Hello, i want some help regarding the hardware schematic for allowing the audio signal to be splitted into 8 bands then connected to mux then to analog input of arduino (actually making a 8 band spectrum analyzer with a midi controller also).
I have created two schematics in my mind but i m not sure which of them will react better with the analog readings for arduino.
Please note that the op-amp is lm386 and the filters are passive RC filters.
So the basic question is to get the true voltage analog reading for each band, should i shift the signal upwards or rectify it?
For the op-amp should it better be placed before filters or after the mux ?
If i ignored the part of the rectifier/clamper as first stage and just directly connected the audio signal to amplify it first. That means i ll lose the -ve part of the audio signal right?
If i used a Pot with the input as in http://itp.nyu.edu/physcomp/sensors/Reports/CondenserMicrophones
this will add a positive DC offset to the audio signal to shift it all upward, i will no longer need the clamper? and if he already shifted it all upwards why did he use the rectifier at the end? ( I understand the he removed DC offset after amplification using the capacitor but he used another voltage divider to shift it up again (correct me if i m wrong.
Would it be better if i used the audio input directly to filters then multiplex them then rectify then amplify?
Sorry if it took so long and sorry for the bad block diagrams...