Noise from USB Host connector on Teensy 3.6 internal DAC

Status
Not open for further replies.
Hello to everyone, I start a project of synth with teensy 3.6 via its internal dac. I found a simply sketch to try the MIDI to synth connection.
I connect on USB Host port an ARTURIA MINI LAB MK2 MIDI CONTROLLER. The power supply is only from teensy USB via computer.
The system work well but I have a noise on DAC when any led on the ARTURIA goes ON. If any led don't blink the sound is good, but I have a 400 Hz noise perfectly synchronous with the blink led.
If I press one PAD with led the noise is continous.
If I use a phone charger for teensy, the noise is so low ( but present anyway)

I use this code:
View attachment MidiSynthKeyboard.zip

thanks a lot

ScopeMaster
 
Such things can be expected from internal ADCs and DACs.
They are never as good as external devices.

The easiest fix might be not to blink...
If the problem is intruduced by the ARTURIA, some capacitors on the power-lines might help to filter the noise.
 
thanks, I try with a 100 uF capacitor and a 100 nF on USB host power line, but nothing changed. I try with another keyboard, the Arturia Keystep, that have external power supply connector. If I connect the external power supply the noise is like the phone charger. The problem I think is the current consumption from the USB Host port. I measure the current. Arturia MINI LAB have 100/120 mA with led ON ( no more current with more leds, I think are multiplexed). Teensy use 100/120 mA. the pc port have 200 mA without handshacking more current. But is strange the noise, fixed at 400 Hz, with athe two keayboard. I try on LENOVO T420 that have one port with 500 mA in any case, but the problem still the same. the same with Mac.
 
Status
Not open for further replies.
Back
Top