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

2-way Unity Horn from 300Hz (some noob questions)
2-way Unity Horn from 300Hz (some noob questions)
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 2nd November 2017, 08:07 PM   #11
bwaslo is offline bwaslo  United States
Old guy with soldering iron
diyAudio Member
 
bwaslo's Avatar
 
Join Date: May 2006
Location: Portland, Oregon!
2-way Unity Horn from 300Hz (some noob questions)
David -- the huge value for Vrc is because this is a sealed back driver, it's compliance is already determined by its built-in sealed back in its measurements. I made Vrc large because I didn't want that compliance reduced further by another back volume (that would really have no effect since the compliance is as low as it will ever be).

Is that not the right way to do that?
__________________
[W9MJE] Horn spreadsheet SynergyCalc/; SmallSyns SmallSyns;
Crossover design Xsim; Depot diffusor super-easy diffusors
  Reply With Quote
Old 3rd November 2017, 07:08 AM   #12
David McBean is offline David McBean  Australia
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by MrOIL View Post
As I have 2 ports per driver I now get 0,892062058076386cm Diameter per port...
Your calculation is correct :-).
__________________
www.hornresp.net
  Reply With Quote
Old 3rd November 2017, 07:37 AM   #13
David McBean is offline David McBean  Australia
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by bwaslo View Post
David -- the huge value for Vrc is because this is a sealed back driver, it's compliance is already determined by its built-in sealed back in its measurements. I made Vrc large because I didn't want that compliance reduced further by another back volume (that would really have no effect since the compliance is as low as it will ever be).

Is that not the right way to do that?
Hi Bill,

For your design, what you did makes complete sense.

I did not realise that MrOIL also intended using sealed-back drivers :-).

Kind regards,

David
__________________
www.hornresp.net
  Reply With Quote
Old 4th November 2017, 10:16 PM   #14
MrOIL is offline MrOIL  Germany
diyAudio Member
 
Join Date: Jul 2017
Location: Hamburg
I simmed it with ME now...
Pictures:
1 - synergy 3: Grey: normal, Red: 1300Hz 4th order Crossover
2 - synergy 4: Red: only Mid's
(The DE250 sim isn't accurate at all I think)

This is the best I could come up with... What do you think?
I want to build this thing after Christmas and I really don't wanna build ****!

Thanks in advance!
Attached Images
File Type: png synergy3.png (37.4 KB, 323 views)
File Type: png synergy4.png (29.8 KB, 317 views)
  Reply With Quote
Old 4th November 2017, 11:15 PM   #15
nc535 is offline nc535
diyAudio Member
 
Join Date: Apr 2011
Have you modeled the internal acoustic path of the CD? The sound penetrates into the CD some distance into the CD and reflects off its phase plug to cause a reflection null that limits mid bandwidth. I'm not sure what the distance is for the DE250. I would guess around 3 cm. If you can increase L12 by 3cm and still have adequate mid bandwidth, that is a good sign. You might also have a CD mounting plate whose thickness should be taken into account.

Is S1 really just 2.53 sq. cm.? You might start out building the horn that way but when you drill it out to 1" dia. you have 5.06 sq. cm.at the apex.
  Reply With Quote
Old 5th November 2017, 07:36 AM   #16
David McBean is offline David McBean  Australia
diyAudio Member
 
Join Date: Jun 2007
Quote:
Originally Posted by nc535 View Post
I'm not sure what the distance is for the DE250. I would guess around 3 cm.
(Specify using Ap1 and Lp).
__________________
www.hornresp.net
  Reply With Quote
Old 5th November 2017, 11:44 AM   #17
MrOIL is offline MrOIL  Germany
diyAudio Member
 
Join Date: Jul 2017
Location: Hamburg
After Reverse engineering the excel sheet I found that it was actually half of the needed value (5.06 cm^2). It impacts the whole horn geometry... And I thought I was finnished...
Will make some calculations today... Maybe write a small programm.
For the compression driver I think I got the right values now:
Ap1 = 4.23 cm^2
Lp = 2.5 cm
S1 = 5.06 cm^2
( Used this AkAbak script:
|Horn inside compression driver
Waveguide 'Wpp'
Node=300=400
dTh=2.32cm
dMo=1in
Len=3.0cm
Conical
|......dTh, dMo, Len)

Greetings!
  Reply With Quote
Old 5th November 2017, 02:27 PM   #18
nc535 is offline nc535
diyAudio Member
 
Join Date: Apr 2011
The spreadsheet contains an implicit assumption about how you will do the round to rectangular conversion. For a 1" exit driver, you are expected to design with a .707 square opening at the apex. After construction, you drill out that opening with a 1" diameter drill and then use modelling clay to do a tapering fill in the corners from the apex out almost to your mid ports. That isn't the only way to do it or the best but its the simplest I know of and seems to work.

If you want a challenge, 3D print a throat piece that matches the exit angle of your CD, does the round to rectangular conversion without need for modelling clay fill, and then mates up with your horn walls without interfering with mid placement.
  Reply With Quote
Old 5th November 2017, 02:37 PM   #19
MrOIL is offline MrOIL  Germany
diyAudio Member
 
Join Date: Jul 2017
Location: Hamburg
But then the throat would still be 5.06cm^2, right?

Image: The light blue stuff is beeing drilled away?
Attached Images
File Type: png synergythroat.png (25.2 KB, 277 views)
  Reply With Quote
Old 5th November 2017, 02:44 PM   #20
MrOIL is offline MrOIL  Germany
diyAudio Member
 
Join Date: Jul 2017
Location: Hamburg
Quote:
Originally Posted by nc535 View Post
If you want a challenge, 3D print a throat piece that matches the exit angle of your CD, does the round to rectangular conversion without need for modelling clay fill, and then mates up with your horn walls without interfering with mid placement.
I would be interested as I have acces to a machine... I think the exit angle of the de250 is 12; do you mean, that the adaptor should continue with that "expansion"?

Thanks.
  Reply With Quote

Reply


2-way Unity Horn from 300Hz (some noob questions)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
60-300hz other than horn loading noviygera Subwoofers 8 16th June 2017 06:25 AM
50-300Hz front horn arcgotic Multi-Way 29 22nd January 2016 01:26 PM
Questions on Synergy/Unity Horn rb132333 Multi-Way 26 9th October 2015 08:49 PM
Horn for <300hz? rvrazvan Multi-Way 5 19th August 2011 03:44 PM
searching for a 40hz-300hz bass horn patriz Multi-Way 8 1st November 2003 09:16 AM


New To Site? Need Help?

All times are GMT. The time now is 11:05 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki