Logic Noise Hack Chat

In this chat we'll be talking about the kinds of sounds you can make from logic chips. Let's make a chip tunes orchestra together!

Friday, June 1, 2018 12:00 pm PDT Local time zone:
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Elliot Williams will be hosting the Hack Chat on Friday, June 1, 2018 at noon PDT.

Time Zones got you down? Here's a handy time converter!


Of course you could just take a beautiful-sounding instrument and simply play the right notes. But that’s taking the easy way out. Instead, we'll talk about using basic logic ICs to build something musical or at least interestingly noisy, a tradition that’s as old as the 4000-series chips themselves. We'll look at a handful of Elliot's favorite algorithms and circuits for composing in solder, and if all goes well, “music” will emerge.

Sneak peek: Watch the Live Stream from Hackaday Belgrade where I gave a talk starting at 4:16:30.

Elliot Williams is Hackaday's Managing Editor. After spending eight great years in Washington DC teaching econometrics and working on inflation by day and running a hackerspace by night, Elliot handed in his badge, moved to Munich and started writing as a hacker. He's now living the dream: getting paid to read (and write) Hackaday.

  • Logic Noise Transcript

    Sophi Kravitz06/01/2018 at 20:00 0 comments

    Hello! If you're here for the Hack Chat, put your questions in the comments of this page:

    but this week, we'll be doing something a little different. Less questions, more listening


    Ted YapoJun-1 2:48 PM
    @ðeshipu forgot to mention you on that

    we'll start the chat a few minutes after the hour

    ðeshipuJun-1 2:49 PM
    I don't actually know the impedance of my speaker

    Ted YapoJun-1 2:49 PM
    that analysis also assumes a 5V supply

    ðeshipuJun-1 2:50 PM
    3.3V supply here

    Ted YapoJun-1 2:50 PM
    you should check.  a 64-ohm speaker won't be loud from that amp, most likely

    ðeshipuJun-1 2:50 PM
    I use this:

    ðeshipuJun-1 2:50 PM
    it's quite loud with that amp

    Ted YapoJun-1 2:51 PM
    is it a speaker or buzzer?

    ðeshipuJun-1 2:51 PM
    passive buzzer

    ðeshipuJun-1 2:51 PM
    so basically a speaker with non-linear response

    Ted YapoJun-1 2:52 PM
    3V/120mA looks like 25 ohms

    Frank BussJun-1 2:53 PM
    it says "electromagnetic", but looks like a piezo speaker

    ðeshipuJun-1 2:53 PM
    it's electronmagnetic

    ðeshipuJun-1 2:53 PM
    I disassembled a few

    Ted YapoJun-1 2:53 PM
    anyway, it looks like you need a sizeable fixed resistor on top of the pot, so the loading on the DAC should be fine

    ðeshipuJun-1 2:53 PM
    because they forgot to plug that hole before washing them after assembly, so they rusted inside

    Ted YapoJun-1 2:53 PM
    you may need to experiment with the resistor value

    Boian MitovJun-1 2:54 PM
    Hello everyone :-)

    Frank BussJun-1 2:54 PM
    can you hear something with like 200 Hz sine wave? I tried this with a piezo speaker, and it is basically silent at frequencies below 1 kHz

    Frank BussJun-1 2:55 PM
    the lower the more silent :-)

    AlexJun-1 2:55 PM

    HI Alex!

    Boian MitovJun-1 2:55 PM
    Well... isn't that exactly the way the sensitivity curve of the ear works?
    I mean for a fixed amplitude....
    Patrick DiJusto joined  the room.Jun-1 2:56 PM

    Frank BussJun-1 2:56 PM
    I can hear a magnetic speaker fine with the same amplitude

    Boian MitovJun-1 2:56 PM
    for low frequencies this is most likely too small amplitude to be able to hear

    Boian MitovJun-1 2:56 PM
    not sure then :-(

    WooDWorkeRJun-1 2:56 PM
    @Frank Buss iirc  lower freqencies need more power to be heard equaly loud then higher

    Boian MitovJun-1 2:57 PM
    what is the diameter of the magnetics ?

    @Elliot Williams welcome! we'll start in 7 minutes
    Robley Williams joined  the room.Jun-1 2:57 PM

    Boian MitovJun-1 2:57 PM
    It is also matter of how much air volume gets moved

    Frank BussJun-1 2:57 PM
    right, it is the piezo effect, acts like a capacitor, needs higher voltage for the same power

    ðeshipuJun-1 2:58 PM
    @Boian Mitov 3mm

    Boian MitovJun-1 2:58 PM
    3mm diameter of the magnetic...?

    Boian MitovJun-1 2:58 PM
    the membrane ?

    Boian MitovJun-1 2:59 PM
    Hello @Sophi Kravitz  :-)

    Elliot WilliamsJun-1 3:00 PM
    Hey all!  For fun, I'll be running a sound stream and taking requests (when feasible) as we go.

    Tune in to to hear along.

    !!!! EXCITING !!!! our first Hack Chat with sound

    Boian MitovJun-1 3:00 PM
    Cool! :-)

    let's start in about 4 minutes tho, give more people a chance to get here
    fresal joined  the room.Jun-1 3:00 PM

    Elliot WilliamsJun-1 3:00 PM
    See if you can crash my Icecast server!  :)


    this sounds great!

    Robley WilliamsJun-1 3:02 PM
    Cool melody!

    ðeshipuJun-1 3:03 PM

    Adam Vadala-RothJun-1 3:03 PM
    hello hello!!!

    ðeshipuJun-1 3:03 PM
    @Boian Mitov it looks like this inside (next to the switch) --^

    ðeshipuJun-1 3:03 PM
    after removing the case and the membrane

    Boian MitovJun-1 3:03 PM
    @ðeshipu Nice...! :-)

    Adam Vadala-RothJun-1 3:04 PM
    its synth time

    ðeshipuJun-1 3:04 PM
    that's the rusty one, of course

    ðeshipuJun-1 3:04 PM
    I made a photo to show the people in the fab

    Ted YapoJun-1 3:04 PM
    it's always synth time

    I's the OFFICIAL synth time

    ðeshipuJun-1 3:04 PM
    sorry, I'm shutting up...

    Read more »

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Frank Buss wrote 06/01/2018 at 16:20 point

What's the point of using logic ICs for sound synthesis, if you can do it all in even small microcontrollers, and much better?

  Are you sure? yes | no

AVR wrote 06/01/2018 at 16:43 point

A lot of folk in the synth community including myself prefer the sound of all analog synthesis, it just sounds bigger and better to me.

  Are you sure? yes | no

Frank Buss wrote 06/01/2018 at 16:51 point

I'm sure in a double blind test you wouldn't hear the difference.

  Are you sure? yes | no

Ted Yapo wrote 06/01/2018 at 17:30 point

Is it kind of like why use tubes when you can get less distortion with transistors?

  Are you sure? yes | no

AVR wrote 06/01/2018 at 18:37 point

yeah its really all about the difference ways you can connect modules and overdrive them to create different sounds. There is a reason KORG and MOOG are printing money right now.

  Are you sure? yes | no

Elliot Williams wrote 06/01/2018 at 18:41 point

Interactivity.  When your sounds have to be coded, the "what happens if" loop takes a very long time to come full circle.  Much of the time, especially with modular-style setups, feedback is so much more immediate with the physical devices.  And that makes it just that much more enjoyable/creative.

But I do both.  :)

  Are you sure? yes | no

Frank Buss wrote 06/01/2018 at 18:49 point

That's just bad programming. For example you can use an accumulator and a phase shift value, which can be modulated very immediately. Of course, you shouldn't do a for loop and only test at the end for user signal or modulation changes.

  Are you sure? yes | no

AVR wrote 06/01/2018 at 18:50 point

I am with you there!  On this topic I always think about how one of modules int he MOOG model D has more gain than it should but as a result there is a warm overdrive when that module drives another and they kept the mistake cause it sounded awesome! 

join The Synthesizer Freaks facebook group to learn why Analog is king!!! Or get one of the following:
Aturia Microbrute
Korg Monologue
Moog Mother32

  Are you sure? yes | no

smartalyx wrote 05/28/2018 at 17:26 point

Are there any items we should 'bring'?

  Are you sure? yes | no

Elliot Williams wrote 05/31/2018 at 19:41 point

Not really, but what the heck!  :)  

A breadboard, a few 100 k potentiometers (or a good supply of random resistors), 0.1 uF capacitors (and/or a range of 1 uF to 0.01 uF), diodes, jumper wires, and whatever logic chips you've got on hand?  

I put out a (huge?!) parts list at the end of this installment:  But that's more like everything you'd want for a lifetime of fun.

If you're just getting started, an inverter is a must.  40106 or 74xx14 will do you.  A 4093 NAND with schmitt trigger is just as good.   

  Are you sure? yes | no

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