Anyone using multiple fronts and centers?

**Scuba Diver** · **10-27-07, 07:29 PM**

I would like to know if anyone is using 2 or more centers, fronts, and backs. Do you like the results? Does it require the need for seperate amp? Or is a quality Stereo enough to get the job done?

**Kal Rubinson** · **10-27-07, 09:35 PM**

Quote:

Scuba Diver wrote:

I would like to know if anyone is using 2 or more centers, fronts, and backs. Do you like the results? Does it require the need for seperate amp? Or is a quality Stereo enough to get the job done?

I cannot think of any good reason to do this in a domestic situation.

Kal

**Prof.** · **10-28-07, 07:22 PM**

Several HT builders at AVS have more than one centre speaker..as I have also..but not duplicate L or R or backs.

They have one centre speaker mounted above the screen and one mounted under the screen..
Angling a single centre speaker up or down can sometimes have an adverse effect..particularly with centre speakers that have rear firing drivers and or ports
Instead of directing the sound towards the centre line of the screen, the sound becomes more localized, infact not angling the speaker can sometimes work better..

Having a top and bottom centre speaker helps to offset the problem..
I have three centre speakers, one above the screen and two below...The top speaker has two rear firing bass speakers and ports, and the bottom speakers have rear firing ports..

They are wired in series/parallel to maintain impedance matching with the other speakers..

The result of this setup is that I get good strong pinpoint voice location across the entire screen, with no emphasis above or below the horizontal centre line of the screen..

**Kal Rubinson** · **10-28-07, 08:22 PM**

Quote:

Prof. wrote:

They have one centre speaker mounted above the screen and one mounted under the screen..

In compensation for other problems but not ideal.

Quote:

Angling a single centre speaker up or down can sometimes have an adverse effect..particularly with centre speakers that have rear firing drivers and or ports
Instead of directing the sound towards the centre line of the screen, the sound becomes more localized, infact not angling the speaker can sometimes work better..

Rear firing drivers are already suboptimal unless they are cutoff below 200Hz or so and angling also is compensating for sub-optimal placement.

<<<snip>>>

Quote:

The result of this setup is that I get good strong pinpoint voice location across the entire screen, with no emphasis above or below the horizontal centre line of the screen..

Again, it is in compensation for being unable to place the speaker where it should be (and I acknowledge the difficulty without an AT screen). Are all three in the same vertical axis?

Kal

**Scuba Diver** · **10-28-07, 11:33 PM**

After reading both posts it looks to me that one set of perfectly placed speakers (as long as room acoustics and space permit such a set up), should be all any in home theater should require. However, if you have a difficult lay out or lack the knowledge or proper testing equipment installing several speakers can correct poorly placed speakers allowing you to obtain the same goal. Is this correct? If so it is a matter of money. You can place speakers right or spend more money on extra speakers and place them in ok positions.

I only have the two of you to go by so I guess I will need to pull out some old speakers and try doubling up and see what kind of improvements I get. I may need more speaker wire for the test and was trying to prevent spending any money.

Thanks for the advice. I will try both of your suggestions.

**Prof.** · **10-29-07, 06:58 PM**

Quote:

Kal Rubinson wrote:

Again, it is in compensation for being unable to place the speaker where it should be (and I acknowledge the difficulty without an AT screen). Are all three in the same vertical axis?

Vitually, yes...The bottom two are side by side (upright), in the vertical centreline with the top speaker..
I originally tried it with just one at the bottom, but the top big one ( which has 7 speakers in a 3 way crossover system) is an 6 ohm unit and is more efficient than the bottom 2 way 6 ohm speaker..So I parallel wired the two bottom speakers, and series connected the top speaker, giving an approx. total overall of 9 ohms..The Receiver is set to 8 ohms..
This just about perfectly matched the efficiency of all the speakers..

I only claim that this is only practical when using centre speakers that have rear firing speakers and or ports..
If one is using a standard sealed system or a bass reflex system with front ports, then one speaker above or below the screen is all that is needed..

**Prof.** · **10-29-07, 07:11 PM**

Quote:

Scuba Diver wrote:

However, if you have a difficult lay out or lack the knowledge or proper testing equipment installing several speakers can correct poorly placed speakers allowing you to obtain the same goal. Is this correct?

It's not the placement so much, just about anyone can find a suitable centre position for their speaker, it's more the type of centre speaker as I've mentioned in the post above..

If you are using a sealed enclosure type speaker, or a BR with front ports, then one above or below the screen is all you need..
Other than that, the centre speaker should match tonally and efficiency wise with your left and right speakers..

**salvasol** · **10-29-07, 07:53 PM**

Quote:

I would like to know if anyone is using 2 or more centers, fronts, and backs. Do you like the results? Does it require the need for seperate amp? Or is a quality Stereo enough to get the job done?

Why you want two or more set of speakers????

I have two pairs of front speakers (2L + 2R)

... I got opinions that I might have problems, but I didn't listen

and set up the two pairs ....

I did it, not because I was lacking sound, the speakers sounded good to me (but, I need to use REW to know for sure how my system is performing) ...

I did it, because I removed a pair of speakers that I was using as surround, and instead of putting them away I decided to add that pair in the front .. now I'm using them with the speaker selector A + B in my receiver.

I gained 5bds using the four speakers instead of two ... but after I use REW, I will decide to keep it or remove it ...

Here is a picture of what I have (you can see that my speakers are small, that help with position)

**Prof.** · **10-29-07, 08:15 PM**

Do you get a "bigger" sound from the dual left and rights?...
This was something that I was going to try, but was advised that it's not the best idea to combine A+B speakers on the receiver..

**Kal Rubinson** · **10-29-07, 09:11 PM**

Quote:

Prof. wrote:

Vitually, yes...The bottom two are side by side (upright), in the vertical centreline with the top speaker..

Both cannot be in the vertical centerline if they are side-by-side. They will interfere with each other.

Quote:

I originally tried it with just one at the bottom, but the top big one ( which has 7 speakers in a 3 way crossover system) is an 6 ohm unit and is more efficient than the bottom 2 way 6 ohm speaker..So I parallel wired the two bottom speakers, and series connected the top speaker, giving an approx. total overall of 9 ohms..The Receiver is set to 8 ohms..
This just about perfectly matched the efficiency of all the speakers..

I only claim that this is only practical when using centre speakers that have rear firing speakers and or ports..

This is such an odd-ball setup that no lessons can be drawn from it. If it floats your boat, fine.

Kal

**Kal Rubinson** · **10-29-07, 09:13 PM**

Quote:

salvasol wrote:

Why you want two or more set of speakers????

I have two pairs of front speakers (2L + 2R)

... I got opinions that I might have problems, but I didn't listen

and set up the two pairs ....

I did it, not because I was lacking sound, the speakers sounded good to me (but, I need to use REW to know for sure how my system is performing) ...

I did it, because I removed a pair of speakers that I was using as surround, and instead of putting them away I decided to add that pair in the front .. now I'm using them with the speaker selector A + B in my receiver.

I gained 5bds using the four speakers instead of two ... but after I use REW, I will decide to keep it or remove it ...

Here is a picture of what I have (you can see that my speakers are small, that help with position)

I grew out of these machinations when I was a kid. If you use REW, try measuring a few microphone positions within several inches of each other. Bet they show widely varying results.

Kal

**jackfish** · **10-30-07, 08:19 AM**

I would stack them vertically in a WTTW configuration and see if there is an improvement, especially in the midrange. I have Large Advents so stacked and the sound is incredible.

**salvasol** · **10-30-07, 01:32 PM**

Quote:

Prof. wrote:

Do you get a "bigger" sound from the dual left and rights?...
This was something that I was going to try, but was advised that it's not the best idea to combine A+B speakers on the receiver..

Do you remember Why is not a good idea to combine A + B speakers???

I gainned 5 bds using them together (I used the SPL to measure the sound with one and the two pairs and that was the difference)

This is a temporary set up ... I have to use REW to measure the response to decide if I keep it or not.
Somethimes we like to experiment things, Right

**salvasol** · **10-30-07, 01:36 PM**

Quote:

jackfish wrote:

I would stack them vertically in a WTTW configuration and see if there is an improvement, especially in the midrange. I have Large Advents so stacked and the sound is incredible.

My problem is that the ceiling if very close (about 12") and if I stack them vertically I'm not sure if they will fit

**Otto** · **10-30-07, 02:32 PM**

Quote:

salvasol wrote:

Do you remember Why is not a good idea to combine A + B speakers???

Most likely because they will be run in parallel, thereby presenting a difficult load to your receiver/amp. Depending on the receiver/amp, this may or may not present a problem. If it's a problem, it will most likely be present at higher volumes, as that's when the most current will be demanded from the amplifier. All that said, I have done all types of parallel speaker installations and A+B installations (my own stuff, I'm not a pro "installer") over the years and have never had a problem. If you find that your receiver/amp is getting hot, distorting or shutting down, then you have a problem. If not, go for it.

Quote:

I gainned 5 bds using them together (I used the SPL to measure the sound with one and the two pairs and that was the difference)

Yeah, I would have predicted a 6 dB gain, so you're right on target. However, keep in mind that absolute SPL gain isn't the only thing we're going for.

Quote:

This is a temporary set up ... I have to use REW to measure the response to decide if I keep it or not.
Somethimes we like to experiment things, Right

I agree that it's cool to experiment. But I think I'm with Kal on this one. Even if REW measures well or the same, I think overall sound will be better with only the one pair of speakers. There's just too much going on with the combining of the speakers. But if you like it, go for it!

**Sonnie** · **10-30-07, 04:14 PM**

I wonder how it would be to stack them on top of each other with the top speaker turned upside down where both tweeters are closer together...

**Scuba Diver** · **10-30-07, 04:35 PM**

I tried it. I have 4 surrounds and 2 centers. This is not the best test setup as the 2 centers are not the same brand and are obviously not matched. One center above and one below. One set of speakers are about level with the lower center and the second set is about level with the top center. I am not intrested in numbers just sound for now.
I can honestly say it placed the center sound completely dead center of the screen. My wife thinks I am nuts. She sat down to listen I told her to close her eyes. First, I moved the single center to several positions until I found the spot she said is sounded best. Without telling her, I turned on the top center and she instantly began to smile. She said "It sounds better.... so are you trying to get my permission to spend more money"

Of course there is a good chance that the center speaker I own may not be right for this room. All I know is it sounds better to me and my wife with more than one speaker.

I will experiment more later. I would never have tried this if it wasn't for the fact that I have always been able to point out the center speaker with my eyes closed. At least until now. I honestly can not tell where the sound is coming from.

**salvasol** · **10-30-07, 05:14 PM**

Quote:

... At least until now. I honestly can not tell where the sound is coming from.

I know .... from the speaker

**Prof.** · **10-30-07, 05:33 PM**

Quote:

jackfish wrote:

I would stack them vertically in a WTTW configuration and see if there is an improvement, especially in the midrange. I have Large Advents so stacked and the sound is incredible.

That sounds like a good idea...definitely worth trying

**Prof.** · **10-30-07, 05:41 PM**

Quote:

Otto wrote:

Most likely because they will be run in parallel, thereby presenting a difficult load to your receiver/amp. Depending on the receiver/amp, this may or may not present a problem. If it's a problem, it will most likely be present at higher volumes, as that's when the most current will be demanded from the amplifier.

Yeah...That's pretty much it..
I think I was told that it reduces the dampening ability of the receiver..

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