semi parametric eq

reap461 · 27th October 2008, 02:23 PM

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 · 27th October 2008, 05:26 PM

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 · 27th October 2008, 05:29 PM

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 · 27th October 2008, 06:48 PM

thanks very much sounds interesting

coloradosound · 4th December 2008, 08:40 PM

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:
Parametric Schematic

coloradosound · 4th December 2008, 08:56 PM

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.

27th October 2008, 02:23 PM	#1
reap461 diyAudio Member Join Date: Oct 2008	semi parametric eq 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

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27th October 2008, 05:26 PM	#2
coloradosound diyAudio Member Join Date: Nov 2005 Location: colorado	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

27th October 2008, 05:29 PM	#3
coloradosound diyAudio Member Join Date: Nov 2005 Location: colorado	As I recall the bands overlapped so that you could use them and tune individually for lower and higher centers. Also had adjustable Q!

27th October 2008, 06:48 PM	#4
reap461 diyAudio Member Join Date: Oct 2008	thanks very much sounds interesting

4th December 2008, 08:40 PM	#5
coloradosound diyAudio Member Join Date: Nov 2005 Location: colorado	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: Parametric Schematic

4th December 2008, 08:56 PM	#6
coloradosound diyAudio Member Join Date: Nov 2005 Location: colorado	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.