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3ll3d00d's Avatar 3ll3d00d 03:37 PM 01-22-2015
I posted this question on my own thread but I think it's a more general question about how to best employ a SEOS in a room. I've tried searching this thread, and other forums, but it's hard to find a clear answer so I wonder if someone can confirm whether my thinking is accurate.

My current thinking is to build a SEOS10 over an 8" in a low profile on wall enclosure. A polar response of the SEOS10 was posted back in post #1393



As I understand it, this shows that +/- 22.5 degrees is approximately the range in which it is pretty much consistently at "full power" (i.e. minimal variation). As you get further off axis then there is some rolloff such that by +/- 45 degrees then you're 6dB down at the top end.

Applying this to an actual room then we can see the disperson of my L speaker below. The area I want to cover with sound is in blue, this requires output (from a flat on wall speaker) over 0-30 degrees. The area that produces 1st reflections off the ipsilateral wall is in red, this requires output from ~-25 to -50 degrees.



Therefore if I mount the speaker flat on wall then two things will happen

1) the 1st reflections from the L wall at the left most listening position will be strong
2) the direct sound at the right most listening position will be >3dB down

This makes me think the correct thing to do will be to angle the baffle by ~10 degrees (to point towards the opposing wall) which will mean

1) the listening position is in the -10 to +20 degree range == sweetspot!
2) the 1st reflections off the L wall will be in the -35 to -60 degree range (i.e. in the region of ~8-12dB down)

If this correct? Is there anything else I should consider with this positioning that I'm missing?
Attached: dispersion.jpg (70.8 KB) 

HopefulFred's Avatar HopefulFred 03:45 PM 01-22-2015
You're on the right track, but you haven't taken the idea far enough. If you toe the speaker in such that the nearest listener is outside that window by a few degrees you can enlarge the sweet spot considerably. The near wall reflections then get even lower in intensity.

Bwaslo wrote and posted a very good and compete discussion of time/intensity trading at diysoundgroup forums. Please read that.
http://www.diysoundgroup.com/forum/index.php?topic=20.0
3ll3d00d's Avatar 3ll3d00d 04:31 PM 01-22-2015
Thanks for the link. What happens when you put a C speaker into the middle of such a toed in LR?

Unfortunately I cannot accommodate that degree of toe in due to the on wall mounting & my depth constraints requirement to mount on wall. I think ~10 degrees is the most I can realistically manage (needs a 2" offset on the baffle given a 12" wide speaker)
Eyleron's Avatar Eyleron 06:11 PM 01-22-2015
That's why acoustic transparent screens are so helpful...you can build a baffle wall shaped how you need it, and it's hidden behind screen wall.
LTD02's Avatar LTD02 06:28 PM 01-22-2015
as fred mentioned, these things do best when toed in or the speaker in front of the off axis listener will dominate and steer the sound off the center of the screen. not the end of the world if using a center though. this concept was discussed by klipsch in...1975 (see dope from hope 1975 https://community.klipsch.com/dope/D...0801_v15n2.pdf). for some reason we seem to need to keep rediscovering it. :-)
tuxedocivic's Avatar tuxedocivic 08:16 PM 01-22-2015
As someone who has a flat baffle wall, it's ok for movies with a center. For stereo music, my stand alone speakers can make a better image when toed in.
FriscoDTM's Avatar FriscoDTM 09:13 PM 01-22-2015
Quote:
Originally Posted by 3ll3d00d View Post
Unfortunately I cannot accommodate that degree of toe in due to the on wall mounting & my depth constraints requirement to mount on wall. I think ~10 degrees is the most I can realistically manage (needs a 2" offset on the baffle given a 12" wide speaker)
How about building out small false walls covered in decorative AT fabric at ~45 degrees in each of the bottom corners, with the L/R in the corners pointed at each opposite seat and the balance of the space serving as bass traps?
3ll3d00d's Avatar 3ll3d00d 02:11 AM 01-23-2015
Quote:
Originally Posted by FriscoDTM View Post
How about building out small false walls covered in decorative AT fabric at ~45 degrees in each of the bottom corners, with the L/R in the corners pointed at each opposite seat and the balance of the space serving as bass traps?
I would like to do something like this however it requires some structural changes to the room (the door needs to move) so that is a 2-3 years down the line.
3ll3d00d's Avatar 3ll3d00d 02:55 AM 01-23-2015
Quote:
Originally Posted by tuxedocivic View Post
As someone who has a flat baffle wall, it's ok for movies with a center. For stereo music, my stand alone speakers can make a better image when toed in.
does that mean the image is absolutely poor without sufficient toe in or that it is still good, just not as good?
Tip24/96 03:28 AM 01-23-2015
Quote:
Originally Posted by 3ll3d00d View Post
does that mean the image is absolutely poor without sufficient toe in or that it is still good, just not as good?
Why not build the toe into the baffle as you previously mentioned? It doesn't have to be a steep angle, just enough to direct the image inward towards the listening position.
3ll3d00d's Avatar 3ll3d00d 03:32 AM 01-23-2015
Quote:
Originally Posted by Tip24/96 View Post
Why not build the toe into the baffle as you previously mentioned? It doesn't have to be a steep angle, just enough to direct the image inward towards the listening position.
that's what I was thinking, something like this

Click image for larger version

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what I was asking, in the quoted post, was for a view on the relative quality of the stereo image when using markedly less toe in.
Attached:
tuxedocivic's Avatar tuxedocivic 07:59 AM 01-23-2015
No the image is still good. Even venter channel fooling good sometimes. But not quite as wide or precise as my stand alone SEOS speakers with toe in. But I've never found it to be a factor when watching movies with LCR running. I only hear the difference in stereo.

Oh that's a completely flat baffle wall. No toe at all. So you'd be better off than me. FWIW, I'd give up my speakers before my baffle wall.
SilverSPL's Avatar SilverSPL 08:47 PM 01-23-2015
Was quite the undertaking to read all 400+ pages but I did it. Took me about two months of reading a little bit every day. Also looked into all the links to other pages and forums along the way. Reccomend everyone doing it, learned a lot in reading everyone's posts. You will have far less questions and more of the answers.

Erich thank you for everything you have done!

I will soon be purchasing some speakers from you for my home theater that I'm building in my unfinished basement. Once the basement get a little further along I'll start a build thread of my basement and show my integration of the speakers into the walls.
dtsdig's Avatar dtsdig 08:12 AM Yesterday
Quote:
Originally Posted by SilverSPL View Post
Was quite the undertaking to read all 400+ pages but I did it. Took me about two months of reading a little bit every day. Also looked into all the links to other pages and forums along the way. Reccomend everyone doing it, learned a lot in reading everyone's posts. You will have far less questions and more of the answers.

Erich thank you for everything you have done!

I will soon be purchasing some speakers from you for my home theater that I'm building in my unfinished basement. Once the basement get a little further along I'll start a build thread of my basement and show my integration of the speakers into the walls.
That's really awesome! I've read the majority of it "live" and I've also started at the beginning and gotten through the first 150 pages or so but to read the entire thing is quite the feet!
clausdk's Avatar clausdk 11:25 PM Yesterday
Quote:
Originally Posted by SilverSPL View Post
Was quite the undertaking to read all 400+ pages but I did it. Took me about two months of reading a little bit every day. Also looked into all the links to other pages and forums along the way. Reccomend everyone doing it, learned a lot in reading everyone's posts. You will have far less questions and more of the answers.

Erich thank you for everything you have done!

I will soon be purchasing some speakers from you for my home theater that I'm building in my unfinished basement. Once the basement get a little further along I'll start a build thread of my basement and show my integration of the speakers into the walls.
Congrats! Lets hope
they become available soon again.
Tip24/96 05:19 AM Today
Do any of you fellows happen to have any experience building a slightly curved baffle wall? I am want to build a baffle wall in my ht room but make it with a built in curve in order to toe in my left and right speakers. If any of you guys have any experience with something like this, would you mind sending me a PM so that I can pick your brains and figure out how to do this properly?
Mfusick's Avatar Mfusick 05:21 AM Today
Dedicated construction forum.

Also PM is insulting to some people, like you are special and only you are worthy of the information and time. You'll get a lot more information faster with a public thread in the proper area.

Typical baffle wall is mdf + drywall with GG in between layers.
Doradoguy 10:47 AM Today
Quote:
Originally Posted by Tip24/96 View Post
Do any of you fellows happen to have any experience building a slightly curved baffle wall? I am want to build a baffle wall in my ht room but make it with a built in curve in order to toe in my left and right speakers. If any of you guys have any experience with something like this, would you mind sending me a PM so that I can pick your brains and figure out how to do this properly?
I'm new to HT but I have built several curved walls. What actually are you having trouble with the layout or the construction side. To give you clue. Find the center of the wall, pull a string perpendicular ( from center of wall out toward the middle of the room. ) secure end of string opposite of wall. This is the center of your string compass. The distance you will have to play with depending on how much of a radius you want. Now hold a marking device on other end of string and rotate around the center point. Once you have determined the correct distance, measure string and head to your work area and repeat on bottom and top plate. This will be your front edge. Now add the thickness of your wall to the string and repeat. This will be the back edge of your plates. Now cut out and sandwich your studs in between top in bottom plate. This will probably have to be done in place. Mount top plate to rafter and bottom plate to floor. Toe nail studs in place.

Well this should give you an idea.

Now am off to find the construction thread.
foraye's Avatar foraye 12:07 PM Today
Quote:
Originally Posted by Tip24/96 View Post
Do any of you fellows happen to have any experience building a slightly curved baffle wall? I am want to build a baffle wall in my ht room but make it with a built in curve in order to toe in my left and right speakers. If any of you guys have any experience with something like this, would you mind sending me a PM so that I can pick your brains and figure out how to do this properly?

There are a few different ways to build a curved, you may want to start in the Dedicated Theater Design and Construction Forum!. Its not specific to theaters so searching general construction sites might help also... click HERE.

Good Luck!
3ll3d00d's Avatar 3ll3d00d 12:32 PM Today
for a "simple" 2way and a passive XO, am I right in thinking that the SEOS-10 is best used with an 8" and the SEOS-12 with a 10"? The discussion from TD10M and SEOS10/BMS 4550 build questions. seems to point in that direction as it talks in terms of requiring quite steep slopes to ensure a sharp transition from 1 driver to the other & hence this probably isn't easily implemented in a passive setup.

The context is that I'm weighing up whether a SEOS-10 over a TD10 is feasible without going active.
Gary Lightfoot's Avatar Gary Lightfoot 12:53 PM Today
Quote:
Originally Posted by Tip24/96 View Post
Do any of you fellows happen to have any experience building a slightly curved baffle wall? I am want to build a baffle wall in my ht room but make it with a built in curve in order to toe in my left and right speakers. If any of you guys have any experience with something like this, would you mind sending me a PM so that I can pick your brains and figure out how to do this properly?
This guy built an Erskine designed theatre that had around 8 degrees toe-in. It's not curved but the baffle the left and right speakers are mounted in are just angled:

Another DownUnder theatre

Gary
tuxedocivic's Avatar tuxedocivic 12:57 PM Today
3113dood, there are differing views on this. I tend to feel its best to play it safe and generally prefer to not pair huge woofers with small waveguides. Better to keep the sound within the waveguide rather than coming off the round overs. Also allows for more relaxed XO slopes.

However, a SEOS 10 with 10" woofer is no issue at all. Easy implementation.
Gary Lightfoot's Avatar Gary Lightfoot 01:21 PM Today
Didn't the original Cheap Thrill have a 15" woofer with a 12" CD waveguide? I was thinking of doing something similar, but wonder if the smaller wg (PH612) would have a bad effect. I'll be using them as LCR behind an AT screen. As I understand it, a larger wg over a smaller woofer is preferable, so wonder how the cheap thrill performed in that regard

Gary
Sarge39 01:37 PM Today
Is there any timeline for the Diysoundgroup site to come back up to order speakers? The more I read while I wait, the speakers I want keep getting bigger for my build.... LOL
mt2mt2's Avatar mt2mt2 03:39 PM Today
Quote:
Originally Posted by Sarge39 View Post
Is there any timeline for the Diysoundgroup site to come back up to order speakers? The more I read while I wait, the speakers I want keep getting bigger for my build.... LOL
Me too!!!! Started out looking at the Fusion 8.... Now the Fusion 15s look about right!!!!!
Sarge39 04:57 PM Today
Yeah, 2 sentinels and 5 cinema 88s.. Thats what I am thinkin now.. Wonder if that's overkill for a 15 x 24 room? Also 2 um18 subs 4 cu ft sealed enclosures, Inuke6000 Dsp amp.... Origianlly was cinema 8, s 8 mtm center, and 4 alchemy 8 for surrounds
LastButNotLeast's Avatar LastButNotLeast 05:00 PM Today
Overkill? Here?
You must be kidding.
Face2's Avatar Face2 05:17 PM Today
Quote:
Originally Posted by 3ll3d00d View Post
for a "simple" 2way and a passive XO, am I right in thinking that the SEOS-10 is best used with an 8" and the SEOS-12 with a 10"? The discussion from TD10M and SEOS10/BMS 4550 build questions. seems to point in that direction as it talks in terms of requiring quite steep slopes to ensure a sharp transition from 1 driver to the other & hence this probably isn't easily implemented in a passive setup.

The context is that I'm weighing up whether a SEOS-10 over a TD10 is feasible without going active.
I'm using a TD10M and SEOS12/DNA360 in a two way. A larger guide will allow an easier transition and shallower slopes as was alluded to already. But due to the impedance profile of the CD, the crossover really won't be much simpler.
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