Built up 9/15 filters this week gone.
I don't have any equipment in the lab that I can bode plot with (I was referred to an audio analyzer, which I will try to use in one of the other labs).
So for now I just build a filter, then test it on the scope. So I send a sine wave into it whose frequency is that of the center frequency of the filter, then I increase the frequency and decrease it below that to ensure that the amplitude of the wave drops off. Which they are doing thus far. So that's my rough test to confirm that the filters are working as designed until I get actual bode plots to see the full response.

I predict that i'd finish the rest of this filters this week then construct this circuit

http://sound.whsites.net/project75.htm


Something I was wondering regarding this design that the author didn't really cover, was the input filter(Formed by C1 and R1), how do I go about choosing the right cutoff frequency? Is it supposed to be the frequency of my highest band? Also what purpose does R2 really serve?

 

So last week I fully implemented the digital interface, and everything works. It plays and sounds amazingly.
I have to verify the final response with a bode plot. Will do that either tomorrow or next week.
I also have some quirks in the user interface itself to work out as well.

 

So last week I fully implemented the digital interface, and everything works. It plays and sounds amazingly.
I have to verify the final response with a bode plot. Will do that either tomorrow or next week.
I also have some quirks in the user interface itself to work out as well.

Hi,

Maybe you could produce a wav file with it too so we can hear what it sounds like at different settings.

 

Something I was wondering regarding this design that the author didn't really cover, was the input filter(Formed by C1 and R1), how do I go about choosing the right cutoff frequency? Is it supposed to be the frequency of my highest band? Also what purpose does R2 really serve?

The author of that article chose a number of bands and gave the values. Rod choose the octaves, half-octaves, and third-octaves in his design. You need to decide what are the frequencies each of your 15 bands are going to cover. Your slicing up the audio band in your design.

 

Hi,

Maybe you could produce a wav file with it too so we can hear what it sounds like at different settings.

Sorry for the late reply...this was us testing it in the lab about a week ago...my friend selected that song lol

The author of that article chose a number of bands and gave the values. Rod choose the octaves, half-octaves, and third-octaves in his design. You need to decide what are the frequencies each of your 15 bands are going to cover. Your slicing up the audio band in your design.

Thanks man. I already selected the frequencies etc during my design phase, it's just the rationale behind the input passive filter that I was a bit unsure about.