# Is sub modeling really useful?



## Fricasseekid (Apr 19, 2011)

So I've heard the sub modeling can have huge variance from real world application. I'm NOT talking about in cabin acoustics here. 

I've heard that one can model several subs in a box and the loudest one in the model might be the quietest one in actuality and visa versa. Also heard that along with output that a sub model can lie about group delay and box sizing and anything else I suppose. 

Do these discrepancies exist and if so how could one go about identifying them in order to make box modeling a useful tool?


----------



## trumpet (Nov 14, 2010)

If you want to see some videos that might blow your mind about subwoofer box modeling, including cabin simulation, check out "Hexibase" on YouTube. He has really opened my eyes on some audio topics. ‪Means & Ends (Enclosure Design)‬‏ - YouTube


----------



## ChrisB (Jul 3, 2008)

Unfortunately, sub modeling isn't always an ends to a means because many manufacturers lie about certain T/S parameters or publish specs from "perfect" production samples. The only subs that I measured close to spec with a Woofer Tester 3 were those from JL Audio. A certain other manufacturer is always lying about their FS, but I won't name them because I am nice.


----------



## Fricasseekid (Apr 19, 2011)

ChrisB said:


> Unfortunately, sub modeling isn't always an ends to a means because many manufacturers lie about certain T/S parameters or publish specs from "perfect" production samples. The only subs that I measured close to spec with a Woofer Tester 3 were those from JL Audio. A certain other manufacturer is always lying about their FS, but I won't name them because I am nice.


Is that why I always have to fudge the numbers to get WinISD pro to accept a new sub? Lol


----------



## XtremeRevolution (Dec 3, 2010)

Fricasseekid said:


> So I've heard the sub modeling can have huge variance from real world application. I'm NOT talking about in cabin acoustics here.
> 
> I've heard that one can model several subs in a box and the loudest one in the model might be the quietest one in actuality and visa versa. Also heard that along with output that a sub model can lie about group delay and box sizing and anything else I suppose.
> 
> Do these discrepancies exist and if so how could one go about identifying them in order to make box modeling a useful tool?


Have you heard this, or have you actually experienced or proven it? I haven't yet modeled something that I couldn't prove in a real world environment. You can identify all of those discrepancies by getting the most information you possibly can when modeling your box. Its not an exact science by any means, and the simulations are just that; simulations, but they get us pretty close to what the final response will be. 

The sub box models don't lie; they're either misinformed (inaccurate published T/S parameters), or certain elements are left out, such as a non-defeatable high pass filter, which will actually reduce the total group delay by as much as 20ms. Again, things WinISD may not necessarily model for you, or at least not easily. There are so many things that come into effect that its not even funny. For the record, I never liked WinISD Pro. 



ChrisB said:


> Unfortunately, sub modeling isn't always an ends to a means because many manufacturers lie about certain T/S parameters or publish specs from "perfect" production samples. The only subs that I measured close to spec with a Woofer Tester 3 were those from JL Audio. A certain other manufacturer is always lying about their FS, but I won't name them because I am nice.


You are 100% correct, it isn't a means to an end. Some manufacturers list their T/S specs before the subs are broken in. For sub box modeling I do for people in person, I break in the sub overnight playing a test tone at high excursion, let the voice coil cool, and measure the T/S parameters with my WT3 so I can model from there. It changes the results a bit, but often its not too significant. In fact, I just built a set of mini bookshelf speakers with a 3.5" driver, and the published Fs was 13hz off from the measured broken in Fs. 



Fricasseekid said:


> Is that why I always have to fudge the numbers to get WinISD pro to accept a new sub? Lol


There might be a lot of reasons. All I know, modeling is all we've got. You can either go by what the manufacturer recommends, or you can model it. Last time I checked what Alpine recommended for their new 8" sub, the vent velocity at max power was near 60m/s. That's absolutely insane. In cases like those, I'd rather model the box, and so far, people have come back either in my thread or through private messages telling me that the box sounded exactly what I modeled it to sound like and they absolutely love it. Not one person has come back yet saying they were unpleasantly surprised by the results.


----------



## rexxxlo (Apr 14, 2009)

Try mr kings papers on quarterwave modeling they are written around modeling and measuring and having acurate results to back up the model very closely


----------



## fish (Jun 30, 2007)

ChrisB said:


> A certain other manufacturer is always lying about their FS, but I won't name them because I am nice.



1508?


----------



## ChrisB (Jul 3, 2008)

fish said:


> 1508?


Every single 1508 I owned and my 1010. The last 1508 I measured had a Fs of 59.22 Hz and the 1010 that I gave to my sister measured at 39.03 Hz. According to DD, the 1508 has a Fs of 42.39 Hz and the 1010's is 27 Hz.


----------



## ryan s (Dec 19, 2006)

Fricasseekid said:


> Is that why I always have to fudge the numbers to get WinISD pro to accept a new sub? Lol


For Pro, you need to enter things a certain way, in a certain order, for the program to accept them.

Conversely, you can model things quickly with only Fs, Qts, and Vas entered. The downside is lack of excursion info and the like. But that's the fast way to get a box size.


----------



## Fricasseekid (Apr 19, 2011)

ryan s said:


> For Pro, you need to enter things a certain way, in a certain order, for the program to accept them.
> 
> Conversely, you can model things quickly with only Fs, Qts, and Vas entered. The downside is lack of excursion info and the like. But that's the fast way to get a box size.


Yeah it took me some time, but I finally figured out that it seems to have a sort of priority order. There is definitely a learning curve.


----------



## XtremeRevolution (Dec 3, 2010)

Fricasseekid said:


> Yeah it took me some time, but I finally figured out that it seems to have a sort of priority order. There is definitely a learning curve.


Try the software I'm using by jbagby. Its a bit easier to understand, and everything is modeled on one screen, one page, and its easy to see the effects your changes have.


----------



## Fricasseekid (Apr 19, 2011)

XtremeRevolution said:


> Try the software I'm using by jbagby. Its a bit easier to understand, and everything is modeled on one screen, one page, and its easy to see the effects your changes have.


Already did. The software wouldn't work on my computer for some reason. I haven't had time to try and reload it yet. Besides I got WinISD figured out now.


----------



## XtremeRevolution (Dec 3, 2010)

Fricasseekid said:


> Already did. The software wouldn't work on my computer for some reason. I haven't had time to try and reload it yet. Besides I got WinISD figured out now.


Did you get the macros enabled and working? The spreadsheets are useless if the macros don't work.


----------



## Fricasseekid (Apr 19, 2011)

XtremeRevolution said:


> Did you get the macros enabled and working? The spreadsheets are useless if the macros don't work.


To be honest man I'm not very computer savvy. So I guess not...


----------



## minbari (Mar 3, 2011)

I like WinISD, as said before, it is not the end-all be-all for making a system, but if you dont want to go the trial and error route on box biulding, it works pretty well. you may have to adjust port length a little to tune it just right, but for the most part, it is right on. I have made many boxes based on what it said and have always been happy with the results.


----------



## The Tube Doctor (Nov 24, 2009)

For day-to-day stuff, I still use LFDES. 
The really detailed stuff, and on those occasions when the T/S parameters appear to be
provided by the marketing, rather than the engineering department, I use LEAP/LMS.
If you don't trust the numbers provided, LMS can measure them accurately.
LEAP can model things most of us don't even know exists!
Just remember GIGO................


----------



## Fricasseekid (Apr 19, 2011)

The Tube Doctor said:


> For day-to-day stuff, I still use LFDES.
> The really detailed stuff, and on those occasions when the T/S parameters appear to be
> provided by the marketing, rather than the engineering department, I use LEAP/LMS.
> If you don't trust the numbers provided, LMS can measure them accurately.
> ...


??? Got any links?


----------



## minbari (Mar 3, 2011)

leap is nice, but $800-1500

LinearX Systems Inc - Pricing


----------



## XtremeRevolution (Dec 3, 2010)

Here's something someone said in my thread regarding to a box I modeled for them a few weeks ago. 



NucFusion said:


> I can tell you that the modeled response he made for me based on a box I already had made is almost spot on from what I measured using test tones and a rat shack spl meter. I haven't built the sealed box yet to see if the modeled response would be correct or not. I'm going a bit of a different direction with my box placement, so not sure if I wil build it or not, just to see.


----------



## The Tube Doctor (Nov 24, 2009)

Yes, LEAP/LMS is expensive, but I do product development for some companies, 
I'm in Hong Kong, which is next door to China's primary manufacturing centers,
so the expense is justified.
LEAP/LMS requires proprietary hardware, in addition to its software, so you've 
unlikely to find any useful cracked versions. I've heard of a V4.51 crack, but have not 
found it necessary. 
I've had LFDES in my computers forever, and I don't know what's become of the 
company that published it so long ago. Company's name was SpeakEasy, from Newton, MA.
I know it's a tease, but LFDES is really my go-to program. I especially like the 
CURVE FIT function. Makes me lazy at times......................


----------



## BuickGN (May 29, 2009)

I think the software is great for comparing subs. I modeled the Tempest X IB before installing it and I didn't know what to make of it. Then I did the same with my AE IB15s. Comparing both subs showed exactly what I heard. The Tempest X was a super bottom heavy sub with very little past 40hz and required over twice the power of the IB15. I really didn't know how it would sound based on just one subwoofer but with both graphed out after listening it all made sense. Now I always have the IB15 up when modeling other subs since I'm familiar with their sound.


----------



## Fricasseekid (Apr 19, 2011)

sheirly88 said:


> i like Super slim subwoofer
> 1. slim----can save a lot space Size: 345X240X68mm,
> 2.cable controled--- convenient
> 3good sound quality
> ...


Um, spam alert?!!


----------



## Fricasseekid (Apr 19, 2011)

BuickGN said:


> I think the software is great for comparing subs. I modeled the Tempest X IB before installing it and I didn't know what to make of it. Then I did the same with my AE IB15s. Comparing both subs showed exactly what I heard. The Tempest X was a super bottom heavy sub with very little past 40hz and required over twice the power of the IB15. I really didn't know how it would sound based on just one subwoofer but with both graphed out after listening it all made sense. Now I always have the IB15 up when modeling other subs since I'm familiar with their sound.


This is what I've been doing. My past sub set up had no bottom end and was very boomy due to peaks around 60 hertz. So I compare all my models to that model to get an idea of how it may sound. My next set up is 5 db louder at 60 and 11 db louder at 30 hz. and my last set up was exceeding xmax and my new set up stays under xmax. None if this includes cabin gain but I'd still conclude that the difference will be night and day in SPL and SQ. I hope I'm right. How realistic is that gonna be in a real world situation ?


----------



## XtremeRevolution (Dec 3, 2010)

Fricasseekid said:


> This is what I've been doing. My past sub set up had no bottom end and was very boomy due to peaks around 60 hertz. So I compare all my models to that model to get an idea of how it may sound. My next set up is 5 db louder at 60 and 11 db louder at 30 hz. and my last set up was exceeding xmax and my new set up stays under xmax. None if this includes cabin gain but I'd still conclude that the difference will be night and day in SPL and SQ. I hope I'm right. How realistic is that gonna be in a real world situation ?


Understanding that the human ear perceives a 2x increase in volume every time output is increased by 10db, that's 2x louder at 30hz and 50% louder at 60hz. That's a HUGE difference. What was the Qtc on your old box?


----------



## Fricasseekid (Apr 19, 2011)

XtremeRevolution said:


> Understanding that the human ear perceives a 2x increase in volume every time output is increased by 10db, that's 2x louder at 30hz and 50% louder at 60hz. That's a HUGE difference. What was the Qtc on your old box?


Ok, don't laugh at me. I've built boxes before but this is the first time I've actually learned what I'm doing....

My new box will be right around .801
And the old one was around 1.2, but the woofers are very high Q woofers. 

I'm not sure exactly what that means aside from the shape of the response graph.


----------



## XtremeRevolution (Dec 3, 2010)

Fricasseekid said:


> Ok, don't laugh at me. I've built boxes before but this is the first time I've actually learned what I'm doing....
> 
> My new box will be right around .801
> And the old one was around 1.2, but the woofers are very high Q woofers.
> ...


Not laughing, we all learn, but a Qtc of 1.2 is like, wow terrible, lol. That's like, choke the hell out of the sub small. Even .801 is a bit high, but should sound much better.


----------



## Fricasseekid (Apr 19, 2011)

XtremeRevolution said:


> Not laughing, we all learn, but a Qtc of 1.2 is like, wow terrible, lol. That's like, choke the hell out of the sub small. Even .801 is a bit high, but should sound much better.


Yeah I agree, but I have a whole inch of one way travel so I plan on using 5 dbs of boost at 30 hz and the model show the speakers remaining under xmax with 1000 watts. This actually makes the sealed box model almost identical to a ported of the same volume.


----------



## Fricasseekid (Apr 19, 2011)

cajunner said:


> this is incorrect, when taking frequency into account.
> 
> the lower the frequency, the louder it must be to hear it at the same perceptual level as a higher frequency, in the low range.
> 
> ...


Well I've done all the modeling myself, but i am curious to see what others com up with, so:

- 2 Polk MM 1240 DVC
- 3 ft^3 sealed (net volume)
- 1000 watts RMS
- +5 db increase @ 30 Hz. (with a Q factor of 1)

I came up with about 117 db @ 30 Hz and 122 db @ 60 Hz (not including cabin gain).


----------



## Fricasseekid (Apr 19, 2011)

The last box was 1.7 CF (net) sealed and I was running 2 Powerbass S-12TD, I ran them on everything from 400 watts to 1500 watts (they sounded great on the later for about 1.5 hours)


----------



## The Baron Groog (Mar 15, 2010)

XtremeRevolution said:


> There might be a lot of reasons. All I know, modeling is all we've got. You can either go by what the manufacturer recommends, or you can model it. Last time I checked what Alpine recommended for their new 8" sub, the vent velocity at max power was near 60m/s. That's absolutely insane. In cases like those, I'd rather model the box, and so far, people have come back either in my thread or through private messages telling me that the box sounded exactly what I modeled it to sound like and they absolutely love it. Not one person has come back yet saying they were unpleasantly surprised by the results.


Have you checked Ground Zero's recommended boxes out? Never seen anything so ridiculous in my life.

The GZ Plutonium SPL woofer is rated for 6500watts in SPL comps, box recommended is 1.75cf with 2x 4"ID x 10" long ports=145m/s vent velocity! Even at "only" 1000w it's 57m/s.

Recommended enclosures are on the whole a waste of time, I will always "mess around" and see what's going to play best. 

Big issues today are high Q, low VAS subs-try designing a ported enclosure for them and you end up with a huge enclosure which is 90% port-I really must get better with hornresp as I'm sure some killer tapped horns could be done with them if I had the skills.


----------



## captainscarlett (Mar 15, 2011)

The Baron Groog said:


> I'm sure some killer tapped horns could be done with them if I had the skills.


That'll get the 'Nay-sayers'*started! 

Modelling an enclosure including basic Transfer function numbers is one thing, but I believe to really get the best our of an enclosure, one would have to go a bit further. After speaking to a few sound engineers, each have suggested that i look beyond BBP or WinSD etc.


----------



## minbari (Mar 3, 2011)

There are allot better programs out there, but they cost allot of money too. For free, win isd does a good job

Sent from my Motorola Electrify using Tapatalk 2


----------



## thehatedguy (May 4, 2007)

Learn Hornresp and akabak.

Both are totally free and soooooooo powerful once you learn how to use them.

And the guys who published akabak have other cool free software like axidriver and ABEC. The paid versions differ from the free in that you can not save files in the free version, but all the features remain.

Learn how to use those, and using winISD will only be for really rough guesses.




minbari said:


> There are allot better programs out there, but they cost allot of money too. For free, win isd does a good job
> 
> Sent from my Motorola Electrify using Tapatalk 2


----------



## The Baron Groog (Mar 15, 2010)

HR I'm getting better with, my main issues are the translation of the text into an enclosure-I'm dyslexic and the visual aspect of BBpro really helps with my understanding of what's going on-HR is like that green **** in The Matrix-was it the blue or red pill I need to take?

Akabak I've yet to try, the T-TQWT I desinged (ok got a lot of help with) still needs making-so no immediate need for me to start trying to use that until I finish the 1st project!


----------



## minbari (Mar 3, 2011)

thehatedguy said:


> Learn Hornresp and akabak.
> 
> Both are totally free and soooooooo powerful once you learn how to use them.
> 
> ...


from what I could tell hornresp only works for horn sims. if that is wrong please correct me. I tried to use that and it takes forever to get it setup.

tried akabak, but its MSDOS heritage seems to be dating itself on my systems. none of the "buttons" seem to do anything. I input all the param for a woofer start clicking and nada.



LEAP is the one I was thinking of that costs alot.


----------



## The Baron Groog (Mar 15, 2010)

minbari said:


> from what I could tell hornresp only works for horn sims. if that is wrong please correct me. I tried to use that and it takes forever to get it setup.
> 
> tried akabak, but its MSDOS heritage seems to be dating itself on my systems. none of the "buttons" seem to do anything. I input all the param for a woofer start clicking and nada.
> 
> LEAP is the one I was thinking of that costs alot.


hornresp will model sealed and vented enclosures too - or so I've been told, I've not worked it out yet-Patrick Bateman knows how to.


----------



## thehatedguy (May 4, 2007)

Hornresp for Dum... hmm... Everyone  - Home Theater Forum and Systems - HomeTheaterShack.com


----------



## The Baron Groog (Mar 15, 2010)

thehatedguy said:


> Hornresp for Dum... hmm... Everyone  - Home Theater Forum and Systems - HomeTheaterShack.com


Sweet! best guides I've seen to date


----------

