Center channel Impedance.

[StevenSurprenant]

Normally a surround system uses a single speaker for the center channel, but I have always considered that the main flaw in the design. In most home setups, the sound comes from above or below the screen and I find that very distracting. Most people get used to it and the brain compensates by creating a virtual audio image across the screen. In my case, that has never happened. My solution was to use a Yamaha receiver that has an ambience channel. This is comprised of 2 extra speakers that enhance the sound by creating extra ambiance, but also has the ability to add center channel information to those 2 speakers. When placed correctly, these extra speakers will bring the center channel information up to the center of the screen. It works very well.

I have Magnepan wall speakers and I was reading about using their center channel speakers with two additional wall speakers flanking both sides of the screen to get the same effect that I mentioned above. All their speakers are 5 ohm. The way they set it up was to wire the 2 wall speakers in series (10 ohms) and then wire the center speaker in parallel with those two for a combined impedance of 3.3 ohms. My receiver is rated at 6/8 ohms, but the specs also shows a peak output at 2 ohms. In addition, I understand that the Magnepans impedance is lowest below 200 Hz. I set the speakers to small and the crossover to 200 Hz to reduce the current to these speakers. Also, because there are now three speakers, the volume was reduced accordingly to match the main speakers. Still, I can't get it out of my mind that at times the current draw is going to be excessive and shorten the life of the receiver.

I then wired all 3 of the speakers in series for a total of 15 ohms impedance. I actually liked this way better because now all 3 speakers are at the same volume, whereas before in the previous setup, the 2 wall hanging speakers were not as loud as the center channel speaker. I realize that I have to increase the preamp section of the center channel higher than the main speakers which in turn makes that channel the limiting factor of the maximum output of the entire system (at least I assume so). I have yet to run out of power so I don't believe this to be an issue. I believe this solves the problem with too high a current drain compared to the previous configuration.

This brings me to my question...

Is it okay to run speakers at 15 ohms and is there anything else that I need to be concerned about? Is my logic correct?

You might be asking, if the ambiance speakers worked so well, why would I want to do this? The answer... The ambiance speakers only do their magic when they are engaged. If I wanted to run without them and just with Dolby or DTS, they do not function. Also I cannot run 7.1 surround and the ambiance channels at the same time. Besides, I already had an extra pair of Magnepan speakers stored away that I wasn't using.

[Sir Terrence the Terrible]

Normally a surround system uses a single speaker for the center channel, but I have always considered that the main flaw in the design. In most home setups, the sound comes from above or below the screen and I find that very distracting. Most people get used to it and the brain compensates by creating a virtual audio image across the screen. In my case, that has never happened. My solution was to use a Yamaha receiver that has an ambience channel. This is comprised of 2 extra speakers that enhance the sound by creating extra ambiance, but also has the ability to add center channel information to those 2 speakers. When placed correctly, these extra speakers will bring the center channel information up to the center of the screen. It works very well.

I have Magnepan wall speakers and I was reading about using their center channel speakers with two additional wall speakers flanking both sides of the screen to get the same effect that I mentioned above. All their speakers are 5 ohm. The way they set it up was to wire the 2 wall speakers in series (10 ohms) and then wire the center speaker in parallel with those two for a combined impedance of 3.3 ohms. My receiver is rated at 6/8 ohms, but the specs also shows a peak output at 2 ohms. In addition, I understand that the Magnepans impedance is lowest below 200 Hz. I set the speakers to small and the crossover to 200 Hz to reduce the current to these speakers. Also, because there are now three speakers, the volume was reduced accordingly to match the main speakers. Still, I can't get it out of my mind that at times the current draw is going to be excessive and shorten the life of the receiver.

I then wired all 3 of the speakers in series for a total of 15 ohms impedance. I actually liked this way better because now all 3 speakers are at the same volume, whereas before in the previous setup, the 2 wall hanging speakers were not as loud as the center channel speaker. I realize that I have to increase the preamp section of the center channel higher than the main speakers which in turn makes that channel the limiting factor of the maximum output of the entire system (at least I assume so). I have yet to run out of power so I don't believe this to be an issue. I believe this solves the problem with too high a current drain compared to the previous configuration.

This brings me to my question...

Is it okay to run speakers at 15 ohms and is there anything else that I need to be concerned about? Is my logic correct?

You might be asking, if the ambiance speakers worked so well, why would I want to do this? The answer... The ambiance speakers only do their magic when they are engaged. If I wanted to run without them and just with Dolby or DTS, they do not function. Also I cannot run 7.1 surround and the ambiance channels at the same time. Besides, I already had an extra pair of Magnepan speakers stored away that I wasn't using.

This is such a bad idea, I don't know where to start. Are you calibrating your center channel with a SPL meter or calibrating software? A properly calibrated system does not need two center speakers. Two speakers reproducing the same signals introduces dispersion pattern interference that is not very good for dialog clarity.

There is a reason movie theaters and home theaters only have one speaker reproducing the center channel information.

Your claim about the sound of the center speaker being over or under the screen is simply not correct at any level. The ear/brain mechanism does a great job of putting the dialog where your eyes are, as the offset is not far enough to create a discontinuity. Even with highly directional loudspeakers, the sound is not pulled down or up from them unless you are sitting extremely close to them. At that point any picture on the screen is basically unwatchable. Your idea that a single center speaker reproducing the dialog is flawed is in itsef flawed.

The ambient channels of a Yamaha receiver cannot carry dialog. All it can carry is DSP generated and processed ambience, and that is it. If you love muddled dialog, then keep doing what you are doing, However if dialog clarity is more disireable, ditch the two center, and use one calibrated one.

[StevenSurprenant]

This is such a bad idea, I don't know where to start. Are you calibrating your center channel with a SPL meter or calibrating software? A properly calibrated system does not need two center speakers. Two speakers reproducing the same signals introduces dispersion pattern interference that is not very good for dialog clarity.

There is a reason movie theaters and home theaters only have one speaker reproducing the center channel information.

I don't mean to to contrary, but I found the opposite to be true, dialog clarity has increased, even though I know what you are saying makes sense. I suppose that there are other variables in play here. It might be that they are planer dipole speakers and not so much point sources. I don't know.

Here are links to what others have said...

Magnepan center channel field test - wendell diller - Planar Speaker Asylum

The Audio Beat - Monday at Magnepan

The Audio Beat - Magnepan's Tri-Center: The Sound of Things to Come for Home Theater?; Magnepan speakers

The Audio Beat - Magnepan's 3.7/Tri-Center System: The Second Time Around; Magnepan 3.7 and Tri-Center speakers

Tri-Center


On the other issue of "Your idea that a single center speaker reproducing the dialog is flawed is in itsef flawed." . I'm not in agreement with you except for the distance factor from the speaker. The further from the center speaker we are, the better it integrates. In most home settings, that distance isn't achievable. Oh, I also agree with you on the ear/brain mechanism, except that, for me, it takes an effort to ignore where the sound is actually coming from.

Sir... My intention is not to be argumentative. You have been a great contributor to this site and have exhibited that you have an in depth knowledge of audio. However, theory doesn't always apply, nor do our tastes always mesh. From your equipment list that you posted, your "TV" room is the exception and not the norn. Your screen is bigger than my entire wall, hence I have to assume that your room is much much larger than what I have. From that, it makes sense that your center would integrate better than what is available to me or to most people.

Just a thought...

It seems odd to me that many people compare their home systems to a theater. I quit going many years ago because of the sound (too loud). Theaters are great at producing loud sound with little distortion and the large room size is great for creating that spacious ambiance. Where theaters fall short is creating a depth to the image (it's wallpaper, if you know what I mean)..Home theaters are much better in that regard. Neither is better. all things considered.

BTW, I bet your theater systems sounds terrific.

Thanks...

Oh, one more thing...

|The ambient channels of a Yamaha receiver cannot carry dialog. All it can carry is DSP generated and processed ambience, and that is it.|

Not true, at least I don't think so. The model I have has a feature called "Dialog Lift". Granted it is a function of the ambience feature, but from what I can hear, it does just what it claims without adding additional ambience.

Normally, I am not a fan of processed sound. My 2 channel system only has a volume knob and that's it. There is no pre-amp or switching capability either. It sounds very good (to me), but I like it and the surround system equally. Needless to say, I've heard better, but at a higher cost.

[E-Stat]

There is a reason movie theaters and home theaters only have one speaker reproducing the center channel information.

And yet, I've never seen a center speaker hung below the screen at a cinema. Ever been to an IMAX where they give the sound presentation intro that includes showing the location of the speakers themselves via backlighting through the screen? Maybe not. Here are some examples:

Centers not below screen here

Nor here...

Nor here...

Nor here...

Nor here...

Even with highly directional loudspeakers, the sound is not pulled down or up from them ...

Unless of course you use tall line sources for the mains.

rw

[E-Stat]

Most people get used to it and the brain compensates by creating a virtual audio image across the screen. In my case, that has never happened.

Such is the same for me, too.

My solution was to use a Yamaha receiver that has an ambience channel. This is comprised of 2 extra speakers that enhance the sound by creating extra ambiance, but also has the ability to add center channel information to those 2 speakers.

I'm not sure that is the best approach either.

I have Magnepan wall speakers and I was reading about using their center channel speakers with two additional wall speakers flanking both sides of the screen to get the same effect that I mentioned above.

Interesting approach, but might still involve the same challenge with loss of separation.

Is it okay to run speakers at 15 ohms and is there anything else that I need to be concerned about?

Wiring different speakers in series is not ideal. Multiples of the same is fine. An amplifier won't have trouble driving the load, but the time response to the speakers will be affected. I might try using two of the identical speakers as the center with their height aligned with the mains. Just like they do at commercial cinemas.

rw

[Sir Terrence the Terrible]

And yet, I've never seen a center speaker hung below the screen at a cinema. Ever been to an IMAX where they give the sound presentation intro that includes showing the location of the speakers themselves via backlighting through the screen? Maybe not. Here are some examples:

Centers not below screen here

Nor here...

Nor here...

Nor here...

Nor here...

Unfortunately Ralph, most home theaters use televisions and not screens. All of your examples are of movie theaters, and most setups are not done that way. When you use a set(and you know this very well), you either have to put the center speaker in front of the set below it, or on top of the set. These are your only choices for this setup.

Unless of course you use tall line sources for the mains.

rw

You can't really use line sources for the center position with flat panels, but you are correct.

[E-Stat]

All of your examples are of movie theaters, and most setups are not done that way.

I merely point out that you must choose your own set of compromises in imperfect environments. While I have not heard an HT using tall line sources with a split equivalent center, my guess is that I would prefer its non-distracting image coherence to using the more common below the screen approach. I seriously doubt that Wendell Diller or either Winey would make such a suggestion without first trying it out.

rw

[Sir Terrence the Terrible]

I don't mean to to contrary, but I found the opposite to be true, dialog clarity has increased, even though I know what you are saying makes sense. I suppose that there are other variables in play here. It might be that they are planer dipole speakers and not so much point sources. I don't know.

Here are links to what others have said...

Magnepan center channel field test - wendell diller - Planar Speaker Asylum

The Audio Beat - Monday at Magnepan

The Audio Beat - Magnepan's Tri-Center: The Sound of Things to Come for Home Theater?; Magnepan speakers

The Audio Beat - Magnepan's 3.7/Tri-Center System: The Second Time Around; Magnepan 3.7 and Tri-Center speakers

Tri-Center

So let me get this straight, a guy that works for a speaker company tells you that dual or even a trio of center speakers is best. And you believe this? This guys want to sell speakers, but he must understand something called "wave interference" as demonstrated on this page.

2-Point Source Interference Patterns: Changing Separation Distance

You notice that when the speakers are separated, there is a very complex interaction between the two waves.This causes wave interference that causes cancellations and boosts to the frequency response. As the sources are moved until they almost are one source, that interference pattern decreases, and eventually would go away completely. This is what happens when dialog in split between two speakers, and why only one speaker works best for this application.

On the other issue of "Your idea that a single center speaker reproducing the dialog is flawed is in itsef flawed." . I'm not in agreement with you except for the distance factor from the speaker. The further from the center speaker we are, the better it integrates. In most home settings, that distance isn't achievable. Oh, I also agree with you on the ear/brain mechanism, except that, for me, it takes an effort to ignore where the sound is actually coming from.

This is nonsense. The fusion point is based on the size of the speakers, and the distance between the drivers. I sit 5.4" from a mini-monitor, and its drivers are long integrated with each other at that distance. It would be integrated at 2ft, and that can be easily measured using speaker measurement software like MLSSA. I can sit 10ft away from my Dunlavy SC-V, and all of the drivers sound is fully integrated at that distance. I can sit 5ft away from the system in my signature, and the drivers sound is fully fused at that distance. All of these distances are easily achievable in most hometheaters.

Sir... My intention is not to be argumentative. You have been a great contributor to this site and have exhibited that you have an in depth knowledge of audio. However, theory doesn't always apply, nor do our tastes always mesh. From your equipment list that you posted, your "TV" room is the exception and not the norn. Your screen is bigger than my entire wall, hence I have to assume that your room is much much larger than what I have. From that, it makes sense that your center would integrate better than what is available to me or to most people.

Theory does not always apply, but in this case, it does and can easily be demonstrated. Once again, look at the example above as it is a simulation of exactly what would happen when two spaced speakers are playing the same signal. You can also measure what the interference does to the overall frequency response coming from those two speakers. The effect leads to comb filtering, and comb filtering has a diffusive effect on the sound, not a cohesive effect.

This is not designed to be augmentative as well, but as a person who mixes movie soundtracks for a living, I completely understand how to get articulate dialog from a single speaker set up. You are essentially creating a phantom image between the two speakers. Phantom images have notches in the frequency response depending on how far the speakers are spread. The sound goes from a notch very close to the speakers, to full out cancellation and boosting further away. This is not good for dialog. Movie soundtracks are designed with a single discrete source for each channel across the front and sides, and matrixed or discrete channels in the back rear.



Just a thought...

It seems odd to me that many people compare their home systems to a theater. I quit going many years ago because of the sound (too loud). Theaters are great at producing loud sound with little distortion and the large room size is great for creating that spacious ambiance. Where theaters fall short is creating a depth to the image (it's wallpaper, if you know what I mean)..Home theaters are much better in that regard. Neither is better. all things considered.

Actually this is not quite correct. Movie theater sound system create depth in a DIFFERENT way than home theaters do. The sense of depth in home theater speakers comes from the complex interaction of front wall reflections at low and mid bass frequencies. Side wall reflections create a sense spaciousness. Since movie theaters are pretty reflection free at mid and high frequencies, in order to create depth, we pull images out in to the room using the surrounds. If you mirror the signals coming from the fronts to the surrounds, the image will pull into the room all the way back to the backwall with current 6.1 and 7.1 configurations.

BTW, I bet your theater systems sounds terrific.

Thanks for the compliment.

It seems from reading on the net, most folks that use this dialog left feature have their speakers far too close to the floor, or sitting on it. This is a total compromise and will induce boundary reinforcing effects to the signal. You can lift the dialog higher, but it still won't reduce the effect of the boundary reinforcement unless the center speaker is off the floor. Lift it off the floor, and closer to the television screen, and the eye/ear mechanism can do its magic.

[Sir Terrence the Terrible]

I merely point out that you must choose your own set of compromises in imperfect environments. While I have not heard an HT using tall line sources with a split equivalent center, my guess is that I would prefer its non-distracting image coherence to using the more common below the screen approach. I seriously doubt that Wendell Diller or either Winey would make such a suggestion without first trying it out.

rw

Ralph, you don't get coherence from this setup, you get destructive wave pattern interference. That is not good at all, and why you won't find many people trying this kind of set up.

[E-Stat]

Ralph, you don't get coherence from this setup, you get destructive wave pattern interference. That is not good at all, and why you won't find many people trying this kind of set up.

You continue to apply point source radiation rules to dipolar line sources. Like apples and kumquats. Once again, you must choose your choice of compromise(s). I find voices coming from below everything else distracting. Perhaps that is not the case for you. I'll repeat: there are a sum total of ZERO cinemas compromised in that way. I suspect they know what they are doing even if you don't.

In this case you are compromising an even frequency response.

Perhaps. Since there are always frequency anomalies at virtually every concert and theater, I don't find those distracting.

rw

[Sir Terrence the Terrible]

I merely point out that you must choose your own set of compromises in imperfect environments. While I have not heard an HT using tall line sources with a split equivalent center, my guess is that I would prefer its non-distracting image coherence to using the more common below the screen approach. I seriously doubt that Wendell Diller or either Winey would make such a suggestion without first trying it out.

rw

I understand your point. However some compromises just makes things worse, or creates more compromises. In this case you are compromising an even frequency response.

Remember Wendell and Winey are in the business of selling speakers, and naturally they would recommend something that....well... sells more speakers.

[Sir Terrence the Terrible]

You continue to apply point source radiation rules to planar line sources. Like apples and kumquats. Once again, you must choose your choice of compromise(s). I find voices coming from below everything else distracting. Perhaps that is not the case for you. I'll repeat: there are a sum total of ZERO cinemas compromised in that way. I suspect they know what they are doing even if you don't.

rw

The only difference between a point sources and planar line sources is in vertical directivity. It still has a very wide horizontal dispersion pattern, and that is where the problem lies. They are placing these speakers side by side, and that will create an interference pattern in the horizontal plane.

If planar line sources had both limited vertical and horizontal dispersion patterns, then you would not have a problem.

[E-Stat]

The only difference between a point sources and planar line sources is in vertical directivity. It still has a very wide horizontal dispersion pattern...

While you have a great deal of expertise in a wide range of audio topics, these statements are simply not supported by fact. The horizontal dispersion of dipolar planar line sources is anything but identical to that of point sources. Which requires different thinking and placement approaches. Having lived with them for nearly forty years, I am somewhat familiar with their characteristics.

If planar line sources had both limited vertical and horizontal dispersion patterns, then you would not have a problem.

Thank you for agreeing! Vertical dispersion is easily solved by using a tall panel. Horizontal dispersion is addressed in different ways depending upon the design. Magneplanars use mirror imaged tweeters and more toe-in to mitigate the effects. My electrostats - which most soundly (pun intended) refute your assertion about dispersion - use angled panels to address the question of horizontal beaming.

rw

[bobsticks]

How does Harry Pearson do it at Sea Cliff? I thought I'd read that he uses two Maggies horizontally for purposes of dispersion.

Why do I think I'm muddying the waters?

[E-Stat]

How does Harry Pearson do it at Sea Cliff? I thought I'd read that he uses two Maggies horizontally for purposes of dispersion.

His arrangement is quite impressive sounding but is unable to get around the vertical height issue with the center. He uses a stacked pair of CC5s set horizontally atop a stand with the top of the array at about three feet - just below the line of sight to the screen. 20.1s are used for mains, 3.6s are used for rears along with four Nola subs. Given the width of his 100" screen and that of Room 1, he is unable to use a split center approach. The resolution, however, of that MC audio system is phenomenal.

rw

[Sir Terrence the Terrible]

While you have a great deal of expertise in a wide range of audio topics, these statements are simply not supported by fact. The horizontal dispersion of dipolar planar line sources is anything but identical to that of point sources. Which requires different thinking and placement approaches. Having lived with them for nearly forty years, I am somewhat familiar with their characteristics.

I have no doubt about your knowledge of this type of speaker, you own them. But to say they will NOT have a dispersion interference pattern at some point is simply not true, especially when they are playing the same signal.

Thank you for agreeing! Vertical dispersion is easily solved by using a tall panel. Horizontal dispersion is addressed in different ways depending upon the design. Magneplanars use mirror imaged tweeters and more toe-in to mitigate the effects. My electrostats - which most soundly (pun intended) refute your assertion about dispersion - use angled panels to address the question of horizontal beaming.

Even if you are controlling both the horizontal and vertical dispersion of a speaker, multiples of them tightly spaced together playing the same signal will still have wave interference PERIOD. When you toe these speakers in, the output has to intersect somewhere, and that is where you will experience wave interference. Dipoles Enhance this effect with their reflected energy combining with the direct energy from the speaker. We haven't even discussed the phase interference of this setup. We are talking tightly spaced tri-speaker setups playing a mono signal, not two stereo pairs playing two discrete signals. .

[StevenSurprenant]

Wiring different speakers in series is not ideal. Multiples of the same is fine. An amplifier won't have trouble driving the load, but the time response to the speakers will be affected. I might try using two of the identical speakers as the center with their height aligned with the mains. Just like they do at commercial cinemas.rw

Thanks E-STAT... That answers my question. For all "practical" purposes all the speakers are identical, except the center is curved.

About "challenge with loss of separation", I'm not sure what you mean.

From the seating position the speakers are about equal distant and the information is the same for each of them. It seems to me that this creates a virtual speaker much larger than any one of them. Think of it as a "Very Large Antenna array" that they use for astronomical radio. Same concept, smaller scale. When I move off center the wave form of the separate speakers will begin to diverge causing the lobing that "Sir" mentions. At the same time, the speaker I am closest to will be heard less as I move out of its directional pattern. I doubt that I can detect this minute time delay between the speakers or any lobing that is created, at least I've never heard it.

This is more directed at "Sir" ...

As you are fully aware of, dipole, line arrays, dipole line arrays, box speakers, Multi-driver speakers and about every configuration has its inherent flaws and wave patterns. Throw in different room dimensions and reflecting surfaces, cross talk to both ears from the left and right speakers and you have this incredibly complex wave pattern that is hitting our ears from every direction. It's a wonder that we can hear anything coherent.

"Sir"... Wave interference, combing, lobing, room reflections, speaker directivity, wave patterns from point sources versus line arrays, dipole, bipole, direct radiating speakers, and time alignment is all audio 101. Everyone who has followed this hobby knows this stuff. The only thing that is in contention is the audibility of these affects.

Heck, if I wanted to take it too an extreme, I would build a wall between my speakers right up to my face to prevent the right and left speaker from reaching the wrong ear (cross talk). Even though this cross talk has a large effect on soundstaging and more minor effects on wave interference, it is not worth the effort or concern to address.

As for the integration of my speakers, the distances are set, the volumes are set, and I can't tell where one speaker starts and another begins. This is all good and well, but if you want to be critical, the moment that you move out of the sweet spot, all these setting go out of wack. This occurs on your system and mine. The point is that you are being too critical here.

As for my center channel, where this all began, I've had it above the TV, below the TV, out in the room, and up against the wall. I've sat closer and further away and it sounds like the sound is coming from it and not the screen. You seem to be telling me to live with it, but I have a choice to do other wise.

While I'm at it, I'll tell you one more thing, which I have no doubt that you already know. Frequencies above about 40 Hz are directional and there is no way to hide where the speaker is. You can't make a single speaker sound like it is coming from the screen, but the effect can be reduced by increasing the distance between you and the screen/speaker. That is the only way except for placing the speaker behind the screen or using multiple speakers.

I'm not even sure we are arguing the same point. If speaker articulation (clarity) is your point, then you have nothing to worry about. Clarity of sound has always been my goal since I've gotten into this hobby. I've had Quad electrostats, Magnepan, and more, and built present speakers for my 2 channel system using some of the best components money can buy. I can hear a gnat land on a dogs back with either of my systems. I've also listened to some of the best systems available. Still, I can find fault with any system I've owned and listened to.

Two more things...

My system ( I suppose all) brings the image out into the room as you mentioned that theaters do. regardless of the mechanics, having a deep soundstage behind the speakers is what makes home audio better, it that regard, than a theater. My stereo speakers are about 3 feet from the back wall, but it routinely images 20 feet or more back depending on the source music. My Magnepan speakers are mounted "on the wall" and I still get a very deep soundstage. The imagining is not as precise as my stereo, but I would have to guess that the soundstage is almost as deep. Yet, I do agree that the back wall effects this soundstage.

About lifting the center speaker. It has set directly on top of the TV and almost touching the bottom of the screen with the same results. The eye/ear thingy doesn't work for me. I should mention that my speakers are dipole and long, like line arrays, hence floor bounce is less of an issue. Besides, they only go down to about 100Hz.

Let me ask you a question... Have you ever tried using two speakers for the center channel? Be honest.

I appreciate your thoughts and I know you are trying to help. However, I'm with E-STAT on this issue.

The more I learn, the less I know....

[Smokey]

Wiring different speakers in series is not ideal. Multiples of the same is fine. An amplifier won't have trouble driving the load, but the time response to the speakers will be affected.

Although amp will not have trouble driving the load, but by connecting speakers in series, it does change the electronic characteristic of speakers.

Sonce most amp's speaker out have constant 20 rail volts, by having two speaker in series, the rail voltage cross each speaker will drop to 10 v. Or if three way, the rail voltage cross each speaker will drop to 6.5 volts. So a speaker that have 20 volts cross it will sound different (since its electronic specification has change) than the one that have 10 volts or 6.5 volts cross it. So you are basically "starving" your speakers.

I tried two speakers in series, and notice that not only it pretty much kill speakers bass responce, it made them sound lifeless. Sounded like cheap car speakers

[E-Stat]

I have no doubt about your knowledge of this type of speaker, you own them. But to say they will NOT have a dispersion interference pattern at some point is simply not true, especially when they are playing the same signal.

Who is it who made such a claim? What I did was observe that your sweeping statement (completely independent of the OP's question) that there is NO difference in horizontal dispersion between point source speakers and dipolar panel line sources is most certainly not a correct assertion.

Even if you are controlling both the horizontal and vertical dispersion of a speaker, multiples of them tightly spaced together playing the same signal will still have wave interference PERIOD.

You seem to be caught in a negative feedback loop. While your point has been restated, you have returned to post #11 - to which I responded in advance in post #10. Let's review the facts:

1. Optimum center channel speaker arrangement is uniquely found in the cinema environment employing vertical symmetry of the three front channels.
2. Most HT arrangements don't allow for what is known to be ideal.

Pick your own poison by determining which parameter you choose to optimize over another.

rw

[E-Stat]

Although amp will not have trouble driving the load, but by connecting speakers in series, it does change the electronic characteristic of speakers.

Isn't that essentially what I said in the two sentences you quoted?

I tried two speakers in series, and notice that not only it pretty much kill speakers bass responce, it made them sound lifeless.

For starters, bass response for the voice track really isn't that critical. You might be surprised how many speakers use series wired components. Aren't you one of the Roger Russell disciples? You do realize that his IDS speaker is wired thusly, right?

rw

[E-Stat]

Thanks E-STAT... That answers my question. For all "practical" purposes all the speakers are identical, except the center is curved.

They are not identical. Why does the center cost only $26 less than the pair of MMG-Ws?

About "challenge with loss of separation", I'm not sure what you mean.

You have effectively split the mono center channel into two parts which are located closer to the mains reducing the effective separation between main and center.


rw

[StevenSurprenant]

They are not identical. Why does the center cost only $26 less than the pair of MMG-Ws?

You have effectively split the mono center channel into two parts which are located closer to the mains reducing the effective separation between main and center.rw

I'm not sure about the price difference. Why does any center channel cost more than a single main speaker?

From what I understand, they are the same driver. On the MMGW the panel is laid flat in it's frame while on the MMGC the same panel is stretched on a curved frame. If you look at the specs, they are identical.

Description Planar Magnetic
Freq. Resp. 100 Hz- 16 kHz + - 3 db
Sensitivity 88 db 2.83 volts
Impedance 5 ohms

They sound similar, but not totally the same.
__________________________________________________ _
"challenge with loss of separation" - I understand now and I was concerned about that. What I discovered was that the image was still in a relatively tight point in the center of the screen from left to right instead of spread out like what someone might imagine.

I suppose that it's like a 2 channel system that is playing a mono source. In my stereo room I have a smaller TV between the speakers and when I am watching an older movie with a mono source it seems like all of the sound is coming directly from the TV and that the main speakers are off. In other words, the sound is confined to a very tight point between the speakers.

Thinking further about that... If the speakers are angled correctly, as I move away from the center, I am also moving away from the radiation pattern of one speaker while remaining in the radiation pattern of the other, hence preventing image drift. As you know, dipoles have a null region at edge of their speaker plane.

I suppose that in the extreme, as long as you remain in the center between speakers (to prevent image drift), the two side center channel speakers could be placed right next to the mains and still produce a very distinct focused image midway between the mains. Even in this scenario, If the speakers radiation pattern is optimal and the speakers are angled correctly, it should still be able to maintain a focused center image when moving away from the center.

While we're talking...

There has been much talk about point sources being the optimal type of speaker. It sounds good in theory, but it has a major flaw and that is listening distance. The closer you are, the smaller the image. I'll give you a real life example. I have a recording of Peter Paul and Mary which uses a great deal of hard left and right. In certain songs, Peter is singing directly out of one speaker and Paul is singing out the other. The surface area of my Quads is a great deal larger that what I use now and when I play those tracks, the image of the voices appear much larger on the Quads than on my present system. My present system has a relatively smaller point source on the horizontal plane than the Quads. Hence, while the image height is about the same between the two speakers, image width is much broader on the Quads. I imagine that if I could sit further from my present speakers, this might change. I prefer the Quads on that CD. One of the selling points of the Quads is that it is a point source, but at a perspective of sitting further from the point source. I'm not being clear here, but hopefully you will understand.

The reason I mention this is because the Maggies tend to create a broader/taller image across the screen compared to using a smaller speaker. If I were to use smaller point source speakers for the center, the image would be more focused into a point on the center of the screen. As it is, the image is about the size of my screen. I don't know if that's better, but I like it.

The other thing, and as a electrostat aficionado you should know, is that most box speakers sound like boxes. You and I can hear the boxes, but people who don't listen to dipoles can't hear it. To me, it's in your face. That doesn't mean that dipoles are the better than box speakers. They both have their strengths.

I've heard some great speakers in my days, Quads, Martin Logan, Theil, Avalon, Wilson, and too many others to mention. Even my Phase linear's (dipole) from the 70's were impressive in their clarity. The one thing in common with all great speakers is that the first thing I noticed was the music in all its grandeur and delicacy. The speakers and electronics became invisible until the song ended.

Thanks for your thoughts, it helps me think and understand. Keep in mind that I'm not always right. As I said in a previous post, "the more I learn, the less I know."

[Feanor]

...
Two speakers reproducing the same signals introduces dispersion pattern interference that is not very good for dialog clarity.

...

I don't understand the implications of this for stereo. Of course we know that the central image in a stereo sound stage consists of the same sound coming from both left and right speakers. Isn't there dispersiona pattern interference in this case? But subjectively the central image -- singer, solo instrument -- sounds pretty good.

[E-Stat]

If you look at the specs, they are identical.

FR and efficiency, yes. Size and panel configuration, however, are different which most likely yields a slightly different radiation pattern.

rw

[StevenSurprenant]

Although amp will not have trouble driving the load, but by connecting speakers in series, it does change the electronic characteristic of speakers.

Sonce most amp's speaker out have constant 20 rail volts, by having two speaker in series, the rail voltage cross each speaker will drop to 10 v. Or if three way, the rail voltage cross each speaker will drop to 6.5 volts. So a speaker that have 20 volts cross it will sound different (since its electronic specification has change) than the one that have 10 volts or 6.5 volts cross it. So you are basically "starving" your speakers.

I tried two speakers in series, and notice that not only it pretty much kill speakers bass responce, it made them sound lifeless. Sounded like cheap car speakers

Good points!

My electronics knowledge is very limited, but I sort of know what you are saying. As a corollary of what you have said, does that imply that by running speakers in parallel at 4 ohms , the speakers should sound even better? I'm not being facetious, I really don't know. If I were to guess, I would think that, in parallel, there would be 20 volts across both speakers and the amp would just double the current output with no change in sound, except for the 3 db increase by having two speakers instead of one. It does make sense that more impedance means less current, but if we were speaking about the amount power needed for a certain db output, this could be attained by increasing the voltage to the output transistor gate. Ahhh... I understand now... By wiring three speakers in series, the maximum power across any one speaker would be P = V squared / R.

As an example... P = 20 volts squared/5 ohms = 80 watts for a single speaker, but in series... P = (20/3)squared / 5 ohms = 8 watts per speaker. Does that sound correct?

Now considering my speakers... They are rated down to 100 Hz at which point I assume the impedance increases, so power is not wasted below that point. I have the speakers set to small and the crossover set to 200 on them so that I have 8 watts of electrical power available to drive each speaker from 200Hz to 16kHz. Besides that, by running three speakers, each additional speaker adds a 3db increase in acoustic power for a 6db increase.

In total, I have 8 watts of electrical power available but the 6db acoustic output gained by using 2 additional speakers gives me the equivalent acoustic power of 32 watts. In other words, I would get the same output running one speaker at a maximum of 32 watts. Does this make sense? This reduces the acoustic output by about 4db compared to running a single speaker at 80 watts. Since my speaker efficiency is 88db this limits the maximum output to about 106db in a tri-speaker configuration. I'm not sure that my speaker can put out that amount of sound pressure. So, in the practical sense, I'm good to go.

Does this make any sense to you?

Thank you.