Dual Center Speakers

[AcuDefTechGuy]

Okay, I have 2 identical CLR3000 center speakers. The four 6.5" midrange drivers are about 13" apart from each other vertically and horizontally.

View attachment 5702

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I've listened to 5.1 SACDs & 5.1 DVD-Audios, & watched 5.1 movies.

At first, they sounded great. It sounded like before, except the sound seemed clearer. Then I realized that the Center Channel Volume Level was about +8dB above the other channels when I did the calibration with my Galaxy SPL meter. I guess the two center speakers added to the volume. So I turned the center channel preamp volume down to match the other channels.

Then, it sounded just LIKE before.

At times, I thought the 2 CLR3000s were speaking to each other.
Like when 2 characters were talking back and forth on screen, I thought the 2 center speakers were talking back and forth to each other.

But then I realized that it was just the imaging between the Front Left, Center, and Front Right speakers.

So I guess using dual center speakers is kind of like bi-amping. Sure, they look cool, but that's probably about it.

It makes me wonder why that guy used 3 center speakers in his 6 million dollar system? Because they looked cool?

 

[ParadigmDawg]

You get a little more crazy everyday, please seek help...

 

[GlocksRock]

I'm not sure why that guy had so many center channels, probably because he needed them to make a full circle of equipment, but it does seem like overkill to have more than one center channel for any normal sized HT setup. I suggest you return the second CLR 3000 and put that money towards the BD50 when it comes out.

 

[TLS Guy]

Okay, I have 2 identical CLR3000 center speakers. The four 6.5" midrange drivers are about 13" apart from each other vertically and horizontally.

View attachment 5702

View attachment 5703

I've listened to 5.1 SACDs & 5.1 DVD-Audios, & watched 5.1 movies.

At first, they sounded great. It sounded like before, except the sound seemed clearer. Then I realized that the Center Channel Volume Level was about +8dB above the other channels when I did the calibration with my Galaxy SPL meter. I guess the two center speakers added to the volume. So I turned the center channel preamp volume down to match the other channels.

Then, it sounded just LIKE before.

At times, I thought the 2 CLR3000s were speaking to each other.
Like when 2 characters were talking back and forth on screen, I thought the 2 center speakers were talking back and forth to each other.

But then I realized that it was just the imaging between the Front Left, Center, and Front Right speakers.

So I guess using dual center speakers is kind of like bi-amping. Sure, they look cool, but that's probably about it.

It makes me wonder why that guy used 3 center speakers in his 6 million dollar system? Because they looked cool?

It's worse, there will be comb filtering between speakers. At some frequencies there will be addition and at others cancellation. Overall the level should be up around 6db over a single speaker.

 

[AcuDefTechGuy]

It's worse, there will be comb filtering between speakers. At some frequencies there will be addition and at others cancellation. Overall the level should be up around 6db over a single speaker.

So would having 3 center speakers make it even worse than 2 center speakers?

And having multiple speakers for each channel also make it worse (like having 2 front Lefts, 2 front rights, etc.)?

About the comb filtering, would having the speakers spaced close together help or make the comb filtering worse?

 

[Midcow2]

Why not upgrade to one better quality center speaker ?

It's worse, there will be comb filtering between speakers. At some frequencies there will be addition and at others cancellation. Overall the level should be up around 6db over a single speaker.

Actually two speakers over one single speaker would be exactly +3dB because there is no synergistic effect.

It is analogous to going from 100w to 200w = +3dB

Instead of adding a second center speaker, why not upgrade the center speaker quality with a "BigFoot" Rocket RSC200 Signature Center Loudspeaker or even better the Paradigm CC-690

 

[ParadigmDawg]

You wouldnt want to change to a different speaker company and lose the timbre matching.

Actually two speakers over one single speaker would be exactly +3dB because there is no synergistic effect.

It is analogous to going from 100w to 200w = +3dB

Instead of adding a second center speaker, why not upgrade the center speaker quality with a "BigFoot" Rocket RSC200 Signature Center Loudspeaker or even better the Paradigm CC-690

 

[TLS Guy]

Actually two speakers over one single speaker would be exactly +3dB because there is no synergistic effect.

It is analogous to going from 100w to 200w = +3dB

Instead of adding a second center speaker, why not upgrade the center speaker quality with a "BigFoot" Rocket RSC200 Signature Center Loudspeaker or even better the Paradigm CC-690

Actually those speakers being very close together playing identical program will have a gain of about 6db over single speaker. You are correct about the amp though.

 

[zhimbo]

kind of like bi-amping. Sure, they look cool, but that's probably about it.

As I understand it, the best use for dual centers is if you have a large projection screen, and you place one above and below to get a truly centered image.

AFAIK, vertical localization is pretty broad, anyway, so I don't know how often this is an important issue.

 

[TLS Guy]

So would having 3 center speakers make it even worse than 2 center speakers?

And having multiple speakers for each channel also make it worse (like having 2 front Lefts, 2 front rights, etc.)?

About the comb filtering, would having the speakers spaced close together help or make the comb filtering worse?

Yes, three would be worse. Putting them closer together would change the frequencies of sum and difference. At frequencies were the driver spacing allows wavelengths to sum there will be addition. Where they subtract a relative null.

Actually, I have found that for all but the largest HT rooms the center speaker is too close to the left and rights, usually less than 8 ft. So there is a problem here to. I have favored a coaxial driver for the center channel to minimize interference.

Speech clarity of center channels is also an issue. Unfortunately the crossover range of most speakers is right in the speech discrimination band. Very, very few crossovers have perfect phase and time response at crossover. There are practically no speakers I know of that can reproduce a square wave because of the disconnect at crossover. I think for music this problem in most designs is masked. However in speech, I don't think it is. I have noted in threads previously members have increased center channel levels to hear movie dialog. I certainly have issues with speech clarity in the majority of dealer demos I have heard unless the speaker are horribly shouty and forward.

I think the development of better full range loudspeakers for this application would be of benefit. In my coaxial system the time delay is well handled, but there are some residual phase issues. However speech clarity is good.

In my downstairs system, I made sure there were no crossovers in the speech discrimination band. Even though it is two channel, now 2.1, speech clarity is excellent. I note that B &W on their more expensive offerings, have kept the crossover out of the speech discrimination band.

I think we need a lot more research into the center channel, and its interaction with with the front mains. We also need to look into speech discrimination issues, without the too often resort to upper midrange lift, which makes for a shouty speaker, which is not natural for speech or music.

The center channel speaker should not be a weak brother of the mains, as is usually the case. It is not helped by the current horizontal MTM arrangement being the norm. To me, it is jarring, and when listeners hear a better alternative it is quite revealing.

 

[Pyrrho]

As has already been said, with two speakers, you are likely to get some cancellation, and some overemphasis, of some frequencies. You also lose the "firm" localization of where the sound is coming from, which is one of the main reasons to have a center speaker in the first place. I recommend using one center channel speaker, in all cases. With someone with a very large front projector screen, I recommend doing what is done at movie theaters: use an acoustically transparent screen, and put the speaker behind the screen. That is where the sound is supposed to be coming from. And, ideally, the center speaker will be exactly the same as the front right and left speakers, though, of course, for some people, this is difficult to do, so using a "matched" center speaker becomes a reasonable option. (Incidentally, at good movie theaters, they use identical speakers for all three front channels.)

 

[AcuDefTechGuy]

I just briefly read through this article from Audioholics:

http://www.audioholics.com/education/loudspeaker-basics/vertical-vs-horizontal-speaker-designs

I guess the take home message is that having multiple VERTICAL midrange drivers are GOOD, but multiple HORIZONTAL midrange drivers are BAD - even when the drivers are in the same speaker (single center speaker).

So just make sure you place your speakers vertically.

This makes me wonder about the super expensive ($40,000 each) Legacy Helix speaker, which has 4 midrange drivers:

http://legacyaudio.com/index.php?option=com_content&task=view&id=65&Itemid=195

I guess I got my idea of using 4 midrange drivers from this Legacy speaker.

I bet the comb filter is significant here?

I wonder what would happen if I place the 2 speakers one on top of the other to form a Vertical array of drivers, instead of horizontal?

 

[TLS Guy]

I just briefly read through this article from Audioholics:

http://www.audioholics.com/education/loudspeaker-basics/vertical-vs-horizontal-speaker-designs

I guess the take home message is that having multiple VERTICAL midrange drivers are GOOD, but multiple HORIZONTAL midrange drivers are BAD - even when the drivers are in the same speaker (single center speaker).

So just make sure you place your speakers vertically.

This makes me wonder about the super expensive ($40,000 each) Legacy Helix speaker, which has 4 midrange drivers:

http://legacyaudio.com/index.php?option=com_content&task=view&id=65&Itemid=195

I guess I got my idea of using 4 midrange drivers from this Legacy speaker.

I bet the comb filter is significant here?

I wonder what would happen if I place the 2 speakers one on top of the other to form a Vertical array of drivers, instead of horizontal?

That would depend on the lobing pattern induced by the crossover and driver spacing. Impossible to predict. But that article you posted backs up what I was saying.

The problem with a vertical MTM arrangement is that it gets the speaker listening axis a long way from the screen. In practice I have found my coaxial arrangement with the driver right above the screen angled to the listening position has worked well. My biggest worry was getting integration with the mains, but that worked out very well also. I have long been encouraging people to try that SEAS driver and use the Loki kit. If your speakers are neutral it will blend well. If they have significant character or timbre issues may be not so well.

If any one wants to build my TL center they are welcome, and I will get the plans and cutting drawings copied.

 

[AcuDefTechGuy]

You guys were right...

I took your advice and went back to a single center speaker. It is true that a single center speaker sounds much better than two. What was I thinking?

 

[GlocksRock]

I guess you can just use that extra CLR 3000 and start building a surround sound setup for your bedroom That's what I'm doing with all my extra speakers from my upgrades.

 

[AcuDefTechGuy]

I guess you can just use that extra CLR 3000 and start building a surround sound setup for your bedroom That's what I'm doing with all my extra speakers from my upgrades.

You just had to put that idea into my head, didn't you?

Now I'm going to be thinking about all day!

Or buy another CLR3000 and go back to 7.1?

I can't believe you did that!

 

[GlocksRock]

Yeah, I got a pair of like new BP7001SC on ebay for $2150 shipped. The guy bought them last year, and only used them for about 3 months, and he said he boxed them up while he was in Iraq, so they are pristine. I didn't want to spend that much right now, but that was too good of a deal to pass up. And I just picked up some BP2X locally from an auction I won on ebay. So now I have for my bedroom system BP8, CLR 2002, and BP1.2X... I'll probably just end up getting a parts express Dayton 12" sub and I'll have to decide on a receiver, I'm looking at the low end Pioneer Elite or possibly another Yamaha... but that won't be for a while.

 

[AcuDefTechGuy]

You are just as CRAZY as I am!

Yeah, I got a pair of like new BP7001SC on ebay for $2150 shipped. The guy bought them last year, and only used them for about 3 months, and he said he boxed them up while he was in Iraq, so they are pristine. I didn't want to spend that much right now, but that was too good of a deal to pass up. And I just picked up some BP2X locally from an auction I won on ebay. So now I have for my bedroom system BP8, CLR 2002, and BP1.2X... I'll probably just end up getting a parts express Dayton 12" sub and I'll have to decide on a receiver, I'm looking at the low end Pioneer Elite or possibly another Yamaha... but that won't be for a while.

Okay, I think you won the contest for having the most Def Tech speakers in the house!

But seriously, CONGRATULATIONS!!!

Man, you will be so happy with the BP7001SCs + CLR3000 + BP10s + BP2Xs!!!

You are so up there with the big dawgs now!

And as Greg would put it, there is something seriously wrong with the both of us!!!

And did you say "for a while" on the receiver?

Yeah, right!

That means next month!

No, make that next week!

CRAZZZZZZZZZZZZZZZZZZZZZZZZZZZY!!!

You are a HARDCORE audioholic!

 

[Pyrrho]

I took your advice and went back to a single center speaker. It is true that a single center speaker sounds much better than two. What was I thinking?

There is absolutely nothing wrong with experimenting, especially if you already happen to have all you need to do the experiment. Such experimenting allows one to test things for oneself, and it is good to learn that way. Of course, even if it is "proper" to use one, if someone personally preferred to use two, they may do what they want with their own system.

 

[GlocksRock]

I already wen't out of my budget getting the BP7001SC towers, and I told my lady friend I want a sub for my birthday... so hopefully with the $600 I'll be getting back from the gov. in a few months, I'll be able to buy the receiver. Then I'll be saving up for a new tv for the bedroom... right now I'm just using some old 19" sanyo crt tv. This hobby is just waaaay too addicting.

I see in your sig you only have one amp... did you sell off the other one?