i mapped out some EQ settings in a new box design.  9 cubic feet with a 32 hz tuning and 128 port area. Fi audio SP4 18 on a ZX2500.1

this is my first time ever looking into any EQ or using win isd to this level. im sure most of you will remember that my goal here is to get a flat responce curve with as few peaks as possible up into the 65hz range for the music i like.

 

am i on the right track here?

 

 

a gain of 3 db @ 65hz

a static gain of 2db across the system

a gain of 3db at 32hz

a gain of -3.5db at 38hz

a gain of 2db @ 50hz

xover at 100hz

sub sonic at 28hz

air velocity is 20m/s

impedance does not drop below 3.6ohm while inside of xover frequencies.

 

max VA is 4KW @ 61hz in a very sharp peak so there may be a bit of clipping there.

 

nominal VA is 2800

 

maximum cone excursion is 30mm

 

my 31 and 60hz are the same volume with a smooth roll between them

 

you need to RTA the vehicle first before you know what you need to model for

ok, how shall i do this?

If you are serious about this, we are a manufacturer of measuring devices.

 

www.spllabusa.com

 

You would need the RTA Pro which Maps just over $300 in the USA.

ok so i think i need a real DB meter. i have an omni directional yamaha mic already that i think ill try and use and i found a program called REW that i will use to set a base test in the truck. 

 

when measuring output does it matter how the speakers are setup? should i use the setup i want in the final config? should i use all sealed? should i use all IB?

use as normal.  The adjust EQ settings as needed.  We do not perceive frequencies in a linear fashion so your curve on paper will more than likely not be perfectly horizontal  

In general you don't want gain either, just cuts. As with anything general there are exceptions, but don't start with so much gain. Also realize that you can have a fair amount of ripple and have it not be noticeable.

ok, so ill start with cutting to flatten, from there can i gain across the entire spectrum to bring the volume back up? say amping the line voltage form 4 to 6v?

ok, so ill start with cutting to flatten, from there can i gain across the entire spectrum to bring the volume back up? say amping the line voltage form 4 to 6v?

 

All that's going to do is allow you to turn the gain down on the amp.

 

The gain is not a volume control.

 

Unless the input voltage is so low or near so low that audible noise is introduced into the system, a line driver is not necessary.

well any EQ i pick up will have a line driver on it so that's what i was thinking of. in either case. as i reduce the db on certain frequencies to flatten things out i would want to boost the over all volume up so im not putting 50% power to the sub. how should i do this?

if you are afraid of the SQ part of the front stage not keeping up with your sub(s), then you need more cone area, power or different drivers used for such purpose.

 

However, higher efficient drivers like PA or even horns would still need EQing for the same purpose you are wanting to do.

Then once that happens.. how less loud is it then?  I do not know.. 

 

It's trial and error.  If your front stage ends up not being enough.. then add or change.  

 

You can always turn the volume down on the sub(s) in such cases where Sq is more important than SPL.

i think my question is more general and maybe im not thinking of it correctly.

 

lets say ive got a sweep now of 30-50hz.   32hz is 8db, 40 is 14db, 50 is 10db.  so i start cutting gains to even it out so all 3 of these frequencies are around 8db on teh graph.   now lets take 40hz; lets say the amp was putting out 3KW at 40 and the sub was moving 95% of xmax. as i remove 57% of the volume of this through the -6db EQ setting lets say the amp is putting out 1290w and the sub is moving 40% of its xmax.

 

how do i bring the amp power back up with the flattened EQ so that the sub is utilizing its full power and also that the sub is putting out close to its full power.

 

am i thinking of this right or wrong?

the problem with your math is no matter what you EQ, some frequencies or ranges will not be effected!

 

Therefore they will remain unattenuated.

 

When speaking about EQ, no not mix power with dB.

 

Focus only on dB about this topic.

 

So in saying that, you need not worry about "amping" the overall response range back up.

ok, i wont try to wrap my head around that yet. now i need to find the EQ thats right for me

If you reboost you will be overdriving.

Going to need a serious proc that will get younin way over your head if you try to implement what you have. Just focus on fixing your box and then use your ears.

im going ot need an EQ tho right? i should fix the box and then EQ it

No, fix the box first then listen to it.

but i want an EQ

 

im not confident this box is salvageable. i shall see but i dont think i can change the tuning with out loosing a fair amount of internal volume.

Let the bass play for some times. Then you'll know what you need to do...or not !

If it's not broke, why fix it ?

ok so i will put my current box into a program and see wher eits at, i think i will design a new box here and rebuild it as i think i want to go from 7 to 9 cubic. its what winisd is telling me to do anyway

but i want an EQ

 

im not confident this box is salvageable. i shall see but i dont think i can change the tuning with out loosing a fair amount of internal volume.

Eq's only make things worse unless you know what you need to fix with them. Once you know that it is easy to shop for one as well as you will know what you need.

WInisd is not going to dictate what your box will do in your vehicle.  

The cabin environment will alter many things.

 

And increasing volume that much is going to make it focus more on the low end and lose even more upper end.

winisd clearly showed that raising the box volume would move the sub into a 30hz low end, flatten the curve out a bit, and allow the sub to hit 64hz the same as 30hz.  from what i understand box volume does not effect notes but rather only effects how much power the sub needs to reach xmax.

 

can you fill me in on areas that i do not understand?

You are ignoring the transfer function of your car, ie cabin gain. In situ measurements are required to understand that.

Did you follow the manufacturers recommendation at all when you built your box?

yes, when i built my current box i pulled up the cut sheets that FI has on here and used the same port area. i also kept it around the same cubic footage +/- .2.

 

ok so here is what im not quite following: the specs on the sub are input into winisd and that will tell me how the sub will handle power and how it will reproduce sound. so it tells me the air speed at the port, tells me the rough frequency curve not factoring in cab gain, and how much power the amp is using. so from that information i design a box to the proper size specs. now the box that Fi has on there cut sheets and the basic math i do shows about the same port area, but when i use the programs online it gives me a min port area of 3X that amount. now my air speed is about 20f/s so thats WAY below what people say to max at so perhaps i have to much port area?

 

secondly if i build my box factoring in cabin gain and using winisd and ignoring factory specs would my box not be better than the factory boxes?

 

finially: I am not certain i fully understand how cubic volume effects things. when i had a box build years ago i was told that it would be great with high range 40hz area, but if i wanted it to reproduce lower range i would need to build it bigger so it had more cubic footage to reproduce the sound. when watching videos online about box building i see people say "this sub is recommended 7-8 cubic so im going to give it the full 8 as i want more frequencies to be reproduced".  

 

I have asked on here, 12v, and smd at various times and in various ways how cubic footage effects things. i have never been told that the size of the box will effect the frequencies it can reproduce and yet this very concept seems to be referenced by those who build boxes.

 

what am i missing?