Some of these file sizes are large, so please be patient with the download.

This is the second revision of the room. Later revisions look similar, but differ acoustically. I know some of you have already read a previous post of mine describing the construction of room, but for sake of convenience, I'm re-posting here:

I built an entire room around my Klipschorns in the early 80’s & the room has undergone a number of revisions. You & other readers might benefit from what I did & what I learned from my mistakes. The room has been published in several audio magazines over the years.

First things first. Ideally…….you need a room with the proper proportions to achieve uniform distribution of eigentons (low frequency room modes). The ratio is 1: 1.26: 1.59 (called the “Golden Mean”) (see Klipsch Dope From Hope newsletter Vol9, No1 Feb 1968). It doesn’t have to be exact. And rooms outside of these proportions have been known to sound good. Use the long wall for the “stage”. It makes a dramatic difference & you may even find that you don’t have to “turn-it-up” as loud.

Another “trick” you can use is the Half-Room Principal (Room Dimensions for Optimum Listening and the Half Room Principal, IRE Transactions on Audio, Vol AU-6, No1 Jan-Feb 1958, pp 14-15). For instance, my room is 27’ wide. A 42Hz note has a wavelength of aprox. 27’. So based on the longest dimension of the room, the room will accurately convey the full wavelength of a 42 Hz tone. But based on the Half Room Principal, you can expect a reasonably flat room response down to 21Hz (21Hz=54’ wavelength. 54’/2 (one-half of the wavelength)=27’.

If you take this one step further & use the diagonal dimension (which you can do with K-horns because of their corner placement & 45 degree angle toe in) it works even better. My room has a diagonal dimension of 32’ which ½is one-half of 64’. 64’ puts you at about 17-18Hz. My system has measured down only 9Db below 20Hz with no electronic EQ. Not bad for folded horn-loaded speaker of this size. And in fact, that puts the K-horns at about 95Db/watt below 20Hz. Much better efficiency than any of the “sub-woofers” or so-called “flat” “audiophile” speakers out there.

A dimension you want to avoid is 19’ (or multiples & fractions) thereof as it is the wavelength of 60Hz (electrical hum).

A quiet room is a good room. Avoid exterior windows if you can. In my room, I isolated all plumbing (sump & ejector pump plumbing too) from the frame of the house. The plumbing is also insulated. Same thing with any forced air vents. If you can isolate the room’s ceiling & walls from the structure of the house, do so. I didn’t have the luxury of doing that. Remember that wall mass & no air leaks has more than anything else to do with blocking sound.

In my room, I applied silicon beading to the interior of the outside wall studs. Standard R-19 wall insulation between studs. Over the studs I placed 1/2 inch Celotex http://www.us.bpb-na.com/products.html rigid insulation board. Sealed the joints with silicon beading. Silicon beading over the Celotex where the studs are located. Created a 1” air space by putting 1x2 lath over the studs/Celotex. Repeated this process again. Then applied 5/8” sheet rock (Gypsum wall board). Since my room is only partially below ground, the upper wall exposed to the outside received an additional layer of Celotex with a 2” air space between it & the wall. Similar treatment was done for the ceiling. Ilbruck (maker of Sonex acoustical products http://www.mhtc.net/~lowey ) now makes a product called ProSpec Barriers which I would recommend using between the layers of the wall & ceiling.

I also heavily reinforced the corners for the Klipschorns, from the corner, to 8’ out from the corner. I used a staggered 6-12” stud spacing, both horizontally & vertically to eliminate any wall resonances. I then made 4 “plates” out of 2x12” wood, fit into the studding & secured them & the wall, tightly against the foundation. I made a corner fitting out of 2x12 to fit securely & air tight (use foam weather striping) in the corner for the tail board of the Klipschorns to be secured onto. The corner board is secured to through the wall to the foundation with 10, 1/4 inch lag screws. The tailboard of the K-horns are secured with 8, 1/4 inch lag screws to the corner plate. The K-horns are sealed air tight into the corner with weather stripping foam.

In regards to electric, have everything on its own circuit. I’m not sure that 20 amps is enough nowadays. Obviously this depends on what kind & how much equipment you have. Tape decks for instance can draw a lot of current because of the motors in them. Make sure you use an isolated ground for that circuit, isolated from the rest of the electric in you home. Ground the system at only one point, preferably from a regulated power supply that everything else is plugged into. Float all the rest of the ground connections on your equipment using a 2-prong adapter so that the ground(s) “seeks their own level” & does not produce any ground-loop hum. If you are using light dimmers, make sure they are the kind that have RF filtering. No fluorescent lighting.

Now for acoustics. The Klipschorns do not like “dead” areas around them, so forget that “dead-end/live-end” room stuff. It doesn’t work with K-horns. I use large polycylindrical surfaces made from 1/4 inch tempered Masonite (a wood-based fiber hardboard) (cheap) bowed to 12” on larger ones (4’x8’), 6-9 inches on smaller ones. These can be painted to match room décor. Behind the cylinders I mount Sonex acoustical foam on 3-6” standoffs on the Celotex behind the Masonite so the Sonex can capture sound more effectively from all directions & angles. This produces a room with very well distributed/dispersed middle & high frequencies. The larger polycylindrical surfaces help to damp bass resonances & break up standing waves. The principal here is to allow the room to be relatively “live” at low volume levels. But as the sound levels increase, more & more reflected sound gets trapped behind the cylindrical Masonite panels & gets totally absorbed by the Sonex & Celotex behind it so the room does not acoustically overload due to increased reverberation time at higher volume levels. A simple thing such as clapping your hands can be very useful in locating “hot spots” or ping in various areas of the room which will require sound absorption or dispersion. Likewise you don’t want any dead spots either. These Masonite panels can create quite a dramatic appearance, so be creative & experiment. Keep in mind that the bow in the Masonite panels will tend to “push the walls of the room in” making the room seem somewhat smaller. This can be overcome by the use of lighting to highlight the depth & curve of the panels.

The carpet flooring you see in this picture is composed of large sections of rug remnants. This allowed me to experiment with their affect on the room's acoustics. Later it was decided that very heavy weight carpeting & padding wall to wall would be best.

These are the equipment racks. I designed & built them myself. This photo is from a long time ago. The racks are now completely crammed with gear. They were designed to provide ventilation & convenience in changing components. I used slotted wall-mount-type shelf standards & brackets on both sides of the racks to hold the shelves. The turntable stands were weighed down with more than 300 pounds of solid concrete blocks "floated" on closed cell foam.

This is how the room currently looks. Notice the change in size & direction of the polycylindrical diffusers/dampers.

Sorry about the width of the picture being cut-off. I need to rent a 20mm wide angle architectural lens in order to get the whole thing in.

All of the Sonex foam & Celotex tiles are now behind the Masonite diffusers. This lets the room remain somewhat "live" at low volume levels. As the sound levels get louder, more & more sound gets trapped behind the diffusers. The result is a room that has similar reverberation time at low or high volume levels. It basically prevents the room from getting acoustically overloaded. The large Masonite diffusors are also helpful in damping the bass frequencies & breaking up standing waves.

A closer shot of the acoustic diffusers/dampers

Diffuser/Damper detail closeup

Very cool. Talk about taking something the nth degree.

I've been following that 'other' thread, and based on what I'm seeing here, there can be no question that you can easily duplicate the large scale dynamics, timing cues, and the proper relationship of direct and reflected sound -- necessary to recreate the "live" music experience.

I can't help but wonder however, if it isn't just the sheer amount of acoustic space you have provided -- that contributes more to this effect than anything.

None-the-less, very impressive.

I especially appreciated the commentary, and the math behind some of it. I have several questions, but need some time to digest some of things you've said.

I've always enjoyed the near field experience, but I listen to mostly Rock music. My main listening area is the bedroom, which is on the 2nd floor of a cape cod type house. The bedroom covers the entire 2nd floor, and though rather long (about 20 feet) -- the speakers are on the short wall at one of the ends, and I sit about 8 feet back -- with all the wide open space behind me.

So, If the room is 20 feet long and 12 feet wide -- what does the math say should be the optimum distance from the rear and side walls?

I'm also curious about the bass. If you have the acoustic space necessary to propagate the wave properly -- but you are only sitting 8 feet away -- do you still "hear" it?

Thanks,

Dean, I’m not sure if you are referring to speaker placement in relationship to the wall boundaries, or the overall proportions of the room. The calculations I’m referring to have to do with room proportions & distribution of eigentons (low frequency modes).

From your description of the room, I have several questions. Does your room have a vaulted ceiling? Is it angled just from one side as a shed roof or is it more like a gable roof (angled symmetrically in 2 directions)? Or is it a flat conventional ceiling?

The more non-parallel room surfaces you have, the better, unless they are forming a concave sort of interior. In that case the angles may cause an effect similar to that of concave curved surfaces which will tend to focus the sound into hot spots.

The more non-parallel wall surfaces, the better the mode distribution of the room, & the more complex the resonances & their calculations become.

Just for the record, if I assume for the moment that your room is rectangular with a flat standard ceiling height of 8’, the room size of 20’x12’ is well outside the desirable proportion ratios of 1: 1.26: 1.59. Under these conditions the room should exhibit excessive bass response at 141Hz. There are 3 occurrences at this frequency (bad). The 2 worst ones are caused by the room’s length to width ratio and have rather high values (bad even if you have a vaulted ceiling). Interestingly, your listening distance of 8’ is also the wavelength of 141 Hz (you really, really like that 141Hz frequency, don’t you! Just kidding).

I’m not familiar with the RF7, but from what you describe as your listening position, it appears that the geometry between the speakers & the listening position indicate that the speakers are placed in the corner & toed-in about 45 degrees. I’ve found that using the long wall for speaker placement (as PWK recommended) results in a much more believable “stage”. The problem with your room is that if you put the speakers on the 20’ wall, you really don’t have enough depth. You will be backed up against the rear wall. The bass frequencies tend pile up there, and the room already has a huge bass hump.

As an alternative, you might consider (ironically) making the room smaller, 12’x15’ produces better eigenton distribution with a fewer number of mode resonances. You might use the smaller leftover space to get your equipment out of sight behind the speakers, and for storing recordings, etc. Or you might construct some large panels or moveable wall partitions so you can experiment with breaking up the standing wave/resonance problems.

You might be interested to know that in my room’s original incarnation I had the speakers on the shorter wall & had lots more room depth behind me, “theater style”. While that may work in larger the sized spaces of theater/concert hall sizes, it doesn’t seem to be the choice for optimum audio performance in domestic environments. I know that goes against conventional thinking (but hey, who ever said PWK was conventional?), especially with home theater setups where people tend to want that long room dimension for “theater-like seating”.

I was quite surprised at how the sound opened up in terms of sonic breath & depth & detail (and at seemingly lower volume levels) when I put the speakers on the long wall. On the other hand, my room has enough depth, even with the speakers on the long wall, for the listener to not be backed up against the back wall.

Regarding the bass propagation question, I’m don’t think that really applies here. You can produce deep bass in pretty much any room, or even without a room (ie: headphones). This is more about how many room modes there are & their distribution & their overlap (where one resonance can reinforce another). The RF7 is a much smaller speaker than the Klipschorn & is not designed with stringent corner placement requirements as an absolute must. K-horns need some room to breathe & a listening distance of 8 feet is a little less than the minimum desirable distance IMO. I’ve had the K-horns in rooms like that. And there is absolutely no comparison to what they are capable of in a proper room. And if you’re using a large center speaker, the center speaker is even closer to you and it gets difficult to blend the sound from all the speakers into a “continuous curtain of sound”.

Music room hell,, HALL, wish i had the room, for something like that!
Jim

Dean, I forgot to address your comment regarding “the shear amount of space you have provided – that contributes more to this effect than anything.”

It’s true. But it would be nothing without the proper structural & acoustical treatments. In fact its not only the size of the space, but also the lighting that makes the room seem more spacious & dramatic. Years ago I noticed that highlighting the front walls with high contrast spot lighting on “clean walls” seemed to add to the 3 dimensional effect in audio. It seems to give added dimension to the illusion of space. I guess it might fall under the category of psychoacoustics . On the other hand, while the room has generous proportions, don’t forget that the wide angle camera lens required to photograph the space is also distorting the appearance of the room’s size. Its not quite as large as it looks.

And Jim, you got it! That was kind of the whole idea. To make it look & feel like a concert hall.

System/Room Frequency Response.

The measurements were taken from the listening position using a McIntosh Real Time Analyzer & calibrated B&K microphone I borrowed from a local dealer. This graph is from the room as shown in the first photo in this post thread. It was taken in 1982. The source test signals used were from the Crown Test Equalization Record (vinyl LP). Playback was performed on a Linn Sondek LP12 turntable, Decca International pickup arm & Decca Maroon phono pickup. Amplification used Audio Research SP6A preamp & Luxman MB3045 triode monoblock power amps.

The bass hump at 160Hz is due to the Decca pickup/pickup arm. I suspect the rapid fall-off of frequency response at 16KHz is also due to the Decca Maroon pickup which uses a spherical (conical) stylus. In recent years, I’ve decided that the room was “over-stuffed” with sound absorption materials in the rear of the room and this may also have contributed to the high frequency roll-off. This is one of the reasons for the new acoustical treatments seen in the more recent photos. The 160Hz hump doesn’t seem to be audible when using the Decca Maroon in an SME III pickup arm using the medium size damping paddle. The other phono pickup I currently use is a Shure V15 type VxMR which provides much smoother and more extended response. After I complete the current acoustical & architectural revisions I’ll re-run the tests both from vinyl & CD.

Remarkably flat freq. response.

Here is mine, with a Stereophile test CD for test tones and a rat shack SPL meter, corrected for rat shack non-linearities:



I would like to know if you are taking the picture from the listening postion or the rear wall. It almost seems like the rear wall, except for the lack of furniture.

Also the Belle is interesting. I heard a Belle for the first time a while back and was, to be frank, not impressed. I would not have one in my center channel.

Randy,

I think you'll need to hear the Belles in a much better venue again, before passing judgement on them. I had them hooked up to a $200 10 year old CD Player, with a SS Pre-amp and most importantly in a poor acoustic friendly room.

When I get these Finished and placed in my main room, with Tube DAC and my Fet-Valve Pre-amp, I think you will like them more. I also have the 300B meshplate tubes now. Who Knows what a different crossover will do. Anyway I do think that they have potential.

Kevin,
I agree completely. I am a big believer in how ruthlessly revealing these horns can be. What comes out is what goes in, for the most part.

I guess if I built a room around khorns, I would have used a third with false corners for center, as was the rage a decade or two ago.

This forum is AWESOME for Klipschorn advice.
ARTTO... I have a room that is 16 X 26, and I am just setting up my system. I had been planning on setting up my Klipschorns in the corniers of the 16' wall. My other 16" wall is actually a railing overlooking my stairs going down to the first floor effectively making the room another 4' long if that makes sense. Hence 16'X 30' My ceiling is 8' with another 1' Making it 9' in the center (coffin ceiling) which is about 8' in diameter. My question is... Is my placement of the Klipschorns idea and does the staircase at the other end of the room help or hurt me? Thanks and all the best, Guy

Guy, unfortunately Klipschorns are not for every room or environment, at least not in terms of achieving optimum performance. That’s why Klipsch made similar speakers with near equal performance that did not have the mandatory 45 degree angle & corner placement.

In your room, it seems to me, that the open area on the one side of the which leads downstairs may cause a somewhat lopsided sound, at least in terms of the overall sense of acoustic space (reverberation & reflections of sound).

You would definitely have to build a false corner or replace the railing with a wall to use the long wall for the Khorns. No, its not the “optimum” thing to do. But hey, Paul Klipsch used false corners in his second house.

The other problem you have is the room proportions. 16’x26’ should be fine, but 16x30 starts to get excessively long which may make the system sound bloated at certain bass frequencies.

You may want to build false corners for both horns & secure them to the house walls. You could even make them much taller than the Khorns (to cover up that open/railing side of the room). Just make sure the false corners extending above & beyond the Khorns are not vibrating too much as they (just as weak walls can) act as passive radiators affecting the bass response. Making the false corners extend more than 4’ from the corner will yield negligible improvement.

The long wall is the most desirable to achieve a wide-stage stereo perspective which gives the largest “good” listening area. However, there seems to always be that “sweet-spot”. It also allows one to perceive the proper “scale” of larger music productions such as symphony orchestra. However, many recordings are mixed with far right & far left perspective in mind to sound more “stereo” on most run-of-the-mill playback systems. This is one of the reasons for using a third, derived center channel. I’ve also found that use of an “audio imaging control” or “panorama” stereo to mono blend control as some preamps/control centers have is useful to bring the stereo image in from the far left & right sides. It just helps to dial the image in to a more realistic scale & perspective if the recording was not mixed optimally for playback on larger systems.

I originally designed & built my room to accommodate the Khorns on the shorter (18.5’) wall so I would have more room depth for ambience, as in a concert hall. The curious thing I noticed when I experimented moving the Khorns from the 18.5’ wall to the 27’ wall was how much the sound opened up. It now seemed as though you were “in-the-space” with the orchestra, and the perspective was large enough to sound like a real live band was in front of you on things like rock, pop & jazz. And I didn’t feel a need to turn the volume up as high to achieve the same impact. Needless to say, I had to open up the other room corner and walls, & reinforce it like the other side.