[Mike in Virginia]

I think I've read a discussion on this topic here sometime, but I can't seem to find it. I'm thinking of using two small 2-way bookshelf speakers as a center channel. The reason for two rather than one is that if I have them on their sides, mirror imaged, I'll get the symmetrical dispersion one should get from a center. I realize that I'm not going to get the timbre matching one should have in a proper front/center/front configuration, but my questions are first, does this make sense at all (aside from timbre matching considerations), and second, if it does, what would be the best way to wire it up? Two separate cable runs from the amplifier or one run with direct interconnection of the second speaker to the first (or any other way)? The speakers are 8 ohms, and the amp can handle 4 ohms on each channel.


Many thanks in advance for any ideas on this half-baked scheme.

 

[cme]

Here are a couple threads on this topic:

http://www.avsforum.com/avs-vb/showthread.php?t=531049
http://www.avsforum.com/avs-vb/showthread.php?t=525180


The latter one has links to many more. In short, center speakers with two midrange drivers in a horizontal array are a compromise, not ideal. Most recommend a single speaker for the center channel.


If you already have two speakers to play with, a vertical array is preferable since any comb filtering is vertical and the listener usually sits at a fixed height. If you want to play with two center speakers, try one above the other, as opposed to two next to each other.

 

[cme]

If you don't have seperate amplifiers, here is an article on serial & parallel wiring schemes that provide the same impedance:

http://www.termpro.com/articles/spkrz.html

 

[Wayne A. Pflughaupt]

Quote:

The reason for two rather than one is that if I have them on their sides, mirror imaged, I'll get the symmetrical dispersion one should get from a center.

Great idea, but flawed reasoning. The fifth post in the second link cme posted does a great job of explaining why: Anytime you have two sources playing an identical signal, especially if they’re right next to each other like you’re proposing, you’ll get comb filtering in most seat locations. The reason is that there will be a slight time delay between the two.


I’ve been using a regular bookshelf speaker for my center channel for years – works great. So use just the one speaker and put the other one in the closet.


Yes, I know - some people just can’t do that without feeling like “I’m wasting a speaker,†which is silly. After all, you don’t use every input on your receiver, to you? Or feel cheated if you don’t drive your car at top speed all the time.


Regards,

Wayne A. Pflughaupt

 

[Mike in Virginia]

Many thanks to all. I hadn't understood the comb filtering issue at all, so I suspect I'll try one and see if that's satisfactory before I try something fancier (or buy a new one).


Mike

 

[cme]

If you read through those threads, you probably already saw the advice to get a center speaker identical to your mains (if it fits with your particular setup).


If you are running a projector, there are some threads that I just stumbled across (years late, I know) about relatively acoustically transparent, inexpensive ($100), DIY screens.

 

[Mike in Virginia]

Actually I've already gotten that advice, but I'm using a 25-year-old pair of Allison Ones as my mains, and I really want to keep them for that purpose. (Another issue is the resurrected Allison company and their almost having survived long enough to sell me their new Center Channel, but that's another thread entirely.)

 

[Samurai Jack]

I was curious about this for another purpose...running two sets of side-surrounds...one for each row. Anyone doing this? Comb filtering a problem? Seperate amp required?

 

[Wayne A. Pflughaupt]

Quote:

I'm using a 25-year-old pair of Allison Ones as my mains, and I really want to keep them for that purpose.

Did Allison make any small bookshelf speakers similar to the Ones? If so you might look for a couple pairs on eBay, and use them for your center and surounds. You’d have a reasonably-timbre matched system then. The only caveat would be that they’re most likely not shielded, so you’d have to be careful about placement near the TV.

Quote:

I was curious about this for another purpose...running two sets of side-surrounds...one for each row. Anyone doing this? Comb filtering a problem? Seperate amp required?

Yes, it would be best to use a second amp.


Comb filtering would be there but less of an issue, because things like that aren’t readily noticeable with the surrounds (remember, Dolby Surround and Pro-Logic used a mono rear channel shared by two speakers), and because the people will primarily hear the closest speaker.


Regards,

Wayne A. Pflughaupt