Comments on: Home Surround Sound vs Movie Surround Sound: What’s the Difference?

By: Randy

Randy — Mon, 05 Sep 2011 12:05:15 +0000

Great article Alan. I built my dedicated home theater six years ago and my sound system is from Axiom. The sound is fantastic and does give me that big theater feel. I still love to go the the movie theaters and see movies on the BIG screens. I just enjoy going and I like to see movies on the first day of release. When the movie is released on BluRay I get it and enjoy it again in my theater.

By: Gort

Gort — Fri, 02 Sep 2011 14:27:50 +0000

Thank you Ian for a more even handed response and I agree with your thoughts.

By: Ian

Ian — Fri, 02 Sep 2011 14:21:30 +0000

The fact is that everyone here is technically correct. An acoustically transparent screen, like we have used for blind listen testing for years, will not impede the performance and horn tweeters if engineered properly can sound much better than dome tweeter systems not engineered properly. In fact they can be right up there with properly designed dome systems. The reason for avoiding these things is not that they cannot be done properly it is that they are rarely done properly making them both difficult things for us to recommend and leaving us disappointed with most of our past experiences with them.

Great to see all the discussion!

By: alan

alan — Thu, 01 Sep 2011 20:23:38 +0000

Comb filtering, which many audiophiles and, I suspect, plenty of “pro” installers don’t understand, is a measurement artifact, audible with pink noise but not an issue with music and programming material. In fact, our brains and hearing ignore comb filtering and, to a degree, even like it. Comb filtering occurs all the time when you’re listening in stereo or surround sound. To eliminate it, you’d need to listen in mono, preferably to a single driver.

I am basing my negative comments regarding perf screens from the “Mix” magazine tests you can read about here: http://mixonline.com/mag/audio_new_perforated_screens/. Judging by their frequency response curves, the losses are anything but “miniscule” for most of the perf screens.

So yes, I would recommend using two centers as described over typical perf screens unless you have specific confidence in the perf screen you are using. Comb filtering is a red herring and hence not an issue. Axiom has conducted numerous double-blind tests of comb filtering artifacts and the results are very conclusive. It is also covered quite extensively in “Sound Reproduction” by Dr. F.E. Toole.

* posted edited for curmudgeonlieness

By: Gort

Gort — Thu, 01 Sep 2011 18:48:36 +0000

Wow so you would recommend using two centers separated by a large physical distance over a virtually lossless perforated screen? The Comb Filtering issue of using dual centers as you suggest is far worse than any miniscule losses associated with Perforated screens. Your recommendations go against what any pro installers do and recommend. A good perforated screen losses would be on par with a loudspeaker grille cloth losses. Simply remove the grille of the speaker in favor of the screen. Of course its easier to sell (I mean recommend) two center channels as a “better” option. Try visiting a local IMAX theater and notice they don’t use multiple center channels. They use Horn loaded speakers behind perforated screens. The results are quite outstanding!

By: alan

alan — Thu, 01 Sep 2011 16:13:04 +0000

Hi Nelson,

Thanks for your comments. I doubt you’d hear any frequency response losses or aberations from a perforated screen using movies and surround-sound programming. The losses are not dramatic, however, I tend to take a purist approach, and if you listened with music, in stereo, and used a blind comparison, I’m certain you’d detect the differences.

Some of the best tests of perforated screens were conducted a few years ago by “Mix” magazine. One of the screens in those tests was excellent; the others had noticeable response anomalies which would be detectable with music playback in a controlled setting.

Hearing the dialogue from behind the screen is certainly an advantage, although the same effect can be achieved with a non-perforated screen by using two center-channel speakers, one above the screen and one below, running in mono, so the dialogue images at the screen center. We’ve been recommending this approach at Axiom for some years, and the results are excellent.

Alan at Axiom Audio

By: Nelson

Nelson — Thu, 01 Sep 2011 15:24:58 +0000

Good article. However, I must disagree with the comment about perforated screens. I recently installed my home theater with the LCR and four inwall subs behind a perforated screen from Seymour electronics. Picture and sound quality are amazing. Hearing dialogue coming from behind the screen where the actor is speaking is very addictive and no turning back once experienced.

By: Gort

Gort — Wed, 31 Aug 2011 14:53:21 +0000

Harman designs per NRC gospel so why would JBL Sythesis be “colored” as you describe horns to be? I have heard at least 2 upscale home theaters employing JBL Synthesis and the results for music and movies were anything but colored. I listen to a lot of classical music and I play the bass so I know what instruments are supposed to sound like live and unamplified. thanks.

By: alan

alan — Wed, 31 Aug 2011 13:45:55 +0000

Hello Gort,
I have heard the JBL Synthesis system and it is very good; in fact, the design was largely driven by an old friend, Dr. Floyd Toole, in his role as vice-president of engineering at Harman International, the parent company of JBL.
I wouldn’t disagree with you on the efficiency, power handling and directivity of well-designed horn systems and these traits are all required to fill large theaters, cinemas and big spaces.
However, it’s my experience that horn-loaded speakers generally have audible coloration compared to the best non-horn loaded speakers; it’s especially noticeable on strings, female vocals and other instruments. Users of horn systems become accustomed to the colorations and to their ears the horn speakers sound “natural”.

Alan at Axiom Audio

By: Gort

Gort — Tue, 30 Aug 2011 20:48:02 +0000

I disagree with the stereotype against horns. To date JBL Synthesis are the best sounding home theater speakers I’ve ever heard. They are an industry reference. Guess what, all of those speakers have horns. Horns have equal merit to any other design and if executed properly, they are usually a better option than domes as far as efficiency, power handling and directivity.