Here we go again - A new dedicated theatre

[scottrichardson]

Hey all, so it seems the HT gods are shining down upon me today as our renovation discussions about adding an extra small living space and bedroom have now turned into:

 

1. converting my existing HT into a small study and bedroom for our baby boy and,

2. building a new, fully dedicated theatre and lobby/entry where our current back deck is

 

I am having a tradesman pop around today for initial discussions, but wanted to get this out to all of you wonderful HT gurus and I want to be clear about something:

 

I want to get this right! I am seeking advice on how to achieve great acoustics, and an ideal size/dimensions for the best results. I will be keeping all my existing equipment, and will likely purchase more subwoofers.

 

FYI here's my existing room:

 

- 4.4m wide x 5.4m long x 9.5ft ceiling. 

- two rows of seats with rear row on a riser

- 165" scope screen Majestic 4K from OzTheatre Screens

- JVC N7 Projector

- Aussiemorphoc Mk IV lens + slidamorphic motorised lens slide

- 7 x Power Sound Audio MTM 210 speakers

- 4 x Power Sound Audio MT110 SR speakers

- 1 x Power Sound Audio s3600i dual opposed 18" subwoofer w/1800 watts amp

- Marantz 8805 processor

- 2 x 7 channel Elektra theatre HD2 power amplifiers (7 x 190w RMS each)

- Apple TV 4K

- 2 x 3 seater couches each with 2 x motorised recliners

 

The current room is good, but a shade small if I'm honest, given the two rows of seats, and the depth required for the MTM210 speakers. My back row of seats is awfully close to the back wall, and the side surrounds are quite close to the listener. Accoustically, the bass response around the seats is very uneven, most likely due to the single sub. The bass is extreme at the rear corners of the room, and the back row of seats experiences a very different sound than the front row. The 'directors' chair IMHO should be the front middle seat, but the bass nulls there are prominent.

 

All my electronics are sitting between the centre and right speaker. My sub is positioned between my left and centre speakers. All bed channels are on the floor currently.

 

Goals for new room:

 

1. Better bass response (more subs?)

2. More space

3. AT screen with speakers behind screen in false wall

4. Actually ceiling mounting my atoms channels vs high on the wall where they are now

5. Adding front wide speakers

6. Adding provisions for extra 2 atoms channels

7. Better acoustic panels rather than foam tiles - happy. to go home made

8. Make the room feel 'finished'

9. Vaulted ceiling with LED strip

10. 'hush' box for the projector to make it less noisy

11. Equipment in a rack in the 'lobby'. - IR repeater etc

 

So am now open to suggestions and advice. Space is not unlimited, but I can probably afford to go a little bigger than my current room. Maybe an extra meter in each dimension.

 

Attached is an image of my current floor plan and a very rough mockup of where the new theatre would go. The old theatre will turn into a study and bedroom.

[Kaynin]

Yeah squeezing in two rows of seating might be a compromise.  If you really want that then extra length in the room would be important.

 

If you’re going to this expense then I’d get the room acoustically tested.  Don’t assume a second sub will fix issues.  Placement is vitally important, and correct testing will properly inform you.
 

Glad you’re looking at room treatment.  Home made is good, but how do you know it’s correctly targeting issues within the room?  The commercial gear usually comes with specs that informs you what area is targeted, home made may not.  It has such a big impact, important to get right.

 

It’s going to be a nice room, very exciting.

[Quark]

Sounds like the makings of an outstanding room.

 

A couple of thoughts:

1. An AT screen will have a lower gain than your Majestic screen - not sure you will have enough lumens for HDR on a 165" scope screen.
2. For your hush box, make sure you use optical quality glass if you use any glass in the box. Can be sourced from Edmund Optics.

[scottrichardson]

1 hour ago, Quark said:

A couple of thoughts:

1. An AT screen will have a lower gain than your Majestic screen - not sure you will have enough lumens for HDR on a 165" scope screen.
2. For your hush box, make sure you use optical quality glass if you use any glass in the box. Can be sourced from Edmund Optics.

 

Yes the 165" screen is certainly already at the brightness limits. I don't really want to go much smaller than that. How much gain would I lose by going with some form of microweave style AT screen? What's my real only option above and beyond the JVC, a $69,000 BARCO? Pretty sure I'll be spending less than that for the entire room build haha! Happy to sacrifice a few inches, but not too many.

[davewantsmoore]

3 hours ago, scottrichardson said:

1. Better bass response (more subs?)

2. More space

3. AT screen with speakers behind screen in false wall

4. Actually ceiling mounting my atoms channels vs high on the wall where they are now

5. Adding front wide speakers

6. Adding provisions for extra 2 atoms channels

7. Better acoustic panels rather than foam tiles - happy. to go home made

8. Make the room feel 'finished'

9. Vaulted ceiling with LED strip

10. 'hush' box for the projector to make it less noisy

11. Equipment in a rack in the 'lobby'. - IR repeater etc

 

1.   Yes, more subs..... consider smaller ones, which don't play all the way down to "jurassic park", to smooth the 50 to 150 region, which is such a problem in small rooms.

2.  Go as large as you can.

5 and 6.   I think your room is too small.

11.   Don't skip this.  It saves heaps of space, and takes heat and 'blinkenlights' out of the room.

 

[Guest niterida]

16 minutes ago, davewantsmoore said:

5 and 6.   I think your room is too small.

Not at all - for 2 rows of seating the 3rd row of height speakers is recommended - can then put the rear heights further back behind the rear row instead of in front.

Plenty of room for wides - everyone on AVSForum.com say that adding wides has been a huge improvement for them and most advocate going to wides before going to 6 heights. I have a 6.25x4.3m room and plan on adding wides when funds for an upgraded processor and 2 speakers are forthcoming.

 

I think you have pretty much nailed everything in your drawing except for moving your seating a bit further back to keep your ears out of the midpoint - they should be at 1/3 room length from the back wall and 2/5 at most. And maybe move your height speakers out a bit wider so they are outside the outer seats.

[scottrichardson]

6 hours ago, davewantsmoore said:

 

1.   Yes, more subs..... consider smaller ones, which don't play all the way down to "jurassic park", to smooth the 50 to 150 region, which is such a problem in small rooms.

2.  Go as large as you can.

5 and 6.   I think your room is too small.

11.   Don't skip this.  It saves heaps of space, and takes heat and 'blinkenlights' out of the room.

 

 

Thank you! Yes, considering selling my dual 18" and getting 4 x sealed 18" subs. Should play just fine down low with the MiniDSP in action?

 

Estimating the internal room dimensions will be about 5.5m wide x 6.5m deep and 10ft ceiling at highest point.

 

100% equipment will be outside in lobby!

[scottrichardson]

6 hours ago, niterida said:

Not at all - for 2 rows of seating the 3rd row of height speakers is recommended - can then put the rear heights further back behind the rear row instead of in front.

Plenty of room for wides - everyone on AVSForum.com say that adding wides has been a huge improvement for them and most advocate going to wides before going to 6 heights. I have a 6.25x4.3m room and plan on adding wides when funds for an upgraded processor and 2 speakers are forthcoming.

 

I think you have pretty much nailed everything in your drawing except for moving your seating a bit further back to keep your ears out of the midpoint - they should be at 1/3 room length from the back wall and 2/5 at most. And maybe move your height speakers out a bit wider so they are outside the outer seats.

 

Thank you. Yeah I think the Atmos channels will be wider than that. I will post a proper room mockup once we have more talks with the trades guys. I almost have room for wides already in my current room so I should be fine with an extra meter in each dimension!

[Quark]

7 hours ago, scottrichardson said:

 

Yes the 165" screen is certainly already at the brightness limits. I don't really want to go much smaller than that. How much gain would I lose by going with some form of microweave style AT screen? What's my real only option above and beyond the JVC, a $69,000 BARCO? Pretty sure I'll be spending less than that for the entire room build haha! Happy to sacrifice a few inches, but not too many.

 

With 1.1 gain, you would lose about 13%, with 1.0 about 21%.

 

JVC are meant to be bringing out laser models soon - these might be a decent step up in lumens and should have the benefit of little if any loss of lumens as they age.

 

[hopefullguy]

will you be buying front wides? ie: psa mtm210's.. cant get them here anymore and they are very expensive these days from the U.S.

[scottrichardson]

11 hours ago, Quark said:

 

With 1.1 gain, you would lose about 13%, with 1.0 about 21%.

 

JVC are meant to be bringing out laser models soon - these might be a decent step up in lumens and should have the benefit of little if any loss of lumens as they age.

 

That sounds great! Worst case scenario is I just lump the lumen drop until new laser models come out. 
 

what’s the resale value like on JVCs these days?

[scottrichardson]

51 minutes ago, hopefullguy said:

will you be buying front wides? ie: psa mtm210's.. cant get them here anymore and they are very expensive these days from the U.S.

Yes. Although mine are older models with slightly different tweeters. So I’m not sure how different the newer ones sound.  
 

fortunately my wife works in international logistics and can arrange pickup, customs and shipping etc for me. Actually thinking of asking the admins here about a group buy for PSA as I know a few people here would be keen. I need 3-4 subs so that’s a lot of weight and volume to move. Shipping costs are about $150 per cube per skip but that’s just the shipping, there’s pickup, loading, port clearance, customs/import and of course GST at our end and then pickup locally. 

[betty boop]

22 hours ago, scottrichardson said:

The current room is good, but a shade small if I'm honest, given the two rows of seats, and the depth required for the MTM210 speakers. My back row of seats is awfully close to the back wall, and the side surrounds are quite close to the listener. Accoustically, the bass response around the seats is very uneven, most likely due to the single sub. The bass is extreme at the rear corners of the room, and the back row of seats experiences a very different sound than the front row. The 'directors' chair IMHO should be the front middle seat, but the bass nulls there are prominent.

great to hear of new developments here scott

 

scott, probably hard to tell from the picture but it sure looks like with the current room, front row is in the middle of room ? ...which unfortunately is plagued usually with nulls...

 

usually in most rooms you put the "directors chair" where is best optimum in the room and really dont care too much about the rest it is what it is ...

 

re bass and trying to completely even it out across the room will cost an absolute fortune, create major headaches with multiple subs beyond 2 is challenging and be near darn impossible to achieve and not really totally necessary in my opinion. Id totally expect bass gains in the rear corners too..you can fix those with bass traps but they themselves would be MASSIVE in both size and cost ...

 

I'd work back from screen size..... what are your new room dimensions ? id consider main viewing / listening position at the 2/3rd room depth ...often works... if indeed going 1m longer ... would that be 6.4m depth so sit at 6.4m and would still leave 2.2m for rear row... which should be more than adequate to fit in ? 

 

re the heights... definitely put in ceiling rather than on wall as helps to have these above you... id also pass on front wides with a large scope AT screen you are going to have pretty good width of image sound wise anyways id suggest. will get more gains i think with 6 heights and id go the Ts/VOG + Ch option can do with the marantz and will be to benefit of dts-x pro/neural X, auro 3D imax etc all of which your marantz would support and with 14ch of amplification well kitted out for it ... 

 

I know seem to be a bit PSA focussed... but no support in au anymore... is it worth speaking to krix ? they would do a pretty awesome krix wall I think  and have all the speakers you'd ever need to pick from to complement for the rest. they work extremely well with elektra too ...plus could get some local advice on room setup  to suit...

 

[davewantsmoore]

19 hours ago, niterida said:

Not at all - for 2 rows of seating the 3rd row of height speakers is recommended - can then put the rear heights further back behind the rear row instead of in front.

Plenty of room for wides

 

There is no way for either of these, which come close to following the dolby guidelines.

 

The result of adding them (and not following the guidelines) will be "more sound".... and to the untrained listener this may sound "more immersive" ... and seem like a "better experience".

 

.... but what it does, is distort the direction of where sounds are coming from.    The surround decoder / calibration has no way of knowing "which direction" sounds are coming from.... only their level and frequency response.

 

For example, this will mean that for at least some seats... the wides will be at the wrong angle.   This will mess up the placement of sounds.     If the room were much wider, then the wides could be placed in a location where they were within the angle range for all seats.

 

The same goes for the heights..... Adding more speakers may take the perceived "immersion" up a notch.....  but exactly the same result can be achieved with less speakers that are laid out right, and calibrated right.....  but the key is "laid out right and calibrated right".   The decoder can make a sound come from the exact location where one of the extra speakers would have been......  but only if the speakers are in the right place, and calibrated exactly.

 

19 hours ago, niterida said:

moving your seating a bit further back to keep your ears out of the midpoint

I would not worry about this.... given the number of sound sources <300Hz there will not be the cancellations that you get with just 2 sources.

 

What I would suggest (although it likely competes with video) is to sit as far forward in the room as you can get away with - within the dolby angle guides, and of course, with viewing distance  (this may also, happily, impacy the screen size requirement downwards).

 

19 hours ago, niterida said:

And maybe move your height speakers out a bit wider so they are outside the outer seats.

The would seem to also violate the dolby placement rules (0.5 to 0.7x wide).... but it's hard to say for sure without exact measurements of things.

 

The crux is that all of these recommendations/rules depend strongly on having a well laid out speakers.    With correctly laid out surround and back-surround channels.... then I would lean almost towards locating the height speakers closer to the centre of the room (away from the walls) as possible (ie. 0.5x wide, rather than 0.7x).

 

Similarly with the front/rear spacing of the heights..... unless the surround channels are a good distance (which they're not here) .... then the heights need to go closer together .... to the point that less heigh speakers give the same result (actually  you'd expect a better result given less reflections from nearby walls (which create strong peaks/dips in the respone which can't be EQed out).

 

13 hours ago, scottrichardson said:

with the MiniDSP in action?

Depending on where you plan to place them.... I'd just start with using your processors calibration  (unless the subs need the MiniDSP for EQ or crossovers, or something).    A miniDSP will give you the benefit of being able to seperately calibrate all four subwoofers (where as your processor will only do two!?)

 

13 hours ago, scottrichardson said:

Thank you. Yeah I think the Atmos channels will be wider than that. I will post a proper room mockup once we have more talks with the trades guys. I almost have room for wides already in my current room so I should be fine with an extra meter in each dimension!

Are you following the dolby placement rules?   (Yes, they're not the easist thing to interpret)

 

If you have a surround and a front that are placed correctly and calibrated .... the the "wide sound" will be rendered correctly. 

 

If you have a wide speaker which is placed wrong... the wide sound will be rendered wrong.

 

... but if you have speakers which is not laid out / calibrated correctly ...... then both (with, and without, wides) will both sound "wrong" (the "wide sound" won't be where it supposed to be) .... and so, it's common that the addition of more speakers sounds like "zomg! more sound, more immersive".

 

I hope that makes sense ..... but at the end of the day, fitting speakers well into a small room, is close to an impossible task.... I would just recommend don't break the Dolby rules where you don't have to.     Put the listener far from the back wall..... and put all speakers as far from "other walls" as you can, while staying within the angle guides.

 

1 hour ago, betty boop said:

which unfortunately is plagued usually with nulls...

The nulls are below the crossover frequency to the subwoofers.... and so you can address this by placing the subwoofers to counterract it.

 

To be fair, I wouldn't choose to sit perfectly in the centre either (move forward, or back) .... but you can see the attached pic, showing just a quick and dirty sim (I took 5 seconds to place the subs) with no EQ, that it's not the problem most thing...... and that advice normally comes from "stereo setup giudes", where you can't move the sources.

 

1 hour ago, betty boop said:

re bass and trying to completely even it out across the room will cost an absolute fortune, create major headaches with multiple subs beyond 2 is challenging and be near darn impossible to achieve

The pic I posted, as with 4 subwoofers and no EQ  (the black line is the total) .... for sitting the centre of the room (the worst).

 

His intended processor (AFAIK) can EQ two subs.... so just connect two of the four woofers to each output, and let the processor do it's thing. 

 

You could get a galactic jump forward by putting some sort of extra 4 way calibration in between the processor subwoofer out (like a minidsp with dirac live, or something) .... and then letting the processor "calibrate" it as just "one big subwoofer".

 

... but the point is that you don't need that. ... its not hard at all, assuming that someone has the space to put 4 subwoofers in "uneven" positions.   Of course, if you can't fit 4 woofers, or you can but they "have to go there, and can 't fit anywhere else" .... then it's tough, and could even be detrimental.

 

1 hour ago, betty boop said:

I know seem to be a bit PSA focussed... but no support in au anymore... is it worth speaking to krix?

 ... with the option of smaller boxes too.   The SPL available from PSA, couldn't imagine is required (but, hey, maybe it is.. shrug).

[Guest niterida]

45 minutes ago, davewantsmoore said:

 

There is no way for either of these, which come close to following the dolby guidelines.

 

The result of adding them (and not following the guidelines) will be "more sound".... and to the untrained listener this may sound "more immersive" ... and seem like a "better experience".

 

 

Dolby Guidelines are to put the wides between 50-70deg - pretty much exactly where he has them.

 

Dolby Guidelines are to have the front and rear heights between 30-55 deg elevation and the middle heights at 70-110deg.

So he could put top middles above him and leave his 4 heights where they are or move them further forward/backward and still be within spec.

 

Its not just about getting more speakers - its about getting more even coverage and proper placement across multiple seats and across multiple rows.

[Guest niterida]

55 minutes ago, davewantsmoore said:

I would not worry about this.... given the number of sound sources <300Hz there will not be the cancellations that you get with just 2 sources.

Yes but you will possibly get the biggest nulls below 80hz which will be very noticeable and won't be corrected by multiple speakers. Multiple subs will be able to correct it, but putting your seating position where it doesn't need to be corrected is always going to be better option IMO.

[Guest niterida]

1 hour ago, davewantsmoore said:

The would seem to also violate the dolby placement rules (0.5 to 0.7x wide).... but it's hard to say for sure without exact measurements of things.

Maybe but you still want Left speakers to be on your left - or at least as far to the left as possible if they can't to your left.

Edited July 30, 2021 by niterida

[Quark]

3 hours ago, scottrichardson said:

That sounds great! Worst case scenario is I just lump the lumen drop until new laser models come out. 
 

what’s the resale value like on JVCs these days?

 

Resale has been good, but when the laser models come out there's been speculation that the N7 will become the base model and cop a price drop, which obviously wouldn't help your resale.

[davewantsmoore]

36 minutes ago, niterida said:

Maybe but you still want Left speakers to be on your left

Ummm.... Yes, of course.

 

The dolby guide is telling you how far left (or right) of the centre line that the ceiling speakers should go....  putting them "outside the outter seats" .... is at a rough look, way outside the spec.....   and is also generally disadvantagous as it will put them close(r) to the sidewall.

 

42 minutes ago, niterida said:

Yes but you will possibly get the biggest nulls below 80hz which will be very noticeable and won't be corrected by multiple speakers.

? 

 

Will and won't are absolutes, and it depends on the specifics..... but you can see from my pic, that even sitting perfectly in the centre of the room, that you can get a flat response.    The reality is that you get nulls below 80Hz anywhere in you sit in the room..... but they also extend up to 200hz or more in a small room.

 

42 minutes ago, niterida said:

Multiple subs will be able to correct it, but putting your seating position where it doesn't need to be corrected

As I said.... you only need to break out a room/mode simulator to see that there is basically no such place.

 

Sure, there are bad places and better places to sit...... but the point was to optimise the seats for their positioning relative to the screen, the speakers (vs the dolby rules), as these are just not fixable any other way.

 

Quote

So he could put top middles above him and leave his 4 heights where they are or move them further forward/backward and still be within spec.

Yes, they would need to move some.

Yeah. You might even get in 6....

 

 

[scottrichardson]

4 hours ago, davewantsmoore said:

but you can see from my pic, that even sitting perfectly in the centre of the room, that you can get a flat response. 

 

I don't seem to see your pic anywhere on here? Did it attach/upload OK?

 

Quickly - many thanks to all of you for the replies and this discussion. I will come back to it after dinner!!

[davewantsmoore]

2 hours ago, scottrichardson said:

I don't seem to see your pic anywhere on here? Did it attach/upload OK?

No, I didn't. Whoops.

 

The pic might be a it hard to see/decipher .... but there's 4 subwoofers (plus 5 speakers) ... and the listening position is exactly in the centre of the room.

 

It's almost a bit off topic, sorry - but it was to demonstrate a specific point.

 

Edited July 30, 2021 by davewantsmoore

[Guest niterida]

8 hours ago, davewantsmoore said:

Ummm.... Yes, of course.

 

The dolby guide is telling you how far left (or right) of the centre line that the ceiling speakers should go....  putting them "outside the outter seats" .... is at a rough look, way outside the spec.....   and is also generally disadvantagous as it will put them close(r) to the sidewall.

 

0.7 room width will put them outside his seats and away from walls according to his plans.

 

8 hours ago, davewantsmoore said:

Will and won't are absolutes, and it depends on the specifics..... but you can see from my pic, that even sitting perfectly in the centre of the room, that you can get a flat response.    The reality is that you get nulls below 80Hz anywhere in you sit in the room..... but they also extend up to 200hz or more in a small room.

 

As I said.... you only need to break out a room/mode simulator to see that there is basically no such place.

 

I said "will possibly" which is not absolute. 

I also said "below 80hz won't be corrected" which is an absolute but is also pretty much true since speakers (not subs) won't be adding much (if anything) below 80hz.

 

You are correct about there being no place in any room that is not affected by at least one mode. I should have said the 1/3 distance needs the least amount of correction (and actually that isn't true since I believe it is actually at 38% room length that needs the least correction but 1/3 is easier to suggest).

 

8 hours ago, davewantsmoore said:

Sure, there are bad places and better places to sit...... but the point was to optimise the seats for their positioning relative to the screen, the speakers (vs the dolby rules), as these are just not fixable any other way.

 

Yes ideally you would determine the screen and seating arrangement first, then add the L&R speakers and THEN determine the room size. Most people do it the other way around due to already having the room, or not having the knowledge when they draw the room up.

 

8 hours ago, davewantsmoore said:

Yes, they would need to move some.

Yeah. You might even get in 6....

 

 

No they wouldn't have to move and you would definitely get 6 in.  

4 heights at 45 is the recommendation, and for 6 the 4 heights can stay at 45 and just add a pair in the middle. 

It may not be necessary but it is certainly do-able and within specs.

 

Your pic shows a room with 4 subs - I don't think we have gone that path in his room yet have we ? He did query in his OP about more subs - so yes more subs is required !!

So sure you can sit anywhere with enough subs and enough acoustic treatment - in fact that is exactly what I have done in my room - I sit at 42.5% of room length (I was one of those people that designed the room before I had the knowledge ) and have copious absorbers (and building 2 massive bass traps for the 4 rear corners) and currently have 4 subs with more planned. It sounds good but I definitely have a 55hz peak (which I think is floor-ceiling mode) which I plan to eradicate with a pair of subs mounted at half room height.

 

 

[davewantsmoore]

12 hours ago, niterida said:

Your pic shows a room with 4 subs - I don't think we have gone that path in his room yet have we ?

No.... it was only to demonstrate a point.

 

 

12 hours ago, niterida said:

more subs is required

It's one way the attack the issue... especially if multiple seats.

 

 

12 hours ago, niterida said:

So sure you can sit anywhere with enough subs and enough acoustic treatment

FWIW, there are no LF absorbers in that pic.

 

... but more importantly that if you break out a simulator, you will see that there really aren't (m)any good places to sit.   There are issues everywhere... they just move.

 

12 hours ago, niterida said:

pair of subs mounted at half room height

Yes!   This is often overlooked.  

[scottrichardson]

Thanks all.

 

So I have a fairly sound understanding of how to calibrate, time align and EQ multiple subs. I have already run REW and have my MiniDSP setup to give me the best possible bass in my middle front seat in my current theatre. 

 

The plan is DEFINITELY to add more subs for the new room, and more than likely it will be a total of 4 subs. 

 

Looking at 5.4m wide x 6.5m deep, and avoiding seating at the middle of the room. I'll be aiming to place the seat rows between primary and secondary nulls as best I can, and mitigating the primary half-width null from left to right wall (centre seat in each row) by having two subs equidistant from the sides of the front wall, so I can create a 'virtual' sub in the centre of the wall which should nullify the null - at least according to Steve at Home Theatre Gurus!

 

I have run the room model in REW with 4 subs, and it doesn't seem to matter too much whether they are in the corners or the 1/4th positions. Although it depends on what subs I use since my current model has dual opposing 18" drivers which fire out to the sides.

 

Based on the conversation so far, my biggest concern should be the issue of brightness while trying to maintain a 165" screen that is acoustically transparent. If that is the case, then how much smaller should I be going down to, and how far back should the projector be mounted to get the most light possible so that my brightness is as bright, or brighter than what I have now? As mentioned, I'm already at what I'd consider the limit for brightness with my 165" screen. I believe there's also issues with moving a projector slightly closer to the screen if you're using an A-lens as this increases the pincushion effect (which I do get a little bit of now).