Triton Taktile: A few more thoughts

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A quick follow-up to my earlier snap review about the Korg Triton Taktile.

I’ve spent more time playing the Triton Taktile and generally remain pleased with many of the on-board preset sounds and the keyboard feel. The only major disappointment is a way to toggle the rotary speaker speed for B-3 organ sounds. Speed changes are an important part of B-3 playing style and I sorely miss this capability. I hope that Korg can find a way to add speed change in a future update. Unfortunately, the Leslie effect seems to be sampled into many of the sounds, so an update of this kind may not be possible technically.

I wanted to register my favorite patches, so I decided to download and install the Korg Kontrol Editor. The front panel procedure for registering favorites is not particularly fiddly, but the Kontrol Editor allows entry in one go and presents a WYSIWYG view on the contents of favorites Set A and Set B. I like to see how the patches are laid out across the buttons and to juggle their order. The Kontrol Editor does the business as you can see in the screen below. The Kontrol Editor leaves tool/keyboard synchronization up to you. When you have something worth writing then you click a button to transfer the edits to the keyboard. When you want to read something back from the keyboard into the editor, then click the appropriate button.

KontrolEditor

The screenshot shows my favorite sixteen patches. Set A is my “church” group consisting of voices that I am most likely to use at rehearsals with the music ministry. Set B is my “jazz/pop” group of voices that are fun for jamming with MP3 backing tracks or even PSR-S950 styles.

If you ever go to use Korg Kontrol Editor on Windows, please note that you must install the Korg USB-MIDI driver first. The install documentation has a small hiccup and doesn’t mention the need for the driver right up front. No biggee, but you will need the driver.

The Korg part of the installation is smooth. The Windows part, however, became a learning experience. A-hem. I had plugged the Triton Taktile (TT) into a USB port before installing the Korg driver. Windows installed some default driver of its own. This is not surprising. However, the Kontrol Editor did not recognize the TT after installing the Korg USB-MIDI driver. The editor has a means of manually selecting MIDI ports and the TT did not appear in the editor’s list of available (connected) ports.

Time for the usual Windows driver-Hell troubleshooting. Before doing anything else, I uninstalled the Korg driver and rebooted.

While searching the Web for a solution, I found several references to the notorious Windows XP MIDI limit. Windows installs a separate driver for not only each different MIDI device (keyboard), but each unique combination of device and physical USB port. Yep, this means that you get two instances of the same driver if you plug your TT (or whatever) into physical USB port A today and into physical USB port B tomorrow! Windows XP remembers up to ten MIDI drivers and if you tend to move your MIDI devices around USB ports, the ten slots get filled up. Then, no more.

There is some debate as to whether this limitation is present in Windows 7 or not. (I’m using Windows 7.) One solution to the problem is to manually remove registry entries for unused (inactive) MIDI devices. Tromping around inside the Windows registry, however, is not a particularly safe or fun activity.

There are two better and safer methods for removing inactive MIDI drivers:

  1. A method suggested by Craig Anderton on Harmony Central. (Search on “windows midi limit”.
  2. The Korg USB driver uninstall utility.

Craig’s method is clear, but requires a little Device Manager knowledge. Basically, you need to execute these two commands as Administrator:

    set devmgr\_show\_nonpresent\_devices=1
    start Devmgmt.msc

Windows launches the Device Manager where you can navigate to the “Sound, video and game controllers” part of the device tree. There, inactive drivers are shown with a greyed out speaker. Right click on each unwanted inactive driver and select “Uninstall” from the contextual menu. Once slots are freed up, you should be good to go.

Or, better yet, try the Korg USB driver utility. This utility program is installed along with the Korg USB driver itself. The uninstall utility displays the unconnected (inactive) MIDI devices and lets you uninstall the associated driver. I installed the Korg USB driver (leaving the TT unattached) and ran this utility on my machine. I selected and removed all of the inactive devices/drivers. Then, I plugged in the TT and voila, the KORG driver and editor recognized the Triton Taktile. All was then good with the world.

Even if you don’t own or use a Korg keyboard, I recommend this utility as a way to work around the Windows MIDI driver divot. Korg really should be commended for writing this utility and making it freely available. As to Windows, I really don’t need any more learning experiences of this type…

Another minor issue is dealing with the 3.5mm (1/8″) stereo output. This output is fine when connecting in stereo to either a 3.5mm or 1/4″ stereo phone input or connecting to two 3.5mm or 1/4″ phone mono inputs — just use the appropriate cable (i.e., TRS to TRS or an insert cable). Connecting from 3.5mm stereo to 1/4″ mono is more troublesome as the right and left channels need to mix down to mono. I received the following reply from Korg USA product support:

You should be ok to connect the Triton Taktile to a mono input by using an 1/8” stereo to a (1/4” or 1/8”) mono cable. I don’t think there are any programs that have sounds panned hard right so all the programs should sound fine.

The HOSA (Livewire) CMP-105 is such a cable. Properly, one should mix down the right and left signals, passing each side through a 1K ohm resistor into a common electrical node (the mono output). You might also want to check out the advice and circuits at Why not wye?

I’m happy to use the CMP-105 as long as there aren’t any long term reliability issues on the Triton Taktile side. The stereo to mono cable does work as suggested by Korg. I will mainly use this solution when driving a mono-only effect like a guitar pedal. Otherwise, there are usually enough available inputs to do a more proper mix down.

Finally, I was curious about the MIDI bank select and program change messages that are needed to select Triton Taktile programs. The TT follows the typical Korg convention: Bank Select MSB is 121 (decimal) for regular voices and Bank select MSB is 120 for drum kits.

The program layout is somewhat schizoid. Korg did not collect all of the drum kits at the end of program list (as Mr. Spock would expect). The drum kits are interspersed with regular voices in the final quartile. Normal voices are assigned banks and program change numbers in the expected fashion up to program number 399, which is the first drum kit. Program number 1 has bank select MSB 121, bank select LSB 0 and program change 0. The program change numbers increase to 127 when the bank select LSB increases to 1 and the program change number rolls over to 0. This continues in an orderly fashion until program number 299 and the first drum kit. After that, the assignment is difficult to enumerate. (Please see the table below.)

I determined the bank select and program change values by monitoring the TT’s MIDI OUT while changing programs through the front panel. If you want to fill out the rest of the table, grab a copy of MIDI OX and monitor the MIDI OUT. Yeah, I’m lazy. 🙂

Program# MSB LSB PC# Program name
1 121 000 000 A. Piano
… … … … …
127 121 000 126 F.Horn Ens
128 121 000 127 Flute
129 121 001 000 Sax Ens
… … … … …
255 121 001 126 Hybrid Brass
256 121 001 127 Blind Brass
257 121 002 000 Reso Brass
… … … … …
383 121 002 126 Brass/Lead
384 121 002 127 PWM Lead
385 121 003 000 Glide Lead
… … … … …
415 121 003 030 Monster
… … … … …
399 120 000 007 Std Kit 1
400 120 000 011 House Kit
401 120 000 015 Psycho Kit
402 120 000 017 Orch&Ethno
403 121 003 018 Velo Hit
404 121 003 019 Gtr Hit
… … … … …
416 120 000 120 Std Kit 2
417 120 000 010 Brush Kit
418 120 000 009 Power Kit
… … … … …

Korg Triton Taktile: Snap Review

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The Korg Triton Taktile has a double personality. On one hand, the Triton Taktile (TT) is a MIDI controller with eight knobs, eight sliders, eight buttons, sixteen pads and a set of DAW function buttons. (These are the specs for the 49-key model, the model that I’m using.) On the other hand, it is a synthesizer with the Korg Triton classic sound engine. Right now, I’m playing the TT as a synth and I will be concentrating on the synth features.

The Sound On Sound review of the Korg Taktile controller (the model without the sound engine) is very well-written and I recommend reading the SoS article for more information about the TT’s control capabilities. I will say that Korg hit my major checkmarks for a controller: a 49-key keyboard with a good action, expression pedal input, sustain pedal input, and TA-DA, a 5-pin MIDI output in addition to the USB-B connector for power and computer/tablet communications. The TT will operate on a portable, rechargeable USB power pack (minimum 5V 1A output) and that is in fact how I’m using it in the studio. The picture below shows the Triton Taktile under battery power. The TT weighs just a little bit over 8 pounds (3.8kg) and is easy on the eyes as well as the back.

TT_with_battery

The TT connects to either headphones or external amp through a 3.5mm stereo jack. All of the connections are made through a panel on the right side of the TT. The output level is sufficient for comfortable listening on Roland RH-A7 headphones, my current choice for head gear.

As you might be aware already, you don’t get a full Triton classic. The TT is not multi-timbral and it does not have combinations (“combis” or layers) and insert effects. However, you can bring up one of 512 classic programs (voices) and play your heart out! There are two system-level master effects (MFX1 and MFX2) that are appropriate for the preset voice, e.g., chorus and reverb on electric piano. The TT is strictly a preset machine as program edits cannot be stored. This hasn’t cramped my act so far, but like any of the TT’s limitations, it could be a deal-breaker. You can save your favorite preset programs into two sets of favorites (set A and set B, each set with eight slots) for quick patch selection.

Hit the dedicated SOUND button to leave controller mode and go to synth mode. The current patch number and name are shown on the nice bright OLED display. Even though the OLED display is small, it is very readable. There are three ways to select a program:

  1. Press one of the program category buttons (assignable buttons F1 to F8). The TT selects the first program in the category or the last selected program in the category. It remembers the last selected program until power-off.
  2. Use the value slider (ribbon) to scroll through the programs. Tap the “+” or “-” at either end of the slider to increment/decrement, or slide your finger along the ribbon to move quickly to a new patch.
  3. Select one of your favorite programs from either set A or set B.

It takes a little practice to get the hang of the slider. Do not take this ax to a gig and expect to select patches on the fly! I recommend setting up favorites and getting the general layout of the patches before hand. Otherwise, an embarrassing epic fail will ensue.

The keyboard feels very good for a controller in this price range. It has a little more resistance than the Yamaha MOX series, for example. I find it quite comfortable to play — it does not feel like a toy. Korg claim that it is the same action as the Krome and I have no reason to doubt them. The pitch bend and modulation wheel also have a satisfying feel. The knobs and sliders are a little bit “light” to me. I don’t have an opinion on the pads as yet.

I enjoy playing this instrument! The knobs and sliders control eight parameters: volume, cutoff, resonance, attack, delay, release, MFX1 and MFX2. Cranking the cutoff and resonance is a real visceral thrill. The two master effects, unfortunately, are very subtle and understated. The TT cries out for a multi-effects unit with distortion and other sonic manglers.

My favorite sounds are the electric pianos, drawbar organs, church organs (!), strings, and acoustic guitar. Korg strings have always had a wonderfully expressive depth and these patches do not disappoint. The electric pianos are very clean. I threw a cheap Danelectro overdrive on the output in order to realize the EP’s full funked-up potential. Oh, for a multi-effects unit, Korg!

The brass isn’t too bad, especially the horns, cornet and flugelhorn. The TT’s woodwinds are pretty naff — yuck. My musical personality is split between liturgical church music and jazz/funk/60s rock. On the church side, I’m disappointed with the oboe, clarinet and other reeds. On the pop side, I don’t often venture into synth territory. However, the HipHopLead patch is great when you feel the urge for Herbie. There are a lot of lead and pad sounds to explore and I’m sure that I’ll find a few other useful patches.

The handbook in the box is helpful, but not sufficient. Be sure to download the parameter guide and the Triton Taktile-specific MIDI implementation chart. Korg could be a little more forthcoming about the MIDI implementation considering that the Taktile series are MIDI controllers for heaven’s sake. The full list of programs is at the absolute end of the parameter guide. I always look through the list of patches for a synth/workstation when considering a purchase and this list is somewhat hidden away at the end of the parameter guide.

Bottom line, I’m happy with the Triton Taktile even when its limitations are taken into consideration. It could be the heart of a light-weight, portable, battery-powered rig and I’m exploring that potential right now.

Polyphonic Arduino synthesizer

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If you’re interested in building an Arduino-based ROM-pler, this next project is for you!

One of my long term dreams is to build a low-cost 60s-style combo organ. My latest project uses an Arduino UNO as a sample playback, sound synthesis engine. Although the waveforms are taken from the old VOX Continental and Farfisa Mini Compact organs, the design and code could easily use single cycle waveforms from a vintage synth, a string machine, your first born child, whatever! The 60s combo organ project is essentially a software ROM-pler that plays back up to five waveforms at a 22,050Hz sampling rate.

The project hardware consists of an Arduino UNO and a Narbotic Instruments MidiVOX shield. The MidiVOX shield has a Microchip Technologies MCP4921 12-bit digital to analog converter (DAC) and an opto-isolated MIDI input. Although the MidiVOX is no longer in production, it’s basic circuitry is easy to recreate; several other popular audio shields use the MCP4921.

Waveforms are stored in the Arduino’s program memory (PROGMEM), just like code. Program memory is non-volatile and the waveforms are ready to go just like a pre-loaded sketch. The combo organ sketch sets up TIMER1 to generate interrupts at a 22,050Hz sample playback rate. The interrupt handler reads the next sample for each of five virtual tone generators, sums the samples together, and writes the next aggregate sample to the DAC.

MIDI communication is performed through the standard Arduino MIDI library (version 4.2). The sketch registers two callback functions via the library: a note ON handler and a note OFF handler. The MIDI note handlers configure the five virtual tone generators. The sketch’s loop() function is trivial — it merely calls the MIDI library read() function and checks a reset button on the MidiVOX shield.

We all know that Direct Digital Synthesis (DDS) — the usual approach for sample playback — is a compute intensive technique for sound synthesis. DDS dynamically shifts the pitch of a stored waveform from its root pitch (the frequency of the sampled note) to the target pitch (the frequency of the MIDI note played by the musician). DDS performs waveform pitch-shifting through phase accumulation and interpolation. Floating point arithmetic is too slow and most DDS implementations use fixed point arithmetic. Even then, the computational load is heavy.

So, how did I achieve five note polyphony? Instead of storing a single waveform at a single root pitch, my approach stores twelve waveforms — one waveform for each basic pitch in the chromatic scale. The algorithm uses integer phase increments, thereby eliminating floating or fixed point arithmetic and interpolation entirely. The approach requires more space, but is quite fast. Each sampled instrument occupies 20% of program memory, allowing up to four different instruments before running out of PROGMEM.

Here are two quick MP3 demo files: a Farfisa-type sound and a and a VOX-type sound. I created the vibrato by routing the audio signal through an inexpensive Behringer UV300 vibrato pedal.

As usual, we always publish code. Need a cheap ROM-pler? Now you’ve got one!

Update 22 July 2016: If you’re into retro, be sure to check out the Arduino lo-fi beat box project. Filled with lo-fi TR-808 goodness!

MidiVOX: An appreciation and review

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They just don’t make ’em like they used to. In the case, of the Narbotic Instruments MidiVOX shield for Arduino, I really mean it!

The MidiVox is a bit of a blast from the past as Narbotic no longer manufacture and sell the MidiVOX shield kit. Major bummer. Luckily, I purchased one of these little gems from the MakerShed when the shields were available a few years ago. Narbotic kindly maintain the design information and code on their Web site.

To me, the MidiVox is a most logical combination of a MIDI IN port and a 12-bit digital-to-analog converter (DAC). The MIDI port incorporates a 6N138 optocoupler for electrical isolation and a 5-pin DIN connector. The port is connected through a “PGM/MIDI” switch to Arduino digital pin D0, also known as the serial receive (RX) pin. The PGM position connects the serial pin the usual way in order to download to the Arduino. The MIDI position connects the Arduino serial RX pin to the MIDI IN circuitry. The switch component is robust and is easily accessible when the MidiVOX is on top of the Arduino and/or other shields.

The 12-bit DAC is a Microchip Technology MCP4921. This DAC is used in several other audio shield designs including the Adafruit Wave Shield and the Nootropic Design Audio Hacker Kit. The MCP4921 connects to the Arduino SPI port through digital pins D13 (SCK), D11 (MOSI), and D9 (chip select/slave select). Conventional practice recommends using D10 as slave select (SS), but it isn’t a big deal to use D9 instead as this is mainly a software issue. Slave Select (called “chip select” in the MCP4921) chooses and enables communication with the slave device. This capability is essential when more than one device is connected to the same SPI interface as in the case of the Nootropic Audio Hacker shield.

Although it seems like a no-brainer to connect all SPI devices to the Arduino SPI pins, the Adafruit Wave Shield does not follow this approach. It connects the SD card interface to the SPI pins, but connects its MCP4921 to three ordinary digital pins. The Wave shield software bit-bangs the digital pins to transfer data to its DAC. I’m not a fan of this approach, preferring to use standard libraries instead of possibly buggy, poorly documented bit twiddling code.

The MidiVOX shield implements a 2-stage, passive filter following the DAC output. The MidiVOX sends a mono signal through an on-board trim pot into a 3.5mm audio output jack. Trim pots are usually rated for a relatively small number of operating cycles, so it’s best to set this level once and make volume adjusts at an external mixer, preamp, or whatever.

The MidiVOX shield provides a DATA LED controlled by digital pin D7. The shield also has a RESET button (momentary contact switch) connected to digital pin D6. This button is ACTIVE LOW, meaning that the button pulls D6 to ground when it is pressed. Therefore, the pin mode should be configured as INPUT_PULLUP such that D6 is pulled up internally when the button is not pressed (i.e., the momentary contact switch is open).

Construction was easy. The resistors have five color bands, but don’t let this throw you off. The construction directions give the correct color code and you can (and should!) always check resistor values with a meter before insertion and soldering. I replaced the basic header pins with “stackable headers” (two 8-pin and two 6-pin). Stackable headers provide a way to make easy external connections to the shield stack from a breadboard, etc.

The completed board is shown in the photo below. The MidiVOX is stacked on an Arduino UNO with the USB, audio and MIDI cables, and is ready to go.

MidiVox

I wrote a diagnostic sketch to check out the different parts of the MidiVOX. I wish manufacturers would provide check-out sketches instead of relying on somebody’s possibly flaky application sketch for smoke testing. If something is busted, it’s important to find it early through a directed test that isolates the failure. Fortunately, everything checked out OK the first time!

The MidiVOX diagnostic program is an Arduino sketch to check out parts of a Narbotic Instruments MidiVOX shield. Rename the “loop” functions and rebuild in order to test a particular section of the shield.

Since the MidiVOX is discontinued, we’re all out of luck if we want to get (another) one. However, I strongly recommend studying the MidiVOX design. When I first got started with Arduino and MIDI, I borrowed the MIDI IN circuitry and the low pass filter design. These are simple, solid circuits and are good basic building blocks for other designs and applications.

Where to next? My dream is to build a low-cost 60s combo organ with the era-appropriate look and sound. The organ would look like a Vox Continental with a Z-shaped chrome stand and bright red Tolex covering. It would sound like either a Farfisa or a Vox — nothing too nuanced with all of the drawbars or tabs turned on. I’d like to use a cheap and lightweight MIDI controller as the keyboard. The controller would drive a low-cost (Arduino-based?) sound generator. I’m hacking out a prototype using an Arduino UNO and the MidiVOX shield. More to come…

PERF tutorial part 3 is now on-line

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Just wrapped up Part 3 of the Linux-tools PERF tutorial.

The tutorial now consists of three parts. Part 1 covers the most basic PERF commands and shows how to find program hot-spots using software performance events. Part 2 discusses hardware performance events and performance counters, and demonstrates how to measure hardware performance events using PERF counting mode. Part 2 introduces several derived performance metrics like instructions per second (IPC) and applies these metrics to the sample application programs.

Part 3 is the newest addition to the tutorial series. It builds on parts 1 and 2, showing how to use hardware performance events and counter sampling to profile an application program. Part 3 discusses sampling period and frequency, the sampling process, overhead, statistical accuracy/confidence and other practical concerns.

I hope you find the PERF tutorial to be useful in your work! Although I produced the example data on the ARM-based Raspberry Pi, the commands and techniques will also work on x86.

PERF tutorial part 2 now available

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Part 2 of a three part tutorial about Linux-tools PERF is now available.

Part 1 of the series shows how to find hot execution spots in an application program. It demonstrates the basic PERF commands using software performance events such as CPU clock ticks and page faults.

Part 2 of the series — just released — introduces hardware performance counters and events. I show how to count hardware events with PERF and how to compute and apply a few basic derived measurements (e.g., instructions per cycle, cache miss rate) for analysis. Part 3 is in development and will show how to use sampling to profile a program and to isolate performance issues in code.

All three parts of the series use the same simple, easy to understand example: matrix multiplication. One version of the matrix multiplication program illustrates the impact of severe performance issues and what to look for in PERF measurements. The issues are mitigated in the second, improved version of the program. PERF measurements for the improved program are presented for comparison.

The test platform is the latest second generation Raspberry Pi 2 running Raspbian Wheezy 3.18.9-v7+. The Raspberry Pi 2 has a 900MHz quad-core ARM Cortex-A7 (ARMv7) processor with 1GByte of primary memory. Although the tutorial series demonstrates PERF on Cortex-A7, the same PERF commands and analytical techniques can be employed on other architectures like x86.

A special note for Raspberry Pi users. The current stable distribution of Raspbian Wheezy — 3.18.7-v7+ February 2015 — does not support PERF hardware events. Full PERF support was enabled in a later, intermediate release and full PERF support should be available in the next stable release of Raspbian Wheezy. In the meantime, Raspberry Pi 2 users may profile their programs using PERF software events as shown in Part 1 of the tutorial. First generation Raspberry Pi users are also restricted to software performance events.

Brave souls may try rpi-update to upgrade to the latest and possibly unstable release. I recommend waiting for the next stable release unless you really, really know what you are doing and are willing to chance an unstable kernel with potentially catastrophic consequences.

RPi2: Work in progress 1

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Here’s a quick status update on working with Raspberry Pi gen 2. The installed operating system is Raspbian Wheezy 3.18.7-v7+ built on 16 February 2015.

I’m happy to report that I could profile programs using PERF software events. I’m disappointed to report that PERF does not recognize any hardware (performance counter) events. This distro has Linux-tools-3.2 installed. I uninstalled 3.2 and installed 3.18 which matches the kernel:

sudo apt-get remove Linux-tools-3.2
sudo apt-get install Linux-tools-3.18

Still no joy when attempting to use hardware events. If you want to profile your program using PERF software events, please see my current PERF tutorial about finding execution hot-spots. I tried all of the commands and, with the exception of one typo, everything still works!

I’m in the process of troubleshooting my loadable kernel module for user-space performance counter events. I’ve encountered many of the same old stumbling blocks (e.g., finding the correct headers and Module.symvers file). At the present time, the kernel will attempt to load the module, then die. I cannot tell at this stage if there is a problem in the module itself or if there is a bug in Raspbian Wheezy. In case you want to dive into module development yourself, I’ve started a permanent page for building kernel modules on RPi2.

Once again, after two+ years, I want to make a public plea for more open information about the underlying hardware and for guidance and support for end-user device driver development. Quite frankly, Broadcom plays this situation too close to the chest, especially for a computer that’s advertised as a vehicle for learning and education. The dearth of information is stifling. People still struggle to identify and download essential information (e.g., Module.symvers) for device driver development. This is not true of other major Linux distros and the Raspbian folks really need to take note! Broadcom, in particular, runs the risk of killing off the goose laying the golden eggs.

Before signing off, here is a quick PERF command cheat sheet. I recommend reading the tutorial, but if you really must peck away at the keyboard… All the best!

perf help
perf list
perf stat -e cpu-clock ./program
perf record -e cpu-clock ./program
perf record -e cpu-clock,faults .program
perf report
perf report --stdio --sort comm,dso --header
perf report --stdio --dsos=program,libc-2.13.so
perf annotate --stdio --dsos=program --symbol=function
perf annotate --stdio --dsos=program --symbol=function --no-source
perf record -e cpu-clock --freq=8000 ./program
perf evlist -F

Replace “program” with the name of your application program and replace “function” with the name of a function in your program.

Second generation RPi is here

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The second generation Raspberry Pi (RPi2) is now shipping in large quantities! Given the excitement on the Web, this machine should be at least as popular as its first generation parents. Although the RPi2 model B has the same overall form factor as the first generation model B+, the designers made two substantial improvements which make the RPi2 a contender for your desktop:

  1. The single core Broadcom BCM2835 is replaced by the quad core BCM2836.
  2. Primary memory is increased to 1GByte of LPDDR2 RAM.

That’s just the face of it. Not only does the BCM2836 have four processor cores instead of one core, the cores are based on the ARMv7 architecture (Coretx-A7) including the NEON single instruction, multiple data (SIMD) instructions. The clock frequency is increased to 900MHz (from 700MHz). I’ve already begun to explore the ARMv7 micro-architecture and plan to write up a short, concise summary of its performance-related characteristics.

The BCM2836 has a different memory controller. Primary memory is no longer implemented using the Package on Package (PoP) approach. The Elpida (Micron) B8132C4PB-8D-F memory chip is mounted on the bottom of the RPi2 board (instead of the PoP piggyback).

The RPi2 sold out at Sparkfun almost immediately. Fortunately, Canakit, Element14 and Microcenter have received shipments, too. Amazon advertised the Canakit Raspberry Pi 2 Ultimate Starter Kit at a very attractive price and I immediately bought a kit. Microcenter in Cambridge had a mound of RPi2s and impatience took the best of me — I bought one. Yes, after getting the mail, I now have two.

I copied the latest Raspbian Wheezy release (16 February 2015) to a 16MByte microSD card using Win32DiskImager. The Canakit ships with NOOBS on an 8GByte card and I hope to try and report about NOOBS later. There was a little drama while bringing up Raspbian Wheezy as some relatively small, but annoying problems did crop up. Once I got past the sand traps, the new RPi2 proved to be an able performer.

Today, I copied my test software over to the RPi2. Here is a quick comparison between the older RPi model B and the new RPi2.

Platform Naïve MM Interchange MM
RPi model B gen 1 18.67 sec 6.75 sec
RPi gen 2 3.15 sec 2.42 sec

The two test cases are the naïve matrix multiplication program and the loop nest interchange matrix multiplication program. (Get the code in the source section of the web site.) Yes, that is a 6x improvement in performance for the naïve case. It’ll be fun to explore and find the reasons behind the speed-up. Fast matrix multiplication depends upon memory bandwidth and there must be some significant improvements in the memory subsystem. Naïve matrix multiplication incurs a lot of translation lookaside buffer (TLB) misses, so improvements in TLB miss handling could also contribute to the speed-up in the naïve test case.

I ditched the Epiphany Web browser as it seems to have significant bugs. The browser crashed repeatedly when loading the New York Times front page. This is unacceptable. I installed Midori, which came with the initial release of Raspbian Wheezy. The New York Times front page is a bit of a torture test. Midori loaded the page in less time than the RPi gen 1, but still felt slow and logy. I suspect that many applications will need to be compiled for ARMv7 before we end-users get the full benefit of the BCM2836. The initial result, however, is encouraging.

Well, I’ve started to reorganize the site’s menu structure in order to get ready for new content about the RPi2. I intend to retain the older articles as they remain quite relevant. More to come!

Make music with MMS on a PSR

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Yamaha Mobile Music Sequencer includes features for Motif, MOX and Tyros5, but did you know that you can create music using MMS on your PSR arranger? Yes, you can!

I’m using MMS with both the Yamaha PSR-E443 and PSR-S950 and I have written up a tutorial on making music with MMS on PSR/Tyros. This article concentrates on set-up, MIDI voice selection and MIDI file export which are aspects not covered by the MMS manual. The tutorial complements the many on-line videos that demonstrate composition and mix down. In particular, I show how to use the full 128 voice General MIDI voice set in the PSR, thereby expanding your sonic palette beyond the limited range of voices built into MMS.

Enjoy and keep on keepin’ on!

Scat voice expansion pack

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I’m pleased to release version 1 of my jazz scat voice expansion pack for Yamaha PSR-S950 and PSR-S750 arranger workstations. The expansion pack has five PSR voices which let you create “Take 6” style, a cappella arrangements and other kinds of jazz voice performances. Give the MP3 demo a try!

Four of the PSR voices are individual syllables: DOO, DOT, BOP and DOW. The DOO syllable is looped and let’s you create sustained chords for backing. The DOT, BOP and DOW syllables are short and provide scat-like expression. All four syllables are combined into a velocity-switched voice where you select and play one of the syllables based on how hard you strike the keys (i.e., MIDI note velocity). You will need to adjust touch response (and practice!) to get the most playable and musical result.

Here is a link to the expansion pack file. You need to download and UNZIP this file, then install the YEP file by following the directions in the Yamaha PSR-S950/PSR-S750 Owner’s Manual. See the section titled “Expanding Voices”.

I am also releasing the multi-samples that I used to create the expansion pack in case you would like to create a scat voice for your own synthesizer or software instrument. If you are curious about how I created the expansion pack voices and the samples, please see this blog post.

Both the scat voice expansion pack and the scat voice samples are released under a Creative Commons Attribution 4.0 International License.

Creative Commons License
ScatVoices and ScatVoice samples by Paul J. Drongowski are licensed under a Creative Commons Attribution 4.0 International License.

You are free to use the expansion pack voice or samples (even for commercial purposes) as long as you provide a link to http://sandsoftwaresound.net from your own web site AND/OR explicitly credit me in your creative work, e.g., “Scat samples/voice by Paul J. Drongowski”.