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Hedefar
Joined: Feb 07, 2013 Posts: 15 Location: Denmark
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Posted: Thu Feb 07, 2013 4:01 am Post subject:
Any tips or schematics for building an advanced LFO? |
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Hello out there!
Yesterday, I took my little DIY Mutable Instruments Anushri and went to play with the modular boys in town. It was very inspiring.
One person had a big Doepfer setup and the other had a smaller setup with hand picked modules of different brands.
One module in particular got my attention:
The Bubblesound uLFO.
That thing is amazing. It's range for one cycle goes from approx an hour and way up into the audible range, at 3,6kHz, making it a nice oscillator and all in all, it is just a quite versatile module with many parameters and CV possibilities.
See it here: http://www.bubblesound-instruments.com/ulfo.html
And in action: http://www.youtube.com/watch?v=Zr2iVvYz6YE&feature=channel
The owner had two of them and especially when getting them to modulate each other, they produced some very impressive sounds that the big Doepfer rig with all its modules couldn't mimic.
I liked the sound of the uLFO as an oscillator much better than the Doepfer A110 even though being a VCO is not it's main goal.
I crave that Bubblesound uLFO... but being a student, price is an issue, so I am looking for a way to build one.
I am no engineer and cannot design one myself. Not yet, anyway. But maybe some of you know of advanced DIY projects for something similar to this?
Thanks for taking your time!
//Hedefar |
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Uncle Krunkus
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Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
Audio files: 52
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Posted: Thu Feb 07, 2013 5:23 am Post subject:
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I've had two ideas about this,
1. An old idea about a module based LFO/EG. You stack the modules next to each other to create different slope speeds between stages. To make a complex LFO, you loop the output back to the start. The timing for each stage could be chargetime related, or it could be forced by a digital timing signal, (works kinda like a sync on a VCO but at low frequencies)
Gate, and/or trigger signals can force or hold up any stage, (for Envelope generator applications)
and,.........
You can add as many stages as you like.
2. A lot simpler, (and newer) idea is a 4017 cycling/resetting/changing steps, with a 100K pot from each output to ground, (Event Horizon style) wipers summed into a TL072 buffer with a glide cap on the feedback, adjustable. Other op-amp gives an inverted output.
Actually, with a TL074 you could get all four:-
Normal
Inverted
Glide
Glide inverted
Three chips and it's done.
If you use a 40106 for the main clock/trigger in processing, that still leaves 4 inverters to send the opposite to the summer, or not, I think.
Which kinda makes it a bit Klee Sequencer, but on a much simpler level. The Klee is, by the way, a really cool complex LFO if you hook it up that way. _________________ What makes a space ours, is what we put there, and what we do there. |
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Hedefar
Joined: Feb 07, 2013 Posts: 15 Location: Denmark
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Posted: Thu Feb 07, 2013 6:30 am Post subject:
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Thanks for the reply Uncle Krunkus
I'm afraid you are quite a bit above my level though. I'm new to DIY and so far I just assembled a Shruti-1 and an Anushri by following the written instructions closely.
But I will take my time to read up on the different components you mentioned. It will probably learn a lot from it
And I will check out the Klee as well.
Thanks for helping out!
//Hedefar |
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L´Andratté
Joined: Sep 23, 2012 Posts: 150 Location: Hamburg, Germany
Audio files: 5
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Posted: Mon Feb 11, 2013 4:48 pm Post subject:
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Hi! If you´re a beginner you should try building a cmos lfo with the 40106 chip uncle krunkus is mentioning (they are easy to get).
Actually such an LFO recently posted in the delay circuit by papaver yesterday
in his stylo-stereo-delay http://electro-music.com/forum/phpbb-files/jellyfish_schematic_143.jpg
the part that´s in the left lower corner repeated twice, it´s not exactly an advanced LFO but a very nice beginner circuit, with different timing capacitors can do wide freq range and in fact the ken stone psycho lfo is just this thing six times and intermodulating and THAT is a very cool module!
now time togo to sleep for me! |
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Hedefar
Joined: Feb 07, 2013 Posts: 15 Location: Denmark
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Posted: Tue Feb 12, 2013 2:54 pm Post subject:
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Hey L´Andratté,
Thanks for the info. Sounds interesting!
I will definitely look into that!
Cheers! |
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bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
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Posted: Wed Feb 13, 2013 6:19 am Post subject:
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arduino + dac _________________ _Richard_ |
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Uncle Krunkus
Moderator
Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
Audio files: 52
G2 patch files: 1
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Posted: Wed Feb 13, 2013 8:03 am Post subject:
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bubzy wrote: | arduino + dac |
I'd like to try an Arduino one day, but at the moment it's just not in my budget to set it all up.
_________________ What makes a space ours, is what we put there, and what we do there. |
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Hedefar
Joined: Feb 07, 2013 Posts: 15 Location: Denmark
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Posted: Wed Feb 13, 2013 8:51 am Post subject:
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Yes, Arduino has been in my mind for quite some time now. I will probably dig into it at some point. A lot of possibilities seem to come with those little things! |
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bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
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Posted: Wed Feb 13, 2013 10:56 am Post subject:
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Uncle Krunkus wrote: |
I'd like to try an Arduino one day, but at the moment it's just not in my budget to set it all up.
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well, you can buy an atmega328 with the arduino bootloader, a usb>serial doodad, a crystal and 2 caps pretty cheap, and whammo! a diy arduino for about 1/6th of the price of a "proper" one.
_________________ _Richard_ |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Posted: Wed Feb 13, 2013 1:55 pm Post subject:
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My first arduino was a "Mintduino" which is the ATMega chip, all the support necessary, a small breadboard, all in a mint tin.
I think it was $20. In my case I did spend another $25 on the FTDI chip to do the USB programming, but today you can buy a Leonardo for $20 that has the USB built in.
US prices, of course.
MCP4922 DAC gives you serial access to a 2 channel DAC for $5 or so. |
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Hedefar
Joined: Feb 07, 2013 Posts: 15 Location: Denmark
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Posted: Fri Feb 15, 2013 12:36 pm Post subject:
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Great!
Thanks for the tips, guys! |
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cloudscapes
Joined: Feb 09, 2004 Posts: 100 Location: Montreal
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Posted: Sun Feb 17, 2013 3:09 pm Post subject:
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elmegil wrote: |
MCP4922 DAC gives you serial access to a 2 channel DAC for $5 or so. |
I prefer the PT8211 DAC
It's 2 channels, about $0.50 on ebay, 16-bit, lower pin count and faster. I use it for anything between full audio to CV/LFOs. _________________ Sonic Crayon DIY effects lab |
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bubzy
Joined: Oct 27, 2010 Posts: 594 Location: United Kingdom
Audio files: 64
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Posted: Mon Feb 18, 2013 2:02 am Post subject:
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that is a nice chip!
no spi though :/
*buys some* _________________ _Richard_ |
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Uncle Krunkus
Moderator
Joined: Jul 11, 2005 Posts: 4761 Location: Sydney, Australia
Audio files: 52
G2 patch files: 1
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Posted: Mon Feb 18, 2013 4:25 am Post subject:
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Hedefar wrote: | Yes, Arduino has been in my mind for quite some time now. I will probably dig into it at some point. A lot of possibilities seem to come with those little things! |
How about an LFO whose waveshape is analogus to an iteration graph across the mandelbrot set where the origin is set by two incoming CVs and the angle of the slice is set by a third CV, driven by another LFO!! _________________ What makes a space ours, is what we put there, and what we do there. |
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cloudscapes
Joined: Feb 09, 2004 Posts: 100 Location: Montreal
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Posted: Tue Feb 19, 2013 7:00 pm Post subject:
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bubzy wrote: | that is a nice chip!
no spi though :/
*buys some* |
which one, the 8211? I could interface to it easily enough via SPI and a couple manual pin toggles _________________ Sonic Crayon DIY effects lab |
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johncronan
Joined: Feb 24, 2013 Posts: 42 Location: Chicago
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Posted: Sun Feb 24, 2013 6:25 pm Post subject:
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The MOTM-320 is what I would call an "advanced LFO." CVable (freq and shape), temperature compensated, very wide range. Synth Tech has a nice manual that you can download here. You would certainly be able to save a fair bit of money over the Bubblesound if you bought the PCB from Bridechamber for 40 bucks and sourced the other parts yourself. |
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