# Need 13 Band EQ Step Formula



## Swaglife81 (Oct 15, 2016)

I think the title is the correct title. When searching EQ forumulas I'm only seeing 10-11 band or 31 band formulas. I have a Pioneer X2800BHS with a 13 band.

What I'm looking for is the formula used for 13 bands of EQ. Pioneer usually goes from 50 - 80 - 125 - 200 and so on. What I want to know is when boosting or cutting let's say 50 is it 50 and below equally or is it split with the next frequency that's 80 so would bumping 50 go up to the halfway point in between 80 boosting to 65. And the 80hz boost ING or cutting starts with 65,66 and up. I don't have experience a DSP, gonna tune what I can with crossover, slopes, and graphical EQ. I'll use my ear first and try RoomEQ or some type of software to see what I'm hearing. I've searched everywhere and see different EQ steps like Kenwood starts at 60 or another brand starts at 30. Hope this makes sense what I'm asking for. I obviously know a 31 band L/R EQ is much better. I want to crawl before walking and I think I can get a great user experience for starters without going DSP just yet. I have a full build in front of me as soon as I find the raw 6.5's I want that are actually in stock (TM65 or Dayton DSA175, etc etc.


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## Hillbilly SQ (Jan 26, 2007)

Best way would be to do the install and then boost and cut each frequency with rta going. At least that's how I would do it to find out how it's set up. I've put thought into this and this is one of the reasons I don't like graphic, but they're great for nudging the tonality curve after the main tune is done with an outboard dsp.


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## fcarpio (Apr 29, 2008)

Hillbilly SQ said:


> Best way would be to do the install and then boost and cut each frequency with rta going.


You can buy something like this for 15 bucks:

Dayton Audio iMM-6 Calibrated Measurement Microphone for Tablets iPhone iPad and Android

Then download an app like this one:

https://play.google.com/store/apps/details?id=radonsoft.net.rta&hl=en

Then do what Hillbilly SQ is suggesting.


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## Justin Zazzi (May 28, 2012)

The graphic equalizer will effect the center frequency the most (80hz in your example) and it will also effect frequencies above and below the center frequency. The amount of cut or boost to adjacent frequencies will reduce the further away from the center frequency. So 81hz will be changed just about the same as 80hz will be, but 100hz or 63hz will be changed much less so. The frequencies above and below the center frequency are adjusted equally in this regard.

Each frequency band has a property called Q which describes how wide or narrow the band is, which effects how much the adjacent frequencies are effected. A smaller Q means a wider band, which is what you will find in equalizers will less bands to choose from (like a 7-band, or in your case a 13-band). An equalizer with many bands to choose from, like a typical 31-band, will have a larger Q for each band meaning each band will effect only the close neighbors (in this case, a 31-band equalizer usually has a Q just slightly above 4.0).

If you adjust two bands that are adjacent, such as the 80hz and 100hz bands, then the effect of both bands will overlap a little bit. Also, a graphic equalizer is one where the frequencies and Q values are preset and not adjustable. A parametric equalizer means you can change the center frequencies and the Q values to get much more precise control (but also infinitely more ways to get it wrong if you're not sure what you're doing).

The last minute or so of this video shows what a 31-band EQ looks like when you adjust the 80hz band (starting at 9:33)

https://youtu.be/DKdpOLh78SU?t=573

Does that help?


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## Swaglife81 (Oct 15, 2016)

Appreciate it guys. Helped alot, sadly I wish there was a exact type of formula one could see.


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## Justin Zazzi (May 28, 2012)

What sort of formula are you looking for? Do you want some equations or math that describes this?


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## Jepalan (Jun 27, 2013)

Swaglife81 said:


> I have a Pioneer X2800BHS with a 13 band.
> 
> What I'm looking for is the formula used for 13 bands of EQ. What I want to know is when boosting or cutting let's say 50 is it 50 and below equally or is it split with the next frequency that's 80 so would bumping 50 go up to the halfway point in between 80 boosting to 65.


Your EQ conceptually consists of 13 constant-Q bandpass filters centered on each band's frequency. 'Constant-Q' means the bandwidth of each filter is constant regardless of the amount of boost or cut.

Your manual spec's the EQ like this:
Frequency: 50Hz, 80Hz, 125Hz, 200Hz, 315Hz, 500Hz, 800Hz, 1.25kHz, 2kHz, 3.15kHz, 5kHz, 8kHz, 12.5kHz
Gain: ±12dB 2dB step

We cannot provide an exact formula without knowing what the 3dB BW and filter-order of your EQ is. 

This pic is not your EQ, but it gives you a general idea of how the filter responses overlap...


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## Justin Zazzi (May 28, 2012)

That's a great picture to show the overlap. Where did you find it? I was hoping to share something similar but couldn't find such a thing.


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## soundstreamer (Jun 2, 2015)

That's some helpful information as I will probably doing the same thing the OP is doing. I have the same head unit and want to adjust it as best I can until I get a DSP. Since I'm going active as well would it be good to set the output level of each speaker still or will that matter much? I'm new to this so I hope it's not a stupid question.


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