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10" Subwoofer simulation graphs - please add your suggestions

Naveenbnc

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#1
Hello all... I am going to build a 10" ported subwoofer.
I will share the simulation results and request you all to add your suggestions.
Since I have many details, I will share one after the other, so that it will be easy.

The very first question is related to "SHAPE" of the graph.
Is that peak in RED graph at 50-70Hz good for a subwoofer?
Or a gradual smooth curve (yellow) is good?

It is clear that yellow has a better low end extension. But I am not concerned about the numbers now.
I just want to know if peak in the graph is good or not.
Purpose of the sub is for Movies primarily.
Any suggestions please .... I will share graphs for different box volumes, and different port sizes later

Regards,
Naveen

10 inch sub iwai_1.JPG
 
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elangoas

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#2
Hello all... I am going to build a 10" ported subwoofer.
I will share the simulation results and request you all to add your suggestions.
Since I have many details, I will share one after the other, so that it will be easy.

The very first question is related to "SHAPE" of the graph.
Is that peak in RED graph at 50-70Hz good for a subwoofer?
Or a gradual smooth curve (yellow) is good?
What is the difference between Red Vs yellow?.. Ported Vs sealed?..

Not considering sealed subwoofer?..
 

elangoas

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#4
both graps are for the same ported sub only. with variation in box size and port size etc.
As per specs, this driver is more suitable for ported box. :)
I have no experience reading simulation response.. But, i guess the yellow line is preferable as it has linear response without any spikes..
 

Naveenbnc

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#6
i can push the roll off point towards the right side by manipulating the box size etc.
My only doubt at this moment is the "little peak" Vs "gradual slop" which is better for a subwoofer
 
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#8
Balance target SPL, low end response (-3dB) ( without exceeding driver xmax) and with reasonable input power. Arrive at whatever box volume/port size the simulation suggests. Avoid too long port by choosing larger box volume and avoid port compression by using not so small port.

The simulations are free field response only, they tell what the sub produces. What sub produces and what the listener hears are very different things at sub frequencies. Bass is completely dominated by the room modes (peaks and nulls). The bass waves hit multiple walls before the ear can detect them. Every room is different. Eq is a must. The free field response will be swamped by the room. At bass, we hear the room more than the sub
 
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Naveenbnc

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#9
Two different roll off points in my first picture is creating confusion may be.

Lets take the below sketch for comparison.
Both graphs are within +/-3dB. One is smooth and the other has a peak.

So which one is better for a subwoofer is my doubt.

Screenshot_2018-11-08-13-16-43-874_com.miui.gallery.jpg
 

Naveenbnc

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#13
Balance target SPL, low end response (-3dB) ( without exceeding driver xmax) and with reasonable input power. Arrive at whatever box volume/port size the simulation suggests. Avoid too long port by choosing larger box volume and avoid port compression by using not so small port.

The simulations are free field response only, they tell what the sub produces. What sub produces and what the listener hears are very different things at sub frequencies. Bass is completely dominated by the room modes (peaks and nulls). The bass waves hit multiple walls before the ear can detect them. Every room is different. Eq is a must. The free field response will be swamped by the room. At bass, we hear the room more than the sub
thank you very much for the inputs .... :) I learned that my room, sub placement, etc etc will decide what I actually hear.

As a starting step to design a box, these simulations are the only option I have.
(I really love to have the formulae to decide box size and port size though .... :confused:)
As you said.... I will focus on where I am getting the low end @ -3dB ....
Just curious to know....which freq response curve is better for a subwoofer.... little peak Vs gradual slope ...
 
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#14
Gradual slope.

Once you have your box volume, tuning frequency and port dia, the simulation tool will tell you the length of the port needed.
Use 2.5" as port dia and see the results in simulation.
 

Naveenbnc

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#16
Ok.... I did some trails with simulation for two different box sizes.
One is compact, and the other is big.

In any case the best F3 i could achieve is around 30Hz with this driver.
(we can push the F3 down to 26Hz ....but the box size is very large...)
Im sharing the graphs .....

YELLOW graph is for small box (32L internal volume)
GREEN graph is for big box (62L internal volume)

I used a rectangular vent for now ....
With a round vent, I am unable to control vent air velocity below 18m/sec
I have to try further ....

10 inch sub iwai_3.JPG
 
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Naveenbnc

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#20
Vent air velocity is kept under 18m/sec
And in the DB-SPL graph, i struggled to make sure the dip (between 50 to 90Hz) doesn't fall below -3dB line.

I don't know how to judge if the phase response graph is good or bad, and how it effects the SQ.
Group delay for the bigger box is greater than 24 msec/Hz. I don't know if that is a bad sign ....

Any suggestions and comments are appreciated .... :):)
 
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