ok to put woofer above waveguide in SEOS speaker? - AVS Forum
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post #1 of 9 Old 11-06-2013, 04:02 PM - Thread Starter
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I'm getting ready to make some SEOS-15 / DNA-360 / TD-15M tower speakers, using the same drivers and crossover design that I used for a center channel here.

I want to make some interesting and attractive (to me smile.gif) cabinets. One design idea is to put the woofer above the waveguide, but I'm not totally sure of the acoustic challenges, so I started this thread to ask for advice.

Here's what I think I know:

1. The waveguide should be approximately ear-level in height. So if I put the woofer above, the speaker will need to be pretty tall.

2. I've read about, but don't totally understand, that there is some axis that might point slightly up or down for a given speaker. It is unusual to listen with your ears below the waveguide, but more common to listen above, such as when you are standing. So I would guess that if this is an issue, a speaker is generally designed to please people standing rather than people laying on the floor. Putting the woofer above the waveguide would invert this design choice. Is there anything I need to lookout for here?

3. I don't know how tall the speaker will be, but it seems like it could be bad if the woofer ends up equidistant from floor and ceiling. I will seek to avoid that.

Is there anything else that I should watch out for?

Thanks,
-Max
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post #2 of 9 Old 11-06-2013, 04:33 PM
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You've pretty much nailed it.

1. This is why the woofer is usually below. To tall for most people.

2. It's the design axis, or frontal lobe, or wave front, or what ever nick name someone thinks of. Most of the time it's aimed straight out. But sometimes things work out that it's a little up or down. Often, up is preferred to down. So, yes, you'll be backwards.

3. Yup, try to stay odd distances.

You won't get as much floor loading. This might be good or bad. But often the floor starts to help a little in the bass depending on the height.
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post #3 of 9 Old 11-06-2013, 04:48 PM
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this might help:

http://www.rane.com/note160.html

with two sources and a crossover, you get some cancellations based on the fact that at some angle and some wavelength the drivers will be 180 degrees out of phase with each other. the result is what folks call "forward lobes". the article will explain more.

this might also help as another way of explaining the same idea:
http://www.avsforum.com/t/1490928/big-horns-experiments-ae-td15m-ae-td15h-seos24-iwata-300-jbl-beryllium-bms#post_23785832
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post #4 of 9 Old 11-07-2013, 08:33 AM
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Quote:
Originally Posted by LTD02 View Post

this might help:

http://www.rane.com/note160.html

with two sources and a crossover, you get some cancellations based on the fact that at some angle and some wavelength the drivers will be 180 degrees out of phase with each other. the result is what folks call "forward lobes". the article will explain more.

this might also help as another way of explaining the same idea:
http://www.avsforum.com/t/1490928/big-horns-experiments-ae-td15m-ae-td15h-seos24-iwata-300-jbl-beryllium-bms#post_23785832

^This was very useful info, Thanks.
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post #5 of 9 Old 11-08-2013, 10:50 AM
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What is the intended usage space for the speaker?

Obviously, a speaker sitting on the floor in a room where you expect to listen to it while standing will call for different layout than a speaker that is dedicated to audio playback while sitting elevated off the floor (on a stage perhaps) while the listener is expected to be reclined back in a chair.

Also, if you're looking to use these for movies, you may prefer to have the tweeters located so that they sit half way up/down w/ respect to the screen. You don't want the directional, high frequencies coming out a foot below the bottom of the screen, for example.

-Suntan
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post #6 of 9 Old 11-08-2013, 11:48 AM
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Sorry to hijack, but I have a question about this too. I want to do Tempest LCR because I really want all 3 to match, but I don't have an AT screen and don't plan on having one in the near future. I can make the left and right whatever height I want obviously, to line up with ear level when sitting, but the center channel may be a little lower than the L and R because of its position below the screen, and may be a BIT lower than ear level, probably only by a few inches. I'll do some measuring, but is there a standard level of play when it comes to vertical dispersion with these that is acceptable? I can cure it by raising the screen to make more room to raise the center channel a bit, but don't want the screen too high, as I'm pretty happy with the height right now.
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post #7 of 9 Old 11-09-2013, 11:35 PM
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^^ the speaker can be tilted back slightly to aim the horn right at your head where you sit.

Listen. It's All Good.
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post #8 of 9 Old 11-10-2013, 11:25 AM
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Awesome, thanks, LTD02, just what I was looking for smile.gif
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post #9 of 9 Old 11-10-2013, 11:39 PM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post

this might help:

http://www.rane.com/note160.html

with two sources and a crossover, you

Thanks LTD02. Everyone interested in speaker design should read that. It starts with some extremely accessible descriptions of what happens as the listener moves up and down in front of a speaker. It gets more technical at the end, but I think I still grokked most of it.
Quote:
Originally Posted by tuxedocivic View Post

You've pretty much nailed it.

1. This is why the woofer is usually below. To tall for most people.

It sounds like 1/4 (or 3/4) the height of the room is more ideal for woofer height, too, which seems much easier with the woofer below.
Quote:
2. It's the design axis, or frontal lobe, or wave front, or what ever nick name someone thinks of. Most of the time it's aimed straight out. But sometimes things work out that it's a little up or down. Often, up is preferred to down. So, yes, you'll be backwards.

3. Yup, try to stay odd distances.

You won't get as much floor loading. This might be good or bad. But often the floor starts to help a little in the bass depending on the height.

Thanks for the tips and info.

-Max
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