DIY Project Recommendations

pflouret · 2023-08-02T20:52:08.506Z

Sounds like your typical xy thingy with steppers would be one way, commonly used for cnc machines and plotters. They’re not usually super quiet tho.

Something like DIY PCB Ink Plotter using Arduino and GRBL CNC - Make PCB at home in few hours - YouTube

Other ideas would be to design something with gears, or rails with bearings.

Or a robotic arm, if you want overkill 3D Printed Robot Arm by GearDownForWhat? - YouTube

ciso · 2023-08-02T22:22:26.860Z

gogurt:

I’m curious for those that have done the Erica EDU series if there are certain modules from the whole line that are particularly helpful or educational. Any general advice would be great!

Late to the party here, but I’ve built a few of the EDU series, and honestly I’ve enjoyed all of them so far. I’ve built the VCO, VCF, Sequencer (x2 because I thought they were cool), S&H/Noise, and Dual VCA. I have the kits for the Envelope, Fold, and Mixer still. (Note: since your post mki x es has released an EDU compressor module as well.) I just haven’t had time lately to do the rest. I found them all to be fun builds, and while the Envelope is not quite an ADSR, I thought that learning about those limitations and how to work within them even with their quirks was cool.

I read the manuals for each a few times, skipped the breadboarding for the most part, but I feel I still got the knowledge even without the breadboarding. I did take a few bits and experimented a bit.

The only problem I had with any of the builds so far was that the TL072 chip was bad in my S&H/Noise kit, so I ordered a handful and stole one from the Env kit in the meantime. With the info I learned from the manuals I was able to confirm on the breadboard that it was the chip that was bad.

I’ve built a few Befaco kits, and they can be pretty tight. The STmix in particular is especially packed. I actually have that one out of my rack right now because one of the stereo pots that came with it was faulty, it’s going to be a bit of a pain to swap that out. The BF-22 Filter was a long, but fairly easy, build.

Another kit I would recommend is the 4MS RCD. It’s a little tricky with the LEDs but actually I watched as my 8 year old daughter soldered most of it for me. Radio Music was an easy one, but no longer available…but someone told me later this year there will be a new revision.

AI Synthesis makes good kits too. I built his Looping ADSR earlier this year, but stupid me didn’t read the manual at all, just built it, and I thought there was a problem with it. Turns out it’s one of those “quirks” that gives the module character. Abe responded to my email promptly and told me what’s up, overall great experience. I want to get my hands on one of those stereo matrix mixers soonish.

Hope this was more helpful than ramble.

Rodrigo · 2023-08-02T22:44:48.954Z

pflouret:

Sounds like your typical xy thingy with steppers would be one way, commonly used for cnc machines and plotters. They’re not usually super quiet tho.

Something like DIY PCB Ink Plotter using Arduino and GRBL CNC - Make PCB at home in few hours - YouTube

I did think something like this, but having a full XY gantry-type thing would end up obfuscating that part of the drum. Hence thinking about something that had a kind of telescoping movement or something where it only partially obfuscates the drum, and only when in use. I don’t really know movements and mechanisms though.

pflouret:

Other ideas would be to design something with gears, or rails with bearings.

Or a robotic arm, if you want overkill 3D Printed Robot Arm by GearDownForWhat? - YouTube

Something like this would be amazing, but I imagine will be 100% cost prohibitive. Most I saw are pretty big too (relatively) as they are intended for (at smallest) camera usage, which needs to support and move a fair amount of weight.

I did find something like this, which looks like an ideal size (and pretty quiet), but probably super expensive (and out of my technical capabilities to build).

duskatheghost · 2023-08-02T23:26:24.420Z

Hey Rodrigo, you might consider looking at SCARA gantry. It might be more out of the way of your drum and there are 3d printed examples

Google search SCARA

joegencorp · 2023-08-02T23:27:53.665Z

Have you considered placing several piezos in strategic positions and mixing between them?

Rodrigo · 2023-08-02T23:43:16.742Z

duskatheghost:

Hey Rodrigo, you might consider looking at SCARA gantry. It might be more out of the way of your drum and there are 3d printed examples

Interesting. I’ll have a look at this with a more woken up brain tomorrow!

joegencorp:

Have you considered placing several piezos in strategic positions and mixing between them?

I’ve actually been down an ambisonic mic rabbit hole today for similar reasons. With a decent-looking DIY build from Sound Sleuth. I still don’t know if what I’m wanting to do is possible in ambisonics (a kind of “reverse ambisonics” I guess?) where I have a mono output, but dynamically change the “position” and pickup pattern from the virtual mic. I did find a snippet from a vid that kind of shows what I think, but again, don’t know if the A->B format decoding and related stuff can happen in realtime (no additional latency) as that’s crucial for feedback-based things.

JaggedNZ · 2023-08-03T08:07:12.526Z

I’d suggest staying away from stepper motors and servo motors as the step or feedback frequencies and likely to overlap with audio frequencies.

You likely want small motors connected to large gears, I’ve build a drawing machine out of legos similar to thishttps://youtu.be/LZYr646Ul4Q or an example in cardboard https://youtu.be/y0HiDOBzKvs
Lego / gear motors tend to be loud though, but you might find it easy to prototype with.

Rodrigo · 2023-08-03T13:02:16.292Z

duskatheghost:

Hey Rodrigo, you might consider looking at SCARA gantry. It might be more out of the way of your drum and there are 3d printed examples

Ok, so having a proper look and it looks like SCARA could be a good way to go. And I guess lots of variants too (single arm, multiple arms, etc…). And with being 3d printer adjacent, there should be loads of kits, mods, etc… to getting something going.

Will investigate the ambisonics things first as if that can do a similar thing but in a static way, that would be something to start off with. Then if that seems fruitful I can explore “analog” movement with an arm.

JaggedNZ:

I’d suggest staying away from stepper motors and servo motors as the step or feedback frequencies and likely to overlap with audio frequencies.

Yeah. Even with “silent steppers” in my 3d printer, there’s still a high-pitched-ish sound that would get in the way.

I do like the plotter/drawing angle to explore too as there’s quite a few things for that out there too.

eequeue · 2023-08-03T17:07:26.454Z

I built two of the Polivox VCFs (well, one and 3/4; I’m still waiting on some jacks which I somehow ran out of).

The build was pretty straightforward ftmp and other than the Op Amps the parts were easily sourceable although some of the resistors were odd values I didn’t have on hand.

Would recommend. I think I’ll give the Envelope Generator a go at some point as well.

ciso · 2023-08-03T17:21:17.478Z

I wish the swamp was still available as a DIY. I would love to build one.

(Erica Synths, are you listening?)

hermbot · 2023-08-03T17:51:31.072Z

It’s not nearly as convenient as just buying a kit, but they did open source all the DIY projects: GitHub - erica-synths/diy-eurorack: Erica Synths DIY Eurorack Modules

ciso · 2023-08-03T17:52:52.218Z

I went to a PCB manufacturing site once. I had no idea what was going on. Too many options, and I don’t know which are actually important.

eequeue · 2023-08-03T22:36:35.057Z

I used OSHPark; I just uploaded the Gerber files and had PCBs in my mailbox in a couple of weeks. If you’re in North America it’s a good option, though more expensive than other places.

Give it a shot!

joshhh · 2023-08-04T13:46:04.054Z

feel free to ask questions if you are confused! most of the time you can just use the default settings from the various production companies

ciso · 2023-08-04T13:54:15.264Z

Ok, I’ll give it a shot when I have a chance…hopefully in a few weeks I’ll have a bit of a lull in work

eequeue · 2023-09-08T17:52:41.916Z

I wanted to share further results from the Erica DIY line.

I finished the second Polivox VCF. First is on the left, second is on the right:

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I had a couple of mix ups with these: I mixed up the frequency and volume pots so I’ll have to desolder them and switch them around at some point.

On the second one I wasn’t paying enough attention and got the TL072 chip reversed which through a series of unfortunate events which I won’t relate, I messed up one of my cases.

Other than some small aesthetic issues I still have I think they look okay and sound great. It’s quite a wild sound you get out of the K140UD12s. Worth the cost of getting them from Erica imo.

I also built an Envelope Generator from the same series. I got face plates along with the PCBs from JLC this time. Other than forgetting to have the order number removed I’m quite happy with how they tuned out, although I don’t love the font used on these, but that’s quite minor and nothing a bit of spraypaint (or similar)couldn’t fix.

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The PCB is quite crowded on this one so you need to be very careful about the build order. Particularly the LEDs, which are in rather crowded areas on the PCB. I have 4 more of these to build so I’m going to try varying the build order to make it less stressful.

Overall this wasn’t bad; the parts are easy to come by and the documentation is pretty good. Probably not for beginners but manageable for someone like me with a few build under his belt.

Last but not least, I built a Kosmo Twin T drummer module which wasnt too bad but took me about 3 hours in total.

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Not a hard build, just a bit finicky, as you have to install and remove the front plate a couple of times during the build. Also there’s no build guide or video like there are for most of his other modules. Not to mention, this is based on the RCA 4011 chip but specifically for the 4011AE version. There seems to be a decent amount of those floating around so not a big issue getting it.

tl;dr they were all challenging to some degree but well worth a go.

Jfkimmedy · 2024-02-21T09:21:22.057Z

Anyone got a recommendation for a cheap small audio amplifier? Want to experiment with an exciter and a metalsheet.

monopole · 2024-02-21T10:28:34.464Z

Adafruit has a few boards that require very little to have them working.

driedstr · 2024-02-21T14:25:57.061Z

Lepai LP-2020TI is cheap and cheerful. Depending on the volume you need, you might not need an amp tho, headphone outputs can drive exciters a decent amount.

barnaby · 2024-02-21T16:08:07.835Z

I somehow missed this so perhaps you came up with a good solution already, but your design questions never fail to nerd-snipe me, so here’s how I’d approach it:

Make an attachment with a pivoting arm on the underside of the drum, which is pulled into one extreme position by a spring, and can be rotated around the drum by pulling on a cable.

This arm bends around the side of the drum and has an attachment on the top, with a tube or slide or something supporting a linear arm holding the microphone, again pulled by a spring into one extreme position and moved by pulling a cable.

Optionally, give both axes zero-contact endstops e.g. inductive or hall-effect, so the controller can home and detect when its reached the end of travel.

Route the cables and electrical wiring arbitrarily far away to an acoustically and electrically isolated box containing silent stepper motor drivers and a controller. Keeping the cable tension correct is the hard part here – perhaps with something similar to bike brake cables?

Here’s a rough sketch of what I mean – obviously this would need to be turned into a practical design in order to be buildable!

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