What is a "phase lens"? - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

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
Reply
 
Thread Tools Search this Thread
Old 19th January 2008, 01:34 AM   #1
diyAudio Member
 
Join Date: Nov 2007
Default What is a "phase lens"?

http://www.partsexpress.com/pe/showd...Number=264-512

Out of curiosity, what exactly is a "Phase lens/shield" and what is it's purpose?
  Reply With Quote
Old 19th January 2008, 10:31 AM   #2
diyAudio Member
 
Join Date: Nov 2007
I think it cancels out or at least shift the direction to the sides , the ultra sonic breakup mode of the tweeter.

I've removed a phase lens from a tweeter before, and it sounds better without it. Namely the tweeter in my B&W CDM1 SE.
  Reply With Quote
Old 19th January 2008, 03:31 PM   #3
DcibeL is offline DcibeL  Canada
diyAudio Member
 
DcibeL's Avatar
 
Join Date: May 2003
Location: Saskatchewan
I think in the case of the driver you linked to, it's marketing buzz. They have come up with a fancy name for a speaker guard.

Now, if you are talking about phase plugs, then that's a different story.
__________________
The power of Science compels you!
  Reply With Quote
Old 19th January 2008, 05:45 PM   #4
Ron E is offline Ron E  United States
diyAudio Member
 
Ron E's Avatar
 
Join Date: Jun 2002
Location: USA, MN
It blocks radiation from the very tip, which otherwise would combine destructively with the radiation from the edge and cause a high frequency droop.

It also serves admirably to protect the rather thin domes on these tweeters as well. I dented my D25 and then removed the dome and gently massaged out the dent so it is no longer visible, the response is still different from the undamaged tweeter.
__________________
Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works. --Carl Sagan
Armaments, universal debt, and planned obsolescence--those are the three pillars of Western prosperity. Aldous Huxley
  Reply With Quote
Old 19th January 2008, 06:03 PM   #5
diyAudio Member
 
Join Date: Nov 2007
Thanks for the help!

I was thinking about whether or not to remove the phase thingy from my tweeter, and was curious as to how it changes the sound. Any advice?

Here is the tweeter I have:
http://www.partsexpress.com/pe/pshow...number=275-055

Probably should've linked to it in the first post...getting lazy I guess
  Reply With Quote
Old 19th January 2008, 06:49 PM   #6
diyAudio Member
 
Richard Ellis's Avatar
 
Join Date: Sep 2006
Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
Default Phase lens

JBL had their 'lens' on the front of the very popular component series of horns from years ago ...some had quite a complex/pretty design, the theory was a particular point source of sound had to travel furthur toward the edges so it traveled a longer path and was so called aligned with a wave that traveled inline with the horn.
JBL called them lenses...attached to the face of their horns.
_____________________________________Rick......... .....
Attached Images
File Type: jpg lens.jpg (27.2 KB, 176 views)
  Reply With Quote
Old 20th January 2008, 12:36 AM   #7
jdlech is offline jdlech  United States
diyAudio Member
 
Join Date: Dec 2007
Quote:
Hard-domed tweeters, in most cases, include what is called a "phase shield". This is usually in the form of a disc-shaped piece of material supported, in one way or another, directly in front of the dome and centered on it. It's not been used in hard-domed midrange drivers at all, to my knowledge.

There is at times some misunderstanding of just what this shield does. It doesn't alter phase per se, as it cannot alter the phase of the signal as it emerges from the dome. Its purpose is to block the output from the tip of the tweeter, the reason being that at the upper range of tweeters, somewhere around 10KHz and up, the signal emanating from the tip will actually arrive at the listener prior to that sound emanating from the rim, where the former attaches to the diaphragm. At high frequencies the time difference is significant enough that there is a phase delta that causes interference to occur.

The reason that this occurs is because a hard-domed diaphragm is pistonic to a much higher frequency than softer diaphragms. Essentially, the speed of sound is much faster in the hard material than it is in air, it therefore reachs the tip and emanates form it before the sound passing through the air originating from the diaphragm rim area can reach the equivalent distance out from the driver.
Taken from http://www.speakerdesign.net/dayton_...yton_rs52.html

Judging from that information, removing it should cause interferance. It might make sense to remove it if you are using a higher order crossover - to counter it's phase shift (ever so slightly, I imagine). But that's something I would not try unless I could measure phase/frq and distortion before and after.

I'm just guessing.
  Reply With Quote
Old 20th January 2008, 12:43 AM   #8
diyAudio Member
 
Join Date: Nov 2007
guess I'll leave it on then. I mean if it serves a purpose, might as well let it do it's job
  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
JVC "EXU-901a" (KRELL KPS-25sc Phase Tech CT-1 CT1) better than VAM1254, CDpro2LF ? tiefbassuebertr Digital Source 14 12th January 2012 08:12 AM
Looking for phase plug ideas for horn loaded 10" and 12" drivers Eva Multi-Way 10 11th December 2011 05:17 PM
Hi Res 550mm Fresnel Lens Set, 15"x11" First Surface Mirror, 6.3" IR/UV Filter, More! Ben_Tech Swap Meet 0 22nd September 2007 10:49 PM
Helper tweeter lens via ~Karlson idea "THE KUP" freddi Full Range 0 25th November 2006 06:54 PM


New To Site? Need Help?

All times are GMT. The time now is 08:37 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