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

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 February 2020, 04:15 PM   #1061
gedlee is offline gedlee  United States
diyAudio Member
 
gedlee's Avatar
 
Join Date: Dec 2004
Location: Novi, Michigan
Quote:
Originally Posted by mabat View Post
Probably I missed something, but in what way is that different from testing compression drivers then?
I understand that this might be hard to grasp and I may have said it wrong. The more the source deviates from flat the more HOMs there will be. HOMs decrease exponentially below cutoff and it is these evanescent waves that are so difficult to measure. Hence with a dome, one will have lots and lots of HOMs because the dome is not flat. This means that the measurements will be far less representative near the source than they would be for a flatter source. This error would propagate into any calculations of a waveguides effect, more or less depending on the waveguides specific design, rendering the results less than desirable. That's why I say that a measurement of a dome in a tube would be misleading.

Better would be a similar reconstruction technique where the dome is placed on an infinite baffle and its' radiation reconstructed from those measurements. But having tried this, the numerical instabilities are problematic.

Quote:
Originally Posted by mabat View Post
Basically, by moving the crossover frequency lower (by means of a larger horn), the less of phase distortion there will be in the most sensitive hearing range - that's a simple fact.
Quote:
Originally Posted by mabat View Post
As I understand it, any horn is a minimum phase device through the typical crossover region, so when equalized for a flat amplitude response, it would have a flat phase as well - there is no phase distortion from the horn itself. It is the all-pass behaviour of the crossover that distorts the summed time response.
Then wouldn't a larger waveguide end up being the same as a smaller one, if they were both EQ'd to be the same?
__________________
Earl Geddes Gedlee Website
  Reply With Quote
Old 19th February 2020, 04:34 PM   #1062
mabat is offline mabat  Czech Republic
diyAudio Member
 
mabat's Avatar
 
Join Date: Sep 2004
Location: Prague
Now I understand, thank you.

Quote:
Originally Posted by gedlee View Post
Then wouldn't a larger waveguide end up being the same as a smaller one, if they were both EQ'd to be the same?
It would, that's what I meant. The on-axis amplitude and phase responses would be the same. Or not?
__________________
www.at-horns.eu
  Reply With Quote
Old 19th February 2020, 05:34 PM   #1063
BYRTT is offline BYRTT  Denmark
diyAudio Member
 
BYRTT's Avatar
 
Join Date: Dec 2009
Quote:
Originally Posted by chebum View Post
There will be less phase distortion because of lower crossover frequency or because of a larger horn?
To self study how minimum phase looks for a given of a bandpass (its all pass behavour) suggest fire up free Rephase and use tab called "Minimum-Phase Filters", now set a HP and LP filter to form stop bands to kind of simulate acoustic slopes for a transducer and watch how phase turn 90 deg per order out of band and 45 deg in band, set for example some LR filters of a given order and see if you togle them between HP and LP their phase is same, tip do one filter then hit "Generate" button to freeze it as a red graph result and then shift filter be it HP or LP, also one can open Rephase multiple times and hover mouse over them multiple times of icons to simulate different setting of filters and how they compare.
  Reply With Quote
Old 19th February 2020, 06:26 PM   #1064
chebum is offline chebum  Poland
diyAudio Member
 
Join Date: Apr 2018
Location: Warsaw
Quote:
Originally Posted by BYRTT View Post
To self study how minimum phase looks for a given of a bandpass
Thank you for the suggestion. Did you mean that unless horn+driver combination gives flat frequency response, the phase will grow towards the low frequencies?

-horn-jpg
Attached Images
File Type: jpg horn.jpg (98.5 KB, 309 views)
  Reply With Quote
Old 19th February 2020, 07:20 PM   #1065
fluid is online now fluid  Australia
diyAudio Member
 
Join Date: Jan 2009
Quote:
Originally Posted by chebum View Post
Thank you for the suggestion. Did you mean that unless horn+driver combination gives flat frequency response, the phase will grow towards the low frequencies?
As the lower frequencies roll off then the phase will increase.

To check for yourself in the control settings of the spl tab in REW press the generate minimum phase button which will give you a minimum phase version of the measurement and you can see if there is any excess phase there.
  Reply With Quote
Old 19th February 2020, 09:13 PM   #1066
BYRTT is offline BYRTT  Denmark
diyAudio Member
 
BYRTT's Avatar
 
Join Date: Dec 2009
Quote:
Originally Posted by chebum View Post
Thank you for the suggestion. Did you mean that unless horn+driver combination gives flat frequency response, the phase will grow towards the low frequencies?...
We can't hide minimum phase reality as fluid say thanks, phase follow amplitude as it vary up and down and especially exstreme at stopband because amplitude is not there anymore, be it a acoustic or electric case stuff is frequency dependant in high frequency is a shorter lenght in time than relative lower frequency so at a passbands HP corner phase will lag and at LP corner phase will advance. Your REW curve could get flat phase if it was EQed say flat amplitude down to 20Hz but voicecoil and stroke would get out of range, also never expect REW to show textbook phase in upper octave, that is because phase is at zero point at half of the used sampling rate so there is some visual distortion there compared to textbook visual in Rephase. As said maybe try some exercises in Rephase and maybe export as frd or wav and import into REW or use free VituixCAD as below example where you see a simple textbook 20Hz-20kHz system using 1kHz 4th order LR slopes, grey phase includes allpass summing reality and green phase was optimal for sum of system amplitude had one transducer could cover it all, difference between grey and green is also called excess phase.

-c_1-png
Attached Images
File Type: png C_1.png (40.0 KB, 253 views)

Last edited by BYRTT; 19th February 2020 at 09:16 PM.
  Reply With Quote
Old 23rd February 2020, 08:44 AM   #1067
jzagaja is offline jzagaja  Poland
diyAudio Member
 
Join Date: Jun 2004
Location: Szczecin
To me M2 style wavguide has very similar H,V,D directivity plot (60 deg coverage, 50cm length). Possible to draw it more rectangular in ATH 4.4.1?
__________________
Visit us at http://www.diysoundgroup.com
The SEOS™ Project http://www.avsforum.com/t/1291022/he...-rallying-here
  Reply With Quote
Old Yesterday, 07:58 AM   #1068
mabat is offline mabat  Czech Republic
diyAudio Member
 
mabat's Avatar
 
Join Date: Sep 2004
Location: Prague
I would have to check what changed in what release and probably get back to an older code which is something I hesitate to do. I remember I had to reduce the minimum for corner radius to 1 mm but don't know when.

Also the possibility of free-air (roundover) termination was removed in the last release, IIRC. It would be tiresome to modify it all in this old code - I won't do that. I didn't plan to touch it at all but as the writing of the new (redesigned) tool takes longer than I hoped for, at least I implemented the superformula which was easy. This is all I can offer for now.
__________________
www.at-horns.eu
  Reply With Quote
Old Yesterday, 08:02 AM   #1069
mabat is offline mabat  Czech Republic
diyAudio Member
 
mabat's Avatar
 
Join Date: Sep 2004
Location: Prague
In the meantime I progress on the PWT hardware (mic plugs for 6 mm electrets) -
Attached Images
File Type: jpg mic_plugs.jpg (245.5 KB, 79 views)
__________________
www.at-horns.eu

Last edited by mabat; Yesterday at 08:07 AM.
  Reply With Quote
Old Today, 10:22 AM   #1070
mabat is offline mabat  Czech Republic
diyAudio Member
 
mabat's Avatar
 
Join Date: Sep 2004
Location: Prague
gedlee

Re PWT, I'm not sure you mentioned this before - what about a (typical) conical exit of a compression driver connected directly to a straight duct? Wouldn't that deteriorate the results? I will have two tubes, ⌀1" and ⌀1.5" - would a smooth transition insert from 1" to 1.5" make sense for 1" drivers? These could be printed easily, I guess.
__________________
www.at-horns.eu

Last edited by mabat; Today at 10:30 AM.
  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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Easy horn (Eazy Horn) still work? Alternatives? Soldermizer Subwoofers 2 4th March 2014 06:01 PM
For sale: Sound easy V18 & Acoustic-dimension stepped attenuator Tazzz Swap Meet 8 3rd November 2012 09:00 AM
easy exponential horn speakers anyone? 12345chris Full Range 9 21st March 2012 12:32 PM
Easy horn, quadrant horn? Hentai Multi-Way 2 29th January 2012 09:50 AM
An easy to build classic horn? dabbler Multi-Way 22 1st September 2011 09:01 AM


New To Site? Need Help?

All times are GMT. The time now is 10:42 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki