Dumb question - ME10 horn

AJ

Member
2003-08-01 7:06 am
Oregon
Go ahead and laugh - I can take it. :D

I have a coupla B&C ME10 horns here and my lack of experience is really showing. The horns are square with a 90X60 degree coverage and I'm not sure which is 90 and which way is 60. There's a coupla raised bosses molded into the flange which probably indicate direction, but which way? There's two different curves but I don't know what a hyperbolic cosine horn looks like so I'm confused. There's gotta be a rule of thuimb here based on the two different profiles, but it's lost on me at the moment. Thanks for the help.

[IMGDEAD]http://www.lakefly.com/images/me10.jpg[/IMGDEAD]
 
Wo AJ! You'll be king of the OB hill with that system. I'm collecting pieces for one Lil Buddy and ME10/DE10 per side; will add some 15's later but my boxed 10" subs for now. I'll need to know that orientation as well- glad you asked. One of the horn mavens should be along shortly with the answer. Can you tell what size and type of screw is needed to mount the horn?

Thanks,
Jon
 

AJ

Member
2003-08-01 7:06 am
Oregon
"Can you tell what size and type of screw is needed to mount the horn?"

A number 6 or 8 will do just fine. The holes aren't counterbored, they're tapered, so a button head will want to put pressure on the holes at the edges of the screw - might setup for cracking. A typical wood screw with a tapered head might be better.
 

AJ

Member
2003-08-01 7:06 am
Oregon
"BTW I was referring to the horn to driver mount holes for orientation."

heh heh...yeah I looked at the pictures too. problem is there's 4 driver mounting holes so it kinda puts you back at square one. The raised bosses on the flange I think are the key, but they're just like the mounting holes - it can mean either way.

The profiles of the two curves should be obvious to any horney worth his salt; unfortunately, that's not me yet. I need at least another week before I know everything. :D
 
Well, don't have any specific knowledge of this horn, but in general let me ask a few question, and add a conclusion.

You said this horn has 90 degree dispersion on one plane and 60 degree dispersion in the other plane. Is that correct?

Next, can I assume the horn is truly square; height and width are the same?

If the above is true, then I would assume that the adjacent (at right angles) flares on the horn are NOT the same.

If I'm still on the beam so far, then I would say that the horn sides with the greatest flare have the greatest dispersion, and presumably you would want that on the horizontal axis, so your dispersion would be 90 degrees on the horizontal and 60 degrees in the vertical.

If the flares are uniform and the horn is truly square, then it's anyone's guess.

For what it's worth.

Steve/bluewizard
 

AJ

Member
2003-08-01 7:06 am
Oregon
Hi Steve

Yeas, it's truly square and yes there are two different profiles. I did exactly what you're talking about by rotating the horn and looking for different indications of dispersion, but it's still left me guessing. Two paralell sides have a more-less constant looking profile, and the other two are more ambiguous. It's not as clear cut, to me at least, which is which.

Bonjonno - Another word about hardware for mounting. I didn't get any driver mounting hardware so I had to go buy some M5 X 11mm SHCS - just a heads up.
 
AJ

I just placed my order at Parts Express. heh heh. Karma kicks my butt for the third time this week :cannotbe: I was curious about the bolts from driver to horn and imagined they HAD to be included. Live horny and learn. No problem; ACE has the necessary bolts. I ordered a bag of #8 panheads for all the other big drivers I'll be getting; this horn may mount well with sheet rock screws if I'm careful.

That's a pisser about the horn having 4 mounting holes for the driver. Just to confuse matters I guess. Once you get it set up I bet it'll be easy to hear which way is right.
 
Just a guess from the photos, but there does seem to be a subtle difference between the flare of the horn.

One flare seems constantly flaring, and the other seems more shallow. The one with the constant flare is the 90deg horizontal. The other is the 60deg.

I've created a drawing the implies what I am getting at. Again, this is just best guess from several photos; it could be completely wrong.

Steve/bluewizard
 

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AJ

Member
2003-08-01 7:06 am
Oregon
Here's my best guess.

This is what the two sides look like from the outside. Viewing the inside, you can also see two different profiles.

[IMGDEAD]http://www.lakefly.com/images/side1800.jpg[/IMGDEAD]

[IMGDEAD]http://www.lakefly.com/images/side2800.jpg[/IMGDEAD]


These two shots I think are the clincher. In the first one, the 90 degree sides of the plywood find a very obvious self-centering tangency in the final flare of the horn. The curve is a constantly changing profile throughout. In the second shot, rotated 90 degrees, the last half of the horn is pretty much straight and there's no change in the profile all the way to the mouth. The plywood won't self-center because there's no point anywhere on this side that approaches 90 degrees.

[IMGDEAD]http://www.lakefly.com/images/tan90.jpg[/IMGDEAD]

[IMGDEAD]http://www.lakefly.com/images/tan60.jpg[/IMGDEAD]

Looking just at the outside, I would've guessed incorrectly - the profiles on the outside, being the compound angle of the intersections of two planes, doesn't relate to what the plywood shows. Anyway, the bottom line is that the small raised bosses molded into the flange should be oriented vertically for the 90 degree dispersion to be horizontal. That also lines up with the picture at PE. My ME10 PDF doesn't show those markers.

That's my story and I'm sticking to it. :)
 
I was right there are two different profiles to the horn flares.

The top photo from the side, shows the least flare or curve. The side are straight in the beginning and flare at the end. This is the 60 degree dispersion flare.

The second photo from the side, show pronounced flare at the throat, and I think this is the 90 degree dispersion side. These sides should be on the horizontal plane.

Keep in mind that 90 degrees is the dispersions angle of the sound not the angle of the flare.

Does anyone disagree with me?

It is kind of a tough call because one is straight and wide at the throat, with flare at the end. The other flare significantly at the throat, then becomes straighter at the end.

Steve/bluewizard
 

AJ

Member
2003-08-01 7:06 am
Oregon
hey Steve

"I was right there are two different profiles to the horn flares."

I mentioned that in the original post - it's easy to see there's different flares, but it's not all that clear as to which is which. When I think of other rectangualr horns I've seen that have different coverage patterns for horizontal and vertical, the flares controlling the vertical dispersion seem to often times be closer to straight, with the sides controlling the horizontal dispersion having the true profile of whatever type of flare the horn is being made to. Just an observation, that may not hold much water. :)

"The second photo from the side, show pronounced flare at the throat, and I think this is the 90 degree dispersion side. These sides should be on the horizontal plane."

Well that's what confuses me - those sides are pretty much straight from at least halfway from the throat. If a straight line is a hyperbolic cosine surve, then why don't they just call it a straight horn? You see where I'm going with this? :)

The sides 90 degrees to it, have a well defined, constantly changing flare with a very disinctive tangency at 90 degrees. If that's the vertical dispersion side, then the other side that you say should be the horizontal, is a straight sided conical for the last half and it pretty much stays at ~60 degrees. It's a mystery. :)

What I'm trying to say, is that the outside doesn't necessarily tell you what's on the inside.