Sega Master System "Bass Mode" and More Samples

Today I've added two more things to the Sega Master System Interface - a bass mode for channel 3 and more / clearer samples.



Bass Channel
I've added what I'm calling "bass mode" for the third channel.

To understand what this means, I'll briefly explain a little bit about the SN76489 noise generator channel. Basically, the noise generator either gets its frequency either from a division of the master clock, or its clocked directly from the frequency generated by pulse channel three of the SN76489. In other words, it doesn't have its own frequency divider that is set by a data register.

The cool thing about controlling the noise channel from pulse channel 3 is that the output noise frequency is octaves lower than the current pulse three frequency. By changing the frequency of channel three whilst setting the volume of channel four (noise), low bass lines can be written.

The Sega Master System MIDI interface can be set to "bass mode" for channel three via a MIDI CC message. When receiving note data in this mode, it will write data to the frequency of channel three, yet it will control the volume of channel four. Previously, it was possible to do this with my interface, but it was a little cumbersome, having to write notes with a velocity less than 8 on channel three for the pitch, and notes with a velocity greater than 7 on channel four to set the volume of a bass line.

What the bass mode does, is it combines these actions in an easy to use fashion. It's something that I should have implemented a while ago (and I have been meaning to), because it makes things so much easier.



More / Clearer Samples
I've also added more samples to the interface, and the ones that were in there already I've made clearer. There are now twenty samples, including additional kicks and snares, cymbals, bongo and conga hits.

The samples have been made clearer by normalising to 0dB. Previously, I had been normalising to 0dB and then adding between 4.5 and 6 dB of gain, resulting in quite a bit of distortion.

I thought that treating the samples with that much gain would be acceptable - after all, when I make custom LSDJ kits, I always normalise to +6dB, when I make samples for use with Sega Mega Drive I normalise to +8dB and for Atari 2600 it was +6 dB.

It's interesting that I don't like a high-gain outcome when played through a Sega Master System - is there something different about the way that the SN76489 outputs the samples that results in a different sound? Or is it that I have certain expectations of the way that a Sega Master System should sound? I mean, when dealing with Atari 2600 there is of course a perception of low-bit depth when it comes to pitch and to some degree timbre control, so perhaps I expect a distorted result from a 2600 which I would not deem acceptable for a Sega Master System. Perhaps it is a combination of memory, perception and sound reproduction via a method that was not meant for that purpose.

Anyway, the samples sounds acceptable when normalised to 0dB but they are of course very quiet when compared to the rest of the SN76489 PSG. I have added a function whereby all velocities are divided by a third if the sample mode is enabled, thereby balancing out the relative volume levels.

I am hoping that a direct output from the VDP chip will allow for a greater signal to noise ratio for sample playback mode.



Audio Example
Listen to an audio example of what I'm talking about with all of this here.


Video Example


To be the first to know about a release date, please join the Google Announcement Group here: http://groups.google.com/group/smsm-announcements.

Sample Channel Added to Sega Master System MIDI Interface

I have started to add some form of a "sample channel" for the Sega Master System MIDI Interface. It's always a tough choice between sample clarity versus sample volume (in relation to the other channels and in relation to inherent noise).

In the video below, the audio was taken directly from the AV output of a PAL SMS Model 1 unit. I think it would have been a little clearer coming directly from the chip, however the audio output from the samples is so low that it was necessary to boost the gain by quite a bit when recording, hence there is so much noise.

My current control mapping is such that pulse channel 2 is the sample channel, and sample capability can be enabled and disabled via a CC message. If sample mode is enabled on channel 2, then a note-on will trigger a sample and a note-off will stop sample playback.

To be the first to know about a release date, please join the Google Announcement Group here: http://groups.google.com/group/smsm-announcements.

little-scale Featured on Free Music Archive

It is very much an honour to be featured on Peter Swimm's chipmusic blog, written as a guest curator at the Free Music Archive. Read the blog entry here.

Sega Comparisons

I've made recordings of a number of Sega Mega Drive-compatible consoles playing back the same music. The audio below has been normalised.

A. Sega Mega Drive 1 (output via headphone socket):
http://milkcrate.com.au/_other/comparisons/sega_2/MD1%20Head%20Phone.mp3

B. Sega Mega Drive 2 (output via AV socket):
http://milkcrate.com.au/_other/comparisons/sega_2/MD2%20AV.mp3

C. Sega Genesis 2 (output via AV socket):
http://milkcrate.com.au/_other/comparisons/sega_2/GEN2%20AV.mp3

D. Sega Mega Drive 2 with CCAM Mod (output via additional RCA sockets):
http://milkcrate.com.au/_other/comparisons/sega_2/MD2%20CCAM.mp3

E. Sega Nomad (output via headphone socket):
http://milkcrate.com.au/_other/comparisons/sega_2/Nomad%20Head%20Phone.mp3


My favourites are A and D, but I think for live shows D is a better option because of the form factor of a MD2 compared to the bulky MD1.

Sound Bytes 4 Footage

Performance-worthy Sega Mega Drive 2

I've installed TmEE's Genesis 2 Crystal Clear Audio Mod, and I have to say I am very happy with the outcome. Sounds awesome! Thanks Tiido!

I can highly recommend this mod to anyone thinking of making music with a Genesis / Mega Drive 2.

The mod was much easier to install than I thought, TmEE has made some very clear instructions, and even the parts that I thought might be hard (removing the caps from the original board, removing SMD resistors) were actually very easy.

Now for a very quick audio example: Before / After.

God In Pants Underclock Mod

I thought I would share some of the work that Chris Guy (aka God in Pants) has been doing. He recently modified his Game Boy with a 2MHz switchable crystal.

The interesting thing is that he found a switch that fits nicely in the (I suppose) rarely used DC input jack hole in the GB chassis. I like it!

Pictures from Sound Bytes 4

talkshow boy

astro zombies

celsius

doctor dollar dollar

little-scale and the real trippy-h



little-scale

Buildings in Melbourne, Victoria

Big News: New Tree Wave Release!!

http://treewave.com/10inch/

Retuning an Underclocked Game Boy

The Problem
There is a modification to an original Game Boy that involves replacing the internal crystal oscillator with one of a different value, documented by the genius Gieskes. Often, a value of 2MHz is used to replace the default value of 4.194304 MHz because 2MHz crystals are easy to find in shops and on the internet, or at least thats what I do.

However, this creates a problem, in the sense that the crystal oscillator is responsible for controlling all timing aspects of the Game Boy including the frequency pitches of the pulse oscillators.

As a result, the underclocked Game Boy plays back just under an octave lower than its unmodified counterpart. This tuning difference is annoying and means that its not very satisfying to use an underclocked Game Boy at the same time as a normal Game Boy or any other instrument.


The Solution
The idea for a solution to this problem comes form Tom Gilmore aka 10k.

The easiest way to remedy this problem is to simply replace the tuning table inside of LSDJ with a newly created tuning table that uses 4Mhz as a master clock source (which is 2 * 2MHz) instead of 4.194304 MHz. As a result, a C3 will play back on the unmodified Game Boy as a C2, instead of some disgustingly out of tune B or something similar.

Open up the LSDJ ROM in a hex editor. I use Hex Fiend for OS X. Find the tuning table in the LSDJ, which starts just after location $6D30 with the bytes 2C 00 9C 00 06 01 etc. Select
216 bytes starting with 2C and 00.

Now, paste the following 216 bytes over that area of memory:

8900
F400
5901
B901
1302
6802
B902
0403
4C03
9003
CF03
0C04
4404
7A04
AD04
DC04
0A05
3405
5C05
8205
A605
C805
E805
0606
2206
3D06
5606
6E06
8506
9A06
AE06
C106
D306
E406
F406
0307
1107
1F07
2B07
3707
4207
4D07
5707
6107
6A07
7207
7A07
8107
8907
8F07
9607
9C07
A107
A707
AC07
B007
B507
B907
BD07
C107
C407
C807
CB07
CE07
D107
D307
D607
D807
DA07
DC07
DE07
E007
E207
E407
E507
E707
E807
EA07
EB07
EC07
ED07
EE07
EF07
F007
F107
F207
F307
F307
F407
F507
F507
F607
F707
F707
F807
F807
F907
F907
F907
FA07
FA07
FA07
FB07
FB07
FB07
FC07
FC07
FC07

Save your ROM file, flash it onto a cart and then pop it into your underclocked GB. Enjoy! You can sync your normal Game Boy as slave from your underclocked Game Boy as master.


Demo Video

Sound Bytes 4 Photos on Jump Button

See more pictures at full resolution here.

Atari 2600 Percussive Creative Commons Sample Pack

This Sample Pack by Sebastian Tomczak is licensed under a Creative Commons Attribution-Noncommercial 3.0 Unported License. More information about this license can be viewed here: http://creativecommons.org/licenses/by-nc/3.0/

This sample pack features 28 short percussive samples recorded from an Atari 260 Jr PAL console. Previously, people have requested dry, direct recordings of these samples as a pack - this is why the pack is being posted.

Download it here.

Sega Mega Drive / Genesis PCM Demo Video

A video which is a follow on from this.

Bleep Bloop Game Boy USB Cart!

PCM Support Added to Sega Mega Drive / Genesis MIDI Interface

Sample playback of some sort seems to be a popular request for the Mega Drive stuff, and some people have said that it requires something, if only some basic drum sounds. So, I have added basic support for PCM sample playback - specifically percussive and drum sounds - for my Sega Mega Drive MIDI Interface.

Currently, the mapping is as follows. MIDI channel 6 can be put into a "DAC Mode", after which the following notes (that wrap around every two octaves) will trigger the following samples:

01. C-1 - kick 1
02. C#1 - snare 1
03. D-1 - hat closed 1
04. D#1 - hat open 1
05. E-1 - tom low 1
06. F-1 - tom hi 1
07. F#1 - cow bell
08. G-1 - kick 2
09. G#1 - snare 2
10. A-1 - hat closed 2
11. A#1 - hat open 1
12. B-1 - tom low 1
13. C-2 - tom hi 1
14. C#2 - ride 1
15. D-2 - crash
16. D#2 - kick 3
17. E-2 - snare 3
18. F-2 - ride 2

A note-on will trigger sample playback. A note-off will stop sample playback. Furthermore, using MIDI CC changes the sample playback speed / pitch.

Stay tuned for a demo video.

K808 and Dot.AY on 4ZZZZ (with little-scale interview)

Alex Yabsley aka Dot.AY says:
"On 14th of June 2009, I was lucky enough to be asked to guest program a slot at Brisbane Community radio station 4ZzZ. It turned out basically being myself programming an hour and a half of my favourite Chip music and talking in between with the host K808. There is also a featured pre-record interview with Little-Scale that was recorded in Adelaide earlier this year."

(Read more and download the audio here)

SB4 Set Times Update

The Sound Bytes 4 line up for tomorrow has changed:

Dr Dollar Dollar (AKA Cool Thomas) until 8:15 and throughout the night
Able Archer 8:15 - 8:45
Talkshow Boy 9:00 - 9:30
Astro Zombies 9:45 - 10:15
little-scale 10:30 - 11:00
Derris-Kharlan 11:15 - 11:45
Maddest Kings Alive 12:00 - 12:30
10K Free Men and Their Families 12:35 - 12:55
doy.AY - 12:55 - 1:25

Error Repeat as Physical CD + Free Fridge Magnet

I have made a number of copies of Error Repeat for the upcoming Sound Bytes show in Melbourne tomorrow. Each copy comes with a free little-scale fridge magnet! If anyone wants one, please contact me - though you will have to be very quick as stock is strictly limited. The price is US$10 including worldwide shipping.

A VERSUS B

http://8bitcollective.com/music/little-scale/A+VERSUS+B/

http://8bitcollective.com/music/Jonnyriddle/B+VERSUS+A+(little+scale+Freudian+Remix)/

http://8bitcollective.com/music/PlainFlavored/A+VERSUS+B+(Man+and+His+Interpretation+of+Symbols+Against+Himself)/

http://8bitcollective.com/music/Subway+Sonicbeat/Arp+VERSUS+B/

http://8bitcollective.com/music/Derris-Kharlan/Accapella+vs+B/

MIDI to QBASIC Converter

So I started working on a little patch that takes real-time monophonic MIDI data and outputs a .BAS file that is compatible with QBASIC. Currently, it makes use of the PLAY command, and generates rhythm, octave and pitch data as well as converting MIDI CC 1 to the MUSIC TYPE parameter (MUSIC NORMAL, MUSIC STACCATO and MUSIC LEGATO).

little-scale: Dynasty Released on PAUSE (II) Music

Dynasty is now out on the II Music label. This is a re-mastered version, and is available as both lossy and lossless audio. Get it here.

Meningie in Winter

Sega SN76489 in MD2 vs SMS2

The Sega Mega Drive 2 implementation of the SN76489 PSG displays some interesting sonic characteristics, when compared to a Sega Master System or Sega Master System 2.

To my ears, there is some sort of timbral change associated with volume change, especially if only one channel is playing. I have no idea what is the cause of this phenomenon, but it sounds to me like it might be something to do with a DAC portion of the VDP or some sort of quantisation or aliasing effect. If anyone knows why this exists, I would love to learn about it.

Let's have a look at some waveforms from the two audio outputs.

The Sega Master System 2 output, taken directly from the chip.

The Sega Mega Drive 2 output, taken from the AV output port.

The difference is quite striking, and can be clearly heard in the following examples:
- Sega Mega Drive 2 fade in and out (as a .wav file)
- Sega Master System 2 fade in and out (as a .wav file)
- Sega Mega Drive 2 fade in and out with a musical example
- Sega Master System 2 fade in and out with a musical example

Sega Mega Drive Compatible with Sega Master System MIDI Interface

I am happy to report that my Sega Master System Interface is compatible with the Sega Mega Drive with a Power Base Converter or similar device.

Basically, the Sega Mega Drive / Genesis are backwards compatible with the Sega Master System carts, but require a device that sits between the console and the 8-bit cart.

In the above picture, you can see the converter that I use, which is a very affordable Tototek model.

Join the SMSM Google Announcement Group to be notified of when this interface will be available.

SN76489 Support for Sega Mega Drive MIDI Interface

Finally, I've had a chance to add support for the SN76489 PSG chip in the Sega Mega Drive for my MIDI interface. The thing I love about the Mega Drive is the FM sound (which is why I've been concentrating on that), but of course everyone wants access to the PSG as well. The SN76489 support is basically a port from my Sega Master System MIDI interface, and includes many (but not all) of the latter's functions and features. Currently the MIDI channel mapping is as follows:

1 - YM2612 FM channel 1
2 - YM2612 FM channel 2
3 - YM2612 FM channel 3
4 - YM2612 FM channel 4
5 - YM2612 FM channel 5
6 - YM2612 FM channel 6
7 - SN76489 PSG PU1
8 - SN76489 PSG PU2
9 - SN76489 PSG PU3
10 - SN76489 PSG NOI

As I often say with these sorts of updates, join the Gen/MDM Google Announcements Group to be notified of when this device will be available.

Sega Nomad MIDI Interface

I thought I would mention that my Sega Mega Drive / Genesis MIDI interface is now compatible with the Sega Nomad. Demo video here. As I often say with these sorts of updates, join the Gen/MDM Google Announcements Group to be notified of when this device will be available.

Video of Waveform Permutations

This is a video of my hardware-based waveform permutations.

TmEE Genesis 2 Crystal Clear Audio Mod v1.0

The hand-built board by TmEE for his Sega Mega Drive 2/ Genesis 2 Crystal Clear Audio Modification v1.0 arrived in the mail. I don't think that I will have a chance to install this before Melbourne, but we will have to wait and see. So, what's this mod all about?

TmEE says:

"This will make your MD2 or other ASIC based (5487, 5660 or 5700) setup like Nomad, Wondermega, Xeye etc. really singing then, putting all other setups into shame unless they're modded also. Only real difference compared with older versions of this is that the output is much more louder now (abuot as much as MCD RCA outputs, which is sufficient enough) and long cables will not attenuate high freqs anymore All the signal sources (32X, MCD, YM, PSG) are mixed together at correct levels, referenced by a MD1 withuot TMSS (aka the good sounding models in unmodded state)."

Sega Nomad

A Sega Nomad arrived in the mail. The screen looks better than I had imagined.

Hardware-based Waveform Permutations

I've made a simple circuit that will generate all possible waveforms that have four bits of amplitude and are four samples long. It's very simple, and follows the same concept as my previous forays into this concept (which were all software based).

Basically, there is a counter that is 16 bits long, and is pulsed by a continuous square wave. This controls the speed of waveform change of the output waveform. Every four bits of the counter are fed into a multiplexer. There is a multiplexer for each bit of the output waveform, and so every first bit out of four from the counter is fed into multiplexer 1, every second bit out of four from the counter is fed into multiplexer two and so on up to multiplexer 4.

The output of the four multiplexers is chosen by a separate binary counter, which is clocked by an independent square wave. This controls the frequency of the output waveform. Thus, the output of the combined four multiplexers essentially "steps through" the waveform, and is then converted into an analog voltage using an R2R DAC.

If that wasn't very clear, I've prepared a simplified diagram:


Schematic:


Circuit Breadboard:

Universal Programmer

I picked up another programmer in order to be able to program (M)27(C)32(A) and 16 bit devices.

More Atari 2600 Samples in Action

http://8bitcollective.com/music/little-scale/Chermside+(Atari+2600)/

Images from ACMC2009

The Blue Elephant (soundtrack by Poppi Doser)

Posters

My poster

Peter McIlwain and Ross Bencina jamming with Nodal and AudioMulch.

Paul Doornbusch presents a two hour lecture on the history of electronic and computer music over the last 100 years.

Christian Haines presents his paper on mobile phone-based group performance.

More Atari 2600 Samples

I've added some more samples to my Atari 2600 interface. The MIDI mapping is as follows:

F3 - kick
F#3 - snare
G3 - rim
G#3 - tom
A3 - hi-hat closed
A#3 - hi-hat open
B3 - ride cymbal
C4 - crash
C#4 - pock
D4 - toom
D#4 - dom1
E4 - dom2
F4 - pom
F#4 - ick
G4 - zick
G#4 - zilch
A4 - electro kick
A#4 - electro snare
B4 - cowbell
C5 - circuit bent toy guitar
C#5 - SP0256-AL2 allophone "AA"
D5 - SP0256-AL2 allophone "AX"
D#5 - SP0256-AL2 allophone "DD2"
E5 - SP0256-AL2 allophone "EH"
F5 - SP0256-AL2 allophone "NN2"
F#5 - SP0256-AL2 allophone "OW"
G5 - SP0256-AL2 allophone "OY"
G#5 - SP0256-AL2 allophone "ZZ"
A5 - A chord from Debussy's "La Cathedrale Engloutie"

8BC Nightstalker Compilation

I've got a track on this one for Sega Mega Drive and NES.
Download it here.