[sdiy] Vote for your favorite noise source

[Ian Fritz]

This was hashed out in some detail about a year ago. You might want to 
check out the interesting posts in the archives.

My own opinion runs quite contrary to the traditional wisdom -- but I have 
backed it up with some careful measurements.

What I found was that it is most definitely a bad idea to use the noisest 
diode you can find. The higher the noise level, the more 1/f noise there 
is, giving a very rough sound. Avoid the 2N2712 at all costs.

For smooth noise the best way is to use a general purpose transistor and to 
select for the flattest white noise spectrum. Out of about 50 2N3904's I 
found three with a decently flat spectrum, and one with an excellent 
response. But again -- the ones with the best spectrum had the lowest noise 
level.

I also designed an improved simple pink noise filter, but the overwhelming 
response of the list was that having an accurate pink spectrum was not at 
all important for musical applications.

You will get some interesting responses, I predict.

   Ian



At 02:25 AM 5/13/2002, Tim Ressel wrote:
>Okay boys and girls, Its time to throw caution to the
>wind and start a new holy war:
>
>Part 1:
>
>(*)-(*)-(*)-(*)-(*)-(*)-(*)-(*)
>Which Noise Source Is The Best?
>(*)-(*)-(*)-(*)-(*)-(*)-(*)-(*)
>
>
>Candidates:
>
>Reversed-biased PN junstion (2N2712)
>Above with constant-current source
>Reversed-biased zener
>Dual reversed-biased zener (MOTM??)
>Mondo shift register with feedback
>Small hungry infant
>Other?
>
>
>Part 2:
>
>(*)-(*)-(*)-(*)-(*)-(*)-(*)-(*)
>Which Pink Filter Is The Best ?
>(*)-(*)-(*)-(*)-(*)-(*)-(*)-(*)
>
>
>Have fun!
>
>--TR
>
>
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