I was looking at Aliexpress and looking for some interesting chips/modules and came across boards that look like these:
That is indeed an actual Dolby Compander chip! With two of these boards it would be possible to make interesting TAPE IN - CLIPPER - MODULATION - TAPE OUT - thingies without needing actual tape machines (and it would work with no latency!).
A simple diode clipper would simulate the tape clipping quite well. This schem from Headwize forum has a good diode clipper thing that should have tape-like sound (emphasis/deemphasis stages not needed anymore as Dolby IC does it):
And then the tape flutter/wow can be simulated with PT2399 vibrato circuit. Noise is not a problem as our compander chip will de-emphase the highs
I will probably take a better look at this after winter.
PS. Those Chinese module boards are about 6€ piece (+shipping). And the Aliexpress name goes something like " CXA1332 Tape Drive Tape Deck Dolby Audio Noise Reduction Board Module"
PPS. Do they even make these chips anymore or is it all NOS?
TLDR: Look at this quickly drawn picture.
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where in the final chain does the PT2399 Vibrato ckt board go? I got all the ali express
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It would probably work best after some overdrive/distortion circuit.
Using a FV-1 might work a bit for the modulation as it has less latency and is easier to set up for modulation (at least in stereo stuff).
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The chips seem to be either fake or chinese can’t make working layouts; the chips just pass the sound, switching NR does not work.
But anyways here is the gutshot:
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Ι would also be very suspect of the germanium 1N34A diodes that are sold for cheap from Chinese sellers. Most likely they are fakes (relabelled Schottky diodes).
Not “Chinese” but “dishonest”. There are plenty of very good and reputable Chinese manufacturers and sellers, and plenty of scams from USA and Europe. Try not to fall prey to racial stereotypes.
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Could have indeed worded my opinion better. I have had good luck with Ebay and Aliexpress cheap IC and board sellers. This is after all oldchip with limited information so it is understandable that there is a mistake with their board layouts. It just sucks that they sell them even though it does not work properly.
