Properties of speakers that creates a large and precise soundstage

[ernestcarl]

I'll come back with more measurements in a separate thread, but here's a first on-axis measurement of the KEF Q350 in near field.

1/48 oct smoothing:
View attachment 326369

1/6 Oct smoothing:
View attachment 326370


Seems to correspond quite well with Stereophile's measurement:

KEF Q350 loudspeaker Measurements

Sidebar 3: Measurements

www.stereophile.com

Thanks. I would be interested to see more of your measurements of this speaker -- I just happened to have found a used unit locally selling at a significant discount. Can't say I'm going to buy it, but I am just a little tempted.

For sure, there is some semblance with JA's measurements... disturbance there would still be somewhat influenced by room acoustics and positioning/unit variance/design. Obviously, not all coaxial type speakers measure the same. My second-hand Fulcrum acoustic RX699 has a dip around 1.3 kHz which is mostly visible in the nearfield -- although, I'm not quite sure if this is truly reflective of all same new units coming out of factory.

Grill has been removed and port/edges sealed (personal choices -- so not at all the original intended application). EQ in use below is all my own using a miniDSP 2x4HD:

Some more "practical" in-room measurements:

**Hmmmn... I'm wondering now if the reason why I got it for cheap may be because there's an existing defect(?) in the xo network or transducer itself in this particular unit? There's nothing obvious in my other measurements and distortion around the xo looks fine. That's just the thing with used items... can't be 100% certain.

"uprocessed response" -- I'm assuming this is already with the passive network

I haven't yet measured the mid cone and HF compression driver individually without the passive xo network in place, but I might in the future.

Yeah, I really don't believe I should be so concerned that my bookshelf-sized coaxial speakers aren't "audiophile" perfect. The size is small and perfect for my own personal use case, and it sounds satisfyingly good enough -- to my cloth-ears, at least.

I know you have much "higher standards" than I do.

 

[sigbergaudio]

Since there are a number of Kef speakers with coax that have more or less picture perfect frequency responses, I'm not sure what we're trying to prove with in-room measurements of the Q350?

 

[HarmonicTHD]

Since there are a number of Kef speakers with coax that have more or less picture perfect frequency responses, I'm not sure what we're trying to prove with in-room measurements of the Q350?

Yep. Plus Armir already measured it with the Klippel. So what’s new?

 

[ernestcarl]

Yep. Plus Armir already measured it with the Klippel. So what’s new?

Apart from my own interest of Bjorn’s more detailed explanation/analysis… there are other coaxes in the wild that have yet to be reviewed or shown with any measurements. I’m sure most have flaws in one way or another.

Incidentally, I’m a little bit disappointed Erin didn’t at least listen to that one JBL coax speaker he recently measured.

JBL SCS 8 Speaker Review

JBL SCS 8 Speaker Review

www.erinsaudiocorner.com

Assuming it’s not so “hi-fi”, I’m curious if an EQ in the chain could make it so… acceptable enough to his own ears, anyway.

 

[HarmonicTHD]

Apart from my own interest of Bjorn’s more detailed explanation/analysis… there are other coaxes in the wild that have yet to be reviewed or shown with any measurements. I’m sure most have flaws in one way or another.

Incidentally, I’m a little bit disappointed Erin didn’t at least listen to that one JBL coax speaker he recently measured.

JBL SCS 8 Speaker Review

JBL SCS 8 Speaker Review

www.erinsaudiocorner.com

Assuming it’s not so “hi-fi”, I’m curious if an EQ in the chain could make it so… acceptable enough to his own ears, anyway.

All good.

The issue which I have is that by picking an old entry level coax and implying there are issues with all coax. It’s like me picking a budget non coax and claiming all non coax speakers are flawed. And we know both isn’t true.

As you pointed out there more coax speaker out there and yes one can only determine their merits once measured.

But there are plenty of non coaxes out there measured or not which also have (serious) flaws in their FR.

It is a matter of engineering and if well done, one can get very well performing coax speakers (KEF R, Ref, Blade and Genelec) but also very good non coax (also Genelec, Neumann, JBL etc).

 

[ernestcarl]

Back to the “soundstage” title of this thread, probably the best coax speaker(s) system is one that’s installed in an actual real stage venue:

Fulcrum Acoustic’s loudspeaker system selected for 'National Landmark' install

The New England Conservatory music school has recently completed the installation of a Fulcrum Acoustic loudspeaker array that features AH65 high-efficiency, full-range coaxial horns and RX699 coaxial loudspeakers. The sound system has been installed in Jordan Hall in the venue, which hosts a...

www.installation-international.com

https://www.fulcrum-acoustic.com/wp-content/uploads/2019/08/Prod-Spec-AH65-v7.pdf

 

[Bjorn]

Thanks. I would be interested to see more of your measurements of this speaker -- I just happened to have found a used unit locally selling at a significant discount. Can't say I'm going to buy it, but I am just a little tempted.

For sure, there is some semblance with JA's measurements... disturbance there would still be somewhat influenced by room acoustics and positioning/unit variance/design. Obviously, not all coaxial type speakers measure the same. My second-hand Fulcrum acoustic RX699 has a dip around 1.3 kHz which is mostly visible in the nearfield -- although, I'm not quite sure if this is truly reflective of all same new units coming out of factory.

Grill has been removed and port/edges sealed (personal choices -- so not at all the original intended application). EQ in use below is all my own using a miniDSP 2x4HD:

View attachment 326434

View attachment 326449


Some more "practical" in-room measurements:

View attachment 326435

**Hmmmn... I'm wondering now if the reason why I got it for cheap may be because there's an existing defect(?) in the xo network or transducer itself in this particular unit? There's nothing obvious in my other measurements and distortion around the xo looks fine. That's just the thing with used items... can't be 100% certain.

"uprocessed response" -- I'm assuming this is already with the passive network
View attachment 326494

I haven't yet measured the mid cone and HF compression driver individually without the passive xo network in place, but I might in the future.


View attachment 326436

Yeah, I really don't believe I should be so concerned that my bookshelf-sized coaxial speakers aren't "audiophile" perfect. The size is small and perfect for my own personal use case, and it sounds satisfyingly good enough -- to my cloth-ears, at least.

I know you have much "higher standards" than I do.

You would have to measure the drivers independently without the crossover as you mention besides together.

As said previosuly, most coaxial drivers wil both have a delay between the drivers that leads to a frequency deviation if it's not time aligned with DSP, and the two drivers will interfere with each other. The latter can lead to both dips and peaks. If it leads to peaks, the speaker will often sound harsh with some music since this happens in the presence area. I have seen this with some coax' and I couldn't get the speaker to sound smooth with various music material using transparent electronics.

KEF and Genelec have gone in opposite direction to solve the interference between the drivers. KEF is using dispersion, while Genelec uses a material in the woofer to absorb. Both seems to work, but that doesn't mean the audible result is the same.

 

[ernestcarl]

KEF and Genelec have gone in opposite direction to solve the interference between the drivers. KEF is using dispersion, while Genelec uses a material in the woofer to absorb. Both seems to work, but that doesn't mean the audible result is the same.

Isn’t it the other way around? Kef has the proprietary meta material absorber tech and Genelec uses the large slotted ports…

 

[Bjorn]

Isn’t it the other way around? Kef has the proprietary meta material absorber tech and Genelec uses the large slotted ports…

The meta material is to absorb sound inside the cabinet. I think the benefit of that compared to porous material is highly discussable

But here we're talking about the shape of the "star" around the tweeter and perhaps also those uneven patterns on the woofer and on the rim.

This disperses the sound in order to minimize the audible interference between the drivers.

The big question is how well does it work compared to a driver/speaker that doesn't have the intereference issue at all.

 

[ernestcarl]

The meta material is to absorb the inside the cabinet. I think the benefit of that compared to porous material is highly discussable

But here we're talking about the shape of the "star" around the tweeter and perhaps also those uneven patterns on the woofer and on the rim.

View attachment 326559

This disperses the sound in order to minimize the audible interference between the drivers.

The big question is how well does it work compared to a driver/speaker that doesn't have the intereference issue at all.

Doesn’t the vast majority of speakers (esp. in this small size category) have their own issues anyway? What would be the ideal alternative of similar size then be?

Still don’t know what Genelec’s woofer absorption tech is…

 

[Bjorn]

Doesn’t the vast majority of speakers (esp. in this small size category) have their own issues anyway? What would be the ideal alternative of similar size then be?

Still don’t know what Genelec’s woofer absorption tech is…

All speaker designs consist of compromises. It become a matter choosing the least ones.
But personally I've found other designs that I didn't work better than coaxials. With a complete lack of interference there's an openness, clarity and detail that's quite addictive.

 

[Pearljam5000]

Which is better sounding the coax driver on Blade One Meta or the coax on GENELEC Ones?

 

[thewas]

Isn’t it the other way around? Kef has the proprietary meta material absorber tech and Genelec uses the large slotted ports…

The KEF meta absorber is to absorbe the rear radiation of the tweeter and the Genelec slots to shape the radiation pattern of the woofers.

But here we're talking about the shape of the "star" around the tweeter and perhaps also those uneven patterns on the woofer and on the rim.

This disperses the sound in order to minimize the audible interference between the drivers.

That is not correct, the "star around the tweeter" (called tangerine waveguide) is to control (widen) the radiation of the tweeter on the upper end, the ribs on the midwoofer to reinforce it and this and increase its break up frequency and the surround on the rim (only in 2-way models, the 3-way has/needs only a tiny surround) to reduce the typical occurring eigenmode/standing wave. The interference is avoided by the smooth geometry avoiding edges and sudden changes in curvature.

The big question is how well does it work compared to a driver/speaker that doesn't have the intereference issue at all.

As above what is important is the avoidance of edges and sudden changes in curvature which is usually in comparison more an issue with classic designs where the tweeter "sees" the typical ridges of the close midwoofer surround so it cannot be said that other non coaxial loudspeakers don't have such issues at all.

 

[sigbergaudio]

Apart from my own interest of Bjorn’s more detailed explanation/analysis… there are other coaxes in the wild that have yet to be reviewed or shown with any measurements. I’m sure most have flaws in one way or another.

Why are you sure that they will, beyond likely not being 100% perfect, just as any other driver / driver design?

 

[Bjorn]

The KEF meta absorber is to absorbe the rear radiation of the tweeter and the Genelec slots to shape the radiation pattern of the woofers.


That is not correct, the "star around the tweeter" (called tangerine waveguide) is to control (widen) the radiation of the tweeter on the upper end, the ribs on the midwoofer to reinforce it and this and increase its break up frequency and the surround on the rim (only in 2-way models, the 3-way has/needs only a tiny surround) to reduce the typical occurring eigenmode/standing wave. The interference is avoided by the smooth geometry avoiding edges and sudden changes in curvature.


As above what is important is the avoidance of edges and sudden changes in curvature which is usually in comparison more an issue with classic designs where the tweeter "sees" the typical ridges of the close midwoofer surround so it cannot be said that other non coaxial loudspeakers don't have such issues at all.

I know it functions as a waveguide as well but I also thought it worked to minimize the interference between the drivers. If it's not, I stand corrected. However, if there interference is only related to the general geometry, I would think we would see a lot more coaxials with an improved frequency response.

Something I am observing with the KEF Q350 is a quite wiggly response above 2 kHz.

 

[thewas]

I know it functions as a waveguide as well but I also thought it worked to minimize the interference between the drivers. If it's not, I stand corrected. However, if there interference is only related to the general geometry, I would think we would see a lot more coaxials with an improved frequency response.

Something I am observing with the KEF Q350 is a quite wiggly response above 2 kHz.

How would some tiny ribs minimize the interference between the drivers? That is mainly done by the smooth geometric transition, (both the fixed Waveguide part around the tweeter and the mid cone surface) and the flat surround, so the tweeter doesn't radiate to edges or sudden curvature changes. Like written above several times the Q350 response has different reasons and that can be seen at the smooth anechoic directivity measurents.

 

[ernestcarl]

Why are you sure that they will, beyond likely not being 100% perfect, just as any other driver / driver design?

“Flaws” in my mind are just the same as “not being 100%” perfect. However, there are particular issues more prominent in certain coaxes — and, if it’s a horn loaded coax, some of these flaws get particularly exaggerated and may not be so easy to balance out/get right. The JBL PA speaker measured by Erin, for instance; I’m wondering if it could have been ever so slightly improved tonally if it just didn’t have that sharp hump around upper mid-range. Apart from the other irregularities in the FR, what areas most likely listeners would find the most audibly problematic? I’m sure it isn’t a total wreck just because of the rather ugly graphs… However, not having heard it myself I can only speculate.

 

[RipleyHRGiger]

I wish I could get my SVS Ultra Towers to have an even sound stage with off axis listening. From where I sit (just to the left of center) the phantom center from two channels is on point but from the right seat (this is theater seating with a small island in the middle so you can’t sit dead center) the right speaker is dominant and no matter how I point the speaker or how close or far from the wall it is it’s always dominate.

No my hearing is fine; both young and old listeners notice this as well.

My walls are treated but not overly so and I’m using dirac live which does help immensely to improve audio quality throughout the entire room; but that one right channel speaker (this happened with audyssey and it happens with direct stereo audio too), is always dominate and I can’t get a good phantom image from the right seating position

I’m wondering if maybe this is because I have my audio rack somewhat near the left channel speaker; it’s against the wall and about 3 feet in front of the left channel speaker.

I’ve tried toeing in at extreme angles too and still… still….

So, at this point I’m looking to buy some JBL horn style speakers or something with a wider stage in hopes that it’ll fix this. I love the SVS ultra towers, they have very good sound and blow my mind every time I listen to them with or without subwoofers and they play loud without any distortion (at least for as loud as I’m willing to listen hehehejeej)

But this sorta thing drives me insane and I need a solution.

I hope I’m not the only one who has been haunted by an audio issue like this before and that someone here can provide assistance or at least a hug and tell me it’s okay and that I’m not alone

Anyhow, thanks for reading and I hope everyone is having a nice week.

 

[sigbergaudio]

“Flaws” in my mind are just the same as “not being 100%” perfect. However, there are particular issues more prominent in certain coaxes — and, if it’s a horn loaded coax, some of these flaws get particularly exaggerated and may not be so easy to balance out/get right. The JBL PA speaker measured by Erin, for instance; I’m wondering if it could have been ever so slightly improved tonally if it just didn’t have that sharp hump around upper mid-range. Apart from the other irregularities in the FR, what areas most likely listeners would find the most audibly problematic? I’m sure it isn’t a total wreck just because of the rather ugly graphs… However, not having heard it myself I can only speculate.

So in summary it's speculation that coaxes is typically more problematic than non-coaxial designs?

 

[ernestcarl]

So in summary it's speculation that coaxes is typically more problematic than non-coaxial designs?

Well, no, I don’t think I would word it in such a manner.