back loaded horn design

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David McBean

Member
Joined 2007
hornresp.net
GM said:
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
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Hi GM,

Hopefully the problems you were experiencing were fixed some time ago.

As far as this latest issue is concerned, it turns out that records are being correctly saved to user-created data files after all :).

The comment "when i opened the hornresp, it for some reason didnt load the saved data." would tend to suggest that File > Open was not used to load the ps95 data file. The default data file would have been automatically loaded when Hornresp was started, which would explain why the desired ps95 record number 3 could not be found.

During my investigations however, I did identify a minor different bug which will be fixed in the next release.

Kind regards,

David
 
GM

GM

Member
Joined 2003
soundnovice said:
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?
View attachment 652634
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When designing a horn using T/S specs [as opposed to creating something with a 'slider' Wizard], this driver's super high Qts falls strictly into the small open baffle range, so a narrow bandwidth [BW] big vent reflex [AKA 'scoop bin'] is the horn equivalent.

If positioned in a corner, then the small vintage style cabs such as the Klipsch Rebel can be adapted to work well.

Note I just did a couple of 'quickie' one segment horns, so of course divide them up in whatever way its response comes closest to my sim [that you can easily build with flat panels of course].

Note too I changed the power handling to the published 25 W max and since these have a paper accordion surround, limited it to 0.5 mm Xmax, a typical limit for such designs, though will move a bit more before the VC starts leaving the gap.

GM
 

Attachments

  • HQ48002P_BLH.txt
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  • HQ48002P_Scoop.txt
    967 bytes · Views: 83
GM

GM

Member
Joined 2003
Walloffound said:
Is there a way to minimize this slap echo effect, like maybe putting a non reflective material on the parallel sides
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freddi said:
probably something like 3/8" felt - a piece at the top bend - maybe something in the "chamber" - then perhaps one sidewall. P10 and GM would know better than myself.
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The way I've mostly dealt with it is to add a foam horn extension ['soft' horn flare] to not only deal with the 'slap echo', but also the top/bottom, left/right eigenmodes at the mouth [terminus] that reflect back up to modulate the driver while most others either just ignore them or add some form of damping to 'trap' them inside the terminus [mouth], though does little/nothing for reflections back to the throat, hence the need for damping it to 'taste'.

A better solution if there's room is to add an actual extension flared out to the horn's cutoff area once any floor, etc., boundaries are accounted for [90 deg included for a parallel wall horn]. This will decay the 'slap echo', reflections back to the throat and also reduce the delay between the driver/horn's acoustic crossover, reducing the typical deep notch at its 3rd harmonic.

Of course, at least one of each parallel wall in the filter chamber will need damping, though I imagine most folks just stick a wad of polyfil or similar in it.

GM
 
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soundnovice

Member
Joined 2011
@GM: thanks for sims. but due to very high Qts (i am realizing it now!) i am guessing whether this driver is worth the effort. looking at scoop bin designs, they are meant for PA type applications and definitely not for home usage. its better i look for different drivers. i also came to know that same HiQ series have a driver model with Qts of around 1 which is much better i think. plus its Fs it 100hz which makes it attractive.
 
nigelwright7557

nigelwright7557

Member
Joined 2008
murtonpikesystems.co.uk
soundnovice said:
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?
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I found keeping it simple gave good results.
Simple closed box. No vents to allow over excursion.

In later years I did copy a Fane folded horn and liked the sound of that.
An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.
 
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soundnovice

Member
Joined 2011
foreveryoung said:
Sorry I don't really get what's the problem you are still stuck at as I haven't used hornrsp, but if you want to design a BL Horn, why don't you can use the free online service here
bgaudio.org

I use the formula by Nelson Pass here with great result PassDiy
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thanks for the bgaudio link. not sure how it calculates internally but it makes everything look simple. i put in specs for dayton ps95-8 4" full range driver. selected lowest freq as 70hz and performance/bw as 5.
and i got results as,
ps95_bgaudio.JPG
 
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