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Wirrunna

Chief Bonehead on the AK6 K Horn

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I wonder if horns are subject to the "end correction" practice (?) (theory?) that is used to fine-tune vents and T/Ls. The end correction for vents is usually assumed to be the length that is equivalent to the circumference of the vent. In other words, the mass of air existing the vent is, for some distance, still about as compact as it is inside the vent, and therefore the effective vent is longer than the calculated vent, meaning the vent tube must be shortened. 

 

I would think this would not apply to the Klipschorn, unless we count the distance across the front of the bass bin where the two horn paths converge.

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sixspeed wrote: "The KHorn now has the rear panel sealed since the 70th editions. That is likely where the extra length of the horn is coming from."

 

Nope, unless the enclosed Klipschorn is located in a corner (where it belongs), you will lose at least 12" of the final horn expansion.

 

Chief bonehead wrote, "Actually it’s about 97.3765”......approximately."

 

Attached are some drawings of one of my Klipschorn bass cabinets. I came up with a throat-to-mouth distance of 70.33333333".....approximately.

 

Where's the extra 24+ inches?? Surely you aren't counting the path from H to I twice?

 

Regards,

 

Lee

 

 

Path length.jpg

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While it wouldn't account for ~30 additional inches, I'd say your "G" spot is in the wrong location (is it hard to find?).  I'd put it midway on the middle horizontal member in the side view.

 

And "I" seems somewhat arbitrary.  A case could me made for it being on a line perpendicular from the wall to the edge of the cabinet (resulting in a loss). 

 

Could also be a "J" from your current "I" (the pair of them) some distance in front of the enclosure center point...

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I agree with Lee's diagrams, except that I would put point I much farther back, as in I' in the diagram below. Even that's being "acoustically generous", because the horn actually starts to lose control at point J'.

Image1.png

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At a minimum in terms of change, the path from G to I should be figured on the plane slope from G to the point of the splitter (near B in the side view.  Assuming G to I was initially figured horizontally this would add a few inches.

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Both glens and Edgar make good points. The path (A to I) was chosen more from a measured midpoint at key points along the horn.  Once you remove the tailboard and the woofer access door, you can measure just about any distance, dimension and angle. Well, you do have to remove the "bug screen". 'Bout the only thing I couldn't begin to calculate is the rear chamber volume.

 

Obviously, there are longer and shorter paths from the throat to the mouth. Sorry to hear the Klipschorn loses control at point J . :>(.  Maybe Chief bonehead can "horn in" re where he thinks the mouth is.  

Tomorrow, I'll set up ARTA and do some path length measurements.  Ivo Mateljan (the author) has just released the latest version. There is a trial version you can download but a licensed copy is only 79 Euros. Great (newly revised) user manuals, too.

 

Lee

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What's the point in debating over how the length of the Klipschorn bass horn is calculated?  Do you think you know more about it than Chief Bonehead?  The K-horn gets the job done, as it has for over 70 years.  Suggesting that the top engineer, the person who comes up with the improvements to the classic design, may be doing something deceptive in the description of the horn is pretty rude.  Saying you're not clear on how the measurement is arrived at would be one thing, and it seems to be exactly what's going on here, but to suggest that there may be "deceptive advertising" taking place makes it look like it might be a great idea to think things through before making accusations like that.

 

The length of the bass horn is what it is.  What would be the use of describing it incorrectly?  It wouldn't change the performance of the horn or of the whole speaker.  The K-horn's performance has improved over the decades, with minimal changes to the cabinet, other than the closed back.  There has never been a change of roughly two feet in the bass horn length, so it's clear that you're not clear on how the length is measured.

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No accusations on my part.  I merely find it interesting.  Oftentimes stuff like the other video referred-to is not put together by the engineering staff, so there's that.  A statement may be incorrect but that doesn't necessitate deception.

 

A test of differential times for sound propagation not through crossovers should answer any question about relative path lengths not answered directly by one of the engineering staff in the know.  For those who are interested in knowing such information.

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5 hours ago, Islander said:

The length of the bass horn is what it is.

 

By the same token, it isn't what it isn't. The internal path length isn't 8 feet. The "8 foot" horn length claim may be justifiable; if so then it needs to be explained.

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I once read a quote by PK regarding 100 sq inches and the rubber throat - any chance things are getting conflated?

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14 minutes ago, Deang said:

I once read a quote by PK regarding 100 sq inches and the rubber throat - any chance things are getting conflated?

 

I don't think so. IIRC, I have some old advertising copy from the 1970s that makes the "8-foot folded horn" claim, so it's been around for quite a while.

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3 hours ago, glens said:

No accusations on my part.  I merely find it interesting.  Oftentimes stuff like the other video referred-to is not put together by the engineering staff, so there's that.  A statement may be incorrect but that doesn't necessitate deception.

 

A test of differential times for sound propagation not through crossovers should answer any question about relative path lengths not answered directly by one of the engineering staff in the know.  For those who are interested in knowing such information.

 

Actually, my comments were directed to Arkytype, who was the person who used the phrase "deceptive advertising".  He seems to have started the wagon rolling, and some others have jumped on.

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I'd like to see measurements of the different enclosures and placements that people have done over the years to see if there is a significant difference. I just purchased a Umike-1 so as soon as I get set up I'll be measuring my closed back K-Horns

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1 hour ago, Islander said:

 

Actually, my comments were directed to Arkytype, who was the person who used the phrase "deceptive advertising".  He seems to have started the wagon rolling, and some others have jumped on.

 

What I wrote, "Hope Klipsch isn't resorting to deceptive advertising." was written partly in jest. Should I have attached a smiling emoji at the end?

 

With all the puffery associated with most audio product advertising, I was very surprised to hear the voice over of the animated Klipschorn state,  "The key to the Klipschorn's deep bass and high efficiency starts with its eight-foot folded horn low frequency cabinet." 

 

About the only thing on my Klipschorn that measures 8 feet is its circumference, not the length of its acoustic path. I'll be making some acoustical measurements later today that might clear up the matter. 😊😊😊😊😊😊😊😊😊

 

 

Lee

 

 

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Personally I don't care how long the length of the basshorn is.... 70", 80", 90", 100"... whatever. All I know is that the sealed cabinet sounds AWESOME. So whatever Klipsch did, they got it right.

 

I think they did a great job retaining everything what makes the KHorn a KHorn all while making very tasteful and relevant improvements to the design to keep it competitive as a flagship speaker in a tough market.

 

I'm just grateful to be fortunate enough to be able to own them.

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I've now both physically measured the path length of one of my Klipschorn bass cabinets and, using the Impulse Response tool within ARTA, made many measurements of not only the bass horn's path length (varying sample rate, chirp length, etc. but also measured (and confirmed) the path length of known distances between a Beyma CP-25 tweeter diaphragm and my 1/2" Bruel & Kjaer 4133 microphone. Since ARTA allows one to enter the room temperature and humidity to change the default speed of sound (344 meters/second), measurements and calculations were made using 346 m/sec.

 

Here's how to read the data block. The cursor located just before the positive-going peak is at 6.484 milliseconds after time zero. Since all AD->DA converters as well as FIR filtering has latency, we must count our starting time not from 0.00 milliseconds but (in the case of ARTA) at sample position 300. Note that the cursor is at sample position 1245. Sample position 300 represents a system latency of 1.557 msec + or -.

 

The time (path length) we are interested in is the gate time which is simply the difference between the cursor location (6.484 msec) and sample position 300 (1.563 msec). A gate time of 4.927 msec converts to a path length of: (34.6 cm/1 msec) =(X cm/4.927 msec) ; X = 170.47 cm  or 67.11 inches.   

 

So, where does that leave the issue of the claimed "8-foot folded horn low frequency cabinet."? 

 

Lee

                                                              

 

 

 

Klipschorn path length  measurement.jpg

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11 hours ago, Arkytype said:

So, where does that leave the issue of the claimed "8-foot folded horn low frequency cabinet."?                                   

 

 

There's all kinds of pedantic but unimportant analysis that could be performed, concerning the difference between driver offset and horn length, but I'm not going there. Really, the only important thing is that the path length is not 8 feet.

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On 4/21/2019 at 12:41 AM, Chief bonehead said:

Actually it’s about 97.3765”......approximately. 

I'm glad you still have a great sense of humor instead of getting cranky in your older age!

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