for those who want to explore these classic sounds. Well now, Propellerheads has ported the Rebirth into an app for the Iphone, Ipod and Ipad!

Tao Compilation Fixes

As a follow-up to my previous post about Physical Modeling Synthesis tools, I am presenting the following fixes that I discovered for the Tao library. The source code can be downloaded from here.

While working with Tao for a project at my university, I had some issues with compilation under Ubuntu Linux 9.04. I was able to resolve the issues and wanted to offer the following tips to anyone else who may be having similar problems. Apparently in GCC 4.3 some of the C++ headers were removed for cleanup purposes. Therefore I had to edit a few of the source files to add includes for <cstring> and <cstdlib> .

The requisite files for adding #include<cstring> are:


Additionally, add #include<cstring> and #include<cstdlib> to:


Other than that the only issues I had were making sure I had all of the right packages installed. Once all that was resolved, Tao ran fine. Hope this is helpful to prospective Tao users.

Physical Modeling Synthesis with Tools

I am currently taking a special projects in music technology class. The emphasis for this session is on instrument acoustics and we are each tasked with a project to build an instrument based on research of the principles and phenomena involved. I will be working in the virtual arena trying to emulate a unique instrument in software that can emulate the physical properties or characteristics of real instruments. This process is known as physical modeling.

I have currently been surveying a variety of platforms to work as the only music programming I have done so far was in Java and a little bit of C# in the earliest iterations of my wii theremin project. I will most likely end up working with Max/MSP as it is a modular, object based system with a graphical interface – and I need to get up and running as soon as possible. I am also looking at the following languages/platforms which I’ve found along the way:

  • Csound – “…a sound design, music synthesis, and signal processing system, providing facilities for composition and performance over a wide range of platforms.”
  • SuperCollider – “…an environment and programming language for real time audio synthesis and algorithmic composition.”
  • PureData – “…a real-time graphical programming environment for audio, video, and graphical processing.”
  • Steinberg’s VST SDK– allows developers to develop plugins that can operate within Steinberg’s Virtual Studio Technology environment.

Now, these comprise just the basic platforms I am looking at to get started and they are just general synthesis and digital sound processing type programming environments. For physical modeling itself, I have discovered the following packages:

  • PMPd(Physical Modeling for Pure Data) – PMPd offers a collection of objects for Pure Data , and also ported to Max/MSP, which provide real time simulation of physical behaviors.
  • rtcmix~– rtcmix is an open source audio programming language written in C/C++, however the component I am interested in is the rtcmix~ object for Max/MSP which the developers have provided.
  • Tao – “… software package for sound synthesis using physical models. It provides a virtual acoustic material constructed from masses and springs which can be used as the basis for building quite complex virtual musical instruments. Tao comes with a synthesis language for creating and playing instruments and a fully documented (eventually) C++ API for those who would like to use it as an object library.”
  • Percolate – “…an open-source distribution of a variety of synthesis and signal processing algorithms for Max/MSP.” Percolate is based on a port of the Synthesis Toolkit, another system I am looking to work with. Unfortunately, the Max/MSP windows port link for this seems to not be working…
  • Modalys– Developed by Ircam, this seems like it would be the holy grail of physical modeling tools for me to work with. Unfortunately, it is for Macs only (although it looks like some folks have tried to get it running in Linux) and to gain access to it one must become a member of the Ircam forums which costs a decent chuck of cash, so this is out of reach for me; at least for the time being.

The following videos show Modalys in action. What is amazing about Modalys is its accurate representation of actual instruments. These aren’t samples or Wavetable lookups, these are synthesized emulations that completely capture the timbre, characteristics and even peculiarities of the instruments, right down to reeded instruments such as the clarinet or saxophone squeaking.


For the past few months I have had a number of people asking me if and when I plan on releasing the code to my AirDeck project. This is something I have been thinking about, but I have a number of concerns. I am not intending to make any money off this project (not even sure if I could), but I know that I would not someone else to run with the code and make money off of it either. Also, because I am using several APIs that were developed by other people, I am not sure what the licensing issues are. So, I am still deciding on how to proceed.

In the meantime, however, I have decided to post an early iteration of this project in applet form. This is a mouse based version, not using the Wii remote, as this is how I initially began coding and testing the project. I will be the first to admit this is somewhat buggy. I am also interested in seeing how this runs as a client applet on other machines over the internet. This is using a beta version of the JSYN api that is supposed to work without any plugin software. It works fine on my machine, but please leave me a note in the comments describing any issues you may encounter. Thanks and enjoy!

Also, this is a java applet, so java must be installed on your machine. Here is a link to the applet page:


Rebirth Museum

Back in 1997, Steinberg released an innovative piece of software called the Rebirth RB-338. This was the first major analog synthesizer emulator and boy did they choose something tough to emulate… the Roland TB-303 bass box, which was initially designed to be a bass accompaniement for guitar players. The TB-303 never really took off in that regard, but like so many things in the technological arena, an alternative use was eventually found, and the early house producers used it to produce what has come to be known as the “acid” sound. These little boxes, now out of prodution, became the rage for electronic music producers and soon were fetching up to $1500.

The popularity of this sound in the mid 1990s prompted Steinberg to develop the Rebirth emulator and they nailed it. The Rebirth sounds very much like the 303 and even features a number of the little nuances so characteristic of the box. Throw in some effects, arpeggiation and an 808 and 909 step drum sequencer and you had a nice little platform to work with. Now of course, analog synth emulators are all over the place and all the classics, including Moogs, Waldorfs and Prophets are well represented by Virtual Studio Technology plugins (another Steinberg development); but the Rebirth is pretty much where it all started.

And the good news, for those who might not already know… the Rebirth is now completely free to download and use.

Korg has released the DS-10 PLUS

As a fan of the original DS-10 synthesizer software for the Nintendo DS, I have to say the new features look pretty cool. This is a great tool for portable composition of ideas as well as learning some of the basics of synthesis. And the touchpad offers and X-Y input mechanism which was very helpful for me as I worked on my virtual theremin project. New features include effects, an expanded number of tracks and improvements in the sequencer and song modes as well as improved performance.

Kaossilator Pro Demo from 2010 Namm Show

The Kaossilator Pro is an upgrade from Korg’s Kaossilator X-Y axis touchpad synth, and it has a number of noteworthy upgrades over the previous version. The Pro now features an SD card slot to save one’s work as well as a USB port to import and export to your computer. This little guy would be great for live performance as well as a portable workstation to generate ideas. It can now also be used to externally control other instruments through MIDI. Check out the demo.


Beatseqr is a hardware step sequencer that offers real time manipulation of parameters from your favorite virtual synths or Digital Audio Workstations. Designed and developed by Steve, an old friend from my DJing days, it is built using the arduino. It boasts some very impressive capabilities such as 4 pattern looping, pattern copying and pasting, and mute and solo… all rolled up into a very intuitive hardware interface. The sliders can be assigned to various parameters of a patch for further tweaking and this is where the beatseqr really shines. Here is some video of the device being used with ReDrum, providing a general overview of the features. There are a number of other informative demonstration videos over at the beatseqr blog.