Will be interesting point, i am preparing a wwmt with the alu cones, ptt8 , ptt4 , and for tweeter i hope the purifi will be here very soon.
Perhaps we should start a discussion as to why the fibre cone is better as perceived by our hearing. Could be some micro resonances or standing waves in the cones, who knows. The accuton midranges i still use today are not free either, but overall the best i could find then.
I am finalising the shape design of baffle(controlling diffraction hump and dip), sims look ok, now the measurements as proof. 3d printer (a fast one) for baffle just arrived.
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Isn't this why Linkwitz started to modify his WM61 capsules well over 40 years ago?
Great question.
AFAIK the late SL didn't document the performance improvement after modifications, but he did write:
"The output voltage from the modified WM-60AY capsule can swing 5 Vpp (!) max at 141 dB SPL using a -9 V supply, and easily overload a preamplifier with too much gain. The microphone noise floor measures about 36 dB SPL, 80 Hz to 20 kHz, with a 1/f corner of around 100 Hz... With a sensitivity of 8 mV/Pa (= 94 dB SPL) this translates to 10 uV of noise, or 71 nV/sqrt(Hz) noise voltage density. A-weighted noise is estimated as 30 dB(A)"
Reference:
https://www.linkwitzlab.com/sys_test.htm
I wouldn't call that a microphone suitable for making low harmonic distortion measurements...
The Sonarworks microphone is advertised a
“An omnidirectional measurement microphone with an individual calibration profile. Every microphone has been measured by Sonarworks acousticians against an ANSI-certified measurement microphone. This means perfect accuracy within the audible range and freedom from sample-to-sample irregularities”
As far as I can tell, it meets its spec as a measurement microphone.
What users (like me) shouldn’t be doing is measuring harmonic distortion with it…
Measuring distortion isn’t easy…
AFAIK the late SL didn't document the performance improvement after modifications, but he did write:
"The output voltage from the modified WM-60AY capsule can swing 5 Vpp (!) max at 141 dB SPL using a -9 V supply, and easily overload a preamplifier with too much gain. The microphone noise floor measures about 36 dB SPL, 80 Hz to 20 kHz, with a 1/f corner of around 100 Hz... With a sensitivity of 8 mV/Pa (= 94 dB SPL) this translates to 10 uV of noise, or 71 nV/sqrt(Hz) noise voltage density. A-weighted noise is estimated as 30 dB(A)"
Reference:
https://www.linkwitzlab.com/sys_test.htm
I wouldn't call that a microphone suitable for making low harmonic distortion measurements...
The Sonarworks microphone is advertised a
“An omnidirectional measurement microphone with an individual calibration profile. Every microphone has been measured by Sonarworks acousticians against an ANSI-certified measurement microphone. This means perfect accuracy within the audible range and freedom from sample-to-sample irregularities”
As far as I can tell, it meets its spec as a measurement microphone.
What users (like me) shouldn’t be doing is measuring harmonic distortion with it…
Measuring distortion isn’t easy…
That was not my point: those mics were never intended to do so. But their overload characteristics dramatically improved i.m.o.
Maybe I should elabotate: to my best of knowledge all these cottage industry "calibrated" ECM manufacturers buy very large quantities of these capsules for virtually nothing in China. Then the selection process begins: from, say, 5000 pcs maybe a hundred are selected, the rest is dumped through the Mousers, Conrads and Pollins of this world. The 100 chosen are put in fancy housings and sold at a premium with a calibration file. The chosen are not subject to the SL mod.
But selecting and calibrating etc. does not change the fundamental shortscomings of this type of mic, that was never designed to be a measuring device.
But selecting and calibrating etc. does not change the fundamental shortscomings of this type of mic, that was never designed to be a measuring device.
That is an incomplete conclusion and shall not and cannot be used a an absolute definitive answer without context.
In fact, in my opinion it's not even a correct conclusion as an absolute statement.
Electret condenser microphones have their limits and threshold, like literally anything else!
As long as you respect those limits, or know how to look around them, they still have their usage.
Maybe not for the sport called pixel peeping, but it WILL show you when the distortion of a tweeter starts to ramp up or where certain distortion modes are from like cone break-ups.
So saying that electret microphones are not suitable for measuring distortion, is just simply incorrect.
Shown by already those two arguments.
Which is what's needed for 99% of loudspeaker designs.
It's only a very small and select group of people that really care about those very low numbers.
If we wanna actually stick to real science and engineering, we MUST also ask the question if those numbers are not totally swallowed up by things like background noise etc?
Knowing relevance, significance and orders of magnitude is an absolute essential part with any experiment.
Giving any conclusions without providing those is by definition already extremely debatable and in some cases completely false.
It's important to give the entire context to a certain statement and/or conclusion.
But to ask you a very fair question, what would you expect from very affordable gear?
And often also not needed.
Especially when information can be gathered from other people and/or companies.
Or do you expect that the same driver would magically perform totally different in a new system?
Let me ask another question.
What additional information do you expect to gather that is useful for designing a loudspeaker system, besides the information that is already available, can be cross-correlated, verified and being considered as a (semi) industry standard?