[sdiy] Best ideas for (2) MN3004 BBDs?

[David Moylan]

The MN3004 is a 512 stage, which doesn't really make it that useful for 
long delays per say, probably better for chorus/flanger circuits.  You 
should maybe check out the Arp Omni chorus schematic.  It uses 3 
SAD512's (similar 512 stage BBD) in parallel modulated by 3 separate 
LFOs to generate it's string sound.  No compansion is used and the BBDs 
are each driven by a separate CD4046 PLL used for the VCO core.  I think 
the circuit uses the XOR in the 4046 to invert the clock so you have the 
necessary 2 phase clock signal for the BBD.

The omni doesn't include the dry signal in the mix; I've been thinking 
about adding the dry signal on my Omni2 to see what affect it has on the 
sound.  I'll bet two stages of this plus the dry signal and compansion 
would sound pretty good still.

If you need I can make a copy of the schematic.

Dave Moylan

Amos wrote:

> Hey all...
>
> I just scored a pair of MN3004 BBD chips and would like to build 
> something cool with them.
> Do I need the associated clock chips, or can I clock them from a 
> homebrew VCO/LFO of some sort?  Does anyone have a link to some good 
> projects for this one?  According to the datasheet I can get 25.6ms 
> max delay from each chip, I am assuming this could be underclocked for 
> longer lo-fi delay though.
>
> All ideas/opinions welcome... thanks!
>
> -Amos