What EQ bands do you guys like for guitar use?

[Brymus]

Almost there with the EQ project deciding on what bands to have,so I thought I would ask what you guys prefer from your EQs?
As is the 15k band is out, and 6Khz is the high band.
I am thinking maybe an 8Khz band,hence this thread.

Also what about having a clean boost after the EQ?
I seem to like this,but it would be less parts without one,I just finished looking over the Boss GE7 EQ
Do those band selections seem the most useful for guitar ?
Also doesnt it start with a small boost at about 2Khz before the EQ stages?

[petemoore]

  IF there's a 'constriction' elsewhere, such like the speaker does not produce 1 dern thing below say 200hz, having a bottom slider be adjustable is only a good way to waste current and amp factor between the speaker and amp.
  For the price of an EQ [15 buxx one day ~recently, new]...you can drop every slider, try the left slider ATWDown, the all the way up. If you can hear no difference what so ever, it is merely controlling the large or small currents [the ones that 'tax' the amp or bake the Sp coil] below what the speaker responds to...hence this one should be ATW rolled back for better amp/speaker life/same sound but better when you have the other sliders up [more amp power available for the ReLevant frequencies !].
  Then...controls...up to about 600hz, and you're into the 'relevant' frequencies, according to my post. Below this frequency it becomes very specifically notable as more dependant on the speaker/cabinet and maybe the amplifier what goes on down there...you have to get your pole out while in the river to tell how deep that gets to be. I've yet to see a typed relevant word IMEOpinion about these low frequencies in reference to just an EQ.
  We can assume the speaker is responsive above 600hz, and goes well up to at least 2000hz...this is where I would cluster EQ sliders more tightly to experiment with 'alternate densities'...how close the Hz and Khz numbers fall compared to the adjacent sliders.
  Some claim to need a 15 band, others 31, and while these will provide more specific frequency separation of 'adjacent frequencies', I would look at a parametric with some mods as an easier alternative that requires a bit more understanding to get what you want and doesn't show graphically what you have, can probably have the ability to provide the slopes/boosts and cuts where you want them...with a much simpler, less expensive build, +not slots to cut for sliders.
  The 15 bukk 7band EQ Behr***** makes is a fine EQ, worked exactly the same except lower noise than my Boss it was fashioned after, a good friend until I let him get melted.

[Brymus]

Yeah thats another consideration as well.
15 bucks will barely buy 7 pots and 7 knobs,thats not including shipping
Add a box and stompswitch,ect and you could easily buy 2 cheap mass made EQs
But wheres the fun/education/headache in that ?

[Mark Hammer]

I keep harping on about what you really need for a guitar EQ box.  And it goes like this:

1) A bass shelving control at around 160-200hz.

2) Two frequency-sweepable resonant boost/cuts (quasi-parametric).  These can be of varying parameters.  For example, you could have them both sweep over the same range, but have one set for much wider bandwidth than the other.  Or, you could have each with a moderate bandwidth and have only slightly-overlapping ranges (e.g., 200hz-1khz and 600hz-3khz).  The overlapping range  and wider bandwidth permits more complex adjustments to be made, where cut in one can overlap with boost in another at a different centre frequency.

3) A sweepable 2-pole lowpass filter with adjustable resonance to trim back the high end.  The resonance doesn't have to be continuously variable.  A 3-position toggle will do fine.

Those 3 boost/cut controls and 3 frequency adjustments will take you an awful long way with respect to redefiing the "character" of your instrument.

7, 10, 15, and especially 31 band EQ is for those instances when the manufacturer doesn't know which frequencies are important to you and provides many different fixed frequencies to tinker with, just to be sure.  Rooms may have multiple resonances that need to be compensated for.  EQ for creating a sonic character doesn't need that much complexity.  Its character is defined by how much oomph, where the top-end ends, and a couple of resonances or dips.

[BubbaFet]

I keep harping on about what you really need for a guitar EQ box.  And it goes like this:

1) A bass shelving control at around 160-200hz.

2) Two frequency-sweepable resonant boost/cuts (quasi-parametric).  These can be of varying parameters.  For example, you could have them both sweep over the same range, but have one set for much wider bandwidth than the other.  Or, you could have each with a moderate bandwidth and have only slightly-overlapping ranges (e.g., 200hz-1khz and 600hz-3khz).  The overlapping range  and wider bandwidth permits more complex adjustments to be made, where cut in one can overlap with boost in another at a different centre frequency.

3) A sweepable 2-pole lowpass filter with adjustable resonance to trim back the high end.  The resonance doesn't have to be continuously variable.  A 3-position toggle will do fine.

Those 3 boost/cut controls and 3 frequency adjustments will take you an awful long way with respect to redefiing the "character" of your instrument.

7, 10, 15, and especially 31 band EQ is for those instances when the manufacturer doesn't know which frequencies are important to you and provides many different fixed frequencies to tinker with, just to be sure.  Rooms may have multiple resonances that need to be compensated for.  EQ for creating a sonic character doesn't need that much complexity.  Its character is defined by how much oomph, where the top-end ends, and a couple of resonances or dips.

Can you kindly point me to any schematics that implement what you espouse? Thanks!

[WGTP]

Mark definitely has the right idea.  One of my thought on the matter is that speakers are under appreciated for their contibution to the tone.  Most 12" guitar speakers have a peak around 3.5kHz and a dip at around 1.6kHz of varying size and width.  Then around 800Hz, 400Hz and 200Hz there are smaller variations.  Those are the frequencies I see as being important...   

[Brymus]

Thanks for the feedback Mark,Pete ,and WGTP
I agree the idea Mark gives would be more advanced,with better control over shaping ,and less knobs.
It would also be kinda difficult for some giggers to understand outside the low end control and 3 way high switch.
Not to mention my filter grasp doesnt include the skill needed to design such a box...

I have calculated the center frequency for several different resistor values using standard cap values.
And will make a chart and post it with the final EQ design.
I also thought to make the layout for 10 or more bands.
In a way you can just erase the bands you dont want with out effecting the design,sort of like a snap off razor blade/box knife
Then people can pick their frequencies and number of bands and build accordingly.