[sdiy] Moog ladder filter 904a

[Jean-Pierre Desrochers]

Terry,
According to what you suggest 1.2uF is at position#1 (1hz to 5khz)
That's the narrower freq. sweep offered.
Would it be the position#2 or #3 instead ?
> Pos.2) 4Hz to 20kHz
> Pos.3) 16Hz to 80kHz
Wider freq. spectrum to me ?



Le 2014-02-25 11:58, Terry a écrit :
> According to the Moog 904A spec sheet:
> 
> Pos.1) 1Hz to 5 kHz
> Pos.2) 4Hz to 20kHz
> Pos.3) 16Hz to 80kHz
> 
> At the first position, there is a wall at around 5 kHz. No matter how
> much  CV applied the filter only opens so far, easiest to observe with
> white  noise. If the schematic is correct that would be the large
> 1.2uF cap set.
> Pos.2 would be the middle ground with the .3uF set.
> 
> 
> 
> Have a Moog 902A Band Pass Adapter I'm trying/experimenting with right
>  now. Someone recently auctioned one off on Ebay. There were enough
> photos  of the board to try and reverse engineer. Works in conjunction
> with the  902 VCA. Always wondered what that other Moog filter sounded
> like.
> 
> 
>> In the following circuitv there is a 3 way switch
>> that selects the VCF freq 'range' (3 capacitors set choices)..
>> 
>> http://www.freeinfosociety.com/media/images/4145.jpg
>> 
>> Which capacitors set would provide full freq range sweep ?
>> 
>> C1: 1.2uF
>> C2: 0.3uF
>> C3: 0.075uF
>> 
>> I would quess C1 1.2uF
>> 
>> Any clues ?
>> 
>> J-Pierre
>> 
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