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Budget Eminence Coaxial surround build!!! - Page 24

post #691 of 863
Quote:
Originally Posted by NicksHitachi View Post

Hey Mhutchins,

A couple opinions on some of that.....

1. Remember those models are free space models so assuming the surrounds are mounted on the wall or very close to it, add 3-6db down at 80-100Hz from boundary reinforcement. Probably closer to 6db.

2. I would personally like to see the port resonance a little lower out of the midrange but thats just me. I'm personally a fanboy of sealed for this an many other reasons.

3. Make sure your using LR2 for your high pass filter.

4. I like the blue trace the best out of your models, cant tell which alignment it is.... I'm guessing the Beta 10 Sealed.

Thanks, Nick!

1. Ah, yes. Good point.
2. Lower in frequency or amplitude?
3. I just used the first available in the program for the sake of completeness. I don't have a choice with my AVR as to what crossover type it employs as part of the bass management DSP.
4. Yes, the dark trace is the Beta 10CX in a 0.5 ft^3 sealed enclosure, which is what I am building. wink.gif

Mike
post #692 of 863
The original sealed 10" design was in a box around .75cuft.
post #693 of 863
Quote:
Originally Posted by mhutchins View Post

Quote:
Originally Posted by NicksHitachi View Post

2. Lower in frequency or amplitude?

Frequency

3. I just used the first available in the program for the sake of completeness. I don't have a choice with my AVR as to what crossover type it employs as part of the bass management DSP.

Most conventional AVRs employ the THX strategy for bass management which is LR4 low pass and LR2 high pass. If your using the bass management of your AVR or other conventional consumer bass management equipment it prob is LR2 on the high pass. This can be important when modeling and assessing excursion as butterworth and LR differ considerably.

4. Yes, the dark trace is the Beta 10CX in a 0.5 ft^3 sealed enclosure, which is what I am building. wink.gif

I like that design too, If I were building out surrounds now, thats what I'd be popping on.

Mike

Shoot for a Qtc as reasonably close to .7(IDK what that is for this speaker) if you want to approximate THX stuff.
post #694 of 863
Quote:
Originally Posted by NicksHitachi View Post


2. I would personally like to see the port resonance a little lower out of the midrange but thats just me. I'm personally a fanboy of sealed for this an many other reasons.

OOPS, I miss-typed here.

Youll want the resonance as far away from the passband of the woofer as possible. IDK where the speaker is crossed over but with an enslosure that small your more likely to be able to push it above the passband of the woofer instead of below.
post #695 of 863
Quote:
Originally Posted by Erich H View Post

Today's project: Surround sound flat pack.

Here are some photos of a surround sound angled box. This is a prototype with the top about 9.75" deep, the bottom is 6" deep, and it's 14" wide. 3/4" MDF and very easy to assemble. I believe it's roughly a 16 degree angle. It could be made with .5" Baltic birch with a 3/4" baffle to save weight. But doing that might require a brace which is getting pretty tight.

I do need some input on the way the front baffle works out.




Here's the side view with the baffle on:




I only had a 1/2" roundover bit in my router, but it still looks okay on the top:




But because of the angle, the bottom looks a little 'off'. I think it might look just fine if it had used a full 3/4" roundover instead of the smaller one.






Even if that roundover doesn't match up 100% right, it still looks pretty good and you can't tell from the bottom, only the side. The other option (if the 3/4" bit doesn't work) would be to skip the roundover on the bottom, but then they'd have to miter it to make it perfectly flat on the bottom. Basically to miter the correct angle where the red line is in this photo:



If it's mitered flat on the bottom, maybe it should be done on the top as well? I like the roundover on the top and sides, so maybe a bigger roundover will fix the issue along the bottom edge. No clue right now, but it should work. Somehow I forgot to take photos of the front. rolleyes.gif


I took a different approach to accommodate Erich’s precut baffles that would allow a 90º side/baffle joint and therefore making it easier to adjust enclosure volume by simply lengthening the sides. This is necessary because each enclosure will have different angles so that it can be aimed at the primary listening position.

I’m assuming that enclosure volume is the main consideration and not shape. Is that true?

The rear enclosures will be recessed into the wall.

thatguytwc.com 88k .jpg file
post #696 of 863
Quote:
Originally Posted by Pan Head View Post

I took a different approach to accommodate Erich’s precut baffles that would allow a 90º side/baffle joint and therefore making it easier to adjust enclosure volume by simply lengthening the sides. This is necessary because each enclosure will have different angles so that it can be aimed at the primary listening position.

I’m assuming that enclosure volume is the main consideration and not shape. Is that true?

You don't necessarily want to aim them directly at the listening positions. In the horizontal plane, yes, but in the vertical plane, probably not. You probably want to aim for the head of the person sitting farthest away from any given surround. In this way, you have a chance of achieving some Time-Intensity-Trading to broaden the surround soundfield and decrease awareness of source localization.

In short, aim over their heads, not into the middle of the crowd.

Mike
post #697 of 863
Mike,

Thanks for your reply. That makes sense, especially in a larger room.

What about the shape of the enclosure--does it matter, or just the volume?
post #698 of 863
Are you guys okay with the 16 degree angle for the surround flat pack or would you rather have something else? I need to get this finalized so they can be cut.

Also, would you rather have them 3/4" mdf all around, or should we use 1/2" Baltic with some braces and a 3/4" front baffle.

The 1/2" Baltic might not be super smooth along the mitered angle like MDF would be because of it being plywood. But maybe it wouldn't be too bad.
post #699 of 863
I'm good with the 16 degree angle and would buy 4 of them if you need to gauge interest Erich. Are they going to be done in BB or MDF? My personal preference would be 0.5 baltic birch since it would have a little more internal volume for the same foot print and be lighter for wall mounting, but really I'm good with either material in the end. I'm sure you'll have a pile of interest in these.smile.gif
post #700 of 863
Quote:
Originally Posted by Erich H View Post

Are you guys okay with the 16 degree angle for the surround flat pack or would you rather have something else? I need to get this finalized so they can be cut.

Also, would you rather have them 3/4" mdf all around, or should we use 1/2" Baltic with some braces and a 3/4" front baffle.

The 1/2" Baltic might not be super smooth along the mitered angle like MDF would be because of it being plywood. But maybe it wouldn't be too bad.

1/2 Baltic would be really nice to use. I know for me I personally think that a 20degree option would be a lot better for guys that have rooms 13' feet and narrower.

16 degrees would be better for guys with much wider rooms, the back of my room where the seats are is 12ft wide. I just took out my iphone with the level app and 20 degrees would be perfectly spot on for surrounds.
post #701 of 863
I probably want four as well, and I think 16 degrees sounds right. I lean towards MDF for consistency in finishing, but nice plywood wouldn't keep me from buying.

Actually, I'd be very happy with just a baffle. Since I assume there won't be any built-in provision for mounting or anything, I might be happier just building from scratch. Obviously, others will want flat packs.
post #702 of 863
I would take 2
post #703 of 863
I will take 6. Another vote for MDF but I would buy birch also.
post #704 of 863

I would be interested in 4 to 6.

post #705 of 863
I would be up for 4 of them! I think that the 16 degree angle would be perfect for most folks, and yes, I understand that some folks may need more or less of an angle, but, I think 16 degrees is a good compromise.

For the wood, I would really like to see 1/2" birch with a 3/4" MDF baffle, for no other reason than weight savings. Most of us will be wall mounting these, so the lighter enclosures would be preferred!
post #706 of 863
Am I the only one that has a narrow room?... confused.gif LOL
post #707 of 863
You're not alone smile.gif 11.5' width in my theater.
post #708 of 863
I've measured it in my room a couple times, and I'm convinced that anyone with a room that's 13ft and narrower would be better off with a 20degree slant instead of a 16degree.
post #709 of 863
You're definitely not alone - if I had 16+ feet of width, I'd probably use an SEOS - but since I'm at 12' I need something more compact. Have you seen mhutchins' posts about his setup with V10s? http://www.avsforum.com/t/1498313/surround-speaker-design-for-a-small-home-theater/60#post_24279346
post #710 of 863
I vote for 20 degrees, but 16 degrees may present no practical difference.

Mike
post #711 of 863
Quote:
Originally Posted by jbrown15 View Post

I've measured it in my room a couple times, and I'm convinced that anyone with a room that's 13ft and narrower would be better off with a 20degree slant instead of a 16degree.

What height will speakers be off floor or riser? My room is 12 feet wide sides will be mounted at 7 1/2 feet off the floor to the top of speaker. My second row riser will be 12 to 14 inches above floor level (haven't built it yet) . To me I shouldn't need much angle to be on axis with speaker at the opposite side seat ?  The rears will be at 8 1/2 feet off floor to the tops and about 8 to 9 feet behind second row seating.  I'm thinking that I would want rears to just shoot over heads of rear row people so that they don't "block" the sound? 

post #712 of 863
Quote:
Originally Posted by jbrown15 View Post

Am I the only one that has a narrow room?... confused.gif LOL


Nope,  I think I get the prize for the narrowest room... 8ft

 

Erich put me down for 2 with a 20* slant....

post #713 of 863
Is it too much trouble to offer both 16* and 20*? Looks like there are half and half
post #714 of 863
I would shoot for 18 degrees and just cut it right down the middle. Does that make any sense to consider?
post #715 of 863
Quote:
Originally Posted by Erich H View Post

I would shoot for 18 degrees and just cut it right down the middle. Does that make any sense to consider?

I'd still prefer 20 degrees...lol
But you're the one calling the shots Erich smile.gif
post #716 of 863
Quote:
Originally Posted by Erich H View Post

I would shoot for 18 degrees and just cut it right down the middle. Does that make any sense to consider?

great compromise. when can we start ordering?
post #717 of 863
2 degrees would never be noticeable either way. I'm not sure if you guys are hoping these shoot right down on you or not, but I wouldn't want them doing that for surrounds. And i think coaxials are a little better slightly off axis aren't they?
post #718 of 863
Quote:
Originally Posted by Erich H View Post

2 degrees would never be noticeable either way. I'm not sure if you guys are hoping these shoot right down on you or not, but I wouldn't want them doing that for surrounds. And i think coaxials are a little better slightly off axis aren't they?

For me the 2 degrees is the difference of a left surround basically shooting over my center seat and basically aiming at the right seat. So my concern would be what is the person seating in that left seat missing out on. And the same would go for the right speaker being aimed right over the head of the center seat towards the left seating position.

But like I said before I might be in the minority and have a narrower room at 12ft wide.
post #719 of 863
In that case, it might be better to not use any angled box at all. I wouldn't want any of these aimed at my head in a small room. eek.gif
post #720 of 863
Quote:
Originally Posted by jbrown15 View Post

Quote:
Originally Posted by Erich H View Post

2 degrees would never be noticeable either way. I'm not sure if you guys are hoping these shoot right down on you or not, but I wouldn't want them doing that for surrounds. And i think coaxials are a little better slightly off axis aren't they?

For me the 2 degrees is the difference of a left surround basically shooting over my center seat and basically aiming at the right seat. So my concern would be what is the person seating in that left seat missing out on. And the same would go for the right speaker being aimed right over the head of the center seat towards the left seating position.

But like I said before I might be in the minority and have a narrower room at 12ft wide.

If you mount the 18* speaker lower , it would aim at the right seat. or tilt the top out a little to make up for the 2 degrees
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