I wonder what his code actually did, and if maybe he could have got a better result.
There was also this:
They were about to go mainstream when the CD happened.
For anyone who doesn't know about the EQ curve on records, it's basically a big bass cut and a big treble boost. Bass causes huge wobbles in the groove so it's cut, and treble is hard to pick up, so it's boosted. Then you just do the reverse on playback.
Also a good point that there's nothing on the Voyager record instructions about this...
Some of the world’s earliest disc recordings, dating from the late 1880’s, exist today only as pictures in books or magazines. The discs themselves were lost long ago, leaving little hope that their sounds could ever be heard again.
But sound media historian Patrick Feaster has developed a method for extracting sound from these prints, bringing to life rare audio content thought lost to history. Feaster, who works for the campus Media Preservation Initiative, discovered one such print in an 1890 German periodical housed in the stacks at Indiana University Bloomington’s Wells Library. It represents the oldest gramophone-type recording available anywhere for listening today — the earliest audible ancestor of all of the world’s vintage vinyl. By “playing” the inked spiral, we can again hear the voice of gramophone inventor Emile Berliner reciting the poem Der Handschuh by Friedrich Schiller.
It took forever to finish as I wasn't that skilled at the time and the number of switches and pots was simply beyond everything I had soldered before, but I managed to succeed it and spent some good evenings playing with its effects.
Is there any way to determine the values of the resistors and capacitors on the die based on their geometry, or would someone have to build up a standalone circuit and experiment until coming up with something that sounded similar? Can a person at least infer one value from another by the ratio of the geometries, like one resistor being 2x another if it were twice as long?
BTW, I built up a perfboard with this chip and a pile of resistors, capacitors, and potentiometers many moons ago. Just tore it down a short while ago. 76477 was also my Automated Teller Machine password for a lot of years.
Because resistances can vary 20% from chip to chip, analog circuits generally are designed so the ratio of two resistances controls things, rather than the absolute resistance. So you probably don't need to figure out the absolute resistance.
That's bad if you want white noise, but maybe the transients were put there intentionally? They could have a musical purpose.
EDIT: This is assuming the white noise generator resets for every sound. Is that the case?
Edit: And I wouldn't expect the situation to change soon. Accurate analog emulation is something commercial VST plugin makers have been working on for years, and they've come "close enough for most people", but the time spent on algorithm development and optimizing CPU usage is quite high.
From memory, the SPICE transistor models take things such as transistor feature sizes as parameters, so it might be possible to get a surprisingly accurate model from the die photo?
Of course these days you'd use a microprocessor to generate all of the sounds these could do. But it would still be fun to build the sound effects kit that RS use to sell.
The 76477 (http://www.vgmpf.com/Wiki/images/4/40/SN76477_-_Manual.pdf) has more pins and uses them to bring out more of the controls. The noise-clock in particular is controllable by anything that sinks its 'resistor' pin's current to ground, so a simple NPN sink driven by a slow sawtooth will smoothly vary the noise output from a 'tiktiktik' to a roar. The 76495 doesn't make that control available.
Can anyone here approximate the cost to re-produce this chip ten years ago? I mean, it's not very complex, but it is analog and it couldn't have been cheap. Maybe someone had to find a use for an old machine that had nothing to do anymore? That could explain it.
Considering the age of the chip, the masks are probably not even available in a digital format and the fab that made it had been shut down a long time ago. Recreating these processes is a massive undertaking that takes a lot of manpower.