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Bringing vintage dynamics processor to life.

George Ellias
Prodigy 60 points
Other Parts Discussed in Thread: LM1894

Hey, I'm looking at a vintage  suppressor / expander  someone yanked the original chips out of it, however the original if sockets are Texas Instruments.  I believe  there is some kind of 16 pin compandor that belongs in here. Did TI ever make any kind of compandor with 16 pins? This unit dates back to 1980, from what I've been told.  It's a  dynamics processor/noise reduction system.

  • 0
    TI__Guru* 93105 points

    Hi George,

    I searched the TI website and didn't find any references to TI compressors, expanders, or companders, listed. However, with the National Semi acquisition by TI the company did pick up the LM1894:

    Probably the most popular and applied compander products in the 1980s were the Signetics NE570/571/572 products. These were second-sourced by several companies, but I am not finding any evidence that TI did that.

    Regards, Thomas

    PA - Linear Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 60 points

    Hey, thank you for responding so promptly. I had to put the project down for a week because of other priorities.


    -I gathered that information this far... but what is strange is that the IC sockets are printed with a TI logo.


    I've patched in a NE571 compander by Philips, but the signal distorts still. I'm going to try the NE572, as i've heard from sources that it does not have an internal op-amp, like the NE571 or NE570. Perhaps that extra op-amp is driving the circuit after compression, causing the harsh clipping distortion rather than the smooth. transparent compression that it is designed to give.


    By any chance did TI have a 14 pin VCA chip around that time? I can upload a couple pictures of the unit if that will help.  I'll also circle where the empty TI sockets were when I picked it up.

  • 0 in reply to George Ellias
    TI__Guru* 93105 points

    Hi George,

    When I check the VCA offerings I find them in 8-pin and 48-pin packages, and serving very different functions. You could try searching the TI webpage and see if you find anything that might fit:

    You can load some images of the board, circuit, or whatever you have and we can see if it prompts any ideas on this end.

     Regards, Thomas

    PA - Linear Applications Engineering

  • 0 in reply to Thomas Kuehl
    Prodigy 60 points


    Hopefully these can help! its an old suppressor/expandor

  • 0 in reply to George Ellias
    TI__Guru* 93105 points

    Hi George,

    The images aren't really providing any clues. I've sent a message to an applications colleague in one of TI's audio groups asking if they might have some ideas about a TI compandor. If they come back with something I'll post it here.

    Regards, Thomas

    PA - Linear Applications Engineering