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15 minutes ago, moray james said:

if folks are really concerned about bifurcation then they can always opt to eliminate it by building a horn that does not have it as part of its design. The University Classic and Dean are both highly respected still today (though larger than a LaScala) here is another option not much larger than a LaScala but with more to offer. I will also attach a single driver version of this horn for those who want something smaller.

 

Moray, When a horn has a different length for the "inside" and "outside" paths, then the cabinet (horn) will act as a lowpass filter The diagram you showed has a large difference in the two "lengths". Bifurcating and careful folding can help minimize the discrepancy (and degree of filtering), and do this is in a reasonably sized package.  

 

So bifurcated horns do have their place and the problems with dispersion will need to be addressed, minimized or worked around. It is one of many design compromises inherent in the product.

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28 minutes ago, PrestonTom said:

 

I will give you the benefit of the doubt.

 

Thank you.

 

Quote

 

Perhaps you are referring to the differing path lengths that occur when a horn is "folded". Yes, those do matter and when they are very different the cabinet can then act as a low pass filter. Is this what you mean by lobing in the the two pathways?

 

This issue of dispersion with a bifurcated horn is real and does have consequences. 

 

I'm thinking that directly on-axis of the horn (LaScala in mind), within construction tolerance limits, little to no lobing would appear.  However, for any wavelength which is great enough for continued expansion beyond the point of the doghouse there will be interference patterns developing.  Just saying...

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11 minutes ago, PrestonTom said:

Moray, When a horn has a different length for the "inside" and "outside" paths, then the cabinet (horn) will act as a lowpass filter The diagram you showed has a large difference in the two "lengths". Bifurcating and careful folding can help minimize the discrepancy (and degree of filtering), and do this is in a reasonably sized package.  

 

So bifurcated horns do have their place and the problems with dispersion will need to be addressed, minimized or worked around. It is one of many design compromises inherent in the product.

yes I simply wanted to offer an alternate which was similar in overall build but which bypassed issues seen by some builders. I agree that with good design bifurcation can have minimal impact. Thanks.

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2 minutes ago, glens said:

 

Thank you.

 

 

I'm thinking that directly on-axis of the horn (LaScala in mind), within construction tolerance limits, little to no lobing would appear.  However, for any wavelength which is great enough for continued expansion beyond the point of the doghouse there will be interference patterns developing.  Just saying...

LaScala starts to roll around 140 Hz and is best rolled off around 90 Hz in a multi way system. The design is very symmetrical from throat to mouth. Extending the point of the doghouse to the front edge of the cabinet would help a little I expect it would show on a measurement but I am not sure it would be noticeable. The edge is not flush for practical reasons (in pro versions) but overall it has been and still is a very well accepted design especially given its compact size.

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I'm a fan of the design.  I entered this thread being goaded into it by what I'd felt was sub-optimal information regarding the term "bifurcation."

 

That aside, any time you've got two pathways for the same information there are going to be consequences somewhere somehow.

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13 minutes ago, glens said:

 

Thank you.

 

 

I'm thinking that directly on-axis of the horn (LaScala in mind), within construction tolerance limits, little to no lobing would appear.  However, for any wavelength which is great enough for continued expansion beyond the point of the doghouse there will be interference patterns developing.  Just saying...

 

No disagreement there, but isn't that the problem for any horn that is "too short". The longer wavelengths will "see" an incomplete "matching of impedance" from the horn and will be partly reflected back to the mouth. This resulting in the peaks and dips at the  output.

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1 hour ago, PrestonTom said:

Moray, When a horn has a different length for the "inside" and "outside" paths, then the cabinet (horn) will act as a lowpass filter The diagram you showed has a large difference in the two "lengths". Bifurcating and careful folding can help minimize the discrepancy (and degree of filtering), and do this is in a reasonably sized package.  

 

So bifurcated horns do have their place and the problems with dispersion will need to be addressed, minimized or worked around. It is one of many design compromises inherent in the product.

 

Any fold will act as a low pass filter unless it has rounded bends on the inside and outside of the turn (fold).  Shorter waves (higher frequency) will bounce back starting at 2-300 Hz, a reflector may gain you a bit but a true waveguide (properly rounded bends inside and outer radius) will allow the shorter waves to pass without bouncing back.

 

 

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3 hours ago, ClaudeJ1 said:

Would "naked 1/4 wave horns" be a more accurate term rather than "tapped horns." Boy could we ever make some human reproductive entertainment  analogies with those words, eh?

 

The term was coined already, too late now.:D

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5 minutes ago, jason str said:

 

Any fold will act as a low pass filter unless it has rounded bends on the inside and outside of the turn (fold).  Shorter waves (higher frequency) will bounce back starting at 2-300 Hz, a reflector may gain you a bit but a true waveguide (properly rounded bends inside and outer radius) will allow the shorter waves to pass without bouncing back.

 

 

This sounds like the "ray tracing" view of corner reflectors.

The other view, stresses the importance of an ever-expanding cross-sectional area along with minimizing the difference between the inner an outer path lengths. I put more emphasis on the second view. 

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2 minutes ago, PrestonTom said:

This sounds like the "ray tracing" view of corner reflectors.

The other view, stresses the importance of an ever-expanding cross-sectional area along with minimizing the difference between the inner an outer path lengths. I put more emphasis on the second view. 

 

How many folded horns have you seen crossed over above lets say 1000 Hz ?

 

 

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3 minutes ago, jason str said:

 

How many folded horns have you seen crossed over above lets say 1000 Hz ?

 

 

I am not sure what this means.

My understanding is that the Low pass nature of the La Scala and K-Horn (400 or so Hz)is due to the problems I cited. This was resolved in the Jubilee and allowed the cabinet to go about an octave higher. 

 

If you are interested, draw out a life size sketch of the horizontal of the Jubilee and then plot the both the cross sectional area as a function of distance (along the horn). Also plot the path lengths for the "inside" and "outside". Take the difference and you will see where that is maximum (and how it is then re-aligned in the final sections). Hint: the back fold is critical. 

 

The jubilee has some very interesting features in its geometry. I guess Roy knew what he was doing .......

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13 minutes ago, jason str said:

 

How many folded horns have you seen crossed over above lets say 1000 Hz ?

 

 

for me none so far as I am aware. It is not desirable for a horn to have very wide bandwidth beyond where you mid takes over as you would end up with a lot of bass horn to mid horn interference. For a reasonable size compromise so far as mid horn size goes 600Hz would be about as high as I would ever think and higher than I would not want. I have not seen a bass horn that can go that high up, the best I have ever seen that has builds to confirm performance is Ernst Georg Beck's California see the attachment.

Ernst georg Beck bec1fr.jpg

Ernst Beck California horn.gif

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4 minutes ago, PrestonTom said:

 

I am not sure what this means.

My understanding is that the Low pass nature of the La Scala and K-Horn (400 or so Hz)is due to the problems I cited. This was resolved in the Jubilee and allowed the cabinet to go about an octave higher. 

 

If you are interested, draw out a life size sketch of the horizontal of the Jubilee and then plot the both the cross sectional area as a function of distance (along the horn). Also plot the path lengths for the "inside" and "outside". Take the difference and you will see where that is maximum (and how it is then re-aligned in the final sections). Hint: the back fold is critical. 

 

The jubilee has some very interesting features in its geometry. I guess Roy knew what he was doing .......

 

Can the Jubilee bass bin make a clean pass to 1000 Hz ?

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3 minutes ago, moray james said:

for me none so far as I am aware. It is not desirable for a horn to have very wide bandwidth beyond where you mid takes over as you would end up with a lot of bass horn to mid horn interference. For a reasonable size compromise so far as mid horn size goes 600Hz would be about as high as I would ever think and higher than I would not want. I have not seen a bass horn that can go that high up, the best I have ever seen that has builds to confirm performance is Ernst Georg Beck's California see the attachment.

Ernst georg Beck bec1fr.jpg

Ernst Beck California horn.gif

 

A higher crossover point will allow more HF & 2 way options.

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3 minutes ago, jason str said:

 

Can the Jubilee bass bin make a clean pass to 1000 Hz ?

no a Jub cannot play out to 1KHz  and cross over to a mid horn. a Khorn starts to get into the soup at about 325 Hz., that's why it was a bad candidate for a two way the horn for the mid would have to be massive, way to large for the general public to swallow.

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5 minutes ago, jason str said:

 

A higher crossover point will allow more HF & 2 way options.

a higher crossover point will result in a host of bad interactions between the bass horn and the mid if what you suggest was a plan you would see speakers built that way and we don't. It is not a good idea. Besides it is not possible for a horn to have such range it is not possible it does not work.

Peavey designed a somewhat better LaScala and claimed it could be crossed at 600Hz (for pa applications) it does not in fact make 600 Hz and it has essentially the same bass response as a LaScala does so it's not full range.

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3 minutes ago, moray james said:

a higher crossover point will result in a host of bad interactions between the bass horn and the mid if what you suggest was a plan you would see speakers built that way and we don't. It is not a good idea. Besides it is not possible for a horn to have such range it is not possible it does not work.

 

It is possible and has been done already.

 

Manufactures just wont invest in the extra steps it takes.

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15 minutes ago, jason str said:

 

A higher crossover point will allow more HF & 2 way options.

can you show me a bass horn with the same low end response and a higher roll off? I wont be holding my breath while you search. I have looked for years and never found one. This (the Beck California) is so far as I am aware of has better bandwidth than a Jub. this will be a better sounding horn than a Jub as well. The jub has the lopped of front like a Belle does, the foreshortened dog house, the part which is intended to integrate the two wave halves and so the two halves of the bifurcated horn do not integrate as well as a horn lie the California or the University Classic or Dean horns will. Consider the size physical of the mouth of the Jube or the California and then consider the lobbing above say six hundred hertz a little over 22 inches and you can imagine the mess that happens to you stage and image at frequencies there and above.

 

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2 minutes ago, moray james said:

can you show me a bass horn with the same low end response and a higher roll off? I wont be holding my breath while you search. I have looked for years and never found one. This (the Beck California) is so far as I am aware of has better bandwidth than a Jub.

 

Low end should be crossed over to a subwoofer as far as I'm concerned if you want to hear all of your recorded content.

 

Any of the BFM DR series will get you there. Porting the cabinets can get you by if a sub is out of the question.

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