Square wave test on speakers - what does it tell ? - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

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 23rd April 2014, 03:32 PM   #1
diyAudio Member
 
Join Date: Sep 2009
Location: Stavanger (NORWAY)
Default Square wave test on speakers - what does it tell ?

Hi,
looking for information about speakers testing i have found this table showing an excellent response of the speaker to square wave.

Click the image to open in full size.

I wonder if this kind of test can tell something about the sound quality of a speaker.
Thanks and regards,
gino
  Reply With Quote
Old 23rd April 2014, 04:07 PM   #2
boris81 is offline boris81  United States
diyAudio Member
 
Join Date: Oct 2009
Location: white plains, ny
Only speakers with a Linear Phase can reproduce a square wave.
Conventional IIR crossovers introduce a phase shift that alters the waveform. This distortion is generally considered inaudible. Exotic FIR crossovers, 1st order IIR crossovers and single driver speakers are the common approaches to building a linear phase speaker.
  Reply With Quote
Old 23rd April 2014, 04:37 PM   #3
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
there are higher order linear phase, linear (analog, RLC) filter alignments possible although they "waste" some driver frequency and SPL range by having larger overlap regions

but XO and driver filter response summing flat, linear phase is not a guarantee of good radiated soundfield response given the physical separation and size/directivity differences of multiple drivers - may only happen along a specifically angled axis between the multiple drivers and be increasingly poor away from that axis

there is research - not just anecdote - that midband phase rotation from allpass filters given the same phase/frequency found in some popular high order XO multiway loudspeakers can be heard with test signals, and some music, the ability may need training to develop the sensitivity - most easily controlled, tested with simulated phase shifts while listening with good quality headphones

however the effect of "non linear" phase (frequency variable group delay) in common loudspeaker design doesn't seem to be a major audible defect as long as both channels match

Last edited by jcx; 23rd April 2014 at 04:55 PM.
  Reply With Quote
Old 23rd April 2014, 04:48 PM   #4
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Careful choice of frequencies and microphone positioning will occasionally yield
some good looking square waves with loudspeakers which do not generally have
a such excellent square wave response.

  Reply With Quote
Old 23rd April 2014, 05:25 PM   #5
diyAudio Member
 
Join Date: Mar 2007
Location: California
NP is hinting at the fact the the response will change with position relative to the loudspeaker. This is because in order for the speaker to reproduce a square wave all the different frequency components must arrive at the same time (in phase). But as you move esp. in the vertical plane, the distances to each driver change, and so does the phase. You can sometimes find points in space for which things align nicely but move a foot away and the square wave may no longer be constructed properly.

Even FIR filters that make the phase linear suffer from this phenomenon - that is they really only have this property at one point in space.
  Reply With Quote
Old 23rd April 2014, 05:26 PM   #6
diyAudio Member
 
Join Date: Sep 2009
Location: Stavanger (NORWAY)
Thank you all for the very kind and valuable advice
If i understand rightly what is depicted as a great achievement has no practical consequences on the actual quality of the speaker sound
Now i also understand why this test is so uncommon.
Thanks a lot and kind regards,
gino
  Reply With Quote
Old 23rd April 2014, 05:30 PM   #7
a.wayne is offline a.wayne  United States
Sin Bin
 
Join Date: May 2008
Location: Front Row Center
Nope not entirely , like anything else involving measurements in audio, the real story is not told by just one form of measurement.
  Reply With Quote
Old 23rd April 2014, 06:14 PM   #8
mitchba is offline mitchba  Canada
diyAudio Member
 
Join Date: Jul 2011
Location: Sunshine Coast
Quote:
Originally Posted by ginetto61 View Post
Hi,
looking for information about speakers testing i have found this table showing an excellent response of the speaker to square wave.

I wonder if this kind of test can tell something about the sound quality of a speaker.
Thanks and regards,
gino
Wrt speaker system testing in the time domain, typically the step response of the speaker is what is measured:

Measuring Loudspeakers, Part Two Page 2 | Stereophile.com

Measuring Loudspeakers, Part Two Page 3 | Stereophile.com

The links above show examples of what a "good" step response looks like.

One can use REW, a free measurement tool, to measure and inspect the step response of a speaker system, along with many other measures.

While some may disagree, personally from REW measurements, I have found the "quality" of sound increases from a speaker system that is time coherent as compared to speakers that are not. My experiment involved ripping out a passive 3 way XO, replaced with 3 way digital XO and time aligning the drivers, while measuring the before and after step responses.

As the Stereophile article notes, there are really few speaker systems that measure time coherent, so unless one has listened to a speaker system that measures time coherent, it is hard to compare.

One measure I did want to include is to show that the step response remains relatively the same at 6 different mic locations across a 6' x 2' measurement grid (i.e. couch listening area) of my right speaker some 9ft away:

Click the image to open in full size.
  Reply With Quote
Old 23rd April 2014, 10:04 PM   #9
tvrgeek is offline tvrgeek  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Md
All the fancy DSP in Sound Easy UE may make a square wave look better, but I am not at all convinced it matters any to the actual sound.
  Reply With Quote
Old 23rd April 2014, 11:17 PM   #10
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
It should be noted that Rehdeko speakers use series XOs -- their info shown in post 1.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  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
LTspice square wave and audio amp test maouna Solid State 2 11th December 2010 10:34 AM
How to run a square wave test on an OPT?? Ultima Thule Tubes / Valves 7 28th December 2009 11:47 AM
Sine wave - Square & Triangle wave generator using Transistors / OP-Amps lineup Solid State 20 9th October 2006 01:15 AM


New To Site? Need Help?

All times are GMT. The time now is 08:01 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