I need some help, comparing results WinISD vs BassBox vs WinISD Pro, why ???

[mledez]

Hi,

I decided to change my sub (Image Dynamics ID12D2 V3), So I bought Focal 40 V1 16" Driver...

Taking a look at the user manual I noted the suggested aplication values.. All number in liters and Hz

Fast and Tight Bass 40L Fb 25 F3 46
Punchy and Dynamic Bass 50L Fb 23 F3 43
Deep and Articulate Bass 60L Fb 20 F3 40



So I decided to check the curves and make some changes to create my new box... But WTF

The curves in WinISD are exactly ass focal but BassBox and WinISD Pro show me something very rare

What's happening???

The green line is my model

WinISD


Yellow 40L Fb 25 F3 46
Blue 50L Fb 23 F3 43
Red 60L Fb 20 F3 40
Green 62L Fb 34 F3 39

WinISD Pro


Yellow 40L Fb 25 F3 61
Blue 50L Fb 23 F3 56
Red 60L Fb 20 F3 52
Green 62L Fb 34 F3 54

BassBox Pro


Yellow 40L Fb 25 F3 67
Blue 50L Fb 23 F3 59
Red 60L Fb 20 F3 55
Green 62L Fb 34 F3 58

Please give me a hand!!! What do you think?
Don't look my english

[talnlnky]

YES!... a fellow box modeler...

I started using ISD Pro, then got my hands on BBP 6.
TRUST BBP, ISD though fairly good, isn't as good as BBP. Though, BBP is much more technical.

On with your problem... I might get around to actually modeling this up myself... I dunno, can't promise anything. Its been awhile since i've done much box designing/modeling, but I believe the problem is the box size.

Focal is saying to go ported on that 15/16" sub with 40-60L. There are two big clues that state that the sub probably needs a bigger box tho. Check out the values for Vas, and Qts.

That Vas tends to say "decent sized box"... and generally the higher the Vas, the bigger the box you need.

The Qts kind of gives you a clue as to how big, or small of a box it needs, the lower the value, the smaller the box. Its most often used to determine what kind of box because it has to do with the suspension & movement properties... but generally the small the number the smaller the box (comparing ported to ported, and sealed to sealed of course). That Qts shows your sub as being boarderline ported/sealed box optimized. If you had a value closer to say .30-.35 i'd be more willing to believe that your sub is meant for small 40-60L boxes.


SO!.... what I want you to do, is to model those boxes up again, and then change one of the boxes to 100L/FB 35, and then do another to 150L/FB 35. See what happens to the frequency response. I bet the bottom end really fills out.


If it does, let me know, and i'll explain what most likely is going on.


EDIT: when I talk about "big box" or "decent sized box" I mean relative for a 15" sub. obviously any box for a 15" will be big, even a sealed box.

[mledez]

Originally Posted by talnlnky

YES!... a fellow box modeler...

I started using ISD Pro, then got my hands on BBP 6.
TRUST BBP, ISD though fairly good, isn't as good as BBP. Though, BBP is much more technical.

On with your problem... I might get around to actually modeling this up myself... I dunno, can't promise anything. Its been awhile since i've done much box designing/modeling, but I believe the problem is the box size.

Focal is saying to go ported on that 15/16" sub with 40-60L. There are two big clues that state that the sub probably needs a bigger box tho. Check out the values for Vas, and Qts.

That Vas tends to say "decent sized box"... and generally the higher the Vas, the bigger the box you need.

The Qts kind of gives you a clue as to how big, or small of a box it needs, the lower the value, the smaller the box. Its most often used to determine what kind of box because it has to do with the suspension & movement properties... but generally the small the number the smaller the box (comparing ported to ported, and sealed to sealed of course). That Qts shows your sub as being boarderline ported/sealed box optimized. If you had a value closer to say .30-.35 i'd be more willing to believe that your sub is meant for small 40-60L boxes.


SO!.... what I want you to do, is to model those boxes up again, and then change one of the boxes to 100L/FB 35, and then do another to 150L/FB 35. See what happens to the frequency response. I bet the bottom end really fills out.


If it does, let me know, and i'll explain what most likely is going on.


EDIT: when I talk about "big box" or "decent sized box" I mean relative for a 15" sub. obviously any box for a 15" will be big, even a sealed box.

Wow... You give me a lesson for free

Anyway the problem was a wrong value in field inductace... The graph now show something very similar to focal sheet

Thanks for your help.

I also decided to model again the boxes and this time decided to take a look at the sugested High Output Box that BBPro have and surprise

Is a 62L Box tuned at 33,3 Hz

[talnlnky]

yep.... funny how a single error on the T/S specs can really throw off your graphs.
Glad you got it figured out.

Seeing as you are playing with ID & focal i'd guess you are a bit on the SQ side of things.
Something that I had good results with when doing modeling was to make a ported box, tune it in the 28-33hz range, and make the box a tiny bit smaller than required to get a flat response. Basically, I tried to get the Ported box to rolloff near the same rate as a sealed box would.

The reason why I liked doing this is beacause...
1: group delay would be low due to the tuning being lower than normal (for car audio)

2: Doesn't give a boomy sound like many poorly tuned ported boxes have.

3: Sounds just like a sealed box setup, except it can play a bit lower, and is a bit more efficient.


The main problem is being able to fit the port in the box, a low tuning, and a small box don't mix.... especially if you have a high excursion woofer that needs a lot of port area.


Also... I noticed the Le (inductance) value on the Focal sub... If you like "tight" and "quick" sounding bass, in the future, look for a sub with a lower Le value... as the Le has to do with how quickly the Voice coil gets saturated by the magnetic flux....(how quick it can change directions). Try to find a sub below 2mH. Some subs even get below 1.


EDIT: Oh yeah... almost forgot... Say "Hi" to Hugo for me. :-)