6th order bandpass subwoofer - Page 3 - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th January 2003, 08:42 AM   #21
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
nice one.
One thing, you'd need a box that is 183 litters in total for that band pass, and ur comparing it to a 81 litter vented, try making a 183 litter vented... results would be similar i'd guess... trying it right now
__________________
Time is the best teacher; unfortunately, it kills all its students
  Reply With Quote
Old 19th January 2003, 08:55 AM   #22
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
yep... similar but the bandpass has still a lower f3, nice one.
now thats around 6.5 cuft.. (ouch)

and bandpass is from 54hz to 16hz +\- 3dB

I'd maybe need somehow a bit higher..

check this for a 83hz to 19 hz band pass

front chamber
0.706cutf fb 50hz

rear chamber
3cutf fb 17 hz


vs vented 6.5cuft @ 22 hz

the bandpass is as good as the vented but half its volume. now thats a deal!

what do you guys think of that one?
__________________
Time is the best teacher; unfortunately, it kills all its students
  Reply With Quote
Old 20th January 2003, 01:35 AM   #23
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
that thing i stated above, i tried it today with 3 different apps,

winisd pro
winisd
and jbl speakershop

they all give me some strange results..

winisd pro tells me that a bandpass setup would suck compared to vented box..

winisd shows that a bandpass system would be a better size/performace ratio than vented

and jbl shows some very strange stuff....

any ideas wich one should i trust?
__________________
Time is the best teacher; unfortunately, it kills all its students
  Reply With Quote
Old 20th January 2003, 02:27 AM   #24
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Basically, I wouldn't trust any of them, because of the wierdness of your parameters.

I tried modeling this woofer back in the first thread you started. I used Bullock and White's freeware DOSBOX which, while a DOS program, still accurately computed such things as SPL from the parameters. DOSBOX came up with an SPL, all right, but had to change your Mms parameter to do it.

Then, of course, we tried using the parameters to calculate SPL ourselves. The woofer, by the manufacturer's own stated parameters, is .24% efficient instead of the manufacturer's stated .4% efficiency.

On the same chart where the manfacturer tells us the woofer is .4% efficient, the manufacturer lists other parameters that gurantee the speaker CANNOT be .4% efficient.

Apparently, a woofer with this particular combination of parameters cannot exist in the real world, and that is what is driving these programs nuts.

Here is the model using Subwoofer Simulator. This is running at 50 watts. I had to make a BL product rating, (unstated in the chart), to make this a smooth curve.
  Reply With Quote
Old 20th January 2003, 03:00 AM   #25
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Okay, here is the vented system of 6.5 cu ft and the bandpass system of 3.7 cu ft compared in Subwoofer Simulator, a great freeware program by our own member F4ier.

Subwoofer simulator can be downloaded here:
http://www.geocities.com/f4ier/speaker.htm

The shape looks a little different, but if you check the markings, you see the variation is not any greater than the other programs'.

I included cone excursion for the two systems. Both for frequency response and cone excursion, vented is in white, bandpass is in yellow.

This system is run at 30 watts.

A few observations. First, it is quite useless to build any system that goes down to 20 Hz with this system when your cone excursion is only 4 mm. As you see here, the cone excursion required even at 30 watts is twice your stated cone excursion. And 102 dB is not really hearable at 20 or 25 Hz-you want more than that to be worth your while. Now you know why Shivas and other fine subs have linear excursions over 12 mm.

Does your various programs have a place to fill in the Bl product? The Bl product is unlisted in the chart-but if you put it in, (assuming your program lets you do that) at a value of 13 Tm, I'll bet you will see a curve that is reasonably smotth. The smaller the Tm, the more irregular the response.

Your simulation shows something remarkable that I will explain later. Meanwhile, try inputting that 13 TM value in your various programs and see what happens.

The program where the enclosure worked well probably input a value of 13 Tm automatically, since it is not a spec Max speakers gives us.
  Reply With Quote
Old 20th January 2003, 03:02 AM   #26
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
LOL, after all that it would be helpful if I remembered to include the chart!!
Attached Images
File Type: gif maxpentiventbandpassvented subsim.gif (18.0 KB, 180 views)
  Reply With Quote
Old 20th January 2003, 04:22 AM   #27
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
hum.. seeing those excursion needs, i'd probably want to get something... more excursionable

what about car subs? like the jensens, preety cheap.. specs aint bad at all....

as the tempests and shivas are actualy made for in car usage... even if tey own in home use.
__________________
Time is the best teacher; unfortunately, it kills all its students
  Reply With Quote
Old 20th January 2003, 04:45 AM   #28
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Quote:
Originally posted by Ilianh
hum.. seeing those excursion needs, i'd probably want to get something... more excursionable
Excursionable! LOL, I like it!

It should be pointed out that speakers come with extra excursion outside the linear range. Mechanical excursion-the actual range a speaker can move before damage occurs-is usually at least 1.5 to 2 times the linear excursion, (also written as Xmax). Unless Xmax specifies mechanical, it generally is assumed to mean linear.

That is why I chose 7 or 8 mm for the chart illustration instead of 4 mm. Your speaker can move past the linear ecursion, but compression and distortion begin to set in at that point.

Besides, the lower you go into the deep bass, the higher the SPL ahs to be to have an effect. 102 dB at 20 Hz might not be all that audible to a lot of people.

The configuration might be useful if the room has a mode that enhances bass between 20 Hz and 30 Hz-there it would be good.
  Reply With Quote
Old 20th January 2003, 01:18 PM   #29
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
Quote:
102 dB at 20 Hz might not be all that audible to a lot of people.
hehe, at that frequency and lower ones, on those spls, you dont hear it, you actualy`"feel" it
__________________
Time is the best teacher; unfortunately, it kills all its students
  Reply With Quote
Old 20th January 2003, 01:54 PM   #30
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
That's what they say-you feel it. However, I tried 25 Hz and lower at those dB levels and I didn't feel that much. Maybe it is an individual thing.

You said that you were starting college today. Is this your first day of college, or just the first day of your new semester?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
6th Order Bandpass Subwoofer (rear & front chamber size?) nickthevoice Subwoofers 12 8th February 2008 10:01 PM
WinISD pro to simulate 6th order bandpass subwoofer christophorus Subwoofers 14 13th September 2006 12:58 PM
4th order bandpass 4 way the phantom Multi-Way 3 27th July 2005 06:28 AM
the isobarik 6th order bandpass transmission line folded horn subwoofer idea Yoda Subwoofers 3 24th October 2001 03:00 PM
6th-order Bandpass BAM Subwoofers 1 24th September 2001 05:51 PM


New To Site? Need Help?

All times are GMT. The time now is 09:40 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2