Need some help designing a low pass filter. - 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 26th July 2010, 07:29 PM   #1
Boscoe is offline Boscoe  United Kingdom
diyAudio Member
 
Join Date: Feb 2010
Location: England
Default Need some help designing a low pass filter.

Basically I'm desgining a low budget sub. I am going to use THIS driver and assuming that if it has two coils could I out left and right through it? I don't quite understand that tbh! Anyway I need an active low pass filter for the sub for sub 150Hz into 8ohm for this driver. Can someone give me a hand?

Thanks
Boscoe
  Reply With Quote
Old 27th July 2010, 05:00 AM   #2
cbj591 is offline cbj591  United States
diyAudio Member
 
cbj591's Avatar
 
Join Date: May 2010
Good morning -

By looking at the sub, it is a dual voice coil driver. Each voice coil is 8 ohms. You may use one for 8 ohms, or both in series for 16 ohm, or both in parallel for 4 ohms.

An active crossover is an electronic crossover that is inline with the signal before amplification. The speakers parameters do not have anything to do with the design of the crossover.

Design link - Sub-Woofer Controller

A passive crossover is a crossover that filters a full range signal (using chokes and capacitors) from the amplifier and limits the frequencies going to the driver. See the following link for design calculators. 1 - 4th order = 6db, 12db, 18db, and 24db roll off.

Just enter the frequency (150hz) and ohm rating that you will be running the speaker at and it will calculate the correct values for you. Since you will not be using the high pass part of the calculator, just enter the same ohm value and click calculate.

Just disregard the high pass info and use the lowpass.

ERSE - Crossover Calculator - First Order 2 Way
ERSE - Crossover Calculator - Second Order 2 Way
ERSE - Crossover Calculator - Third Order 2 Way
ERSE - Crossover Calculator - Fourth Order 2 Way

Good luck
Brian
  Reply With Quote
Old 27th July 2010, 07:52 AM   #3
Boscoe is offline Boscoe  United Kingdom
diyAudio Member
 
Join Date: Feb 2010
Location: England
Thanks a lot, so can I put two different channels into each voice coil? If not how can I combine the two channels in the sub without making everything else mono?
  Reply With Quote
Old 27th July 2010, 08:37 AM   #4
diyAudio Member
 
Join Date: Dec 2009
Location: The Hague
when you put a right and a left signal in the diferen vc's and the signal is is stereo (diferent per chanel) you will rip the woofer apart.

Greets Rik
  Reply With Quote
Old 27th July 2010, 09:10 AM   #5
Boscoe is offline Boscoe  United Kingdom
diyAudio Member
 
Join Date: Feb 2010
Location: England
Okay then how do I combine the left and right channels for it?
  Reply With Quote
Old 27th July 2010, 09:18 AM   #6
diyAudio Member
 
Join Date: Dec 2009
Location: The Hague
as Brian stated you van drive them with a mono amp series 16 ohm or 4 ohm paralel, you can also combine the stereo signal into a mono signal with a active lp filter and than feeding the left and right chanel with the same signal.
you'll need to make sure the signal is the same.
its better using a mono amp
  Reply With Quote
Old 27th July 2010, 09:30 AM   #7
diyAudio Member
 
Join Date: Dec 2009
Location: The Hague
or do you already have an amp you’re going to use for the project, if you are what kind of amp? some amps you can use as mono amp in btm (bridge tight mode)

Last edited by rikvancoolwijk; 27th July 2010 at 09:31 AM. Reason: typo
  Reply With Quote
Old 27th July 2010, 09:34 AM   #8
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by Boscoe View Post
Thanks a lot, so can I put two different channels into each voice coil? If not how can I combine the two channels in the sub without making everything else mono?
use a sumer (adder) circuit. An opamp wired for inverting mode ADDs the two inputs to give one output.

Repeat the input resistor for as many inputs that you want to ADD/SUM

If you use an MFB filter as your low pass then it uses the same inverting topology and you can combine the summing function with the filter function in one opamp. You get a 2pole active rolloff and sumer.

Be wary of using Left and Right into a dual VC driver. If the signals are not in phase the VC cooling will be reduced and you could burn out the driver.
__________________
regards Andrew T.
  Reply With Quote
Old 27th July 2010, 11:49 AM   #9
cbj591 is offline cbj591  United States
diyAudio Member
 
cbj591's Avatar
 
Join Date: May 2010
You can hook up the left side to one voice coil and the right side to the other. That was the initial intent behind the dual voice coil speaker design.

You just need to make sure that the voice coils are hooked together in phase.


Brian
  Reply With Quote
Old 27th July 2010, 12:50 PM   #10
Boscoe is offline Boscoe  United Kingdom
diyAudio Member
 
Join Date: Feb 2010
Location: England
So you can do it. That makes things a lot easier and things in phase is just making the wires are the right way round as I am using the same amps and filters on each channel.
  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
designing simple low pass subwoofer filter asbn369 Subwoofers 8 2nd August 2010 12:55 PM
Low Pass filter for sub? cathode_ray Subwoofers 9 25th April 2007 05:04 PM
low pass filter AudioAddicted Car Audio 17 2nd November 2006 06:44 AM
NO low pass filter? jmar Digital Source 7 19th January 2006 12:53 PM
low pass filter crazyant Car Audio 3 15th September 2005 06:15 PM


New To Site? Need Help?

All times are GMT. The time now is 04:32 PM.


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