Drum machine / step sequencer build

saor

saor

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Been wanting a hardware sample box / drum machine for a while now. Something portable I can take with to jam sessions to tap out a beat with. Couldn't really find anything locally so...DIY it is. But the problem is that things escalate with DIY. So what started as a box with 4 sample banks I can trigger with arcade buttons grew to include a step sequencer that can also sync to midi-in.

Decided to use an ESP32 board - think it handles audio processing better than Arduino.

ESP32 board:
esp.jpg

Some quick component holders:

HOLDER.png

mak.png

I need to learn to be tidy...

p1.jpg

Things were all over the place so printed a better temp housing:

p3.jpg


p4.jpg

Think I blew the ESP32 board with some silly wiring. So just waiting for a new board then continue.
 
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Planning controls and some UI. Going to get an expander board for the ESP32 so that more buttons can be added. Would prefer a clear layout rather than try squeeze multiple functions out of too many buttons.

LAYOUT-1.png
 
Mad respect for all the work to do that but wouldn't it be easier to just get a wireless M Vave SMC pad and pair that with an iPad or iPhone app?
 
airborne said:
Mad respect for all the work to do that but wouldn't it be easier to just get a wireless M Vave SMC pad and pair that with an iPad or iPhone app?
Click to expand...
I'm at the point where I spend so much time on my PC and phone during the day that when it comes time to relax and play music I want nothing to do with those devices. Loop station arriving later this month so I no longer need the PC for that either. And a guy needs his hobbies.
 
saor said:
I'm at the point where I spend so much time on my PC and phone during the day that when it comes time to relax and play music I want nothing to do with those devices. Loop station arriving later this month so I no longer need the PC for that either. And a guy needs his hobbies.
Click to expand...
True, it is far better to have an instrument rather than a software one inside a box
 
saor said:
I'm at the point where I spend so much time on my PC and phone during the day that when it comes time to relax and play music I want nothing to do with those devices. Loop station arriving later this month so I no longer need the PC for that either. And a guy needs his hobbies.
Click to expand...
Dude what did you get for the loop station? I hate using the pc as same I sit in front of it the whole day. They quite pricey.
 
Only thing not connected is the SD card reader so we're still without sound. Still need to connect a few buttons etc but most of the functionality is there now.

MK1.png

MK2.jpg

The new brain - bigger ESP32 with more inputs and memory:
MK3.jpg

DAC with headphone jack:
MK4.jpg

Haven't got sound yet so a bit hard to see what's going on but anyway - quick video:

 
Sound! Took a while with the wiring - getting the DAC and the SD card reader on their own power supply fixed a lot of issues. Everything shares a common ground so a lot of noise still creeps in but will try address this soon with some resistors etc. But **** yeah - it's working! Samples loaded onto SD card then loaded into RAM once selected - playback is nice and snappy. Also very happy with how the step sequencer works - adding and removing hits works well.

 
It’s working nicely but that ground loop hum bs, the bane of my life.
It’s often caused by shtty switch mode power supplies, I've found Samsung usb chargers are very low noise, can you power it from usb perhaps?
 
airborne said:
It’s working nicely but that ground loop hum bs, the bane of my life.
It’s often caused by shtty switch mode power supplies, I've found Samsung usb chargers are very low noise, can you power it from usb perhaps?
Click to expand...

He has 2 power sources and I don't see a common ground between them so that would be the first thing to try and hopefully just a single supply when its done.
But yes I hear you on cheap switchmode supplies being a pita.
 
airborne said:
It’s working nicely but that ground loop hum bs, the bane of my life.
It’s often caused by shtty switch mode power supplies, I've found Samsung usb chargers are very low noise, can you power it from usb perhaps?
Click to expand...
Right now the ESP32 is connected to pc via usb, will replace with a phone charger and see. The DAC and SD card and LED matrix are connected to the breadboard power supply which is mains powered.
B-1 said:
He has 2 power sources and I don't see a common ground between them so that would be the first thing to try and hopefully just a single supply when its done.
But yes I hear you on cheap switchmode supplies being a pita.
Click to expand...
All grounds are connected - that breadboard power supply has a connection to the ESP32 ground. Maybe you guys can answer: Does the order in which components are connected to ground matter? Right now I'm just connecting to ground sort of at random, using multiple ground points on the ESP32. I've seen mention of star grounding. Is there a basic principle of grounding various components in the same system I need to be aware of?
 
saor said:
Right now the ESP32 is connected to pc via usb, will replace with a phone charger and see. The DAC and SD card and LED matrix are connected to the breadboard power supply which is mains powered.

All grounds are connected - that breadboard power supply has a connection to the ESP32 ground. Maybe you guys can answer: Does the order in which components are connected to ground matter? Right now I'm just connecting to ground sort of at random, using multiple ground points on the ESP32. I've seen mention of star grounding. Is there a basic principle of grounding various components in the same system I need to be aware of?
Click to expand...
PC usb power can be very noisy, definitely try a genuine Samsung USB charger, I suppose a genuine Apple one may be just as good but I've had great experience with Samsung chargers mitigating power supply noise on a little digital amplifier. That could actually be where the bulk of the noise is coming from.

Star grounding is one of the gold standards, having separate grounding points is exactly how ground loops form because the ground seeks the shortest route and if that's not via the actual ground it will find an unwanted ground path through another component or section of the electrical topography.
 
airborne said:
PC usb power can be very noisy, definitely try a genuine Samsung USB charger, I suppose a genuine Apple one may be just as good but I've had great experience with Samsung chargers mitigating power supply noise on a little digital amplifier. That could actually be where the bulk of the noise is coming from.

Star grounding is one of the gold standards, having separate grounding points is exactly how ground loops form because the ground seeks the shortest route and if that's not via the actual ground it will find an unwanted ground path through another component or section of the electrical topography.
Click to expand...
Got home, changed nothing, switched on as usual and getting no noise at all - or what's there is so low that it's not worth bothering with. This is with pc usb power or charger power. Ghost in the machine. But at least I know that a low noise floor is possible without a bunch of extra components. Kinda surprised that it's running so quiet now - was expecting to do a lot more work.

 
Most of the functionality and UI tinkering done. It's a problem: I'll put my head on the pillow at night and immediately think of more stuff to add. And it's fun doing it. It's grown beyond the simple sample player I started with and has become a decent little sequencer. Think I'm going to start drawing up the electronics layout then move everything to a universal prototyping board (green one with holes) and start with the housing.

Velocty, FX and pitch controls for each track. Only have delay effect for now.
11.jpg

55.jpg

Velocity controls:
22.jpg

Pitch controls:
33.jpg

And something I never anticipated at the start: Song mode to chain sequences together.
44.jpg
 
Also - for anyone with even a mild interest in diy electronics / have kids with an interest - these boards are really not expensive. For the price of 2 or 3 coffees you've got a little pc to play around with and the internet is full of tutorials.

ERD.png

Micro Robotics- Centurion Stellenbosch - Arduino Importer

Micro Robotics, Importers, Arduino,Sensors, Robotics, Pololu, Adafruit, DF Robot, Raspberry Pi, Beaglebone Black, Teensy, Stepper Motor, South Africa
www.robotics.org.za www.robotics.org.za
 
saor said:
Also - for anyone with even a mild interest in diy electronics / have kids with an interest - these boards are really not expensive. For the price of 2 or 3 coffees you've got a little pc to play around with and the internet is full of tutorials.

View attachment 1903788

Micro Robotics- Centurion Stellenbosch - Arduino Importer

Micro Robotics, Importers, Arduino,Sensors, Robotics, Pololu, Adafruit, DF Robot, Raspberry Pi, Beaglebone Black, Teensy, Stepper Motor, South Africa
www.robotics.org.za www.robotics.org.za
Click to expand...
I have a few ESP-32's lying around here. I want to hook up some sort of thing for my son to play with... he is 7... so I need make some sort of "can only connect correctly" setup. lol

He is crazy about anything power/electricity related. He is figuring out redstone on minecraft currently.
 
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