Beyond the Ariel - Page 712 - 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 11th August 2010, 12:30 PM   #7111
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Hello,

Here's some more wavelets on TD15 impulse response posted earlier. This is the "full damping" case. There are three transforms of different wavelet lengths of 1ms, 2ms and 5ms. These are non-normalised so amplitude information is true. Also notice that the frequency axes have different scales.

From 1ms wavelet one can see energy is packed at 2.5ms. But there are things happening before 2ms also.

In 5ms wavelet the direct sound and the energy at 2.5ms are overlapping and comb filtering occurs. These is mostly visible at 2ms and between 2-4kHz.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.


It seems clear to me that the energy at 2.5ms is cabinet reflections/diffractions. Maybe that was obvious already
Attached Images
File Type: png TDfulldamping_multireso_1ms.PNG (59.2 KB, 443 views)
File Type: png TDfulldamping_multireso_2ms.PNG (71.6 KB, 444 views)
File Type: png TDfulldamping_multireso_5ms.PNG (83.9 KB, 446 views)
  Reply With Quote
Old 11th August 2010, 12:38 PM   #7112
soongsc is offline soongsc  Taiwan
diyAudio Member
 
soongsc's Avatar
 
Join Date: Mar 2005
Location: Taiwan
It would be interesting to see the electrical impedance of this test article.
__________________
Hear the real thing!
  Reply With Quote
Old 11th August 2010, 12:39 PM   #7113
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
I don't know what is your position but nothing you have said so far changes the fact that "frequency response" indicates system's response at steady state. This is what I said in the beginning and you opposed.

- Elias


Quote:
Originally Posted by JohnPM View Post
In the limit an infinitesimally short sweep is an impulse, and I think we know the term used for the output of a system when driven by an impulse. Perhaps you are aware that sweeps are also referred to as "time stretched pulses", particularly amongst Japanese researchers, and the motivation for their use is to spread the energy of the impulse out in time so that the total energy delivered is far greater than the system could cope with if an impulse were used directly. Or perhaps not.
  Reply With Quote
Old 11th August 2010, 12:45 PM   #7114
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
One measurement I would like to see is to place the two enclosures back to back and feed the signal only to the front one as before. This would propably remove the diffraction at 2.5ms and place it further in time domain. Just to validate (by direct comparision) that the 2.5ms really is from the cabinet.

- Elias
  Reply With Quote
Old 11th August 2010, 12:57 PM   #7115
diyAudio Member
 
Join Date: Aug 2006
Elias my tests of the AE drivers were on an open baffle, so there was no rear wall reflection.

From John J's comments I take it that this is a suspension or cone issue. It is not as noticeable with the fabric surrounds, although it is still there. It is also most noticeable on the 15" drivers. My guess is it is cone/surround interface issue. Similar to the dip you see around 800-1000hz, on smaller drivers, especially 8" woofers for whatever reason. Or cone flex issue that is mitigated by fabric surrounds but not helped by foam surrounds.

Anyway I haven't seen any big woofers with better IR than the AE drivers so not sure what the fuss is about.
__________________
~Brandon
DriverVault Soma Sonus Old Driver Tests
  Reply With Quote
Old 11th August 2010, 03:58 PM   #7116
g3dahl is offline g3dahl  United States
diyAudio Member
 
g3dahl's Avatar
 
Join Date: Jun 2004
Location: Silverdale, WA
Quote:
Originally Posted by augerpro View Post
Elias my tests of the AE drivers were on an open baffle, so there was no rear wall reflection.
Same here. I tested without the cabinet, and the 2.5 ms wrinkle was still there.

Quote:
Anyway I haven't seen any big woofers with better IR than the AE drivers so not sure what the fuss is about.
My feelings exactly! Judging by the results, I'm pretty sure that Nick McKinney worked hard to chase out every problem he could while developing this driver.

All of the 15" drivers I have used have brought a certain quality (solidity, authority) to the presentation that I really like. As with everything else in speaker design, there are compromises as well. The TD15M doesn't measure as cleanly as the little Vifa drivers in the Ariel, but its strengths are obviously different.

As much as I have liked the other 15" drivers I have used (Altec 416, 515, 604, Klipsch K-48), I don't expect the TD15M will be a disappointment.

Of course I am curious about the cause of the 2.5 ms ripple, but I have less than two weeks remaining before starting back to work, and need to focus on completing the crossovers.

Gary Dahl
__________________
"So many tubes, so little time..."
  Reply With Quote
Old 11th August 2010, 04:04 PM   #7117
Sheldon is offline Sheldon  United States
diyAudio Member
 
Join Date: Dec 2003
Location: San Diego
Quote:
Originally Posted by soongsc View Post
I was under the impression that there was no intension to tweek the driver.
Gary did say he was not interested in modifying the driver. However, if simple reversible damping could be applied to the spider (assuming that's indeed the source of the reflection/resonance), then he or others might try it. But not much point until it's determined that the phenomenon is an audible issue in the given application. I have 15" Lambda TDX (Apollo motor) in my system. Since I cross them around 400Hz, I'm not much motivated to experiment. John at AE might be interested in mitigating this issue, especially since these drivers do have extended frequency response.

Sheldon
  Reply With Quote
Old 11th August 2010, 04:17 PM   #7118
JohnPM is offline JohnPM  United Kingdom
diyAudio Member
 
Join Date: Oct 2008
Quote:
Originally Posted by Elias View Post
I don't know what is your position but nothing you have said so far changes the fact that "frequency response" indicates system's response at steady state. This is what I said in the beginning and you opposed.
Elias, without in any way wishing to appear rude, that is a meaningless statement. The system's frequency response and impulse response are interchangeable, they both describe the same system and how it affects signals that pass through it. Would your statement make sense to you if it read "the impulse response indicates the system's response at steady state"? There seems to be a continual confusion between the system's frequency response, which is an invariant property of the system, and the spectrum of the system's output and/or the spectrum of segments of the system's impulse response as it evolves over time. They are not the same thing.
  Reply With Quote
Old 11th August 2010, 06:22 PM   #7119
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Hi,

EE102: Introduction to Signals & Systems

Chapter 10: "Sinusoidal steady-state and frequency response"
http://www.stanford.edu/~boyd/ee102/freq.pdf


Quote:
Originally Posted by Elias View Post
"frequency response" indicates system's response at steady state.

Quote:
Originally Posted by JohnPM View Post
that is a meaningless statement.
  Reply With Quote
Old 11th August 2010, 07:26 PM   #7120
JohnPM is offline JohnPM  United Kingdom
diyAudio Member
 
Join Date: Oct 2008
Quote:
Originally Posted by Elias View Post
Hi,

EE102: Introduction to Signals & Systems

Chapter 10: "Sinusoidal steady-state and frequency response"
http://www.stanford.edu/~boyd/ee102/freq.pdf
Nice to see where your misunderstanding has come from Elias, but unfortunately you have things back to front. The response to a sinusoid, just like the response to any input, is determined by the frequency response (including the transient behaviour). The frequency response is not determined by hanging around for the transients of applying an infinity of sinusoids to decay.
  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 05:04 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