Sound pressure in time domain - diyAudio
Go Back   Home > Forums > Loudspeakers > Full Range

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 24th March 2006, 02:30 AM   #1
jamikl is offline jamikl  Australia
diyAudio Member
 
Join Date: May 2005
Location: Melbourne
Default Sound pressure in time domain

Could anyone help with an explanation on this as shown in the mathcad simulations. I favour blh enclosures but as mentioned by MJK in one of his papers the double burst shown in this graph has made me wonder a bit. Also, would there not be a similar pattern shown in a bipole MLTL and what effect would this have at a normal listening distance.
Thanks for any help, Mike.
jamikl
  Reply With Quote
Old 24th March 2006, 04:37 AM   #2
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
If the back wave has to travel through the horn first before meeting with the front, it will be out of phase by then. The old sound that was playing momentarily before is now meeting with the current sound from the front.

The time delay is somewhat constant for all frequencies as its main cause is the fixed length horn. This, however, is a different portion of a wavelength for different frequencies.

Where the difference is a small portion of a wavelength, there will be no real problems. Where the difference is half/one and a half etc, there will be nulls. Where there are several wavelengths in it (at higher frequencies) there will be an echo like effect in theory.

If you consider the frequency where the difference will cause your first null, you may be rolling off your blh by then anyway.

Still, I like mine. At the end of the day, it sounds great, even with deep complex organ music with natural reverberation on the recording.

If I remember rightly, Nelson Pass may have mentioned the horn delay was not as bad as it seems on paper.

IMHO, don't try to stop the effect by stuffing your horn. Well, maybe a little, but it really kills it. I prefer to roll off the bass using my electronics if necessary.
  Reply With Quote
Old 24th March 2006, 11:21 AM   #3
jamikl is offline jamikl  Australia
diyAudio Member
 
Join Date: May 2005
Location: Melbourne
Thanks for the reply Indm. I understand what happens with the BLH but am still wondering if the same thing happens with a bipole when moved out 2 - 3 feet from the wall. I did appreciate the BLHs I had years ago and am now tossing up between a Bipole MLTL and the horn. Particularly looking at the Solo with perhaps a mid range using a 3.5" to 4.5" full range speaker in a homebuilt horn as discussed with Colin in an earlier post. General opinion is NOT to mount a front loaded mid and upper horn on a driver that is BLH mounted for bass. I'm open to opinions on this though!
Mike
jamikl
  Reply With Quote
Old 25th March 2006, 08:55 AM   #4
jamikl is offline jamikl  Australia
diyAudio Member
 
Join Date: May 2005
Location: Melbourne
Does any member of the forum have expeience of building with a mid-hi horn on front of a speaker and a BLH for the bass?
Mike
jamikl
  Reply With Quote
Old 25th March 2006, 10:39 AM   #5
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
http://home.vicnet.net.au/~macinc/alf1.htm
  Reply With Quote
Old 26th March 2006, 01:15 AM   #6
jamikl is offline jamikl  Australia
diyAudio Member
 
Join Date: May 2005
Location: Melbourne
Thanks for the reply Indm. I had forgotten about that horn! What you have shown on the link looks great. How low does it go in room?
jamikl
  Reply With Quote
Old 26th March 2006, 02:11 AM   #7
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
I don't know, but probably all the way if done right.

I use my corners. The horn design goes back into the corner and turns inside out over itself and uses the room walls as the mouth. I have to EQ to quieten 20Hz and I'm only using a 7" driver.
  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
Which design to have in-a-car-like sound pressure? Doug Kim Multi-Way 39 29th July 2008 11:49 AM
Store real time sound reading in a memory Progg70 Digital Source 1 29th December 2007 08:48 AM
Signals from musical instruments in time domain PMA Everything Else 41 27th November 2007 09:31 AM
Sound pressure, is that the same? destroyer X Solid State 17 9th May 2004 11:51 PM


New To Site? Need Help?

All times are GMT. The time now is 04:55 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