#1297

Happy you enjoyed the episode and happy to answer your question (although it seems you’ve already figured it out): the module is Press by Softwire Synthesis which, as far as Eurorack companies go, is definitely under the radar, which is a huge shame, as Lance is amazingly prolific! So many amazing designs.

I’m a fan of the Ondes Martenot where Press got inspired from. It’s a simple idea, 6hp, one very pressure sensitive button, gate output, through output, two inputs, two outputs which can act as voltage or attenuation of the incoming signal. The voltage can be 5 or 10 V and you can set the two outputs to crossfade, so when one is high the other is low. I’ve been waiting for this design for what seems almost a year! I got #1 :smiley:

Since this is a CL thread, I wanted to say that I brought this up during the show mainly because I think it would sit well within a CL microcosm. The button is made out of wood (hey, that’s important) and the pressure is a good method to control Ieskul modules. Any questions, feel free to ask!

3 Likes
#1298

You know, as someone who loves sparkling water and bongos, that is completely okay. Maybe you have already integrated those impressions and they will click whenever you pick up the coco / plum back. Do record some bongo jams though, I would love to hear that!

1 Like
#1299

im gonna make a record comprised of piezo recordings of seltzer bubbles and bongo taps run through avdog aux into coco

8 Likes
#1300

run it into the piezo input on the coco and use it for a trigger too

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#1301

I am going through the meng qi rollz 5+ v4 (2017) pcb. and I’m confused about ground. It doesn’t seem like there are traces going to ground or the - terminal of the dc jack on the pcb. for example, the ground jack contact, as well as the dc jack outer contact don’t seem to be connected to each other (or to anything). maybe this is me just not understanding electronics…I thought everything needed to be connected to a common ground?

#1302

There may be a “ground plane” throughout the board, either comprising the negative space on a 2-layer board, or a separate internal layer of copper if it’s 4-layer. Do you have a picture?

2 Likes
#1303

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Here it is. There are definite independent traces on either side of the pcb. So maybe there’s an invisible layer in the middle which connects all the grounds together

1 Like
#1304

Tape marks output ie z resistors for anyone curious.

#1305

So if you compare the traces on top to the traces on bottom – you see that the top ones are just traces, but the bottom ones have a sort of separation, an outline, surrounding each. This leads me to believe that the negative space of the bottom layer serves as a “ground plane” for the whole board.

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#1306

ah okay, thanks for explaining that!

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#1307

Do you have a multimeter? You can check this by doing a continuity check between any two ground points.
If you don’t have one you can also connect anything that will give you a visual or sound signal between any two points on the board and verify that they are connected. An LED and a 3v lithium battery with a couple of wires will work.

2 Likes
#1308

Good point on the multimeter, I do have one that can do a continuity check, I’ll check with that.

One more question on this, I can’t find any SPST (ON/OFF switches) at Tayda, and I’m wondering If an SPDT ON/ON switch could be used in place. It looks like the circuit board connects:

A - Ground/negative terminal of DC jack
B - Center positive terminal of DC jack
C - Circuit

So I’m pretty sure A->B connection would be doing this:

Screen Shot 2020-07-05 at 1.21.30 PM

EDIT: actually upon google, it sounds like that is probably a bad idea, unless I’m misunderstanding the way the board is set up.

EDIT 2: wait, I’m wrong, a is connected to nothing I think, because if I look at the side of the pcb that has the ground plane, you can see a circle around the contact, which is isolating it from the ground plane. So I think this will be fine.

1 Like
#1309

You could also “beep out” the terminals on the board to see if A is connected to ground/power, to make sure you won’t be shorting anything out when the switch is in the “off” position. When in doubt, beep it out.

1 Like
#1310

since selling my PB2, I really miss the sound of the gongues and ultrasound. Would love a plumbutter mini with a pair of each, a pair of rollz, and nothing else. I can dream. :sparkles:

2 Likes
#1311

Do the schematics for these components exist? Could one theoretically be engineered?

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#1312

Based on what I’ve learned from figuring out this rollz-5 stuff:

Schematics for gong are here but might be slightly different than the paper circuit as the schematic is based on the meng qi board https://pugix.com/synth/rollz-5-schematics/. 3 roll schematic there too…transferable to any size roll, just add/substract a stage.

The paper circuit file for gong from the cl website gives a lot of info about variable parts and what they do to change the circuit.

You could buy pcbs from @mudlogger here for a couple rolls and gongs
https://llllllll.co/t/fs-ww-ciat-lonbarde-paper-circuits-pcbs/23342. Or you could bread board out the rollz and then do it on perfboard

The parts for the rolls and gongs are simple and cheap. You could get it all from tayda which is pretty simple to search through. You’d probably want to do even rolls only, odd rolls are more for the ultrasounds.

You could do some interesting stuff with a switch (or socket) for the roll caps to get different speeds of the rolls. And use a dual gang pot for the x values to get controllable pitch on the gongs like the pugix page mentions.

All in all this would be a pretty doable project for a beginner I’d think if you are willing to dive in and figure out the puzzle that is these circuits. Been doing it for like a month with little electronics knowledge going in, it’s fun

8 Likes
#1313

what a generous post, thank you so much for this. I’ve been looking for an excuse to dive into learning electronics/synth-repair/DIY more seriously, this might be the perfect in.

3 Likes
#1314

no prob, two more helpful things to get you started.

Legend for the part symbols on the paper circuits in this post Mobenthey/Ciat-Lonbarde (synthmall) thread

And from @mlogger a way to wire a switch with multiple capacitor values for the hairy capacitors.

65D6408C-0F1C-4652-A3D1-272608A02BEC
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5 Likes
#1315

it’s how i started! worth the effort

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#1316

I’m building a box of 4 gongs and 4 ultrasound filters right now (can’t afford a plumbutter and already built a mini-rolzer), its quite easy to do so if you go with manufactured PCBs, I find it way more tedious to build them on paper.
I have to troubleshoot 1 ultrasound as the pot is constantly burning, need to figure what’s wrong. Then wire all gongs, choose capacitors values, and it will be done :slight_smile:

For the Gongs, schematics from original paper circuits and Meng-Qi version (on pugix’s website) are a bit different but you can mod them easily to add auxiliary inputs (like on PB), I’m also adding vactrols for CV Frequency input. I can share my building notes when it’s finished and completely working.

If you want CV control verso/inverso style, you might look at the Esoterica Spikering, it’s quite similar to the Gongs (pinged filter, without pulse delay but with cv controlled FM) and you can build them with a switch for Trad/Gonzo modes. Theres an added pulse generator normalized to the filter pulse but you can add a switch to break that connection and use both parts of the circuit independently. I made one recently but still have to work a bit on it and adjust values.

5 Likes