[sdiy] analog loses another niche

[Harry Bissell]

has anyone tried to clone the MM5837 ???

</troll>

H^) harry


----- Original Message -----
From: Scott Gravenhorst <music.maker at gte.net>
To: synth-diy at dropmix.xs4all.nl
Sent: Thu, 01 Jul 2010 10:54:19 -0400 (EDT)
Subject: Re: [sdiy] analog loses another niche

Tim Ressel <madhun2001 at yahoo.com> wrote:
>One fine day I got clever and hooked up a LFSR to an RF spectrum 
>analyzer. I thought with averaging turned on I would see a 
>straight line. Instead what I saw was a picket fence of peaks, or 
>in RF parlance, a comb generator. With an 8-bit LFSR the peaks 
>were quite pronounced, with a 16-bit they were so close together 
>it was tough to see them, but they were there. Bottom line: 
>digital noise really does sound different, unlike CDs that have 
>been purified with flashing LEDs. 

I have an image file somewhere with the spectra of different waveforms, LFSR output was one
of them and yes, it's a picket fence sort of thing and as you wrote, the longer the
register, the closer the pickets.  According to another poster from some time back, this is
predictable and can be calculated (Magnus perhaps?).  

In my experimentation, I've been using LFSRs of 64 or more bits.  IMO, with such a long
LFSR run at very high rates, the noise is, to me, indestinguishable from a good analog
noise generator.  As I said: IMO.  And dare I write that with such long LFSRs is it
possible that a digital noise generator could actually sound better than an analog noise
generator?  I think so - IMO.

Scott (LFSR) G.



>----- Original Message ----
>From: "jays at aracnet.com" <jays at aracnet.com>
>To: Synth DIY <synth-diy at dropmix.xs4all.nl>
>Sent: Wed, June 30, 2010 4:32:13 PM
>Subject: Re: [sdiy] analog loses another niche
>
>I wonder is an analog source any better than some form or 
>combination of pseudo-random long length LFSRs? 
>
>Jay S.
>
>Tom Corbitt wrote:
>
>> http://spectrum.ieee.org/computing/hardware/intel-makes-a-digital-coin-toss=
>> er-for-future-processors
>> 
>> =94Historically, RNGs have been analog,=94 says Greg Taylor, director of
>> the Circuit Research Lab. =94But porting to smaller technology nodes
>> [with analog devices] requires a lot of fine-tuning that is
>> unnecessary with digital versions.=94
>> 
>> Be interesting to see how they rigged the metastability to be a 50/50 shot.
>> 
>> 
>> Tom "And I, for one, welcome our new randomly digital overlords" Corbitt
>> _______________________________________________
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-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
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