I don’t believe anyone is stating they are ‘state of the art’, but a solid design that has obviously endured.
Keith
Keith
Subjective listening tests in the 1970s were afaik the first indication a lossy cabinet was one really effective way to reduce speaker colouration.So the subjective listening tests made by BBC sometimes in the 70's are considered as a proof of that design approach even now in 2020. This is a bit surprising, to me.
Regarding the Kef cabinet and driver design, I find this interview with Jack Oclee-Brown provides aditional valuable information to what has been discussed so far:
The ideal of a pulsating sphere goes back a long way. Peter Walker's Balls was one attempt, later resuscitated as the ring structure of the ESL63 where the loudspeaker was a section through a spherical wavefront.Interesting interview, but it was a bit hard to concentrate on because I honestly was more interested in the cat (who couldn't possibly have cared less about any of it). I'm guessing that the Ayre QX-5 is exactly the right level of "warm" when powered on but not in use - though I'm sure the view out the window helps.
Interesting (though not sure I 100% buy all of it) about the idea behind the tangerine guide.
The ideal of a pulsating sphere goes back a long way. Peter Walker's Balls was one attempt, later resuscitated as the ring structure of the ESL63 where the loudspeaker was a section through a spherical wavefront.
MBL do something similar, using a completely different method in their 'petal' loudspeakers in trying to create a pulsating sphere.
Whether a pulsating sphere (i,e omnidirectional) is the right approach for domestic stereo I'm sceptical about, but as a principle for a tweeter or even midrange, it makes a lot of sense.
S.
At this point we are so low in speaker data that I can't optimize the process that way. I need to get through measuring a bunch more so that we can see if our predictive scores are good.I would really appreciate if listening tests were done prior to reviewing measurements. I know this is the part that slows you down @amirm but perhaps you can grab a few speakers and knock-out their listening tests in a row whilst taking notes to include in their final review as the measurements become available?
The ideal of a pulsating sphere goes back a long way. Peter Walker's Balls was one attempt, later resuscitated as the ring structure of the ESL63 where the loudspeaker was a section through a spherical wavefront.
MBL do something similar, using a completely different method in their 'petal' loudspeakers in trying to create a pulsating sphere.
Whether a pulsating sphere (i,e omnidirectional) is the right approach for domestic stereo I'm sceptical about, but as a principle for a tweeter or even midrange, it makes a lot of sense.
S.
You can also do it with sound intensity measurement, special mic required. I have been involved with this sort of thing in industrial applications where you need to separate a particular machines noise output from that of the general noise in the area.How?
It can be calculated from surface vibration measurement, the engineer I know who designs speakers for OEM clients told me he does it this way.
How would a measurement microphone (or your ear) know which bit of the air pressure wibbling it was picking up was coming from the drive unit and which proportion was the spurious bit coming from the cabinet?
Maybe somebody has come up with a way of doing it but If so I haven't seen it published yet.
I can do some bump tests and post the resultsNowadays, one can use devices that measure acceleration on the sides and such of the cabinet.
It would be interesting to see the results of such measurements.
Neat takeaways for me:Regarding the Kef cabinet and driver design, I find this interview with Jack Oclee-Brown provides aditional valuable information to what has been discussed so far:
It is indeed the Reference 5, in one of the special "Foundry" finishes.Neat takeaways for me:
ls50 uses a floating brace that has dampening material between it and the outer wall.
the kef tweeter is a compression driver
Nobody seems to know that is an r11, not r5, behind them? (or is this some previous series?)
Changeable ports instead of port plugs.
Thanks for posting that!
Do you mean with an accelerometer? To put a accelerometer on the sides and measure the displacement of a cabinet wall?Nowadays, one can use devices that measure acceleration on the sides and such of the cabinet.
It would be interesting to see the results of such measurements.
Do you mean with an accelerometer? To put a accelerometer on the sides and measure the displacement of a cabinet wall?
Such an experiment has been done in this video.The experiment starts around 35 minute mark
Maybe @March Audio can tell if this actually worth full or not.