Help with 4th Order bandpass enclosure for a 15" 600W dual voice coil subwoofer (PA)

[col]

Help with 4th Order bandpass enclosure for a 15" 600W dual voice coil subwoofer (PA)

Hi, wondering if anyone can help with this:

I have this spare 15" 600W dual voice coil subwoofer (PA) that I want to try in a 4th order bandpass enclosure.

I had 3 of them in powered BR boxes that I got with faults, I was able to repair 2 of them, one of them was broken beyond repair though. I currently have the driver running passive in it's original BR box with the amp bit cut off.

What I would like to do is make a new 4th order bandpass cab so that I don't have to use it with electronic crossovers. A bit of EQ'ing will be fine.

I have run it through WinISD but it doesn't automatically pick a suitable bandpass enclosure and stuffing around doesn't seem to rectify it.

I have WT3 measured specs.

http://pix.minirig.org.au/main.php?...2_GALLERYSID=00de3db6d82d3f5254c7b7a1d9e5b407


Here are some pics:

WT3

http://pix.minirig.org.au/main.php?g2_view=core.DownloadItem&g2_itemId=3492&g2_serialNumber=1

photo from the back:

http://pix.minirig.org.au/main.php?g2_view=core.DownloadItem&g2_itemId=3488&g2_serialNumber=2

WT3 impedance:

http://pix.minirig.org.au/main.php?g2_view=core.DownloadItem&g2_itemId=3497&g2_serialNumber=2

WinISD estimated original BR enclosure:

http://pix.minirig.org.au/main.php?g2_view=core.DownloadItem&g2_itemId=3500&g2_serialNumber=2

Any help would be much appreciated.

cheers,
col.

 

[col]

Looking at WinISD it might be better to go for a 6th Order Bandpass? More difficult to build though I guess.

http://pix.minirig.org.au/main.php?g2_view=core.DownloadItem&g2_itemId=3504&g2_serialNumber=1

http://pix.minirig.org.au/main.php?g2_view=core.DownloadItem&g2_itemId=3507&g2_serialNumber=1

col.

 

[Zero D]

WPR

Hi, I don't see a screenie for the 4th WinISD design, only BR + 6th ?

The 6th looks fine anyway

I havn't heard of those drivers before, do you have a link to their www ?

If you upload the WinISD .WPR file to somewhere like Free File Hosting Made Simple - MediaFire for eg. i will import it & see what i can do.

Regards

 

[djk]

Qts is too low for a BP4.

 

[col]

Hi ZeroD,

I don't think the driver is available on it's own. It's an OEM that came as part of the powered sub package. I have uploaded the WinISD project file here:

http://pix.minirig.org.au/main.php?...2_GALLERYSID=00de3db6d82d3f5254c7b7a1d9e5b407

cheers,
col.

 

[col]

Qts is too low for a BP4.

Hi Djk, yeah I guess thats why WinISD didn't automatically come up with a box for it. The 6th order seems to work though. Iv'e heard that WinISD isn't particularly good at working out 6th order BP cabs though?

col.

 

[Zero D]

6th

Hi, a few points i noticed.

BL = 43.75 NA Seems very high, but if correct i'm impressed !

No Xmax ? Did you omit it, or can't you get it ?

I inputted 4mm just to see, & i expect it should be at least that !

No Pe ? Did you omit it, or can't you get it ?

I inputted 200W just to see, but i "expect" it may take more ! And it appears to be back vented

See my screenie for my design with a 6th. Not massively different, but maybe more what you're looking for ?

Regards

 

[col]

Hi, a few points i noticed.

BL = 43.75 NA Seems very high, but if correct i'm impressed !

No Xmax ? Did you omit it, or can't you get it ?

I inputted 4mm just to see, & i expect it should be at least that !

No Pe ? Did you omit it, or can't you get it ?

I inputted 200W just to see, but i "expect" it may take more ! And it appears to be back vented

See my screenie for my design with a 6th. Not massively different, but maybe more what you're looking for ?

Regards

yeah that looks good. I have added some more parametres to the WPR and uploaded a updated version:

http://pix.minirig.org.au/main.php?...2_GALLERYSID=a27649786e430f46cb14dc9af4bfaf87

The new version has pe and all the basket dimensions. I couldn't get xmax but by pushing on the basket I would say atleast 5mm. When I measured the driver using WT3 I wired the 2 voice coils together (series) and then in WinISD treated it as if it only had one voice coil. I'm assuming that is correct.

cheers,
col.

 

[Zero D]

yeah that looks good.

Thanks

I have added some more parametres to the WPR and uploaded a updated version:

It seems to be identical to me ?

The new version has pe and all the basket dimensions.

They would be in the WinISD .WDR file which you didn't upload.

I couldn't get xmax but by pushing on the basket I would say at least 5mm.

Not far off my estimate of 4mm.

When I measured the driver using WT3 I wired the 2 voice coils together (series) and then in WinISD treated it as if it only had one voice coil. I'm assuming that is correct.

You can wire them in Series, or Parallel.

Compared to a single VC driver SPL @ 1W, Parallel = + 3dB, Series = - 3dB

Series Voice Coils

Revc, BL and Levc = Double of one voice coil.

That's why we see BL = 43.75

Parallel Voice Coils

Revc, and Levc = Half of one voice coil. BL remains the same.

 

[col]

Hi Djk, yeah I guess thats why WinISD didn't automatically come up with a box for it. The 6th order seems to work though. Iv'e heard that WinISD isn't particularly good at working out 6th order BP cabs though?

col.

I found this 6th order bandpass project where the author is using WinISD but not getting accurate results:

http://www.subwoofer-builder.com/bandpass/]

hmmm....

 

[djk]

"Compared to a single VC driver SPL @ 1W, Parallel = + 3dB, Series = - 3dB"

Should read:

"Compared to a single VC driver SPL @ 2.83V, Parallel = + 3dB, Series = - 3dB"

 

[Zero D]

Where's col ?

@ djk

Well i presumed that people would realise that

 

[col]

Where's col ?

@ djk

Well i presumed that people would realise that

I'm here!

Iv'e deleted the old wpr files and uploaded the new one here:

http://pix.minirig.org.au/main.php?...2_GALLERYSID=00de3db6d82d3f5254c7b7a1d9e5b407

cheers,
col.

 

[djk]

"Well i presumed that people would realise that "

I sometimes forget that many beginners read DIYaudio, so I try and be more complete. I still assume too much of the readers from time to time.

 

[Zero D]

Originally Posted by col

I'm here!

So you are

I've deleted the old wpr files and uploaded the new one here:

Got it I notice that you havn't updated the .WDR Driver file to include Xmax & Pe ? Anyway i inputted the same data as previously, & also estimated 2mH for Le.

+-1 1/2dB 41Hz - 102Hz looks fine on screen Please be aware though that BP6 are very intolerant of TSP/Box/Port errors. If you are able to test the driver & get accurate TSP's, so much the better. If they differ by more than a few % then a redesign would be wise.

If you are unable to do that, but already have the wood, or can get it cheaply, then building it anyway would be an interesting exercise i think.

I recommend that you use an Active Xover @ around 80Hz.

Regards

Originally Posted by djk

I sometimes forget that many beginners read DIYaudio, so I try and be more complete. I still assume too much of the readers from time to time.

Understood Regards

 

[col]

nice one, cheers for your help Zero D.

Iv'e got a stack of wood. A friend gave me 4 x 18mm thick 2440x1220mm form ply sheets. That stuff with the black coating they use to pour concrete with.

I will take the driver out of the BR cab and measure it again soon. Going to use it in the car for a bit.

cheers,
col.

 

[Zero D]

@ col

Free driver & free wood, i expect you might already have the glue & screws too You can't beat free

Keep us posted

 

[col]

just a quick update. I built the box, it's working and has a nice tone to it. I haven't done any measurements yet. will try to get the mic on it next week.

There's some more pics here:

Motivity 15" powered Subwoofer AS900

col.

 

[col]

Not as flat in the pass band as I was expecting, but it sounds quite nice. Better than the original BR enclosure:

 

[OscarS]

you can still work with it if you can find the actual tuning frequencies and then play around with the ports and volumes. Looks like they're too close to each other, hence the peakiness centered in the middle.