[zybar]

Interesting thread, and sorry to miss this while I was away on vacation for a few days.

I don't have too much to add at this late date, but I encourage people to set up a controlled test if possible, to fairly compare absorption versus diffusion. I haven't done that for the ceiling reflection points in my living room HT because it's a pain with my high angled ceiling. But I did do a carefully controlled test at the side-walls, and absorption won there handily.

I assume that speakers having a narrow dispersion pattern are affected less by either absorption or diffusion. And of course speaker dispersion varies both horizontally and vertically. Speakers that don't send very much sound upward probably don't need anything on the ceiling.

--Ethan

I don't have any measurable data supporting this assertion, but I am guessing that my speakers (Vandy 5A's) would benefit from something on the ceiling.  At the last few shows, Richard Vandersteen brought room treatments for all the first reflection points and used diffusion on the ceiling.

George

[ctviggen]

I don't have any measurable data supporting this assertion, but I am guessing that my speakers (Vandy 5A's) would benefit from something on the ceiling.  At the last few shows, Richard Vandersteen brought room treatments for all the first reflection points and used diffusion on the ceiling.

George

George, you could probably do a test, since you have diffusion already behind you.  Take those diffusive elements out of the room and listen for a while.  Then put one of the diffusive elements "on" the ceiling and see what the results are.  The hardest part will be figuring out how to get the diffusive elements up there temporarily.

I don't have any diffusive elements to test, and my room is still under construction (drywall in, but still needs to be painted and the wainscoting put in). 

[Big Red Machine]

I haven't moved the Gik diffusers behind me or just back of my head on the side walls.  I brought the RT Near Diffusors up behind the speakers in place of absorber panels and added the side diffusors and for right now, just 2 Auralex T'fussors overhead.

Without measurements before and after I can't show anything visually, but I am very happy I did this.  As woodsyi mentioned, the decay is much longer and was something I never knew I missed.  I wouldn't say my room was overdamped and even now the bass is reasonably trapped but could stand some more as you walk around the perimeter.

My soundstage is deeper than I ever had in the room and is wall-to-wall wide now.  The music fills the room as I would expect a live venue to fill and I have bass from behind me now in some tunes.  I've been running the SB on Random to rediscover my music files.

[zybar]

George, you could probably do a test, since you have diffusion already behind you.  Take those diffusive elements out of the room and listen for a while.  Then put one of the diffusive elements "on" the ceiling and see what the results are.  The hardest part will be figuring out how to get the diffusive elements up there temporarily.

I don't have any diffusive elements to test, and my room is still under construction (drywall in, but still needs to be painted and the wainscoting put in).

Not sure if you have seen the size of the Realtraps Diffusors, but they are quite big (24x48x6 and 26 lbs) and definitely not something to just take down from the current location and temporarily relocate them to the ceiling. 

Here is a picture of them in my room:



George

[Ethan Winer]

But is it possible that other rooms can give different test result?

Sure! I'm very open about explaining that my few tests were done in small rooms. One was my living room which is 25 feet front to back by 16 feet wide. The other was a smaller room, 17 feet long by 11.5 wide. The difference was so obvious, with absorption winning by a landslide, I'm always surprised when people say they prefer diffusion. But maybe their room is wider, and of course personal taste is a factor.

--Ethan

[Ethan Winer]

Ethan, care to let me borrow some diffusers? 

That's not out of the question, and you're always welcome to visit me here to compare absorption versus diffusion. I just got a new huge (159 inches) video screen and it's awesome.

--Ethan

[bpape]

Uh-oh.  You've gotten sucked into the HT thing Ethan.  It's an even bigger money hole than audio sometimes 

Bryan

[ctviggen]

Not sure if you have seen the size of the Realtraps Diffusors, but they are quite big (24x48x6 and 26 lbs) and definitely not something to just take down from the current location and temporarily relocate them to the ceiling. 

Here is a picture of them in my room:



George

George,

How are those held up? 

I think two adults could easily hold a 26 pound diffuser up for a test.  (As an aside, does 26 pounds seem heavy to you?  As someone who is currently lifting 4x8 sheets of 5/8 inch, fire rated drywall, 26 pounds would be great to hold up instead.  With two people, that's 13 pounds per person.  I think my drill is heavier than that, and I hold it up for many minutes.)  Getting them down might be a problem, obviously.  And, you should test the system with the two adults in the room before putting up the diffuser for a more accurate test.

[ctviggen]

That's not out of the question, and you're always welcome to visit me here to compare absorption versus diffusion. I just got a new huge (159 inches) video screen and it's awesome.

--Ethan

159 inches?  I'm waiting to put up my 92 inch screen.  159 must be very immersive.

[Ethan Winer]

Uh-oh.  You've gotten sucked into the HT thing Ethan.  It's an even bigger money hole than audio sometimes 

I've had a "video" setup for years. I started with a 65-inch Mitsubishi RPTV many years ago, which I still have (behind the screen) that still works great for watching TV and older low-res DVDs. Then a year ago I got a 110-inch screen and Mitsubishi projector and Blu-ray player. I was sure 110 inches would be huge! Alas, for an entire year Elli and I fantasized about a much larger screen. So a month ago I sold the 110" screen and got this monster that's 12 feet wide:



Our couch is ten feet from the screen, so it's like being at an IMAX theater. "Immersive" is an understatement.

--Ethan

[John Casler]

Sure! I'm very open about explaining that my few tests were done in small rooms. One was my living room which is 25 feet front to back by 16 feet wide. The other was a smaller room, 17 feet long by 11.5 wide. The difference was so obvious, with absorption winning by a landslide, I'm always surprised when people say they prefer diffusion. But maybe their room is wider, and of course personal taste is a factor.

--Ethan

Hi Ethan,

I think the "key" word is PREFER.

Much of the time, room treatments are about "shaping" the sound to a "preference" and not about creating an acoustic absolute of the original event or recording.  And many times there IS no absolute sound.

I too find diffusion a strange practice for HT, but if the goal is to shape and create a sonic that the owner likes or prefers, it is, or can be successful to that application.

And Bravo on the 159" screen.  I have a 120" and couldn't imagine going smaller for my viewing "preferences" (I sit 5-8th row center when in theaters to be "IN" the film, not outside looking in)

So HT has more lattitude in many ways than the sonic engineering of a 2 channel event where "any" room related distortion could be considered an impingement of the the absolute.

Even the speaker types often used show this.  Dipoles, bipoles, Horizontal Centers, wall mountings, differing heights, non-equidistant placements, all cause changes to the sound produced, and sometimes "prefered".

Makes the hobby "personal", much like customizing your auto, house, wardrobe or whatever.

[Ethan Winer]

^^^ Absolutely agree on this being all about preference John. Hey, that's what tone controls are for too.

--Ethan

[Charles Xavier]

I've had a "video" setup for years. I started with a 65-inch Mitsubishi RPTV many years ago, which I still have (behind the screen) that still works great for watching TV and older low-res DVDs. Then a year ago I got a 110-inch screen and Mitsubishi projector and Blu-ray player. I was sure 110 inches would be huge! Alas, for an entire year Elli and I fantasized about a much larger screen. So a month ago I sold the 110" screen and got this monster that's 12 feet wide:



Our couch is ten feet from the screen, so it's like being at an IMAX theater. "Immersive" is an understatement.

--Ethan

Can you tell us what equiptment you use 

[Ethan Winer]

^^^ This is not the first time someone has asked. I should make a web page somewhere detailing everything. I recorded a nice walk-around video of the current setup last week, so maybe I'll make a formal video. In the mean time:

The video is a little complicated because I have a 65-inch Mitsubishi Rear Projection TV as well as the new 159-inch projector screen with Mitsubishi projector. (We kept the TV for watching standard definition TV at a more practical size.) My receiver switches video to the RPTV as well as all audio, and a separate HDMI switch handles the projector video.

I have a consumer type Pioneer receiver that routes the sound from all the devices: Cable box, Blu-ray player, 5.1 sound card on my Dell laptop, and an old VHS recorder. I use the digital audio outputs from the cable box and Blu-ray player, and both digital (stereo) and analog (5.1) from the laptop which has a Presonus FireBOX sound card. I've done a few surround mixes with my laptop, which is why I bought the FireBOX rather than a regular stereo sound card. As with all modern receivers, this one decodes Dolby and DTS, and does bass management splitting the audio between the five main speakers and subwoofer.

The sub is a killer. It's an SVS PB12-Ultra/2 which has twin 12-inch drivers and can be tuned to go down to 16 Hz. I have it set for 18 Hz as the -3 dB point because that gives a little more overall output level yet is still plenty low. The main speakers are Mackie 624s, sold mostly as pro studio monitors. They're bookshelf size with a 49 Hz -3 dB point, but that's plenty low when used with a sub.

There are 55 various RealTraps panels. Most are bass traps, but five are mid/high frequency absorbers at reflection points, and there are four diffusors on the rear wall. Yeah, I really should make a video showing all of this.

--Ethan

[bpape]

And everyone should have a wife as tolerant as yours Ethan.   

Bryan

[Ethan Winer]

I met my wife (in 1980) when she was one of my recording students. So she enjoys high quality sound as much as I do. The good news is more people these days have dedicated rooms, where they can do whatever they want without spouse objections. Versus my HT which is also our living room.

--Ethan

[Charles Xavier]

For a man of your caliper, I am glad and suprised that you have a very down to earth and average everyday system

[ted_b]

For a man of your caliper....

You might not have meant this but it's a nice miss..being that Ethan is all about measurements.   

[Nyal Mellor]

I personally like combination absorber / diffuser products at the first sidewall reflection points. Either RPG BAD, BAD Arc, or one of the similar products.

A similar effect can also be realized through interleaving pieces of absorption with the reflective wall surface by using 6" thick strips of absorber or small squares.

[arthurs]

I personally like combination absorber / diffuser products at the first sidewall reflection points. Either RPG BAD, BAD Arc, or one of the similar products.

A similar effect can also be realized through interleaving pieces of absorption with the reflective wall surface by using 6" thick strips of absorber or small squares.

I concur with this.  We implemented BAD ARC's on the side walls when we upgraded my room and it is an excellent product.