back loaded horn design

[soundnovice]

i stumbled upon a link from Japan!
[ DIY ] Back loaded horn speaker design - Simple formula - DIY - Loudspeaker | Low-end Speaker Craft

in this a very simple way to design back loaded horn is explained with simple formula and diagram. the only speaker parameter required is Sd. no Fs or Qts even. i want to know if this is a reliable way of designing back loaded horns? at least for small full range drivers?

 

[GM]

Well, at least now I know why all those dinky little 'FR' BLHs tend to perform so poorly overall.....

Riddle me this; how good a performer will a vented speaker perform when all you use is step one and step two? You think adding a number of extra expansions is going to make it all come out right?

That said, no doubt there's a narrow range of speaker specs where it will work well, but reverse engineering it to find them isn't worth the effort, you'll do a lot better using Hornresp's Loudspeaker Wizard.

GM

 

[soundnovice]

i digged deep into this guys pages. here is another page where he explains the design empirically,
?????????[BH]?????(???)

 

[freddi]

he has a lot of ambitious designs - parallel blhs of different tuning, Pluvia 7 BP-duct damped horn subwoofer and other wild stuff.

 

[Scottmoose]

...in this a very simple way to design back loaded horn is explained with simple formula and diagram. the only speaker parameter required is Sd. no Fs or Qts even. i want to know if this is a reliable way of designing back loaded horns? at least for small full range drivers?

No.

 

[GM]

he has a lot of ambitious designs - parallel blhs of different tuning, Pluvia 7 BP-duct damped horn subwoofer and other wild stuff.

Reminds me of my efforts back in my teenie bopper days before I had a clue.........

GM

 

[globalplayer]

Reminds me of my efforts back in my teenie bopper days before I had a clue.........

GM

LOL!
Same.
Time flies...

 

[soundnovice]

now let me come to the issue here!

Boston Acoustics - HQ48002P - 8" Hi-Q Fullrange Driver - 8 Ohms - Pair

i have pair of these full range drivers. they are based on the vintage philips hi-q models. they are promising. believe it or not they are being used in Rethm's Bhaava speakers although with additional custom phase plug ( http://rethm.com/ )

as i understand Bhaava model also uses horn loading the full ranger. plus bass augmented with isobarik sealed 3 woofers!
but in all of Rethm models i know that full ranger is run full range. no crossover.
i want to build something similar. given my lack of knowledge with horn loading, can some one help me to design using these drivers?

Thanks

 

[GM]

OK, assuming the driver is driven with a low output impedance [<0.5 ohm] it has a theoretical ~75 Hz lower horn loading limit, so at 2.2 m + phase plug this is ~what the Rethm is apparently tuned to, though by calling it a 'Horn loaded labyrinth' where 'labyrinth' historically refers to TLs, I have to wonder if it's just a pipe horn like an inverted Terry Cain's 'BIB' corner horn except loaded with a phase plug.

Regardless, I'm thinking it's the way to go.

GM

 

[soundnovice]

so apart from complicated hard to understand mathsheets by MJK (please pardon my technical competency)....is there a calculator or tool which can help me design such a BLH?

 

[Scottmoose]

Hornrsp is probably the most straightforward, but you'll need to account for the crossover & bass units also.

 

[IG81]

+1 Hornresp. Takes a bit of getting used to, but it becomes pretty intuitive once you start messing with it IMO. There are online tutorials for it as well.

 

[soundnovice]

added the driver params and some initial params to the horn resp. not understanding how to calculate S1, S2 and S3 values

i have selected parabolic horn. so what would be the flare axial length for horn segment 1 and 2?
have selected 3.4L (3400cc) throat chamber volume. this i calculated based on driver Sd i.e. 200cm2

am i heading in right direction?

 

[GM]

Please attach the .txt export file for us to import.

GM

 

[soundnovice]

when i opened the hornresp, it for some reason didnt load the saved data. anyway i re-entered the details and exported
View attachment hiq.txt

 

[GM]

It didn't prompt you to save the file b4 closing HR?

GM

 

[David McBean]

Hi GM,

'soundnovice' has used the File > New menu accessed from the Input Parameters window to create a new data file named ps95, rather than just add the ps95 record to the default data file. The name of the new data file is included in the form caption - see attachment.

Depending upon the sequence of events used, it would seem that records are sometimes not being saved correctly to user-created data files.

I need to investigate further...

Kind regards,

David

 

[GM]

Greets!

Hmm, isn't this something similar to what I mentioned awhile back? I had some files that when I opened them I got an 'invalid result, change data' error, so had to create new files, but couldn't delete the bad ones.

Also, the driver specs for 'your' ps95 is actually the hiq.txt he just uploaded and I've [so far] successfully imported, used to make new files.

GM

 

[soundnovice]

before loading params for hi-q driver, i added params for dayton ps-95 also to understand the the interface. please ignore the name.

 

[soundnovice]

Hi GM,

'soundnovice' has used the File > New menu accessed from the Input Parameters window to create a new data file named ps95, rather than just add the ps95 record to the default data file. <snip>

if this is a real bug then do i qualify for any bug bounty?