# Tritrix towers



## lunchmoney

Here's the design for my new mains... they're four feet tall, and use dual Dayton 5.25 classics, and a Dayton silk dome tweeter... also going to be making a center channel with the exact same design (although not towers, and laid on its side... obviously).

It's based on the Tritrix design, found here...

http://www.geocities.com/cc00541/Tritrix_pg_1.html


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## ItalynStylion

Sexy looking....I like the rear portion. If it was me I might even make it a touch more pronounced. Are you going to leave the rears open like that or finish off the section some how? Kerfing?


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## lunchmoney

ItalynStylion said:


> Sexy looking....I like the rear portion. If it was me I might even make it a touch more pronounced. Are you going to leave the rears open like that or finish off the section some how? Kerfing?


Just gonna leave them open. Because of how they'll be positioned in the room, you'll never see them from behind... and I don't mind how they look from behind.... thought about kerfing some fdm to fill them, but it would be a LOT of work.


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## ItalynStylion

lunchmoney said:


> Just gonna leave them open. Because of how they'll be positioned in the room, you'll never see them from behind... and I don't mind how they look from behind.... thought about kerfing some fdm to fill them, but it would be a LOT of work.


Yeah, I know what you mean. I've got a single blade circular saw and a gave kerfing a quick try one day. I think I could do it well but it would be a serious ***** to really do anything with.


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## lunchmoney

My biggest concern right now is whether or not they'll be too top heavy and tippy... gotta figure out a way to put a VERY heavy weight in the bottom... wanna avoid any kind of larger base or outriggers, as that will ruin the design... the top heavy look is what makes it, IMO.


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## Ga foo 88

Out of curiosity why didn't you do the t-lines?


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## lunchmoney

Ga foo 88 said:


> Out of curiosity why didn't you do the t-lines?


These are going to be 90% for home theatre use, high passed and used with a sub... so the TL or vented versions wouldn't get me much.

I've been chatting with the designer of the Tritrix's, and he concurs.

Plus I really like the small footprint of the sealed enclosures, which makes the proportions of this design possible.


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## ItalynStylion

You could kerf a small section of the bottom making it like a little bowl and pour some concrete into it. That way you keep the same base geometry and you still get a lower center of gravity.


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## lunchmoney

ItalynStylion said:


> You could kerf a small section of the bottom making it like a little bowl and pour some concrete into it. That way you keep the same base geometry and you still get a lower center of gravity.


Or just raise a vertical wall (similar to your kerfing idea only easier)... probably just fill it with sand


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## ItalynStylion

lunchmoney said:


> Or just raise a vertical wall (similar to your kerfing idea only easier)... probably just fill it with sand


Yeah...the vertical wall would work well too but I wouldn't use sand. It could get messy


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## lunchmoney

The more I think about it, the more I think I should just avoid the problem altogether and design some minimal outriggers for them... make them nice and stable.


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## ItalynStylion

lunchmoney said:


> The more I think about it, the more I think I should just avoid the problem altogether and design some minimal outriggers for them... make them nice and stable.


Dude, no way. They are so clean and sleek the way they are. Keep them like that!


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## lunchmoney

ItalynStylion said:


> Dude, no way. They are so clean and sleek the way they are. Keep them like that!


sigh... yeah, you're right... I'm just worried that they're so tall and narrow that no matter how heavy I make the base, they'll still be tippy...

pondering...


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## bobditts

I sure wish I could see the pics here at work. I built a set of the tritrix towers and love them. Wish I had a way to run them active though. Cant wait to see what your design looks like.


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## lunchmoney

bobditts said:


> I sure wish I could see the pics here at work. I built a set of the tritrix towers and love them. Wish I had a way to run them active though. Cant wait to see what your design looks like.


Why do you want to go active with them?


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## bobditts

because I dont trust the passives I built lol


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## Griffith

Love the enclosure. Lunchmoney, you my friend just gave me an idea. However, I would use different drivers. I had a buddy that made a similar setup using the same tweeters, same drivers but the 6.5" version. He said the woofers were unimpressive.


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## lunchmoney

Griffith said:


> Love the enclosure. Lunchmoney, you my friend just gave me an idea. However, I would use different drivers. I had a buddy that made a similar setup using the same tweeters, same drivers but the 6.5" version. He said the woofers were unimpressive.


Thanks!

The Dayton drivers are used in a number of different speaker designs out there, with mixed results...

It's all in how well the crossovers and enclosures are designed... the Tritrix's are famous for sounding exceptional, and ridiculously good for the money, due to excellent crossover and enclosure design.


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## Tommythecat

lunchmoney said:


> the Tritrix's are famous for sounding exceptional...due to excellent...enclosure design.


Who actually believes this? From what I saw there was no design to the enclosure at all.


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## lunchmoney

Tommythecat said:


> Who actually believes this? From what I saw there was no design to the enclosure at all.


???

Ummm.... width, height, depth, driver location... these are are elements of the enclosure design, which have been specifically determined for this speaker... it's not a generic cabinet design... and this particular design is well known for being done very well.... 

Perhaps "well engineered" would be more accurate than "well designed"... there were functional parameters that were well determined for this setup.


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## DS-21

Either build your center exactly the same as your L and R, or skip it. Little ruins an otherwise competent system faster than that infernal hack the toppled-MTM.


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## tyroneshoes

DS-21 said:


> Either build your center exactly the same as your L and R, or skip it. Little ruins an otherwise competent system faster than that infernal hack the toppled-MTM.


Enlcosures look great.

Sorry to post jack but I have a question thats sorta relevant.

I have been working on plans for a center channel upgrade and I have a 2.5 way design with the rs125 and seas 29taf alum dome

Now I know a 2.5 is supposed to help with the issues brought up with horizontal mtm center image problems but I plan to spend lots of time on the project and want it done right.

DS21, would I be better off using a center channel thats a pointsource driver? Can you link to a good design I can work off of?

I dont have the height as my tv is wall mounted which gives me 12" of height.

Front speakers are rs180 and seas 29tafs as seen here.










Ill be doing floorstanders for the mains and want a center than can keep up.


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## lunchmoney

DS-21 said:


> Either build your center exactly the same as your L and R, or skip it. Little ruins an otherwise competent system faster than that infernal hack the toppled-MTM.


As stated in the OP, I will be making an identical center channel (laid on its side, not a tower, obviously)... this design is known for being a good center channel... the way that the drivers are located close together, along with some aspects of the x-over design, helps alleviate the off-axis deficiencies that plague most MTM's when used as center channels... the Tritrix was specifically designed to be used both as mains and a center, and even surrounds... that's why I went with this design, because I want the mains and center to be identical... also 'cuz I'm on a budget.

Not sure what you mean by "little ruins an otherwise competent system"... are you saying that a system can't sound good with small drivers? If so, I don't buy that for a second... particularly since I'm using a sub with them. Perhaps that's not what you meant.


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## lunchmoney

Tyrone...

See my post above about how the Tritrix is known for being a good MTM center channel... might be a good choice for you... particularly if you're on a budget, although it looks like you're thinking a bit more high end.


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## DS-21

tyroneshoes said:


> DS21, would I be better off using a center channel thats a pointsource driver? Can you link to a good design I can work off of?


Yes. But only if your mains speakers are thusly upgraded as well. Otherwise, build another one of your mains. The center should be exactly the same as the L and R, just as the L and R should be the same. And it should be at the same height, too.[/QUOTE]



lunchmoney said:


> As stated in the OP, I will be making an identical center channel (laid on its side, not a tower, obviously)... this design is known for being a good center channel...


There is no such thing as a good toppled-MTM. There are only varying degrees of ****ty. 



lunchmoney said:


> that's why I went with this design, because I want the mains and center to be identical... also 'cuz I'm on a budget.


I applaud that notion. You should make them identical, not just the same drivers with the worst possible topology for the most important speaker.



lunchmoney said:


> Not sure what you mean by "little ruins an otherwise competent system"...


It's pretty obvious: toppled-MTM's have _absolutely no place_ in any system with any claims to high fidelity.

I'm not going to knock someone for not being able to afford bigger/better drivers, but taking the parts you have and employing them in the worst possible way, that's different.


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## lunchmoney

DS-21 said:


> Yes. But only if your mains speakers are thusly upgraded as well. Otherwise, build another one of your mains. The center should be exactly the same as the L and R, just as the L and R should be the same. And it should be at the same height, too.
> 
> There is no such thing as a good toppled-MTM. There are only varying degrees of ****ty.
> 
> I applaud that notion. You should make them identical, not just the same drivers with the worst possible topology for the most important speaker.
> 
> It's pretty obvious: toppled-MTM's have _absolutely no place_ in any system with any claims to high fidelity.
> 
> I'm not going to knock someone for not being able to afford bigger/better drivers, but taking the parts you have and employing them in the worst possible way, that's different.


Please take no offense, but this post smacks of high-end snobbery.

How "****ty" something is is relative to your standards.

No matter how much you spend, or how good your speakers are, there will always be someone who calls the setup ****ty because they have better and spent more.

I'm sure your system is quite nice, and far better than what I'm planning here... but is a complete stinking heap of dogshit compared to someone else's system, because they spent twice as much.

I already have an MTM center, and I don't consider it to be "****ty" at all... just not as good as I would like. Given my space and budget constraints, making 3 Tritrix's makes a lot of sense, and I'm sure I'll be thrilled with it compared to what I have now. If you have a suggestion for a better-sounding system I can build for similar cost, I'd love to hear it.


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## lunchmoney

Further development... with center channel and bases for the towers... 

I decided that the towers were going to definitely be too top-heavy, even with a sand-filled chamber in the bottom, so I added a base to them... the extra slabs of 1" mdf in the base (shown in the 3rd picture in black) are simply to add weight... the upper most slab (shown wood-colored) is going to be doweled to the side walls of the tower for strength.... a big 'ol lag bolt through the middle of these slabs will fix the tower to the base.

The center channel is as large as it is in order to work well with the TV stand (the TV is going to sit directly on top of it)... the center channel has internal walls to create a sealed 7 liter enclosure, to match the towers... 

Not sure what color I'm going to paint them yet... gotta consult with my better half on that one.


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## DS-21

lunchmoney said:


> Please take no offense, but this post smacks of high-end snobbery.


Or a basic understanding of physics. A toppled-MTM is the single worst possible center channel configuration.

And it's not a matter of comparing systems. On an absolute level, toppled-MTM center channels all suck. Full stop. 



lunchmoney said:


> I'm sure your system is quite nice, and far better than what I'm planning here... but is a complete stinking heap of dogshit compared to someone else's system, because they spent twice as much.


Actually, probably not. Sure, I've spent a fair amount on my system, but the key is to spend money _intelligently._ One could easily spend $100k more and end up with massively inferior results. 



lunchmoney said:


> If you have a suggestion for a better-sounding system I can build for similar cost, I'd love to hear it.


I already gave you one, with not similar but identical cost: build three of those speakers, in identical configurations. Anything less is simply a waste of parts, time, and money. Alternately, save money, parts, and time by skipping the center entirely. You'd be better off with no center at all than a worthless toppled-MTM.


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## lunchmoney

Thanks... but I don't understand how I'm supposed to use a third tower as the center... that's where my rather large TV is... and sorry, but I just don't buy that no center is better than an MTM center.

Your opinion on MTM centers, valid though it is, is far and away the most extreme I've heard... most everyone says they're "less than ideal, but just fine if your sitting position isn't too far off axis"... which it isn't... you're the first I've heard to say that they suck outright... which I simply don't agree with, from experience, since I have one and have been enjoying it for years.

Anyways, opinion noted. Thanks for your input!


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## ItalynStylion

DS-21 said:


> I already gave you one, with not similar but identical cost: build three of those speakers, in identical configurations. Anything less is simply a waste of parts, time, and money. Alternately, save money, parts, and time by skipping the center entirely. You'd be better off with no center at all than a worthless toppled-MTM.


That would be nuts....how on earth would you implicate a center like that in a real world setup? Your TV would have to be like 6 feet off the ground. While I do agree that it is optimal, it's just not practical.


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## lunchmoney

Italyn, those stands I added workin' for ya? I think they look all right... I partucularly like the color break that matches the speakers... should make these things quite a bit more stable... still trying to figure out how to make them really HEAVY... I wish I could get 'em in cast iron or something... probably sink a 1/2" slab of steel into 'em.


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## lunchmoney

Autiophile said:


> Use an acoustically transparent screen and a projector...


lol... oh, is that all I have to do... well, not really an option... thanks though


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## lunchmoney

DS-21, you might be interested in this thread on the Parts Express forum...

According to this thread, and many others I've seen, there are a lot of people hallucinating how good their MTM centers sound... either that or they all must enjoy ****ty sound 

http://techtalk.parts-express.com/showthread.php?t=206004


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## ErinH

toppled mtm is bad?... hmmm.

*stores in brain for future use*


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## lunchmoney

bikinpunk said:


> toppled mtm is bad?... hmmm.
> 
> *stores in brain for future use*


not according to most... less than ideal perhaps...


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## DS-21

lunchmoney said:


> Thanks... but I don't understand how I'm supposed to use a third tower as the center... that's where my rather large TV is... and sorry, but I just don't buy that no center is better than an MTM center.


Well, I manage to have a 46" LCD screen and three identical main channels at the same elevation. So certainly it can be done. (The screen's stand sits about 20" off the ground. The speakers are all high; the apex of the 12" Dual Concentric drivers are all ~50" off the ground.)



lunchmoney said:


> Your opinion on MTM centers, valid though it is, is far and away the most extreme I've heard... most everyone says they're "less than ideal, but just fine if your sitting position isn't too far off axis"... which it isn't...


There are lots of people who don't understand power response or its implication on in-room response. They'll often bring up stuff about "lobing" that's not terribly relevant to in-room response except in an anechoic chamber. Furthermore, most people have not heard a properly implemented 3-channel front stage. After all, most centers (commercial and DIY) are unlistenable.



lunchmoney said:


> DS-21, you might be interested in this thread on the Parts Express forum...


Let's see. There's Bill Fitzmaurice and Zaph trying not to hurt your feelings by damning toppled-MTM's with faint praise, with the most revealing line being this one by Zaph: *"Horizontal MTM's are half of the reason dialog in movies is often described as hard to hear.*" (Note that he doesn't even _touch_ the issue of music, which is a pity because a well-implemented 3-channel front stage provides huge benefits in terms of soundstage width, breadth, and texture; I only listen to two-channel in the car now. Even my nearfield setup is three-channel.) And then people without measurement gear are saying they sound fine. You'll also find staunch advocates for Bose, somewhere, I'm sure.

I mean, do what you want, but some of us like to use our experience to prevent others from making mistakes we made when we were new at this whole audio thing....

Oh, and the drivers are not that close together. Their _frames_ may be, but the center-to-center distance is still quite significant.

(You may also wish to read this article, which is quite good except that his ultimate recommendation leads to unacceptable levels of midrange dynamic compression for my tastes.)


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## lunchmoney

DS-21 said:


> And then people without measurement gear are saying they sound fine.


And there's the difference... personally, I hope I never require equipment to tell me whether or not I enjoy how something sounds... that would suck... 

And I hope I never reach a level of standards whereby I'm so accustomed to things sounding 99 or 100 percent, that if they sound 95 percent I perceive them as 20 percent and lunge for my earplugs. 

As I said before, it comes down to a difference of standards.

Again, thanks for all your input. Much respect.


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## lunchmoney

Oh, and thanks for the link to that article... very good read...

And yet it hasn't swayed me from my plan to use the MTM center... that article clearly speaks to those with much higher standards than mine...

The irony is that as I was reading it, I was actually sitting in front of my TV with my laptop, half watching and listening to a movie on TV that's coming in in surround... as I'm reading about how wretched my center channel is, I'm listening to it and thinking "meh... sounds ok to me, glad I don't know enough to hate it" 

Standards.


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## ErinH

Seriously, until this thread I had never heard of a standing mtm as a center. It was always the traditional horizontal (toppled) set that was being used by tons of avid DIY'rs. But, after doing some research on DIYaudio it seems that DS-21 isn't the only one saying that toppled MTM centers are bad. So, thanks DS-21 for that interesting insight. I'll definitely keep what I'm reading in mind when it comes time to build my own setup.


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## squeak9798

bikinpunk said:


> Seriously, until this thread I had never heard of a standing mtm as a center. It was always the traditional horizontal (toppled) set that was being used by tons of avid DIY'rs. But, after doing some research on DIYaudio it seems that DS-21 isn't the only one saying that toppled MTM centers are bad. So, thanks DS-21 for that interesting insight. I'll definitely keep what I'm reading in mind when it comes time to build my own setup.


Yeah....the only reason horizontal MTM's are used is aesthetics. In LSDC Vance Dickason politely berates the alignment. His measurements clearly demonstrate the inferiority of the horizontal MTM....at one point resulting in a -25db dip @ 30 degrees off axis. The are ways to mitigate the deficiencies (angled baffles, for example)....but none that will result in same performance of a vertical MTM.

If I ever get off my ass and build my HT speakers, my original plan was to use a horizontal MTM. After reading LSDC and other resources, I'm now trying to devise a plan to keep all as identical vertical MTM's.


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## lunchmoney

A horizontal MTM center is very convenient... and works well when your desire for convenience outweighs your desire for perfection... is it an optimal configuration? No. Certainly not.

Back to my original plan... the whole point behind what I'm doing here is to have 3 identical speakers, with one of them "toppled" to fit under my TV... Curt Campbell specifically designed the Tritrix as a budget speaker to be used as both mains and a center, paying a lot of attention to designing it such that the inherent deficiencies of using an MTM as a center channel are minimized... and by all accounts he did a remarkable job of it... so for my needs it's a great solution.


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## ErinH

I'd like to see pictures of how people are incorporating a vertical mtm center into their systems... in instances where the center is not hidden by a screen. In other words, a 'normal' setup.


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## lunchmoney

Here is the updated design.

I decided to go vented, with an internal volume of 22.3 liters... drivers, port, crossover, and foam lining volumes have not been subtracted from this volume... crossover not shown, yes it will be inside the enclosure (haven't decided where yet). 

The curved back walls will be an adventure in kerfing and bondo


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## ErinH

Do you have the x-over design yet?

Curious how you're coming up with this design. Is it a pre-made design, are you doing this from scratch, etc?... looks good.

Nice cad work. I need to freshen up my skillz.


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## lunchmoney

Thanks punk... it's based on Curt Campbell's Tritrix design, located here:

http://www.geocities.com/cc00541/Tritrix_pg_1.html

Driver selection, placement, baffle width, internal volume, and crossover design are exactly to Curt's spec (all info on that site I posted above)... 

Other than that the design is pure lunchmoney


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## ItalynStylion

Lunch, that is going to be sooo pimp! I think you will be much happier with the end result. It will be a lot of work but it will be worth it!


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## lunchmoney

After some input from the guys at htguide.com and the parts express forum, the conclusion was that it was too shallow and tall, and would be suffering from bad reflections off the rear wall as well as resonance issues...

So I'm giving up on the low profile shallow depth look... form must be simultaneous to function... (NOT "follow" function... don't get me started)

Volume is still 22 liters... center line of the elbow port is 5" long... I've put in a barrier of 1.5" thick foam behind the drivers and port, to separate the drivers and port from the stuffing.

Back panel will be 3 laminated layers of 1/4" masonite.


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## ItalynStylion

Will the stuffing still make a substantial effect considering it's not in the open area that the port and the rear of the speakers is in? That's an honest question I have no idea and would like to know.


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## lunchmoney

The barrier behind the drivers is open-celled foam, so it's almost as though there's no barrier there at all... so yes, the stuffing is still effective and important.


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## lunchmoney

Ok... here it is... final design... gonna start making dust friday afternoon.

Curt Campbell (the designer of the Tritrix, on which this is based) gave the previous iteration a thumbs up, with a slight change that I might want to put the vent in the back... I initially thought I liked the look of the port on the front, but have changed my mind in favor of a cleaner look on the front... 

...besides, an internal support for the rear-mounted port also becomes a convenient location for an internal brace for the entire enclosure.

Still 22 liters... 22.3 to be precise (with all of Tritrix Curt's enclosure designs, he seemed to add about .3 liters to the designated volume, so I figured I would follow suit)

Dimensions are slightly tweaked from the previous design which Curt ok'd... but if the previous dim's were ok and these dim's aren't, then we're firmly in the territory of differences that I would never notice 

I'll be starting a build log thread when I start building them.


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## DS-21

lunchmoney said:


> Back to my original plan... the whole point behind what I'm doing here is to have 3 identical speakers, with one of them "toppled" to fit under my TV...


Of course, then you don't have three _identical_ speakers. You just have three speakers using the same drivers and crossover design, with one of them being entirely different in radiation pattern and performance from the other two.



bikinpunk said:


> I'd like to see pictures of how people are incorporating a vertical mtm center into their systems... in instances where the center is not hidden by a screen. In other words, a 'normal' setup.


While a 12" coax rather than an MTM, here's how I do it.









For size reference, the screen is a 46" LCD, and subwoofer pictured uses an 18" Exodus Maelstrom-X.

(And no, I can't take pictures worth a damn. Sorry.)


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## DaveRulz

There is one change I would make to the plan you have laid out there. Since you plan on kerf cutting the back, it would be in your best interest to make the sides overlap the rear piece rather than vice versa. That way all of your kerfs are contained between the two side pieces lessening the chances of leaks. 

Just the way I would do it from woodworking standpoint. 

Dave


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## lunchmoney

Thanks DS... safe to say that putting a speaker above my TV in this manner would never fly.

Curt is going to be designing a crossover for a "fat Tritrix center"... the baffle will be wider (or shorter, I should say, since it's toppled), so that the tweeter can be offset more, and the mids closer together...

so no, all 3 won't be identical, but at least they'll have the same drivers, and very similar crossovers, all designed by the same dude.

I'm sure the system will be more than adequate for my standards.


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## lunchmoney

DaveRulz said:


> There is one change I would make to the plan you have laid out there. Since you plan on kerf cutting the back, it would be in your best interest to make the sides overlap the rear piece rather than vice versa. That way all of your kerfs are contained between the two side pieces lessening the chances of leaks.
> 
> Just the way I would do it from woodworking standpoint.
> 
> Dave


Thanks Dave... I'm actually going to be laminating 3 layers of 1/4" masonite instead of kerfing... thus it's going to be easier to have them lay over the side walls.


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## backwoods

squeak9798 said:


> His measurements clearly demonstrate the inferiority of the horizontal MTM....at one point resulting in a -25db dip @ 30 degrees off axis. .


Most of the problems with mtm is off the shelf designs. Many of the deficencies can be overcome with "in place" design. People forget how much the location of the horizontal mtm is affected by whether it is located above/below the tv, near the wall or on a table. 

Also, as far as the off axis response, that isn't nearly as critical in a center channel assuming you are "near" the center of the room and being nearly on axis with the driver.

Also, the tritrix is a very nice design, but for predesigned systems, zaphs' zdt3.5 really blows it away in every aspect and is definitly worth the extra dough. The crossover design is much more thorough imo, and the drivers are much nicer.

The classic drivers are solid drivers, but there are others I would consider at that price point. 

your design looks visually impressive, but the tweeter suffers a mild breakup near 2k that I could identify when listening and the woofers are somewhat "edgy" in guitars and other stringed instruments. 

I'm sure you will like for the cost, but as far as performance improvement over the br-1 kit with upgraded crossovers, not sure it's worth it, unless you are in a larger room and need the added spl of a secondary woofer in each location.

I can obtain 105 db in a 20x12 room using a 5.1 br-1 setup. (105 I believe is the thx standard). Which, is plenty loud.

Just some more tidbits to consider... 

If you want to have fun on a budget, build an mtm design using the hivi drivers and a dedicated sub. Definitly blow you away and can be done (including the sub and all 5 channels) for under $500.


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## ErinH

backwoods said:


> Also, the tritrix is a very nice design, but for predesigned systems, zaphs' zdt3.5 really blows it away in every aspect and is definitly worth the extra dough. The crossover design is much more thorough imo, and the drivers are much nicer.


speaking of which... didn't you say you built some yourself? Where are the pictures?


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## backwoods

bikinpunk said:


> speaking of which... didn't you say you built some yourself? Where are the pictures?


I did build a set, and sold them.

I have another set built, but have been waiting on a couple parts for the xover to come back in stock. Once I get them, I'm gonna do some simple build pics on the xovers.


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## ErinH

Heck, I'd take pics of what you've got going so far.


I'm pretty sure I'll do a DIY on my fronts and center, but I'll be using my aperions on the side surrounds. I'd like to do a scan setup in the front, but I don't know if my budget would allow. Even at used/dealer prices.


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## DaveRulz

lunchmoney said:


> Thanks Dave... I'm actually going to be laminating 3 layers of 1/4" masonite instead of kerfing... thus it's going to be easier to have them lay over the side walls.


That's a much better method! Then you don't have to deal with filling in all of those kerfs. I've used this method before for making curves. Comes out rock solid. 3 layers is probably actually overkill as the curve itself will strengthen it.


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## backwoods

bikinpunk said:


> Heck, I'd take pics of what you've got going so far.
> 
> 
> I'm pretty sure I'll do a DIY on my fronts and center, but I'll be using my aperions on the side surrounds. I'd like to do a scan setup in the front, but I don't know if my budget would allow. Even at used/dealer prices.


can do..

and I promised some photos of a new HT with everything in wall as well.. 

Should be pretty sweet. All drivers in wall and a couple 15's ib all in a small room. The owner is partly deaf and wanted something LOUD...


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## DS-21

backwoods said:


> Most of the problems with mtm is off the shelf designs.


Not really. The problems are inherent to the power response of the topology: wide-open vertical directivity to ensure the maximum possible amount of smearing reflections from the floor and ceiling, and narrow horizontal directivity with massive midband flaws caused by comb filtering. 

One can certainly futz around the margins and get something marginally less worthless, but doesn't it seem far smarter to simply start with a less flawed basic design?



backwoods said:


> Also, as far as the off axis response, that isn't nearly as critical in a center channel assuming you are "near" the center of the room and being nearly on axis with the driver.


That's wrong for two reasons.
First, the ragged off-axis midband response of every toppled MTM certainly shows up in the response at the listening position, even if one's directly on-axis. The "lobing" argument is bunk. (Unless one's room is an anechoic chamber.)
Second, the main point of a discrete center is, after all, to enlarge the listening area. Stereo does pretty well for "near the center of the room and being nearly on axis." A center channel with poorly controlled directivity and narrow dispersion is, then, the exact opposite of what one should want in a center.


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## backwoods

DS, nobody is trying to argue that lobing is not a serious issue with horizontal mtm designs, but I was stating that it can be defused to a useable level with a solid crossover design. 

Also, even if you go with a -25db dip at 30 degrees, with an 8' listening distance, 30 degrees gives you 4.5' on each side of center axis. 

Yes, one big benefit of center channel is enlarging the listening distance, but I do not use surround for music, really only movies, where perfect FR off axis is not required.

and a simple 6" tall MTM is a helluva lot easire to make part of a room then a vertical MTM or even a simple TM design (which is what I suggested if the room is not bigger then 20x12)

(irony of this is I am looking at coaxials right now for the inwall design)


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## backwoods

one last thing, benefit of the zdt3.5 is your center channel arrangement is a wmtw, and I'd assume zaph will make the tm vertical.

That'd even make DS happy!


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## DS-21

backwoods said:


> one last thing, benefit of the zdt3.5 is your center channel arrangement is a wmtw, and I'd assume zaph will make the tm vertical.
> 
> That'd even make DS happy!


Only if all three speakers use that same driver topology, and are arrayed at the same elevation, on stands with similar acoustic shadows, preferably on the exact same stands. (Yes, I'm saying use speakers that are considerably wider than they are tall for all three channels, if one's center has that restriction.) 

And I disagree with you that it is at all possible to make a toppled-MTM sound acceptable in anything save an extreme nearfield setup (where the effective response at one's ears is the on-axis response) or if one's room is an anechoic chamber. In any other setting, I submit that it's far better to forgo the center entirely than use such a bad-sounding hack.

You bring up the bunk "lobing" argument I mentioned. At the listening position in a normal room, the on-axis sound is not what dominates. The total power response of the speaker does. Toppled-MTM's by definition have crappy midband power response, which is why they always sound so bad. Admittedly, I'm probably 95% music I care about/5% visuals I care about (and that pretty much only during football season, really; who really cares about sonic fidelity for the Daily Show or Fareed Zakaria GPS?) so people who are more into the picture side of things may well have relaxed standards for audio fidelity. But the severe midband power response problems inherent to the toppled-MTM, as Zaph mentioned in his PE post linked above, are also the reason why TV/movie dialogue is often so unintelligible on home theater systems...


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## backwoods

DS-21 said:


> Only if all three speakers use that same driver topology, and are arrayed at the same elevation, on stands with similar acoustic shadows, preferably on the exact same stands. (Yes, I'm saying use speakers that are considerably wider than they are tall for all three channels, if one's center has that restriction.)
> ...


hmm, interesting. personally, I have not found much difference in fr from speakers having minor differences in elevation. In fact, I don't think I have found where it affected total power response/fr from the drivers as long as the change did not affect baffle size or place it behind a chair/couch.

My HT last winter was fully active, and at one point used a "toppled" mtm with very solid results. No problems understanding dialogue, and most often was left on for all shows because of the improved clairity. I used a 500hz lp on one mid to avoid midrange issues and worked out great.

I find it interesting that you combated this with coaxial drivers, ime I have had to high pass them close to 200hz to avoid audible distortion in the upper frequencies, which then can move important fundemental tones to the subs, causing serious presence issues. Now somewhere I read the suggestion (may have been on zaphs site) of using a sub in each corner to help combat that phenominon. (I think he was referring to using them for fullrange drivers) but is an answer I am considering for my next coax design.

But, I am hoping that by using the coaxs in wall, it will improve low end response on the drivers by increasing baffle size, helping to limit required excursion to reduce distortion on the tweeter and still cross them low enough to make worthwhile. 

(it'll be an expensive experiment)

I wish I still had some of those "toppled" mtm's handy to take some off axis measurements for you.


by the way, in any situation, I would argue for a simple vertical tm to be used on all channels just to avoid the grief, unless it is for a large room.


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## ErinH

Backwoods, you keep talking, but I haven't seen any pictures yet!..


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## br85

I would also like to see pics.


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## backwoods

haha, bad week to do it. Been remodeling my house.

Sunday I'll get you pics of some towers and a neat use for some old IDQ's in an HT..


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## DS-21

backwoods said:


> I find it interesting that you combated this with coaxial drivers, ime I have had to high pass them close to 200hz to avoid audible distortion in the upper frequencies, which then can move important fundemental tones to the subs, causing serious presence issues.


Keep in mind that the coaxes I use are 12" and 96 dB/w/m. So even at ear-bleeding levels they don't move enough to worry about, despite the fact that I'm running them full-range. (I was convinced to try that approach by posts on various fora by Dr. Geddes and Chris Kyriakakis of Audyssey, and I definitely get smoother response in the upper bass in my room doing things that way, with no notable loss of dynamics.)

Another approach is to use a smaller coax with midbass augmentation. That's the approach used by the Gradient Revolution (bespoke 7" Seas coax with aluminum tweeter and my favorite Seas cone, the "G" model, along with large woofers) and various speakers by KEF and TAD, among others.



backwoods said:


> Now somewhere I read the suggestion (may have been on zaphs site) of using a sub in each corner to help combat that phenominon. (I think he was referring to using them for fullrange drivers) but is an answer I am considering for my next coax design.


I've found Geddes' approach to subwoofer placement (three subs, one in the "best" corner for ULF, two randomly in the room but as far away from one another as possible, with one mounted above the room's vertical centerline) to result in extraordinarily smooth bass response and superior image size even with rather high sub hi-pass filters (like 125Hz).



backwoods said:


> by the way, in any situation, I would argue for a simple vertical tm to be used on all channels just to avoid the grief, unless it is for a large room.


That's the Tom Nousaine argument, and it makes some sense. It only fails in that a standard MT with the tweeter on a 180deg waveguide (i.e. flush on the baffle) will have pretty nasty power response issues in the midrange due to the wide-open tweeter directivity and narrow woofer directivity in the passband. Once one's heard how much more like real music a speaker with controlled and constant midband directivity sounds, I can't fathom why one would desire a return to lesser implementations.


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## backwoods

DS-21 said:


> Keep in mind that the coaxes I use are 12" and 96 dB/w/m. So even at ear-bleeding levels they don't move enough to worry about, despite the fact that I'm running them full-range. (I was convinced to try that approach by posts on various fora by Dr. Geddes and Chris Kyriakakis of Audyssey, and I definitely get smoother response in the upper bass in my room doing things that way, with no notable loss of dynamics.)
> 
> Another approach is to use a smaller coax with midbass augmentation. That's the approach used by the Gradient Revolution (bespoke 7" Seas coax with aluminum tweeter and my favorite Seas cone, the "G" model, along with large woofers) and various speakers by KEF and TAD, among others.


It's a give or take situation. Either increase cone area or raise the hp. Many rooms, a 12" coax is very difficult. I'm hoping a very large baffle will help me find a happy medium.




> I've found Geddes' approach to subwoofer placement (three subs, one in the "best" corner for ULF, two randomly in the room but as far away from one another as possible, with one mounted above the room's vertical centerline) to result in extraordinarily smooth bass response and superior image size even with rather high sub hi-pass filters (like 125Hz).


In essence the "excite as many room nodes as possible" approach.. I've always been curious of the outcome, but once again, a difficult implementation. I'd love to have some first hand experience.



> That's the Tom Nousaine argument, and it makes some sense. It only fails in that a standard MT with the tweeter on a 180deg waveguide (i.e. flush on the baffle) will have pretty nasty power response issues in the midrange due to the wide-open tweeter directivity and narrow woofer directivity in the passband. Once one's heard how much more like real music a speaker with controlled and constant midband directivity sounds, I can't fathom why one would desire a return to lesser implementations.


It's very difficult to return from the orion for much of those reasons. We call it "putting the music back in the box". 

I do agree that controlled midband directivity does allow for the most lifelike and realistic experience, but is much harder to achieve in smaller rooms.


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## DS-21

backwoods said:


> In essence the "excite as many room nodes as possible" approach.. I've always been curious of the outcome, but once again, a difficult implementation. I'd love to have some first hand experience.


It's not really that difficult, as long as you have phase adjustments on all one's sub amps. True, integrating the subs aesthetically into the room can be a problem, especially if one's relying on off-the-peg subs instead of making them or getting them made.



backwoods said:


> It's very difficult to return from the orion for much of those reasons. We call it "putting the music back in the box".


I didn't realize you were rocking Orions. I've never heard them, though I did spend a fair amount of very pleasant time in front of a pair of SL's earlier Audio Artistry Dvorak design when I lived in Vienna. I'd like to hear them sometime.



backwoods said:


> I do agree that controlled midband directivity does allow for the most lifelike and realistic experience, but is much harder to achieve in smaller rooms.


Controlled and narrow directivity is the only way to get good sound in a smaller room, IMO. Take the side walls out of the equation as much as possible. Omnidirectionality also makes about as much theoretical sense and lots of people who have heard good omni setups rave about them, but sonically I've never personally found an omni speaker satisfying. And then there's the kludge of omni bass, narrowing lower midrange, flares in the mids, and narrowing treble that is the typical "hi-fi" speaker....


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## backwoods

I agree it is the best bet for a small room, but most of the time, it requires good seperation from the walls to achieve. If you have a 20x12 room, then it is hard to pull speakers atleast 2' from each wall to decouple and cause the desired effect, causing a drastic reduction in useable floor space. 

Now, if it is JUST a listening room, then that is feasible, but so many still want to put it in the living room as well.

Orions are nearly perfect. But, suffers the same downfalls as many controlled directivity setups, choral music and other large presence recordings suffer in comparison to a nice omnidirectional setup (that's the only situation I have heard where I really enjoyed the omni's).

Quick question, on your coax setup, does it use any type of waveguide for the tweeter? And do you see any movement of the guide during heavy excursion?

I'm trying to decide right now to go the coax route or to do a simple mtm and playing with the new seas 27tbcd tweeter.


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## DS-21

backwoods said:


> I agree it is the best bet for a small room, but most of the time, it requires good seperation from the walls to achieve.


That's one of the beauties of controlled directivity monopoles: you get the bass benefits of boundary-loading, without the nasty mid/treble diffraction effects. My 12 DMT II's are all against the wall, and the left one is even in a corner. With the bass properly adjusted for distance, they don't fare any worse in the corners, and look a whole lot better than a bunch of damn speakers out in the middle of the room. 



backwoods said:


> Orions are nearly perfect. But, suffers the same downfalls as many controlled directivity setups, choral music and other large presence recordings suffer in comparison to a nice omnidirectional setup (that's the only situation I have heard where I really enjoyed the omni's).


Hmm. I wonder if that's a cone area issue. I've never heard a better system design for large-scale orchestral works (I don't listen to choral stuff much, but lots of Shostakovich, Mahler, etc.) than controlled-directivity speakers, be they coaxes or separate drivers with big waveguides and big woofers. A single Excel 8 for the lower mids isn't much, especially considering it's out in the open. 



backwoods said:


> Quick question, on your coax setup, does it use any type of waveguide for the tweeter? And do you see any movement of the guide during heavy excursion?


The Tannoy DC uses a phase plug/waveguide made out of concentric tubular extrusions, and then the rest of the waveguide is the profile of the cone. 

See more about the basic design here: http://audioloft.com/WPDualConcentrics.pdf
(They differ from the B&C, BMS, Beyma, Radian, Eminence, etc. coaxes in that those typically just have short conical throat bored through the polepiece. I've certainly heard that type of design sound great, too, especially the B&C ones.)

On the 12"s, even playing Shostakovich 7 full tilt, or blasting Radiohead, the drivers only visible move in the bass, and I can't really "hear" their movement. The 8's in my nearfield setup, with a 100Hz, 12dB/oct crossover and a W15GTi under them, don't visibly move at all at any level I can stand to hear from ~4' away.



backwoods said:


> I'm trying to decide right now to go the coax route or to do a simple mtm and playing with the new seas 27tbcd tweeter.


That's the one on the diffraction waveguide, right? Either way might be interesting. I would probably do both (WCW layout) if I couldn't fit a 10" or bigger coax.


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## backwoods

yep, it's the seas with the small waveguide.

Where did you get raw tannoy drivers? I'd love to get a line on them.


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## DS-21

backwoods said:


> Where did you get raw tannoy drivers? I'd love to get a line on them.


I didn't get raw drivers, I bought whole speakers locally and on eBay. I'm currently running three 12 DMT II's in the main system, though Nathan Funk is building me new cabs to replace the ugly Tannoy ones. In the nearfield system, two of the speakers are unmodified System 8 NFM II's, and the center channel is a Saturn S8iw in-wall model - same Dual as the 8 NFM II - and modified the crossover.

You can find good deals on Tannoy studio monitors on eBay. For example, here's a pair of 12 DMT II's for reasonable money, and here's a pair of 10 DMT II's for peanuts.


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## backwoods

pics will be a few more days... Too many projects still going in the house...


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## DS-21

Autiophile said:


> How did you implement the "above vertical centerline" subwoofer? I'm going to try Geddes' approach and I've got placement of the ULF and one of the other subwoofers figured out, but getting the third above the room centerline is giving me fits.


I did one next to a bookshelf, in the same material and at the same depth. So it's a tall, shallow sub with the driver mounted on the top section, facing out. It's pretty unobtrusive.

(All my subs right now are sealed, not BP. I am thinking of trying BP subs for the non-corner ones, using XLS12's currently in my closet. The ULF sub will remain the excellent Maelstrom-X in a sealed box.)


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## ErinH

^ Do you have any pictures of your setup, or a build log?


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## [email protected]

DS-21 said:


> While a 12" coax rather than an MTM, here's how I do it.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> QUOTE]
> 
> 
> that looks like crap,


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## backwoods

Autiophile said:


> Way to miss the point.


not totally. 

Part of the argument has been about aesthetics, and most of the installs done around that style do look like crap. Costs big bucks to do many of those things we ahve discussed and get it to look nice.


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## backwoods

nope, you missed more of the point. The speaker sitting on top of the tv has a direct affect on the size of the baffle, and a big part of the discussion is why some go with a toppled mtm in spite of it's problems for the aesthetic reasons, in which I mentioned HOW a toppled mtm can still be made to look good and sound very good.

Personally, I would get SHOT by the wife if I ever did something like that picture, or get fired by a client if I tried that.

So it is VERY relevant, and the elevation of the drivers across the board is not as important as it seems, except in certain controlled directivity setups. Even then you do have room to spare. I just got in a couple different pa coax's, and they sound wonderful and ear bleeding volumes, but I still cannot get them to sound adequate at regular listening levels ~90-95 db's. Many of my clients will end up leaving the stereo on full time and never touch the tv speakers again, so low volume carries a lot of importance as well.

As far as the acoustically transparent screens, they work great if you can do inwall speakers, but to do that adequately and be able to eliminate the backwave requires a much thicker front wall then normal. Last wall I did required 10" of depth for adequate clearance behind the driver for sufficeint treatment of the backwave and I was able to get better response by varying the elevation of each set of drivers to treat in room modes.

I've done over 20 HT rooms, and trust me, aesthetics are JUST as important as quality. House is a lil different then your car. A lot more people see it. Plus, not too mention things getting knocked over and broken. Nobody enjoys listening to music or watching a movie when your wondering if **** is gonna fall of the shelves or you may step on a wire.

DS, I'm not trying to attack you personally. You may be by yourself and in that case, the aesthetics are purely up to you. But in general, that is why we do the things we do.


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## DS-21

The only picture I've taken of it so far is in this thread. I'll take more early next month. I've commissioned cabinets from Nathan Funk for the LCR's, to replace the ugly Tannoy cabs. (They will be smaller, curved, sealed, but with the same baffle dimensions for hopefully minimal crossover mods required.) I'd just as soon have things finished before I disgust everyone with my abject inability to use a camera.


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## backwoods

me too.

camera's are not my friends..


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## DS-21

Autiophile said:


> I'd like to use the maelstrom for my ULF as well, just need them to come back in stock. Really wish I would have gotten in on the 4th of July sale.


If you want an Ava18 instead, I know of one sitting around... 



Autiophile said:


> In my current home, I would reverse what DS did and put the TV high with the speakers lower, but I have previously had speakers above the TV and it was fine.


I tried that (albeit with my old TV, a 30" LCD) and didn't like it as much. Mounting the speakers high seems to have positive effects on image size. Also, the speakers are off-axis by roughly the same amount when I'm sitting or standing, and I get annoyed by systems that go dull when I stand up to get a drink. Lastly, I was getting floor reflections because of the hardwoods, and due to my flatmate's cat I'm reticent to go pull out any of my vintage carpets.

I agree that it's generally a better-looking solution, though.



Autiophile said:


> I've mentioned it already (and it was shot down as impractical), but a projector with an acoustically transparent screen is a simple and effective means to implement the concept.


That's definitely the obvious and best solution for most rooms, agreed. In my case, this room has a glass door leading out to my balcony, and the projector I tried (InFocus somethingorother, 1080p) just couldn't get bright enough in daylight.



backwoods said:


> nope, you missed more of the point. The speaker sitting on top of the tv has a direct affect on the size of the baffle,


Well, in my case the center is _not_ sitting on top of the TV, which in any case is only about 3" deep. It is behind the TV, on a tall, thin stand from Guitar Center, just like the other two speakers. There is space between the two. I could not hear a difference when treating the top of the TV with foam, felt, or even some scraps of Carlo Barbera Super 160's flannel that were left over from a suit I had CMT'ed. So I left it bare.



backwoods said:


> and a big part of the discussion is why some go with a toppled mtm in spite of it's problems for the aesthetic reasons, in which I mentioned HOW a toppled mtm can still be made to look good and sound very good.


Except that a toppled-MTM can never sound good, and either way you have a speaker in front and center.



backwoods said:


> So it is VERY relevant, and the elevation of the drivers across the board is not as important as it seems, except in certain controlled directivity setups.


Well, in my view every setup that's not contolled directivity is a flawed hack anyway, so basically what you're saying is that fine details such as speaker elevation only matter if one's using fundamentally competent speakers. If one's not, I suppose, who cares. 



backwoods said:


> Even then you do have room to spare. I just got in a couple different pa coax's, and they sound wonderful and ear bleeding volumes, but I still cannot get them to sound adequate at regular listening levels ~90-95 db's.


That's a crossover issue. I've only had that issue once, with a pair of the 8" B&C coax. With the Tannoys, as well as with a Radian 8" coax based design a friend of mine did, no issues like that at all. The 12 DMT II's sound fabulous at a whisper, and fabulous until they get louder than one's ears can take.



backwoods said:


> As far as the acoustically transparent screens, they work great if you can do inwall speakers, but to do that adequately and be able to eliminate the backwave requires a much thicker front wall then normal. Last wall I did required 10" of depth for adequate clearance behind the driver for sufficeint treatment of the backwave and I was able to get better response by varying the elevation of each set of drivers to treat in room modes.


I don't see why a screen needs in-walls. People (not me perhaps, but others) are willing to have TV's that stick out 16" or more, so why not on-wall speakers with a screen that's proud of the wall. Maybe motorized from the ceiling or something.




backwoods said:


> DS, I'm not trying to attack you personally.


No offense whatsoever taken, sir. What's the point of providing information (be it as a picture, words, a cartoon, whatever) if one just expects positive comments? That's no way to move things along.


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## backwoods

the 8" b&c is one of the drivers I have on hand.

I just found out that the local tannoy rep is about 2 miles from my house. Gonna give him a call to see what I can scrounge up.


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## DS-21

backwoods said:


> the 8" b&c is one of the drivers I have on hand.


Are you using the prefab crossover? Just wondering, because it's crap. I'll have to scan in Bernd Timmerman's crossover for it and send it to you, assuming I can find that copy of HobbyHiFi in my cellar.  I used that as my starting point, and ended up with something quite excellent. I wouldn't be surprised if the Tannoy System 8 NFM II's still bested them in direct comparison, though I've never had both on the same continent to make that comparo.


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## backwoods

xover would be great to start with.

I normally test speakers on an active setup to try and familiarize myself with them. For some reason, I have had the hardest time with high efficiency drivers. I need to just stick to it and get more used to them. The sheer output of a 10" midrange is astonishing, and they tend to be fairly flat "outta the box". 

But, I've always struggled with getting tuning to work @ both high & low volumes. I don't know why.


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