4th order Subwoofer - 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 24th October 2002, 04:48 AM   #1
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
Default 4th order Subwoofer

I designed this subwoofer, its using 2 8" drivers,
and i wanted to know if the response curves are ok, and if i should do something to make it better, or if its ok
  Reply With Quote
Old 24th October 2002, 04:51 AM   #2
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
heres the pic
Attached Images
File Type: jpg bandpassbox2.jpg (89.1 KB, 470 views)
  Reply With Quote
Old 26th October 2002, 12:37 AM   #3
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
What is the rated SPL @ 1W/1M of your speakers?

The curve of your subwoofer--3 dB at 25 Hz, using two 8 inch speakers, (equivalent of one 12 inch), is very, very good, if the SPL of the rated speakers is 88 dB @ 1W/1M or above. If it is much under that, then there is a dropoff in performance.
  Reply With Quote
Old 26th October 2002, 06:59 AM   #4
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
Thanks for the reply

how can i find the rated SPL @ 1W/1m? i bought those driver preety oem, and thats why they were cheap but i think they are awsome, and i calculated the specs needed for the box design.

I've being working on it, to reduce the volume because it was too big
thats the new version.
what do u think of it?
btw, its all in imperial system
Attached Images
File Type: jpg bandpassboxsmall2.jpg (89.9 KB, 395 views)
  Reply With Quote
Old 26th October 2002, 07:03 AM   #5
Ilianh is offline Ilianh  Canada
diyAudio Member
 
Ilianh's Avatar
 
Join Date: Oct 2002
Location: Montreal, Canada
Send a message via MSN to Ilianh
actualy, this program has something to make advanced calculations and heres what i get.
Attached Images
File Type: jpg woofer 8inch specs.jpg (37.6 KB, 379 views)
  Reply With Quote
Old 26th October 2002, 01:57 PM   #6
BAM is offline BAM
diyAudio Member
 
Join Date: Sep 2001
Location: Carmel, IN; West Lafayette, IN
Send a message via AIM to BAM
Default Drivers are OK

So its sensitivity is 88.03dB as shown by that chart. Now just make sure you use at least a 3" flared port to aviod port noises from trying to pass too much air. Flared ports can move air faster, so a 3" non-flared port might make chuffing sounds, but a 3" flared port probably won't.
  Reply With Quote
Old 26th October 2002, 04:05 PM   #7
diyAudio Member
 
Lligior's Avatar
 
Join Date: Oct 2002
Location: US - Kentucky
your software looks like a newer version of one I have...
I also had the problem with the imperial unit thing. Converting N/mm to Lb/in or whater it is is crazy even with my old TI-85. Try clicking on the Lb/in, it should cycle through and eventually get to N/mm. After you go throughabout 6 different conversions. This also works for all the measurements.
  Reply With Quote
Old 26th October 2002, 07:32 PM   #8
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
A) Your amplitude response at 2.83 input is only about 79 dB. Very very low.

B) The sensitivity of the speakers is given as 88 dB-about normal. However, these are actually 5 or 6 ohm speakers-that sensitivity rating might be inflated.

Sensitivity is sometimes measured by watt, often by 2.83 volts at 1 Meter. 2.83 volts produces one watt in 8 ohm speaker. However, it produces 2 watts in a 4 ohm speaker. A 6 ohm speaker measured this way will be overrated by 1.5 dB-which isn't so outrageous, actually.

Hang on, let me check with this parameter calculator. I thinkyou can do better than that design.
  Reply With Quote
Old 26th October 2002, 08:02 PM   #9
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
I think a best shot is your ported box. If you take a look at the midpoint of your bandpass, you see that it's throughout most of it's range, it's playing at 75 dB or so at 2.83 input.

The sensitivity of the woofers is either 88 or 86.5 dB. The bandpass is lowering their output-smoother line, but lowering the output throughout it's playing range.

The following graph WinISD graph contains two speaker responses.

The one in red is for a bandpass enclosure with characteristics very similar, though not identical, to yours.

The line in blue represents the two woofers in a bass reflex cabinet, 2.6 cu. ft., tuned to 25 Hz.

As you can see, the two curves meet around 25 Hz. However, the ported system is much more sensitive throughout most of the playing range.
Attached Images
File Type: gif custom-bandpass&ported.gif (5.4 KB, 318 views)
  Reply With Quote
Old 26th October 2002, 08:12 PM   #10
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Two more things to consider.

When put near a corner, the output of the port frequency is increased up to 6 dB. It gets less the farther from the corner you go. The ported box's port frequency is 25 Hz-right where you can use a boost. The bandpass box's port frequency is 55 Hz or so-where you don't need help.

In a ported box, the cone is moving ony about one fourth as much as it would in a closed box to produce the same bass. There is probably very little help from the port at 25 or 30 Hz in your bandpass. that means that your cone is moving three or four times as much to produce the same bass output.

When a big bass note comes at 25 Hz or so, you are very likely to run out of excursion with the bandpass. Not with the ported. the port aids the reflex box right where it needs it the most.

Try a reflex box, 2.6 cubic feet, 25 Hz tuning, and see what you get. Oh, yes, the bass distortion will be much less with the reflex box as well.

Just a suggestion.
  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 11:01 PM
WinISD pro to simulate 6th order bandpass subwoofer christophorus Subwoofers 14 13th September 2006 01:58 PM
6th order bandpass subwoofer Ilianh Subwoofers 50 25th January 2003 02:40 AM
An on-line store in Australia / New Zealand to order subwoofer drivers and amps? Dave Bullet Subwoofers 5 13th January 2002 07:12 AM
the isobarik 6th order bandpass transmission line folded horn subwoofer idea Yoda Subwoofers 3 24th October 2001 04:00 PM


New To Site? Need Help?

All times are GMT. The time now is 06:33 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