Need advice; can't raise ceiling much

[garyrc]

In redoing our music room, I just found out it may be too expensive to raise the 7' 8" too-low ceiling (due to needing to remove the roof in that section of the house, extend the walls upward, with the idiosyncratic foundation not being able to handle the additional weight without re-pouring it somehow, etc.) We are casting about in desperation for a solution, because the Khorns, which we love, don't sound nearly as good as in our old house with a ceiling that sloped from about 9 to 14 feet, but with other proportions that were less favorable than in the current room. The main loss is in 1) The "airy" free floating nature of the sound, and 2) imaging. We still might be able to raise the ceiling a small amount without adding much weight, and without taking off the roof.

If all else fails, I'd like your opinions on some options to partially counteract the effect of the too-low ceiling:

• Move the Klipschorn tweeter back, and put absorption at the ceiling's first reflection points. In Heyser's old Audio review, he said that the Khorn sounds better with a high ceiling (Klipsch now recommends > 8.5 feet), because the out of phase and closer tweeter sound can bounce off a low ceiling and arrive at the listener's ears before some of the rest of the sound gets there (or, I guess, in relation to the midrange, the reflection arrives too soon after the initial sound gets there). It used to be commonplace to take the tweeter out of the Klipschorn and place it on top of the cabinet, with its diaphragm lined up with the diaphragm of the midrange driver, to put those two in phase, and make the treble and midrange arrive at the same time. Does anyone still do that? How does it sound? How do you keep the treble from reflecting off of the top of the cabinet? I'm considering front mounting the tweeter in its own box, and covering the top surface of the Khorn cabinet with velour, felt, velvet or something, to reduce reflection. I'm also considering raising the tweeter about 6" or more and aiming it very slightly down at the listeners (hoping that the velour will minimize any increased reflection), and rotating it so the ears of the person in the center seat are directly on its axis. That would have the tweeter and the mid horn aimed differently in two planes, and I'm not sure of the effect of that. Would the 6" or more elevation of the tweeter separate the midrange and tweeter sound too much? To get rid of the visual cue, the two corners & Khorns could have an acoustically transparent fabric in front of them (the same as on the nearby walls), with the Khorn's own grille cloth taken off. A pity, because as I said only yesterday, we like the look of the Khorns.

• Or, we could get rid of the top hat almost completely, just securing the baffle / motor board to the top of the bass bin (the mid horn needs the flange/motorboard interface, according to an article in Klipsch's Audio Papers) then put the tweeter in it's own box with diaphragm aligned with the mid driver, and elevate and aim it as described above. That way, there would be no large flat surface nearby to produce a gross reflection; the K401 mid horn could have velour draped over the top of it (not the mouth!), and the velour could be tucked in and cover the rest of the top surface of the bass bin. We would still put some absorption on the first reflection points on the ceiling.

• Or, probably for less $$$ than raising the ceiling would have cost, we could buy some kind of delay, to make both the direct sound from the tweeter and midrange, and their respective reflections arrive at the same time, although I hate to add one more piece of electronics to the signal path.

Any suggestions?

Thanks,

Gary

[JJkizak]

What would be the cost of lowering the floor?

JJK

[artto]

Gary, you need to try and make the ceiling acoustically disappear. Try using something like these RPG Skyline diffusors.

http://www.rpginc.com/products/skyline/index.htm

They're expensive but far less expensive than raising the ceiling!

The other thing to consider is that "ILLUSION" can go a long way. Most people who come over to my place for the first time comment on how nice it must be to have a nice high ceiling on the lower level. To which I tell them "it's not quite eight feet". The taller ones reach up and to their amazement touch the ceiling.

Lighting and Illusion can go a long way making your think its more spacious than what it is.

[Pete H]

I'm in the process of raising the ceiling in my home and sometimes it's not as difficult as it may seem. What is the general roof construction in that area of the home? Pitch, run, truss or stick frame?

[Don Richard]

It used to be commonplace to take the tweeter out of the Klipschorn and place it on top of the cabinet, with its diaphragm lined up with the diaphragm of the midrange driver, to put those two in phase, and make the treble and midrange arrive at the same time. Does anyone still do that? How does it sound? How do you keep the treble from reflecting off of the top of the cabinet?

I believe Marvel has done that with his Lascalas, but I'm not sure that is the answer to your problem. You are probably getting ceiling bounce, floor bounce, and wall reflections. Sit at your listening position and have someone take a mirror and slide it along the walls, the floor and the ceiling (get one of your tall friends for that). If you can see the tweeter in the mirror at any point, those locations are where absorption will need to be placed. Sonex panels, egg cartons, heavy carpet, or drapery are all good absorbers of unwanted HF energy.

[wuzzzer]

[Marvel]

It used to be commonplace to take the tweeter out of the Klipschorn and place it on top of the cabinet, with its diaphragm lined up with the diaphragm of the midrange driver, to put those two in phase, and make the treble and midrange arrive at the same time. Does anyone still do that? How does it sound? How do you keep the treble from reflecting off of the top of the cabinet?

I believe Marvel has done that with his Lascalas, but I'm not sure that is the answer to your problem. You are probably getting ceiling bounce, floor bounce, and wall reflections. Sit at your listening position and have someone take a mirror and slide it along the walls, the floor and the ceiling (get one of your tall friends for that). If you can see the tweeter in the mirror at any point, those locations are where absorption will need to be placed. Sonex panels, egg cartons, heavy carpet, or drapery are all good absorbers of unwanted HF energy.

I probably get some bounce, too, but I am also probably ignoring it. [:^)] For a while I placed some absorptive material on the top of the LS cabinets, in front of the tweeters (Eminence APT150), but I really couldn't tell the difference with or without the material in place. The sound seemed more precise, though, with the drivers aligned. My ears are also slightly lower than the tops when I am sitting on my couch, which could explain my not hearing the reflections.

[garyrc]

I see that your Eminence tweeters are elevated a few inches above the top of the LS. I was considering doing that (with Khorns), because I could then point them down a very few degrees to aim them at listeners on a couch.. Could you answer a few more questions?

• Do you get any sense that they are "disconnected" from the main sound of the LaScalas with that much separation?
• How many inches above the LS top is the center of the tweeter?
• How would you describe the difference between the Eminence sound and the sound of the K-77 you removed?
• What crossover are you using?

Thanks!

[Marvel]

Do you get any sense that they are "disconnected" from the main sound of the LaScalas with that much separation?

Not at all. The sound seems very full and cohesive. Perhaps due to the 100x50 dispersion pattern of the horn.

How many inches above the LS top is the center of the tweeter?

The center of the horn is 7.75 inches above the tops of the LS. I made an arbitrary decision to make the baffles 12x12, and placed the horn at the top of the baffle with an equal distance top and sides (not sure if that makes sense...) The 12x12 sits on a 3/4 inch base.

How would you describe the difference between the
Eminence sound and the sound of the K-77 you removed?

I had already swapped out the K-77 for Bor Bob's CT125s. Since the actual driver is the same, I will say the sound is similar but larger. I find the Eminence driver to be very smooth sounding, and not nearly as harsh as the K-77.

What crossover are you using?

I am using the DHA2, from John Albright. My LS came to me with the AL series, which I found to be very harsh (to my ears). I did drop the mids down a notch on the autoformer, and the balance sounds good to me (and to others who have been able to hear the system).

I am using SET amps to power them (Moondog 2A3), with a Juicy Music Merlin front end. My CD player is an old single disc JVC, almost 20 years old.

Bruce

[garyrc]

SEE a few posts ahead .... ONE picture finally got transferred

Hi Pete H,

Originally, we wanted to just have the roof taken off and thrown away, and a higher & sloped ceiling/roof put in, front to back. We still may do some version of that, but it looks like it would be too expensive (about $88K to $114K estimated range by two contractors for changing out 4 windows, making sure the foundation is firm enough, taking off roof, making walls higher, and putting in sloping roof / ceiling.

The compromise would be just to use the existing space in the attic to raise the ceiling a bit, with the ceiling parallel to the existing roof, following its lines, and changing how it is held up, without removing it.

Here are some pictures of the two parts of the attic that are above the room where we will have our sound system. I hope these pictures come through ... if not, can anyone refresh my memory on how to post pictures on the forum? The front half (under the end of the room where the speakers must be) has an A frame roof as seen in picture 1. The rear half slopes down to it, as you see. At the transition point, there may be an "I" beam or something buried in the insulation that we would like to get rid of.

At the rear, there are some funky braces like the one you see here.

[Chris A]

It may be a lot cheaper to buy a couple of K402's with K69s, which will crossover to the Khorn bins at 450 Hz - the point where they crossover to the midrange now. The K402s could replace your Khorn top-hats (i.e., the tweeters and midranges), and will solve the ceiling bounce problems by solving the problem at its source.

There are both passive and active (i.e., bi-amping) crossover solutions available to integrate with the Khorn bass bins. If you go active, then you can correct for the ~7 millisecond delay between the bass bin and the upper drivers (and between the tweeter and midrange) without having to mount the tweeter in a difference place on top of the unit.

You'll also like the audio performance.

Chris

[garyrc]

• "It may be a lot cheaper to buy a couple of K402's with K69s, which will crossover to the Khorn bins at 450 Hz - the point where they cross over to the midrange now. The K402s could replace your Khorn top-hats (i.e., the tweeters and midranges), and will solve the ceiling bounce problems by solving the problem at its source.'

Chris, the K402s are the big horns on top of the Jubs, right? I'm not familiar with the K69s ... are they passive networks? Or are they the super tweeters that go on the Cinema Jubs that are sometimes called something "Grand" something? Don't they seem to be offset ( and therefore as out of phase) just about as much as the k-77s in the Khorns?

• Can somebody help me figure out how to post the pictures I took with my digital camera of our attic, so I can answer Pete H's question by showing him pictures? I have AOL.

[garyrc]

ONE picture got on, below.

"What is the general roof construction in that area of the home? Pitch, run, truss or stick frame? "

Hi Pete H,

Well, I have pictures of the two kinds of construction that are in the attic above the room, but I can;t seem to get them on to the forum. I'm not familiar with "run" ... my best guess is that the front part of the attic, over where the speakers are is "sitck frame" with posts going up from the center line of the ceiling straight up to the ridge board. The roof has a shallow "A" shape in that area..... the rear part slants up from there to the middle ridge of the house, which runs perpendicular to the ridge mentioned earlier.

Originally, we wanted to just have the roof taken off and thrown away, and a higher & sloped ceiling/roof put in, front to back. We still may do some version of that, but it looks like it would be too expensive (about $88K to $114K estimated range by two contractors for changing out 4 windows, making sure the foundation is firm enough, taking off roof, making walls higher, and putting in sloping roof / ceiling).

The compromise would be just to use the existing space in the attic to raise the ceiling a bit, with the ceiling parallel to the existing roof, following its lines, and changing how the roof is held up, without removing it.

If I ever figure out how to post pics from my digital camera onto the forum, I will. The pictures appear just fine in the "Message" window on the forum, but fail to transfer onto the forum itself, leaving only text.

[WMcD]

I'm going to be a bit of a doubting Thomas here. But I do want to support your project.

Taken that you do have an acoustic issue, it seems to me questionable that raising the ceiling by 10 percent is going to change much.

I recall that Klipsch in recent days has suggested a higher ceiling. My thought is that this alters bass reinforcement, to pick up some bass gain lower freqs.

I don't doubt that a given room can sound better for imaging and reveberation. That is, as you suggest, a matter of acoustic treatment -- and not limited to the ceiling.

I hesitate to question Artto or the RPG people. None the less, I don't see how the Skyline panels work. There ARE panels with wells (holes) which are of a specified depths in the RPG theory. The sound goes down and back and thus the reflection from the panel has a specific delay at various spots to make a phased array of delayed reflections, and this causes dispursion / defraction.

Yet in the Skyline, we have no wells and thus no scentifically calculated delay. They may do some good in that the sides of the stalactites or skyline of buildings form absorptive surfaces. It is a lot of money for these and I'd think that some less exotic and less expensive treatment would do as well.

Wm McD

[DrWho]

Gary, have you considered a phase grating between your room and the attic above? A true phase grating is more than this, but it's essentially "vent holes" that couple your room's space with the space above. You could easily get a pattern that fits between your ceiling joists and effectively get the full benefit of the height of the attic in addition to some other benefits that phase grates provide (when properly implemented).

I guess the biggest downside would be the thermal efficiency issues of having your room's air coupled with that of the attic, but maybe that could be taken care of above the phase grating...

Btw, RPG Skyline Diffusors are awesome....definitely pricey, but they work real well. I guess I don't understand the confusion about how they work? You really need to have multiples of them on the ceiling to make them effective.

[garyrc]

William F. Gil McDermott : Taken that you do have an acoustic issue, it seems to me questionable that raising the ceiling by 10 percent is going to change much.

Thanks for the support and help you've given over the years.

My reasons for thinking (hoping) it might make a difference are:

• It would be somewhat more than 10%, but it isn't the percentage that makes me think it would work, [woops ... see Dr. Who's post, ahead]but Jeff Cooper's contention that delaying sound by 35 milliseconds makes the brain think that the sound is a separate event, that gets chalked up to reverberation/echo, rather than the original sound. A 35 millisecond extra delay of the ceiling reflection could be achieved by adding 48 inches, unless I've miscalculated .... so adding 2 feet extra distance to the journey of the sound from the tweeter on the way up to the ceiling, and 2 feet more down to a listener's ears might make the reflection seem more like "room" than "source," and that extra 35 milliseconds it might cause the tweeter reflection to be separated enough from the primary sound of the midrange to alleviate the problem Heyser referred to, and that caused him to recommend high ceilings & thick rugs for Khorns. By the way, we have a thick rug, and the side wall first reflection points will be diffusing. If the ceiling can be made even higher, we will probably have room for some diffusers at the ceiling's first reflection points.
• The fact that the Khorns sounded so much better in our house in Oakland, with it's high ceiling, than they do here, with a 7' 8" ceiling. The length of time between the last time we heard them in Oakland and when we set them up and heard them in our Oregon house was about 5 days.
• I once made a party mix (from tapes) in a room with a low ceiling, heard it in there, then moved it into a room with a high ceiling (and a bigger room in general, granted) and heard it about an hour later. My friends and I were overwhelmed by how much better the big room sounded.

What do you think of the Russ Berger Space Arrays, or what ever they are called? I mean the 2 foot square wooden diffusers that have 64 boxes in them, filled to various depths. There is one that Auralex has, and someone else has one that looks like the pattern of filling the boxes is different. They look better than the Skyline cityscape varieties.

[DrWho]

A 35 millisecond extra delay of the ceiling reflection could be achieved by adding 48 inches, unless I've miscalculated

Sounds travels at 1132 ft/s which is roughly 1 ft/ms. To get an extra 35ms of delay requires increasing the pathlength by 35ft. Adding a foot to the ceiling will only buy about 2ms...

What do you think of the Russ Berger Space Arrays

I'm not Gil, but when properly implemented they work quite well. On the Auralex site, the "Space Coupler" is similar to the phase grate concept I mentioned. If you wanted to be creative, you could combine a "space array" and "space coupler" into a single product.

That said, the space array requires quite a bit of distance between the listening and the reflection point in order for it to properly diffuse. You usually seem them employed on back walls as shown in the pictures on the Auralex website. That's not to say that they can't work on a ceiling, but they probably won't work with a ceiling that is too short.

[garyrc]

Thanks, Mike. I had a decimal point problem.

Do you know of a kind of diffuser that works well some 7 to 9 feet from the listener's ears?

[Chris A]

Chris, the K402s are the big horns on top of the Jubs, right?

Yes - these horns are able to control their patterns all the way down to the 450 Hz crossover frequencies, thus controlling the bounce off the ceiling.

I'm not familiar with the K69s ...

These are the drivers that would be recommended for the K402 horns.

Chris

[Marvel]

Gary,

The Klipsch K-69 driver is the same as the P-Audio BMD-750. You can look it up on their web site or at

http://www.usspeaker.com