Klipsch Bass Horn Acoustic Analysis

[Arkytype]

Single path Klipschorn

David, et al,

How would Hornresp model a single path Klipschorn? All things being equal (and of course they are not), wouldn't you have only a 3 dB loss in acoustic power output?

Correct me if I'm wrong, but don't the horn equations used by Olson, Beranek, Keele, Leach for their examples are counting on a single pathway with predictable area vs. horn length?

The Klipschorn's woofer doesn't "see" a a single path of exponential area expansion with a mathematically predictable output.

Lee

 

[Ivo]

I understand your question, and I don't have the mathematical answer. Over time I have learned that two "half" horns together behave as one full horn. So you either sim as one horn, or simulate multiple enclosures. The OP did neither, so he sims something else than the Khorn. What he finds is interesting nonetheless.

 

[whgeiger]

errata

Two possible explanations come to mind for throat variances addressed here and they are not necessarily mutual exclusive nor do they lead to making an immediate choice regarding superiority of a particular configuration:

1) Over the production life of this enclosure, which has certainly been protracted, I am sure the parameters of the driver used have undergone changes that have required modification of horn acoustics that are easily implemented by alteration of throat dimensions. Thus, to make the right choice requires specification of a particular set of driver parameters and their tolerances only known to the folks at Klipsch.

2) These minor differences may also be due to individual voicing of each unit before final assembly, base on measured driver parameters of the specific unit to be married to a standard horn body by using different throat sub-assemblies to achieve a superior match.

WHG

Due to my scan read of post text, I misunderstood the issue raised. At the frequencies of interest and simulation software used, the horn should be treated as a whole even though bifurcated. There is a discontinuity at the horn/room interface. This only becomes an issue when wavelength approaches and becomes smaller than the extent of the discontinuity. Here it is no longer acoustically transparent. WHG

 

[David McBean]

David, et al,

How would Hornresp model a single path Klipschorn?

Sorry - I don't understand what you mean by a single path Klipschorn.

 

[Ivo]

I think Arkytype assumes that a half Khorn, one of the pathways, has a different expansion and acoustical properties than a "double" pathlength.

 

[Arkytype]

Single path clarification

Upon reflection, just blocking the upper or lower acoustic path at the splitter wouldn't create a single path horn. You'd have to block the rear of the horn
so that the area & volume for calculations would be correct.

So, let's say you modeled the (now modified Klipschorn bass cabinet) as a single path horn with the 3" x 12.5" throat opening and a mouth dimension of 13" x 18.5". Would the Hornresp model be different than trying to model a bifurcated horn?

Bifurcated: The woofer "sees" a path with an expansion rate double that calculated using traditional formulas.

Single Path: The woofer "sees" a path that expands in a manner consistent with calculations.

Are there horn formulas that allow for a bifurcated path?

Lee

 

[whgeiger]

False Assumption

Upon reflection, just blocking the upper or lower acoustic path at the splitter wouldn't create a single path horn. You'd have to block the rear of the horn
so that the area & volume for calculations would be correct.

So, let's say you modeled the (now modified Klipschorn bass cabinet) as a single path horn with the 3" x 12.5" throat opening and a mouth dimension of 13" x 18.5". Would the Hornresp model be different than trying to model a bifurcated horn?

Bifurcated: The woofer "sees" a path with an expansion rate double that calculated using traditional formulas.

Single Path: The woofer "sees" a path that expands in a manner consistent with calculations.

Are there horn formulas that allow for a bifurcated path?

Lee

Sl0 = (St1 + St2)*e^(ml/2) = St0*e^(ml/2) where St0= St1+St2 (the bifurcated throats). Here [m] and [e] are constants, so the flare rate is the same. Also bifurcation is acoustically transparent except at high enough frequencies where the un-joined bifurcated mouths behave as dual sources. WHG

 

[whgeiger]

From the Past

is the work of Rayleigh. Maybe this might help. WHG

 

[David McBean]

So, let's say you modeled the (now modified Klipschorn bass cabinet) as a single path horn with the 3" x 12.5" throat opening and a mouth dimension of 13" x 18.5". Would the Hornresp model be different than trying to model a bifurcated horn?

Hornresp doesn't know or care if a horn system is bifurcated - it makes no difference to the analysis.

For the reasons given in Post #179, the only way to accurately simulate a Klipschorn, or any other single-driver bifurcated bass horn loudspeaker for that matter, is to consider the complete system, not just one half of it.

A simple exercise in Hornresp clearly demonstrates this. The attachment compares the response of a Klipschorn-type loudspeaker radiating into 1.0 x Pi space (black trace) to that of one half of the system with the same driver, radiating into 0.5 x Pi space (grey trace).

 

[jimmosher]

Hi Jim,

A Klipschorn bass corner horn should be modelled in Hornresp full-size. If only one half of the system is considered, the driver parameter values need to be altered and the solid radiation angle specified as 0.25 x Pi steradians (sixteenth space) to obtain the correct results. Even if adjusted driver parameter values can be determined, the required Ang value is not supported by the program.

Kind regards,

David

Hi David,

I hope that post #135 shows that I used the full size of the K-horn when modeling the optimum horn shape.

Jim