Slider Pots for a graphic eq

[DVB_master]

Hello, I have found some slider potentiometers (10K audio).
I'm planning to use them in a such equalizer (If you check my old posts, maybe you'll find it).
They are logarithmic pots. Now here's my question: Is it a good idea to use them to control the bands of the eq?  Or should they be linear pots so that when the metal lever is in middle position the the resistance is equal from 1 to 2 and from 2 to 3 (5K and 5K)?
Thanks!!!!

[DVB_master]

Another information: the potentiometer I have are stereo slider pots, 10K log.
Is there any way to make them linear? If this is not possible, what can I do to use audio pots in an equalizer circuit (like boss ge-7)?
Any help very appreciated!

[Mark Hammer]

It IS useful to have linear pots that can potentially show the midpoint of boost and cut and provide equal "dialability" on each side.  On the other hand, do we use every single band the same way, and require equal diability of boost and cut from bottom to top band?  Not really.  Most of us will use the lower bands to control honking, but the mid and upper bands to add some bite. 

Consequently, what you might consider is to flip some of the pots around so that they are used in a sort of "anti-log" manner.  For all their weak points, one of the nicer properties of slider pots is that they can be turned around 180 degrees to reverse non-linear tapers without changing the way the user uses the control.  For those bands where you want to have finer control of cut and only occasional less-nuanced use of boost, orient the pots one way, and for those bands where you want finer diability of boost, flip 'em around.

Of course you lose the ability to set all controls to some arbitrary midpoint and know that things are "flat".  But if you have a bypass switch to restore flat response, who gives a hoot anyways, right?

[DVB_master]

Nice tip! So, there's no way to make them linear? Since they are stereo pots, may I combine in a such way the two tapers? The graphic line of an equaizer pot is similar to an "S", in the middle of the S the resistance is Rpot/2 and the slider is at center position, above the middle point the audio increase in a log way, and below in an anti-log way. Can I obtian that?
If nothing is possible, I think I'll follow your tip,Mark, that's maybe the best thing to do  !

[DVB_master]

Hi, I have read and understood with the help of geofex and math, how potentiometers work.
Only a question: the band control of an equalizer, is given by the voltage division ratio between Ra and Rb (Ra+Rb = Rpot) or by the resistance value (5k, 3k, 10k)?
If I put a 1,2K resistor in parallel with the 10K log potentiometer (in order to have Ra/Rb = 1 at the middle of the slider), I obtain this curve.
At middle rotation, Ra = 1K and Rb = 1K, so Ra/Rb = 1. In the original schematic Ra/Rb is also equal to 1, but Ra = 5k and Rb = 5k, does this affect the job of the potentiometer in the band control?



What do you think about?

[DVB_master]

let me explain better  : are the potentiometers in an equalizer used as voltage dividers? If yes (as I think), can 1k or 2k pots be used in place of the 10K ones (for band control)?