Most important metrics for home theatre

[pepito]

After watching Erin's video at Erin's Audio Corner about the differences between the criteria when selecting speaker for home theatre use and for music listening, I thought I'd open a discussion here to see what other people thought. In summary, Erin pointed out that for home theatre preference should be given to the following metrics:

• Speaker Output - Capability of handling louder volumes without compression and distortion
• Early Reflections Directivity Index - Relatively smooth line so that speakers can be EQ'd
• Linear Frequency Response - Erin makes an interesting point that people are more likely to be distracted by the action on screen so less likely to notice small deviations from the ideal curve. Anyway, if a speaker has a relatively smooth ERDI you can smooth out the response with EQ.

So, what are the thoughts of the members of this forum regarding the most important metrics for home theatre? Are there any other considerations that one should make when shopping for home theatre speakers?

 

[phoenixdogfan]

Since it's likely home theater is for more than one listener, even bass response at all listening positions, infrasonic bass, and dialog intelligibility (don't know how that's objectively measured, but it's very important).

 

[Dj7675]

After watching Erin's video at Erin's Audio Corner about the differences between the criteria when selecting speaker for home theatre use and for music listening, I thought I'd open a discussion here to see what other people thought. In summary, Erin pointed out that for home theatre preference should be given to the following metrics:

• Speaker Output - Capability of handling louder volumes without compression and distortion
• Early Reflections Directivity Index - Relatively smooth line so that speakers can be EQ'd
• Linear Frequency Response - Erin makes an interesting point that people are more likely to be distracted by the action on screen so less likely to notice small deviations from the ideal curve. Anyway, if a speaker has a relatively smooth ERDI you can smooth out the response with EQ.

So, what are the thoughts of the members of this forum regarding the most important metrics for home theatre? Are there any other considerations that one should make when shopping for home theatre speakers?

-Adequate dispersion for all speakers but special attention to the center if you have seats quite a bit off axis
-Speakers can be aimed at listeners. For example if doing Atmos many will go with an in ceiling that is pointing straight down at the floor instead of a model with an angled baffle or a bookshelf speaker with a bracket to point the speaker at the main listening position.
-Special attention to the speaker output you mention already. If you are truly attempting to replicate the theater at home, you really have to select your speakers carefully with that in mind. So have in mind the peak SPL you want your speakers to be able to handle and pick accordingly. Trying to get a speaker that can do 100-105dB peaks at 10-15 feet isn't something any speaker can do without distortion or compression becoming an issue.
-

 

[Ericglo]

I am not sure if it has been answered or not. I would think a narrower directivity as opposed to an ultra wide would be better.

 

[Timcognito]

Use of surround dipole speakers on sides and above near seating positions to create null spots.

 

[Inner Space]

So, what are the thoughts of the members of this forum regarding the most important metrics for home theatre? Are there any other considerations that one should make when shopping for home theatre speakers?

More of a mental concept than a measurable metric, but - the center speaker is the most important. In fact there's a plausible argument that it's the only important speaker. Put most thought and budget there.

 

[Dj7675]

More of a mental concept than a measurable metric, but - the center speaker is the most important. In fact there's a plausible argument that it's the only important speaker. Put most thought and budget there.

Not my experience. I will sometimes watch level meters while watching a movie. While there is a lot of activity of course on the center, the L/R have peak levels all the time as high as the center. Whether it is action sequences or movie soundtracks or special effects, those peaks are there and if you don't have speakers that can handle those same peaks the experience is lacking IMO. This can really even extend to surround and Atmos is many movies. Dolby spec is for all speakers to be capable to hit 105dB at the MLP. Gone are the days where surround speakers are just for ambiance. So while the center can and is very busy the L/R are commonly at those same peak levels quite a lot of the time and even surround and Atmos (although not as often). I would just encourage people planning not to underestimate the SPL needed for all speakers and not just the center...

 

[Inner Space]

Not my experience. I will sometimes watch level meters while watching a movie. While there is a lot of activity of course on the center, the L/R have peak levels all the time as high as the center. Whether it is action sequences or movie soundtracks or special effects, those peaks are there and if you don't have speakers that can handle those same peaks the experience is lacking IMO. This can really even extend to surround and Atmos is many movies. Dolby spec is for all speakers to be capable to hit 105dB at the MLP. Gone are the days where surround speakers are just for ambiance. So while the center can and is very busy the L/R are commonly at those same peak levels quite a lot of the time and even surround and Atmos (although not as often). I would just encourage people planning not to underestimate the SPL needed for all speakers and not just the center...

Good answer, and obviously, if you can, you should optimize everything. But always remember, virtually the entire narrative content of a movie is in the center channel, so its clarity and coverage is paramount. Imagine your new puppy chewed through every wire except the center. You would still enjoy the movie. The opposite isn't true. Therefore, the choice between a great center and an adequate 4.1 -vs- an adequate center and a great 4.1 is a no-brainer. Too many people - and manufacturers! - settle for centers-as-afterthoughts, whatever fits, etc, etc. Which is a shame, because it's the most important component. We're sending everything to it, except for peripheral fluff.

 

[Mr. Widget]

After watching Erin's video at Erin's Audio Corner about the differences between the criteria when selecting speaker for home theatre use and for music listening, I thought I'd open a discussion here to see what other people thought. In summary, Erin pointed out that for home theatre preference should be given to the following metrics:

• Speaker Output - Capability of handling louder volumes without compression and distortion
• Early Reflections Directivity Index - Relatively smooth line so that speakers can be EQ'd
• Linear Frequency Response - Erin makes an interesting point that people are more likely to be distracted by the action on screen so less likely to notice small deviations from the ideal curve. Anyway, if a speaker has a relatively smooth ERDI you can smooth out the response with EQ.

So, what are the thoughts of the members of this forum regarding the most important metrics for home theatre? Are there any other considerations that one should make when shopping for home theatre speakers?

I think Erin got it pretty much spot on.
In my day job I design a lot of theaters and media rooms, so I have a fair amount of experience in choosing speakers for these rooms.

Regarding early reflections, in our dedicated rooms we can usually control the early reflections in the design of the room, but speakers with well behaved DI is still desirable. In a room where we can not control the early reflections, we usually choose speakers with a very controlled horizontal pattern.

Regarding the sound quality of the speakers, we certainly prefer neutral speakers, but will trade off a little in this regard for dynamic capabilities.

Regarding the importance of the center channel, ideally this speaker will have a similar sonic signature with the left and right front speakers to help give a seamless front sound. (Three identical speakers is best.) Since most soundtracks use the center channel primarily as a dialog speaker with the left and right channels covering more of the music and the rest of the soundtrack, the center should have wide enough dispersion to cover the entire seating area, but can have a slightly less extended frequency response if required by real estate or cost reasons.

Regarding subwoofers, the best practice to achieve even bass from seat to seat is the use of multiple subs. We rarely use less than 4. Yesterday I was at one of our DCI rooms with the video calibrator and he told me about a recent project he was on that had 12 subs including ceiling subs. This was a very high end room with Meyer Sound Bluehorns for LCR and L&R Wides.

 

[Ken1951]

Changing out bookshelf Focals and an MTM center - all too small for our great room - for larger speakers, but more importantly a much larger 3-way center channel made a huge difference to our listening experience. The L/R speakers are great, but my wife can hear dialogue so much better than before due to the improved center.

 

[pepito]

I am not sure if it has been answered or not. I would think a narrower directivity as opposed to an ultra wide would be better.

By directivity I assume you mean the early reflections directivity index?

 

[pepito]

Use of surround dipole speakers on sides and above near seating positions to create null spots.

If you were creating an Atmos system, say a 5.1.4 or 7.1.4 system wouldn't dipole speakers negatively impact the Atmos experience?

 

[Timcognito]

If you were creating an Atmos system, say a 5.1.4 or 7.1.4 system wouldn't dipole speakers negatively impact the Atmos experience?

Maybe but if one puts a speaker right next to or above a seat or end of a couch then that's all that viewer hears. Dipoles fix that issue. Room and seating dynamics are as important as gear. I should have started with that.

 

[pepito]

I think Erin got it pretty much spot on.
In my day job I design a lot of theaters and media rooms, so I have a fair amount of experience in choosing speakers for these rooms.

Regarding early reflections, in our dedicated rooms we can usually control the early reflections in the design of the room, but speakers with well behaved DI is still desirable. In a room where we can not control the early reflections, we usually choose speakers with a very controlled horizontal pattern.

Regarding the sound quality of the speakers, we certainly prefer neutral speakers, but will trade off a little in this regard for dynamic capabilities.

Regarding the importance of the center channel, ideally this speaker will have a similar sonic signature with the left and right front speakers to help give a seamless front sound. (Three identical speakers is best.) Since most soundtracks use the center channel primarily as a dialog speaker with the left and right channels covering more of the music and the rest of the soundtrack, the center should have wide enough dispersion to cover the entire seating area, but can have a slightly less extended frequency response if required by real estate or cost reasons.

Regarding subwoofers, the best practice to achieve even bass from seat to seat is the use of multiple subs. We rarely use less than 4. Yesterday I was at one of our DCI rooms with the video calibrator and he told me about a recent project he was on that had 12 subs including ceiling subs. This was a very high end room with Meyer Sound Bluehorns for LCR and L&R Wides.

What do you look at when you want to see if a speaker has good dynamic capabilities? What metrics/graphs do you focus on?

I'm looking for speakers for my own home theatre setup. What speakers do you recommend in the budget category? This will be my first home theatre setup so will be starting off with a 2.1 setup and then expanding to 5.1/7.1. My budget is $250 for the left and right speakers and $300 for the subwoofer.

 

[Ericglo]

By directivity I assume you mean the early reflections directivity index?

No I mean a speaker that has wide dispersion like Philhamonic BMR vs something narrow like a horn.

 

[pepito]

No I mean a speaker that has wide dispersion like Philhamonic BMR vs something narrow like a horn.

That's interesting. I always thought that wider is better. A bigger sweet spot to experience the best sound.

 

[Chrispy]

That's interesting. I always thought that wider is better. A bigger sweet spot to experience the best sound.

Depends on room somewhat.....

 

[Mr. Widget]

What do you look at when you want to see if a speaker has good dynamic capabilities? What metrics/graphs do you focus on?

I'm looking for speakers for my own home theatre setup. What speakers do you recommend in the budget category? This will be my first home theatre setup so will be starting off with a 2.1 setup and then expanding to 5.1/7.1. My budget is $250 for the left and right speakers and $300 for the subwoofer.

I am not aware of published specs that will help with determining a loudspeaker's dynamic capabilities. Dynamic compression occurs when SPL increase is not linear with power input due to voicecoil heating, additionally there are micro dynamics which are related to the design and type of the drivers themselves. Ideally you want an infinitely light moving mass and infinitely powerful motor. That being the ideal, the closer you get to it the better.

With such a limited budget, I think you would do best with a 2.0 system initially. Get better left and right speakers initially and then add the subwoofer when you can fit it in your budget. Be aware that most low cost subs and many more expensive subs have internal amplifiers that over time are not very reliable so keep that in mind too.

 

[pepito]

I am not aware of published specs that will help with determining a loudspeaker's dynamic capabilities. Dynamic compression occurs when SPL increase is not linear with power input due to voicecoil heating, additionally there are micro dynamics which are related to the design and type of the drivers themselves. Ideally you want an infinitely light moving mass and infinitely powerful motor. That being the ideal, the closer you get to it the better.

With such a limited budget, I think you would do best with a 2.0 system initially. Get better left and right speakers initially and then add the subwoofer when you can fit it in your budget. Be aware that most low cost subs and many more expensive subs have internal amplifiers that over time are not very reliable so keep that in mind too.

I’ve just purchased a pair of the Emotiva Airmotiv B1+ based on all the positive reviews. Do you think this is a good buy? The other three I was looking at were the JBL A130, the Polk XT20 and Elac Debut B5.2.

Regarding the subwoofer and integrated amp, I’ll take that on board. Which budget subwoofer would you recommend?

 

[Mr. Widget]

I’ve just purchased a pair of the Emotiva Airmotiv B1+ based on all the positive reviews. Do you think this is a good buy? The other three I was looking at were the JBL A130, the Polk XT20 and Elac Debut B5.2.

Regarding the subwoofer and integrated amp, I’ll take that on board. Which budget subwoofer would you recommend?

Unfortunately, I am not a budget equipment expert. I think the SVS line of subs offer great value, but my only experience with them is through reading about them on line. There are many others who have much more experience in this area.

Good luck in your quest!