Germanium Diode Filters?

[Duane R Balvage]

        Hello all -


         Thanks to all that replied yesterday on my query about 

      the EMS diode ladder filter. I got it working correctly

      last night, and, remembering this discussion on substituting

      germanium diodes in the ladder section got me thinking ...

      - so I ran down to Radio Slack, and picked up some 1N34A

      germanium diodes, and put them in the filter.

       - To make a long story short, THIS FILTER IS GOING IN 

      MY KORG 770 MODS!!! It sounds great! Of course, the original

      Silicon version sounded pretty good, but it sounds, uh,

      "sproingier" i guess :-] . Without the resonance turned up,

      it is very smooth sounding, but turn up that resonance and

      WOW! 

        Other mods I did to it that I like was a 1M pot for resonance,

      and arranging the cap/diode ladder like this:



                      |          |
                     ---        ---
                     \ /        \ /
                   -------    ------- 
--                    |          |
                      +----||----+
                      |          |
                     ---        ---
                     \ /        \ /
                   -------    -------
--                    |          |
                      +----||----+
                      |          |
                     ---        ---
                     \ /        \ /
                   -------    -------
--                    |          |
                      +----||----+
                      |          |
                     ---        ---
                     \ /        \ /
                   -------    -------
--                    |          |
                      +----||----+
                      |          |
                    | /          \ |
                    |/            \|
>---||----/\/\/\----|              |----/\/\/\---||----> out         
                    |              |
                    |\            /|
                    | \|        |/ |
                      --        --                                            
                         |     |
                         +-----+



        -one other thing ... replaced the 741's in the signal path

    with NE5532's.


      So, anyways, it sounds real nice, and, we were all correct in 

    assuming it would sound different! Try it - you'll like it!


                         on to next projects ...

                                                 Duane
 
         
  "Two nothings is nothing, thats mathematics, son...." - Foghorn Leghorn  
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