Equalizer Q value

[caspercody]

Hello

I am building a 5 band EQ with same controls as a Mesa Mark amp. I am using the board I got from PedalPCB, and changing values using AMZ FX gyrator calculator.

My question is, for the Q value, does this need to be a small or large number? Or does it really not matter?

Thanks
Rob

 

[jwin615]

Here are someone's simulated/calculated actually frequencies and q values. I assume they are fairly accurate but have no confirmation.
Yes, q values matters. Too narrow or a q and it sounds like a cocked wah. Too wide and it will overlap the other bands too much.

 

[caspercody]

Is there a window to try and get the Q value into?

 

[caspercody]

Thanks for the link!

 

[jwin615]

It depends on the design and intention. If you want it to sound like a mesa, I'd target near the q values of the previous link. Maybe Google around and see if others have published similar analysis.
But a few quidelines

~0.7 will still sound natural and cover close to 2 octaves. Be careful not to cramp other bands.
1.4 will cover about an octave
(So at 1k it will boost between 500hz and 2k, centered on 1k)
2.5 and above will start sounding sharper.

You have to take into consideration the other band's center frequencies and Q. It's fine to have some overlap but you don't want a lot. Can get weird phase smearing if that happens.
Also, an octave at 5k will feel more narrow than an octave at 250hz
The mark eq is about a 3 octave eq(freq triples between each band)
3 octaves is a q of a out 0.4 so I would stays above that.
There are some handy charts here
If you have access to basically and digital parametric EQ with a curve readout, plug your points and Q.values in and it should give you a decent look at spacing and overlap.
In this scenario, I'd stay between 1.4 and 0.4 or 1-3 octaves.