I have quite a few questions related to my project. I work as a DJ and just started with Arduino, and what I want to do is to be able to read the audio signal to sync some LEDs to the music (hopefully the bass kick), among other things.
I've read a lot of tutorials, including one that uses an Op-Amp to power the low level signal and then a DC Offset to create a readable range for the Arduino analogs, but I'm afraid that having a capacitor in series creates a high-pass filter, reducing the frequency that I actually want to read. Link to said tutorial: http://www.instructables.com/id/Arduino-Audio-Input
Is there another way to do this? What if I simply hook a Diode to protect the analog input from negative audio signal? Or use a transistor to control the amount of electricity it could flow from the 5V source to an input? (there are so many transistors that I'm naively hoping one could work with low level audio signals to its base pin). If not, how could I avoid the High-Pass Filter or improve the kick detection?
I don't think I need to change any sampling frequency (Configuring ADC to take input samples faster) or do any complex stuff in the code, as I don't really find the need to process the signal yet. Plus, reading distorted signals actually creates a cool effect: Right now, analog input is centered around 510 (10 bit) and I just read the high peaks (say, values between 700 and 1000) and map them to 8 bit to a PWM output, so the LEDs blink really fast and to the beat (sort of). The audio signal coming to the Arduino will not be used for speakers, or any other equipment that might get damaged by this distorted signals (so using cheap Op-Amps or whatever else might distort sound signal a little bit is not a big deal, compared to using a mic to read the sound "pressure" in a place where everyone is shouting), but I just want to make sure that this wont damage the Arduino either. The rest of the ideas for this project are switch or time controlled so are safe from distorted audio signal.
Sorry it took me that much to explain, but I feel that I have read and learned more this two weeks than in my whole school life and still have many questions and concerns. Thank you very much!