# LCR positioning w/AT screen - ear height vs screen height?



## odin (Jul 26, 2014)

Greetings from Norway, this is my first post on this very knowledgeable forum! 

I am building a small dedicated home theater room using the original M&K S150/SS150/MX350 THX speakers, and have some questions about the vertical/horizontal placement of the front LCR speaker array.

*Some info about my room:*
My room is quite small, cirka 11' wide by 16' long. Ceiling height is 7' 10".

I will have two rows of seating with a 12" riser at the back of the room.

I will be mounting the speakers in a baffle wall behind a AT screen. The screen will be about 105” wide (2,35:1 or 16:9 TBD).

*The challenge...*
On one hand I want the best possible dispersion and sound clarity at the listening position. On the other hand, I also want the sound to connect with the action on screen. For example, it is recommended by THX "that the speakers be placed 5/8 the height of the picture screen(…)to ensure that sound elements relate best to the image.”

*So...should i mount the LCR speakers: 
*
1)	at ear height as recommended by M&K
2)	at around 5/8 of the screen height, with the speakers angled down toward listening area, as recommended by THX
3)	somewhere in between? 

Also some questions with regard to the horizontal orientation. Since I am somewhat limited by the narrow room, should it be a priority to achieve a 45 degree listening window, or to keep the L & R speakers well away from side walls and screen frame, to limit early reflections? 

I did try searching the forums but would appreciate some fresh opinions & experiences on the matter! I guess the downside of building a baffle wall, is that the speakers are harder to move after the fact! 

Thanks!

Best regards 

Odin


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## gazoink (Apr 17, 2013)

odin said:


> Greetings from Norway, this is my first post on this very knowledgeable forum!
> 
> I am building a small dedicated home theater room using the original M&K S150/SS150/MX350 THX speakers, and have some questions about the vertical/horizontal placement of the front LCR speaker array.
> 
> ...


THX also says the screen height should be such that to view the center of the screen there is no more than a 15 degree upward angle. 

If your screen height meets that requirement of 15 degrees up or less, put the tweeter at 5/8 the height, angle downward by the same angle as the viewing angle to the center. If your speakers have multiple tweeters, use the top one as the measurement reference for height.


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## odin (Jul 26, 2014)

Thanks! I am looking to buy a 105" W / 45" H, 2,35:1 screen which would meet that requirement. My viewing distance is about 10'. I am using the M&K S150 which has three tweeters stacked vertically.


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## Andre (Feb 15, 2010)

I would set using M&Ks recommendation to start then listen to them in the room at the intended seating position and move them to achieve their best sound in the room.


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## gazoink (Apr 17, 2013)

The S150s are THX Ultra2 speakers. Their vertical dispersion angle is controlled to +/- 15 degrees, their horizontal is much wider, +/- 30 degrees. The concept is to keep first reflections off the ceiling and floor, but to cover a wide seating area. 

You'll want to aim them at a point in the middle of the seating area such that all ears are covered. The amount of tilt-down is still driven by the screen center elevation. You may also want to toe them in if your screen is wide in relation to the seating area. 

Do you have the original S150s or the S150 Mk IIs?


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## odin (Jul 26, 2014)

Hi Gazoink, they are the original S150s from Miller & Kreisel, from around 2005 IIRC. I have the towed in L&R versions and the angled center (S150AC). I can get some Auralex Mo-pads or similar to tilt the L&R speakers down.


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## gazoink (Apr 17, 2013)

odin said:


> Hi Gazoink, they are the original S150s from Miller & Kreisel, from around 2005 IIRC. I have the towed in L&R versions and the angled center (S150AC). I can get some Auralex Mo-pads or similar to tilt the L&R speakers down.


Those are great speakers, as I'm sure you know. You should be aware that there are no more drivers in the world. If people blow a tweeter it's always the center one since that has most of the power routed to it. It's no longer replaceable, and not repairable. The woofers are indestructible unless you have a catastrophic amp failure, which will also toast the crossover. Good news, the crossover can be rebuilt, I've done several. 

The current MKII version has been redesigned, so if you wanted to replace a single tweeter with a current unit, you have to replace all three (the upper, middle and lower aren't identical), you can calibrate the resulting difference out with EQ. THe AC is different from the L/R, parts are not interchangeable. 

Take care of them, they'll last another decade at least. Just thought you should know the current story from someone who knows them inside and out. People keep coming to me for repairs, but there's not too much I can do anymore.

Everyone else...sorry to go off topic.


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## odin (Jul 26, 2014)

That's great knowledge, thanks! Yes they are great speakers, I think the dialogue reproduction is especially good. I will take good care of them for sure. I'm not about playing at reference levels all the time. Will have to find a good amp to feed them some clean power 

I have seen some mention of the "pro tweeters" in the current version. Are those interchangeable using the old crossover, using some EQ? 

I want to try them in a baffle wall, do you think the S-150s could benefit from this at all? I've had positive experience with Procella speakers that way, but they are very different speakers of course.


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## gazoink (Apr 17, 2013)

odin said:


> That's great knowledge, thanks! Yes they are great speakers, I think the dialogue reproduction is especially good. I will take good care of them for sure. I'm not about playing at reference levels all the time. Will have to find a good amp to feed them some clean power
> 
> I have seen some mention of the "pro tweeters" in the current version. Are those interchangeable using the old crossover, using some EQ?


Yes, you can sub the current version tweeter, but you have to change all three, and the response won't match the old speaker (or a new one either), but you can EQ that out.


odin said:


> I want to try them in a baffle wall, do you think the S-150s could benefit from this at all? I've had positive experience with Procella speakers that way, but they are very different speakers of course.


A baffle wall will always kick up the bass with any speaker. The S150 doesn't need it, and was designed to work to THX spec without it. If you get a few dB in the bass, then Eq the system, you'll be mostly taking that back out anyway.


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## gazoink (Apr 17, 2013)

Are these behind an AT screen?

Are you going to fuzz the wall behind them?


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## odin (Jul 26, 2014)

Yes, my plan is to mount both the LCR and subwoofer in the wall behind the AT screen. I'm essentially building a new wall which will span from wall to wall, floor to ceiling and be covered in black absorbant.


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