KHorns/Cornwalls and Room Treatment

[cjr888]

Hello,

I've been reading for forums for the past year or so, but have not been an active participant, so be gentle. I have a handful of questions towards KHorns and Cornwalls that I'll open up seperately.

Background - I have a pair of Cornwalls, but system is currently disassembled while we redo the livingroom ceiling. Previously had been using a heavily modified SACD-1000 -> Audio Consulting Silver Rock Silver-Wired Transformer based Volume Control -> 2A3 Amp -> Cornwalls.

When the system is back up, it will be the same source + two other sources -- (1) PC w/modified RME DIGI96/8 pro audio card, and (2) Same Card -> Scott Nixon TubeDAC w/Cryo 1960 Philips Miniwatt -> AudioZone Transformer Based Volume Control -> Peter Daniel's GainClone -> Cornwalls. Very likely may switch to a pair of 300b monoblocks from a local builder though.

Room is approximately 24x14, give or take. Windows and some doors limit some placement on longwall. Previously was using them on shortwall, pulled out from the front wall a few feet. Planning to try long wall when the room is in order again.

Enough of background, and on to the first question:

I'm used to speaker placement theory and room treatment theory for the average speaker out there, and not for horns and especially corner horns. Used to hearing that corners are bad, and from a treatment perspective, how best to treat corners, seams, and first reflections.

Then comes the KHorns where they are supposed to be in corners, and the Cornwalls which have this as an option, and are meant to be closer to the two walls in the corner. Essentially the opposite of what I know.

Does it defeat speaker placement/design parameters to treat the wall seams and corners then if they are supposed to be there?

My best guess is that its positive to use some minor defraction, but not absorption. Thoughts?

First Reflection Points -- Used to speakers being pulled out several feet, and then being 3-4 feet from sidewalls, with easy identification of first reflections. With speakers in the corner, and a more defined radiation pattern, if the speakers are in the corner, _is_ there a first reflection point on the sidewalls? Or is the goal to have the radiation pattern 'fit' w/corner placement?

If this has been covered in other threads, please direct me. Thanks.

[jdm56]

Most people here who use corner-horns do not treat the room much if any. Or at least, that is my impression without actually doing a poll. - Just from hanging around here for about four years.

I guess that makes me the exception to the rule, because I do use RPG Pro-Foam to flank both k-horns (triple layers). It made a tremendous difference in clarity in my room, which admittedly was very reverberant prior to treatment. (concrete floor with thin, padless carpet) So, I don't know for sure if the improvement comes from killing first reflections from the squawker, or just from absorbing some excess room reverb. I tend to think it's a combination of both.

[cjr888]

Was trying to conceive of even where first reflections would occur with corner placement. I need to check the dispersion characteristics of the Cornwall and KHorn compared to a 90 degree corner angle. Also if truly pointed directly out from the corner, I have to wonder if a first reflection point exists.

One thought I had was that you'd think of first reflection points somewhat backwards -- since you're aiming inward more than usual, you mark the first reflection point for the right speaker on the left wall, and vice versa.

Just as a random example, I was wondering if something like MiniTraps < http://www.realtraps.com/mini_stands.htm > placed in the corners, above a corner horn would be of detriment or benefit. I think this might be a sensitive item -- not wanting to affect horn loading too much, but at the same time not ignoring the issues with room interaction regardless of speaker.

But for example, I could see using bass traps in corners as possibly counterproductive, but again, I'm really not sure...

What I will most likely be considering is products like the RoomPak from EightNerve < http://www.eighthnerve.com/response.html >. I spend a lot of time at AudioCircle and know plenty of people that have used their products to great effect. The thing I like is their philosophy < http://www.eighthnerve.com/methodology.html >, which is pretty much to combine reflection with dampening and diffusion vs. just excessive dampening. From my assumptions, with the Klipsch's, this makes sense to me.

I'll probably end up emailing them about cornerhorns to get their opinion on my questions and send off a room diagram... Any useful information of thoughts I receive I'll post here.

Not having an assembled system lets your mind think of too many options to play with it when you can get it setup again....

[D-MAN]

IMO, its rather more problematic than the "tall and skinny" recommended speaker placements which purposely avoid reflective sufaces as much as possible... Corner horns have a new bag of tricks for you to deal with. They can be a bear to tame in the "wrong" room...

1) In general, the dispersion characteristics of the midrange horn is MUCH wider than "normal" typically 90 degrees or more horizontal. This in itself, when placed in a corner will cause a great deal of reflectivity from the outside walls real close to the upper horn mouth(s). I would first tame that with absorbtion (I use Tube-Trap panels mounted vertically 3 or 4 per side spaced about 6 inches apart for that purpose, but as you remind me, there is a reflective strip in them too, along with the absorbtion, I think). I still regard it as mostly absorbtion. This will tend to clarify the soundstage and tighten imaging. Most of my panels are used on the side walls for that reason.

2) I have a couple of panels behind each speaker (or above, as it were) in the same corner at the top, touching the ceiling) on the front wall (i.e. facing the listening position). I also have one panel on the front wall between the speakers which also seems to "clarify" the apparent "depth" of the reproduced "soundstage".

3) The bass end of things is pretty much determined by the room dimensions and even the materials used in the wall construction. If it sounds overly boomy then some corner bass traps may be used in the BACK corners of the room.

That's the end of my experience with it...

There is a bonus to having corner horns that seems to make it all worthwile: they can do some things that are just plain SCARY good!

Good luck!

DM

[DrWho]

to be honest, you really can't start doing room treatments and all that until you get everything all set up and making noise. getting a room to sound good is more of an art rather than a science...

at the same time though, it never hurts to lay out the possible problems you might encounter so that you have a couple things to choose from when you hear something that sounds "wrong."

as far as the corner placement and 1st reflections...i don't think you're going to have to worry about it as much as you might think. i have found that when a speaker is very close to the wall (like a khorn in the corner) that you end up with an extremely large sound...and more often than not, you don't lose any clarity. also, the first reflection that is supposed to happen no longer sounds like a first reflection (having had speakers further out into the room, i take it you know what this sounds like). in the corner, the "bounce" happens so early that it just makes the speaker seem wider than it really is.

btw, you might want to check out the architectural part of the forum...specifically artto's k-horn room and moon's HT stuff. there's lots of good info in there about room treatments and what they're for and what they do and all that good stuff. there's other threads too, but i can't remember them off the top of my head...just check out anything that's over 2 pages long

[jdm56]

A clarification - I believe that with klipschorns in corners, the first reflection point on the flanking walls is going to be not so much driver radiation, but re-radiation (refraction) from the cabinet edges. My feeling is this is at least part of the reason my RPG foam cleans up the midrange clarity so well. That, and it also absorbs some excess reverb in the room.

[garymd]

I know absolutely nothing about room treatments but I can say that IMO cornwalls sound way better on the long wall. My room is the same size and I have mine about 13 feet apart along the long wall, slightly toed in. The soundstage really opens up with that configuration. Try that first then room treatments if needed.

[DrWho]

regarding refraction...

i've never owned a pair of khorns or even heard a pair, but i've always wondered what is happening as far as refraction the way the speaker is set up...to properly load the bass driver, you need the wall to extend at least 48" (at least that's the number i remember). but that's only "one side" to the "four sides" that normally exist in a horn. in otherwords, there is no boundary above, below, or (where im referring to right now) to the inside. the horn opens up into the wall and on the opposite side, it sees a sharp 135 degree angle on the face (tis a guess) where I'm certain lots of refraction is happening.

all that to say, wouldn't there be something one could do to the face of the khorn to possibly increase it's frequency response? i hate to suggest a "tweak" on a pair of speakers i've never heard, nor would i think PWK never thought about what's happening, but I would think there's something special going on at that sharp corner. the effects of refraction on a wave table and with light at those kind of angles are rather significant, so i'd think something similar would be happening with sound (which coincides with wave theory). what would happen if i stuck a big overstuffed chair in front of the speaker? (of course, making sure that it wasn't too wide to cover up the openings on the sides). i kinda just wish i had a pair so that i could just try a billion things and see how it changed the sound. but at the same time, it'd be nice to hear some technical mumbo jumbo explaining all the physics happening there...but that's something i wouldn't do a good job of coming up with myself, but i think i could obtain a good understanding from reading it. i remember fini once mentioning that he plans to put his turntable directly in front of it, but i would think you'd still be getting vibrations happening (from both refraction and the cabinet resonating).

[D-MAN]

I have read a paper concerning difraction at the boundary edges of horn mouths (midrange and tweets). So here is my current approach to things. It is based on some relaxed research and mostly trial by error for my part...

1) No horn mounting baffle at all ; unless you pad it with acoustical absorbtion material...open "cage" style upper cabinet vs. enclosed hard-wood traditional upper cabinet.

2) Directional aiming of "stand-mounted" horns away from the traditional 45 deg. Klipsch upper cabinet alignment (looks great but it ain't the best for the sound).

3) side wall absorbtion close to the mid and tweet horn mouth(s) to prevent direct reflections of upper frequencies from close proximity to side walls

The bass seems to be less of a problem...

DM

[jdm56]

The room wall completes the flare of the bass horn as long as it extends out flush with the front of the speaker. I think it is somewhat less than 48" required to do that. Then you've got the floor on the bottom, so only the top of the horn is open, and then just for the last few inches.

Although the electrical crossover from the bass driver in the k-horn is at 400hz, I believe the actual acoustic crossover takes place at around 250hz. I think that these frequencies are too low for difraction or refraction to be an issue with the dimensions of the cabinet involved.

The tweeter and squawker do have some difraction/refraction issues though, and it is that re-radiation that absorption placed on the sidewalls adjacent to the speaker seems to help eliminate. But then again, maybe the foam panels I use are just absorbing enough stray room reverb to clean the sound up. Whatever - it works for me!

[artto]

There is this mirror technique thing where you have someone hold a small but reasonably large enough mirror flat against the walls & ceiling while you sit in the listening position. When you can see the speakers reflection in the mirror, the location of the mirror is a candidate for some absorption or diffusion treatment.

Interestingly enough, with Khorns, on the long wall in the room corners (or any other speaker for that matter), you will find that you have to have the mirror considerably back away from the speaker until you can see its reflection.

Ive never liked the way Khorns sound with dead areas of absorption around it. It seems to need a live area around the speaker. Likewise, Ive found that they sound better with more absorption along the rear & rear side walls, especially in the rear corners. Its possible to also install bass traps above& behind the Khorns & still have a live surface if you use something like curved Masonite panels.

The mirror technique supports this perspective since the mirrors must usually (in most properly proportioned rooms) be placed more than halfway back into the room in order for you to see the speakers reflection.

Treating the horizontal ceiling corners with bass trap type absorption also helps

[jdm56]

Artto,

Man, I'd like to see your mirror! I tried that technique with the speakers snug in the corners of the long wall in my 18.5 X 16 ft. room and me seated dead center, about 2' from the rear wall. With this arrangement, the mirror had to be almost right at the speaker for me to see the middle of the baffle. At least on the front wall. The sidewall spot was a bit further out into the room, but not so far but what I could still place all the RPG panels equidistant from the corner and cover the reflection point.

I wonder if you are talking about opposite wall reflection instead of first reflection?

Another variation of this method is to sit at the listening spot with a flashlight. Have your spousal unit or any available dupe to hold a mirror on the walls flanking the speakers. Have them move the mirror until the beam from the flashlight reflects dead center onto the mid-horn.

[wrench_peddler]

I have friends in the car audio business and when they aim speakers in custom built boxes, they use a little laser light to get a perfect aim on the sound. They tape them to carpenter squares or home made jigs so they can find the perfect location for the box fronts. The laser pointers would be perfect for the mirror trick.

[Colin]

I had both; Cornies and classic Klipsch corner Khorns. First, with my walnut-oiled Cornwall 1s, with their B2 crossover, I found that placing them 3 to 4 feet away from the front and side walls made a very big difference in the sound, but then, the 3D illusion of the sonic holograph is the most important thing for my home movie and music reproduction system. The Khorns are so much more sensitive, smoother, wider and more natural sounding than the Cornies than everything sounds better with them, corner location or NOT.

I have also filled my ¾ listening room with 8 MiniTraps (see my EnjoyTheMusic.com review at http://www.enjoythemusic.com/magazine/equipment/0204/realtraps.htm). This also made an appreciable difference for every piece of equipment in the room!

[artto]

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On 3/26/2004 10:12:41 PM James D McCall wrote:

Artto,

Man, I'd like to see your mirror!

I tried that technique with the speakers snug in the corners of the long wall in my 18.5 X 16 ft. room and me seated dead center, about 2' from the rear wall. With this arrangement, the mirror had to be almost right at the speaker for me to see the middle of the baffle. At least on the front wall. The sidewall spot was a bit further out into the room, but not so far but what I could still place all the RPG panels equidistant from the corner and cover the reflection point.

I wonder if you are talking about opposite wall reflection instead of first reflection?

Another variation of this method is to sit at the listening spot with a flashlight. Have your spousal unit or any available dupe to hold a mirror on the walls flanking the speakers. Have them move the mirror until the beam from the flashlight reflects dead center onto the mid-horn.

----------------

My front walls are not flat. They have substantial polycylindrical surfaces. So do the upper portions of the side walls. My room is not nearly as square as yours & is substantially larger so the room proportions apparently don't "see" the first reflections anywhere near the speaker. By the time the speaker's reflection can be seen in the mirror on the side walls the mirror is fairly far back into the room, where there is more absorption & bass traps, etc.