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White noise not very random.

White noise not very random.
« on: March 27, 2017, 09:06:13 PM »
Hello all. New owner of an OB6 Desktop here. I love this synth very much. But one thing I've noticed is the white noise sound source isn't very random, we can sometimes hear faint repeating patterns in the noise. I would think that on an instrument in this price range, the white noise sound source would be absolutely random ?
Mind you, it's nowhere near as bad as the dreaded MM5837 digital noise chip from the early eighties, but still not completely random as in a genuine analog white noise generator ( la Oberheim SEM).

Maybe something correctable in an upcoming firmware revision ?
Minimoog D (vintage), OB6 (Desktop), Oberheim Matrix-6 (MIDI Controller), Prophet REV2-16, DeepMind 12

Re: White noise not very random.
« Reply #1 on: March 29, 2017, 03:06:08 AM »
not completely random as in a genuine analog white noise generator ( la Oberheim SEM).

Huh? No such thing. Are you sure that you're not confusing this with the OB-X (also a MM5837)?

This might be helpful: http://electricdruid.net/wp-content/uploads/2015/07/NoiseGen1Datasheet.pdf

Note that the Electric Druid uses an algorithmic noise generator, which is what I suspect that DSI uses as well.
« Last Edit: March 29, 2017, 03:24:54 AM by DavidDever »
Sequential / DSI stuff: Prophet-6 Keyboard, Prophet 12 Keyboard, Mono Evolver Keyboard, Split-Eight, Prophet 2000

Re: White noise not very random.
« Reply #2 on: March 29, 2017, 10:26:21 AM »
Sorry, my bad. I should have referenced the Minimoog D, (or any other transistor, or diode reverse bias white noise sourced synths) not the SEM which does not offer white noise.

The same problem was discovered on Behringer's DeepMind 12 in earlier OS version of the firmware. It has been since corrected and now the synth has a much better white noise source, devoid of any discernable audio patterns.

In this day and age of super fast DSPs, I can't understand why generating endlessly changing, and non-repeating random values can't be so hard to program ?
« Last Edit: March 29, 2017, 10:36:56 AM by AlainHubert »
Minimoog D (vintage), OB6 (Desktop), Oberheim Matrix-6 (MIDI Controller), Prophet REV2-16, DeepMind 12

Re: White noise not very random.
« Reply #3 on: April 03, 2017, 04:07:05 AM »
true random can repeat as much as it wants!

Re: White noise not very random.
« Reply #4 on: April 04, 2017, 09:43:27 PM »
true random can repeat as much as it wants!
You will NEVER hear any repeating pattern (a sequence of digital numbers) in analog white noise.

White noise is defined as all audio frequencies simultaneously. Not a digital memory buffer of fixed length being played twice in a row every two seconds...
Minimoog D (vintage), OB6 (Desktop), Oberheim Matrix-6 (MIDI Controller), Prophet REV2-16, DeepMind 12