Go Down

Topic: Audio frequency modulation (Read 564 times) previous topic - next topic

Antoninbln

Hi people :)

I'm searching around some information for a personal project. I'm wondering if it is possible to use an arduino as a custom audio amplifier.

The context is the following : as an audio amplifier I would like it to process an audio numeric signal (input) to reduce volume or amplitude of a specified window of frequencies to the output. I'm looking for a way to code that kind of program, so I would be able to control the process a maximum, and choose frequencies windows to work on.

Why ? It would allow me to modulate signal by defining myself frequencies windows for basses / middle and high frequencies and process them.

I'm sorry if my post and my reflexion seems unclear, I've been searching for multiple hours and didn't find anwsers I expected. I hope you guys could help me in my reflexion or giving me any idea, even a little one. Thanks you very much !

Have a good day  :)

DVDdoug

#1
Sep 11, 2019, 11:42 pm Last Edit: Sep 11, 2019, 11:51 pm by DVDdoug
The Arduino is not powerful enough for that.


The cheapest and easiest way is with analog op-amp filters.  Standard filter configurations are high-pass, low-pass, bandpass, and band-reject.   

It can also be done with digital signal processing but it generally takes a computer or a specialized DSP chip.   There is something called the MiniDSP which comes in a variety of configurations and I think  it's "easy" to program.   (In general, DSP is advanced programming.)

There is an old book called Active Filter Cookbook but I'm sure you can find the same information online.

Quote
Why ? It would allow me to modulate signal by defining myself frequencies windows for basses / middle and high frequencies and process them.
It sounds like you want a crossover.    "Electronic" crossovers (like the link) are used with line-level signals which go into separate power amplifiers in a bi-amplified or tri-amplified (or more) setup with separate amplifiers for the woofer, midrange, and tweeter.   Big stage-show systems are usually tri or quad-amped.   Some "big" car audio systems are configured like this. 

There are pro audio power amplifiers with built-in DSP filtering so you don't need a separate crossover and there are car amplifiers with built-in filters (probably analog).

Something similar is done with home theater systems...   The bass from the surround speakers is usually re-routed to an "active" subwoofer with an amplifier (and sometimes a low-pass filter) built-in.

2-way and 3-way hi-fi speakers have a built-in passive crossover network.   

-----------------------
An "amplifier" boosts the signal.   A microphone preamp boosts the millivolt microphone level to audio line level (about 1V).   A power amplifier takes a line-level input and boosts the voltage & current to drive a speaker.   A guitar amplifier has a preamp and power amp built-in.

"Modulation" is variation.   AM (amplitude modulation) varies the signal up and down.   If you rapidly cycle your volume control up & down, that's  modulation.   That can be done electronically or digitally and it can be used as a special effect called "tremolo".    Frequency modulation as an audio effect is "vibrato".

MarkT

Hi people :)

I'm searching around some information for a personal project. I'm wondering if it is possible to use an arduino as a custom audio amplifier.

The context is the following : as an audio amplifier I would like it to process an audio numeric signal (input) to reduce volume or amplitude of a specified window of frequencies to the output. I'm looking for a way to code that kind of program, so I would be able to control the process a maximum, and choose frequencies windows to work on.

Why ? It would allow me to modulate signal by defining myself frequencies windows for basses / middle and high frequencies and process them.

I'm sorry if my post and my reflexion seems unclear, I've been searching for multiple hours and didn't find anwsers I expected. I hope you guys could help me in my reflexion or giving me any idea, even a little one. Thanks you very much !

Have a good day  :)
You want to make an active crossover?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

CarlWatson

I have some issue with its tones

pjrc

This statement was true long ago.  Technology has improved greatly in the last 10 years!

It can also be done with digital signal processing but it generally takes a computer or a specialized DSP chip.
Today 4 categories of 32 bit ARM microcontrollers exist.

Cortex M7 (Teensy 4.0) would be massively overkill, unless *many* filters are needed.

Cortex M4 (Teensy 3.x & Adafruit Metro M4) is plenty powerful enough to run this sort of filtering & remixing with variable gain.

Cortex M3 (Arduino Due) could probably do it.

Cortex M0+ (Adruino Zero & MKR, Teensy LC) might be able to do this in a very limited way, but getting to keep up in real time would be a huge challenge.

Of course this is far beyond the old 8 bit AVR chips.

Go Up