Hissing

I am experiencing a hiss while playing WAV files. Can I put any filtering on the speaker to get away the hiss? Thanks! baum

baum: I am experiencing a hiss while playing WAV files. Can I put any filtering on the speaker to get away the hiss? Thanks! baum

Hiss sound is from electrical noise in the circuit, find the source of the noise and that is where the filtering needs to be done. It's really too late to do the filtering at the speaker after the signal has been amplified along with the noise, they are both (the signal and the noise) valid audio frequencies at that point in the circuit. A scope is a useful instrument to find which stage might be at fault, or perhaps even coming from the input signal itself?

Schematics of the total audio circuit chain would be useful to discuss possible sources of the noise.

Lefty

Well I'm having it on my computer. :( I got an mp3 from itunes and turned it into a wav file to play it, but now I here a hiss. would any filters help?

baum

How are you playing it back? What is the DAC-amplifier-speaker path?

Nothing yet. When playing it on my computer, I here the hissing, so was wondering what I can do on the arduino (or computer) end to clean things up.

I think all you can is get some filtering software and run the file thru that. Like the software used to record records into .wav's, with "scratch removal" function. It might help, or it might make it sound like you are losing some of the high end.

Maybe something like this http://audacity.sourceforge.net/

"Effects

Change the pitch without altering the tempo, or vice-versa. Remove static, hiss, hum, or other constant background noises. Alter frequencies with Equalization, FFT Filter, and Bass Boost effects. Adjust volumes with Compressor, Amplify, and Normalize effects. Other built-in effects include: Echo Phaser Wahwah Reverse "

If there was no hiss when it was an MP3 file then it sounds like there is nothing wrong with the amplifiers in your computer. It could just be the precision / sample rate of your converted file. I suspect there is nothing you can do at the audio end.

Audio converters can be pretty rubbish - what software did you use to convert it?

I used iTunes, as recommended by Sparkfun, but I will try audacity. Funny thing is, sample rate didn't seem to affect it. All 8-bit wav files had the hissing.

Also, I realized that the original audio being from an LP, even the Mp3 had a small amount of hissing. It seems to just have been amplified to some degree.

8-bit! I imagine you lost tons of fidelity going to that.
So you went from like 65,000+ levels of granularity, down to 256. I think you are stuck with the hissing.

alright.

8 bits is simply unsuitable for music by most people's standards.

I doubt you'd notice if you were using apple earphones :D

The 8-bit is to play on a DAC... I do have a 12 bit I2C DAC, maybe I can divide the 16-bit wav file by 16 (2^4) to get 12 bits.

baum

some little novelty gadget or something.

Yep.

What was the sampling rate? There might be frequency aliasing too :(

Both 22kHz and 44kHz caused hissing; both were 8 bit.

baum