Roland MC-500
Saturday, July 14, 2007
Roland SPV-335 Manual
Title link takes you to a scan of the manual. It's also available on the Roland site, however, for those of you that do not want to create an account and log on, here you go.
An XR-2206 Non-Hint
via Thomas Henry on electromusic-com:
"In my VCO Chip Cookbook, I mention that the four quadrant multiplier in the XR-2206 would be lousy as a VCA. In fact, I had a chance to find out just how bad it is this past week.
I've developed a rather unusual electronic percussion synthesizer with no commercial equivalent, and among the chips in it is the XR-2206. Somewhere along the way in the design cycle I thought I might use the internal multiplier as a VCA and save a chip or two. I figured, even as bad as I knew it to be, it would be okay for percussive sounds.
In a nutshell, no way! Even for simple VCA applications, this chip stinks. There are several problems. First, "off" means down -55dB which is still very audible. Second, it's hard to find "off" in the first place---it corresponds to a control voltage around 1/2V+, meaning that a trimmer will be needed. Third, even in the "off" position, the amount of background hiss is quite objectionable.
Like I say, I thought I might get away with it in this situation, but it's clear the unit is abysmal even as a simple VCA for percussion.
However, the story has a good ending. I wound up using the multiplier as a ring modulator, and in this context it's great! I probably wouldn't have considered that option before, but didn't want to waste part of the chip.
So again, in the XR-2206: VCA no, ring modulator yes. I hope this saves someone else a wasted evening pursuing that which doesn't exist! By the way, the new circuit is the most difficult one I've ever pulled off. It took a solid 14 twelve-hour days to get it right. See what I do for summer vacations!
Finally, I figured out another way to put the XR-2206 under exponential control. (There's one version in the VCO Chip Cookbook that is particularly powerful, but this new method is ideal for non-critical applications like tuning the drums via a keyboard). When I get a chance, I'll draw it up and share it here.
Thomas Henry"
"In my VCO Chip Cookbook, I mention that the four quadrant multiplier in the XR-2206 would be lousy as a VCA. In fact, I had a chance to find out just how bad it is this past week.
I've developed a rather unusual electronic percussion synthesizer with no commercial equivalent, and among the chips in it is the XR-2206. Somewhere along the way in the design cycle I thought I might use the internal multiplier as a VCA and save a chip or two. I figured, even as bad as I knew it to be, it would be okay for percussive sounds.
In a nutshell, no way! Even for simple VCA applications, this chip stinks. There are several problems. First, "off" means down -55dB which is still very audible. Second, it's hard to find "off" in the first place---it corresponds to a control voltage around 1/2V+, meaning that a trimmer will be needed. Third, even in the "off" position, the amount of background hiss is quite objectionable.
Like I say, I thought I might get away with it in this situation, but it's clear the unit is abysmal even as a simple VCA for percussion.
However, the story has a good ending. I wound up using the multiplier as a ring modulator, and in this context it's great! I probably wouldn't have considered that option before, but didn't want to waste part of the chip.
So again, in the XR-2206: VCA no, ring modulator yes. I hope this saves someone else a wasted evening pursuing that which doesn't exist! By the way, the new circuit is the most difficult one I've ever pulled off. It took a solid 14 twelve-hour days to get it right. See what I do for summer vacations!
Finally, I figured out another way to put the XR-2206 under exponential control. (There's one version in the VCO Chip Cookbook that is particularly powerful, but this new method is ideal for non-critical applications like tuning the drums via a keyboard). When I get a chance, I'll draw it up and share it here.
Thomas Henry"
Fantasy Rondo In A Minor
YouTube via Goldenthrush.
"A slow, strong piece, thoughtful and beautifully performed. This is a Jackson guitar using a Roland GR-20 guitar synthesizer, one of Tedd's best works. The audio can be downloaded here. The footage is taken from "A Trip Down Market Street 1905", also from the Internet Archive, I urge you to view that version, as I ended up clipping off several minutes of it for this purpose. This is San Francisco before the earthquakes."
MOTM Modular
Click here for additional shots via this auction
* MOTM-300 ULTRA VCO Quantity 3
* MOTM-120 SUB-OCTAVE MULTIPLEXER
* MOTM-101 NOISE/S&H
* MOTM-410 TRIPLE RESONANT FILTER
* MOTM-440 DISCRETE OTA LOWPASS FILTER
* MOTM-800 EG Quantity 2
* MOTM-320 VOLTAGE-CONTROLLED LFO
* MOTM-110 RING MOD/VCA
* MOTM-900 POWER SUPPLY
* MOTM-940 PATCH PANEL
PAiA 2720
Click here for shots via this auction
"This auction is for a 1974 Paia model 2720 Modular Synthesizer. The synth includes 13 patch cables and 5 audio cables and a complete set of manuals for every module as well as the assembly instructions, patch diagrams, and a user manual.
The 2720 was sold as a kit of parts and was the first synth to incorporate, in one unit, its own power supply, all electronic analog music modules and an integral keyboard controller. As opposed to earlier models, it can literally be moved to any location and simply plugged in. The synth was designed by John Simonton, Paia founder. The synth is completely operational and like new with the following flaws noted:A rubber foot on the front right corner has disintegrated.
The low 'B' key on the controller sticks a little.
Keyboard calibration is off and needs to be re-aligned (a periodic task)
The synth has not been used for many years, but was recently activated to record some vintage sounds. The synth has a lot of historical value and is extremely educational since it uses very basic components to electronically generate sounds. I am the original owner and builder and now need the space for some more equipment. Here are the components of the 2720:
Power Supply - with variable outputs
VCO - Voltage Controlled Oscillator w/3 wave shapes
ASD - forerunner to the ADSR called a Function Generator
LFO - Low Frequency Oscillator w/ 3 bands and variable frequency
Noise generator
Band Pass Filter w/Q control
Low Pass Filter w/control
VCA - Voltage Control Amplifier w/ control
Keyboard Controller
Variable Pitch and Trigger shapes for the Keyboard Controller
More info on this synth can be found at JohnnyPumphandle.com Shipping weight is about 20 pounds"
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© Matrixsynth - All posts are presented here for informative, historical and educative purposes as applicable within fair use.
MATRIXSYNTH is supported by affiliate links that use cookies to track clickthroughs and sales. See the privacy policy for details.
MATRIXSYNTH - EVERYTHING SYNTH
