semi parametric eq

[reap461]

Hi i am new so i hope i am posting in the right place can anybody let me know if they have any good semi parametric equaliser schematics sutible for midrange frequencies and if possible high frequencies but seperate eqs thanks

 

[coloradosound]

I built a 4 band parametric based on a design that came
from a company that was around in the 70's early 80's
that I believe I remember as Phoenix Systems? I think
they actually had an article in some mag like Popular
Electronics. It was based on TLO74CN Op amps. I think
it would be excellent to redo with modern chips such as
AD8620's, OPA2132's or 2134's, etc. I think the quad op
amps may be pin compatibe with the 074's. May require
a redesigned board for duals such as 8620's though.
If I can find that article or the schematic (20 moves since then)
I'll scan and post

 

[coloradosound]

As I recall the bands overlapped so that you could use
them and tune individually for lower and higher centers.
Also had adjustable Q!

 

[reap461]

thanks very much sounds interesting

 

[coloradosound]

I don't know where that article is, but I think it came out
of Popular Electronics or one of those other mags from
the 70's. The examples on this thread are very similar
to what I recal this one being like:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=26115&highlight=

 

[coloradosound]

This one is laid out even more similar to what I recall:

http://damien.douxchamps.net/elec/param_eq/

Even same opamp chips in dual version. I'd check pinouts
with those of newer amps listed above and use the
more modern chips.