MickMad
Well-known member
Hey there,
I'm working on this project full time since 5 months now: https://hackaday.io/project/20982-mad-modular-audio-devices
It's a set of modules aimed towards hifi audio applications with the Teensy 3.x
The CORE module sports an AK4558EN from AKM and a ultra-low noise LDO for the analog power, stereo input and output on 2.54mm headers that also provide power to small external amplification modules (cleaned by an LC filter on the USB/ext. 5V power supply), and a Teensy pins breakout on one side on 1.27mm pitch headers. The breakout headers might go away in the next revision to leave place for external RAM chips like on the Teensy Audio Shield, but I was planning on using that breakout for future modules. The 2.54mm headers can be connected either to small breakouts that I designed for 1/4" TRS jacks and for 1/8" jacks for simple applications, or to external analog interfaces. The CORE module also provides solderable jumpers to easily configure the board to use either I2S channel available on the Teensy, so that you can stack two boards together and have 4 ins 4 outs.
The IN module sports two THAT Corp 1246 differential line receivers with per-channel volume control, +4dBu or -10dBV reference level switch, and external preamp modules inputs selectable with a pushbutton; the OUT module sports a stereo volume control with impedance-balanced ouptuts, auxiliar output for connection with external power amp modules, and a separate headphone output jack selectable with a switch and powered by a ultra-low distortion TPA6120A2 amplifier.
There's also a HI-Z module to be used as an external preamp module for the IN one, that as you can imagine, adapts the signal of an instrument like a guitar to an acceptable signal for the line receivers; this module has its own gain pot and its own mono jack.
Finally, I also developed a small split rail power supply using TI's DC-DC converters and audio-grade LDOs (we're talking of uVs of ripple on the supplies, not mV) to power everything up. The PSU module can be powered by USB, 5V DC on a standar barrel jack connector, or through a terminal block to connect for example a battery pack.
You can read more details on the hackaday.io page.
Now, you might ask, "what's the reason of this post if everything is already on that other page"?
Well, I have the intention of crowdfunding this project and I'd like to know how much people is really interested in such boards. In particular, I'm planning on making a campaing for the CORE module in the next month/months, and I would like to receive some feedback about its functionalities, its pros, its cons, etc. from you guys, you that make the Teensy community thrive. I've been using the Teensy since 2013, my first biggest achievement was getting USB Audio to work and now that's part of the Teensy core library, I already worked with the AK4558 codec and that's already natively supported by the Teensy too; this year with my last job I achieved ultrasound sampling at 700KHz through the amazing Teensy SPI and DMA capabilities, and I'm planning on using that same SPI/DMA duo with a custom serial interface to control a LOT of buttons, LEDs, knobs/sensors etc. to make HUGE control interfaces; I'm planning on making 192 KHz/24 bit audio on the Teensy a stable thing, not just a hack, and I'd love to make ASIO (instead of USB audio) a thing too. I really want to give something back to this community and this is my way of doing it.
I made this post because I want to share the vision I have with you; this is only the beginning of a series of modules that I'm working on to make any kind of audio application powered by Teensy as easy as possible to build and program; the time will come for MIDI IO, Ethernet support with PoE, then some more like a pro level mic interface, fully differential outputs (not impedance balanced, but real, actively driven balanced outs), a more powerful power supply with transformer to be able to use vacuum tubes for preamps, or to make power output amplifiers for passive speakers... I'd like to go as far as I can.
I need time and support to make my vision come true; if I'll get no support, I'll have to go back to work full-time for someone else, bringing someone else's ideas to life, and if that happens, I will not have the time anymore to work on my ideas... you get the point.
I'm waiting for your comments
I'm working on this project full time since 5 months now: https://hackaday.io/project/20982-mad-modular-audio-devices
It's a set of modules aimed towards hifi audio applications with the Teensy 3.x
The CORE module sports an AK4558EN from AKM and a ultra-low noise LDO for the analog power, stereo input and output on 2.54mm headers that also provide power to small external amplification modules (cleaned by an LC filter on the USB/ext. 5V power supply), and a Teensy pins breakout on one side on 1.27mm pitch headers. The breakout headers might go away in the next revision to leave place for external RAM chips like on the Teensy Audio Shield, but I was planning on using that breakout for future modules. The 2.54mm headers can be connected either to small breakouts that I designed for 1/4" TRS jacks and for 1/8" jacks for simple applications, or to external analog interfaces. The CORE module also provides solderable jumpers to easily configure the board to use either I2S channel available on the Teensy, so that you can stack two boards together and have 4 ins 4 outs.
The IN module sports two THAT Corp 1246 differential line receivers with per-channel volume control, +4dBu or -10dBV reference level switch, and external preamp modules inputs selectable with a pushbutton; the OUT module sports a stereo volume control with impedance-balanced ouptuts, auxiliar output for connection with external power amp modules, and a separate headphone output jack selectable with a switch and powered by a ultra-low distortion TPA6120A2 amplifier.
There's also a HI-Z module to be used as an external preamp module for the IN one, that as you can imagine, adapts the signal of an instrument like a guitar to an acceptable signal for the line receivers; this module has its own gain pot and its own mono jack.
Finally, I also developed a small split rail power supply using TI's DC-DC converters and audio-grade LDOs (we're talking of uVs of ripple on the supplies, not mV) to power everything up. The PSU module can be powered by USB, 5V DC on a standar barrel jack connector, or through a terminal block to connect for example a battery pack.
You can read more details on the hackaday.io page.
Now, you might ask, "what's the reason of this post if everything is already on that other page"?
Well, I have the intention of crowdfunding this project and I'd like to know how much people is really interested in such boards. In particular, I'm planning on making a campaing for the CORE module in the next month/months, and I would like to receive some feedback about its functionalities, its pros, its cons, etc. from you guys, you that make the Teensy community thrive. I've been using the Teensy since 2013, my first biggest achievement was getting USB Audio to work and now that's part of the Teensy core library, I already worked with the AK4558 codec and that's already natively supported by the Teensy too; this year with my last job I achieved ultrasound sampling at 700KHz through the amazing Teensy SPI and DMA capabilities, and I'm planning on using that same SPI/DMA duo with a custom serial interface to control a LOT of buttons, LEDs, knobs/sensors etc. to make HUGE control interfaces; I'm planning on making 192 KHz/24 bit audio on the Teensy a stable thing, not just a hack, and I'd love to make ASIO (instead of USB audio) a thing too. I really want to give something back to this community and this is my way of doing it.
I made this post because I want to share the vision I have with you; this is only the beginning of a series of modules that I'm working on to make any kind of audio application powered by Teensy as easy as possible to build and program; the time will come for MIDI IO, Ethernet support with PoE, then some more like a pro level mic interface, fully differential outputs (not impedance balanced, but real, actively driven balanced outs), a more powerful power supply with transformer to be able to use vacuum tubes for preamps, or to make power output amplifiers for passive speakers... I'd like to go as far as I can.
I need time and support to make my vision come true; if I'll get no support, I'll have to go back to work full-time for someone else, bringing someone else's ideas to life, and if that happens, I will not have the time anymore to work on my ideas... you get the point.
I'm waiting for your comments