Parametric EQ

[aziltz]

Has anyone worked with this circuit from RG before?

http://www.geofex.com/article_folders/eqs/parmet.gif

He hints that 10k is too much resistance for a Q control, and I'm wondering if any one had success with other values?

[aziltz]

bump.  Hoping to find some general build advise or any comments really.

[welcomb]

Have been wanting to build a parametric EQ myself for the longest time too.

Can anyone help figure out how to calculate the sweep of Q with a 10k pot?

[aziltz]

Any discussion of Q or the cut/boost in dBs would be helpful.

[rosssurf]

Maybe this will help. I am trying to learn this stuff as well. I have to read over it several times before it sinks in(..can you say school for the gifted!)

Try these.

http://www.geofex.com/Article_Folders/EQs/paramet.htm

http://www.geofex.com/Article_Folders/EQs/paramet.htm#variable_fr_twin_t

[aziltz]

hey rosssurf!  that's exactly where I got the circuit snippet from, i should have linked to the article too.  It explains how to set the sweep ranges pretty well.  I'm using the most basic parametric design, implemented using FET Followers instead of opamps.

[welcomb]

Wow that's neat. I read that page about a year ago and the explanation of Q wasn't in there then.