Corner-Horn Imaging FAQ

[Guest " "]

Dear Abby

What about flipping the khorn base bin upside down so that the horizontal top section that was intneded to support the top section is now on the floor. Electro-Voice did this on a lot of their Klipsch licensed Khorns. Does this really improve mid bass performance?

[Chris A]

What about flipping the khorn base bin upside down so that the horizontal top section that was intended to support the top section is now on the floor. Electro-Voice did this on a lot of their Klipsch licensed Khorns. Does this really improve mid bass performance?

I am not familiar with this story: are you talking about turning just the bass bin 90 degrees or 180 degrees? It's symmetric in 180 degrees.

Chris

[Chris A]

"How Many Absorption Panels Can I Use at the Front of the Room?"

 

One of the comments that Roy Delgado made about smooth near-field room boundaries (or the absence of those boundaries altogether) improving corner horn imaging has interesting implications. There are "acoustics experts" that mention that the use of absorption is to be avoided wherever possible in small rooms--that it is better instead to use diffusion panels. Yet, Mr. Delgado states clearly that the best situation for imaging performance is "total absorption" or no reflections at all.

If you place diffusers in the early reflection areas around your speakers, you will effectively have what I had (brick masonry around my fireplace) that caused all of my imaging issues to begin with.

 

By ignoring the sage advice about avoiding absorption and put up absorption panels around the front of the listening room, I found that the taboos on in-room absorption were too widely generalized. [Note that putting too much absorption around a room, if taken to the extreme, will result in an anechoic chamber--which is a terrible place to listen to speakers (...try it...).] So the issue is "what kind of beneficial reflections are we looking for?

 

On the subject of imaging in corner-horn speakers such as Klipschorn Jubilees, the verdict is clear: minimize reflections around your corner horns and between the speakers. The room will feel a little smaller, but imaging performance will go through the roof. This is a good trade in relative loss of "ambiance" vs. increase in imaging. The rest of the room's reflective surfaces outside of the early reflection areas have more than adequate surface area to retain a sense of room spaciousness.

 

If your room is especially long like mine - absorbing front-room reflections emphasizes longer duration reflections from the back of the room, leading to a greater sense of lf response from corner-loaded subwoofers, which operate well below the effective absorption frequency band of the acoustic tiles--an unexpected and pleasant effect. I would hazard that ceiling-mounted absorption panels would further increase imaging performance, but I haven't done the experiments (...which of course will require the absence of WAF to avoid anxiety attacks).

 

One experiment (since made permanent) was the re-aiming of the K-402 hf horn downward directly at the listening position (there is an adjustment mechanism and vertical scale built into K-402 horn base to do this). This reduced first reflections from the ceiling and resulted in a slight coalescing of the stereo image vertically, with resulting greater imaging presence.

 

Acoustic absorption tiles placed around the side-wall horn exit and front-wall reflective surfaces to control early reflections from corner and center speakers.

[fini]

Only question: what does BJT stand for? Thanks.

Larry

I was gonna guess bacon, jelly and tomato.

[Guest " "]

What about flipping the khorn base bin upside down so that the horizontal top section that was intended to support the top section is now on the floor. Electro-Voice did this on a lot of their Klipsch licensed Khorns. Does this really improve mid bass performance?

I am not familiar with this story: are you talking about turning just the bass bin 90 degrees or 180 degrees? It's symmetric in 180 degrees.

Chris

There are a few EV models (klipsch licensed Khorns) that actually flip the bass bin upside down resulting in the horizontal shelf where the top section normally sits on, bieng on the floor. What happens now is that the sound goes higher into the corners and that changes the way the khorns sound.

[Chris A]

Gotcha.

I remember watching a video on the 60th Anniv. Khorn (i.e., enclosed backs) where the then-director of Klipsch sales took credit for the idea of enclosing the backs, but mentioned that, contrary to intuition, the Khorn bass cutoff frequency actually went higher (i.e., wrong direction) than the non-enclosed back. I deduced from this that the Khorn bass bin actually benefits from having a little leakage around the top collar between the bass bin and top-hat sections, but there is no benefit from leakage across the tailpiece.

Interesting. EV actually marketed it as a "feature"... interesting.

Chris

[LarryC]

Only question: what does BJT stand for? Thanks.

Larry

I was gonna guess bacon, jelly and tomato.

Or __ Time

[Guest " "]

Gotcha.

I remember posting on the 60th Anniv. Khorn (i.e., enclosed backs) where the then-director of Klipsch sales took credit for the idea of enclosing the backs, but mentioned that, contrary to intuition, the Khorn bass cutoff frequency actually went higher (i.e., wrong direction) than the non-enclosed back. I deduced from this that the Khorn bass bin actually benefits from having a little leakage around the top collar between the bass bin and top-hat sections, but there is no benefit from leakage across the tailpiece.

Interesting. EV actually marketed it as a "feature"... interesting.

Chris

notice where the horizontall shelf is in this picture....it's on the floor...no horizontal shelf....in a klipschorn, the horizontal shelf serves to seal into the wall and create a tight fit for a true horn effect. EV's version omits the horizontal shelf and allows mid bass frequency to intnetionally travel higher into the corners providing for a fuller mid bass sound.

[Guest " "]

in a klipsch khorn, the horizontal shelf sits on top of the bass bin

[fini]

Only question: what does BJT stand for? Thanks.

Larry

I was gonna guess bacon, jelly and tomato.

Or __ Time

LOL! Larry, did you by some strange chance see last week's South Park?

[garyrc]

Cask05 (Chris?),

Great post!

Man, are you brave!

Chris, Larry and others: For those amps that have crosover notch distortion, is it true that it is most serious at very low power, e.g., below 1 watt where Klipschorns do much of their work? Does anybody know if my NAD C272 solid state power amp (c. 2005) has crossover notch distortion?

[Chris A]

Man, are you brave!

It's easy when you stand on the shoulders of giants...[]

Remember the [bs] buttons?

Chris

[LarryC]

LOL! Larry, did you by some strange chance see last week's South Park?

Nah, I stay away from smutty shows.

Jon Stewart wraps up my TV evening except for Pawn Stars.

[LarryC]

Chris, Larry and others: For those amps that have crosover notch distortion, is it true that it is most serious at very low power, e.g., below 1 watt where Klipschorns do much of their work? Does anybody know if my NAD C272 solid state power amp (c. 2005) has crossover notch distortion?

That's what I read a long time ago. My recollection is that very high-power amps like the Phase Linear 700 and 400 had higher distortion at very low power outputs, like through high-efficiency speakers. I know that things sounded much purer and better when I went from a PL 400 to an SAE Mark III CM, whose fully complementary SS topology was supposed to minimize that type of distortion. I couldn't improve on that sound until I went to Class A Mark Levinson ML-2's.

This is only historical and off the main topic, but FYI, Jim Bongiorno went on to found and design Great American Sound and Ampzilla, which kept the key to his SAE design:

"Ampzilla was created by world famous designer, James Bongiorno in 1974. At the time, James was the director of engineering at SAE. Prior to that he had been the director of engineering at Dynaco where he created the renowned Dynaco 400. While at SAE, James conceived the concept of the

full dual differential full complementary amplifier topology

which has since, for the last 27 years, become the defacto world standard road map for virtually all high end power amplifiers made today."

FYI:

http://www.ampzilla2000.com/Amp_History.html

[garyrc]

Remember the buttons?

I had one (c. 1978). I think it came with my set of Audio Papers. It disappeared in the early '80s. Too bad -- I could have used it during that decade.

[Chris A]

Too bad -- I could have used it during that decade.

So, are you saying that it's politically incorrect to use that approach nowadays?

Oh my, I really screwed up if that's the case... [] [:$]

Chris [:|]

[Lightguy]

I built absorbtion panels from the DIY section of ATS acoustics for my theatre room. Transformed it from an echo chamber into a pretty decent space if I say so myself.

http://www.atsacoustics.com/

Their pre-built stuff is pretty cheap though.

[Ski Bum]

Does anybody know if my NAD C272 solid state power amp (c. 2005) has crossover notch distortion?

If it does, they seem to have dealt with it very well. Here are some third party measurements of that amp, and they look pretty good. THD+N is <0.03 even at low (sub 1 watt) output. That should be inaudible.

http://www.soundstagemagazine.com/measurements/nad_c372/

I have a C372, the integrated version of yours. It's a great amp, but kind of vanilla, if that makes sense. I think I like my older NAD even more, but that feeling probably reflects some of my own nostalgic tendencies more than real performance. The older one doesn't sound different in a frequency balance sense but somehow conveys an unusual tension, kind of like riding an ornery horse, which makes it more exciting. Maybe that's because it is several decades old and really could blow up at any moment! [] But, no, Gary, your C272 is a perfectly good amp, so you need not worry about crossover distortion. When I compared each of them to the XA series Pass Labs amp, I wanted to credit the Pass with the lucid midrange that class A amps supposedly excel at (and which SETs also possess, or at least seem to via their trickery), but honestly I wouldn't have made a large bet on hearing the difference. The NAD does just what it's supposed to, without embellishment. When listening to the Pass, not only was I straining to hear a difference, but forced to conclude that whatever hair-splitting differences that may exist did not scale with the rather drastic price jump, both of which got in the way of the music.

I have to give kudos to Cask for the extensive effort of compiling these posts, and apologize for my earlier response. I must have been under the influence of some SET spell at the time to have posted such a knee-jerk reaction. Sorry Cask and fellow Klipsch heads.[:$]

[garyrc]

Too bad -- I could have used it during that decade.

So, are you saying that it's politically incorrect to use that approach nowadays?

Oh my, I really screwed up if that's the case...

Chris

Perfectly fine to use it today. The decade of the '80s provided sooooo
much opportunity, though. The period of just plain lying (the '70s ... 20 watt stereo amplifiers being labeled 60 watts) gave way to apparently serious but largely unverified claims. As I remember, that was the time when the
super cables were starting to be hyped (more or less starting with
Monster), exclusive "Golden Ear" stores were springing up
in which horn speakers were denigrated (but
oddly enough, they had no horn speakers in house for us to compare),
some advocated placing bricks on top of your amplifier, and there was
even one article that claimed that people preferred higher distortion in
their amplifiers (it turned out it may have been a temporary co-variant,
namely that massive amounts of negative feedback used to kill
"traditional" distortion gave rise to an increase in other kinds of
distortion, such as TIM)



Sure, there is just as much, or more, snake oil today (suspending your speaker wire using little tripods) but it was in the '80s that I first sorely missed my [bs] button

[garyrc]

Thanks, Ski Bum. Very interesting.