# 6-Band EQ for BASS



## IPv6Freely (Aug 25, 2021)

I want to use the 6-band EQ for bass, but I assume the frequencies chosen are more treble-specific. What would you guys recommend changing to make this thing bass-friendly?


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## brokenwizard (Aug 26, 2021)

This is a good page to check out. If you know the frequencies you want to affect. Maybe take a look at the Boss Bass EQ and similar for starting points for the kind of frequencies. If you have an audio interface you could mess around with a parametric eq on there with your bass and sweep around frequencies of interest.






						Guitar Pedals: Gyrator Filter Calculator
					

Calculate freuqency cutoff for guitar effects pedals with vacuum tubes and solid state electronics. FREE calculator.




					www.muzique.com


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## brokenwizard (Aug 26, 2021)

I really wish there was a reverse calculator where you enter the frequency and q and it tells you the component values.


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## Feral Feline (Aug 28, 2021)

For reference, Boss Hz:


GE-71002004008001k63k26k4GE-7B (Old)621252505001k2k4kGEB-7 (New)501204005008004k510k

I'd recommend the earlier GE-7B's range, but your needs may be different than mine.


For reference, from TH Custom's EQ docs:

*BASS*

*RESISTER**CAP 1**CAP 2**Hz**Q*250k220n47n14410250k100n22n31310100k330n47n1865

*MIDS*

*RESISTER* *CAP 1**CAP 2**Hz**Q*120k86n33n40010100k47n22n7221068k33n22n10451068k220n22n400447k150n15n715368k68n10n1080468k68n8n212004

*HIGHS*

*RESISTER**CAP 1**CAP 2**Hz**Q*47k33n4n72700447k47n2n233332

*Q above —* (3=oct, 10=quarter oct)*






						6 band EQ mods for bass?
					

Building the 6-band EQ and wondering about mods to make the bands a little more bass-friendly... maybe take band 1 down to 50Hz etc. Any suggestions based on cutoff frequency calculation for the filters?




					forum.pedalpcb.com
				








						6 Band EQ formula?
					

So, let’s say I wanted to change the frequencies on some of the pots for the 6 band eq. What would be the formula if I wanted to use a freq that’s higher or lower?




					forum.pedalpcb.com


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## IPv6Freely (Sep 1, 2021)

Can you explain what "Q" is?


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## Feral Feline (Sep 2, 2021)

What or who?

What: Gadget development branch of MI6

Who: The head of the gadget development branch of MI6


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## Feral Feline (Sep 2, 2021)

IPv6Freely said:


> Can you explain what "Q" is?


Q is the width of the frequency you're modifying.




Image courtesy of HomeTracked (link below).

It's oft said to cut narrow, boost wide — but really it depends on what you want to do with the EQ overall.

A wide Q affects the surrounding frequencies of the centre-freq band more than a narrow Q of same.

If you're fighting feedback, you'd want to cut the offending frequency without attenuating the fine upstanding freqy citizens surrounding it — so you use a narrow Q.

Wide EQ is probably better for a project like this 6-band, but too wide and the EQ ranges on either side of the freq you're adjusting get affected as well. A little overlap is okay, even desirable to some.


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## IPv6Freely (Sep 2, 2021)

Feral Feline said:


> Q is the width of the frequency you're modifying.
> 
> 
> 
> ...


First, let me say that I love that you reply with one BS reply and then follow it up with a real one 

Okay, I get it, I think. So, instead of cutting 100Hz and ONLY 100Hz, you cut 100Hz and a certain amount above and below that value. Is that right?

EDIT: Just read the article. Awesome! And it seems lower Q numbers means a wider cut/boost. Can you tell me if my understanding of how Q is derived is correct?

Eg. 220Hz is an A. That means 440Hz and 110Hz are also A. As you mentioned above, Q3 = octave and Q10 = 1/4 octave

Therefore if you cut 220Hz w/ Q3, you are cutting everything from 110Hz to 440Hz (but not equally because it's a wave)?

And if you cut 220Hz w/ Q10 you are cutting everything from 192.5Hz to 247.5Hz? (1/4 of an octave for an A is 27.5Hz)

Do I have that all right?


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## Feral Feline (Sep 2, 2021)

Pretty much, although my understanding is that the octave for Q3 is centred around the peak of the wave — what you've described is a two-octave range surrounding the peak.

So, to use your A220Hz example, the peak would be right at 220Hz, while the troughs of the wave on either side would be midway betwen 110Hz and 220Hz, and again midway between 220Hz and 440Hz.

A quarter of an octave is on a sliding scale, so when you say "1/4 of an octave for an A is 27.5Hz", that's only true of A2 (110Hz). A quarter of A4 (440Hz) is going to be 110Hz. https://en.wikipedia.org/wiki/Piano_key_frequencies

If you cut 220Hz with a Q10, I'm not sure of the exact frequency range being cut on either side of the peak as I don't know the math involved to calculate it, but suffice it to say you've got the overall gist — a small number Q has a wide range with a soft peak, and a large Q# has a narrow sharp-peaked range; whether sharp or soft Q, the further you get away from the peak, the less affected the surrounding frequencies.


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## IPv6Freely (Sep 2, 2021)

Feral Feline said:


> Pretty much, although my understanding is that the octave for Q3 is centred around the peak of the wave — what you've described is a two-octave range surrounding the peak.
> 
> So, to use your A220Hz example, the peak would be right at 220Hz, while the troughs of the wave on either side would be midway betwen 110Hz and 220Hz, and again midway between 220Hz and 440Hz.
> 
> ...


Oh, I got it. 1 octave centered on the frequency you're adjusting. 

And yes, I should have specified 1/4 of A2 and not just "an A" 

I get it now, and this will help a ton. I'm going to breadboard this thing to dial in what I like. Thank you for the help!


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