Why are coaxials so rare?

[stevenswall]

I have built plenty of 2-ways with discrete drivers that play louder and cleaner, image superbly, and provide excellent frequency response down to at least the same point - and also need subwoofers to plumb the depths. Coaxials are IMO just an over-hyped technology that costs more to get decent performance from - and I don't see that price point dropping. Others are in fact jumping on the same over-hyped train because they can sell coaxial speakers for a higher price, not because they are looking to compete with a lower price point product. It's just more snake oil to shake more money out of gullible buyers hearing false advertising copy about better imaging, coherence, etc. As I have said before, coaxials don't do anything better than discrete driver loudspeakers. As I have also said, good 2-ways free you up of the need for a crossover in the most critical 150 Hertz to 800 Hertz region, and they can be built easier and cheaper than coaxials...

Coaxial do better vertical dispersion, so ceiling and floor reflections, which you don't care about... The soundstage is literally more coherent and stable over an additional plane.

The crossover argument is not valid... Well made active crossovers are transparent, as measurements have shown on various Genelec models.

Yep. Non coaxial are cheaper. So are one way speaker. So are passives vs active... And so on and so forth. Not the argument anyone is making.

 

[thewas]

Which drawbacks the Genelec Ones has?

Just exemplary the joint used to fix the mid membrane to the tweeter instead of a spider reduces relatively high lower frequency limit of the mid driver and increases non linearities at larger travel. Everything in this world is a compromise.

 

[voodooless]

Probably I shouldn't have mentioned that I happen to own a pair of KEF Uni-Q coaxials for comparison purposes because they are frankly nothing special. They are just a coaxial 2-way loudspeaker that I have carefully compared to numerous other 2-way loudspeakers using discrete drivers that all totally outperformed those KEFs when it came to EVERYTHING

Objectively?

BTW, what makes you think your KEF R7 is a perfect point source when only two of the four drivers are coaxial and the other two drivers are located elsewhere on the front panel of the loudspeaker? In actual fact both of those separately located bass drivers, are handling the same exact vocals and cello up through 400 Hertz simultaneously from two separate locations on the front baffle, neither being coincident in location with the driver handling all of the music over 400 Hertz.

That is not completely accurate. It's not a "perfect" point source, but for the frequencies they play, they do act as a point source, because they are close enough to each other to not cause any lobing. The sound nicely sums together to give a coherent wavefront coming from the centre of the two sources. This will however restrict vertical directivity, but usually, that is exactly the point.

Do you have any examples of 2-way speakers that have as good directivity as the good coaxial designs measured here?

That would defy the laws of physics I guess an MTM could come quite close.

In the end, the question is: how much does it really matter? Since everything is always a compromise, you can make different compromised in different circumstances. Your room, where you sit or move in it will mostly dictate what compromises are the smart ones. There is never a single solution that works best.

 

[abdo123]

In the end, the question is: how much does it really matter? Since everything is always a compromise, you can make different compromised in different circumstances. Your room, where you sit or move in it will mostly dictate what compromises are the smart ones. There is never a single solution that works best.

I don't think that's really a valid response since coaxials are better than 2-way speakers in every single way. there is no compromise here.

even 3-way coaxials are better than regular 3-ways, it's only above that in terms of headroom where coaxials might have drawbacks.

 

[voodooless]

I don't think that's really a valid response since coaxials are better than 2-way speakers in every single way. there is no compromise here.

even 3-way coaxials are better than regular 3-ways, it's only above that in terms of headroom where coaxials might have drawbacks.

There is always a compromise! For the same size, the coax will have less surface area for instance, and there is the matter of IMD, that for a small 2-way, might be an issue due to high excursion. And then there is the added complexity, ragged on-axis response, the fact that a coax usually does not give a fully tight seal, etc.

None of this means it can't make a fantastic speaker though.

 

[xaviescacs]

I think that from an strategic point of view, go for the coaxial design is quite a commitment. It may be better if done properly, but you loose design flexibility, and that makes a tough decision to make as a company.

 

[tecnogadget]

I have built plenty of 2-ways with discrete drivers that play louder and cleaner, image superbly, and provide excellent frequency response down to at least the same point - and also need subwoofers to plumb the depths. Coaxials are IMO just an over-hyped technology that costs more to get decent performance from - and I don't see that price point dropping. Others are in fact jumping on the same over-hyped train because they can sell coaxial speakers for a higher price, not because they are looking to compete with a lower price point product. It's just more snake oil to shake more money out of gullible buyers hearing false advertising copy about better imaging, coherence, etc. As I have said before, coaxials don't do anything better than discrete driver loudspeakers. As I have also said, good 2-ways free you up of the need for a crossover in the most critical 150 Hertz to 800 Hertz region, and they can be built easier and cheaper than coaxials...

This is like the (I just lost count) post in a row where you only tell us your personal/subjective opinion on coaxials. We get you mate, you are not very fond for them, but you haven't enlighten us yet nor provided any actual data to back up your claims, with the exception of your (very personal) "150Hz to 800Hz crossover rule". ¿Is it really 150Hz to 800Hz region the most critical? ¿Who says so? ¿Has it been proven?¿Why that region and not 1kHz to 3kHz, just to put a different example?.

I also don't get why you steered all your claims based on only small 2-ways Uni-Q config. ¿Are those old or contemporary speakers? ¿Why not specify models? OP enquiry about coaxial technology regardless of configuration.

The same is true for your recommended 2 way discrete drivers...no model, no data performance, no nothing, just your thoughts...and not really sure what you mean with discrete drivers clasification...coaxials are also discrete drivers, a midrange and a tweeter, but sharing a concentric configuration over the coil axis.

Coaxials being "extremely power limited" ?????? Unless we are talking about an active design, I haven't seen any power limitations on all the passive coaxials tested by Amir and Erin. In fact Erin thoroughly measured different isolated Uni-Q drivers several years ago, prior to start testing speakers with Klippel NFS, and the results doesn't show any pinch of power compression. At the end of the day the midrange will behave like any non coax driver, it has its own motor magnet and not affected by all by the tweeter in that regard.

Vertical directivity isn't actually all that critical when you're seated in the hot seat listening to two speaker stereo music, unless you suddenly get up from your seat to stand up. There are quite more than "a few examples" of loudspeakers with discrete drivers that deliver pinpoint imaging. I for one have owned many, including ones I have designed and built.

Except there is little evidence that time alignment and perfect step response is even critical. Our auditory system only processes timing information over a narrow frequency window, primarily 200Hz - 1Khz, rapidly declining after that. That is likely why time alignment and step response has not correlated well to listener preference.

We should first clarify that there isn't a real consensus or definition among most listeners and members about things like "pinpoint imaging", "soundstage", etc. It is quite a subjective terminology, and much harder to quantify like tonal balance for example.
In the absence of such a consensus or standardization, I refrain from data that could provide an answer to this difference whereby many users feel they get "pinpoint imaging" with coaxial. Therefore, the fact that the drivers have the same acoustic center, are aligned in time, and have a better step response, as well as excellent directivity, is one of the few data we have that can explain the difference with other topologies.

Now what I don't understand is why leave aside the vertical directivity? It is true that 95% of the time my listening sessions are sitting on LP, but when I get up and walk around the room, it is incredible how the response is not modified, and this is a simple demonstration of the pedigree of this typology. Back to the objective, a good vertical directivity will cause better interaction of the reflections with the floor and ceiling, a better Total Early Reflections response, therefore a better response in general, all this also affects when you are sitting on the "hot seat"...

It makes no sense at all to limit yourself to prioritize only the horizontal plane. Under that same logic, I could say that multichannel reproduction is not so critical, stereo is not so critical either, let's listen in mono, and in fact, it is not even critical to use several drivers, so a single full-range cone is enough, why worry about the cabinet if a cube box does the job, you know what? A single Auratone 5C in mono is enough for everyone (irony).

 

[audio2design]

Now what I don't understand is why leave aside the vertical directivity? It is true that 95% of the time my listening sessions are sitting on LP, but when I get up and walk around the room, it is incredible how the response is not modified, and this is a simple demonstration of the pedigree of this typology. Back to the objective, a good vertical directivity will cause better interaction of the reflections with the floor and ceiling, a better Total Early Reflections response, therefore a better response in general, all this also affects when you are sitting on the "hot seat"...

It makes no sense at all to limit yourself to prioritize only the horizontal plane. Under that same logic, I could say that multichannel reproduction is not so critical, stereo is not so critical either, let's listen in mono, and in fact, it is not even critical to use several drivers, so a single full-range cone is enough, why worry about the cabinet if a cube box does the job, you know what? A single Auratone 5C in mono is enough for everyone (irony).

Most good listening rooms tend to significantly reduce floor and ceiling reflections. Line arrays also reduce floor and ceiling interaction. Depends whether you want to listen to the recording or the room?

 

[q3cpma]

ragged on-axis response

Not inherent.

the fact that a coax usually does not give a fully tight seal

I don't understand what this means.

Honestly, a coaxial has very few inherent drawbacks when used in domestic or nearfield/midfield studio situations (not PA or main monitors) and in a n-way design with n >= 3. Not having OEMs as good as KEF/Genelec is probably the main reason for lack of adoption; that and BOM increase that won't please the bean counters that are today's executives.

 

[voodooless]

Not inherent.

Are you sure? There are next to none that don’t have a ragged on-axis response.

I don't understand what this means.

Normally the dust cap closes of the voice coil and makes a airtight seal. Removing it and adding a tweeter makes airflow possible between tweeter and woofer voice coil, and therefore is not airtight. Some special design seem to add a surround in the inside as well, but it rarely seen. Woofers with phase plugs can have the same “issue”, but they seem to have fallen out of grace nowadays. Now is this a major issue? Probably not in most cases.

Honestly, a coaxial has very few inherent drawbacks when used in domestic or nearfield/midfield studio situations (not PA or main monitors) and in a n-way design with n >= 3.

Absolutely!

Not having OEMs as good as KEF/Genelec is probably the main reason for lack of adoption; that and BOM increase that won't please the bean counters that are today's executives.

Genelec generally does not use their own drivers, but have them made by Peerless and Seas. The units in The Ones seem to be something special though. They are no derivatives of existing OEM units that I know of. That probably explains the additional price. A lot of extra R&D went into these units.

 

[BrokenEnglishGuy]

I don't think that's really a valid response since coaxials are better than 2-way speakers in every single way. there is no compromise here.

even 3-way coaxials are better than regular 3-ways, it's only above that in terms of headroom where coaxials might have drawbacks.

My favorite design is a 3-way coaxial, the driver are pretty close enough to me, the design that i don't like is the typical 2 way with a big woofer..

 

[q3cpma]

Are you sure? There are next to none that don’t have a ragged on-axis response.

What's ragged with the Ones? The raggedness generally stems from diffraction, so you "just" have to fight it with the usual methods.

Normally the dust cap closes of the voice coil and makes a airtight seal. Removing it and adding a tweeter makes airflow possible between tweeter and woofer voice coil, and therefore is not airtight. Some special design seem to add a surround in the inside as well, but it rarely seen. Woofers with phase plugs can have the same “issue”, but they seem to have fallen out of grace nowadays. Now is this a major issue? Probably not in most cases.

I see.

Genelec generally does not use their own drivers, but have them made by Peerless and Seas. The units in The Ones seem to be something special though. They are no derivatives of existing OEM units that I know of. That probably explains the additional price. A lot of extra R&D went into these units.

Yes, thanks for elaborating.

 

[voodooless]

What's ragged with the Ones? The raggedness generally stems from diffraction, so you "just" have to fight it with the usual methods.

Those are 3-ways. We were mostly talking about 2-ways. In a 2-way there is almost no way to get rid of the surround because you need the excursion. In a 3-way that works better due to the higher x-over frequency.

But yes, The Ones do exceptionally well in this regard.

 

[q3cpma]

We were mostly talking about 2-ways.

My bad, I didn't get that.

 

[Tonygeno]

The biggest issue with the Genelec 8361B is that the lower frequency distortion increases substantially at only 98 dBA per Amir's review. That means they do not handle as much power, nor play as loud and clean without distortion as some other speakers using discrete drivers. The people going "gaga" over the almost century old technology of coaxial drivers are people just like you that read advertising copy about "perfect point source" drivers and perfect imaging, but who are in fact inexperienced at loudspeaker design and just parrot such advertising copy. BTW, what makes you think your KEF R7 is a perfect point source when only two of the four drivers are coaxial and the other two drivers are located elsewhere on the front panel of the loudspeaker? In actual fact both of those separately located bass drivers, are handling the same exact vocals and cello up through 400 Hertz simultaneously from two separate locations on the front baffle, neither being coincident in location with the driver handling all of the music over 400 Hertz

Since there is no 8361B, I assume you are mistaken. Or did he measure the 8361A?

 

[tecnogadget]

In a 2-way there is almost no way to get rid of the surround because you need the excursion.

Thanks for that info. I always wondered why KEF kept the same surround on the subsequent LS50 active and passive generations instead of the Z-Flex surround on R and Reference series.
I thought it was mostly a marketing driven decision to differentiate between products lines.
Once I read your reply, it all made sense.
In fact I feel embarrassed as not having realized before haha.

 

[q3cpma]

Thanks for that info. I always wondered why KEF kept the same surround on the subsequent LS50 active and passive generations instead of the Z-Flex surround on R and Reference series.
I thought it was mostly a marketing driven decision to differentiate between products lines.
Once I read your reply, it all made sense.
In fact I feel embarrassed as not having realized before haha.

Unless I'm mistaken, "Z-flex" designates the ribbed surround on the LS50 (https://www.mx.kef.com/blog/the-z-f...-part-of-the-uni-q-s-unparalleled-performance).

 

[BrokenEnglishGuy]

id like to see KEF starting to use the P-flex from the KC62..

 

[stevenswall]

Your room, where you sit or move in it will mostly dictate what compromises are the smart ones. There is never a single solution that works best.

If we're going by performance and not price in a "typical living room" what is the compromise when it comes to coaxial speakers?

Cars no longer using a carburetor isn't a compromise. LED lights aren't a compromise. High efficiency amps aren't a compromise.

They simply work better in virtually all regular use cases.

I think it's the same with speakers: Having a team of engineers make an active version of a speaker isn't going to degrade it. Using an excellent coaxial driver instead of multiple drivers isn't going to degrade performance, but will increase it along the vertical axis. Engineering a port that isn't just a short, straight tube, one that actually pays attention to turbulence and tuning is going to increase the performance of any ported speaker it's applied to, without drawbacks besides price being higher due to the complexity.

Where is the performance compromise?

 

[thewas]

Cars no longer using a carburetor isn't a compromise. LED lights aren't a compromise. High efficiency amps aren't a compromise.

They simply work better in virtually all regular use cases.

Broken down high tech digital injection car in the end of nowhere can be a big problem thus also compromise. LED spectrum is often a compromise compared to a incandescent light bulb. Class D amps can have higher IMD distortions and more impedance related FR variation.

Some things can work better in more usual situations but in the end not in all, everything is a compromise and people have different needs. Same a common good coaxial driver cannot for example offer wide horizontal and narrow vertical directivity which can be advantage in some situations and for example one of the reasons Genelec offers the S360.