18'' Rear Loaded Horns designed with HORNRESP - help needed!! - 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 17th August 2011, 11:37 AM   #1
Kenel is offline Kenel  France
diyAudio Member
 
Join Date: Apr 2008
Default 18'' Rear Loaded Horns designed with HORNRESP - help needed!!

Hi everyone,

As previously said in other posts, I've already designed and built 2 Front Loaded Horns with 15'' drivers which sound great ! Thanks so much David for releasing and always improving HORNRESP.
To pursue my bass quest, I'm planing to build up 4 others bass bins with 18'' drivers but this time with Rear Loaded Horn. The aim is to get proximity response and bass pressure feeling with the direct radiating driver combined with the horn's long range abilities - not looking for a wide range of frequencies as usually in HiFi designs : 35-110Hz should be enough!
Some informations : Drivers are Precision Device PD186 / The design below is for a stack of 4 bins in half space.

First, I'm not sure to use HORNRESP correctly in case of a Rear Loaded Horns...
- regarding the 4 drivers in parallel in hornresp, to get the sensitivity of each box + 6 dB for the full stack, should I fix Eg = 2.83 v or 2.83x4=11.32 v?
In other words Eg=2.83 v gives the sensitivity of the complete stack (4 speakers) or hornresp assume that 2.83 v is provided to each speaker ?
- is a T=0.33 not too small… what are the incidences on the results?
- Vtc/Atc… I chose for Atc, the smallest section crossed by the waves going through the horn (Atc = S1). So that Atc also defines the limit of Vtc (minus the driver volume) - is that right?

About the results :
SPL looks correct to me even if some oscillations of +/-3 dB appears in the frequencies range (assuming that half space calculations is a bit rude). But what about the other results… some interpretations would help me a lot!
- Delta Phase response < 180° but pretty close to boundaries!!
- Group Delay??
- Acoustical Impedance??
- To get the combined response of the direct driver and the horn what length/distance should be enter in hornresp as the Horn Mouth and Driver are in the same plan? L=0m?
- Any other important recommendations?


Many thanks to everyone for this forum and the help provided…
Oliver
Attached Images
File Type: jpg BBC.RLH118_shape.jpg (28.8 KB, 362 views)
File Type: jpg BBC.RLH118_Hornresp_param.jpg (53.5 KB, 360 views)
File Type: jpg BBC.RLH118_Hornresp_SPL.jpg (112.2 KB, 350 views)
File Type: jpg BBC.RLH118_Hornresp_phase.jpg (45.0 KB, 337 views)
File Type: jpg BBC.RLH118_Hornresp_AcImpedance.jpg (120.2 KB, 329 views)
File Type: jpg BBC.RLH118_Hornresp_GpDelay.jpg (38.4 KB, 44 views)
File Type: jpg BBC.RLH118_Hornresp_Impedance.jpg (102.3 KB, 40 views)
  Reply With Quote
Old 17th August 2011, 01:26 PM   #2
diyAudio Member
 
Join Date: Jan 2011
35-110 seems like a pretty large range of frequencies for a subwoofer....check out the TH-18 possibly, it is geared towards live sound but it covers the range you want, and was originally designed for the PD1850 driver.
And use 2.83 not 2.83 x 4....
Any reason for wanting a rear loaded horn as opposed to a tapped horn?
  Reply With Quote
Old 17th August 2011, 02:32 PM   #3
epa is online now epa  Netherlands
diyAudio Member
 
Join Date: Apr 2010
Location: amsterdam
combind responce could be set as 0.
looking at the input data the mout area = verry big 1.5 m2=~3'*5'
edit/ i see its 4 cabs.
if u use 4 cabs ,just use 1 paralel speaker @ 0.5 pi(same result)
__________________
one good thing about music ,when it hit you feel no pain.
so hit me with music
.

Last edited by epa; 17th August 2011 at 02:35 PM.
  Reply With Quote
Old 17th August 2011, 03:03 PM   #4
epa is online now epa  Netherlands
diyAudio Member
 
Join Date: Apr 2010
Location: amsterdam
for a f3 of 35 hz increase the pathlengt by 70 cm.
side note ,rlh always have a big dip in this case ~ 100 hz(this is why people think they go real low,but in reality they fall of @ 50 or so)
__________________
one good thing about music ,when it hit you feel no pain.
so hit me with music
.
  Reply With Quote
Old 17th August 2011, 09:03 PM   #5
Kenel is offline Kenel  France
diyAudio Member
 
Join Date: Apr 2008
Thanks for your answers,

Quote:
Originally Posted by m R g S r View Post
Any reason for wanting a rear loaded horn as opposed to a tapped horn?
Mainly because I've never listen a Tapped Horn in PA conditions yet - whereas I heard a lot of RLH and I really like the pressure effect of the direct radiator at about the height of the thorax. Shaking style But the Tapped Horn idea is very interesting and maybe for my next build! wait and ear... but I want to ear first - according to my simulations, my last Folded horns where supposed to cover 35-100 Hz and I've never eared anything below 50 Hz... probably because the speakers and T&S parameters didn't describe properly the real response under 80 Hz. So that I decided to build new RLH with 18'' and more particularly for the PD186 because of their response in BF.

Quote:
Originally Posted by epa View Post
for a f3 of 35 hz increase the pathlengt by 70 cm.
side note ,rlh always have a big dip in this case ~ 100 hz(this is why people think they go real low,but in reality they fall of @ 50 or so)
Hard to find 70cm with this horn path... can you tell me more about the falling @ 50Hz... for me the 100Hz dip still a myth...

Anything to say about the Group Delay / Acoustical Impedance??
  Reply With Quote
Old 18th August 2011, 03:36 PM   #6
epa is online now epa  Netherlands
diyAudio Member
 
Join Date: Apr 2010
Location: amsterdam
here is your fr sim.
i moddeled a double flared rlh many years back, these were huge cabs and went lower than the usual scoops.
im trying to find the sim.
the dip is caused where the back wave meat's front wave .
Click the image to open in full size.
__________________
one good thing about music ,when it hit you feel no pain.
so hit me with music
.
  Reply With Quote
Old 18th August 2011, 05:38 PM   #7
epa is online now epa  Netherlands
diyAudio Member
 
Join Date: Apr 2010
Location: amsterdam
everything else looks fine,i like the impulse responce.
__________________
one good thing about music ,when it hit you feel no pain.
so hit me with music
.
  Reply With Quote
Old 24th August 2011, 09:59 AM   #8
Kenel is offline Kenel  France
diyAudio Member
 
Join Date: Apr 2008
Sorry for the delay... few days off!
Thanks a lot for your answer epa and especially for the sim.
So as I've also seen on some measurements, the 145Hz dip of the back & front waves crossing is real but high enough to be out of the working frequency range. By the way your sim shows a nicer SPL than I expected - even if the FR is reduced to 45-100Hz - but are you sure that the EXP horn you simulated is equivalent to the HYP parameters I used?
Quote:
Originally Posted by epa View Post
everything else looks fine,i like the impulse responce.
Nice but what do you precisely mean by the impulse response?
  Reply With Quote
Old 24th August 2011, 06:29 PM   #9
epa is online now epa  Netherlands
diyAudio Member
 
Join Date: Apr 2010
Location: amsterdam
first have to say the dip wil be @ 110 if you extend your horn path 70 cm and @ 140 or so in your example.
hyperbolic or exponential doesn't make a difference.
in the pic i plotted the black line =exp and the grey line= hyp.
as you can see no difference
impulse is how long it takes the box to respond and to quiet down after a signal.
so a tight sound if you will in your case.
Click the image to open in full size.
the good news is the pd won't exceed x-limit @1000 watts @30 hz.
and yes verry efficient design indeed.
those pd drivers are beasts
__________________
one good thing about music ,when it hit you feel no pain.
so hit me with music
.

Last edited by epa; 24th August 2011 at 06:34 PM.
  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
Info needed about Expo-Falthorn or Rutsche rear loaded horns? Norris Wilson Full Range 1 30th June 2011 04:01 PM
How to model Back Loaded horns in Hornresp? Boscoe Full Range 2 17th January 2011 08:00 AM
My 103E Rear loaded horns shporsche Full Range 17 15th July 2009 11:16 PM
Rear-loaded horns: disadvantages? Taterworks Full Range 4 3rd October 2007 05:22 PM


New To Site? Need Help?

All times are GMT. The time now is 09:16 AM.


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