1.5th order filter phase shift ? - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

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
Thread Tools Search this Thread
Old 15th August 2013, 02:29 AM   #1
diyAudio Member
Join Date: Jul 2010
Default 1.5th order filter phase shift ?

Hi, I've got a question about crossover design.

If the 2nd order crossover has the 180 degree phase shift (+90 degree from hi-pass and -90 degree from low-pass, the sum is 180 degree phase shift) so, the tweeter in 2nd order crossover must be wired 'reverse' polarity.

But If I have only hi-pass filter (without lo-pass filter) which I'll call it 1.5th order. Should the tweeter still be wired 'reverse' polarity ?

Thank you.
  Reply With Quote
Old 15th August 2013, 02:31 AM   #2
diyAudio Member
Join Date: Jul 2010
Or Should it be wired one reverse and the other don't ?
  Reply With Quote
Old 15th August 2013, 04:18 AM   #3
DavidL is offline DavidL  United States
Join Date: Jul 2010
You are correct in your first post but ONLY if you also ignore the drivers acoustic roll offs and the horizontal spacing between drivers. Your analogy only applies to "text book" crossovers and not the real world. Each driver has it's own natural rolloff anywhere between 6 to 18 dB per octave then you have the horizontal acoustic difference which may add another 90 to 180 degrees or anything in between depending upon the crossover frequency. All must be taken into account and the actual crossover adjusted which isn't possible just by guessing at it.

Please read the Sticky at the top of this forum Introduction to designing crossovers without measurement

Last edited by DavidL; 15th August 2013 at 04:22 AM.
  Reply With Quote
Old 15th August 2013, 05:39 AM   #4
expert in tautology
diyAudio Member
bear's Avatar
Join Date: Apr 2002
Location: New York State USA
Noticed ur post...

Your question revolves around two areas.
First what is happening in the area where the drivers outputs overlap, commonly known as the crossover region.
Second is what is happening to the overall summation of the drivers output WRT the original inputted signal. For example, music, or better still, an impulse. The impulse is often used in FFT measurement systems, and to look at "impulse response".

Within reason, in my view it is more important to get the HF section and the LF section to sum when looking at the impulse than to get a perfectly flat response in the xover region.

Serendipity and physics tend to team up to make the absolutely best impulse response also result in very good results in the xover region, but one can get one without the other...

Btw, I think your analysis of the amount of phase shift between the pass band and the stop band of the 2nd order filter is not quite right, although it is possible that i am confused on that subject too.

There is no 1.5th order filter in standard analog designs...afaik.

http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- every once in a while I say something that makes sense... ]
  Reply With Quote
Old 15th August 2013, 05:46 AM   #5
BHTX is offline BHTX  United States
diyAudio Member
BHTX's Avatar
Join Date: Feb 2006
Originally Posted by presscot View Post
But If I have only hi-pass filter (without lo-pass filter) which I'll call it 1.5th order. Should the tweeter still be wired 'reverse' polarity ?
I would think it would depend mainly on the natural roll off characteristics of the woofer (I'm assuming you're talking about not using a low pass filter on the woofer). Also, physical spacing between sound sources should also be considered, as pointed out by DavidL. From what little I know, you'd normally only use a woofer without a low pass filter if its inherent roll-off is in a desired location and is smooth enough to do so, and that's pretty rare these days. One of the only good examples that comes to my mind at the moment is the 10" Seas A26RE4, intended to be a modern version of the woofer used in the old Dynaco A25. I'm sure there are some others out there, poly cones and whatnot with smoother roll offs. As for 1.5th order phase shift, I'm not sure where you're getting that from.

Last edited by BHTX; 15th August 2013 at 05:49 AM.
  Reply With Quote
Old 15th August 2013, 06:26 AM   #6
system7 is offline system7  United Kingdom
diyAudio Member
system7's Avatar
Join Date: Aug 2008
Location: Portsmouth UK
I wouldn't attempt to guess phase without doing a sim of the whole setup, since the bass and treble drivers will usually have acoustic centres offset by a few centimeters.

Learn to sim a speaker:

Visaton provide plenty of kit examples and sample Boxsim files which you can import too:
HiFi-/Surround Kits
Boxsim Projektdatenbank 2 Wege
Best Regards from Steve in Portsmouth, UK.
  Reply With Quote


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
phase shift of second order filter bondo Multi-Way 9 8th April 2009 02:24 AM
Crossover order and phase shift NV&H Multi-Way 1 28th December 2008 08:31 AM
Zero phase-shift gareth Solid State 11 9th May 2008 04:45 PM
5th order filter chip Russ White Chip Amps 8 9th June 2005 04:19 PM
DSP LPF with zero phase-shift, & filter design software. Circlotron Digital Source 5 5th August 2002 06:18 PM

New To Site? Need Help?

All times are GMT. The time now is 11:00 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2