DRUMMACHINE & SEQUENCER

[VanaVara]

Hi guys!
I have a couple of noob questions for you, maybe you can help me out?:)
I'm having hard times understanding all the stuff about CV/Gate, Triggering, Internal Clocks / External Clocks:
How could one connect, let say, drum modules (like these: http://ericarcher.net/devices/tr808-clone/ ) to a sequencer so i could get a drum/rhythm machine, or how to connect the oscillator/noisemachine to a sequencer?

What i would like to build is:
• Kick+Snare+Hihats ---> Sequencer(s) = Drummachine
• OCS (sin/tri/saw) ---> ADRS ---> Sequencer = Melodymachine :)

Are these machines possible to build and how, or maybe there's something essential i don't understand...?
Maybe you can help me out with theoretical background in layman's terms and some schematics/layouts?

Any help is very appreciated!
Thank you in advance:)

[-minus-]

Hi again,

Quite a few questions. I'll try answer them, but there are others here who are far more knowledgeable than me!

The GATE thing is kind of like what it implies. It's like opening a real gate for a period of time, letting something through the gate, then closing it... but in our case, it's not farm animals passing through the gate, it's electricity! It's sort of like holding your finger on a button for a while then releasing it.

The TRIGGER on the other hand is sort of like pulling a trigger on a gun. It's a very quick thing! It's used to switch on other things like drum modules for example.

The CV is a control voltage. So if you have a VCO (voltage controlled oscillator), by sending it some voltage, you can control the pitch for example.

I think your best bet is not to get too advanced right now. I'm not sure how much you know. Before you go creating more complex drum modules, I'd suggest you look at something simpler. Have a look at Eric Archer's Mini Space Rocker circuit:

http://ericarcher.net/devices/mini-space-rockers/

I have built this on stripboard some time ago and it works well. You can trigger it manually with a momentary switch or with a simple sequencer like the Baby 10.

The Baby 10 is quite simple to make. It is based around a decade counter, the 4017 chip. It is basically a chip which has ten outputs which switch on and off in sequence from one to 10. These 10 outputs (gates) are sending voltage out which can be individually adjusted if sent through potentiometers. These voltages can then be sent to a VCO which will produce a series of tones. You could find Baby 10 circuits easily. The 4017 needs a clock of some sort. Often it is a square wave oscillator built from a 555 chip running at a low frequency. This would then be what is considered an INTERNAL clock. The 4017 could be fed a clock from another separate module. This would then be an EXTERNAL clock.

A simple VCO to hook up to a Baby 10 might be the Slacker 4046 VCO:

http://srv2.electro-music.com/forum/topic-33607.html&postorder=asc

You wont need all the resistors going to pin9. Just feed CV directly.

I would recommend heading over to the Lunetta forum and looking at that stuff. Loads of ideas there! Hope this has helped you more than it has confused me!

[emdot_ambient]

Building a dedicated drum machine is actually a bit more complicated than building the melody machine you mention. Each drum sound is essentially going to be its own circuit (or module). That's easy enough. But to bring them together as one device, the sequencer you use is going to have to trigger each of the circuits independently. So if you're thinking a 16 step sequencer, you'd have to have a trigger for EACH drum voice for EACH step. (3 drum voices and 16 steps would mean 3 triggers per step, or 48 switches total.)

That can be done off one sequencer, but it's actually not a format that's widely available in the DIY land. Most sequencers out there are limited to 8 steps and one Gate per step.

Note that Gate and Trigger are often used as interchangeable terms. Some modules are able to use both. Some require a true trigger, which is just a very fast spiking voltage as opposed to the on-for-a-while, off-for-a-while nature of gates. You can easily convert a gate output to a trigger, though.

So, for a drum sequencer, you'll need to look for a "Trigger Sequencer" that has one trigger line per drum voice you want to use.

As for your melody machine...there are tons of options out there for that. Take a look in this forum for the SympleSEQ thread. That's about as easy and basic a sequencer option as you'll find: 8 steps per sequencer, one CV and one Gate output.

The basic patch for hooking that up to make melodies would be:

CV output of the sequencer to the Pitch input (often called V/Oct) of your oscillator, and possibly to the Frequency In of a VCF (Voltage Controlled Filter).

Gate output of the sequencer would go to the Gate In of your envelope generator (ADSR).

CV out of the ADSR would go to a VCA (Votage Controlled Amplifier...don't forget this part!), and possibly to the Frequency In of a filter as well.

Oscillator wave out (sine/tri/saw) goes to the In of a filter (it'll sound pretty dull otherwise).

Filter output goes to the audio in of the VCA.

VCA Out goes to your mixer or FX unit (sound output).

So if you look at it in 3 parts (Audio, CV and Gate), it goes like this:

AUDIO
VCO =>VCF=>VCA=>Out to whatever

CV
SEQ=>VCO
SEQ=>VCF (optional)
ADSR=>VCA

GATE
SEQ=>ADSR
SEQ=>VCF (optional)

...and, of course, this is not the only possible or worthwhile signal path. Both CV and Gates can also be used to control VCAs, for example.

[VanaVara]

Guys, you are amazing!:)
Thank you so much for a comprehensive explanation, it surpassed all my expectations!
Yesterday i finally completed APC+4017Sequencer (at first it didn't work because i forgot the jumpers under the chips), but as i expected it has the problem with sequencer pots as Minus already wrote --- they are "mute" 2/3 the way round, so it leaves me with very narrow range of pitch change. So now i'm thinking is it the problem with sequencer or the whole circuit? Maybe if i'd build 4017 Sequencer as stand alone with CV out, and connect it to APC with CV in, or whatever VCO, the problems would disappear?

[emdot_ambient]

Well, as I mentioned before, the SympleSEQ thread in this very forum has probably the easiest build for an 8-step sequencer: http://electro-music.com/forum/topic-49287.html

[VanaVara]

[-minus-]

A Baby 10 is a very simple sequencer. You don't need a kit to make one.

You can control multiple drum modules from the one 4017 IC, so you don't need multiple IC's running from one common clock. Just feed the outputs of the 4017 through a diode, to a switch so you can turn the beats OFF/ON. You can run multiple diodes and switches from each of the 10 steps, or however many you chose to use.

To get a narrower 'trigger' signal, use a AND gate and feed it with the output of a step AND the clock. Inverting the clock signal first will give you a narrower clock pulse too.

[RF]

I've been pleased with the use of Lunetta-Type circuits for triggering drums - using just very simple counters, shift registers and dividers to create unique drum patterns...

Here's what I did for the QuadBass++ with simple Logic.
http://www.sdiy.org/rfeng/quad.html

As minus suggests - take a look at the Lunetta forum for how to use these.

bruce

[VanaVara]

Hi again!

[bikini-inspector]

nice choice! APC+WSGfilter are pretty much what i did and it sounds great!

no need for a drawing: the output of the APC goes to the INPUT of the filter (blue wire in my layout).
the black wire from the apc's output goes to GND of the filter.

or, you could wire up input and output jacks to the filter to keep the possibility for use with other gear.

Funny, this afternoon i added a 1/4 jack to my box to do just that

i like your thinking with the sequencer: several BUSes to control several voices!

[VanaVara]

[bikini-inspector]

hi

usually, in 9V circuits like these, only one wire is drawn. This is because when you wire up a jack, the second wire is always ground. (if not, you will be told)

It doesn't really matter where you take that ground from, it can be the battery or some place on the circuit board.


same goes for connections without jacks, but when you power 2 circuits from the same battery, the grounds ARE already connected (via the battery), so you would just have to wire up the signal wire.

i've added jacks to your drawing using the bottom row of the stripboard. As you can see, there is plenty of room for ground connections.

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[defog]

Not to overly complicate things, but you could also make a very simple drum triggering device with an Arduino. You'd be able to trigger drum modules via midi notes fairly easily, unless you want a traditional-style sequencer. I have examples and code if you're interested.

[Cynosure]

Defog - I am interested in that. If I can make it give 5V trigger pulses then it could drive the circuits i made for me drum machine. Please share.

[bikini-inspector]

diddely-ditto!

seems like a convenient way to back up the weak monotribe drums with diy modules.

[VanaVara]

Thanx, bikini-inspector! Yesterday I build APC+WSG and it's working like a charm!
Now i would like to integrate LFO to this circiut to modulate APC
I found this simple LFO layout: http://electro-music.com/forum/topic-30456.html
My question is --- how to connect this LFO to APC? Where does the LFO output goes to?

[defog]

Here is a wiring diagram I just whipped this up real fast to illustrate the number of parts and basic wiring. There may be errors, so proceed with caution. I've always just perfboarded these when I needed them.


Here is the code by Kuki. I did not write this code, I just modified it for my own purposes. There are two versions of this code that I have used. The first illustrated here was used in a Sound Master Rhythm 1 drum machine that didn't have critical trigger timings. The drum sound duration was not dependent on the length of the trigger pulse, it simply needed a High state to trigger. Therefore, this code just sets a digital pin to note on = HIGH Note-off=LOW. NOTE - this code breaks in the most recent version of Arduino because "BYTE" is no longer supported. You'd have to rewrite it to use Serial.Write instead if you want to use a version later than 0021

[defog]

A simple modification to change the pulse-length would be to do something like this:

[defog]

[bikini-inspector]

cheers defog, i will check that out, very cool!

but back to topic:

haha, well that sounds very familiar, check out my box http://vimeo.com/26630135


not sure where to connect the LFO on your APC, as i've built the 556 version.

in general, the apc offers 3 options:

modulate pitch
modulate pulse width
gate (this means as long as a voltage is applied to the reset pin, sound plays)

on the 556, the pins are 3 and 11 for CV and pin 4 for gate.
I'd suggest you just build the LFO and just poke the output around on the APC board to find the sweet spots.

and as always: why not connect these spots to extrenal jacks, so once you've built a sequencer, you can easily interface your stuff

[VanaVara]

[Cynosure]

Sorry to be hijacking this thread for arduino stuff...

defog - Thanks for posting that. I have a few questions since I don't have an arduino yet, but I will get one soon if your code is capable of doing what I need. Please let me know what it can do from the following list:

-Trigger drum sounds that require a 5V pulse.

-Trigger multiple drums sounds simultaneously (at least 5).

-Be controlled over midi using Ableton Live and similar software (not running arduino app).

-Be controlled using a standard midi jack.


Preferably I could assign C1-G1 to each trigger a different sound and play the notes using any midi device (synth, software, sequencer).

[defog]

[bikini-inspector]

so...any progress on this?

sorry i got no schems for you, this was pretty much pieced together....the LFO i used is linked in the video comments. it hooks up to the aforementioned pins on the apc.

any samples/vids ?

btw: thanks defog, i saved that stuff for later

[VanaVara]