Anyone ever build one? I just finished a stripboard layout. Built it and it seems to be working, though I seem to be getting a bit of modulation somewhere? Is this normal?
Pretty cool sounding module.
No Sequence
With Sequence. Modulation not as noticeable.
Link:
http://www.bartonmusicalcircuits.com/4046/
Looks interesting, your version has four frequencies? (Original has 7.) Itād be interesting to have outputs for each frequency separately, then feed them into a VCA mixer to mix them under voltage control.
Edit to add: I just realized since this thing generates square waves, could you use an analog switch as a VCA? Maybe not a MAX313 but maybe a DG412? Actually two. Thatād give the same functionality but with voltage control, or at least Iām guessing itād work. Others would know better.
Aw this thing looks awesome!
Sweeping this in some geometric way could be really cool
I just added 4 for testing. It will have all 7 divisionsā¦ Thereās a few ideas for mods I have rolling around. If anyone is interested in the stripboard layout, Iāll post it once I can verify it is all working correctly.
Could the āmodulationā you refer to be caused by occasional double triggering in the square wave converter? Iām looking at the schematic and I see this comparator:
This is not dissimilar to the input stage on Bartonās drum modules, with a threshold of ~0.12V. If I try to trigger my drum modules directly from my KeyStep it triggers on both gate on and gate off; I donāt have a good enough scope to try to diagnose that, but my guess is thereās some ringing on gate off that causes it to retrigger. What waveform are you putting in? I know for instance the 3340 pulse wave has seen some ringing problems.
That threshold seems kind of low for the drum modulesā gate to trigger conversion to me. For square wave conversion things are different, you probably donāt want too high an input. Still, maybe increasing that 1k resistor is an experiment worth doing to see if it affects your āmodulationā. I dunno, just a guess and maybe not all that likely.
That kinda makes sense! I may give it a whirl to see if it makes a difference. Thanks!
Iām wondering if itād make sense to use the input stage of Carmello Azzarelloās sub oscillator instead. Supposedly he did work hard on making it work well with a variety of input waveforms.
(Not that Iāve used it myself.)
I made his Sub oscillator. It works well! I havenāt noticed the modulation on other demo videos, thatās why Iām guessing maybe I botched something? Iāve been sending various triangle,saw, and square waves at it. Seems to be the same with all.
Quite noticeable here.
Are there any filters on this thing that could be introducing that modulation frequency? One thing to notice is the rate of the modulation is consistent even with the changes of the divisions.
It sounds like interference, or something in the power. If itās static as you say thatās where Iād start. Try a temporary shield/cage (aka tin) or with battery power.
Hereās my Stripboard layout. I was a bit confused by the power supply schematic. Maybe I did something silly?
You donāt need C10 and C12 near the power header. You do appear to have bypass capacitors near all your ICs on the power pins, and thatās good. Bypass capacitors are shown in the schematic close to the power header but on the board thatās not where they go.
Barton always specifies 10nF for bypass capacitors but almost everyone else uses and recommends 100nF.
Other than that I donāt see any power issues. But what are you using for a supply and how does it get to the board?
Bartonās PCB has 10 nF capacitors both near the ICs and near the power header (also on the unused ā12 V rail). no it doesnāt, see below.
Really? In the schematic there are only four bypass capacitors, all in the power section on the lower left: one for the 4046N, one for the 4040N, and two for the dual op amp (which does use -12V).
No, youāre right ā I thought it was a single supply opamp, but the supply lines for that one are nicely hidden among the caps.
Cool. Iāl take em out. Iām using a standard eurorack cable from a Tip Top power supply. Case power is good for sure!
*took caps out. No changeā
Here it is complete except gotta figure out the strange issue. Issue or not, itās still very neat sounding.
I talked with Michael Barton. He seems to think itās interference from another module in my case. Iāve been using it a lot, and to be honest, doesnāt bother me a bit. Iāll post my layout in the Verified Stripboard Layout thread if anyone wants to give it a go.
I want to experiment with making a voltage controlled version. Should be easy impossible interesting.
