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Macca
04-01-2015, 16:47
I've been saying it for years, turns out this bloke agrees:

http://www.cnet.com/news/attention-home-theater-shoppers-think-twice-before-buying-a-center-channel-speaker/

Okay, disappointingly it's not the Steve Guttenburg from Police Academy Two and 'theatre' is spelled 'theater' but good to see someone agrees with me. :)

If you have one sell it now before word gets round and discover what it is like to properly hear the dialogue on film soundtracks...

walpurgis
04-01-2015, 16:56
All a centre speaker does is reduce the separation between front speaker left and right signals. In other words, it's detrimental.

I hate surround sound and home theatre type system. They're unrealistic!

RMutt
04-01-2015, 17:12
I did once try to initiate discussion on the merits or otherwise of buying two for stereo use. At the time I had noticed some dealer offers and sales on the auction site where to buy two centres would have been much cheaper than buying a stereo pair. I wondered if they were voiced differently. Academic now, my home brew Magisters are fantastic, but, are there differences?

StanleyB
04-01-2015, 17:52
One of the things that customers often ask about the speaker switch box that I sell is if it can be used for switching in and out the centre speaker in an AV set up. So I think that there are quite a few people who must have come to the same conclusion that the centre speaker can be a nuisance in some/many cases.

Macca
04-01-2015, 17:59
I did once try to initiate discussion on the merits or otherwise of buying two for stereo use. At the time I had noticed some dealer offers and sales on the auction site where to buy two centres would have been much cheaper than buying a stereo pair. I wondered if they were voiced differently. Academic now, my home brew Magisters are fantastic, but, are there differences?

Depends on the design but usually you have two bass/mids and a tweeter, with the two bass/mids outputting the same signal which is unusual but not unheard of in a speaker designed for 2 channel/stereo. So probably not a great idea - there are some centres that just use 1 driver and a tweeter, that would work better for stereo.

walpurgis
04-01-2015, 18:34
Depends on the design but usually you have two bass/mids and a tweeter, with the two bass/mids outputting the same signal which is unusual but not unheard of in a speaker designed for 2 channel/stereo. So probably not a great idea - there are some centres that just use 1 driver and a tweeter, that would work better for stereo.

If it has three speakers (or more), with a centre front, then it's not stereo.

RMutt
04-01-2015, 18:44
Just had a quick look at ATC as an example. Two of their centres complete with two bass/mids each would be £900 odd. A stereo pair with similar frequency range and only one bass/mid per side would be about £1200. I presume the two bass/mids on a centre are to achieve an aesthetically symmetrical and even sound balance. Turned on their end what are the problems?

walpurgis
04-01-2015, 18:58
Just had a quick look at ATC as an example. Two of their centres complete with two bass/mids each would be £900 odd. A stereo pair with similar frequency range and only one bass/mid per side would be about £1200. I presume the two bass/mids on a centre are to achieve an aesthetically symmetrical and even sound balance. Turned on their end what are the problems?

Why would anyone want two centre speakers?

RMutt
04-01-2015, 19:02
To make a cheap(er) stereo pair.

walpurgis
04-01-2015, 19:03
To make a cheap(er) stereo pair.

It ain't gonna work.

RMutt
04-01-2015, 19:07
Yes, Macca said the same, but I want to know why. What are the technological issues?

walpurgis
04-01-2015, 19:22
Centre speakers are usually designed with rather restricted bandwidth. The cabinet volumes are smaller and main drivers can be smaller. Compare specs with main left/right speakers and you'll see what I mean.

RMutt
04-01-2015, 19:33
The ATC centre example I used actually went lower in the bass. Admittedly it only went to 20khz as opposed to the 22khz at the upper end compared to their similar dedicated stereo set. But considering you get six drivers as opposed to four, I still do not really understand the price difference. It would be nice if someone could experiment, but as you pointed out, who has two centre speakers?

Macca
04-01-2015, 20:16
Most speakers you see with 2 bass drivers have one handling the full range and the other just handling bass from around 400Hz and down i.e 2 and a half way. So the lower driver is just a passive subwoofer. But if you run both drivers with the same signal as with a centre speaker you will get some phase and cancellation issues. Someone more technical than I am can no doubt explain in detail. In any case you can do this with stereo speakers and some companies have, I recall Harman Kardon did a floorstander configured that way back in the 'Nineties. The advantages I can see would be efficiency, power handling and a simpler crossover. With the ATC speakers mentioned I am guessing the centre does not use the same drivers as the stereo speakers so that is why it is cheaper. One thing for certain using two of their centres as stereo speakers would not be the same as using their dedicated stereo speakers.

RMutt
04-01-2015, 20:29
Loads of speaker manufacturers/designs use multiples of the same driver. I do take the point that the drivers compared to their main stereo 'equivalents' may well be very different.

Macca
04-01-2015, 20:36
They may use the same driver or what looks like the same driver (one of them could be modified but not visibly) but they are rarely fed the same signal by the crossover.

RMutt
04-01-2015, 20:55
My mis-understanding then. I thought it was possible to achieve the equivalent of larger cone sizes by using multiples of smaller ones. I assumed each driver received the same signal.

windhoek
04-01-2015, 20:59
I've just returned to a surround setup and have decided on a 4.0 system to ensure good sonic cohesion across the front channels. Fwiw, I've got neighbours on three sides of my listening room, so don't want or need a sub.

I use it mostly with m/c DVD-A, SACD and Blu-ray audio discs (I'm not too fussed about films) and yet lots of people keep saying I absolutely need a centre speaker, well no thanks, my system rocks :)

Macca
04-01-2015, 21:09
My mis-understanding then. I thought it was possible to achieve the equivalent of larger cone sizes by using multiples of smaller ones. I assumed each driver received the same signal.

They do if there are multiple bass drivers - so if a speaker has 3 identical drivers and a tweeter, the driver immediately below the tweeter will be run from say 3 kHz all the way down to the bottom of its range and the two drivers below that will handle 400Hz and down, fed the same signal in parallel, and as you say, attempting to mimic a larger bass driver. Pretty much all mass-market WAF towers use that formula.

walpurgis
04-01-2015, 21:12
My mis-understanding then. I thought it was possible to achieve the equivalent of larger cone sizes by using multiples of smaller ones. I assumed each driver received the same signal.

Multiples of smaller drivers can offer cone areas to match larger drivers. but the smaller drivers will still have their higher natural resonance and have different tonal characteristics. What part of the signal is used for each driver in a passive design will depend on the crossover.

Macca
04-01-2015, 21:14
I've just returned to a surround setup and have decided on a 4.0 system to ensure good sonic cohesion across the front channels. Fwiw, I've got neighbours on three sides of my listening room, so don't want or need a sub.

I use it mostly with m/c DVD-A, SACD and Blu-ray audio discs (I'm not too fussed about films) and yet lots of people keep saying I absolutely need a centre speaker, well no thanks, my system rocks :)

I'm guessing you use identical speakers on all four corners?

RMutt
04-01-2015, 21:17
So if you use a tweeter and two mid/bass drivers fed the same signal, do you lose the multiple driver effect?

walpurgis
04-01-2015, 21:22
So if you use a tweeter and two mid/bass drivers fed the same signal, do you lose the multiple driver effect?

If by that you mean without crossover. The main drivers will sound different to the tweeters and the tweeters will die as soon as an appreciable signal goes through them. Large amplitude low range signals are a No No with tweeters. The crossover helps protect the tweeters (and mids if fitted).

RMutt
04-01-2015, 21:28
No, sorry, I did mean with a crossover . But with the same signal from the crossover feeding two bass/mids as opposed to one of the same.

Macca
04-01-2015, 21:28
If you run both the mid bass units all the way down you will get a different sound because you have two drivers outputting the same mid band signal whereas if you run them as described above i.e a 2 and a half way design only one driver will output midband signal. So having two drivers doing midband will change the whole presentation of the sound. Imaging in particular will be very different due to the change in the radiating pattern of the sound.

Macca
04-01-2015, 21:30
That is also why a centre speaker usually has two mids and lies on its side - so you get a wide dispersion of the sound it produces and folk sat outside the sweet spot can hear it better.

windhoek
04-01-2015, 21:39
I'm guessing you use identical speakers on all four corners?

Yes, ATC 7s front and rear although front audio is routed via my stereo amp's AV Bypass to make sure m/c music is more musical. It's not an expensive set up by a means, but I like it :)

RMutt
04-01-2015, 21:41
But turned on their end, you just have a high frequency sound coming from between the lower frequency ones. I am not sure your ears would know quite where they would be coming from and so stereo integrity should be maintained, .

Macca
04-01-2015, 21:53
But turned on their end, you just have a high frequency sound coming from between the lower frequency ones. I am not sure your ears would know quite where they would be coming from and so stereo integrity should be maintained, .

Yes you'll still get a stereo image but it will be a bit diffuse compared to using just one driver to handle the mid-bass. As I said above there are advantages to doing it and there are also disadvantages. That's speaker design in a nutshell really. If you are really into stereo imaging and sound-staging and want every instrument solid and in its place (as much as the mix will allow) then it is probably not a good idea.

RMutt
04-01-2015, 22:09
I always question established thought. Obviously not being a scientist I sometimes come up up a bit short on some subjects but my method is now ingrained and has on occasion been successful. Thank you for your patience Macca and Walpurgis.

Rush2112
21-01-2015, 18:56
Well !! Although I agree matching two different speakers, a centre and stereo pair is not the easiest task it is possible even from different brands and Denzel Washington doesn't have to sound like he's in a box !

Jac Hawk
09-11-2015, 23:27
i know i'm coming to this party a bit late, but i regularly listen to my a/v setup with stereo music re jigged and pumped out over a 5.1 setup using some of the clever jigery pokery in the amp, this makes my listening room sound much bigger than it actually is, the rears add the echo that you would expect from a larger room, the centre does what i believe a centre speaker should do and simply add a little bit of focus to what would be an extended stereo soundstage. And before any one harps up I KNOW MY SETUP ISN'T STEREO but who said listening to music had to be done in stereo, i thought the idea was to recreate a lifelike representation, 5.1 does that and more, i wouldn't blame your centre speaker, i'd blame the decoder, i.e. choose one that works best with the medium your using, if i'm watching a movie i have the amp set up completely differently to when i'm listening to music.

struth
09-11-2015, 23:36
I used to have a 5.1 system and very good it was. I then got a Yamaha soundbar thingy and felt what I lost in some respects I gained in focus. You can even add a sub if you feel the need. Dont use it now but I did find it very enjoyable listed and would have no qualms about going back to a system again... amp was a kenwood.

m10
10-11-2015, 14:22
I like the idea of the 4.0 setup for music - you might call it quadrophonic - where perhaps two pairs of mini-monitors that disappear in stereo could all but vanish into a 3D holographic soundstage. Nice. You need a powerful surround processor though, with a well specified chip (lots of MIPS) as you've got do some serious computing to put the six discrete channels of a 5.1 recording into four speakers. (This has been my experience with my subwoofer-less 5.0 system.)

Matching your centre channel as closely as possible to the main left-right pair is essential. The same brand helps, the same range is better, an identical third speaker is perfect. I have had my speakers now for 15 years, and have not been tempted to look elsewhere.

http://www.timefordvd.com/images/hardware/BW_CDM_CNT_angle2_large.jpg

For me this (or something like it) is the perfect layout for a centre speaker. Tall, bulky and heavy when it was sat on top of my Sony Trinitron, it is perfect now in the days of plasmas and projection screens where it has its own dedicated stand .