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Centre channel, Axiom and Jim Smith
#404222 05/14/14 11:01 PM
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I have heard from multiple sources that the book 'Getting Better Sound' by Jim Smith is the holy grail of speaker & equipment setup.

So as I read through his book there are multiple items that do make some sense but other parts that fly in the face of what was told to be right.

On tip #20 through #23 he touts that all your speakers especially the front 3 must be the exact same as that is the only way to make them all sound the same.

His take is that any change to the shape and components in one speaker to another would change the characteristics of how sound radiates from that speaker and so what you hear will be different than what was intended on the recording. (OK maybe)

On his tip #26, he tells that you should just say no to horizontal centre channel speakers. So even having the exact same speaker but putting it on it's side, the sound dispersement will change, so it's more directed along the horizontal axis and more wide in the vertical.. where as a vertical speaker orientation like you would have with your left and right will be the opposite.

He then goes on to say if you abosolutely need to have a horizontal speaker then you need one with the tweeter directly over top of the mid range.

The VP160 would fit that bill.

But I am wondering if he is talking in generalization of misinformation and making broad assumption that all speakers are made the same.

So for instance, will the tonal quality and sound dispersement of a VP180 be vastly different than that given off by a M80 speaker? Or have Axiom taken those issues into the design to make the off axis dispersement on the horizontal speaker match that of the vertical main counterpart?

To put Jim Smith's optinions into perspective, his tip #24 is not to have any centre channel speaker at all as he feels it is not needed and a better set of left and right speakers can generate a wide and detailed enough sound stage with out it.

I have not tried out every speaker combination to prove or discredit his posting. But I also know that people like Alan Loft don't just pull the company line because a dedicated center channel is cool. He goes with what actually works and is proven


Anthem: AVM60, Fosi DAC-Q5
Axiom: ADA1500, LFR1100 Actiive, QS8, EP500, M3, M3comp, M5
Re: Centre channel, Axiom and Jim Smith
MMM #404223 05/14/14 11:12 PM
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One word.
MARKETING


DOG is GOD spelled backwards.
What others think of me is none of my business.
M80 V3 MY GLOSS Cherry
Re: Centre channel, Axiom and Jim Smith
MMM #404224 05/14/14 11:15 PM
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Not "vastly" different. I know that Ian designs around this concept, and IMO is very successful. But you can't get EXACTLY the same dispersion out of an enclosure of such dramatically different proportions.

A phantom center channel only "works" if you don't care about people outside the sweet spot.


bibere usque ad hilaritatem
Re: Centre channel, Axiom and Jim Smith
tomtuttle #404227 05/15/14 12:30 AM
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That's the good thing about the LFRs, it sounds like the surrounds are on in direct mode.

Re: Centre channel, Axiom and Jim Smith
MMM #404230 05/15/14 02:46 AM
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Matt, I'd be in general agreement with most of those views as you describe them. On the separate center speaker point there are two advantages: the volume of the center channel can be increased independently of the mains to compensate for the low dialog level mixed into some movies; the center channel image stays anchored to the middle of the screen for off-axis listening, while the "phantom" center image shifts to the outside to stay in front of him as the listener moves to the outside(but not farther out than the speaker on that side).


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Enjoy the music, not the equipment.


Re: Centre channel, Axiom and Jim Smith
MMM #404238 05/15/14 11:13 AM
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This phenomena is definitely known by Axiom as in their blog about speaker placement of bookshelf speakers there is a section talking about putting the bookshelf speaker on it's side

Quote:
If you put the speaker on its side, that now becomes the vertical dispersion of the speaker and forces what was the vertical to become the horizontal. What does that mean? You won’t get as smooth a response off-axis.)


But what they don't go into in the video is if that knowledge was used in the design of the centre channel speakers and they are constructed in such a way to overcome that phenomenon.

If I am paying over $1000 for a centre speaker to match my M80, I would like it to sound right, and not off-axis different.


Anthem: AVM60, Fosi DAC-Q5
Axiom: ADA1500, LFR1100 Actiive, QS8, EP500, M3, M3comp, M5
Re: Centre channel, Axiom and Jim Smith
MMM #404240 05/15/14 12:49 PM
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Hello Matt,

A couple of points need special emphasis here. As JohnK has pointed out, advice about not using a center channel to anchor dialog at the screen is really limiting: you can't adjust the dialogue volume levels for lots of movies that are mixed with too-low dialog levels, or to compensate for hearing losses with age. All men over 50 suffer such losses to a greater or lesser degree, and the losses increase with age for most men.

Also, no two identical speakers will sound exactly alike using an ultra-critical test signal such as pink noise, because of the speakers' locational differences and boundary effects within the room. Try it if you want to confirm this: use pink noise and switch from the left speaker to the right speaker of an identical pair. You may be surprised at the tonal coloration that room effects cause in two identical speakers. The result is that using a third M80 as a center channel will not result in all three speakers sounding precisely the same when you do comparisons with pink noise (the latter has equal energy per octave across the audible spectrum).

However, such small differences in tonality that are audible with pink noise are not significant with program material -- dialog or music. Our brain and hearing system accommodate small differences in coloration, and blend the three front speakers into a cohesive front soundstage.

I did double-blind listening tests to the prototype Axiom VP180 and an M80 floorstanding tower. The VP180 is extremely similar to the M80, but not identical, however, it's a wonderful center channel that blends very smoothly with the M80 floorstanders.

I suspect that Mr. Smith may have not done careful listening tests using pink noise to three identical front speakers, otherwise he wouldn't make such statements. The slight differences in coloration from room effects and design configuration of the center speaker are simply not significant when playing back dialog or music.

You'll find the VP180 center speaker will be quite transparent and a beautiful match to the M80 towers.

Lastly, I do not work for Axiom anymore. I'm retired, and any contributions I make to the forums are purely to add what I've learned from decades of professional experience and because Axiom does indeed make highly neutral very good speakers at remarkably low prices.

Regards,
Alan Lofft


Alan Lofft,
Axiom Resident Expert (Retired)
Re: Centre channel, Axiom and Jim Smith
MMM #404242 05/15/14 03:14 PM
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Alan - Excellent response, as always.

Warmest congratulations on your retirement!


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Re: Centre channel, Axiom and Jim Smith
MMM #404244 05/15/14 04:30 PM
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The fact is, what he is saying in his assessment is nothing new. The actual THX parameters that they touted for years said the same thing. Also, for many years, the gurus at "Widescreen Review" emphasized this idea back in the day especially during the introduction of 5.1 DD and DTS soundtracks in the early nineties and carried the idea even further. I believe Andrew would probably remember the large flagship Mirage bipolar speakers that Widescreen Review had set up in their review listening room, these speakers were positioned in ALL the channels, not just L/C/R.

Of course, much of this is impractical, including many of Smith's ideas because of space and that is why horizontal centres were developed. Certainly they are a compromise but once you integrate a large full range centre channel in to your set-up(VP160, 180)they negate a lot of the issues he seems to be concerned about. As we all know, even if they are exactly the same model, just moving speakers in to different positions will change their tonality, the acoustics of the room will ultimately be the arbiter of that.

Unless we are dealing in virtual reality, if one has an HT room set-up and you have a movie night where several people are over to watch a movie, apologies to Jim Smith, but, it just not possible to have everyone sitting in the "sweet spot" at the same time. Full fledged professional movie theatres can't even do that.

Re: Centre channel, Axiom and Jim Smith
MMM #404245 05/15/14 04:31 PM
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My unscientific experimenting with 3 different horizontal WTW or MTM CC speakers (including the VP100) revealed virtually no detrimental audible artifacts until beyond 30 Degrees off axis. Even then the high end drop off was minimal & not a factor in our HT room. I suspect that this would be true in most real world situations. Some of this stuff is a bit overblown IMO.

The reason that I went to the bigger VP160 (with M22s L & R) was because I've been reading all over the net that the movie soundtrack mixes now direct much more content to the CC other than just dialogue. Bigger CC Speakers such as the VP160/180 are much more capable of handling this extended content.

The main problem with large CC Speakers is finding an appropriate place to put them. Many stands just can't handle them....

TAM

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