Theo Verelst Local Diary Page 32
The same holds as for my tripod and
other diary pages: nothing on this page may be copied or changed and
distributed except that the page as a whole may be printed or otherwise
transferred in unchanged form, mentioning the original URL
and global page reference, and that holds for everyone on the globe
and beyond, including so called 'christians' and self-appointed 'Secret
Thu 23 22:10, 2006
Well, a lot more diary pages lately, measured by averaging
per month of so. I thought I'd write some more about interesting
subject, at the risk that I compensate with interest in myself for the
lack of interest from many others which would be reasonable.
The server did more work already in february than in the previous 3
months, but a quarter of the hits is my own, because of the cgi script
mentioned on the previous diary page.
|Summary by Month
Great work: the Yamaha S90 was crafted with a Digital
I had the spirit last sunday (march 12, the date above is the start
date of the page being written) to open up a years old S90 sound
synthesizer which is (in a newer version ?) probably the or amoung the
top selling synthesizers of the last years, and figured out wether I
would be able to tap the signal going to the main output DA converter
and figure out the digital format, so as to use the digital synthesizer
internal signal for my own purposes, for instance to be able to record
music from it without having the AD convert the (analog) synthesizer
sound output to get it in a computer or other digital machines.
I had not too much trouble guessing what the various electronics in
this high tech machine would have to do in the output section, though
some chips were not main stream, and the DA converter chips (up to 96
kHz, 24 bit) I had to look up on a japanese server, but luckily they
had (english!) free datasheets available, so I could figure out the pin
connections, the internals, and also the signal formats to drive these
digital to analog converters.
Don't get me wrong: this HIGHLY specialistic electronics work as in
that your average computer hardware guy wouldn't even know where to
begin, and your TV repairman wouldn't either, I'm quite sure... So this
is a theover game when he wants to do something a bit more exiting than
some average electronics making, and as we know theo is an (official)
university level electrical engineer wit a lot of electronics
experience. So this is a hobby project, but not for starters, you
shouldn't try this at home unless you really know what you're doing!
Breaking a synth like this is not funny, so this project had to be done
with great care, because all those digital chips and electronics on the
board of the synth included soldering wires to essential signal lines,
tapping internal supplies, and getting (live, though of course very low
voltage) signals to the outside of the enclosure, while some of the
wires being tapped could already break to attached chips by static
voltages from me wearing a static sweater or so when only touched by a
So I had to ground myself and the machine and work very carefully, I
included resistors in the signal lines coming out to prevent accidental
shortcircuiting of the outputs of important signal processing chips in
the machine, and I made a stabelized supply and a buffer chip in
between the outputs to make the flatcable which I slid through an
extension slot lid in the back at its external connection relatively
safe, and included resistors to make it even shortcircuit-current safe
to use in like I have now first tried on a breadboard, to connect it
over a voltage divider to a Xilinx FPGA demo board, which to my
pleasure has now been used to extract the correct bits from the
outcoming bitstream to reconstruct the 20 bit stereo sound samples
produced by pressing keys on the keyboard of the synth.
To check wether those samples are indeed sensible and error free the
signals as are also fed to the internal DA converter, I connected a
self made fast 8 bit DA converter to other pins of the FPGA board, and
fed it with the most significant 8 bits of the 20 output bits of one
digital audio channel, which, after changing also the two complements
representation into a positive number one, indeed makes that DA
converter output sound like the pianos and other sounds from the
Great, isn't it!
So now I have studied S/PDIF a bit, I think I know the protocol, and I
happened to have optical transmitters and receivers lying around from
Conrad for normal optical link connections, and looked at an open
source spdif fpga implementation to make this project into a spdif
output for a S90 synthesizer. Yep, thats right. Should be cool.
Insanity? Nope, the digital signal is already there, and works fine,
and without glitches or doing something wrong with the synthesizer
(like heating up chips because of wire loading the outputs).
Here's a picture of what is working thus far, without any damage
to the synth, its kept functions throughout the whole operation, which
mainly makes use of some clear soldering points and 4 test point
connections on the leftmost synth board, which are very small, though:
The synth mod/extension
with a 7805 chip and a 74hc14 schmitt trigger to buffer all output
The signal is a 64 bit frame length, 2 subframe (stereo) of 32 bits
each msb first, lsb left aligned 20 bits effective , 44.1 kHz frame
rate bit stream, where the word clock ( left/right state change at the
beginning of each subframe) is available and the bit clock is 2.844 and
then something MegaHerz. Then I have two buffered signals for the main
out and the assignable output, so 4 20 bit signals at CD rate.
For people interested it seems the DA converter chip is probably
running in mode 4. I'll have to carefully measure someof its pins to
find out wether it has a emphasis on the signal on. I improvised a
frequency counter in the the fpga (the demo board form the xilinx page) to give me 4
digits on its display indicating frequencies of signals on one of its
input pins in kiloherz, which soon gave me the word and bit clock
speeds which showed up nicely and immedeately when the synth is
Remember, unless you want to risk unrepairably blowing up your (or the
owners) S90 synth, DON'T TRY THIS YOURSELF, unless you really
understand what you're doing and know how to work anti-static. I'll
make the fpga programming project available as open source, probable
when I have the SPDIF working, which is not yet...
Sketch diagrams of the buffer
circuit and the fpga board number connections:
The 12 volts is taken from the synth boards 7805 input pin, and the
ground from a big capacitor nearby. The word and bitclock are taken
from the assignable output DA nearby test connection pads, which I
corrected after I took the picture of the board from above, liek I
indicated, and the main output DA has one test point: the digital data
As I said: the signals are gitchless stable and can be read well by the
fpga and the interpretation after deserializing thus far seems
completely correct as a two complement binary digital signal of 20 bits.
These are dumps from the FPGA "program" schematic diagrams to drive the
self made DA converter (8 bits) to test the circuit and the decoder of
the data which takes the information from the synthesizer internal
circuit board and buffers it to be fed to the external FPGA. First, the
block diagram with the as yet three signals (1 bit) in, and the byte
out to the DA converter connected to external pins of the FPGA:
This is the actual test circuit:
The serial data comes in from the left top, and is shifted for 4x8=32
bits where 4 stages of shift registers are feeding eachother from the
most significant bit, then from the word which has been formed at the
transition moment of the word clock, the relevant 20 bits are taken,
and converted from two's complement into linear positive offset codes,
of which the highest 8 bits are connected to the DA converter.
Of course I'm now working on a matching SPDIF (optical) link converter
which fits this output, that should even be a nice product.
How early was telecomunication happening after royal mail
with seal, horses over roman roads, and smoke and fire symbols?
Well, we all know Morse code and the Telegraph already exist a long
time, and telephone existed in the early 1900s, but for instance what
happened between Europe and the US?
In fact in EIGHTEEN hundred 60 there was already a telegraph connection!
But an automated phone connection had to wait until the 1960s.
Lots of transmission line properties and heavy science are in that
field, including the ampification along the thousands of kilometers of
wire, without accumulating a lot of noise. Currently I'm sure the same
holds for internet lines: how much bandwidth would there be in total ?
Most of the internet cross atlanctic traffic used a cable I conclude
because ping times are too short for normal satellite connections.
There also was the automated telegraph: the telex, which in the
beginning of the 20th century was centered around London and spun most
of the world.
In fact probably the most interesting line was the line Marconi has
pioneered: the wireless transmission across the atlantic! That was a
major branch of electronics sports in the early 1900s. Hundreds of
kilowatts of transmission power and very big and long antennas to get
messages around to europe. Thats something else than wireless phones or
Just a word
I read in a Sound On Sound magazine article on the web that analog
synthesizers were though to sound splodgy,
which is a great word I think.
An irregularly shaped spot, stain, or colored
or discolored area: "spectacular splotches of color and beauty
in the blossoms" Wendy Lyon
Ha ha, funny. Splodge.
An interesting dutch word which I cannot just form the top of my head
translate is: "Schallen" Consider it a homework assignment and mail me
the answer.. ("blare" ?)
The imperialist IT motherf*s
All of them ? No. I'm sure many "real" programmers and
Li/Unix users aren't that way anyway. But I think the software beast is
all too real, especially in Europe, which messes up more than can be
tolerated by reasonably sensitive human beings.
The crudity, the raw lust for power and even control, the ruthless
Gestalt thinking without humanity, mercy, grace, space, respect,
sensitivity, professional ethics (much), and, the hardest word of all:
δημοκρατία (demokratia), δημος
(demos) the common people
+ κρατειν (kratein) to rule
the suffix ία (ia), literally "the common people rule") is a system
where the population of a society
controls the government
. It may be narrowly defined as that
government specifically, or more
broadly to describe a society as a whole, which can also exert political power
and social power
Just as a recent finding on the wikipedia, this is from the 1917
Because the copyright expired, it appears to be free on the internet,
I've scaled and processed the next a bit:
Would it be because of the army EE nature of the early beginnings that
thpse concepts didn't exactly make it in the IT world?
The Eniac Vacuum Tube
computer built in the 40s (!)
No, I don't think so.
I guess in the time of the 5th (6th ?) generation databases and
Artificial Intelligence, talking robots, and not to forget (though I
rather would immedeately) adventure and role games it would be a good
challenge and nursery level education for computers and their users to
learn such concept and get their brains and processing cores around
that concept. And proof in tests that the lesson has been learned, or
I'd have to believe that their IQ is not sufficient, or persons want to
be bad. Ough, that would have to be noted as a criminal organisation.
A world wide one. Brr, spooky. Maybe the international socialists must
then take over. Nationalistic socialism has proven a bad idea.
Most IT are quite unaware of the real powers behind their little gross
beast, to begin with: the computer makes of the first hour, the writers
of the Operating Systems and their parts which are copied into all
"new" things, except seldom intelligently, and most of all: the
computers themselves, the hardware, the processor and its microprogram
which are all made by only one singular party: Electrical Engineers.
Recently I voted for the ACM SIGGRAPH new director, for which a paper
(snail mail) card was sent with information to vote on voting-site. To
keep the jesuits from taking things over at siggraph, I voted for Sue
Gollifer as new director, which should normally be ok: a woman art
person is probably an ol angle for a change event though the conference
is more technology and especially science oriented.
Well, hopefully the new democracy of the protestant kind is working...
Self-making High Quality Computer Graphics
Well, it's done on a supermarket-bought machine with only
Free Software, in this case Cygwin, which is great to compile
professional programs outside of Linux on a windows machine.
I've looked a bit at this (good) book:
And for instance downloaded and compiled the following basic texture
The program can be compiled with cygwin (on a windows machine) and run:
Resizing the window works, then the pattern doesn't interfere so
clearly with the dot pitch:
The above is a simple texture demonstration where two three-dimensional
polygons (not flat but in 3D world) are seen through a virtual camera
with a checker pattern made on them. On the other side of the
ocmplexity spectrum, the following is a (not self compiled) demo of a
pond with grass around it, which is real time with moving water waiving
grass and moving clouds. Click on the image for a larger version with
Click on this link for a mpeg4 movie
which plays in the quicktime movie player, or on the next image to play
a regular (but much bigger) mpeg-2 movie:
The scene can be rendered in real time with a NVidia 6700 card, which
in such event turns a bit hotter (up to 70 degrees or so), and has an
incredible number of polygons of 150,000 for all the moving grass
pieces which still is rendered up to 30 frames per second in almost
high definition resolution. There were high priced top workstations in
the past which could only dream of such quality.
I made the movies in real time using a hardware mpeg-2 encoder which
reads from the tv-output, which isn't optimal, but not bad either, and
gives a fair impression of the result in a short time.
The next example of OpenGL 3D graphics is the following sphere which is
adapted from a opengl example from the web (check opengl.org) which can
from source code be compiled on windows using VC or Cygwin (prefered by
me, VC appears to not work good). I've added a image save routine which
writes an animation frame in compressed jpeg form to disk for each step
in the animated sphere rotation. Thats great to make animations of 3D
scenes, and I used ffmpeg to create movie files from autotmatically
generated stills in mp4 and mpeg(2) format, in this case both can over
a fast dsl line be viewed without waiting, the mp4 quality (for
instance viewable with the free quicktime movie viewer) is better.
Click on the images to see the movies:
A little adaptation to the graphics program made the sphere into a
In all these renderings, note the smooth highlight on the ball, which
is a reflection of the virtual light source, and is also rendered in
real time, including the jpeg saving (which is first preceeded by a raw
image save in ppm form, taking some disk bandwidth), because it is made
with the hardware shader from the graphics card, driven by a Cg
program. Interesting new possibilities.
A non-shader OpenGL example is billiardgl, which is opensource, but I
couldn't easily compile it on Fedora Core 4, so this a dump from the
windows pre-compiled (free!) version:
Looks great, and plays good, too.
A real piece de la resistance is the windjammer demo from NVidia which
also runs in realtime (at least 25fps at 1200x1600 resolution) on the
6700 card, see the movie below, click on the screendump to download
mpeg format movie, with sound effects I added:
The screen dump shows a Linux mplayer running over a network to a
windows X server, taking about 90 percent of a 100BaseT ethernet
bandwidth, but works. Here is a mp4
version of the same movie, which loads realtime from the server
provided you have enough download bandwidth and not everybody tries at
the same time... To start viewing immedeately, copy the link and paste
it in the Open Url of the viewer you're using, mostly that gives you
immedeate picture while downloading, possibly after pushing play after
a little bit has downloaded.
What are we planning here, Verelst?
As most readers will know, I've made various audio
amplifiers and of course many people have looked at HiFi equipment and
folders. Back in the end of the 70s I was into HiFi as a concept
because I had well read my library books, Philips magazines,
electronics store catalogs (Contact in the Hague, Tandy later on) and
HiFi flyers and folders.
HiFi was like a holy grail. Not like people or religion, but for music.
Absolute spitzenklasse was out of financial reach possibly for half a
lifetime, but a good obere mittelspitzenklasse or so was a good target
for dreaming about or so, in the field of audio. So I had my
interesting radio, one of the first Philips cassette recorders, with
seperate microphone, a stereo tube amplifier with sony speakers, an old
tape recorder, a pick up, and a connection to the stereo in the living
room when I was 11 and started making my own mixers. At first mono
devices in a large cigar box, later I made my own wooden mixer
enclosures, which I liked to design to look and work good and which
held more and more electronics the next years.
I found this poster in delft, the mixer drawing looks like they found
my old notes from when I was a kid and used them, disgusting.
Anyhow I at some point made a working and good sounding powered mixer
and then I had a reasonable cassette deck, converted a car radio to a
tuner and made my decades lasting stereo 4 channel good quality mixer
in a neat wooden enclosure. I made good recordings from my tuner and
started to work on better and more powerfull amplifier such a s a good
sounding 2x10W tip31/32 based end amp, even with stabelized supply and
I tried some powerup amps and ways to make them work with good
frequency range and stable,too. Finally when I guess I was 15 I made
myself a speaker set with quite good Philips 10" woofers and middle top
range tweeters, which were large pressure enclosure with very good
damping and thick wood and to drive those up to real loud sound levels,
I built with adaptations a 2x75 Watt (!) RMS end amplifier from a book
example, which served as my main amp for years, and was able to at
school a;so blast nearly the soft tiles from the ceiling when really
put to the test... I could use an oscilloscope at home, which showed
that the clipping point really corresponded with an actual 75 W RMS per
channel, which especially in 1980 or so was really really loud.
At the time I was in the school technical commitee, which I later led
for years, which was about loud band amplification, with only an 80
watt amp, but at home and with friends I was into good quality, from
source to speaker a good frequency response, phase linearity, low
distortion, low noise, low wow and flutten for tapes and rumble for the
turntable, more those propeties than raw power. When I at 18 had some
synthesizers and a home studio (teac tascam 244) to use, I still was
also as musician more into high quality sounds than what many
guitarists for instance are into: more sound.
I didn't have the powers to achieve supreme sound walhalla, but an
expensive headphone on a good preamp an recordplayer got pretty far,
and I sure didn't have modest means, like I wrote, and of course I
listened to sometimes expensive enough stereo sets from friends or even
at Hifi stores, and a bit later I had a very good spec Phillips
amplifier and Jamo 504 (I think) monitors for the home studio, which
with the first and a half generation of CD players sounded pretty good,
and also recordings form the only Phillips 3 head cassette deck I had
worked for sounded pretty good. I lacked a nic big sub-woofer for the
lowest notes, though I had experimented with old radio speakers I had,
of which one big one I put on top of a wooden blanket crate, which was
the best low I'd had ever, but not up to 70 watts of power...
This picture I processed from a setup at a big concert, where a bunch
of Crown amplifiers are used to fill a big hall with a love performance:
Some of those type of amplifiers (each single 19 inch rack unit) can
drive speakers with a few kilowatts of real output power, where they
even reuse energy to keep the speakers under control to prevent
excessive heating up of the case, which for 'normal' purposes is a low
of power, especially if its real and continuous. The crowns are well
known and of reasonably quality, certainly for the power and power
effectiveness they offer, and appear to have a switching output design,
which is like a special Class-D type of design, also costing less
heating of the amps. Distortion is not so good for HiFi norms,
depending on the model, and I'm not sure what the damping at higher
frequencies is like, so this is a compromise for making a stadion
filled with loud sound, which isn't too bad.
On the consumer side of things, this is a current Conrad offering: a
HiFi amplifier with pre-amp and remote control, and a nice display:
The screws on the side and a few details 'spoil' the super high end
look, and indeed it isn't super high end quality we're talking about,
but it's interesting just the same, the specs aren't bad:
About 10 times more distortion and 10 times more noise then my recent
end-amp (which the mos chips) (...), and less than half the power, but
not too bad, and it includes a pre-amp.
It's almost orthogonal
(--> "tangent" , nodge nodge, know what I mean) with the design
traks of my latest self made end amp, which is relatively few parts
(power-chip based), no pre-amp, though I use a measurent-type opamp
preamp from the synth enclosure, which is very un-dressed up, no input
switch, even, DC coupled output, very low noise, very low distortion
(the pre-amp even extremely), which is also by absence of electronic
(also digital) volume and tone controls, which usually generate rather
horrific distortion by products, and the case is heavy duty enough:
black metal 19 inch, metal frontplate, it sat under all kinds of
luggage in the back of several cars, even to france and back, and
performed without a glitch.
Here we have a lot of elecronics parts, inputs, electronic and
digitally controlled volume and tone controls:
and a discrete component end amp:
with elcos in the signal path, and a relais (for switch on delay or
short circuit/DC offset protection ?), a discrete (!) stabelized
pre-amp supply, a plastic enclosure (from the looks of it) with fragile
display and "modern" knobs, which I rarely like better, though. And it
costs only 80 euros, remote included.
Would this all be like in this rather expert level book:
Well, parts of it, I'm sure. I enjoyed making amplifiers in the
beginning of highschool, and I must have made all kinds by now: I
started with a tube amp and some tube radios, then I started building
basic push-pull and comarible ones with parts I could get my hands on,
2n3055's were expensive on allowance at age 12, but I had those, and
2n2901s from radio shack iirc, I had good results with chip amplifers
back then: good quality, nice sound, though oscillation control was an
issue with one of them, and power only up to 2x6 Watt. Then I built a
tip32/33 (or 31?) based amp from a book which was 2x 10 Watt RMS, which
was in fact a real breaktrough: good power (10 real watts in my small
room was loud!) and also good quality for the time and good
high-response, those tips aren't sluggish. Then the 75 Watt beast of
pleasure, that was great, I used that with pleasure for many purposes
for years, when I read about in the library book under the blankets
(when I had to sleep) I hadn't dreamt much of actually making it and
using it a number of years later. I also made headphone amps, and more
recently I experimented with (self designed) power FET end amp stages
with tranformerless voltage multipliers (for 12 V supply) and
even with switched designs. And then of course I saw the 100Watt Fet
Chip Amp at Conrad Rotterdam (now gone) and bought more than a few to
built in, and even sell the result.
I knew that the place where the ground is attached and where the
feedback lines are soldered matters for quality, really, it does, see
the section from the below as an example, which could be measured like
A difference measurement with a linear transformed version of the imput
signal and mixed with the end amp output signal in the right ratio to
end up with the added distortion products.
The above also speaks about grounding of the pre amp and the end amp,
which is also an issue with the power opamps I used recently: a
soldering point a few centimeters away can make a difference, for
instance in hum or feedback accuracy, see above. Imagine making a
potent 100W RMS (300 Watt peak per channel) and very wide frequency
range MOSFET amplifier oscillate supersonic without noticing, that
could fry some perfectly good tweeters, so I've been quite on the alert
to prevent that, used short feedback wires and loops, carefull with
parasitic PCB capacitances which could include small poles in the
feedback lines, etc.
And especially: use the right grounding points: 10 amps per channel
through ANY normal wire is bound to creat voltage differences, even
over 10 cm of wire which can easily be amplified and lead to (audible!)
distortion and even instability. It really can, I found out with my
first powered mixer with mic input. It's called 'motorboating' and it
wasn't a funny result of all my work. But after having redone most the
soldering and a lot of shielding, I got that machine to work at the
A great enhancement to audio amplification is whats oftn called
Surround Sound, or reverberation.I programmed a dual core DSP to
generate that effect, and to work around the same problems that plague
end amplifiers with switched supplies I gave the DSP + analog circuitry
board a torroid transformer instead, which a conventional stabalizer
It gets pretty hot at 1 amp because the smallest tranformers are 12
volts while I only need 8+ the ripple and the chip voltage drop. "There
must be some kind of way out of here"
On the driving side the below shows a digital volume contol which is up to standard, this high grade
version chip could possibly even be used for a SSL mixer console
quality level, in this case it is driven by a FPGA which is serially
linked to a linux PC.
The pcb with the leds normally contained a ARM7 microcontroller which
reads a potmeter and drives the stereo voume control chip from TI, the
microcontroller has been lifted from its socket and 3 test wires from a
self made connector to the fpga prototying board are slid in the 1/10"
connector holes instead, which worked good when driven over a TCL
The little board just under the white inset lines is a self made 8 bit
DA converter with a R-2R network on a HC series chip, which is driven
by the FPGA which connected to the signals from the above addition to a
S90 synth so that in 8 bits the DA sounds like that instrument!
I visited a lecture at the hilversum visual art academy from a A&R
manager of some relevance in holland, this is after the lecture:
Musical equipment and software
I got the sweetwater catalog from the US for free by
asking for it, which is cool, though it was a bit damaged by the mail
The plugin prices are the opposite of the synthesizer prices: quite
high! For instance these sony sequencer plugins, which in the sony
demos don't sound very special, but then again those are mpeg files:
a thousand bucks, well well. I make reverbs, too, which are NOT Open
Source (pretty much the only thing at the moment) and wich can sound
great on practical examples, even in surround setup very good.
Designing with the latest Xilinx software
Well, it's not a complete improvement only to go from ISE webpack 7.X
to 8.1, because the hierarchy list fully expands automatically (I use
not small designs), and the schematic editor window can't be detached
to use full screen effectively...
The above shows a blackfin DSP interface and a serial port interface
and a memory interface (which seems to make the blackfuin nterface with
physical 100Ohm series resitors mess up it seems. I recently saw a 'to
many signals switches simultaneously' per group warning somewhere deep
hidden in the ucf erros or so, maybe that doesn't help much either...
Some work I could do.
I played around a bit, it never hurts to get free software like block
design dialog boxes, for istance a clock switcher, but inf fact a lot
of blocks, even things like cordics and such:
So what happened to Sci Fi?
Well, I didn't read it after about 1981 or so, so I don't know!
Sure know the difference between the 70s captain Kirk and evertything
that followed it being soooo much lower quality and pleasure.
I have looked at this though, with some great music (banjo and such):
So a motor company supplies kitchens for television shows? Aha, in the
Mathematics and Experiments
When I was at Cern (1991 or so) for my work at the time, about
distributed computing, I met one of the makers of the Root package,
which exisits today:
At the time one had to use expensive UNIX workstations to do serious
computations with, like the HP720s, Digitals, Suns etc, nowadays one
can use a run of the mill 64 bit motherboard with a not expensive AMD
on it and get a free download of a package like ROOT which can then run
prety well and without much installation work on a perfectly decent
Another favorite of mine is texmacs, though I'm sure it is not perfect,
and maybe there are even better ways to run Maxima with a real time
formula layout interface:
The above is a solution to the well known 2d order differential
equation of harmonic motion. I test this because I have considerable
interest in solving electrical network equations symbolically, and
preferably using symbolic excitations and solving system responses.