Hello, im sending audio from the ADC to the DAC directly and im having a bit of background noise. Its not to loud to make unusable, but loud enough to notice when there is no audio.
Its been a couple of day since im trying to reduce it with no success.
My signal chain is:
Guitar -> opamp buffer -> RC LP filter (3.3k, 3.3nF) -> opamp inverter stage, unity gain ( rin = 100k, rfeedback = 100k) -> RC LP filter (3.3k, 3.3nF) -> 3.3uF cap -> ADC (with adc bias as per the audio GUI example on adc). Both my AGND and DGND are tied together. Already tried to untied them with no reduction of noise.
The opamp is a TL072, im taking the supply from the 3.3v reference.
I already tried to eliminate the signal conditioner stage (all the signal chain stated earlier), to see if it wasn't the 3.3v being noisy, but the noise still persist.
What caught my attention was that connecting the ADC input directly to ground, made the noise a lot more quieter.
Im alright with having 12 bits of resolution if that keep out the noise. Where should i mod the code to do that? I looked at https://github.com/PaulStoffregen/Audio/blob/master/input_adc.cpp but im not sure where to mod.
Im thinking something like ADCvalue = ADCvalue & 0x0000111111111111 or ADCvalue = ADCvalue>>4
Its been a couple of day since im trying to reduce it with no success.
My signal chain is:
Guitar -> opamp buffer -> RC LP filter (3.3k, 3.3nF) -> opamp inverter stage, unity gain ( rin = 100k, rfeedback = 100k) -> RC LP filter (3.3k, 3.3nF) -> 3.3uF cap -> ADC (with adc bias as per the audio GUI example on adc). Both my AGND and DGND are tied together. Already tried to untied them with no reduction of noise.
The opamp is a TL072, im taking the supply from the 3.3v reference.
I already tried to eliminate the signal conditioner stage (all the signal chain stated earlier), to see if it wasn't the 3.3v being noisy, but the noise still persist.
What caught my attention was that connecting the ADC input directly to ground, made the noise a lot more quieter.
Im alright with having 12 bits of resolution if that keep out the noise. Where should i mod the code to do that? I looked at https://github.com/PaulStoffregen/Audio/blob/master/input_adc.cpp but im not sure where to mod.
Im thinking something like ADCvalue = ADCvalue & 0x0000111111111111 or ADCvalue = ADCvalue>>4