parametric equalizer question

[nonoxxx]

I recently modified a boss metal zone to get an overdrive with the metalzone EQ , and I was really satisfied by the result so now I am putting it on stripboard to make a pedal.

But I was looking also at the schematic of the one band parametric EQ of musikding, It seems that it make something close, but the  opamp that will boost the mid level is non inverting , instead of inverting for the metal zone ( the mid pot).

Someone can explain me the difference for this application ?

Here is the mt 2schematic : http://www.hobby-hour.com/electronics/s/schematics/boss-mt2-metal-zone-schematic.gif

and the 1 band parametric EQ of Musikding :
http://diy.thcustom.com/?wpdmdl=3229

Thanks,

[samhay]

Give this a read:
http://www.geofex.com/article_folders/eqs/paramet.htm

[nonoxxx]

Thanks, but it explain how gyrator work I don't find information why U1b on this circuit is used as inverting and not non-inverting

[samhay]

Look again at the Muskiding schematic. IC1B is set up in the same was as the geofex article.

The way the mix op-amp works is described as:

'The [mix] pots are connected between the inverting and noninverting inputs of an opamp. The opamp also has input and feedback resistors.
Effectively, the wiper of each pot is grounded through the low impedance of the LC filter at that frequency.
The pot wiper may be dialed to the [non-inverting] input side, in which case it shunts the input to ground, producing a notch in the frequency response at its center frequency.
It may also be dialed to the inverting input, which shunts the feedback to ground at its resonant frequency, producing a peak[.
W]hen directly in the center, there is no effect from the LC filter at all - frequency response is flat. In this position, the LC filter's effect is equal on both + and - inputs, so there is no overall effect.'

[nonoxxx]

Thanks a lot so if I understand correctly , for a mid control that is flat at 12 o clock I must use the same as the metal zone : pot connected on the inverting input  so at center it will do nothin g and boost when turned clockwise and cut turned counter clokwise

[nonoxxx]

But on the article I i don't understand the word notch in an electronic/ music context

[Hatredman]

Google "notch filter"


--
Scarlett Johansson uses a Burst Box with her Telecaster.