[sdiy] tube filter topologies...

[Ken Stone]

Indeed the sallen-key type has been done. Check out  René Schmitz's site at
http://www.uni-bonn.de/~uzs159/

It is an interesting filter to build.

Ken 
 
At 07:58 AM 3/11/01 -0800, Nick Zuccaro wrote:
>
>hey there, i'm scheming up a tube LPF and am to the point where
>i'm checking out some topologies to see if they're implementable
>with tubes or not. one thing i'm leaning towards is doing a
>sallen-key type of filter, but this relies on having an op-amp
>type of gain stage. i've seen the schematics for the 2-tube
>opamps <philbrick/EB> and was wondering if anyone has acutally
>built one and done any characterization on this type of design.
>seems to work ok in theory, there won't be a whole lot of gain
>like the solid state opamps, but the bandwidth doesn't need to
>be very great for a lpf and there is very little external gain
>needed from the stage itself, so initally things seem to work
>out. i also checked out the schematic for eric's ts-3 tube
>filter, and that looks like it's a multiple feedback type of
>circuit. is this because the tube op-amp type of implementation
>is more of a science project than something that is actually
>realizable? i was just kicking around a few things and thought
>i'd see what other people have done previously...thanks, Nick
>
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Ken Stone   sasami at blaze.net.au  
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