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mother misty
Joined: May 13, 2004 Posts: 681 Location: Ghent / Belgium
Audio files: 82
G2 patch files: 130
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Posted: Thu Jul 08, 2004 12:03 am Post subject:
Frequency Shiter in v1.2 |
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Hi all!
Anybody knows why the 'mix' output from the Frequency Shifter
in v1.2 has dissapeared? It now only has 'up' & 'down'.
I have some v1.1 patches who used that 'mix' output, when you load those in v1.2 they have no output connection
Other than that... very nice update!
The new noise Osc's, the Random modules, the scratcher, the pitchshifter... Can't wait to try those. |
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ian-s
Joined: Apr 01, 2004 Posts: 2669 Location: Auckland, New Zealand
Audio files: 42
G2 patch files: 626
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Posted: Thu Jul 08, 2004 12:54 am Post subject:
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Yes, my barber pole flanger patch (and some others) used the mix output so that a control signal could change the direction of the flanging. The help file points out how it can be replaced with the xfader. Not too much work I suppose. Glad I never figured out a use for the 90-degree output
Another head scratcher is the new mode on the clock divider module. It gives the divided signal the same duty cycle as the input. Interesting, but it is the default mode, so patches that rely on the old behaviour wont work until you select the second (or 50%) mode. Probably some sound technical rational behind that, but it escapes me at the moment. It has broken a couple of my posted patches but only takes a little effort to fix. |
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mother misty
Joined: May 13, 2004 Posts: 681 Location: Ghent / Belgium
Audio files: 82
G2 patch files: 130
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Posted: Thu Jul 08, 2004 4:46 am Post subject:
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you can indeed patch the outputs to a x-fader module,
but isn't it a bit stupid that you have to use an extra module
which causes more patchload? |
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
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Posted: Thu Jul 08, 2004 11:23 am Post subject:
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mother misty wrote: | you can indeed patch the outputs to a x-fader module,
but isn't it a bit stupid that you have to use an extra module
which causes more patchload? |
The shifter itself supposedly was stripped to make it cheaper DSP wise, isn't that the case ?
The default mode for the divider being wrong probably was due to 'hectics' before the release, it was one of the things changed at the very last moment. Simple thing, couldn't go wrong, you know :-)
Jan. |
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mosc
Site Admin
Joined: Jan 31, 2003 Posts: 18197 Location: Durham, NC
Audio files: 212
G2 patch files: 60
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Posted: Thu Jul 08, 2004 12:07 pm Post subject:
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I too am taken aback by the changes in the frequency shifter. It seems needless to me, and it makes patches break. The 90 degree phase shifter can be very useful and there is no way I know to achieve this now that they have taken it out.
Please don't ask me to give you an example of what musical thing you can do with a 90 degree phase shifter, but if you look in a communication theory textbook, you'll see that a as a very common module in building filters and modulators of various types. I'm sure there are many musical applications even if I can't think of any at the moment. |
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
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Posted: Thu Jul 08, 2004 2:00 pm Post subject:
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I agree that it's not very nice to break existing patches, I'm not really happy with that either ... but we'll have to make the best of it now.
On the 90 deg. phase shift :
We now have an audio osc with true phase modulation and a sync input.
Using a plain sine osc (OSC A or something) and the PM osc set to a sine and to a 90 deg phase shift and connecting the simple sine output to the sync input of the PM osc and having set both oscs to the same frequency (linking their pitch inputs to the same control signal) should give you what you want I'd think. Am I wrong ?
I don't have any examples either on how to use these signals but you are right Howard it is in the text books. I remember that long ago for a university course I had to do some experiments with filters and 90 deg. phase shifted signals. I think the experiment was meant to give some insight in complex numbers (of the form a + bi) and how to apply them to filter theory.
In practice it was just quite tricky to get it working, and it didn't demonstrate a thing to me at that time.
Jan. |
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mosc
Site Admin
Joined: Jan 31, 2003 Posts: 18197 Location: Durham, NC
Audio files: 212
G2 patch files: 60
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Posted: Thu Jul 08, 2004 2:36 pm Post subject:
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Having an oscillator with a 90 degree phase shift is one thing, but to have an all pass network that will do this on any arbitrary signal is another. If I remember, I have seen ciruits that do this by using a large number of band pass filters and then passing these narrow band signals though a phase shifter network designed for each particular frequency. The these are mixed to make the 90 degree shifted signal. Of course, there would be quite a bit of error with this kind of circuit.
To get just the upper and lower sidebands from a multiplier, you have to use 90 degree shifters internally, so Clavia has a method of doing this digitally. |
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blue hell
Site Admin
Joined: Apr 03, 2004 Posts: 24079 Location: The Netherlands, Enschede
Audio files: 278
G2 patch files: 320
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Posted: Thu Jul 08, 2004 3:18 pm Post subject:
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mosc wrote: | Having an oscillator with a 90 degree phase shift is one thing, but to have an all pass network that will do this on any arbitrary signal is another. |
That's indeed what the 1.1 manual says the outputs did, I'd thought it would have been operating on the internal osc. Should have looked that up first, I forgot you are a radio specialist :-)
How is a 90 deg phase shift defined for arbitrary signals ? Are we talking stricly repeating signals here ?
Jan. |
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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 Jul 08, 2004 3:21 pm Post subject:
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One application I know is to use a multiplier on the 0 and 90 degree outputs, which results in a 'broadband' frequency doubler. Sort of to create the 'Donald Duck' voice. I once heard it was done that way, though I have no proof this is true.
So, probably Clavia wanted to do us a favour and save us from a new Cher number one hitsingle where she sings with a 'Duck' voice.
But the Mix knob & output gone is a bloody shame. I guess they wanted the module to look like the chorus and phaser modules from the FX group. Which is a dangerous development, when graphic design gets more priority than sound. Clavia shouldn't make a habit of this. Another example is the AM inputs on oscillators. These were damn convenient on the classic NM. Its a shame they didn't return on all oscs, 'cause they don't look good'. As that could have been the only reason. |
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ian-s
Joined: Apr 01, 2004 Posts: 2669 Location: Auckland, New Zealand
Audio files: 42
G2 patch files: 626
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Posted: Thu Jul 08, 2004 7:30 pm Post subject:
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Blue Hell wrote: | The default mode for the divider being wrong probably was due to 'hectics' before the release, it was one of the things changed at the very last moment. Simple thing, couldn't go wrong, you know
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I know how it is, a thousand things to do, deadline come and gone. I used to program for a living.
I think overall, a great job has been done by Clavia, and the Beta testers.
The only application I know for sure that requires the 90' phase shift network is a frequency shifter But you can create a good frequency shifter without one, just using more quadrature oscillators and multipliers.
Was going to do some research but Clavia have saved me some time. |
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mosc
Site Admin
Joined: Jan 31, 2003 Posts: 18197 Location: Durham, NC
Audio files: 212
G2 patch files: 60
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Posted: Fri Jul 09, 2004 8:39 am Post subject:
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g2ian wrote: | The only application I know for sure that requires the 90' phase shift network is a frequency shifter |
I remember seeing these used in quadrature modulation and demodulation schemes that are used like crazy in modems. Funny, who would use the G2 to design modems? |
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