[sdiy] Noob Question: Passive Filter Design

[Oren Leavitt]

Colin f wrote:
>  
> 
>>I have a circa 1967 Ace Tone "Rhythm Ace" FR-1 beat box - it 
>>uses inductors for the various percussion voices.
> 
> 
> Ditto the Korg Minipops 7.
> PCB photo and schematics are here:
> http://www.colinfraser.com/mp7/index.htm
> Many of the sounds have no active components at all, or just a single
> transistor buffer.
> They are just resonant LC filters fed with trigger pulses.
> Count the inductors.
> Then think how long it would take you to wind them by hand.
> Has anyone ever played with gyrator-based copies of this sort of thing ?
> 
> Cheers,
> Colin f
> 

Ah yes - the MP7, another one that should "inductored" into the LC hall 
of fame. I do have one of those under the Univox SR-95 badge. It gets 
refered to as the "Nuclear Insect Orchestra" when the Guiro and the 
Quijada are going :-)
I will concur that this would be a tough one to clone.

As for non-LC options, an array of resonant twin-tee bandpass filters, 
like the two-transistor PAiA 2720-3B, might be an interesting option to 
play with.

- Oren