Building Custom Home Theater

[Rich]

This thread does not involve Martin Logan speakers, but I thought you guys might be interested. I am building my dream home, as it were, and part of that is building a custom home theater room. This room will be about 18.5 feet wide by 22.5 feet long and about 10 feet of ceiling height. It will have two rows of five seats. It will be soundproofed and professionally acoustically-treated. The room was designed by Nyal Mellor of Acoustic Frontiers. The sound system will be a 9.4.6 system. Equipment will include 3 JBL SCL-2’s for the LCR channels, 6 SCL-7’s for the wides and side and rear surrounds, and 6 SCL-5’s for the Atmos channels. I will use AudioControl amps and a JBL SDP-75 processor (basically a re-badged Trinnov Altitude 32, except it includes anechoic files for the SCL speakers). Four Power Sound Audio (PSA) TV-21 IPAL’s will handle sub duties. These consist of four 21” pro-style woofers, with 4000 watts going to each woofer from rack-mount SpeakerPower amps. I plan to have a JVC NZ-9 laser projector and a Stewart Studiotek 100 138” diagonal 16:9 screen. I’m really trying for an end-game home theater here. I’ll keep you all advised of my progress.

 

[Rich]

Here’s a few photos of where I’m at currently. This is the house at the moment…

Here’s the view out my front door…

And here’s the theater currently…

Lots more to come as construction progresses.

 

[ttocs]

Wow! Very nice!
Which room is mine?

 

[Rich]

Wow! Very nice!
Which room is mine?

Well, the guest room of course!

 

[Robert D]

Here’s a few photos of where I’m at currently. This is the house at the moment…
View attachment 23768

View attachment 23771

Here’s the view out my front door…

View attachment 23769


And here’s the theater currently…

View attachment 23770


Lots more to come as construction progresses.

How will you deal with the big window to the right? So much light.

 

[Rich]

How will you deal with the big window to the right? So much light.

There are actually two windows in the rear and a big glass Palladian-style door (on the right) in the room. These will be plugged and sealed. When you are in the room, you won’t know that they exist. The walls will all be fabric-covered to hide the in-wall speakers and all the acoustic treatments. The fabric walls will cover the door and windows as well, so from the interior you won’t see them or have access to them. They were necessary for the exterior architectural detail, but serve no purpose in a dedicated home theater.

 

[JonFo]

They were necessary for the exterior architectural detail, but serve no purpose in a dedicated home theater.

Ah, whew, I was worried for a bit

Great progress so far, and the design of the HT sounds great. Looking forward to seeing it in person someday.

The gear selection is great; since the SDP-75 is a Trinnov in JBL clothing, you should have access to the Atmos object 3D visualizer, which is one of many cool features of that unit.

 

[Rich]

To add some detail on the room construction…

Three of the four walls are ICF, which is a 6” thick concrete wall sandwiched between two 2.5” layers of styrofoam insulation. These walls are all exterior walls for the most part, and will have an eifs stucco finish on the exterior.

The wood frame wall (on the left in the pic) is a double wall for soundproofing purposes. It consists of a 2x4 wall on the theater side and a 2x6 wall on the other side. Each wall sits on it’s own floor truss and they do not touch nor does the inner wall touch the ceiling joists. There is a half inch gap between them, which I will caulk with acoustic caulk at the subfloor. These walls will be filled with rockwool insulation and have two layers of 5/8” type-X drywall (with green glue between the layers) on both sides of the double wall system. The subfloor consists of two layers of 3/4” OSB sandwiched with green glue, and will have insulation below it. The floor trusses are all attached to the concrete walls. The room below is a garage. The entry door to the theater will be two communicating soundproof doors, one in each of the wood frame walls. The equipment rack is located in a separate closet just outside the theater.

The ceiling will have a clip and channel system (along with the same two-layer with green glue drywall system) to reduce sound transmission into the attic above. There will be a thick layer of rockwool insulation above the ceiling as well. So as you can see, I’m going to great lengths to make this room as soundproof as possible. Given the speakers and subs that I have, good soundproofing will be key to my being able to fully enjoy the room without disturbing the rest of the house. It should also provide a very low noise floor in the room itself.

 

[Rich]

Ah, whew, I was worried for a bit

Great progress so far, and the design of the HT sounds great. Looking forward to seeing it in person someday.

The gear selection is great; since the SDP-75 is a Trinnov in JBL clothing, you should have access to the Atmos object 3D visualizer, which is one of many cool features of that unit.

Hi Jonathan. Yes, that’s why I chose this processor. You get the majority of the benefits of the Trinnov, along with the anechoic data files for the JBL speakers. Best of both worlds. The unit I purchased has 24 channels, of which I’ll use 22. This way I can bi-amp the SCL-2 LCR speakers, as well as have each sub on a separate channel (to hopefully take advantage of Trinnov’s forthcoming bass management algorithms). We’ll see about that. I’m kind of taking a leap of faith that Trinnov is headed in the direction that I think they are regarding bass management in the Trinnov optimizer.

 

[JonFo]

The unit I purchased has 24 channels, of which I’ll use 22. This way I can bi-amp the SCL-2 LCR speakers,

Very nice. Does the SCL-2 have an order option to skip the passive XO, or a way to completely bypass the passives?

This ability to do the XO in the preamp is one of the big draws the Trinnov has for me, as it'd simplify my rig a bit.

have each sub on a separate channel (to hopefully take advantage of Trinnov’s forthcoming bass management algorithms). We’ll see about that. I’m kind of taking a leap of faith that Trinnov is headed in the direction that I think they are regarding bass management in the Trinnov optimizer.

I fully expect them to deliver on that. And I'm banking on that as well.

 

[Rich]

Very nice. Does the SCL-2 have an order option to skip the passive XO, or a way to completely bypass the passives?

This ability to do the XO in the preamp is one of the big draws the Trinnov has for me, as it'd simplify my rig a bit.

Honestly, I haven’t done as much research into this as I should have. I know that bi-amping them skips the passive crossover, but I’m unsure whether I can use the Trinnov for crossover duties (I’m expecting I can do this) or whether I need to buy external crossovers directly from JBL. I need to confirm this one way or the other. Thanks for bringing it up. I’ve been so busy with other details that I forgot to get confirmation on this.

 

[Robert D]

There are actually two windows in the rear and a big glass Palladian-style door (on the right) in the room. These will be plugged and sealed. When you are in the room, you won’t know that they exist. The walls will all be fabric-covered to hide the in-wall speakers and all the acoustic treatments. The fabric walls will cover the door and windows as well, so from the interior you won’t see them or have access to them. They were necessary for the exterior architectural detail, but serve no purpose in a dedicated home theater.

Wow, ok. That makes sense. So you had the windows and doors put in for exterior aesthetics. It should be much better for resale value someday too, as the next owner may decide to use them. It gives options.

 

[Robert D]

Ah, whew, I was worried for a bit

Great progress so far, and the design of the HT sounds great. Looking forward to seeing it in person someday.

The gear selection is great; since the SDP-75 is a Trinnov in JBL clothing, you should have access to the Atmos object 3D visualizer, which is one of many cool features of that unit.

What is the Atmos 3d visualizer? Similar to the Auro 3d software?

 

[Robert D]

To add some detail on the room construction…

Three of the four walls are ICF, which is a 6” thick concrete wall sandwiched between two 2.5” layers of styrofoam insulation. These walls are all exterior walls for the most part, and will have an eifs stucco finish on the exterior.

The wood frame wall (on the left in the pic) is a double wall for soundproofing purposes. It consists of a 2x4 wall on the theater side and a 2x6 wall on the other side. Each wall sits on it’s own floor truss and they do not touch nor does the inner wall touch the ceiling joists. There is a half inch gap between them, which I will caulk with acoustic caulk at the subfloor. These walls will be filled with rockwool insulation and have two layers of 5/8” type-X drywall (with green glue between the layers) on both sides of the double wall system. The subfloor consists of two layers of 3/4” OSB sandwiched with green glue, and will have insulation below it. The floor trusses are all attached to the concrete walls. The room below is a garage. The entry door to the theater will be two communicating soundproof doors, one in each of the wood frame walls. The equipment rack is located in a separate closet just outside the theater.

The ceiling will have a clip and channel system (along with the same two-layer with green glue drywall system) to reduce sound transmission into the attic above. There will be a thick layer of rockwool insulation above the ceiling as well. So as you can see, I’m going to great lengths to make this room as soundproof as possible. Given the speakers and subs that I have, good soundproofing will be key to my being able to fully enjoy the room without disturbing the rest of the house. It should also provide a very low noise floor in the room itself.

Decoupling the walls, ceiling, and floor fully it sounds like. That alone excites me! It's like when I was a kid and got a look at a playboy centerfold! Audiophile ****.

 

[JonFo]

What is the Atmos 3d visualizer?

It is a rendering of the position and levels of the objects in a graphical view; see this:

 

[JonFo]

I’m unsure whether I can use the Trinnov for crossover duties (I’m expecting I can do this) or whether I need to buy external crossovers directly from JBL. I need to confirm this one way or the other.

For sure, the Trinnov can do the XO duties; It's why I'm seriously looking at a 24 Channel Alt32 for myself, as I want to get rid of the DBX boxes and have less cabling.

I looked at the JBL page for the SLC-2, and it is a 2.5 way XO design, so at most, you could XO highs to low, but the low section would still need the passive. The SCL-2 does natively support bi-amping,

 

[Brandon Hartwick]

4 21" subs should handle the bass nicely for sure. Years ago when I was still living at home I build a pretty serious HT setup in the basement almost entirely from used gear and I had a RCF 21" woofer in the adjacent room. It would play 30HZ and down through a furnace vent in the door, in a 20+ cubic foot ported box it would move your insides around.

Looks like lots of fun, look forward to seeing more.

 

[Rich]

4 21" subs should handle the bass nicely for sure.

Yeah, I’m hoping to get a fairly flat response from 10 Hz on up. Should be amazing. And with the headroom I’ll have on the TV21 iPals with 4000 wpc, sub distortion should be non-existent even at high volume levels. Progress has been slow, but it’s picking up. 12 gauge speaker wire has been run to all speakers. Sub wire is next. I’m running two runs of 10 gauge wire to each sub from the rack-mounted SpeakerPower amps! That will be the equivalent of about a 7 gauge wire.

I finally got my hvac muffler boxes installed. These are large enough to reduce airflow to 200 feet per minute. I needed a maximum of 250 fpm to keep things quiet, so this should totally eliminate the sound of whooshing air from the hvac. They will be connected to the unit with a long run of 10” insulated flex tube with a few twists and turns. And they are lined with linacoustic RC, so that should help muffle sound traveling to the room from the unit, as well as sound traveling from the room back through the hvac system. I’m getting ready to install a clip and channel system for the ceiling and install some recessed light fixtures in the soffits. Then I’ll be ready for insulation and drywall. So things are moving along. I’ll post some more pics when I’ve got something interesting to share.

 

[Brandon Hartwick]

You should consider some nearfield subwoofers as well, they seem to be worth looking into. I keep seeing people with great results and I want to try it.

 

[JonFo]

You should consider some nearfield subwoofers as well, they seem to be worth looking into. I keep seeing people with great results and I want to try it.

Seconded, I find the experience to be much better thanks to the nearfields. The Trinnov (er JBL) can do the XO and time alignment for those.

But your JBL speakers produce decent mid-bass, so I'd wait until the system is operational to judge.