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Thread: Pangolin Abstract Generator *ROCKS*

  1. #31
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    That hammer and nail analogy doesn't work. It's self-limiting. A music keyboard puts out MIDI, but that isn't the same as saying that MIDI implies a keyboard controller!

    I challenge the point about serial control, it's probably no more able than MIDI is for sending signals for laser controllers to use, and is harder to implement, excepting that many computers still have serial ports, a point which does nothing to address the ADC conversion for your control inputs.

    It's also why I challenged this idea that Pangolin's use of MIDI is all you need to consider, it almost certainly is not. MIDI is always more diverse than any single adaptation of it.

    First, look carefully at what kind of signals we should consider using it for. Obviously it is NOT analog waveforms. Neither serial OR MIDI could send those, you'd have local waveform or other fast signal generators in the laser controller itself. MIDI isn't for the neural feedback that controls muscles, it's for commands like 'turn left', 'step back', 'go this much faster' or whatever.

    It's obviously NOT limited in what control messages can be sent. All it is is a protocol for sending control and data bytes for those controls, using cheap well-established and reliable hardware.

    If you want to speed up the LFO in a Lissajous generator, you turn a knob. Obviously the LFO is an oscillator that uses gain and feedback to make it run, and this is local, but there is no reason a slow control can't tell it what speed to change to. This order CAN be sent through MIDI, it can be sent that way with more response than you can put into your hand to turn the knob.

    And the knobs can be fitted to your own customised control surfaces. Buy Doepfer's 'Pocket Electronics' or other simple boards to make whatever glorious kind of control surface you can imagine. Use a downloadable freeware program Doepfer provide to program your own MIDI control codes for each knob and switch if the inbuilt codes and preset control arrays aren't ideal already.

    The whole point of this is that it is NOT limited! Far from it. It's actually the only way that DIY projector-building people can go this far. Any other way, they'll be tied to the coat tails of those who can prototype and market a viable system from raw components. Doepfer did what they did to enable people to build their own analog synthesizers. We've already established in many discussions how close such control is applicable to laser control (that sound card thread, for example).

    What MIDI allows is a complete fly-by-wire system. Most of the possible nasties like data jamming and panic messages to shut things off have been developed for tens of years, for a an industry that includes expensive large live shows. There aren't many systems better suited, and probably none cheaper or easier to use.

  2. #32
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    I was going to leave that post but I should add more, I really want to drive home the point that MIDI is more than adequate, and is probably the best system to use.

    Lets say you want more controls than Doepfer's DIY board has. Easy: Get two, merge with a MIDI merge box. Job done. I think it might even have a merge and MIDI input built in! So you can chain as many as you want. A lot of this stuff is easy to find cheap on eBay now, you just need to think about it to know what to look for. Ideal pursuit for laser hobbyists whio already are adept at this, I imagine.

    Now, how many many manual controls can you control at once? I put it to all here that a practised musician can almost certainly handle more than anyone, and this was built for that task. It's definitely good enough. MIDI doesn't just solve the messaging and wiring system, it solves the ADC system for your actual controls, and it's been designed specifically with a performer's realtime interface in mind, for machine control.

    If a wheel that good exists, reach it and turn it to your use, don't reinvent it.


    EDIT:
    http://www.doepfer.de/pe.htm
    Last edited by The_Doctor; 06-29-2007 at 03:10.

  3. #33
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    Doc, I think you're overcomplicating the issue. We're talking about the suitability of using MIDI to control an analog synth verses controlling it manually using the very analog controls that make up the syth itself. I think MIDI introduces an extra step that adds complexity. Complexity is not a bad thing per se, but in this case it's unnecessary in my opinion.

    With MIDI you need to break up each adjustment into discrete steps that you then need to define in your MIDI communications. Granted, with 8 bit resolution you'll probably have plenty of detail so that the fine adjustment would be similar to what you'd get from turning a knob, but why introduce the extra step (and complexity) if it's not needed.

    I agree that your examples of mixing signals and working with multiple adjustments is valid. One can certainly make more adjustments with a single MIDI command than you could by using your fingers to make manual adjustments. But you need to ask yourself if that is really a benefit when it comes to an analog laser show effects generator...

    My experience suggests that analog lissajous effects are more about making subtle changes to one or two parameters at a time, rather than trying to tweak 15 different potentiometers all at once. In other words, it's unlikely that you'd need the multi-adjustment abilities of MIDI. I also believe that the analog music synthesizers you mentioned are a wholly different application where the additional control possibilities of MIDI make good sense. I just don't think that laser show abstract generators have a need, or a use, for the added complexity. (But music synths do.)

    It's not about re-inventing the wheel. It's about pushing a shopping cart through the grocery store to hold your groceries vs. driving your pick-up truck down the isles and loading your groceries in that. Remember that all the analog controls are still going to be there in the abstract generator. All you're doing is adding a control scheme to them.

    But hey, if you want to try to build a lissajous box out of off-the-shelf MIDI components - by all means give it a shot! Maybe you'll come up with a product noone else has conceived of. (If you do, be sure to post some pics of the output here so we can see how it looks!) In fact, using the additional signal mixing abilities of MIDI, maybe you can create some unique effects that haven't been seen before. But as a general rule, laser abstracts tend to be pretty simple constructs. And often a simple problem is best solved with a simple solution. (And indeed, past analog laser show products have all followed that mold.)

    Adam

  4. #34
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    On the face of it, adding a DAC to encode a control knob's output only to send it down a wire and convert it back to analog might sound daft, but an entire industry co-operated to take up SCI's invention of MIDI. Sequential Circuits International (they added that 'National' and abbreviated all later) made analog synths. They didn't do this because it was more complex, they did it because it was the ONLY way to keep it simple. The entire industry grabbed it joyfully with both hands and went away with it running, and didn't look back. Do you really want chains of analog wires in parallel, hanging off a complex bit of custom gear? Or would you rather have the chance that your gear and someone elses gear can easily talk together and do new stuff easily?

    Suppose you took your stuff to a gig or a laserists convention? Which method would you really want most? You don't need to define steps either, you just put 0-5V on an analog input and let it get on with it, Doepfer (and Peavey, and many others) have done all the hard work already. If you can send an analog signal into a laser mod input, you can use this stuff. Similarly, firms like Kenton Electronics (the Pro 2000 for example) make MIDI to CV converters. Not only can these tools put out analog signals for conversion, they add LFO's to do direct scan controls with if people want to play with that. That's not why I brought it up though, I'm just hoping that Pangolin and others will adapt the software to allow MIDI control of EVERY feasible signal in reach. Let the performer decide what does and doesn't make artistic sense.


    But you need to ask yourself if that is really a benefit when it comes to an analog laser show effects generator...
    Of course it is. For the exact same reason it benefits an analog synthesizer. People retrofit those things with MIDI all the time. There are companies whose existence depends on that trade. I'm sure they'd gladly do adaptations for analog laser scanning. This thread is about control of a digital system though, all you need there is a MIDI input and a driver, that's cheap stuff on a PC now. People are virtually giving away such things on eBay. Imagine being able to record your performance too, and edit it, and replay it, all from a very cheap sequencer, without even needing a host computer! All this can be done, and a lot more, using MIDI allows adapting of all kinds of weird and entertaining control and process devices.

    Anything but use of a good exisiting system IS re-inventing a wheel. What's more, it's probably making it a totally proprietary and PRIVATE wheel! Learn from the synthesizer industry. They did this because it saved them from oblivion. Instead of fragmenting into a morass of private protocols they buried the hatchet and took up what SCI let them use royalty free. DZurcher's point about a serial interface makes sense because that too is a widespread data link system, but it hasn't a hope of competing with MIDI if you want a realtime performace control system for human/machine interface. MIDI was made for that, and every report of its death has been premature because it continues to be the best scheme around for the job.

    My experience suggests that analog lissajous effects are more about making subtle changes to one or two parameters at a time, rather than trying to tweak 15 different potentiometers all at once. In other words, it's unlikely that you'd need the multi-adjustment abilities of MIDI.
    MIDI is ONLY a way to send control and data bytes! It's as complex or as simple as you choose. I won't repeat what I said before, I'll focus on one issue that your comment raises. I grant that 7 bits is crude, too crude for a lot of fine controls, but where you want just a couple of very fine controls, MIDI is entirely suited to do it. Instead of one data byte, send two. That's 14 bits. This is standard fare for MIDI, the protocol has a few defined 'continuous controllers' for this task. They're only reserved numbers in a range of values, you can play fast and loose with them. The thing to do is to let the end user decide. (Those Doepfer tools make this easy and extremely configurable). The instrument maker merely has to enable their system to respond to paired messages of this kind, in cases where 7 bits of control resolution isn't fine enough.
    Last edited by The_Doctor; 06-29-2007 at 08:51.

  5. #35
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    This is why I have always liked to use the "PM" series of live desks. They have the ability (and sufficiens knobs and switches) to modulate patterns on the fly. Actually, a dozen push buttons for effect (modulation) selection and 6 pots to adjust levels would be plenty.
    Last edited by QUAZAR; 07-28-2007 at 15:47.

  6. #36
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    A bit more thought on the subject. As stated earlier, I have always used live desks for shows. Mainly because I like the hands on approach to operating, I knew where every one of my stored 200+ "patterns" were locared and could find them in the dark without looking at the buttons.

    I also liked the ability to modify these at will, working live gives you the ability to react almost instantly to changes in the music, something not so easily done on a PC. Also, in Europe, beam shows are used much more frequently than graphic shows.

    I agree that a good "interface" is definitely required between operator and a PC if you chose to work this way. I know Pangalin do their Live keyboard but it is very expensive here. I am also unsure that it would give sufficient control over the abstract effects generator. What I believe is required to perform this task would be something like thiis idea below. This would give full control over 3 sets of oscilators. Simply choose an initial "Shape" and add effects as required.




    Here is a close up showing the details of each oscilator section in detail.


    Each section has 3 rotary encoders.

    1, Controls selection of modulation effect-
    e.g. Vertical Move, Horizontal Move, Spin, Rove, Pulse, Step Out, Step Rotate, Random

    2, Controls amplitude of effect

    3, Controls speed of effect

    A Backlit 2 line LCD display gives a readout of your selections. Usefull for making notes when good patterns appear, or trying to recreate one you accidently deleted. It is also essential to be able to see what you are selecting in the dark corner you are usually operating from.

    A lower set of buttons chooses a waveform which can be overlaid to these effects. This will provide an additional level of movement and are extremely effective.

    A further row of buttons gives basic command controls.
    Invert (inverts selected effect eg Spin C/W Spin C/C/W)
    Reset (sets all selections to 0)
    Save


    Three of these modules should fit nicely onto a standard 3U 19" panel and blend in nicely with Mr Pangolins live desk.

    Connection to a PC could be either RS232 or USB. This would make everything nice and dandy with no connectivity problems to almost any PC.

    This is the kind of interface that would tempt me to use a PC based system over a live desk. I also willingly offer my services as a Beta tester should this project move beyond my initial ramblings.

    If anyone needs additional info on these types of analogue control systems, please let me know. I can put them in touch with George McDuff at Chameleon Technology. He has almost 25 years experience in designing and building analogue laser desks. Fortunately for me, his workshop is only actoss the road form where I live.
    Last edited by QUAZAR; 07-28-2007 at 16:24.

  7. #37
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    Quote Originally Posted by QUAZAR View Post
    Mainly because I like the hands on approach to operating.
    Same here, I'm a huge fan of being able to take over what is going on with abstracts with a bunch of knobs and buttons. I'm not completely familiar with Pangolin's Live! console except that I know its a serial interface. And I'm not so sure that you can adjust abstracts with the console at all. A seperate box aside from the Live! console would be very nice but I think it would require alot more knobs and buttons than you might think. Here is a screen shot of the Pangolin abstract generator. I'm thinking it would need about 2 dozen knobs, a whole mess of buttons and the ability to still choose frames as waveforms from the console.
    Attached Thumbnails Attached Thumbnails ldabs1.JPG  


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