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Rob
Joined: Mar 29, 2004
Posts: 580
Location: The Hague/Netherlands/EC
G2 patch files: 109
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blue hell
Site Admin
Joined: Apr 03, 2004
Posts: 24382
Location: The Netherlands, Enschede
Audio files: 296
G2 patch files: 320
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 Posted: Thu Dec 07, 2006 2:42 pm Post subject:
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I'm sure I don't understand how it works, and not just because it makes me want to sit on the sofa with a glass and smoke 
_________________
Jan
also .. could someone please turn down the thermostat a bit.
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Rob
Joined: Mar 29, 2004
Posts: 580
Location: The Hague/Netherlands/EC
G2 patch files: 109
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| Posted: Thu Dec 07, 2006 4:45 pm Post subject:
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| Blue Hell wrote: | | I'm sure I don't understand how it works, and not just because it makes me want to sit on the sofa with a glass and smoke |
Well, what I wanted was a frequency shifter where I can morph the controlling sine/cosine osc into other waveforms. Basically a frequency shifter is like a ringmodulator but with separate lower and upper sidebands available. (Jan, I know you know this but maybe others don't.) It works by using two ringmodulators and waveforms where all the partials have a phase difference of 90 degrees. Regrettably the G2 does not have a separate osc module that provides these two waves and the frequency shifter module does only work with an internal sine/cosine oscillator where the waveform cannot be morphed into something with more harmonics. So, I had to patch such an osc myself.
In fact, this oscillator is a digital emulation of an analog sine<->saw osc that I once designed and have used in those 'blippoboxes'. This osc is a biquad-type oscillator, meaning that it has two stages (the 'bi' in biquad) that produce a phaseshift of 90 degrees (which is the 'quad' of 360 degrees) plus an inverter (the remaining two quads) in the oscillation feedback loop, which has a gain of a little over unity to make the loop oscillate and a slight HF damping to not make it also oscillate at half the sample rate. In the feedback loop is also a limiter to keep the oscillation stable. An analog version always starts to oscillate due to the little noise always present in such a circuit, but the digital version has to start by feeding it just a little bit of noise. The digital emulation regrettably stops oscillating at a couple of kiloHertz, which is caused by some bandwidth issues I will not go into this time. In contrast, my analog design can produce a stable waveform from half a Hertz up to 50 kHz when quality components are used.
This oscillator produces both a sinewave and a cosine wave at the outputs of the two 'quad' stages (allpass filters are used to really get 90 degrees phase shift in each stage). By additionally using LinFM selfmodulation the waveform can be morphed between a reasonably pure sine and a waveform containing a series of all harmonics, like those in a sawtooth waveform. But as the harmonic series is build up from the fundamental it gives quite a warm sound, like a softly filtered traditional sawwave. The selfmodulation has to be linear and it has to pass though a highpass filter to avoid unwanted detuning and keeping the modulation index reasonably constant over the frequency range. The interesting thing is that when this selfmodulation is applied all partials in the two outputs still have that 90 degree phase difference relation and so such a waveform can be used to drive a frequency shifter. This gives the frequency shifter a more 'vintage ringmodulator' sound and makes it nice to process percussive sounds and spacey drones.
There are four of these biquad oscillators in the patch. The allpass filters are made with a crossfader and a mixer subtracting twice the output of the crossfader (basically a 6dB lowpass filter) from the input. The crossfader is used as this one can be modulated linearly and the standard -6dB lowpass filter modules cannot.
Two multimode 'state variable' filters are used to create a 'twin peaks' percussive element. The nice thing about these filters is that the phase difference between the BP and LP output at resonance is also 90 degrees, and can so be used in the frequency shifter circuit without having to patch a Hilbert-transform phase shifting network.
Doing it this way there are many extra control points, knobs and modulations possible compared to the standard frequency shifter module. Knobs and modulations that all seem to enhance that fifties type of 'Forbidden planet' sounds that I personally like quite a lot.
When I had this working it was just too tempting to add some distortion, some echo and some other little ditties, and then I had to go to do real work for money. But before I went out I thought it nice to publish the patch, just as it is quite experimental. And I probably should post much more experimental patches. 
Jan, now that you had your smoke and drink, followed by these hints, I guess it is not so difficult to figure out, it is actually quite structured. So, I do expect a 'verkrachte versie' some time soon. 
Have fun,
/Rob |
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blue hell
Site Admin
Joined: Apr 03, 2004
Posts: 24382
Location: The Netherlands, Enschede
Audio files: 296
G2 patch files: 320
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| Posted: Thu Dec 07, 2006 5:13 pm Post subject:
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Well, I seem to have someting to do next weekend
Thanks for explaining !
_________________
Jan
also .. could someone please turn down the thermostat a bit.
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jksuperstar
Joined: Aug 20, 2004
Posts: 2503
Location: Denver
Audio files: 1
G2 patch files: 18
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| Posted: Thu Dec 07, 2006 7:43 pm Post subject:
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The 99.7% memory limit...did you hit the wall and have to scale back, or did you keep patching until she just couldn't take any more?
Turning up the polyphony gets some nice comb filtering and even audible delays. Very Nice. |
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maitilupas
Joined: Jul 25, 2008
Posts: 28
Location: Netherlands
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| Posted: Wed Nov 24, 2010 6:22 am Post subject:
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Incredible! this is an inspiring Patch
only dont have enough expanded memory to run it all , but the most important is the 2nd patch for me
and by the way i was your student in 2006, and i am very greatfull many thx
Jose |
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blue hell
Site Admin
Joined: Apr 03, 2004
Posts: 24382
Location: The Netherlands, Enschede
Audio files: 296
G2 patch files: 320
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| Posted: Wed Nov 24, 2010 6:44 am Post subject:
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 I see I'm still on that bloody sofa  after all those years.
Edit : hmm .. the patch archive - or the attachment archive is corrupted it seems - nothing demo friendly on that patch .. prolly it got lost in the 2007 crash and the file id was taken later by some other patch .. which opens as a performance even when named as a pch ... weird ... and just now I finally got off that sofa
Edit2: tried to fix it, but the patch is really gone .. sorry.
_________________
Jan
also .. could someone please turn down the thermostat a bit.
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v-un-v
Janitor
Joined: May 16, 2005
Posts: 8933
Location: Birmingham, England, UK
Audio files: 11
G2 patch files: 1
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| Posted: Wed Nov 24, 2010 1:12 pm Post subject:
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Hey Jan, thanks for finding this patch again after all these beers!
I remember loading this into the demo G2 all those years back and sitting back in amazement! (wouldn't work on the Mac version though- only the PC one  )
I still need/want a G2.
_________________
ACHTUNG!
ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!
DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKSEN.
IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.
ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN. |
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blue hell
Site Admin
Joined: Apr 03, 2004
Posts: 24382
Location: The Netherlands, Enschede
Audio files: 296
G2 patch files: 320
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| Posted: Wed Nov 24, 2010 1:26 pm Post subject:
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Oh if you still have the patch Tom (or Rob, or someone else) .... could you post it?
And of course it was not me but maitilupas to stir it up 
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Jan
also .. could someone please turn down the thermostat a bit.
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maitilupas
Joined: Jul 25, 2008
Posts: 28
Location: Netherlands
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| Posted: Wed Nov 24, 2010 1:49 pm Post subject:
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I also found it strange a pch extension opening as a performance
I became curious to see this patch working after seeing the " tapeechosounds_143.pch2"
luckily someone will post it here
thx |
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v-un-v
Janitor
Joined: May 16, 2005
Posts: 8933
Location: Birmingham, England, UK
Audio files: 11
G2 patch files: 1
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| Posted: Thu Nov 25, 2010 3:26 am Post subject:
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I have lost the patch. Sorry
_________________
ACHTUNG!
ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!
DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKSEN.
IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.
ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN. |
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ian-s
Joined: Apr 01, 2004
Posts: 2672
Location: Auckland, New Zealand
Audio files: 42
G2 patch files: 626
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blue hell
Site Admin
Joined: Apr 03, 2004
Posts: 24382
Location: The Netherlands, Enschede
Audio files: 296
G2 patch files: 320
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| Posted: Thu Nov 25, 2010 2:05 pm Post subject:
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Brilliant  thanks Ian.
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Jan
also .. could someone please turn down the thermostat a bit.
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maitilupas
Joined: Jul 25, 2008
Posts: 28
Location: Netherlands
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| Posted: Thu Nov 25, 2010 3:08 pm Post subject:
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thank you,
lets see what Jan was talking about the Sofa now |
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maitilupas
Joined: Jul 25, 2008
Posts: 28
Location: Netherlands
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iPassenger
Joined: Jan 27, 2007
Posts: 1068
Location: Sheffield, UK
Audio files: 5
G2 patch files: 78
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| Posted: Fri Nov 26, 2010 12:32 am Post subject:
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| ian-s wrote: | | I found this on my old laptop. |
Nice one, I was wanting to have a look at this after reading Rob's description. I'd figured it wasn't really possible to make your own freq shifter on the G2 but clearly I was wrong. 
_________________
iP (Ross)
- http://ipassenger.bandcamp.com
- http://soundcloud.com/ipassenger |
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