Speakerplans.com Homepage
Forum Home Forum Home > General > Newbie Discussion
  New Posts New Posts RSS Feed - Horn modelling
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Horn modelling
 Post Reply Post Reply
Author
Message
  Topic Search Topic Search  Topic Options Topic Options
yTho View Drop Down
Registered User
Registered User


Joined: 27 September 2018
Status: Offline
Points: 21 		Post Options Post Options   Thanks (0) Thanks(0)   Quote yTho Quote  Post ReplyReply Direct Link To This Post Topic: Horn modelling
    Posted: 11 October 2018 at 5:25pm
I'm looking to build a midtop using a 1" CD and a single 10" woofer with a conical horn. For the CD's I'm looking at, I need the woofer to reach to around 2.5/3k and also drop to 200Hz to meet my kicks.
In this example I've been working with Eminence Delta 10.
After too long on HR I eventually ended up with the frequency response that I've been looking for.
Problem is the dimensions are just plain dumb.


To get the response I need around 1-3k the throat has to ideally be 5-35cm2.


I've been working with the 'horn resp for.. dumm hmm everyone' guide

I'm confused as to exactly what Vtc/Atc and Lpt/Ap1 are.
Can someone give me an example of an enclosure that has Vtc/Atc?
In the image below I've circled the area where the cone meets the throat. Is this the Lpt/Ap1(150/1.8) or simply the S1(150xH)?

I've got a feeling I've got em mixed up making this model bin-able.
Back to Top
mobiele eenheid View Drop Down
Old Croc
Old Croc


Joined: 15 August 2004
Location: Netherlands
Status: Offline
Points: 1568 		Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2018 at 6:32pm
(Vtc) Volume Throat Chamber = Chamber between the driver and the horn
(Atc) Area Throat Chamber, Hornresp assumes a cylindrical model, so the Atc times the depth is equivalent to the Vtc. Most practically buildable horns don't comply with this model, so just make Atc larger than Sd and somewhat ball park right.

Length Port/ Area Port 1 = between the Vtc and horn, so typically the thickness of the baffle but in this specific design that was in-cooperated into the actual horn.

Vtc is really important, the rest less so (imo) but it also includes the volume of air "inside the cone" and is measured in cubic centimetres (1000 cc = 1 Litre). So let's say 500 - 1000 cc for a typical 10" driver.

Some pointers:

- Simulate in 4,0 pi
- Simulate directivity both on-axis and off-axis (great difference)
- Most horns aim at 3 octaves bandwidth so expect silly values if you hope to achieve much more
- Beyond 3 - 4 compression ratio is questionable for high output, not a problem for Hifi though
- Use a phase plug to limit Vtc (but that's beyond beginners scope)

Johan




Edited by mobiele eenheid - 11 October 2018 at 6:33pm
Back to Top
gen0me View Drop Down
Young Croc
Young Croc
Avatar

Joined: 20 February 2016
Location: UK
Status: Offline
Points: 999 		Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2018 at 7:01pm
This is your answer:
Originally posted by yTho yTho wrote:




2khz is way too high for modeling in hornresp for 10" driver.
You theoretically could just splash above picture. For your lowest picture Vtc would be Volume inside membrane cone + space in front of suspension. Atc would be as reasonable value(~Atc<Sd). Then S1 is where plywood starts: pi *(150/2)^2.
Dont expect much though.
I appreciate every like :)) https//www.facebook.com/genomesoundsystems
Mixes: https://www.mixcloud.com/gen-ome/
Back to Top
yTho View Drop Down
Registered User
Registered User


Joined: 27 September 2018
Status: Offline
Points: 21 		Post Options Post Options   Thanks (0) Thanks(0)   Quote yTho Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2018 at 7:59pm
Originally posted by gen0me gen0me wrote:

2khz is way too high for modeling in hornresp for 10" driver.

Is there other software i should be using for the 200-3k range I'm looking at?
Back to Top
gen0me View Drop Down
Young Croc
Young Croc
Avatar

Joined: 20 February 2016
Location: UK
Status: Offline
Points: 999 		Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 11 October 2018 at 8:00pm
FEA/BEM softwares.
Abec for example. You have to get into meshes.


Edited by gen0me - 11 October 2018 at 8:14pm
I appreciate every like :)) https//www.facebook.com/genomesoundsystems
Mixes: https://www.mixcloud.com/gen-ome/
Back to Top
yTho View Drop Down
Registered User
Registered User


Joined: 27 September 2018
Status: Offline
Points: 21 		Post Options Post Options   Thanks (0) Thanks(0)   Quote yTho Quote  Post ReplyReply Direct Link To This Post Posted: 12 October 2018 at 12:05pm
Originally posted by gen0me gen0me wrote:

FEA/BEM softwares.
Abec for example. You have to get into meshes.

Thanks I'll look into it.
Where would you say in the frequency range that HR is effective up to? And what makes you say its not useful past it?
Back to Top
yTho View Drop Down
Registered User
Registered User


Joined: 27 September 2018
Status: Offline
Points: 21 		Post Options Post Options   Thanks (0) Thanks(0)   Quote yTho Quote  Post ReplyReply Direct Link To This Post Posted: 12 October 2018 at 12:08pm
Originally posted by mobiele eenheid mobiele eenheid wrote:

- Simulate directivity both on-axis and off-axis (great difference)
- Beyond 3 - 4 compression ratio is questionable for high output, not a problem for Hifi though

 Thanks, can you just expand these two points for me?
Back to Top
mobiele eenheid View Drop Down
Old Croc
Old Croc


Joined: 15 August 2004
Location: Netherlands
Status: Offline
Points: 1568 		Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 12 October 2018 at 3:54pm

Compression ratio (under S1)


Directivity (under How high can you model before the results become inaccurate?)

Johan
Back to Top
gen0me View Drop Down
Young Croc
Young Croc
Avatar

Joined: 20 February 2016
Location: UK
Status: Offline
Points: 999 		Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 12 October 2018 at 7:04pm
Originally posted by yTho yTho wrote:

Thanks I'll look into it.
Where would you say in the frequency range that HR is effective up to? And what makes you say its not useful past it?

For example horn in my avatar is for 8" https://drive.google.com/folderview?id=1KiQ_gyjr-cOEU30OoIv1ByubH1jt04Yb. It was first drawn according to hornresp. Than I redrawn meshes for abec. BEM sims pretty confirmed that higher end response. Still there were some issues with the end of the horn, directivity, also there is bend that showed influence on higher end. It was good idea thought to get suggested by hornresp. Especially drawning this exponential entry part. Keep in mind that 8" is smaller so it should be easier to sim it higher without mistakes.
There were some things in this last part of the horn that were really hard to predict though.

Edit:
This was the hornresp sim before mesh changes:
All the values were reasoneable. If it goes to entrance it was 30cm^2 on the sim, vtc 119. There were some changes in entrance shape. There was some  small scalling too.
This horn could have as well closed rear


Edited by gen0me - 12 October 2018 at 8:22pm
I appreciate every like :)) https//www.facebook.com/genomesoundsystems
Mixes: https://www.mixcloud.com/gen-ome/
Back to Top
yTho View Drop Down
Registered User
Registered User


Joined: 27 September 2018
Status: Offline
Points: 21 		Post Options Post Options   Thanks (0) Thanks(0)   Quote yTho Quote  Post ReplyReply Direct Link To This Post Posted: 15 October 2018 at 8:04pm
Originally posted by mobiele eenheid mobiele eenheid wrote:

How high can you model before the results become inaccurate?)

After reading those posts, the graph is making more sense now..


Only thing is I cant select 'Directivity', its greyed out. Any ideas why?
Back to Top
mobiele eenheid View Drop Down
Old Croc
Old Croc


Joined: 15 August 2004
Location: Netherlands
Status: Offline
Points: 1568 		Post Options Post Options   Thanks (0) Thanks(0)   Quote mobiele eenheid Quote  Post ReplyReply Direct Link To This Post Posted: 15 October 2018 at 8:16pm
You should select output and then horn, before calculating the horns directivity. If you capture these results (control + c), you can overlay them with the combined response to see the total cabinet respons.

Also as mentioned, you should simulate in 4,0 pi ;)
Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.06
Copyright ©2001-2023 Web Wiz Ltd.

This page was generated in 0.109 seconds.