Pavel posted Jan 4, 21:44:
I'm making a pocket-sized version of SamplerBox and decided to design a custom board that will have all peripherals onboard and simply plug into Raspberry GPIO socket resulting in a compact and sturdy SamplerBox.
At a very minimum the board will have: display for patch number and selector buttons, possibly several general-purpose buttons/knobs, Li battery charger circuitry, hi-quality audio interface (connected to Raspberry over GPIO), low-pass filter and headphone amplifier with volume controls.
Although I started to do it for my own needs, I want to keep hardware open-sourced and easily extendable.
Please comment if you would be interested to use such board. I'd like to learn in what setup do you currently use your sampler boxes (studio, club or on the go? what do you connect to inputs and outputs?), whether you had experience with Raspberry previously, what new features you are interested in.
JPG posted Jan 4, 23:34:
I think a midi in and a midi out/thru would be useful to add on the board.
Mirco posted Jan 5, 00:33:
Pavel posted Jan 5, 05:27:
JPG, how would you use midi ports? Realistically because of dimensions and circuitry there is a tradeoff: its either pocket size or midi ports
Francesco posted Jan 5, 12:04:
Pavel posted Jan 5, 19:05:
I see two options, mutually exclusive to an extent:
- pocket-sized device, Raspberry HAT compliant board (smaller than the Raspberry itself), headphones and RCA outputs. With controls that would likely mean no space for DIN MIDI port although a non-standard MIDI connector can be fit (i.e. minijack)
- somewhat bigger device, MIDI IN/THROUGH ports, balanced TRS outputs in addition to headphones
I'm not fixated on pocket-size. If latter option makes more sense for the community I might as well choose to go with it.
JPG posted Jan 5, 21:23:
It depends of the size of your pocket, no? ;-)
If you want to bring your sampler box anywhere, I think you will have to also bring a keyboard... in your pocket ;-) I'm joking of course! I really find your project interesting.
The midi IN is useful to control the microsampler by my midi footcontroler (I'm guitarist!)
The midi OUT/THRU is perhaps not essential but it is pratical to avoid a midi box when you have to plug several midi devices.
I find TRS useful too.
herbert posted Feb 19, 20:03:
I agree, great idea, but would prefer MIDI In too (besides USB in)
Pavel posted Feb 19, 23:25:
Thank you for the feedback guys! I really value it.
I've been proceeding with this project. Prototype PCB testing is complete at this point and it is being prepared for manufacturing.
The current design is a 10cm x 10cm PCB that holds all required peripherals and plugs into Raspberry PI GPIO socket, eliminating the need for any wiring as DAC, all peripherals and connections are placed onto one board. It is designed to fit stylish aluminium off-the-shelf 12x12x4 cm enclosure.
Current specs are:
Onboard high-quality PCM5122 DAC tested to work with SamplerBox and high-fidelity TPA6133A2 headphone amplifier.
- midi in/through
- stereo 1/4” TRS out (can be connected to balanced or unbalanced inputs)
- patch change buttons
- 16x2 display
- GPIO pin header (for DIY extensions)
- 1/4” headphones out
- headphones volume knob
- USB for samples driver / devices (Raspberry PI on onboard SD-card)
- microUSB 2A power input
JPG posted Feb 21, 17:21:
Alien posted Feb 21, 23:04:
Pavel posted Feb 23, 14:55:
I've created a page on Hackaday and a maillist to share pictures and occasional progress updates without spamming the forum too much: https://hackaday.io/project/9825-samplerbox-1
JPG posted Feb 27, 06:31:
Don't hesitate to give some news here too!
Cailen posted Feb 27, 15:45:
Pavel posted Feb 7, 16:54:
Thank you everyone who replied on this thread and supported the idea. I went on with the project and completed the board. I'm obviously very excited but it objectively works great
See https://hackaday.io/project/9825-samplerbox-1/log/52979-fully-working-sampler-board for details