Sunday, December 8, 2013

MFOS Vocoder (updated)

As soon as i found about the Music from outer space new DIY analog vocoder, i knew that i have to build it. after all, how many DIY vocoder projects are there? and to get a nice analog one can be pricy.
good job mr wilson!
So here it is, about 1 month later , the board is stuffed and ready to be wired and tested.
i made a lot of silly resistors combinations in parallel and serial in order to get the right values (which i didn't have at the moment)... for some of the bands- i used these polystyrene caps i got in a bargain from Electronic Goldmine .
i'm also going to mod it with the band volume controls with these nice sliders i found.
i got a lot of ideas about this vocoder , like adding a chorus circuit to the output and also some ideas about the case. i'll be updating this post soon...

Some updates for this project:
i've been looking for a proper enclosure for this vocoder but i didn't want to build anything from scratch. So...... here it is :

The beautiful Sierra 415A, used to be a test equipment box of some sort. it has a great looks with knobs, switches and leds, plus a built in meter! it's built like a tank with great quality parts and i guess it used to be an expensive machine back in the days. i must admit i felt a bit bad to 'destroy' a nice working unit, but hey - at least it's getting to be used, again. 
These boxes are not so cheap, but i could find this unit in 60$ icl. shipping off eBay.
i think it is worth it if you want a nice ready made metal portable box. it also has this 'cassette' hatch
which fits exactly with my set of sliders. i thought this will come ready made with a bipolar power supply, it actually did but it was much more work to isolate this circuit from the main board then to make something simple by myself. so i ended up making my own power circuit.
It took some work to prepare the box, empty it from all the circuits and then fit the vocoder PCB and the sliders PCB, fit some new pots and wire (like hell) every point.  wiring sucks!
Ok, but after all - it's working !!!! tried it with the internal oscillator and it sounds FAT and amazing. nothing like i know from software or digital vocoders. much more beefy. the sliders are a MUST if you want to change the sound while you go.
i still have one problem with one chanell but it's probably a mistake i did somewhere...

I also have some spece to add pots/stuff/mods/circuits so i thought maybe ill add a nice stereo chorus circuit to the output, we'll see.
For the sliders pannel I'm going to order a laser cut white metal panel with a printed frequency value of each channel.

Here are some pics : (audio will follow soon).


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