• New Patreon Tier and Early Access Content available. If you would like to support AVForums, we now have a new Patreon Tier which gives you access to selected news, reviews and articles before they are available to the public. Read more.

Dedicated Center or 1 Bookshelf Speaker?

weyland-yutani

Established Member
I keep reading reports of people ditching their dedicated center speaker(woofer-tweeter-woofer) for a standard speaker with just a woofer-tweeter. Have any of you tried this and found it improved the sound of your system?

Thanks. :smashin:
 

PSM1

Distinguished Member
My centre (PMC DBc) is just a bookshelf speaker (DB1) with the tweeter moved slightly and placed on its side. Hence I have only 1 woofer and 1 tweeter and it sounds great. There is no reason why a bookshelf speaker as a centre would not work just as well as a dedicated centre.
 

HiFiRuss71

Distinguished Member
In an ideal world the front three speakers are not only the same as the L & R speakers, but run in the same orientation at the same height too - It's the only way to achieve the ideal of identical sound across the front three.

That you need a specialized centre of differing design is a bit of a myth and it's only really the practical consideration of say, matching a centre to a pair of floorstanders, or lack of space for vertical mounting that make them a necessity in some cases.

Russell

Russell
 

weyland-yutani

Established Member
That you need a specialized centre of differing design is a bit of a myth and it's only really the practical consideration of say, matching a centre to a pair of floorstanders, or lack of space for vertical mounting that make them a necessity in some cases.

So, are center speakers over engineered and are they actually detrimental to a surround system?
 

BlueWizard

Distinguished Member
The typical Center speakers is based around a D'Appolito design. But that M-T-M design (midbass-tweeter-midbass) was intended to be used Vertically. When place horizontally, the core of the design concept simply doesn't work. One of many problem with a horizontal M-T-M design is a notch in the frequency response at the crossover frequency.

Now some designs that look like standard 2-way MTM are really 2.5-way. This means the left and right bass speakers do not cross over at the same point, which in turn means that at least one of the problems is eliminated.

The horizontal MTM design is something of a necessity. If you have a very large dedicated Home Theater room, you might be able to position everything so you can have a vertical floor mounted center speaker. But that take a very large room with very high ceilings and tiered seating. My fantasy room.

However, in the average living room, there are few real choices, either mount the center above or below the screen, but neither is really able to accommodate a vertical center speaker.

But, a good matching bookshelf can indeed do a very good job as a center. In fact the Swedish speaker maker XTZ doesn't really make any Center speakers. They simply use one of their bookshelf speakers, which can be bought as a single speaker, in place of a common Center speaker.

The horizontal MTM is something of a compromise. It is the most speaker that they can get into the least amount of space, and even with that, we get people complaining that they just don't have enough room to place their Center speaker.

We do the best we can under limiting circumstances.

That said, they are discovering ways to make improvements on the basic horizontal MTM design, and the most significant is to simply make the speaker a 2.5-way or 3-way.

Steve/bluewizard
 
Last edited:

HiFiRuss71

Distinguished Member
So, are center speakers over engineered and are they actually detrimental to a surround system?
Yes and no and yes and no.

First, one of the great myths is that because centre speakers carry a lot of the on screen action and dialogue, that they need to be some sort of uber speaker compared to the pair standing either side. All of the channels of are able to carry the same maximum levels of sound and cover the same frequency range, so the truth is that ideally, all of the speakers need to be equally capable.

Second, yes a poorly designed 'dedicated' centre can sound worse and simply by dint of being larger with extra drivers, is unlikely to sound different to the stereo pair, thus undermining the whole point somewhat. That said, a well designed unit can pull that trick off, but arranging two (or more) drivers horizontally, especially where the upper frequencies are concerned, can cause some weird effects as you start to move away from sitting dead centre. It's much the same effect as standing up to listen to your main speakers where you change the relative distance of the two drivers if not the actual distance by much. This is why you will see that all of the really good centres have a vertically arranged treble/midrange array of drivers, with only the lower, less fussy frequencies being left to a pair of bass drivers.

Again it's not gospel, but the point is just because a speaker is sold as a centre, doesn't necessarily mean it's actually any good, nor that turning an identical LCR speaker on it's side will be a total answer either. The only array that is guaranteed sound entirely consistent across the front is three identical speakers at the same height, but that equally doesn't mean there aren't some excellent centres that are carefully designed to work well in their roles.

What is a shame is that too few manufacturers make speakers available singly for you to make your own choices. The cynical might say that there's more money in a a £500 pair plus a £300 centre, than in a £750 triplet if you catch my drift.

This subject is a personal pique of mine. I ranted about it in my blog yonks ago and I haven't changed my mind much, but the one thing I forgot to include back then was the biggest myth of all - that everybody needs or will benefit from having a centre speaker.

Russell
 

Steve413

Distinguished Member
There is a fantastic article about this exact topic, which makes for very interesting reading.

visit............seymourav.com..............screens 'Think vertically'
 

Londondecca

Established Member
With my relatively low spec but good value SVS speakers, I found replacing the dedicated centre speaker with one of the rear speakers helped improve the overall coherence of the sound, as there is now 3 identical front speakers. The old centre speaker now serves as a rear speaker.

I could not suggest this approach would be best for everyone but for my speakers it worked well
 

BlueWizard

Distinguished Member
There is a fantastic article about this exact topic, which makes for very interesting reading.

visit............seymourav.com..............screens 'Think vertically'

Here are the three most telling charts from this article which can be found reprinted at Audioholics.com -

The article -

Vertical vs Horizontal Center Speaker Designs -; Reviews and News from Audioholics

The Charts -

An MTM Center speaker placed Horizontally -

$250 MTM Horizontal Center Chart

We are primarily concerned with the area marked off by the yellow line. Notice the big drop in the midrange around the crossover frequency at 2.4khz.

Here is the same speaker placed Vertically -

$250 MTM Vertical Center Chart

Notice the previous drop near the crossover has completely recovered.

Here is a similar two driver bookshelf system -

$115 Bookshelf Speaker matching the $250 Center

Notice that there are no problems with drop outs near the crossover frequency, nor any significant drop outs any where (ignoring the high frequencies).

If you open each of the graphs in its own TAB or Window, and switch between them, the difference is pretty dramatic.

Variation of ±3db are pretty much insignificant, especially if they are narrow.

I'm using links to the graphs rather than including them as images because I don't think we are allowed to us graphics we don't actually own.

The horizontal MTM Center is a flawed design, but for most people, it is a necessary one. However, if it is NOT necessary in your specific case, it should be avoided. A bookshelf matching your other front speakers would be a better choice, and a speaker literally matching your other front speakers would be the ideal choice.

Steve/bluewizard
 
Last edited:

Don Dadda

Distinguished Member
I read this thread with interest as i asked this question a few years back when i first joined and was given much the same answer but not as in depth. So thanks to Steve for providing the links- made for some good reading.

I wanted to use a an old bookshelf as a centre that i thought about repairing, but the repair costs was shockingly high, so i ditched the idea and bought the matching centre to the fronts which although good, where you sat made a difference to the soundstage that i don't care for very much.

After reading this, it had me thinking again, but the speaker i thought about using is a wharfdale 9.0 and is of different sounding to the AE Neo 3 fronts i have, so i have my doubts it will blend well. When i find the time, i will try it out as its not going to cost me anything and if it does blend well, will swap to using that.
 
Last edited:

HiFiRuss71

Distinguished Member
I can't speak for the original Neo Centre, but the current Neo Centre V2 is a 2 1/2 way design, so the lobbing issues, such as they are, are only centred around the crossover, not as a result of the distance between the mid/bass drivers, as only one covers the mid-range.

Certainly the one I have in my front room seems to be one of the better examples of the breed. It's sealed, rather than ported to avoid excessive bass
output that it could suffer by being closer to a room boundary and the not-quite-MTM alignment shows they've thought about it a bit too.

Russell
 
Last edited by a moderator:

Don Dadda

Distinguished Member
Cheers Russell

Even though the lobbing effect is not desireable, in all honesty, it's not that big of an issue to the house to the warrant upgrading to the V2. i Just thought of using what i have at my disposal to try this out.
We still enjoy our films regardless, (i can tell this by the response i get during a flim..."uh!!...uh!!") and nobody else is complaining about it so it must just me being maticulous.

All in all, i am quite happy with it as i always have the 'plum' spot (Dad's perogative :D)
 

The latest video from AVForums

Is 8K TV dead? Philips OLED+907, Pioneer LX505 AVR plus B&W 700 S3 Reviews & Visit + AV/HiFi News
Subscribe to our YouTube channel

Full fat HDMI teeshirts

Support AVForums with Patreon

Top Bottom