…I have my first live performance with my synth on Saturday and I am very close to a crisis… I thought that I will at least add a drone to my synth to have something in the background running if I mess up: so to say a backup solution which works on its own.
Well, so far so good. I thought I go easy and recreate the Circle Drone of Doom but I only have transistors which oscillate above 12V and it’s a nightmare to get the voltage divider resistors set up, so that it works reliable (I also lack 10k pots ) anyways, after struggling for like 4 hours, I decided to go with the good old 40106 square wave oscillator.
…an then the next problems occurred: whatever I do to mix the 6 oscillators together, the sound is not really clean. I hear blibs and blops here and there and the more channels I turn on, the more chaotic it gets, even if I tune nice octaves or thirds or whatever. The circuit is fairly simple, so I am missing something obvious I guesss: how do I get better sound/mixing quality out of this? In the oscilloscope I see quite sharp rises. I tried adding filter caps parallel to R13 but I did not notice a difference.
I lowered the threshold for the 40106, so that it’s fed with 0V to e.g. +6V, then do the AC coupling and mixing them together with a TL072. This way I at least avoid clipping (so that the voltages do not max out the rails), however, I don’t get a nice clean sound when I compare it to this guy’s 40106 drone:
He uses a buffer before for each channel before the mixer, so I guess that’s what I try next. There is still room on the stripboard to add another 40106 and I use those as buffer (just like he did with 3 oscillators and three inverters as buffers), picture taken from https://drive.google.com/file/d/1WVMXd86SbJjbxJNew_jMWu3IVeoduifs/view:
That’s the recommendation I’ve seen too. Don’t know if that’s the issue but if it is the solution’s simple, use two 40106 with half the gates on each grounded.
Just throwing ideas out here, but you can make a charge pump with a 40106 and a handful of caps/diodes. You could boost your 12V to 36V or higher! Not sure you’d get enough current to drive the six oscillators, but I reckon it’d be fun to try.
I saw this trick in a valve distortion pedal I built that runs off 9V put provides a much higher voltage to the plate of the tube:
Yes that’s true, I even used -12V to +12V, to get 24V which was more than enough. It was just my brain which was too tired to figure out the correct set of resistors and since everything affects everything else in that system, it was not doable for me (now I am running out of time either). Also CircuitJS fails to simulate the reverse avalanche mode of the transistor so I could not go the lazy way and click around the GUI
@analogoutput I just grounded 3 of the gates of the 40106 and indeed it sounds much nicer, thanks so far!
I’ll now fiddle in the buffers, not sure if those make things noticeable though…
OK, I ended up with this. Reused the three unused pots to do the volume of each channel individually. It sounds much much better now but there are still frequency combinations where the oscillators lock together. I don’t fully understand why since they should be uncoupled. Maybe even more crosstalk although I am using the remaining three gates as buffer.
With the 40106 there some fun sync to do, like in this old thing i’ve made
sync option is playable in this vid with the big center knob (sort of a filter fx)
just a pot and one diode to add, very simple
in my VCO bank module with a 40106 I added a switch to have the syncro
I thought that I will at least add a drone to my synth to have something in the background running if I mess up: so to say a backup solution which works on its own.
) anyways, after struggling for like 4 hours, I decided to go with the good old 40106 square wave oscillator.
)!
