Make a homemade Legend center?

[redtop]

Alright dang it...now I'm confused (anybody suprised?[])

Rob,

Can you describe what you mean by increased vertical dispersion?

Are you referring to a condition caused by the horizontal

orientation? Or the increased distance between my woofers?

Do you agree with DrWho about a "vertical" orientation for the center

being sonically optimum?

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

Just for the fun of it I'm considering building a "test" cabinet with

KLF-30 dimensions from 3/4" MDF as a test unit. That way all I

have to do is take the drivers out of the my current center and use

them with various motor board configurations. If I don't like it,

I can easily go back to what I have now. I'm considering testing

the following configurations based upon ideas presented in this

thread...

#1 - a motor board with horns in the middle, woofers on each side, but

with woofers as close to the horns as possible without losing

structural integrity of the motor board...a la HornEd. The

configuration would have the classic center channel horizontal

orientation with ports moved to the front and positioned at the far

left and right of the motor board.

#2 - a motor board with horns and positioned as in #1, BUT change the horns 90 degrees to offer a vertical orientation as suggested by DrWho in a prior post.

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

Ok Billy, I know, I know...this is now officially a plane on it's way

to Cuba...[] I just hope you gain from this information as you

consider your custom center.

Thanks.

[wstrickland1]

in the immortal words of, umm, that dude that overtook Bahboo and company and crashed the plane headed for the White House...........LET'S ROLL!!!!!!!!!

Actually, that last post turned the plane back towards Cincinatti. Now is Who saying the horns should be positioned like a stock speaker when laying down and not how yours is, like the C7 is I guess? That does make you wonder why they did the C7 like that. MAybe WHo knows what he's talking about.

And lest I forget, hey Doc, is Cindy Lou your little sister?

Billy

[rich0372]

Just for the fun of it I'm considering building a "test" cabinet with KLF-30 dimensions from 3/4" MDF as a test unit. That way all I have to do is take the drivers out of the my current center and use them with various motor board configurations. If I don't like it, I can easily go back to what I have now. I'm considering testing the following configurations based upon ideas presented in this thread...

redtop this is a good idea you can still get lengend speaker parts from Klipsch Building your own center out of mdf to the exact dimentions of a klf 30 might be more cost effective than buying one used and modifing it [] what a great idea Rich

[wstrickland1]

I think Red already has the drivers, but I can tell you that 2 woofers, midrange and horn, tweeter and stock crossovers are $440 shipped. That was for KLF 20 woofers, so the 30s might be a little more. Also, Klipsch told me that I got the VERY LAST K 703 horn available. Something to think about if starting from scratch like I did.

Billy

[redtop]

Rich,

I am planning on using the drivers from my existing center for

testing. I'm passionate about this project, but not so committed

as to get an extra set for true A/B testing...[]

Billy,

Good point about the C7 horn. I had totally forgotten that it is

rotated 90 degrees out of axis for the "normal" horn orientation.

I look forward to some more input from the good DrWho and Formica.

Brad

[DrWho]

The increased vertical dispersion is a comparison against the stock KLF-30 alignment. The vertical woofer alignment of the floorstanders reduces vertical dispersion and maintains the natural dispersion of the drivers in the horizontal plane. When the woofers are converted to a horizontal alignment, you now have the normal dispersion occuring in the vertical plane and a narrowed dispersion in the horizontal.

Which setup is better is going to be a function of your room's acoustics...though I would favor an identical alignment to that of your mains because the floor and cieling reflections will then be identical - thus maintaining a perfect timbre match (the acoustics of the room have a huge impact on the timbre of the speaker). Also, a vertical woofer alignment increases the horizontal dispersion which allows for a wider seating arrangement...In most typical home setups, you might have people sitting rather close to the mains, who won't be able to hear dialog very well if they don't fall into the dispersion pattern.

Did I mention using a "vertical" alignment for the horns? I don't remember doing that [] In fact, I don't know what I'd suggest because I can see two lines of logic:

1) Orient the HF section identical to that of your mains regardless of woofer alignment

2) Orient the HF section relative to the woofer alignment (so if you go with a vertical alignment, then orient identical to the mains. If you go with a horizontal alignment, rotate the tweeter 90 degrees).

Both methods have advantages and disadvantages which I think are kinda obvious though I can elaborate if needed. This is really where the compromise is going to come into play.

I don't currently own the fancy software needed to model your situation or enough speaker information, but this is something that can definetly be modelled and an optimum situation obtained for your room...or you can just build the cabinet so that the HF section is rotatable and decide on the best solution experimentally.

Btw, don't build two different cabinets...just build two different motorboards and design the speaker such that you can easily swap between them. If this is already what you had in mind then consider this a confirmation of your approach [] You can even build both baffles such that the HF section is rotatable inside the motorboards. I can give you some rough plans if you give me some dimensions, but I think you can figure it out. (Just mount the HF section to its own square motorboard which would then screw into each of the larger woofer motorboards). If you want to be real fancy, you could mount every driver (horn, woofer, woofer) to the same sized square boards (3 boards total) which would then allow you to interchange between any number of alignments. If you're real clever I can think of a few ways this can be done and still have a finished look. Am I overengineering this enough yet? Cuz I've still got a few more ideas []

Btw, is this getting confusing enough yet with all the relative reference points? lol. I think I got everything straight.

One other design tip...the screws for the woofers and the horns are probably going to be very close together. You might consider doubling up on the thickness of the motorboard in these sections (basically cutout a big rectangle just larger than the openings and then hollow out the middle to be the same size of the openings...giving you a 1" frame which the screws will drill into). In fact, if you're going to be doing a lot of switching around then I would highly recommend going with T-Nuts because you'll never have to worry about stripping the wood (which is very easy to do)...when installing T-Nuts, be sure to use screws that are extra long for setting the nuts...put the bolt through and then attach the T-Nut while it's all still loose...then tighten the screw and guide the T-Nut into place. Don't be an idiot like me and pound in the T-Nuts with a hammer because you can never get them aligned straight and you'll end up throwing your cabinet in front of a semi-truck on the highway []

[formica]

I agree there is no "right or wrong" way of treating dispersion, both in the horizontal or vertical plane... just different compromises. Unfortunately my knowledge in this is somewhat limited, so I can only present my understanding.

My reasoning comes from that, in general, you'd like the centre channel to act more as a point source for the voices while the left and right channels to add the ambiance. Putting the woofers horizontally (on either side of the tweeter) will reduce the horizontal dispersion creating a somewhat more localizable source. This does introduce more floor/ceiling reflections though since it's wide side is now vertical.

I'm not sure what the mid horn's measured dispersion looks like or the reason for Klipsch orientation, but it visually appears to be installed to have narrow-horizontal dispersion in the KLF but wide-horizontal dispersion in the C7? Klipsch literally turned the whole speaker on it's side... but it's hard to give a definite answer why without the hard data.

Although it seems to go against my previous reasoning there may have been other motives such smoothing out in-room frequency response due to the driver's polar patterns.

Researching the popular MTM (mid, tweeter mid) speaker design movement would probably reveal more on the interaction of drivers working at different frequencies with each other.

I like the idea of the removable motorboard... as there are no right or wrong answers...
Rob

PS: preserving a perfect timber match (with three identical speakers) is also a valid method of approach...

[wstrickland1]

So, in short, what is the recommendation, if you were only gonna do it once:

speaker laying on its side, woofers on either end, mid/tweet in the middle, horn orientation is....................................?

[formica]

Initial guess using KLF20 (or 30) parts... would be the same orientation as in the KLF20 to accomodate the tweeter.

[DrWho]

My

reasoning comes from that, in general, you'd like the centre channel to

act more as a point source for the voices while the left and right

channels to add the ambiance. Putting the woofers

horizontally (on either side of the tweeter) will reduce the horizontal

dispersion creating a somewhat more localizable source. This

does introduce more floor/ceiling reflections though since it's wide

side is now vertical.

You actually got it backwards there (in a way)...

The dispersion of sound is very much like the dispersion of light. If

you stick a flashlight on top of your speaker with the nominal

dispersion of the driver in question, then everything the light hits

will be recieving the direct sound from the speaker. Anybody sitting in

these locations will hear the sound source as if it were coming right

from the bulb on the flashlight (just like we can see where the source

of light is coming from). Whether or not this dispersion pattern is

wider or narrower will have no impact on the localization of the sound as

long as the listener has the light shining on him. (so anywhere inside

the dispersion pattern we hear the source from the same location

regardless of the dispersion). However, if a person is sitting in a

spot that the light isn't shining on, then that person is not going to

hear the direct sound from the speaker, but rather the majority of what

he will hear will be reflections from throughout the room. The person

sitting off-axis will then usually percieve the sound source as coming

from somewhere else! (there are some psychological factors that make

this less noticeable, but closing your eyes makes it very

obvious...especially with pink noise)

One side note...the dispersion of the speaker isn't such a straight

line like the edge of a flashlight beam, but rather it is a gradual

roll-off. Higher frequencies tend to fade faster as you move off-axis

which results in a typical muddy sound when standing beside a speaker

(as compared to standing in front). One of the reasons narrower

dispersion speakers tend to image better is because they reduce the

number and magnitude of reflections occuring in the room, which

essentially confuse our ears as to the true location of the sound

(because we can locate the direction of the reflection source as well

as the speaker itself). Generally the direct sound is louder than the

reflections and our focus is on the screen so this isn't a big deal,

but after you've heard a good acoustical environment you will never go

back. Right now in my new apartment I've got a cieling reflection that

is driving me nuts so I will be looking into some of the skyline RPG's

if I ever come across some money. Some diffusion on the rear wall would

be nice too,

[redtop]

Very enlightening replies guys! Really educational stuff.

My nearly finished dedicated theater room is an echo chamber right now,

but once I get ready to setup the audio system, I will be adding a

bunch of absorbtion panels to tame the reflections. I'm starting

with broadband treatments in all four corners (floor to ceiling)

to tame the bass, 2 inches of acoustic cotton on the front wall behind

the screen wall, and then panels for the high frequency first

reflection points. Going to use the old mirror trick to find

those so the

recommendations on room treatments are well taken. Will add more

panels as needed. This is my first experience with room

treatments, so I'm planning on doing it in phases and listening as I

go. I don't want the room too dead.

I especially like the idea of building the cabinet with 3 motor boards

to house the drivers separately. That will make the testing

process so much faster and easier. IMO, this has become a great

informational thread for all of those considering a custom center and I

hope it's as helpful to Billy as it is to me.

[wstrickland1]

very helpful indeed. nice thread guys. thanks

[formica]

Whether or not this dispersion pattern is wider or

narrower will have no impact on the localization of the sound as long

as the listener has the light shining on him. (so anywhere inside the

dispersion pattern we hear the source from the same location regardless

of the dispersion).....

........ One of the reasons narrower dispersion speakers tend to image

better is because they reduce the number and magnitude of reflections

occuring in the room, which essentially confuse our ears as to the true

location of the sound (because we can locate the direction of the

reflection source as well as the speaker itself).

You shouldn't be allowed to play both sides esp in a single post. []

There are proponents to both designs... as each has it's strong

and weak points. Even the different surround standards don't all

agree (THX, Dolby Prologic I, DVDA, etc...).

In the case of these custom centres, I don't believe a vertical format

is practical for this thread to begin with so, in a sense, it becomes a

mute point.

RPG... hmmm... lottery, yes.[8-)][] There are cheaper products which may achieve what you'd like, but won't look as nifty...

Where's that plane to Cuba, I'm low on rum...

Rob

[DrWho]

In the case of these custom centres, I don't believe a vertical format is practical for this thread to begin with so, in a sense, it becomes a mute point.

I only brought it up because he mentioned using an acoustically transparent screen which opens up that option [] Besides, I think it's important to realize the sacrifices made that make the center channel a practical option...because then it shows how these compromises can be minimized (ie, moving the woofers as close together as possible, or implementing an arrayed crossover like in the reference lineups).

Btw, I'm also not trying to claim that designs with spreadout woofers sound awful...it just lowers the frequency at which the comb-filtering starts to occur which means there is a larger frequency range where it could be an issue (keep in mind that comb-filtering is going to happen no matter what with any non-coaxial speaker...one of the reasons I love Tannoy actually, but let's not go there). Since it costs nothing to construct a cabinet with the woofers closer together I figured I'd point it out because the trend seems to be the opposite.

One other note, when experimenting with the multiple baffle configurations, be sure to listen on- and off- axis from the speaker, or if every seat is on-axis then listen at every listening position and choose something that sounds good everywhere.

[redtop]

And a good suggestion it was Dr, if for no other reason than it offered

another option for placing a center channel that I had not seen

suggested on this board in the 3 years I've been hangin' around.

I will be sure to test several configurations and orientations.

You guys will be the first to hear the results. It will probably

take up to a month though, given my schedule with completing the

theater room. I do need to get to done first...[]

While we're on the subject of vertical orientation I have another

question...if you look at the new Klipsch THX series on the website,

all of the horns in speakers in the front array are oriented with the

widest dimension of the horn (60 degree) vertically like the C7.

It's a 2 way speaker system, so that changes the variables vs. the

KLF-30's, but it make me wonder if there is some sonic advantage that

we are missing here?

As a side note, I have a lot of respect for the new THX Ultra

system. I have a young friend with perfect pitch and a solid

musical background that got to listen to the THX Ultra system in action

at Klipsch headquarters. He said it was so sweet sounding it

almost brought him to tears! He's now saving his pennies...[]

[wstrickland1]

Ok, Wifey says FedEx delivered the stuff......"a few small parts, ehh....the delivery guy could hardley carry it in....."(Wifey sed)

anyway, now its box time

Billy

[Jay L]

this is what you will want it to look like

[wstrickland1]

this is what you will want it to look like

OK, there may be a problem with the size, the largest I can go is 33" wide x 12" high x 10" deep. This is the size. Too small perhaps but this is the size for now. Maybe bigger later. Does anyone see any major problems with that for the time being?

[DrWho]

this is what you will want it to look like

OK,

there may be a problem with the size, the largest I can go is 33"

wide x 12" high x 10" deep. This is the size. Too small

perhaps but this is the size for now. Maybe bigger later.

Does anyone see any major problems with that for the time being?

Which drivers were you going with again? And how large was the original

cabinet housing them? One thing you can do to increase the apparent

volume of the cabinet is to fill it with poly-fil. There's ratios

floating around somewhere that indicate exactly how much larger it can

make it appear to the drivers (this works really well for sealed

designs).

[wstrickland1]

I'm using new KLF 20 drivers and crossover, (2) 10" woofers, the K-77-K Tweeter and K 52/K 703 Horn. A stock 20 is about 40.75" x 12" x 16" deep. It also has (2) rear ports.