Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Restaurant at the End of Universe Hitchhikers - Meridian Equipment Building a new HT room in huge barn

azazel,

first of all: I envy you for being able to turn such a big room into a HT! It surely is a lot of work (I know from own experience with my HT).

If I understood you correctly you are still in the process of remodeling the barn. Use this advantage well and consider reshaping the walls and ceiling!

Why that? Well, if your walls are parallel then sound gets reflected back and forth with standing waves building up (can be a BIG problem). You might want to google "standing waves" in connection with sub woofer placement and you'll find tons of information if necessary.

Next thing to consider is that if possible you may want to "tilt" all walls inwards, meaning the room gets wider behind you than in front of you with the walls being vertical. Also you might want to lower the ceiling in front of you and raise it behind you.

Of course you don't actually have to move the walls. You could put additional bricks etc. at the inside of the room. It would stay rectangular at the outside but be cone shaped inside.

Another important thing to consider are the room modes = length of the 3 main dimension (length, width, height). Again google "room modes" or "standing waves" and you will see that certain ratios of the 3 length values are really bad. My HT for example is as long as it is wide, which gives you standing bass waves of a certain frequency (depending of the exact measurements). It took me a lot of effort to eliminate that (placement of sub, building and placement of bass trap, using an equalizer to filter out a tight frequency band).

I wish you good luck with your project. Please upload a few pictures as I am sure there are more folks than just me interested.

Thomas

Hi Thanks for your thoughts. Do you think that the soft walls and ceiling that I am building will still have standing wave reflecting back and forth? I thought that the studds and ceiling joists with the rockwool between them would make a good non reflective and refractive room. I will have carpet on the floors and refractors on the walls to scatter sound. One end of the barn (the screen and main speaker end) may be curved with really thick rockwool walls covered in fabric.

Its looking like I will have a 568 and four 557 amps. One each for frontleft, right and center, and one for rear left and right. Does anyone bother with side left and rights?

BTW, Im looking for a nautilus htm1, the three way center speaker B&W used to make.

azazel,

I am no expert on room acoustics, but I think that the rockwool will absorb a lot of energy thus decreasing the possibilities of standing waves. Just understand that this is an effect for very low frequencies and that those low frequencies have a lot of power. So it takes a lot of rockwool to absorb the energy and not let it reflect back into the room where it might form a standing wave. There are plenty of online calculators where you can enter the exact dimensions of your room to find out how critical your room might be (I would use the dimensions from one hard surface to the opposite hard surface not counting the rockwool).
Here's one calculator: http://www.bobgolds.com/Mode/RoomModes.htm

High/mid frequencies are a different beast. The surface of the materials becomes a major factor regarding reflection. Say you have 50cm of fluffy rockwool that you cover with thin cardboard, ultra thin plastic foil or a wallpaper: This would take out a lot of the low frequencies but would still reflect much of the high frequencies, because of the flat and dense (although thin) surface of the cover. You can either use a fluffy cover (like felt or fabric) to ABSORB the sound or you can have an irregularly shaped surface to DIFFUSE the sound. Try to incorporate that into your plans on how to cover the rockwool. Standing waves a no problem here.

Regarding your plans for the HTM1 as a center speaker: I was using the 803S with the HTM2 which was a good combination, so I guess the HTM1 will suit your 802 well. BUT: I upgraded the 803S to the 803D and was simply blown away from the diamond tweeter (the increase in clarity was like putting gloss on a picture) and then also upgraded to the HTM2D. Maybe you want to "downgrade" from 802 to 803, but get the diamond tweeter on all 3 speakers (including the center). If you have a chance to listen to the 803D then give it a try.

All the best,
Thomas

P.S. Still no pictures???

Hi Thomas

I havent worked out how to upload pictures yet.

So far, I have done the floor and half the stud walls. Im very busy at the moment with work so I have to do it evenings and weekends.

The fabric I have chosen is natural hessian. Its cheap, coarse has texture and is a loose weave that will allow the sound to penetrate to the rock wool. I might use 100mm rock wool in the ceiling as the ceiling joists are 125mm.

Maybe one day I will try out the 802D speakers. I prefer the build quality of the Nautilus 802 though. Looks to me like B&W have tried to make the 802D more economical. Obviously the diamond tweeter is a big improvement on the design though.

Anyone got opinions on projectors? I was thinking of buying a used one on eBay.

azazel,

the idea with the hessian sounds good from an acoustic stand point, but I am a bit worried that there might be fibers of the rockwool flying around in the room later. Wouldn't that be potentially hazardous to people (lung cancer or allergies)? Might it also be a "dusty" environment that your equipment dislikes?

Regarding the speakers:
I was suggesting a trade-in from your current 802 to the 803D (not 802D) in order to save money. Of course I expect the 802D to be better compared to the 803D, but it's also more expensive. Just a tip that "downgrading" would probably be an improvement due to the tweeter.

Regarding the projector:
1. What kind of projector are you thinking of (i.e. CRT, digital)?
2. Will it be acoustically shielded (i.e. in a separate room/hushbox)?
3. What kind of signal will you feed into the projector and will that signal come from the player, HT amp, an external video processor?
4. What are the necessary cable lengths from source to projector?

Just to give you a few ideas:
1. I just switched from a Barco Cine7 (CRT; >15.000,- EUR 7 years ago) to an EPSON EH-TW 5000 (full HD; <3.000,- EUR). I was fed up with adjusting the convergence permanently and am very happy with the EPSON.
2. In the EPSON there are 2 major sound sources: the fans and the adaptive iris (which is actually louder than the fans). The BARCO was also well audible. I therefore built a hushbox that is mounted under the ceiling with a separate fastening of the projector inside that is decoupled from the hushbox. Now all I hear is a whisper...
3. I feed the HDMI signal directly from the player into the projector.
4. I am using a 15m HDMI cable that costs appr. 300,- EUR.

If I were you I would buy a new projector. First of all you got warranty and prices are quite affordable by now. Having 802 speakers and a crappy projector that was cheaper than the connecting cables would appear silly to me...

Just my 2 cents,
Thomas

I went from a Barco BG808s to a JVC 350. I almost never had to touch the Barco convergence as it was set up mechanically pretty spot on and only needed a small amount of tweak using the electronics. This seems to be the key to CRT consistency of performance.

The JVC, however, is actually superior in performance and much quieter than the CRT. I go from BD via the HD621 to the projector on HDMI.

Hi Thomas.

Im happy with my speakers thankyou. I have lots of other stuff to get so upgrading my main speakers is not a priority, although one day Id like to hear a pair of 802D.

Regarding the projector, I dont know much about projectors and Im reading up on them. I think Id go for a screen about 1.2m x 2.4m. Do I buy a used one on eBay or get a new one? High res or low res? LCD? I havent decided yet. Cable lengths and projector location all depend on the projector when or if I get one. I might get a plasma even. Im inclined to buy a new one so for the warranty and the newer specs.

Its going to take some time before I get the room finished and then furnished.

Whats the best way to wire up two center speakers to a 557 from a 568? Anyone?

Hope you're enjoying my 557!

Best way to wire up two centres is to split the line signal from the 568 to the 557 using a custom made cable. Mark Grant will make you one if you ask him. He made a handful for me and they're excellent. But i used phono cables and I believe you'll be wanting to do it with balanced, so get in touch with him. (www.markgrantcables.co.uk) He offers discounts to AVForums members and hand makes everything.

On Projectors, I have to agree with the JVC concensus. They make some superb projectors. Best around at the money.

The ones to look at if you want to snare a bargain are:

JVC DLA-HD100 - Full HD and outstanding
JVC DLA-HD350 - Replaced the 100 but slightly below it
JVC DLA-HD750 - Replaced the 100, now replaced by 950 & 990

They're all good, and you should be able to buy new at a discount to the RRP as they've been replaced. But don't let that put you off! If it was me I'd hunt around for a 100. Best value and almost identical performance to the ones above. Failing that either of the other two.

Screens, you should be very careful, makes a big difference and can cost as much as the PJ, depending on what you need. If it's a permanent room, then go for a fixed tensioned screen. If you're front speaker is behind the screen you need to specify an accoustically transparent material. If not, then you don't.

You need to keep in mind the distance from screen to PJ, this will determine either the PJ you buy (for it's throw ratio) or where you place the PJ.

Best screens are made by Screen Research and Stewart Filmscreen. Expensive, but worth it.

Good luck and enjoy! Sounds like a wonderful project.

Hi Azazel
'
'Whats the best way to wire up two center speakers to a 557 from a 568?'

Not a good idea to connect 2 centre speakers. I raised this point in the forum about 2 years ago and the expert advice received from Kal Rubenstien was that it was a bad option. He did give the technical reasons why this was so which I have now forgotten and I did not in fact proceed with the dual option but stuck with a single centre speaker. Now irrelevant to me as I have gone all digital with 5200's across the front

Rod

Rodders has a good point. My splitter cables were built to aid bi-amping, but if you plan to use two centres, you'll have in-phase cancellation issues. So you'll have to be careful with placement. You'll also have no discrete control over each speaker as they'll be taking the same signal.

Which speakers were you planning to use to double up the centre, if you're running N802 fronts then an HTM1D would have to be your goal and you might well want to bi-amp this, but you certainly wouldn't need two! :-)

As others have stated, two centres isn't a good idea.

How to wire them up if you do go this route;

Single balanced XLR from 568 to 557.
Run 557 in mono mode.
Connect loudspeakers in series to 557.

680 watts into 8 ohms, 340 watts across each loudspeaker.

This assumes the loudspeakers are 4 ohms nominal.

Steve.

How do you switch a 557 into Mono mode?

It has a switch to switch it into bridged mode, but then the only way to attach two pairs of loudspeakers that way would be in parallel. This would take a 4 Ohm speaker to a 2 ohm load and strain the amp a bit, though it would probably work with a beast like the 557 bridged.