65 replies to this topic

[Chicken Man]

I don't use an AT screen at all but a painted MDF screen and it does do an excellent job for its outlay, but of course it can only compromise when it comes to the presentation of the 'audio image' of the movie.

I use the term 'audio image' for that is what it is, and unless the 'audio image' and the 'visual image' are aligned the whole movie presentation lacks coherence. Also, presenting a broad sound stage with all the drivers acoustically aligned in the same acoustic plane also helps to camouflage poor room acoustics. Curving the supporting baffle again goes to aiding sound projection into the main veiwing area, I found this even when using a slightly curved painted screen.

The truth is if one wants the best visual/acoustic alignment without the hassles of speaker placement and all the incidental illumination of such boxes one cannot go past the AT screen, there is no practical way one can avoid not using it if one wants to get one's movies coherent.  Something I have yet to do myself.

C.M  

[SDL]

I'm confused smx say they have patented weave screens with the highest gain for a weave in the market at 1.16 and for a 4D at .88. They confirm also that other weaves are as low as .83 - yes again advertising but it seems a lot of misinformation or at best confusing information around. Like the 1 v 3 amplifiers, the need for black backing for some screens due to light loss. It's a minefield at times.

[minty]

With possibilities such as this, it makes me wonder, despite the extra cost and effort, why more people don't go with an AT screen if they have the space. I know i made a mistake not going ahead with one when i had the chance. How cool would that be to look at whilst sitting back and listening to some music? Just walking into this room would instill a sense of knowing "this is going to be good".

Edited by seatonrocks, 07 June 2012 - 03:27 PM.

[SDL]

Definitely was a no brainier for me, while some do like seeing their toys on show my concept was to see nothing but the picture and hear the sound and that is what I got. I thought about some lighting behind the screen like that but figured I would only turn it on once in a blue moon so never bothered

[Chicken Man]

In my case, I've bauked at the price of a good AT screen.
Surely the screen material can't be that difficult to make ?

Even a thin, opaque flat-white plastic sheet (without any wrinkles) if tightly stretched by the support should have little absorption of the higher frequencies above 10 Kc/s, maybe the Tone Controls could give some lift there if needed.  With the L/F crossover set at or above 100/cs there should not be any movement of the screen material at all. I would give it a try if I could find something suitable.


C.M

Edited by Chicken Man, 07 June 2012 - 06:38 PM.

[oztheatre]

SDL, on 07 June 2012 - 12:34 PM, said:

I'm confused smx say they have patented weave screens with the highest gain for a weave in the market at 1.16 and for a 4D at .88. They confirm also that other weaves are as low as .83 - yes again advertising but it seems a lot of misinformation or at best confusing information around. Like the 1 v 3 amplifiers, the need for black backing for some screens due to light loss. It's a minefield at times.

There is no patent, I'm that's just marketing and a deterrent... It is the exact same material we use here. Other screen mobs are also using it.
It yields a positive gain because it's polyester with a vinyl coating. So even with the holes in it, because of the vinyl coating, you get a 1.16 gain. I went as far as getting mine tested by an ISF calibrator in Sydney some years ago - video display calibrations. I didnt worry too much about the audio side as I don't have a chamber to properly test it in and I never went down the isf or thx certification route because it's just such a massive outlay and I like to keep my prices where ordinary folks can buy them.
Here's the PDF, it's not on my site at the moment, not linked for some reason (computers!) http://www.ozts.com....est_results.pdf

[SDL]

Don't get me wrong, I'm actually glad you are able to offer such a great screen at such good prices here in Oz. Mine has THX certification and yes it means it cost more, but I agree that doesnt mean it is necessarily better than one that doesn't as paying for certification is a large expense that has to be passed on. My only real point is that there is good at screens, both microperf and weave, and also a lot of ordinary ones out there, however the information being passed about is misleading and it helps to actually see them and try them. I was lucky when buying mine that I was able to view a few before making a choice, but by no means was my demo exhaustive and I'm sure there are plenty of good ones out there....but boy am I still happy every time I watch mine.

[SDL]

Viewed the PDF that is interesting results.

[oztheatre]

SDL, on 07 June 2012 - 09:12 PM, said:

Don't get me wrong, I'm actually glad you are able to offer such a great screen at such good prices here in Oz. Mine has THX certification and yes it means it cost more, but I agree that doesnt mean it is necessarily better than one that doesn't as paying for certification is a large expense that has to be passed on. My only real point is that there is good at screens, both microperf and weave, and also a lot of ordinary ones out there, however the information being passed about is misleading and it helps to actually see them and try them. I was lucky when buying mine that I was able to view a few before making a choice, but by no means was my demo exhaustive and I'm sure there are plenty of good ones out there....but boy am I still happy every time I watch mine.

I bet you're wrapped with your screen. It's no doubt a brilliant piece of work. They were the ones who started this whole thing.
Yes, seeing them in action and in this case with AT screens, listening to it's performance will allow the end user to feel more confident in their purchase.

I wish I could go down that certification path but it truly is an huge huge expense. The Australian market is much smaller too so recouping those costs would either take years or by putting prices up considerably which I won't do.

[minty]

Richard, do you have an AT screen setup in your Gold Coast premises, I'll be holidaying up there shortly and would love to check it out if you do?

[oztheatre]

seatonrocks, on 07 June 2012 - 10:43 PM, said:

Richard, do you have an AT screen setup in your Gold Coast premises, I'll be holidaying up there shortly and would love to check it out if you do?

No, not yet, only evo3d scope setup with the x70. The new showrooms will take about 3 months at the rate I'm going..

[MarkTecher]

oztheatre, on 06 June 2012 - 09:59 PM, said:

So ideally then, people should be using a baffle with free standing speakers also?

The baffle turns "free standing" speakers into infinite baffle speakers but not all speakers are suitable - ie rear ports.

oztheatre, on 06 June 2012 - 09:59 PM, said:

An AT screen with a screen wall baffle is going to sound better than a non AT screen with no baffle. I gather we're talking about absorption and diffusion treatments to act in a similar way to a baffle with an AT screen?

If the baffle is designed correctly, it harnesses and redirects the speaker energy into the room.  You even get measurable gain in SPL.  The treatments are to prevent HFs bouncing between the baffle wall and the back of the screen.  Even though it is "AT", HFs still reflect.    

oztheatre, on 06 June 2012 - 09:59 PM, said:

What about energy lost at the rear of the speakers? or is this a non issue?

Many free standing speakers suffer diffraction issue and the baffle wall actually stops that.  Of course to get this to work, the cutouts need to fit firmly around the speaker and any gaps need foam stuffed inside.

[SDL]

A baffle wall done incorrectly or with the wrong speakers does more harm than good. Sounds bouncing around uncontrolled blur the image rather than help it

Edited by SDL, 08 June 2012 - 01:43 PM.

[:)]

I agree you'd want purpose built speakers designed with that kind of setup in mind. A lot of conventional speakers designed to operate in free space or with reflective wall behind soundwise would be completely killed in that arrangement

[Elill]

Yes and no, have a read on Toole about it.

Some say there are issues with baffle reflections etc, but in my experience (I've done it with 4 sets of speakers) all that is needed is a little EQ to deal with the bass boost issue. If the tweeter is any good then its generally ok.

Edit: I'd treat the front of the baffle anyway (as you would/should most front walls, in most cases)

Edited by Elill, 08 June 2012 - 03:21 PM.

[Elill]

MarkTecher, on 08 June 2012 - 01:28 PM, said:

the cutouts need to fit firmly around the speaker and any gaps need foam stuffed inside.

Then get black duct tape and cover that (the foam/insulation/whatever) as well

[Chicken Man]

There could also be the problem with 'baffle step' compensation (diffraction loss) being upset by the increased baffle size.

Loudspeaker cabinets having narrow front baffles require baffle step compensation in the order of 3 - 6 db to help compensate for the loss in sensitivity at low bass frequencies when the radiation pattern changes from 2phi  to 4phi. Some manufacturers only compensate for 3 db loss, others using higher sensitivity drivers compensate for 6 db loss, so expect a low frequency boost particularly if the baffle size is quite large.

I see 'Elill' has just mentioned this problem before my posting this.

C.M

[:)]

Completely F's up the imaging has been my experience when start treating areas behind speakers own baffle or if changing the baffle from what design based on. The baffle of a speaker itself has massive effects on a speakers imaging. Why makers like b&w go with no baffle on their tweeter. Eq doesn't change any of that !

[Chicken Man]

Yes Al, but it all depends on how you arramge the new surrounding baffle. If the 'new' baffle extension is large and slowly curves away from the speaker's front baffle the diffraction effects seen by the tweeter and the upper midrange should largely be negated.

But personally I think that is a whole lot of effort to go to for a minimal outcome, then one still has to deal with the added boost in bass response, more tweaking with the crossover. The added baffle size actually turns the loudspeaker into a less refined version of itself. It's hardly a convincing argument to go to all that trouble only to find little improvement if that.

Edit : You will likely hear a difference ....but is it better ?  I think not

C.M  

Edited by Chicken Man, 09 June 2012 - 12:53 PM.

[:)]

I agree CM,

with regard diffraction, what have seen from linkwitz probably shows well the complexities,

http://www.linkwitzl...diffraction.htm

also with speakers his work on directivity is very interesting,

http://www.linkwitzlab.com/rooms.htm

with box speakers and how they radiate, this is where the baffle can hugely impact.

[Chicken Man]

:), on 08 June 2012 - 04:40 PM, said:

I agree CM,

with regard diffraction, what have seen from linkwitz probably shows well the complexities,

http://www.linkwitzl...diffraction.htm

also with speakers his work on directivity is very interesting,

http://www.linkwitzlab.com/rooms.htm

with box speakers and how they radiate, this is where the baffle can hugely impact.

It is quite amazing how dedicated he is in pursuit of this hobby of speaker design and the wealth of knowledge he shares.

I,for one have learned a great deal from his analysis in speaker design, he and Troels Gravesen.
He and Troels have contributed a great deal to the DIY speaker community and ought to be more widely acknowledged.

http://www.troelsgra...er_Projects.htm

C.M

[SDL]

I think it requires a bit of engineering and knowledge of sound to do it properly.

[oztheatre]

SDL, on 08 June 2012 - 06:57 PM, said:

I think it requires a bit of engineering and knowledge of sound to do it properly.

I agree. That's why I'm doing Krix speakers, they're hands on and can engineer any room for any application.
The linkwitz site has a plethora of information there. What a nice man to give so much of his knowledge.

[MarkTecher]

Chicken Man, on 08 June 2012 - 03:54 PM, said:

Edit : You will likey hear a difference ....but is it better ?  I think not

Then I invite you to bring any program you like and listen to my set up.

[Prior]

MarkTecher, on 08 June 2012 - 08:23 PM, said:

Then I invite you to bring any program you like and listen to my set up.

I'm sure your set up sounds great Mark, but you wouldn't be able to do an A/B test, as I would imagine the baffle can't be removed?

Cheers,

Chris