Gallery, Projects and General > Project Logs
Extending the soundscape of a hexaphonic guitar pickup
sorveltaja:
Today, I restored the original resistor values(R7, R6 and R27) for the Lfo, because I had completely forgotten to test, how changing the resistors, that are in parallel with Ldr's, affect their range.
But nothing usable came up with that, so the original resistor values(R33 - R36) remain the same(470k).
I haven't yet found a simple alternative triangle/sine lfo, that has an adjustable bias in it. So that must be one of the tough ones to implement, as the ones I've found so far, are way too complex.
The base circuit of the phase shifter works as it should, except the Lfo section. After all, the device could still be used as it is, even though being 'lacklustre'. But we'll see.
Different approach for an alternative Lfo could be to try and make one, that is electromechanical, like a pair of led/ldr, that has a rotating disc(with holes/patterns) between them.
Not sure, how the most usable, 'effective range' could be achieved by using contraption like that, though.
But the involved factors(like motor speed, brightness of the led) should be a lot more easier to comprehend(at least for me), than using only electronic components.
sorveltaja:
So, after quite a long hickup, it's time to get back to the project. The phase shifter, that I was working with back in the april, is still at the same stage. It should be usable, but still needs some tweaking and testing.
As there was period of weeks, when my ability to concentrate was practically lost, this is also an attempt to get the 'mojo' back.
To get my feet wet again, there is that vocoder-thingy. I already have all the needed components in my shelf, plus the pcb's are also etched, drilled, and ready to go:
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Probably not the most simplest project, as there is also a 'clarifier mod' for that vocoder involved. But what the heck, I'll give it a shot.
The hex pickup system was removed from that guitar, to get room for the ordinary guitar humbucker pickup. But I'm quite sure, that it's just temporary, as that hex pickup system has that specific sound, that I'm after.
But after all, it's just a matter of having a dedicated guitar for it. As a matter of fact, that guitar was hacked together from bits and pieces, so it isn't necessarily the most playable one, but for now, it's adequate enough for that purpose.
As an off topic ramble, I might order my first ever decent electric guitar, once I get the tax return next month. If that goes, as expected, the old carcass has the hex pickup system installed back in it permanently.
sorveltaja:
The vocoder pcb's are almost populated:
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Between the boards is a two-sided, printed 'clip', that holds them nice and tight together. It could well be a permanent holder(probably needs to be extended on both ends, to have holes for screws).
Also it takes the strain off the to-be-soldered connecting wires, making the boards a lot easier to handle together, when the outboard wiring mayhem hassle begins.
Once all wiring is done, and all goes as expected, plan is to stack two pairs of the boards, to make the whole pcb footprint narrower. When all 5 boards are placed one after another, the cumulative width is just too excessive, being about 550mm.
sorveltaja:
Wiring hassle before and after, using rather hi-tech building platform:
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I have omitted some switches and plugs(right channel and effect loop), as they might not be necessary in testing phase. Lots of unshielded wires running around, so we'll see if the noise becomes a problem.
Currently I don't have enough shielded cable for all the wiring, so only audio plug wires are shielded.
Next I'm planning to draw and print some kind of gadget, that makes bending the IC legs hopefully easier. When the IC is new, the legs are usually spread out too much to be pressed to the socket.
Bending and aligning the legs one by one is just pain in the arse to do, especially, if there are more than one IC involved.
After that, I think it could be time press the IC's into the sockets. That is always preferably done only after all the soldering is done, but in this case, none of the IC's (4136 quad op-amps, 571 companders, and one single op-amp) are cmos-based, which could be very sensitive to static electricity.
As mentioned before, there is a mod, that clarifies the overall operation of this vocoder(buffering the input level pots). It adds even more wires, and althoug there are simple and clear instructions, first I have to get my head around, of how to connect it to the main circuitry.
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Warning: babbling ahead.
As usual, when building this kind of lengthy project, there are always times, when I think that "why bother, buy something commercial instead, that works right away".
One example of it is a stomp-box size Boss VO-1 Vocoder, under 200 euros, that seems to do all the tricks and even more(based on youtube videos about it).
I have a sneaky suspicion, that it(and also other ones in that price range) is based on dsp(digital signal processing) technology. So its behaviour is pre-programmed, and can hardly be altered.
What comes to commercial analog vocoders(stand-alone units, not the keyboard-embedded ones), they tend to be bloody expensive(if one can find/afford one these days). At least I would never dare to modify anything like that.
But again, this is about analog signal processing, as it has some... quite different aspects/dimensions in it.
Most lamest example, that I can think of, was back in the 90's, when I had a cheapo start-o-caster(my first guitar, now long gone), and Dunlop's Cry Baby wah pedal. Yes, expected sounds were there.
For some unknown reason, I decided to connect the cables in reverse/backwards to the wah pedal. Of course, there was no direct guitar output, but instead bird-like sounds, depending of the guitars volume/tone settings/wah pedal position.
That very same effect can be heard on one of the Jimi Hendrix's Electric Ladyland track. I don't claim to have enough intelligence/creativity to find that effect; it was pure coincidence.
Sea.dog:
When I played with ICs I used to grip the end of the package and press the legs onto the bench thereby straightening all of legs on one side. The alternative is to make a carrier that you press the IC into, package first, which closes the legs. You can then use it to position the IC over socket and then press it in. I'm enjoying this build and understand exactly why you want to build it rather than buy a ready made product that doesn't have the flexibility that you can add to yours. In addition, the satisfaction you'll fell when it's finished can't be bought.
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