winISD and BassBox 6 dont agree

Worlick

Member
2014-05-03 4:04 am
Hello,
I have a couple Massive Audio RW12 STG2 subs I'm committed to turning into two end table down firing subs for Home Theatre use. BTW I'm a newbie.... The drivers are dual 4Ohm, so I will end up running a separate pro amp from the sub out feed from the HT box. For aesthetic purposes, I feel my outer dimensions need to stay about 20" high, 18" wide and 24" deep. This would allow for about 4" legs. after bracing etc this allows for just over 4 ft3 or 115 ltrs.

I have attempted to model vented boxes (1 4" X 8" vent) as they seem to go lower, around 26 Hz while the sealed boxes were maybe 32Hz. I'd love to find a way to get them to 20 :(

I put the same info in WinISD Pro alpa, and BassBox Pro 6 and the graphs are very different... WinIsd seems pretty flat where BB has a considerable bump before rolling off.

So a few questions from the smart guys here...

Which graph is more trusted?

Does it really matter?

Would it be better to go sealed anyways?

Any comments you can offer up on design considerations would be greatly appreciated...

Thanks in advance,
Wayne
 

Attachments

  • IMG_3990.JPG
    IMG_3990.JPG
    656.1 KB · Views: 211
Last edited:

just a guy

Member
2006-05-12 6:59 pm
I did a quick sim with the parameters in your picture and it doesn't look like either the WinISD or the BB sims that you did (but it's closer to the WinISD).

I'm not going to bother sharing the results until/unless you tell me where these t/s parameters came from. This manual says the RW 12 Vas is 30.72 liters which is a far cry from the 190 you used, and xmax is twice as much in the manual, as well as all other parameters being different.
MASSIVE AUDIO RW10 USER MANUAL Pdf Download.

Granted, the manual doesn't say Stage 2, but where did you get these specs?

Regardless, it's easy enough to get your desired 20 hz tuning, just make the port longer. And make sure it's wide enough to keep velocity low at xmax.
 

Ron E

Member
2002-06-27 10:41 pm
USA, MN
The title of this thread should be: "Teach me how to use a simulator"
The first question should be: "what am I doing wrong"

Going from the parameters you entered, there seems to be something fishy with the bassbox sim, the plot looks more like a woofer with a Qts of ~1. Check your inputs.
 
The title of this thread should be: "Teach me how to use a simulator"
The first question should be: "what am I doing wrong"

Going from the parameters you entered, there seems to be something fishy with the bassbox sim, the plot looks more like a woofer with a Qts of ~1. Check your inputs.

Yeah, the BB sim does look like it's got a very weak motor but the t/s he entered were all the same as the WinISD inputs. I'm not familiar with BB at all, maybe he added some extra series Re or something?

Anyway, still waiting on a confirmation that these t/s parameters in the pic are actually valid. The manual I linked to says something very different.
 

Worlick

Member
2014-05-03 4:04 am
In the BB pro, the driver is in their database. I tried to transfer them over to a "new driver" in winISD. I just updated the BB Pro app and it is much happier now, the curve is as flat as could be. Ya I am not exactly sure how to use the software, but with the update I just walked through the steps and it appears to be much better. Yikes I am new but not that new? I see the numbers in the winISD are way off? ack! It did calculate a bunch of them... I did use the same document as the link "just a guy" displayed as well

Perhaps for starters, I should check my work closer before reaching out....
 

Attachments

  • IMG_0331.jpg
    IMG_0331.jpg
    754.5 KB · Views: 179

Worlick

Member
2014-05-03 4:04 am
Driver Properties supplied from the BB6 Pro database, (do not match the manual Just a guy pointed out.) There are a few variances I know from wiring the dual coils in series or parallel. BB6 allows for that a s a selection when setting up a project with that driver. I selected series as I will wire in series for 8 ohm resistance.

Name: RW 12
Type: Standard one-way driver
Company: Massive Audio, Inc.
Comment: Reference series
No. of Drivers = 1
Dual voice coils = series
Fs = 23.09 Hz
Qms = 11.71
Vas = 190 liters
Cms = 0.501 mm/N
Mms = 94.8 g
Rms = 1.174 kg/s
Xmax = 8.7 mm
Xmech = 13.06 mm
P-Dia = 256.5 mm
Sd = 519.5 sq.cm
P-Vd = 0.45 liters
Qes = 0.38
Re = 6.92 ohms
Z = 8 ohms
BL = 15.83 Tm
Pe = 200 watts
Qts = 0.37
no = 0.593 %
1-W SPL = 89.88 dB
2.83-V SPL = 90.51 dB
 

Attachments

  • IMG_0332.jpg
    IMG_0332.jpg
    392.6 KB · Views: 169
In the BB pro, the driver is in their database. I tried to transfer them over to a "new driver" in winISD. I just updated the BB Pro app and it is much happier now, the curve is as flat as could be. Ya I am not exactly sure how to use the software, but with the update I just walked through the steps and it appears to be much better. Yikes I am new but not that new? I see the numbers in the winISD are way off? ack! It did calculate a bunch of them... I did use the same document as the link "just a guy" displayed as well

Perhaps for starters, I should check my work closer before reaching out....

This screenshot shows the same parameters that you used last time.

The document I linked to lists VAS at 30.72 liters.

Compare that to the 190 liters you used and that's not even the same driver. That's a difference of a few hundred percent. This has nothing at all to do with parallel vs series wiring. And all the other specs are different too.

Garbage in = garbage out. You need to know the actual specs of the driver you are using if you have any hope of getting a useful prediction from a simulator.
 

Worlick

Member
2014-05-03 4:04 am
Agreed, that is straight from the BB 6 database..... clearly wrong. Seems like using the parameters from the manufacturer are the best bet.... I will tweak the numbers and start over.... I totally get the crap in crap out theory....

Not all of the small number ... names match. I will fill in the ones that are available for sure....

yikes..
and thanks Wayne
 

Worlick

Member
2014-05-03 4:04 am
Since the direct load from the BB6 database does not match what seems to be the manufacturers released data... Ive created a new driver based on the linked document... BB6 seemed to be unhappy at first, had to calculate some of the numbers....
Came up with this one... the red is based on my preferred internal size just at 4 cubic feet after internals while the yellow is their optimum box over 6 cubes.... the green is the vented box with the Active 12 dB/oct. HP Filter
all have that bump just before roll off. But the vented box with the filter seems to go lower Hz.

Better? reasonable? graph
 

Attachments

  • IMG_3994.JPG
    IMG_3994.JPG
    895.1 KB · Views: 103
My whole point was you need to know FOR SURE what the t/s parameters are.

Your drivers (as stated in post 1) are stage 2. The manual I linked to says nothing about stage 2. So that manual is probably not for the stage 2 drivers. BUT it's unlikely that the stage 2 drivers would be THAT different than the regular RW series.

But the point is that you don't know. I wouldn't build anything without measuring the t/s parameters. Maybe if I had a box lying around I would throw them in there and just experiment but that's about all I would do without having known good t/s.

Can't you contact the manufacturer? Can't you measure the t/s?

Anyway, the bump in your simulated response doesn't look great. Again, the red curve looks like a very weak motor driver and the other curves just look weird.
 

Worlick

Member
2014-05-03 4:04 am
All great points... If you look in the doc you linked to, in the right margin/side it has stage 2 in a logo type font. I think they are.. I will look around the Internet and try to confirm the parameters. I do not have the knowledge to measure them myself. There is always the box volumes set by the manufacturer in those same documents... Sealed boxed at around 1.75 ft3. Just don't seem like that's going to create low enough freq for movies..
Thx for the input, really.
Wayne
 

TBTL

Member
2013-10-08 12:26 pm
It is easy to check whether the Vas is closer to 31 or 190 L. Push the cone down and feel whether the suspension is stiff or not. If the Vas is 31 L, the cone will go down about 1 mm for each kg of force you apply. If Vas is 190L, 1 kg of force will move the cone 5 mm.