Two way LCR for home theater

[NoMjolnir]

Think I'll stick to the Behringer

One more thing, I know one place I'm going to visit the next time I'm in London....

[JBL 4645]

Think I'll stick to the Behringer

One more thing, I know one place I'm going to visit the next time I'm in London....

NoMjolnir

LOL yeah let me guess it called the Empire! You should check it out 56KW and it make any, any, film sing to your expectations! I measured 120dbc at the front of the cinema back on 26th July 2007 Transformers, the pressure and depth of the low end was unquestionably deep. The original JBL THX specification was 13KW! And even that was in my face! So you can imagine what 56KW would be like.

I’m hoping to visit the Empire when Indiana Jones IV opens on opening day May 2008.

It’s truly a JBL inspirational cinema for any JBL fan!


As for the crossover it will only take a small percentage of the planed budget and thou a few like said use here on this site it’s a not a bad investment that works and like all things it has its pros and cons.

The crossover filters are easy to select and use, after you’ve had a few hours (hands on) experience with it.

It does generate a little noise, I’m not going to lie about that, a little hiss on one of the HF band outputs, mostly on the right channel, but it depends on how you set the unit up and use it, with the amplifiers.

Three stereo amplifiers will do a common basic two-way output over its 6 channel outputs.

Or four-way but then you risk the cost escalating because you’ll need at least two DCX2496 because you’ll only have 2 inputs to use then and only (three outputs LMH, LMH)

Its easier to stick with (left LH centre LH right LH) and then use a second one for the surrounds if you wish so, to do (sidewall surrounds and centre back surround) in the same fashion as the fronts.

A third can be used for sub bass arrays of subs placed in the baffle wall and then with the DCX2496 you can tailor the sound to the, likens of the rooms inner surroundings.

[NoMjolnir]

THX screens usual use plasterboard but that can be a messy affair. There are other types of (affordable materials) to use for a (baffle wall) that don’t cost.

Baffle wall 16cm, perhaps 30mm chipboard(?) on each side and 100mm insulation? Chipboard would be easy for flushmounting of drivers. The front of the baffle wall should perhaps be 30mm MDF for mounting of the drivers ?

Don’t forget the absorbent material to cover over the (barrier wall surface), because that part where Tom Holman, mentioned the (reflectivity bouncing around behind the screen) was fascinating

For the ceiling I'll use black/grey ecophone acoustic panels. I was thinking I could use the same on the baffle wall. Side and back walls will be greyish and floor will cherry stalls (?) but with carpet between seating area and front wall.

The length of the HF horn is what I looked at because of the shrinkage of the rooms depth will decrease once you place this and the (compression driver on the back) I think another 3” of room depth space will be lost, 13” for the HF and compression driver?

Hopefully with 40-45 cm I'll be able to access this area and there will be more space from the back wall to the sub drivers. I'm considering using 4 soundsplinter 18" in an LLT configuration, these drivers will also be flushmounted in the baffle wall. The baffle wall should probably be anchored to the back wall considering the moving mass of the 18"'ers.

I presume that the LF drivers of the LCR's will have their own enclosures behind the baffle wall.



I've made a new sketchup model just for the ht room. The inner walls, ceiling and floor are mechanically decoupled creating a room within the room. In the back I'll have bass trapping in the corners. The entire ceiling is 280cm with 30cm of insulation before ecophone acoustic panels making it a bass trap.

[JBL 4645]

NoMjolnir

Afternoon there sorry for the long post.

Oh yes I like that I what you’ve done with the computer model.

So I take it the front loudspeakers LCR will be ported from what position? Front ported or rear ported because nearly all the cinema types are ported from the (front) subs as well.

So the 18” sub bass drivers, won’t have there own enclosure or will they? If that’s so will you install them into the fittings, that is the hole in the wall and then use some wood edging to over up the gaps around it, not that it’s a paramount issue.

The wall should have an (absorbent material) that comes of a role and from what I have seen in pictures, it appears to be fitted all around the edges or you can staple it to the wood, that’s just a fast and cheap option.

If I get an opportunity like you have at the moment I would like to do the same thing, but there’s no point if you don’t have a video projector.

I must say that the few THX screens that I have been to in the UK and sound engineers in the UK take great pride in getting the best and more out of it, that’s just a personal opinion of mine.

There was one other THX screen that used to be THX certified during the late (1988 to 1999 2000)? High Welcome UCI or CIC as it used to be called.

This cinema could do dual 35/70mm film presentations and had JBL 4675-A five screen and two JBL 4645 subs not sure how many JBL surrounds they had or what model they where.

But when I saw Arachnophobia (1990) at the cinema I was BLOWN AWAY the bass sub bass was very tight it was in my (chest stomach face) all over me and still to this day I can remember what it felt like, call it if what (THX syndrome)

There’s only so much my JBL control 5 and 1 can do at the front, given where there positioned, there’s only so much the sub bass extension can do within technical tolerances and there is only so much the LFE.1 can do when playing Arachnophobia on region DVD.

There seems be a few low frequencies that need addressing or I need larger matching JBL for LCR. Most of the deep bass is generated from the centre channel, but like I said there’s only so much each loudspeaker is capable of, I’m not trying to put my home cinema down, it has limits and as long as I know where it can go and where it can’t go I tend to keep it within its (technical tolerance level).