Here you go, ASR website Blog:
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Crap, I can no longer claim Iâve never read a post on that site now, dangit
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Very interesting given those listening to the speakers are immensely familiar with them and the measured suck out looks horrible.
Ours is a complex, confounding hobby.
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Hi @Paul there are 2 big holes in the freq response.
Your explanation does explain the one at the higher end of the freq response (tweeter)
But I canât see how that explains the biggest hole 1kHz to 5kHz ?
(Copyrighted material removed)
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You obviously have not seen this graph that Chris posted on the forumâŚThere is not a problem with frequency response
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Paul confirmed and it led his diagnosis and presumed fix
Final word not yet in
What new information do you have to make this claim?
Yup, it is not a site Iâd typically seek out. Curiosity got the best of me.
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none, I suspect speaker improvement is not yet dead ended
Maybe Paul should contact HFN with this so they could write a addendum in a future issue.
Iâll post some of our measurements tomorrow (I left one of my measurement laptops at home).
As Paul mentioned, the dips you see in the response are because of a broken/malfunctioning tweeter (where the diaphragm is pinned against the magnets from air shipping). Again, we found the cause and fix and this affected a rather small number of units and can be corrected by placing a small pinhole in the rear chamber of the tweeter (or simply replacing the tweeter).
I did some Klippel NFS testing on a previous prototype but the NFS system has some significant errors at lower frequency (though that issue hadnât been acknowledged by the lab). I understand that Andrew Jones and Laurie Fincham (who used to head the AES committee on loudspeaker measurement standards for many years) may be doing an AES paper comparing various measured results versus the Klippel NFS. I still think itâs a cool tool and want one but it left me scratching my head versus careful ground plane and close mic / summed measurements below a couple hundred Hz.
HiFiNewsâ response below 1 kHz is correct and unaffected by the tweeter issue.
Here is a gated measurement of an aspen FR20 at 0, 10, 20, 30 degrees horizontally.
Here is a contour plot of the horizontal directivity and a directivity index measurement showing that things are pretty smooth and constant through the mid-treble crossover region (without a narrowing in the midrange and flare at the bottom end of the tweeter.
Directivity index and ERDI
Bass Extension (2 pi ground plane measurement)
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Yes, they have been made aware but it will probably be a number of months before this can happen.
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Luscious measurements
This kind of dip is not unusual by the ânearfieldâ measurement.
HFN didnât specify (or did I miss it?) how they setup the microphone (distance and height relative to tweeter/midrange).
We can find tons of examples (dip in frequency response) in published measurements done by the reviewer of all kinds of speakers.
FR20 and many other speakers are not designed to listen straight at your face from a few feet distance.
One example, Thiel CS3.6, measured by Stereophile in 1993.
Measurement distance is 45" (3.75â)
@stac: Please see/read Chrisâs post about 3 posts above.
FYI.
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What I do know is I am thoroughly enjoying my FR20âs, and fortunate to be able to own a pair.
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Iâve no question over how good the FR20 are, not heard them yet, but what on earth we HFN up to? Are they deaf? Are they biased? Did they call PSA about the results? Did PSA get an advance copy of the review?
How could they possibly believe or accept that a speaker would be designed to perform like that?
Thanks to Chris for his charts !!!
Yes! Go, Chris!
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the cauldron of psycho-acoustics
always consider who is biased and why
both positive and negative views can be biased
in clinical research, we have ways to mitigate bias, but these procedures have rarely been used elsewhere