Hi, I am thinking about something and would be glad to hear some input about it.
I have done some project which uses teensy 3.6 together with the audio board for guitar effects.
It turns out, that 16bit is not good enough, if you want to do overdrive sound with DSP. It can be used, if you put a compressor or a high pass filter in front of it and if you take very good care about signal strength.
So the idea is to use a resistor and two antiparallel diodes as a non linear voltage divider before the adc. This is done quite often in guitar electronics to achieve distorted overdrive sound.
The non- linearity of the diode is described by the https://en.wikipedia.org/wiki/Shockley_diode_equation .
The idea is to take then the distorted sound after digitalisation and calculate back the linear values. (Calibration needed) This means, that then numbers are in a bigger range than 16 bits. The floating point audio library will be needed here.
After DSP, the values have to be compressed again with math, put through the DAC and be expanded again.
1. Well, yes it would be more straight away, if there was a 24bit audio card with a good price available, that can be connected to teensy 3.6 and/or 4.1 and has a driver. - I cannot solder too small parts and have doubts that I can write a device driver. So that is the first question, what can I buy?
2. Is the floating point audio library already working with teensy 3.6 and 4.1?
3. What are your thoughts about the non - linear setup as described?
The following picture shall give an impression of the both analog parts of compression and expansion.
Thank you very much. Christof
I have done some project which uses teensy 3.6 together with the audio board for guitar effects.
It turns out, that 16bit is not good enough, if you want to do overdrive sound with DSP. It can be used, if you put a compressor or a high pass filter in front of it and if you take very good care about signal strength.
So the idea is to use a resistor and two antiparallel diodes as a non linear voltage divider before the adc. This is done quite often in guitar electronics to achieve distorted overdrive sound.
The non- linearity of the diode is described by the https://en.wikipedia.org/wiki/Shockley_diode_equation .
The idea is to take then the distorted sound after digitalisation and calculate back the linear values. (Calibration needed) This means, that then numbers are in a bigger range than 16 bits. The floating point audio library will be needed here.
After DSP, the values have to be compressed again with math, put through the DAC and be expanded again.
1. Well, yes it would be more straight away, if there was a 24bit audio card with a good price available, that can be connected to teensy 3.6 and/or 4.1 and has a driver. - I cannot solder too small parts and have doubts that I can write a device driver. So that is the first question, what can I buy?
2. Is the floating point audio library already working with teensy 3.6 and 4.1?
3. What are your thoughts about the non - linear setup as described?
The following picture shall give an impression of the both analog parts of compression and expansion.
Thank you very much. Christof