cook@gaia.UUCP (Forrest Cook) (01/25/88)
I was recently given a sample IC VCA chip known as an SSM2013. Does anybody out there know who makes this chip so that I can look up a data sheet? I have never heard of the SSM prefix. Also, while on the topic, does anybody have any suggestions for alternative low noise VCA ICs or circuits? I am planning to develop a stereo voltage controlled pan circuit. Thanks in advance... Forrest Cook WB0RIO
daveb@eneevax.UUCP (David Bengtson) (01/25/88)
In article <341@gaia.UUCP> cook@gaia.UUCP (Forrest Cook) writes: >I was recently given a sample IC VCA chip known as an SSM2013. Does >anybody out there know who makes this chip so that I can look up a data >sheet? I have never heard of the SSM prefix. >Also, while on the topic, does anybody have any suggestions for alternative >low noise VCA ICs or circuits? I am planning to develop a stereo voltage >controlled pan circuit. >Thanks in advance... Forrest Cook WB0RIO The SSM 2013 is a product of Solid State Micro Technology for Music Inc. ( Wheh!! ) Their catalog lists several chips that might be of interest VCA's VCO's Filters, etc. Hobby/ Retail Sales in the US are: Anchor Electronics 2040 Walsh Ave. Santa Clara CA 95050 408 727 3693 Technical Services 635 Eckhoff St. Unit K Orange CA 92668 714 634 2371 David Bengtson If you think that I speak for Laboratory for Plasma Fusion the University, I've got a Bridge University of Maryland to sell you :-) College Park Md 20742 {your keyboard} !uunet!mimsy!eneevax!daveb eneevax.umd.edu
wtm@neoucom.UUCP (Bill Mayhew) (01/26/88)
While I don't know about the SSM2013, the Signetics NE572 looks interesting. Signetics claims that a dynamic range of greater than 110 dB is possible. Residual noise is typically 6 uV for the device. The chip contains a gain cell, log amp, and output buffer. See page 15-17 of the 1982 (what can I say, I'm an Old Fart) edtion of the Signetics Analog Data Manual. --Bill
phil@osiris.UUCP (Philip Kos) (01/29/88)
In addition to the Solid State Music SSM2013 and Signetics NE570 and
NE572 (I think the 572 is either the low-noise version or stereo
version of the 570, but I'm not sure), just about any OTA (Operational
Transconductance Amplifier, ~= VCA) circuit, like the RCA CA3080 and
others, should work with a little glue. You may have to check data
sheets to find quiet enough versions.
I expect the SSM2013 has lots of peripheral circuitry designed to do
stuff that you may not need. I know the NE570/NE572 do; they were
designed to make building companders (like dbx noise-reduction boxes)
easier, which is why they contain the extra circuitry (log amp, etc.)
Bill Mayhew mentioned.
A section in Walter Jung's "Audio IC Op Amp Applications" (TAB books,
I think) contains a low-noise high-stability VCA designed around a
3080. It includes some pretty involved (to my mind, at least)
temperature compensating elements, suggesting that the older OTA ICs
like the 3080 aren't particularly stable, but it might be a good
starting point if you want to brew your own. 3080s are cheap.
In other news, Radio-Electronics recently ran a couple of quick blurbs
(one in the New Products section, the other in Don Lancaster's new
"hacker" column) on a "solid-state pot" IC which may be an attractive
alternative to using an OTA.
Serious electron heads out there: if I've said anything blatantly
wrong, please be gentle. It's been awhile since I've seen most of this
stuff. Also, I'm tracking this discussion.. if you have anything to
add to it, either post it to the net or cc: me a mail copy. Thanks in
advance....
Phil Kos
...!decvax!decuac!\ Information Systems
...!uunet!mimsy!aplcen!osiris!phil The Johns Hopkins Hospital
...!allegra!/ Baltimore, MDwtm@neoucom.UUCP (Bill Mayhew) (01/30/88)
Hi Max (et al), Really, the light bulb doesn't bother me; I was just making a silly comment. (sorry if I forgot the net-smiley face). Those old #47 pilot lamps really could be used for all sorts of neat stuff when you had a mind to... Point well taken that a twin tee won't under work ideal conditions. I found that using sloppily picked components is likely to yield a concoction that has a higher probability of oscillating when the power is switched on. Fortunately, most hobbyists can't afford an RLC bridge, thus odds are pretty good that there will be sufficient mismatch for the thing to actually work. Point also well taken that the twin tee exploits the nonlinearity of the transistor to provide AGC after a fashion. Well, with a cruddy transistor like the 2N414 that I mentioned that approach was reasonable. That is also why the output should be taken between the two capacitors on the tee, to minimize the harmonics sent to the output. A fun diversion for periods of rainy boredom would be to run the old twin tee through spice with ideal and then real world component values and see what happens. --Bill