Maybe of some use.......notice both have curvilinear flex.
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Yes indeed exactly.
As mentioned the issue is usually imagined. People seem to also feel offended or insulted when others try to tell them their imagination is false.
When all we are doing is assuring them to not worry about it and move on.
If it was true then multi way speakers wouldn't even work. Rather the tweeter mounted directly centered, or directly next to a woofer.
The woofer would also cause doppler issues, because a few mm of spacing does nothing to the story.
It does change the phase relation of course, which is why a coaxial can be so useful.
AFAICT, the whole premise of Doppler distortion w.r.t. speakers relies on changing directivity vs frequency. Essentially, a low frequency, X, modulates the path length through the air of a higher frequency, Y, because some of the air volume 'spills' sideways with X being more omni-directional than Y.
The above applies with a single driver operating as a perfect piston where its only flaw is the finite size, bigger than a point source and smaller than a continuous wall. With coaxial tweeters, it seems like there would a slight re-arrangement of some of the conditions, but not necessarily fixing anything. Funnelling the tweeter sound through a hole in the woofer magnet seems to open up new issues like amplitude modulation from changing horn geometry.
My experience has been it doesn’t matter……there’s still a slight screen door effect going on over the interface. Right up close, it’s not noticeable….but step back and the transparency is lacking. Personally I use them for monitoring for the past 3 years…..in the near field. They’re a great choice for some aspects of a mix………but clinicians they are not.
Think Fs/ Qms is 3.75, even if its a minor
And it´s 16 inch Fs 24 VAS 649
JBL 2215 (A,B, H) Fs/ Qms is 3.63
And is a 15 inch Fs 20 VAS 736 and with higher power ratings
Interesting. Then what is better?
I have a 26ADC in a waveguide with Satori MW13TX, which sound great, even though I do like the way the KEF coax let you move around, and not screw up the stereo image, like a typical midrange/tweeter combo easily does.
But maybe if I crossed a Satori 9" with a big waveguide.... around 1000Hz 🤔
At one point i read a couple of text books on human hearing. Near vthe ehnd of one, the author dismissed such doppler as mosstly irreevant I have not given it any concern since.
dave
Compromises.........how often do you really move around while listening for enjoyment that the stereo image needs to be maintained?......if the SB 2way gives you better overall clarity and can certainly handle more power with lower distortion?.....i know which compromise i'd make. The coax works in a nearfield triangle and i'm not moving......that works for me in the nearfield......but that's work and there's better solutions for play time IMO.
The Satori 9.5" woofer doesn't exhibit significant beaming until 2k...........a 1.5k 2nd order filter would not only be fine....it would be better than 1k for both power handling and directivity
Then you're either not listening or writing off the lack of high frequency detail as 'warm' or some other audiophile descriptor. The fuzziness is real. throughout the crossover region and beyond.
Well difficult to be sure it's doppler distortion but non high passed and at high volume my small Tannoy ( 8") generate a weird wobbly kind of distortion.
I didn't experiment this artefact with my more 'regular design' loudspeakers.
I have not tryed with my Kef drivers as they seems much more fragile to me, and i never really experienced it with P.A. drivers though ( it probably happens too but at such high level i could not withstand spl. The fact they usually doesn't go really low might help in mitigating the effect for them too?).
I didn't experiment this artefact with my more 'regular design' loudspeakers.
I have not tryed with my Kef drivers as they seems much more fragile to me, and i never really experienced it with P.A. drivers though ( it probably happens too but at such high level i could not withstand spl. The fact they usually doesn't go really low might help in mitigating the effect for them too?).
There's a link earlier in this thread (post 192) to another from 2015. In that one, Andrew Jones makes the comment that doppler shift is not a concern, as does planet10's reference to an older text. So that is to say that the speed of the cone doesn't really matter.
But Jones did say the cone movement matters. As does Erin's measurements. Basically the cone moving is the same thing as you moving a driver's position in the wave guide throat. The result is a change in frequency response. The dip around 8khz in the Q100 measurement posted earlier is a good example.
Which is why you don't hear it when high passed. The cone doesn't move very far. It's not a cone speed thing (so not doppler), it's a cone excursion thing.
There's also cavity resonance (space between the tweeter and former, and cavity under the tweeter) and the non-moving part around the tweeter that matter.
Which is so say, it can be designed around. If it was doppler, there would be no avoiding it.
But Jones did say the cone movement matters. As does Erin's measurements. Basically the cone moving is the same thing as you moving a driver's position in the wave guide throat. The result is a change in frequency response. The dip around 8khz in the Q100 measurement posted earlier is a good example.
Which is why you don't hear it when high passed. The cone doesn't move very far. It's not a cone speed thing (so not doppler), it's a cone excursion thing.
There's also cavity resonance (space between the tweeter and former, and cavity under the tweeter) and the non-moving part around the tweeter that matter.
Which is so say, it can be designed around. If it was doppler, there would be no avoiding it.
Sure it can be minimised, Kef did a bunch of effort in their driver design to do so..
In case it wasn't evident from my previous answer i'm not convinced about doppler issues with loudspeakers.
That said the issue described in previous post i ( an other it seems) experienced is real and can compromise outcome for sure.
Not all drivers are plagued... or let's say at different level of severity.
It could explain too why some people prefer to make an other set of compromise ( lower xover point on woofer rather than past 250hz hp) on some design using P.A. originating loudspeakers ( i think about Airvoid and it's Bms based loudspeakers).
In case it wasn't evident from my previous answer i'm not convinced about doppler issues with loudspeakers.
That said the issue described in previous post i ( an other it seems) experienced is real and can compromise outcome for sure.
Not all drivers are plagued... or let's say at different level of severity.
It could explain too why some people prefer to make an other set of compromise ( lower xover point on woofer rather than past 250hz hp) on some design using P.A. originating loudspeakers ( i think about Airvoid and it's Bms based loudspeakers).
Given the apparent amount of interest and debate, why not perform a simple experiment? If the coax can be biwired (or jumper-shorted across +/- with small R), stack a pair sideways and play one coax tweeter-only, the other coax woofer-only (in mono). Compare with stock. Two pairs could do stereo, or mono side-by-side for direct comparison. Etc.
I'm sure the pioneers had done such tests to arrive at their conclusions.
I'm sure the pioneers had done such tests to arrive at their conclusions.
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Already done ( i'm dsp/multiamp user, and 90% of coax i used/played with were using this). It didn't revealed anything to me except the 'issue' i was talking about is definitively related to both section playing together. But about the nature of the issue... nothing definitive.
About the 'missing clarity' well... how many have done non sighted test?
About the 'missing clarity' well... how many have done non sighted test?
Perhaps you can eliminate some of the distortion theories AM/FM/phase/moving-horn? Wide off-axis measurement differences should help some. (Edit: using a reflector for very high frequency.)
(I think for peace of mind as well as more bass we invariably go 3-way for smaller coaxes anyway. Mine: Tannoy P8/matching woof; LS50meta/woof; multiple 15" reflector far-field TBD.)
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On the face of it they are not the same thing -- a moving tweeter changed the distance to mic.
In the context of changing the frequency response of a waveguide/horn, the two are the same. As far as a "measuring technique" induced error, at a normal seating position (and hence audible by a listener) I doubt it.
All the micro speculation seems like skipping over the giant and already measured and data posted showing the impact of moving the cone to either extent of excursion.
All the micro speculation seems like skipping over the giant and already measured and data posted showing the impact of moving the cone to either extent of excursion.