Hornresp - Page 257 - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

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 7th February 2012, 02:56 PM   #2561
Jmmlc is offline Jmmlc  France
R.I.P.
 
Join Date: Oct 2005
Hello Mimura,

No it will not affect the simulation, only the graph of the phase is more difficult to read when there is a 180° phase reversal.

Best regards from Paris, France

Jean-Michel Le Cléac'h


Quote:
Originally Posted by mimura View Post
Hello David and all the members.
Thanks for the help. I do not know if it will affect projects that are going to do it. I do not know much about such details.

Thank you for good.
  Reply With Quote
Old 7th February 2012, 03:11 PM   #2562
bjorno is offline bjorno  Sweden
diyAudio Member
 
Join Date: Mar 2005
Location: Jacobsmountain
Send a message via MSN to bjorno
Quote:
Originally Posted by tb46 View Post
Hi David,

I'll attach a screen print of some notes in a spreadsheet. Using these values seems to work well enough. Please, let me know if you find any big mistakes.

Regards,
Hi Oliver,

I found no mistakes..but maybe a very small one(I too do sometimes) unless you forgot to nullify your Fluke (8060A?) when measure the Re of the drivers using the 200 Ohm scale, of course.

b
  Reply With Quote
Old 8th February 2012, 04:52 AM   #2563
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by jamikl View Post
I'm using ADSL2+. If I wait long enough I get the "Web page is not Available"message. I've been trying for three days now - same result each time.
Hi jamikl,

Sorry, but I have no idea why you can no longer access the Hornresp webpage.

Not sure if it will make any difference, but you could try the following alternative address:

Hornresp

Kind regards,

David
__________________
www.hornresp.net
  Reply With Quote
Old 8th February 2012, 05:45 AM   #2564
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by tb46 View Post
I'll attach a screen print of some notes in a spreadsheet. Using these values seems to work well enough. Please, let me know if you find any big mistakes.
Hi Oliver,

Many thanks for the information - I had suspected that you were probably using this method, but I wanted to be sure. It has been documented in a number of places, and is presumably based on the isobaric model originally described by Marshall Leach in his book "Introduction to Electroacoustics and Audio Amplifier Design". Unfortunately, as far as I can see, he got it wrong, and everyone else has just propagated the error :-).

I simply cannot see how fs can stay the same...

fs = 1 / (2 * Pi * (Mms * Cms ) ^ 0.5)

where Mms = Mmd + airload

For an isobaric pair, Cms = Cms / 2 and Mmd = Mmd * 2. For fs to remain the same, the airload mass would also have to double. This does not happen - the airload mass is increased slightly due to the inclusion of the cavity between the two diaphragms, but that is all.

The fs for an isobaric pair will therefore be higher than that for a single driver.

To illustrate, assuming that Cms = 0.0004 metres per newton, Mmd = 0.04 kilogram, front and back airload mass = 0.01 kilogram and isobaric cavity airload mass = 0.001 kilogram, then:

Single driver fs = 1 / ( 2 * Pi * ((0.04 + 0.01) * 0.0004) ^ 0.5) = 35.59 hertz

Isobaric pair fs = 1 / ( 2 * Pi * ((0.08 + 0.01 + 0.001 ) * 0.0002) ^ 0.5) = 37.31 hertz

The fs shift can be readily see in AkAbak using the complete isobaric model - see attached comparison.

Because fs changes, so too will Qes and Qms.

If anyone can see a flaw in my reasoning, could they please let me know.

Using the technique I described earlier for Hornresp should lead to more accurate predictions than those obtained with your current method. To make things easier for users, I will probably now add an isobaric configuration option to the Driver Arrangement tool, as you have suggested :-).

Kind regards,

David
Attached Images
File Type: png Compare.png (33.1 KB, 122 views)
__________________
www.hornresp.net
  Reply With Quote
Old 8th February 2012, 05:48 AM   #2565
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by bjorno View Post
A starting point reference is single coil DVC TS parameters that can be found here:
Thanks bjorno. Please see my post above.

Kind regards,

David
__________________
www.hornresp.net
  Reply With Quote
Old 8th February 2012, 10:14 AM   #2566
jamikl is offline jamikl  Australia
diyAudio Member
 
Join Date: May 2005
Location: Melbourne
Thanks David, the alternative address worked fine.
jamikl
  Reply With Quote
Old 8th February 2012, 02:03 PM   #2567
tb46 is offline tb46  United States
diyAudio Member
 
Join Date: Jan 2006
Location: Texas
Default Post #2564

Hi David,

Thanks so much for your effort of looking into this. At least I seem to be in good company with my mistaken assumptions. I hope to be able to-again-get to some practical measurements in the near future, and I will definitely let you know how they come out. Meanwhile, I'm looking forward to the isobaric feature in Hornresp. :-)

Regards,
__________________
Oliver
  Reply With Quote
Old 8th February 2012, 02:29 PM   #2568
Mark Kravchenko --- www.kravchenko-audio.com
diyAudio Member
 
mwmkravchenko's Avatar
 
Join Date: Jan 2002
Location: Perth Canada
Quote:
Using the technique I described earlier for Hornresp should lead to more accurate predictions than those obtained with your current method. To make things easier for users, I will probably now add an isobaric configuration option to the Driver Arrangement tool, as you have suggested :-).
Whoo Hoooo!

Can you throw in a multiple vent calculator while you are at it Sensei McBean?

I have all but given up in using WinISD. And I will very shortly present the findings I have been working on vent velocity predictions versus simulations from Hornresp. One last round of verification this evening.

IMG_20120204_163316(1).jpg

Oh I have to put this up. I just did a back loaded horn design that performs very admirably. And exactly as predicted. Thanks David. Without your work mine becomes so much harder. You are very much appreciated.
__________________
Mark
  Reply With Quote
Old 8th February 2012, 04:15 PM   #2569
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by David McBean View Post
For an isobaric pair, Cms = Cms / 2 and Mmd = Mmd * 2. For fs to remain the same, the airload mass would also have to double. This does not happen - the airload mass is increased slightly due to the inclusion of the cavity between the two diaphragms, but that is all.

The fs for an isobaric pair will therefore be higher than that for a single driver.

Because fs changes, so too will Qes and Qms.

If anyone can see a flaw in my reasoning, could they please let me know.
David,

I don’t see a flaw in your reasoning that the isobaric pair Fs would increase slightly.

Made me recall the opposite happening with "normal" parallel speakers.

The TS parameters on the specification sheet for the Electrovoice EVX-150 15 inch woofer state a single driver having 35 FS, .251 QTS.
The spec sheet also says “Multiple driver application: When used in arrays and multiple bass boxes, the system Theile-Small parameters can be synthesized as follows:
For two drivers the FS drops to 34, QTS .260, and for four, FS is 32.5, QTS .270.

Do the formulas used for multiple speakers in Hornresp also predict a lower FS and a rising QTS?

Art
  Reply With Quote
Old 8th February 2012, 09:41 PM   #2570
neets is offline neets  Denmark
diyAudio Member
 
Join Date: Mar 2011
where can I buy the mentioned programme "Hornresp 18.20"?
  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
Hornresp Class FlipC Subwoofers 8 3rd November 2008 06:23 PM
Some questions about hornresp brsanko Full Range 4 18th October 2008 09:36 PM
Hornresp help / JX150 316a Multi-Way 0 11th February 2004 03:56 PM


New To Site? Need Help?

All times are GMT. The time now is 02:20 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