Center channel advice, discussion & measurements

[AnonymousAudio]

So I was recently back in the market looking for a new Center Channel and learned about a few modern tips and research that I was hoping to share and further discuss with anyone thats interested.

I'd like to stay focused primarily around Horizontal Centers. As its been previously discussed that the best option is to use another Bookshelf or Floorstanding speaker as a center. However for many of us this isn't an option for numerous reasons from space and practicality to the WAF (Wife Acceptance Factor)

Keeping that in mind one thing that's of high importance is finding a center that has good off-axis performance. Which is very important so that people not sitting in the sweet spot can clearly hear voices which remain intelligible.

One thing to watch out for is Lobing, This is where some drivers will actually be out of alignment and gets worse the further off-axis you get. This can cause a Nulling effect which esentially cancels out certain frequencies. Causing dialog to drop out considerably. Below I attached a speaker measurement which illustrates this effect.

Also Erins audio corner on youtube has done a great job explaining how this works and which design are the best choices to look out for. One thing however that wasn't mentioned is a newer method to prevent the Lobing effect. Martin Logan for example uses this technology on their C100. The way they accomplish this is to have the mid/bass drivers on either side of their tweeter to be Crossed-over at different frequencies. One at 1300hz and the other at 2500hz. This method makes those wide Centers a viable option to choose from again. And I hope other Brands adopt this anti-lobing method for their existing Centers with issues or uses a better Design altogether as Erin recommends, because right now theirs not a lot of viable options available out there.

Link to Erins video:

 

[Kal Rubinson]

One thing however that wasn't mentioned is a newer method to prevent the Lobing effect. Martin Logan for example uses this technology on their C100. The way they accomplish this is to have the mid/bass drivers on either side of their tweeter to be Crossed-over at different frequencies. One at 1300hz and the other at 2500hz. This method makes those wide Centers a viable option to choose from again.

This does not seem to be a solution as it may only make the lobing asymmetrical. Aside from M-L literature, is there a link to a study or paper?

 

[AnonymousAudio]

This does not seem to be a solution as it may only make the lobing asymmetrical. Aside from M-L literature, is there a link to a study or paper?

Thats what I was hoping to dive into further. As you prob know that ML lineup was released in 2023. So its fairly new. But I haven't seen any off-axis measurements done by any reviewers yet to show how much this improves on this Lobing issue. In theory I can see the benefits. And in their own literature it states a "significant reduction".

I've personally went to my local B.B store and auditioned them to see if this was the case by standing off to the sides then comparing them to similar centers and noted that it sounded more intelligible to my ears. But of course thats an anecdotal account.

I was hoping that someone out there could possibly test this if they have the means or refer this over to Erin...as I think it would make a good follow up to his now 3yr old video that came out before Martin Logans anti-lobing design was released.

 

[Kal Rubinson]

In theory I can see the benefits.

Seems like a gimmick.

 

[Sancus]

Martin Logan for example uses this technology on their C100.

$1500 US for a 2(.5)-way center is a lot of money, IMO. This should be a 3-way and what they've done is a cost cutting measure if anything.

 

[AnonymousAudio]

Seems like a gimmick.

Changing crossovers by default would automatically cancel out any doubling effect between (1300hz & 2500hz) thus eliminating the Null between these frequencies. So that makes sense from an acoustical theory perspective. And would further explain why they stopped short saying "significant reduction". Thus meaning between those frequencies which would be most beneficial towards preserving dialog. That's the way I understand it. Saying it's a gimmick doesn't give me anything to logically discuss, except to imply your disbelief and opinion. As I mentioned previously it would be nice to see this verified further with measurements from someone with the means to prove it one way or another. But it does make sense, how it could work and why I heard a difference between similar speakers of different Brands.

 

[AnonymousAudio]

$1500 US for a 2(.5)-way center is a lot of money, IMO. This should be a 3-way and what they've done is a cost cutting measure if anything.

It's not about the price...this is more of a discussion about the method used in the Crossover design. Imagine having a speaker at a fraction of that cost say $500 that's more towards your preference, except it's using this technique of using multiple crossovers on similar Mid/Bass drivers. Wouldn't you like to know that you would be getting a center without Lobing at certain frequencies... If this method proves to be effective wouldn't it benefit us all to be replicated on other such Center Channels?

 

[Blumlein 88]

Centers are a real problem. The horizontal layout is basically the worst for a center. You need a good center is it handles by far the majority of the output. Generally 6 db more in centers vs right and left. I floorstander preferably as large as or larger than the right and left fronts would be good. A big coaxial with a sub added even better. Yet with a screen right in the middle this doesn't work or/and the coax is expensive.

If this ML idea works it seems it can only be a partial help. I've though maybe a near full range rectangular horn might work. Or an array of multiple drivers with time delay in a horizontal form. Of course all of those would also be expensive.

To answer the OPs question, you'll need a spin test of the ML. I doubt it will be more than partially effective.

 

[Heatransfer]

It's about price. Or perhaps more precisely, it's about design trade offs.

There are already very good solutions to off axis cancellation created by a MTM setup. (Examples include coaxial drivers like kef, or a stacked tweeter and mid like Revel does on the c208 and PerformaBe or Paradigm does on their midline series on up).

These inherently avoid the issues with destructive cancellation in the voice frequencies.

The trade-off is price, and in many cases size.

Keep in mind that using this 2.5 crossover design costs more than just with a straight 2way MTM - there's the extra cost of parts (crossover parts) and the two midwoofers may be different in design. So if we 'work upwards' and add this as a feature to a cheaper design, suddenly that design isn't so cheap anymore.

 

[AnonymousAudio]

It's about price. Or perhaps more precisely, it's about design trade offs.

There are already very good solutions to off axis cancellation created by a MTM setup. (Examples include coaxial drivers like kef, or a stacked tweeter and mid like Revel does on the c208 and PerformaBe or Paradigm does on their midline series on up).

These inherently avoid the issues with destructive cancellation in the voice frequencies.

The trade-off is price, and in many cases size.

Keep in mind that using this 2.5 crossover design costs more than just with a straight 2way MTM - there's the extra cost of parts (crossover parts) and the two midwoofers may be different in design. So if we 'work upwards' and add this as a feature to a cheaper design, suddenly that design isn't so cheap anymore.

Okay then lets factor in your real world price. Can you show me a Center channel around $1,500 that can match the ML C100's frequency response going down to 42hz (+/-3dB) - 25khz ? Cause if theirs another Center out there that's capable as a 3way and has comparable Towers in their lineup i'd be most interested in checking them out...any suggestions around that price?

 

[Titurel]

I've had a bunch of different center channels - none very satisfactory, until the last one, a Revel C426Be. It may not be perfect, but its configuration - a small vertical 2-way, centered in an horizontal array of 4 mid-bass/woofers - works better (in my room) than anything else I've had in its place.

​

 

[AnonymousAudio]

I've had a bunch of different center channels - none very satisfactory, until the last one, a Revel C426Be. It may not be perfect, but its configuration - a small vertical 2-way, centered in an horizontal array of 4 mid-bass/woofers - works better (in my room) than anything else I've had in its place.

​

Thats $5k for that Center over 3X the price. We talked earlier about design trade offs and price. Looks like a 2.5 way with anti-lobing is looking pretty good right about now.

 

[Heatransfer]

Okay then lets factor in your real world price. Can you show me a Center channel around $1,500 that can match the ML C100's frequency response going down to 42hz (+/-3dB) - 25khz ? Cause if theirs another Center out there that's capable as a 3way and has comparable Towers in their lineup i'd be most interested in checking them out...any suggestions around that price?

Are you planning on running a subwoofer?

If so, you do not need that much bass extension. If not, you should

For all I know this may be the only center channel product, at this MSRP, that extends this low. If we're talking about design trade-offs, I prefer that a CC prioritizes vocal reproduction over bass extension.

I don't know every speaker out there, but there are many products within this price range that will extend well into the 65hz range (that is, very safely into the typical 80hz crossover frequency) that use a 3way design.

 

[Sancus]

It's not about the price...this is more of a discussion about the method used in the Crossover design. Imagine having a speaker at a fraction of that cost say $500 that's more towards your preference, except it's using this technique of using multiple crossovers on similar Mid/Bass drivers. Wouldn't you like to know that you would be getting a center without Lobing at certain frequencies... If this method proves to be effective wouldn't it benefit us all to be replicated on other such Center Channels?

I'm not really sure why it would reduce lobing. It seems more likely to shift the two lobes so they're asymmetric, as Kal suggested. Their marketing states it *eliminates* lobing, but not how. I find it very strange they make a very specific claim about measurements but don't publish any at all.

In any case, to see for sure someone will have to buy one and send it in for review. That's how it works.

If for some reason this works, cool, but you should always be very skeptical about unproven manufacturer claims especially when it would be pretty easy for them to publish some amount of proof...

 

[Anton S]

...

There are already very good solutions to off axis cancellation created by a MTM setup. (Examples include coaxial drivers like kef, or a stacked tweeter and mid like Revel does on the c208 and PerformaBe or Paradigm does on their midline series on up).

These inherently avoid the issues with destructive cancellation in the voice frequencies.

...

Indeed! I've been very satisfied with my old 3-way JBL Studio S-Center for some time now. Its horizontal dispersion is great, and its sensitivity matches that of my main L/R towers, which is important for maintaining overall channel-to-channel loudness balance. (In fact, I've been careful to match the sensitivities of all the passive speakers in my system to within 0.5 dB of one another, so the overall system balance remains intact when I increase/decrease the volume.)

The Studio S-Center was a genuine bargain at around $500 USD when it was still available (but is now discontinued). Excellent materials, build quality, and performance. It is rated +/- 3dB only down to 80 Hz, but that's an honest rating, as measured by REW. Bass management and my SVS take care of the bottom end.

 

[AnonymousAudio]

Are you planning on running a subwoofer?

If so, you do not need that much bass extension. If not, you should

For all I know this may be the only center channel product, at this MSRP, that extends this low. If we're talking about design trade-offs, I prefer that a CC prioritizes vocal reproduction over bass extension.

I don't know every speaker out there, but there are many products within this price range that will extend well into the 65hz range (that is, very safely into the typical 80hz crossover frequency) that use a 3way desihave a very capable SVS sub...

I'm not really sure why it would reduce lobing. It seems more likely to shift the two lobes so they're asymmetric, as Kal suggested. Their marketing states it *eliminates* lobing, but not how. I find it very strange they make a very specific claim about measurements but don't publish any at all.

In any case, to see for sure someone will have to buy one and send it in for review. That's how it works.

If for some reason this works, cool, but you should always be very skeptical about unproven manufacturer claims especially when it would be pretty easy for them to publish some amount of proof...

To be clear lobing happens when two speakers playing the same frequency collide abd cancel eachother out. So if one driver in a pair has a X-over at 1300hz then that means your left with only 1 driver producing up to 2500hz. This eliminates lobing inside these freq ranges as theirs only a single driver playing them. And this freq range is important for Vocals so its pretty effective. I heard this when i listened to this Center and it sounded great. I was comparing it to a KEF R6 which is a coaxial design. It sounded literally "hollow" to me. Which if anything going in I was expecting to like the KEF more...so it wasn't bias it surprised me how much better the C100 sounded.

 

[AnonymousAudio]

Are you planning on running a subwoofer?

If so, you do not need that much bass extension. If not, you should

For all I know this may be the only center channel product, at this MSRP, that extends this low. If we're talking about design trade-offs, I prefer that a CC prioritizes vocal reproduction over bass extension.

I don't know every speaker out there, but there are many products within this price range that will extend well into the 65hz range (that is, very safely into the typical 80hz crossover frequency) that use a 3way design.

I have a SVS SB17 should be enough Bass. However having a Center that can play below 50hz is a plus. The only reason THX likes to use 80hz for home theater crossovers is because most cant handle anything close to full range. Do you think theaters crossover at 80hz on their Centers...i dont think so. So the closer i can get to full range within my budget I will go for thats my preference.

 

[rynberg]

Honestly, this seems like you hardcore angling (or shilling, if I were being more honest) that Martin Logan's poorly engineered speakers are somehow great technology. What they are doing isn't innovative or new in any way and will absolutely still have lobing in a critical frequency range. The other speakers in this line have nasty resonances, completely aside from the very non-linear frequency response.

 

[AnonymousAudio]

Honestly, this seems like you hardcore angling (or shilling, if I were being more honest) that Martin Logan's poorly engineered speakers are somehow great technology. What they are doing isn't innovative or new in any way and will absolutely still have lobing in a critical frequency range. The other speakers in this line have nasty resonances, completely aside from the very non-linear frequency response.

I literally asked for another center thats in its price range and can compete. Lets say up to $2k. Prove me wrong i dont give a crap, i simply want the best i can possibly afford and right now it's the C100 from everything i've seen so far. Show me what you would choose for that budget...

 

[rynberg]

I have a SVS SB17 should be enough Bass. However having a Center that can play below 50hz is a plus. The only reason THX likes to use 80hz for home theater crossovers is because most cant handle anything close to full range. Do you think theaters crossover at 80hz on their Centers...i dont think so. So the closer i can get to full range within my budget I will go for.

Running a crossover lower than 80 Hz very rarely offers any benefits whatsoever, especially in a center channel. And especially in a small center channel with small woofers like the C100.

What does commercial cinema have anything to do with home use? You are trying to recommend running a puny 8" tall center speaker with (2) 6.5-inch woofers the same as a commercial cinema front speaker? BTW, the Dolby commercial spec is that the screen speakers are -3 dB at 80 Hz.