Are your speakers losing air?


I was reminded of my own advice today.  I was fiddling with something in my HT system and had my head right up to the center channel.  I noticed that sadly, there was a lot more air and ambiance up close to the center speaker than at my listening location. 

I remembered the advice I often give others about room treatment.  If you sit up close to your speakers you can really hear the detail and ambiance they create, and that all the information you lose between there and your normal listening position is due to the room.  That is, your room is lossy. 

In this particular case I resolved the issue by putting a 2'x4' acoustic absorber across the entertainment center, essentially hiding it entirely with the center peeking up above it.  Problem solved, and suddenly movies and dialogues have a lot more acoustic information than they used to. 

This also shows us a couple of other issues.  My center is, by deliberate design, extremely wide dispersion.  I am most likely suffering from this vs. say a horn loaded center like Hsu or Klipsch offer.  That is, a limited dispersion center may not have had these issues.  The other is that my Butcher Block double wide rack is itself a source of interference with the original signal.  This I may fix more permanently with an IR repeater so I can keep the panel in place. 

Anyway, hope this advice helps you in evaluating how to get the most out of your speakers and room.

erik_squires

I eliminated my center channel problem decades ago.

I got rid of the center channel.

Simplicity. 

I know that’s probably not the answer you were looking for. 😬

Lost here is the obvious observation of speaker diffraction off the table top of the equipment cabinet typical in these setups.

The diffraction generates more and more interfering energy which becomes part of the wave launch though never in time with the voice or the music. That is unless the speaker is mechanically grounded to the higher mass of the cabinet. So called isolation devices  themselves are another form of delayed storage like a capacitor. TomD

@deep_333 The concentric drivers are also very interesting ideas here.

The big challenge for a center is you want to have the dispersion of a 3-way speaker, but the height of 1 woofer! It’s a compromise achieved in a variety of ways. Sometimes with very very small midranges and/or very low profile tweeters but the concentric design is also a good fit here.

The negative for concentric is the doppler shift that happens, especially in a smaller concentric. Still, it is undeniably a good possibility for a low-height, 3-way center channel, or even a less ambitious 2-way with a single concentric.

You’d be shocked at how many well known and well respected, center channel speakers have horrible off axis speaker performance, and measurements.

A good friend and I, spent several weekends measuring every center channel speaker we could beg, borrow or steal. And we were pretty consistently in a state of disbelief.

And it’s not as if getting decent vertical and horizontal off-axis response is some majore engineering task.

A well designed concentric driver design is a great fit for Center channel applications. I use a specific Andrew Jones design with the bass drivers crossed over at 200hz...and it works like a charm.

The advantage of a concentric driver (to begin with) is quite well known...It doesn’t have to be all that difficult to find a center channel that just works, if you do your fair share of thinking beforehand.

Same old soup. No new creative solutions hear. Where is Maghister when he’s needed. The Music Fan works wonders if you choose the correct fan and place it in the right location and treat the blades with the right materials. And turn it in the right direction. TomD

 

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Well @tvad  - I guess you solved it for everyone!!  I mean, yes, listening nearfield solves the problem if you can listen or want to listen nearfield.

 

Otherwise, EQ the missing frequencies by adding a 3dB-6dB boost.

EQ and room treatements have some areas in which they overlap which is in changing the overall tonal balance, but they are not entirely replaceable with each other.  To use a visual metaphor, you can change the color balance with EQ but not detail like you can with room treatments.

As you increase the treble, you also increase the early reflections, so your signal-to-noise remains constant.  By absorbing early reflections you actually improve the signal to noise ratio. 

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Several readers replies make me think that they missed the solution here:

Eliminate early reflections

A principle that can be applied to any speaker.

You’d be shocked at how many well known and well respected, center channel speakers have horrible off axis speaker performance, and measurements.

@simonmoon  That's why I built my own.  😁

 

@moonwatcher  I think you touched on several issues aboout how the home center channel is always a compromise.  In m y case while. the off axis performance is excellent, I don;t have floor space to put it in anywhere but on top of the audio rack, and hence the excellent vertical dispersion is a double edged sword.

 

The nature of the beast. Most center channel speakers are more or less "regular" speakers turned 90 degrees on their sides, so yes, there's bound to be issues with dispersion. You might get them to sound great to you, sitting in the sweet spot, but for anyone sitting a few feet off axis, not so much. 

I'm surprised more center channel speakers aren't coaxial to improve that even dispersion in the room at least +/- 30 degrees, but we get what is offered by the manufacturers. 

Even a MTM speaker will have issues.  So we are left with narrow beaming to sound good in a very narrow spot or attempting to spread that higher frequency information more evenly somehow through the room. 

Most people WANT the long form factor of a center speaker because it fits easily under their TV and their wives thinks it looks "OK". And there may already be a rack of equipment or a coffee table under the TV.  Trying to convince the spouse to accept yet another "big" speaker under the TV is problematic. @mashif glad you can get away with it. 

I have vintage 12" 3 way JBLs for LCR. Each has volume controls for midrange and tweeter. I set them by ear and then run Audyssey. The end result is very clear and powerful sounding dialogue. Larger speakers push more air farther into the room.

...that's what and why I've blown off treading into adding a center channel config into my current array (omni 'surround' with a sub front at the cl 'up front')...

What happens if you increase the gain to the center drivers?  Does it muck it up, or improve the 'imaging'?

Curious minds get more curious overtly over time... ;)

It’s not just the room. The higher the frequency, the more it attenuates with distance as it is absorbed by the atmosphere, slightly heating it in doing so. This goes beyond "spreading losses."

You’d be shocked at how many well known and well respected, center channel speakers have horrible off axis speaker performance, and measurements.

A good friend and I, spent several weekends measuring every center channel speaker we could beg, borrow or steal. And we were pretty consistently in a state of disbelief.

And it’s not as if getting decent vertical and horizontal off-axis response is some majore engineering task.

So, it does not surprise me at all that it sounded better when you were up close.

Luckily many improved just by tilting them up a bit. But some were so bad, they actually sounded better set vertically. 

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You can add 1 of my Music Fans behind your listening position.

Reduces interfering energy around furniture and big heads in the way. TomD