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Re: Henry Smooth Phaser Schematic

11/3/1998 5:18 AM
Paul Perry
Re: Henry Smooth Phaser Schematic
Some early leds have degraded due to moisture diffusion into the plastic casing. perhaps this has happened with old CLM's?  
In any case, OTA's only match 2 to 1. I think by putting a variable resistor in parallel wwith a LDR, and another in series, you can tweak it to be matched at 2 points on the curve..... perhaps it would then be close enough over the rest of the range.  
My own inclination is to go for the ultrasonic switched resistor technique, easy to get accuracy of 1%!!!!
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11/3/1998 6:58 AM
Mark Amundson

Tom and I did not take phaser design beyond the CLM600 application. Due to Tom's finances and current busy teaching schedule, he is not likely to rejoin the development.  
If you want to further DIY kit effort that Tom Henry and I started, get Tom's blessing and I will help you if needed. Based on my listening tests, my preference on variable resistance elements is the dual CdSe cell vactrol parts that seem to have good matching.  
Mark Amundson,  
11/18/1998 10:27 AM
Mark Hammer
Substitute for SSM2040?
The SSM2040 chip provides an exremely easy way to implement a 4-stage phaser with small space requirements and decent sonic characteristics, but is no longer available as anything other than NOS.  
I was glancing at a schematic for the Roland MC-202 from one of the synth sites the other day and noticed a chip numbered IR3109 in the VCF section that seems virtually identical to the SSM2040 4-pole filter chip. The schematic does not appear to use house numbers at all, so I imagine the number listed is the actual commercial part number.  
It is NOT pin for pin replaceable with the SSM2040, but shares the same general function (4 CV-linked-but-separable cascadable OTA's) with apparently similar parameters, given the values of the external components.  
Anyone know anything about this chip? Do the prefix letters ring a bell? Could this be something to resurrect the Smooth Phaser with a small change in the PC layout?
11/28/1998 2:42 PM
John J
I am not to sure Mark due to the lack of reference. Yet I think the SSM is a digital device abreviation and the number is from a chip known as a bucket brigade device. Digi-key has them in there MN30XX series.Digital Device # is 1-800-DIGITAL. Again without reference before me I am just speculating. Good Luck, John J
11/28/1998 3:18 PM
Mark Hammer

I appreciate the effort, but no, that ain't it. The SSM chips (which Active/Future electronics carries) are designed by Solid State Music, and (I think) manufactured for them by Exar or AMD. The SSM line is still in production (used for mic pre-amps in high-end mixers, and a number of synth circuits), but the SSM2040 kind of disappeared around 1983.  
The chip I noted in one of my postings about this thread - the IR3109 - seems to be the functional equivalent of the SSM2040, but I have no idea who makes it, or if it is still made.  
Although the SSM2040 was used as a 24db/octave lowpass filter in most commercial applications, it was essentially 4 nondedicated sections that you could tweak to your own will. Two phase shift sections and a 2-pole highpass filter on a chip? No problem. 4-stage phase shifter? No problem. 2-pole lowpass and 2-pole highpass? No problem. Blacet Electromusic used to have a kit based on the 2040 called the Phasefilter that was multiconfigurable but tended to provide a lowpass filter and notch tied to voltage-control circuitry.  
The MN30xx series is a decent set of chips, but not even close enough to get a picture of a cigar. Again, thanks for trying.
11/29/1998 12:57 AM
Paul Perry

The IR3109 isn't in the Chip Directory, which is bad news, usually.  
The SSM stuff was taken over (twice) and Analog Devices in their wisdom dropped all the useful ones, except a couple of VCA's. They have added more SSM prefix chips for microphone/preamp type things, but nothing useful for fx.
11/29/1998 12:36 PM
John J.
sorry Mark.

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