Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

Best way to balance speaker for a flat response
Best way to balance speaker for a flat response
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 14th August 2019, 08:07 PM   #61
Dave Bullet is offline Dave Bullet  New Zealand
diyAudio Member
 
Join Date: Jan 2002
Location: Wellington, New Zealand
Quote:
Originally Posted by bentoronto View Post
Fine. Let's take your step 1:

"1. model the "perfect" acoustic slope for a particular driver"

I don't know what the slope might be for any driver derived from theory or in practice until tested. Do you or perhaps wintermute knows how to decide?

But I do know that you I would run each driver and see how it outputs, distorts, resonates, takes power, etc. And then using your mature judgment, decide where you need to cut if off and with what slope and in relation to the other drivers. For example, if you like soft dome tweeters you need canny judgment (not perfect theory) about how low you can go.

Seems to me, that exactly zero of this empirical procedure could be in any way described as "'perfect' acoustic slope".

... and that's why you might as well start right off with step 2 even if it violates the Infinitely True Rules of Science as understood by wintermute, and skip 3 and 4.

B.
Perfect in my application would be the ideal acoustic target to hit the crossover point and slope to integrate with other drivers with a passband chosen to optimise dispersion and minimise non-linear behaviour. that's why I put perfect in speech marks. Sorry I thought that was obvious.
__________________
"Usual diyaudio train wreck of dubious drivers and just the crossover to sort out. Well, how are you on crossovers and modelling? Pretty green, I reckon" - system7 (Steve)
  Reply With Quote
Old 14th August 2019, 08:14 PM   #62
mark100 is offline mark100  United States
diyAudio Member
 
Join Date: Dec 2010
Ben, I don't think your square wave example holds water, for a number of reasons.
I agree that square waves are a good way to see phase, but honestly, they aren't much better than a good phase trace from REW...
And lots of folks are getting good phase traces nowadays.

When I use a real scope, square waves stay pretty consistent looking when moving the mic around small amounts like you did.

But neither of my full range e'stats (Acoustat X and CLS) make square waves that look all that good. Both crap out long before 500Hz.
Are you certain yours are as good at it as you think?

Neither of my stats have any form of processing on them...which has a great deal to do with proper phase delivery. Maybe I should try to tune them...

Because good square waves at 1000Hz can be done, as shown below.
And to say good phase info can't reach our ears just because there are reflections etc, simply doesn't make sense imo.

First screen shot below is Acoustat at 490Hz. Just showing it's already crapped out by then.
Next two are a DIY 3-way using a coax CD, at 640 and 1k.
Attached Images
File Type: jpg acoustat 490 sq.JPG (98.7 KB, 186 views)
File Type: jpg diy60 640hz sq.JPG (103.7 KB, 185 views)
File Type: jpg diy60 1K sq.JPG (102.4 KB, 183 views)
  Reply With Quote
Old 14th August 2019, 08:38 PM   #63
Dave Bullet is offline Dave Bullet  New Zealand
diyAudio Member
 
Join Date: Jan 2002
Location: Wellington, New Zealand
Quote:
Originally Posted by bentoronto View Post
But I do know that you I would run each driver and see how it outputs, distorts, resonates, takes power, etc. And then using your mature judgment, decide where you need to cut if off and with what slope and in relation to the other drivers. For example, if you like soft dome tweeters you need canny judgment (not perfect theory) about how low you can go.
Absolutely. A good example is the same soft dome in a 2 or 3 way speaker. I would cross this over differently; shift up the crossover point or steepen the slope in a 3 way for the tweeter for 2 reasons:
1. The midrange is likely smaller than a 2 way so dispersion is improved
2. The tweeter could become the excursion moreso than thermal weak link as larger woofers invariably need less sweep and /or are more sensitive to handle more power
__________________
"Usual diyaudio train wreck of dubious drivers and just the crossover to sort out. Well, how are you on crossovers and modelling? Pretty green, I reckon" - system7 (Steve)
  Reply With Quote
Old 14th August 2019, 08:47 PM   #64
PLB is offline PLB  United Kingdom
diyAudio Member
 
Join Date: Sep 2008
Location: The backbone of England
Ben re. your post number 57.

Read my post again Ben, it asks for impulse response, frequency response and phase response. You have not give any of these, you appear to completely sidestep my questions by just putting up a smoke screen of responses showing a single tone (rich in odd order harmonics) that does not convey any phase data. and two amplitude responses in the time domain.
Neither picture shows an axis labelled phase in degrees. I'm not about to spend time trying to extract data from nothing. None of what you have provided in the way of data correlates with the questions I've asked.
Please don't take the opportunity to reply just to enjoy getting inebriated by the sound of your own verbosity, it just clutters up the thread and doesn't help the TS.

Peter

Last edited by PLB; 14th August 2019 at 08:54 PM.
  Reply With Quote
Old 14th August 2019, 09:14 PM   #65
bentoronto is offline bentoronto  Canada
diyAudio Member
 
Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
Best way to balance speaker for a flat response
Quote:
Originally Posted by mark100 View Post
Ben, I don't think your square wave example holds water, for a number of reasons.
I agree that square waves are a good way to see phase, but honestly, they aren't much better than a good phase trace from REW...
And lots of folks are getting good phase traces nowadays.

When I use a real scope, square waves stay pretty consistent looking when moving the mic around small amounts like you did.

But neither of my full range e'stats (Acoustat X and CLS) make square waves that look all that good. Both crap out long before 500Hz.
Are you certain yours are as good at it as you think?

Neither of my stats have any form of processing on them...which has a great deal to do with proper phase delivery. Maybe I should try to tune them...

Because good square waves at 1000Hz can be done, as shown below.
And to say good phase info can't reach our ears just because there are reflections etc, simply doesn't make sense imo.

First screen shot below is Acoustat at 490Hz. Just showing it's already crapped out by then.
Next two are a DIY 3-way using a coax CD, at 640 and 1k.
Nice square waves (although you seem to have something ringing at 2400Hz). Quads make great ones too. I sometimes get square square waves if I want to take the time to find the right spot. But as we all know, the sound is the same. Which itself, of course, further demonstrates that phase is not a crucial cue.

The question I was addressing was Peter's: do the phases go out of whack if you move your mic a small distance. And if they do scramble, even on axis, what does that say about the heart-felt if evidence-shy yearning on this forum for phase coherence.

I don't see anything in your otherwise meaningful post that criticizes my demonstration of scrambling.

B.
__________________
HiFi aspirations since 1957. "When the toilet paper of experience is depleted, the **** of reason goes unwiped"

Last edited by bentoronto; 14th August 2019 at 09:18 PM.
  Reply With Quote
Old 14th August 2019, 11:22 PM   #66
wintermute is offline wintermute  Australia
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Best way to balance speaker for a flat response
Ben, the point you always seem to miss is that there are things you can do to optimize the speaker *before* taking into account room interactions, which will greatly reduce the number of negative effects you will get from those interactions.

Just correcting in room for things that could have been avoided in the first place if engineered properly, is not my idea of proper speaker design.

IMO it is always better to treat the cause rather than the symptoms.

Tony.
__________________
Any intelligence I may appear to have is purely artificial!
Photography (another hobby)
  Reply With Quote
Old 15th August 2019, 12:25 AM   #67
gedlee is offline gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by PLB View Post
Ben re. your post number 57.

Read my post again Ben, it asks for impulse response, frequency response and phase response. You have not give any of these, you appear to completely sidestep my questions by just putting up a smoke screen of responses showing a single tone (rich in odd order harmonics) that does not convey any phase data. and two amplitude responses in the time domain.
Neither picture shows an axis labelled phase in degrees. I'm not about to spend time trying to extract data from nothing. None of what you have provided in the way of data correlates with the questions I've asked.
Please don't take the opportunity to reply just to enjoy getting inebriated by the sound of your own verbosity, it just clutters up the thread and doesn't help the TS.

Peter
I concur completely.

Your example was dead on.
__________________
Earl Geddes Gedlee Website
  Reply With Quote
Old 15th August 2019, 01:30 AM   #68
bentoronto is offline bentoronto  Canada
diyAudio Member
 
Join Date: Jan 2008
Location: Toronto and Delray Beach, FL
Best way to balance speaker for a flat response
Quote:
Originally Posted by PLB View Post
Ben re. your post number 57.

Read my post again Ben, it asks for impulse response, frequency response and phase response. You have not give any of these, you appear to completely sidestep my questions by just putting up a smoke screen of responses showing a single tone (rich in odd order harmonics) that does not convey any phase data. and two amplitude responses in the time domain.
Neither picture shows an axis labelled phase in degrees.
Quit nit-picking.

My two images show EXACTLY what you requested and they demonstrate phase scrambling clear as day, whether every harmonic is precisely labeled or not.

Scrambling is scrambling and can't be unscrambled. Phase coherence is a minor issue for hearing and psychoacoustics even if it is of any significance to any physics textbook.

Anybody have one of those "test records" with an announcer speaking with reversed polarity to one speaker? Anybody run any of their drivers with reversed polarity for a a couple of days before noticing it? Or might be doing it now? Anybody spent an afternoon trying to figure out which polarity they prefer for their sub-woofer?

B.
__________________
HiFi aspirations since 1957. "When the toilet paper of experience is depleted, the **** of reason goes unwiped"
  Reply With Quote
Old 15th August 2019, 02:11 AM   #69
Dave Bullet is offline Dave Bullet  New Zealand
diyAudio Member
 
Join Date: Jan 2002
Location: Wellington, New Zealand
Quote:
Originally Posted by bentoronto View Post
Anybody spent an afternoon trying to figure out which polarity they prefer for their sub-woofer?

B.
Not an entire afternoon - but long enough to know which setting complimented the woofers in the overlap region. I only have the one sub.

Are you saying relative phase between drivers - no matter what the value (between 0 and 180 degrees) is meaningless and does not affect the sound?
__________________
"Usual diyaudio train wreck of dubious drivers and just the crossover to sort out. Well, how are you on crossovers and modelling? Pretty green, I reckon" - system7 (Steve)
  Reply With Quote
Old 15th August 2019, 01:57 PM   #70
gedlee is offline gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by bentoronto View Post
Phase coherence is a minor issue for hearing and psychoacoustics even if it is of any significance to any physics textbook.
I am not sure what is meant by "phase coherence", but here is my take on phase:

- Absolute phase is irrelevant
- phase linearity with frequency can be an important aspect of perception, but it is not a dominate one, as is frequency response.
- phase linearity, i.e. phase(f) means that there is no variable group delay in the signal (only a uniform time delay across frequency is possible if the phase is linear,) i.e. all components of a transient are time aligned. If this is "phase coherence" then you are incorrect that it is unimportant. If "phase coherence" means something different to you then you must define it.
- Large changes in phase with frequency as measured by the impulse response mean that various portions of a signal arrive at different times, regardless of the phase aberrations caused in steady state signals by reflections etc.
- the ear hears only the transient parts of a signal at higher frequencies, the window length becoming shorter as the frequency goes up such that we hear steady state signals at LFs, but only the transient part at HFs.
- Hence the phase as measured by a windowed impulse response is audible, albeit, not a dominant effect.
__________________
Earl Geddes Gedlee Website
  Reply With Quote

Reply


Best way to balance speaker for a flat responseHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
speaker drivers: flat frequency response does NOT mean good sound quality kinsei Multi-Way 149 19th February 2019 05:53 AM
Flat frequency response speaker has been developed charlie2 Multi-Way 18 12th January 2018 07:16 PM
Why the emphasis on flat speaker response? jmikes Multi-Way 46 8th August 2017 02:31 AM
Flat Impedance and Flat Power response design. system7 Multi-Way 10 11th January 2017 11:57 AM
Flat FR, Flat Power Response, in-phase crossover? RockLeeEV Multi-Way 15 7th February 2012 08:07 PM


New To Site? Need Help?

All times are GMT. The time now is 06:23 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki