[zacjones]

So I'm building a CIH theater with a 120" wide 2.40:1 AT screen. The L/R WWCWW speakers will be wall mounted at the appropriate height, but I am unable to mount the center channel at the same height due to the presence of a window 8' wide and 4' tall directly behind the screen. My wife absolutely will not let me mount the center channel suspended in front of the window.


So for now I need to figure out the best way to raise the vertically oriented center channel speaker up by 30". The speaker will be a sealed version of the JTR Quintuple. 43" tall, 9.625" wide, 7.5" deep, likely weighing in at about 80#. The speaker will be as tight to the front wall as I can get it. It will look like a floorstanding speaker, on the floor just in front of and below the window, before the button is pushed to raise the speaker to the same level as the L/R speakers.


A few pictures are worth a thousand words:


Here's are some photos and models of the area with old screen and old speakers

OK here's a model of what I'm trying to do: Here's the recess area with the theater "closed" and the center channel at rest as a floorstander.

And here's the recess area with the theater open and the center channel raised 30" to the level of the mains.

So far I'm looking at two options:


Option #A

http://www.firgelliauto.com/product_...roducts_id=213


Use a linear track actuator with 30" travel by firgelli auto. It fits completely behind the speaker and would seem to work if I can somehow make it support and balance the speaker. I'm thinking a large custom fabricated L bracket that covers most of the back and the entire bottom of the speaker. This would be the most elegant solution I have come up with if it can be done. I'm still trying to come up with additional ways to support the speaker such as cabinet drawer or shelf slides, but I haven't been able to come up with any that have a 30" extension yet. The actuator has two mounting locations, one on each end -- I would be mounting the actuator vertically on the wall and to the floor. I would be mounting the speaker below its center of gravity, with the center of the mount at about 6" from the bottom of the speaker.



Then there is option B:

http://www.teamhawgracing.com/produc...1.1.0.0.0.0.0?


The less elegant BMX motorcycle lift! Probably a little sturdier though as I can screw the speaker right down into the top plate of the lift and feel fairly confident about the speaker's balance. Who knows though if the thing will rattle with a massive IB subwoofer system just inches away! I'd actually use a linear actuator instead of the hydraulic foot pump to make this thing raise and lower.




So needless to say, I'd like to try and make option A work. Anyone? Doomed to fail or do I have a shot with it?


I'm most concerned about the speaker wanting to tilt forward.

 

[matthewa]

Why not just have a fixed stand rather than a lift?

 

[CAVX]



Quote:
Originally Posted by zacjones /forum/post/20864841


And here's the recess area with the theater open and the center channel raised 30" to the level of the mains.

A few questions and possible suggestions:


Q1. How are you sealing the window up? AT screens will let light pass from both sides and nothing is more distracting that light coming from behind an AT screen.


Q2. You drew the centre sitting just under the window. Can you redraw that with the screen in place? Whilst not at the same height as the L and R, there is (on the H plain) driver over lap and you might get away with that. Of course ideally you want the three LCRs to be at the same height.


Q3. You have your L ad R out side the screen area. Is there any reason for that? I would move them in if you can. Your screen is AT, so why not have all three behind the screen?


Q4. I know this might sound like a compromise, but given your screen raises up when not in use, why not build a stand that you can place the centre speaker on when you are using the system? You could simply unplug it (assuming Banana plugs) and place it to one side when your wife wants to use the window.

 

[230-SEAN]

Mark's first question was my main concern. While I was reading the post I couldn't figure out why you couldn't put a speaker in front of what used to be a window, then realised you are still planning on having a retractable screen but it will be AT. I would suggest not doing this if the window is to remain a window, it is just a bad idea and you will most likely end up rarely using your theater due to the frustration it will cause you from image the you will have. If you think some ambient light in a room messes with your PQ, wait until that light is shinning through the screen and you have no control over it. Maybe you could install some nice blackout curtains, but it doesn't appear that you would have much room as the screen is installed where the curtains would need to be.


-Sean

 

[zacjones]

Thanks Mark and Sean for helping me out with this.

Q1. How are you sealing the window up? AT screens will let light pass from both sides and nothing is more distracting that light coming from behind an AT screen.


I will make a folding AT panel out of 2" OC703 to fit inside the window sill, with a 4" flap around the perimeter and neodynium magnets sewn into the fabric to extend over the window casing and hold the panel in place. This will be a very well light controlled room when I'm done with it.


Q2. You drew the centre sitting just under the window. Can you redraw that with the screen in place? Whilst not at the same height as the L and R, there is (on the H plain) driver over lap and you might get away with that. Of course ideally you want the three LCRs to be at the same height.


Unfortunately I'm unable to do another drawing right now as I don't have my files with me. But the problem with that scenario is that the coaxial driver would be firing from directly behind the non-AT screen border. No can-do. Alternatively, I could mount the coaxial driver in the uppermost driver location of the cabinet, but I've heard from people who have done this with the JTR triple 8's that the response just was not as good with the coaxial in a location other than the center of the baffle. Even if I were to do that I'm still not happy about the midbass drivers firing into the non-At screen border -- there's still a lot of dialogue in 80-200hz.

Q3. You have your L ad R out side the screen area. Is there any reason for that? I would move them in if you can. Your screen is AT, so why not have all three behind the screen?


Well the main reason is that, again, the window is in my way. If I were to mount the speakers just outside the window casing, they would basically come right up to, and 1/8" past, the lateral borders of the AT screen and into the non-AT screen border. Now the speakers will be about 2" behind the screen and have a fairly wide off-axis response, so mostly I am concerned about the effects of the speakers firing into the screen border. I did consider mounting these main speakers on cabinet drawer slides and scooting them in either manually or with an actuator, but moving them out and mounting them on the side walls of the recess would accomplish a few things -- it would allow me to bring them forward and get the planes of the baffles out of the recess, and it would bring them closer to being the same distance to the listener as the center channel. This configuration would have the listening angle of the tweeters at about 28 degrees from center, while placing them behind the screen just outside the window casing would be right at 22 degrees from center. I could get the speakers 4" farther in, where I would be comfortable with them not radiating into the AT panel, by mounting them over the window casing without encroaching into the window space, but my wife still prefers the outside mount option. While they are only guidelines, THX calls for 22.5 degrees while Dolby HT calls for between 22-30 degrees. So either of the placements would probably be OK. I think I'll cross that bridge when I come to it and I have the speakers in the room, factoring in performance vs aesthetics, and hopefully I'll catch my wife on a good day.


Q4. I know this might sound like a compromise, but given your screen raises up when not in use, why not build a stand that you can place the centre speaker on when you are using the system? You could simply unplug it (assuming Banana plugs) and place it to one side when your wife wants to use the window.[/quote]


This is definitely an option if the speaker lift proves too difficult or ends up looking like it's going cost more than just the actuator and some shelf or drawer glides.



Mark's first question was my main concern. While I was reading the post I couldn't figure out why you couldn't put a speaker in front of what used to be a window, then realised you are still planning on having a retractable screen but it will be AT. I would suggest not doing this if the window is to remain a window, it is just a bad idea and you will most likely end up rarely using your theater due to the frustration it will cause you from image the you will have. If you think some ambient light in a room messes with your PQ, wait until that light is shinning through the screen and you have no control over it. Maybe you could install some nice blackout curtains, but it doesn't appear that you would have much room as the screen is installed where the curtains would need to be.


I couldn't agree more. I'm thinking the acoustic panel will kill two birds with one stone.


Thanks again for your responses. What do you think about the lift?

 

[zacjones]

And then there is option C -- a horizontal Center Channel under the window, on a 30" stand. For critical listening the speaker could be set vertically on the stand. This is actually a really good option that I just came up with. Definitely the best option side from having the lift.


I'm trying to get someone on the phone over at Firgelli auto. They've only recently added phone service so I'll keep trying until I get someone.


and you can't forget about option D -- A 30" center channel TV stand securely mounted to the floor. The Center channel sits on the stand in the proper position along with the mains, but is attached to the stand with a hinge on the front of the stand. Attach a leather strap to the sides of the speaker near the top. You want to lower the speaker, just grab the strap and pull forward, arcing the speaker forward until it hits the fully lowered position (the stand would have built-in padded stops). Unfortunately the stand would have to be 45" tall to bring the speaker to a fully descended vertical resting position, so on a 30" stand the speaker would rest at about a 42 degree angle and come out about 40" into the room. That might look kinda funny.

 

[zacjones]

Well it didn't take me long to get ahold of a very helpful individual at Firgelli auto. We went through the scenario and could really find no reason why it wouldn't work, so even though I stumbled upon a pretty good solution with just a 30" stand where I could change it to vertical as needed, I think I'll go ahead and go with the lift. At $199 it will probably will not cost much more than a nice center channel speaker stand!


If for whatever reason the speaker lift doesn't work out to my satisfaction I will just mount the actuator in the attic and use it with a pulley system to raise and lower the screen housing. I don't really have as much drop built into the screen as the image shows, so actually for the screen to be at that height the screen housing would have to be suspended in front of the window. Again with the window in the way. That window is my nemesis!


Thanks again y'all!

 

[jpeter1093]

This is why I love this hobby. Creative solutions to problems. We're all engineers.