#1480

this is wild! 20 charssss

1 Like
#1481

I have a question about an output mixer for the 2017 meng qi rollz-5+ board that is different than this design: https://pugix.com/synth/rollz-5-schematics/

Each of the 12 audio-generating circuits are connected to the left and right busses by an output resistor on the board. my plan was just to replace the resistor with 2 wires, which will go to this simple resistor/pot circuit – http://tinyurl.com/y32cpfsr

EDIT: actually the resistor would probably go after the pot not before but same concept

I understand that the pugix one is know as an op amp inverting summing amplifier circuit, but I’m having trouble finding/understanding the benefit over the passive circuit.

1 Like
#1482

The benefit of the inverting amplifier in this case is eliminating interaction between the modules. With resistance mixing the impedance for each module is changed when a mixing resistor (pot) changes.
https://sound-au.com/articles/audio-mixing.htm

2 Likes
Norns - Audio In/Out Specs?
#1483

the first sentence of that describes exactly my problem, thank you for the reference!

The mixing of a number of audio signals is such a common thing to do that one would expect the Net to be riddled with articles on how and why signals are mixed. There are plenty of circuits that show how it can be done, but very little that explains the benefits or drawbacks of any particular scheme.

1 Like
#1484

Rungling has an amazing effect on CV Roolz!!!

7 Likes
#1485

round two of yesterdays stuber patch.

7 Likes
#1486

Have you ever tried putting pots on all those variable resistors on the rungler? I was wondering if it would make it a lot more playable

1 Like
#1487

I have not but thats a damn good idea!!

1 Like
#1488

Here’s a very lo-fi, noisy home-made rollz and ultrasound filter journey I made the other night.

Whilst it’s quite rough, the sound passed through the reverb/delay and onto the cassette seems to have a raw sound with a lot of depth that I find inspiring, and reminiscent of musique concrete and other early noise/experimental electronic.

I’m finding the ciat lonbarde workflow incredibly inspiring and therapeutic. Hopefully one day I can play with a better put together version of these circuits than my own (or make a better one)!

6 Likes
#1489

Angry Fourses

5 Likes
#1490

Did anyone take an archive of the old Nabra-Users Yahoo Group?

It has been deleted now when Verizon deleted all the Yahoo Groups and it would be shame if all the information contained within it was lost to a corporate whim.

2 Likes
#1491

I would be super interested in this!!
I created a yahoo account to join recently just to find out it doesnt exist lol.

#1492

For anyone wondering what the ultrasound filter does to audio (that hasn’t already tried), here’s a clip of the ultrasound filter playing nicely with diy norns!

10 Likes
#1493

i love processing shitty old mp3s thrpugh them

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#1494

This is a really good idea! I’ll have to try that out.

1 Like
#1495

I’m curious about the “brown” nodes on the rolls as they relate to “damaging things”

the scope says that they are basically operating as a 0 to -6v pulse (at least even rolls by them self). you can of course start getting weird stuff when connecting them together but nothing seems to be wild voltage swings outside of the +/- 9v range.

I’m trying to figure out how to be able to interface them with my gerassic organ circuit. I understand that it can be “dangerous” to connect them to “fishy” gear, which I believe to be gear that doesn’t tolerate negative voltages in the -9 - +9 range. there may also be some weirdness trying to connect outputs to them? I’ve also read that they are “potentially high current” I honestly don’t know what that means and I can’t find out how that could damage things/what things it could damage…maybe this is the output-output concerning thing.

I hooked up one to my attenuverter in my eurorrack system (intellijel quadratt) to get it to be a positive pulse and it works fine to trigger the gate in on my gerassic organ then.

So basically I’ve figured out I think I want a full-wave rectifier on the input so that negative signal flips positive. I found this non-ideal (i.e. positive has an extra 2k impedance I think) 1 op-amp full-wave rectifier design and i put it in the simulation for my gate in and it seems like it will work fine.

http://tinyurl.com/y4jeaa5z

What I don’t understand is if this could cause problems. I’ve read some stuff from y’all @crucFX @barrford maybe one of y’all happen to know if what I’m planning is ok?

#1496

I have one more question to add onto jlmitch5’s: if I just use an attenuverter and not a dual wave rectifier, do you think I would be able to use the rollz a clock source for other gear like an sq1 or keystep?

#1497

The Gerrasic Organ uses a CD4067 chip. Looking at the datasheet, under “absolute maximum values”, it reads:
“Input voltage range, all inputs: -0.5V to VDD+0.5V”
VDD = 9V in your case, if running off a battery or 9V linear regulator.

So, don’t connect the negative going rolls to your Gerassic Organ inputs, it will fry the rare CD4067 chip.
A full wave rectifier would prevent this, or maybe an inverting op-amp buffer. (i.e. an op-amp buffer with gain of -1).
This is in effect what your attenuverter is doing.

To protect against the high current you can use a resistor (like you would for an LED). Standard eurorack output resistors are 100K.

2 Likes
#1498

ah yeah :+1:. if you look at that simulator I posted, the TP is the “out”…that is basically being used in place of the button in the circuit, it’s regulated by that XOR chip.

I’ve got a handful of adapters and the still stocked smd version of the 4067 which I’m using so I’m not too worried about frying it on this bread board, but I’m pretty sure I’m good there based on what I understand.

To protect against the high current you can use a resistor (like you would for an LED). Standard eurorack output resistors are 100K.

Ah okay cool. So I think this input impedance is the same as an “output resistor” in this case.

Screen Shot 2020-09-08 at 4.43.52 PM

I don’t quite understand how the opamp affects it, but I think the resistance is additive here. I believe the effective input impedance is either 101k or 102k depending on if it’s a positive signal or not.

#1499

^ Datasheet above

As @barrford mentions - you do not want to pop a 4067!

You can pull Positive rollz Pulses by adding a 10k Resistor to the Collector on one of the NPN’s to create a dc coupled output.

rollz positive
rollz positive722×698 195 KB

Here is a little guide ^

1 Like