Geddes on Waveguides - Page 493 - 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 2nd November 2010, 06:01 AM   #4921
R.I.P.
 
Join Date: Jan 2008
Quote:
Originally Posted by gedlee View Post
Seems to me that the opposite is really the case as all of the "experts" seem to be in complete consensus.
Easy for you to say, having recently altered your own view on this, apparently:

Geddes on Waveguides


Quote:
Originally Posted by gedlee View Post
I think that this question has been well researched and the data points in the direction of a slightly falling direct response with a parallel falling power response. This is the way of nature and it only seems logical that it is what we perceive as natural.
Am I the only one to have noticed that Gedlee speakers now let the top octave roll down?

Last edited by ZilchLab; 2nd November 2010 at 06:06 AM.
  Reply With Quote
Old 2nd November 2010, 06:26 AM   #4922
ScottG is offline ScottG  United States
diyAudio Member
 
Join Date: Feb 2003
Location: US
Quote:
Originally Posted by ZilchLab View Post

Am I the only one to have noticed that Gedlee speakers now let the top octave roll down?
He is now referencing them off-axis, and isn't displaying the response on-axis (or at varying degrees). You can still see it in the polar intensity map though. (..again, the color difference/magnitude is deceptive for those interested in exceptional linearity.)
__________________
perspective is everything
  Reply With Quote
Old 2nd November 2010, 12:44 PM   #4923
gedlee is online now gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by ZilchLab View Post
Easy for you to say, having recently altered your own view on this, apparently:

Geddes on Waveguides


Am I the only one to have noticed that Gedlee speakers now let the top octave roll down?
I don't see your point because I have not changed my opinion. The link referes to the "width" of the constant directivity NOT to the need for constant directivity. The later is well studied, as I said, but the former is not. No change in my position.

I used to design for flat response, but then recommend that people taper off the high end because, subjectively, flat was deemed to be "bright". I had done this myself for years and you can see this in many of my comments. Now I just roll-off the high end in the product. It just makes more sense to do it that way. Again, no change in position, just a change in implimentation.
  Reply With Quote
Old 3rd November 2010, 01:43 AM   #4924
R.I.P.
 
Join Date: Jan 2008
They are related. The wider the directivity and the more "constant" it is, the closer it approximates flat power response, which is acknowledged as being "overly bright." The issue is power response and in-room sound power, with a suggestion that some constant directivity designs may broadcast excessive high frequency energy into a small-room listening space, and thus, the frequency response should be tilted down in this region for a more optimum balance. This approach is preferable to controlling the power response with collapsing dispersion, in my view, and for adaption to various room characteristics, should likely be made variable. See Tannoy, et al....
  Reply With Quote
Old 3rd November 2010, 02:36 AM   #4925
diyAudio Member
 
dantheman's Avatar
 
Join Date: May 2008
Location: Mountain View, CA
I really can't imagine the top octave plays all that high of a roll in a subjective eval of a speaker. If it did, this speaker would sound bright as can be:
Click the image to open in full size.

Then look at the average of that graph:
Click the image to open in full size.
Most definitely not a bright sounding speaker.

On the other hand, this:
Click the image to open in full size.
Click the image to open in full size.
I'm sure many would call bright. Obviously, nothing to back this up, but if you've read
http://www.gedlee.com/downloads/AES06Gedlee_ll.pdf
it may be believable.

Dan
__________________
My Blog
My Music Recordings
  Reply With Quote
Old 3rd November 2010, 05:02 AM   #4926
AllenB is offline AllenB  Australia
diyAudio Member
 
Join Date: Oct 2008
I find that my first opposite side reflections need to be absorbed. At first I didn't try this because I assumed the opposite ear would separate the reflections.

My sides at this point are different, one diffracts more and one is more reflective. They are 8ms from the direct. They throw off imaging and the reflective side contains a considerable amount of energy.

It occurs to me that the first opposite reflection path is more on axis that my listening axis is, and this concerns me.
  Reply With Quote
Old 3rd November 2010, 04:35 PM   #4927
diyAudio Member
 
dantheman's Avatar
 
Join Date: May 2008
Location: Mountain View, CA
Allen, when you absorb opposite reflections, you also absorb same side reflections. I wouldn't discount that little tidbit in what you are hearing depending on exactly how you are doing it.

When you say diffracts more do you mean diffuses more?

Do you mean that the reflection is closer to you than the speaker?

Probably the wrong thread to get too deep into room issues, but I found your post a bit confusing.

The stuff I posted is regardless of room conditions. However, the more absorptive the room, the less problems you hear with the speaker in my experience. Dr. Toole agrees.

Dan
__________________
My Blog
My Music Recordings
  Reply With Quote
Old 3rd November 2010, 10:19 PM   #4928
AllenB is offline AllenB  Australia
diyAudio Member
 
Join Date: Oct 2008
Quote:
When you say diffracts more do you mean diffuses more?
Yes

Quote:
Originally Posted by dantheman View Post
Allen, when you absorb opposite reflections, you also absorb same side reflections. I wouldn't discount that little tidbit in what you are hearing depending on exactly how you are doing it.
No. The reflection points for first same side and first opposite side are in different locations (four side absorbers needed in total).

My point is simply this. My first same side reflection comes off the front baffle almost perpendicular to it. My listening axis is at around 20 degrees, and the first opposite side reflection leaves the front baffle at 5 or 10 degrees from it.

Therefore, although the first same side is close in time to the direct, and it is also the same ear, the energy is lower. I find this makes each of these type of reflection just as necessary to deal with as each other, in my case. FWIW, subjectively the first opposite side reflection was less damaging to the sound, in and of its own, but the brute force of the magnitude made it a bigger issue.


By the way, I use ARTA. What is the benefit of using the energy time curve? When I measure I get a time/magnitude plot which I'm then expected to convert to a frequency response, or ETC etc. but I find the plain time/magnitude plot easier for locating the spikes that show the reflections.
  Reply With Quote
Old 4th November 2010, 01:37 AM   #4929
gedlee is online now gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by ZilchLab View Post
The wider the directivity and the more "constant" it is, the closer it approximates flat power response,
That is incorrect, but I suspect that you said it wrong, i.e. its not what you meant. The "width" of te directivity has nothing to do with the "flatness" of the "power response". If the directivity is "constant" then the power response tracks the axial response, but that doesn't imply "flat".
  Reply With Quote
Old 4th November 2010, 03:49 AM   #4930
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Quote:
Originally Posted by AllenB View Post
It occurs to me that the first opposite reflection path is more on axis that my listening axis is, and this concerns me.
Can you give us a little diagram to illustrate this?
  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



New To Site? Need Help?

All times are GMT. The time now is 05:42 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