Heritage Center Channel

[Duke Spinner]

You might want to consider the ST-350 as well.

S. F.

have you used the ST-350 .. A,B or C..

in any Klipsch application ..??

[boom3]

One caveat about rear ports. In large cabinets the distance between the rear port and the woofer(s) on the front panel can be a close to the wavelength of a frequency the woofers are pushing...leading to destructive interference. With a front panel box, that distance vs. wavelength is a frequency far above the woofer's operating range.

[DrWho]

So here's just a rough sketch of the motorboard layout drawn to scale. It comes to about 14" x 43" which is probably a bit huge...especially considering the K400 horn extends 2 feet backwards.

I have some ideas for making the motorboard smaller, but y'all will have to bear with me as I crunch through a few numbers. Considering the height and depth is pretty much fixed, the only way it can be made smaller is by making it not as wide - since most people have screens larger than 3 feet wide I'm not sure how big of a concern this is...

[J.4knee]

43" wide? No probelm I can do it! I need to send you dimesions on a 511B too I'll try to get them for you today. Using this horn will make it both taller and wider obviously.

[Guest " "]

Duke Spinner

I have a few pairs of ST-350A's and ST-350B's and tried them both on top of my 2004 LaScala's as well as mounted inside some K-horn clones.

I would discribe the sound as wider in the same sense the 511b or 811b widens the sweet spot vs regular k-400 horns.

So for folks that are trying to juggle their k-horns around to find the sweet spot, and don't want to spring for some jbl 2405's, the ST-350 A/B is a good choice.

It uses the same voice coil as the t-35/K-77.

[J.4knee]

511B dimensions:<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

W-23 7/16 (when you account for the little pooch out they do in the middle)

H-10 9/16

D-21 7/8 (with adapter and K55M mounted)

Lips dimensions:

W-20 7/8

H-9 1/8

D-4 ½

[BEC]

Doc,

Sent you an email.

Bob Crites

[colterphoto1]

any way we can get by with ONE 12"?

[jwc]

any way we can get by with ONE 12"?

Exactly. Yes you can with resonable compromises.

[bodcaw boy]

any way we can get by with ONE 12"?

i agree......doc any particular reason that you are using 2 twelves?

boy!!

[DrWho]

Well the original goal was to maintain the same system sensitivity so that minor if any mods to the network were needed. I also like the symmetry (even though it's worse for horizontal off-axis performance).

Why not go with dual 12's? []

[jwc]

Doc. I agree with you in that the two 12 inch woofers and the K77/K55/K400 would be the way to go. It was just a size and shape issue for me.

I had two alnico K22's and ended up using just one. I had a lot of different drawings to try two of them and it was just too big for the spot I wanted to place the center.

I say you do it. It would be the better ay to SPL match.

jc

[colterphoto1]

how's about one of them thar Tractrix horns for the mid? Saves motor board space and depth in the cabinet. 43" is really really huge.

[bhendrix]

Or one of Bob's Pyle Horns . . .

http://www.pyleaudio.com/itemdetail.asp?brand=pylepro&cat1=Pro%20Audio&cat2=Horns%20and%20Tweeters&model=PH2380P

The Pyle PH2380P is 17 1/4" wide vs. the K400 at 18 3/8" but,

the PH2380P is 11" deep including the K-55 vs. the K400 w/ K55 at 23 1/2" deep.

This is the horn Bob uses in his Cornscala II's and sounds really close to the K400.

This would give you Heresy-like cabinet depth (13 1/4") x 15 1/2" high (Heresy width) x 42" wide, a perfect riser stand for a flat screen TV. []

If fact, this cabinet would be the same size as two Heresy's laid end-to-end.

[jwc]

Oh. By the way. I have an extra Alnico K22 if anyone is interested.

jc

[bodcaw boy]

Well the original goal was to maintain the same system sensitivity so that minor if any mods to the network were needed. I also like the symmetry (even though it's worse for horizontal off-axis performance).

Why not go with dual 12's? []

well a center is wise to keep the same timbre and spectral balance of the left and right. if you don't use a tapered array network, then you are going to get some serious lobing depending on the crossover point. if you get into the lobing, now the center might not sound like the left and right. that's all..[]

boy!!

[sunburnwilly]

Here it is .

No need to look any farther .

[DrWho]

So how does one go about a taperred array without losing efficiency? [*-)]

I did some "rough calculations" using the wonderful scaled world of MS Word and figured that a 335Hz crossover would yield a 72 degree horizontal coverage pattern. 500 would be 44 degrees.

btw, 4knee I haven't forgotten about you yet...just haven't been around.

[bodcaw boy]

what coverage pattern did you assume each woofer would have at 335 and 500 hz?

boy!!

[DrWho]

I assumed 360 degrees just to find the first destructive interference point and then calculated back to make sure it was within an acceptable coverage from each speaker...in other words, I just drew lines [] (one line was a given length and the other line was 1/2 wavelength shorter. Because of the fixed distance between drivers this will force a single triangle. I then drew a line back to the center of the speaker and measured its angle.)

Though now that I think about it some more, I was finding the angles of the troughs - the effective -6dB point is going to be slightly narrower.

To be honest, I'm not entirely confident on how to accurately predict coverage. I've always gone by the rule of thumb to have same information drivers be within 1/4 wavelength of their top frequency and then just not think about it. If anyone knows of any better ways than manually crunching wavelengths and known phases let me know []

I might have to present an alternative approach I've been thinking about which should alleviate both the side of the motorboard issues and the lobing issues....inspired by the guys over at EAW - yes I know, I need to lose the other pinky toe []