In the measurements of Hobby Hifi, this is a bit more clear (because of the relative/percentage scale)
It seems to be mostly 2nd order distortion from their measurements.
But a brought H3 across 100Hz - 900hz.
I stand to be corrected, apparently, there are some different measurements results.
See:
http://website.audiocomponents.nl/download/scan-speak/18WU-8741T00 - Hobby HiFi 2012-2.pdf
A SB Acoustics NBAC performs better there. (even compared to the 8ohm version)
When it comes down to 100Hz-2kHz.
The 4 ohm version really has some weird things going on?
http://website.audiocomponents.nl/download/scan-speak/18WU-4747T00 - Hobby HiFi 2010-4.pdf
Left is SB NBAC, right is SS 18WU both @ 90dB
Comparison from Hifi compass at roughly same SPL (not quiet)
But a brought H3 across 100Hz - 900hz.
I stand to be corrected, apparently, there are some different measurements results.
See:
http://website.audiocomponents.nl/download/scan-speak/18WU-8741T00 - Hobby HiFi 2012-2.pdf
A SB Acoustics NBAC performs better there. (even compared to the 8ohm version)
When it comes down to 100Hz-2kHz.
The 4 ohm version really has some weird things going on?
http://website.audiocomponents.nl/download/scan-speak/18WU-4747T00 - Hobby HiFi 2010-4.pdf
Left is SB NBAC, right is SS 18WU both @ 90dB
Comparison from Hifi compass at roughly same SPL (not quiet)
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Yes of course. Very transparent speaker with high resolution and pleasant timbre but quite different from Revelator series.
You can check my thread about IMD vs HD. I guess the story is similar for SB17 and 18WU.
https://www.diyaudio.com/community/...ormance-evaluation-an-imd-perspective.389247/
8V corresponds to 94dB, so it would be more correct to compare distortion plots at 5.6V
Extremely hard to say if they scale up well.
Also, you're testing full range as well as as low as 30Hz. It does not surprise me at all that the SB has trouble doing that.
The much lower xmax is already a very strong indication that this is never going to be a good match.
So zero surprises there for me.
But I think it's a very interesting candidate for a 2-way system from 100-150Hz and up. Much lower intermodulation issues there (because basically no cone excursion)
In an high-end system you want good performing multi subwoofers anyway.
BTW, measurements of Klang under Ton are not a good comparison.
They often contain errors, below 150Hz or so they have some weird in room artifacts and they often don't match up well with measurements from other people.
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Thanks, that matches my experience too.
I used 4ohm version as woofer in 3ways loudspeakers (+12MU/R3004/6020 and +12MU/T25B). It delivers bass and midrange quality at very high level, as usual for Scan Speak. I also used it as midrange (+28W revelator and 6600 in WG), very transparent and clear midrange, and thinking if it, the character was similar to 18WE.
While SB17 might be better midrange, it cannot compete as midwoofer in 2way or woofer in small 3way (I did both, + a lot of experiences with DIY and commercial speakers with SB17).
Ha! Really glad you're keeping safe & well, & even had chance to do this (and many thanks for doing so).
Here are the Klippel measurements from VoiceCoil Testbench;
https://www.scan-speak.dk/datasheet/reviews/15WU-4741T00_18WU-4741T00-VoiceCoil_2009-2.pdf
Also with the smaller 5 inch version.
As well as Erin's measurements;
https://www.erinsaudiocorner.com/driveunits/scanspeak18wu4741t00/
Both 4 ohm version.
Looking at the BL(x), Kms(x) and Le(x), it's pretty obvious the gain you will get when being used full range (aka below 100Hz).
Why the IMD is so much better (when being used full range!)
Pretty much in line with @racingpht
At a first glance, we kind of aspect that from the following tables:
SB Acoustics:
Scan Speak
3rd order harmonics are still dominant over the 2nd order for the 4ohm version, just like Hobby Hifi.
Which is kinda odd.
https://www.scan-speak.dk/datasheet/reviews/15WU-4741T00_18WU-4741T00-VoiceCoil_2009-2.pdf
Also with the smaller 5 inch version.
As well as Erin's measurements;
https://www.erinsaudiocorner.com/driveunits/scanspeak18wu4741t00/
Both 4 ohm version.
Looking at the BL(x), Kms(x) and Le(x), it's pretty obvious the gain you will get when being used full range (aka below 100Hz).
Why the IMD is so much better (when being used full range!)
Pretty much in line with @racingpht
At a first glance, we kind of aspect that from the following tables:
SB Acoustics:
Scan Speak
3rd order harmonics are still dominant over the 2nd order for the 4ohm version, just like Hobby Hifi.
Which is kinda odd.
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And when we look at IMD from 80Hz (not lower frequency or Fs), the picture looks all of a sudden very differently!!
Both at 89dB
source:
https://www.erinsaudiocorner.com/driveunits/scanspeak18wu4741t00/
https://www.erinsaudiocorner.com/driveunits/sbacoustics_sb17cac35-4/
(I extracted the gif image)
Both at 89dB
source:
https://www.erinsaudiocorner.com/driveunits/scanspeak18wu4741t00/
https://www.erinsaudiocorner.com/driveunits/sbacoustics_sb17cac35-4/
(I extracted the gif image)
I find the sound of 18we a bit warmer, lush and softer compared with 18wu, maybe because a bit stiffer cone and more odd harmonics of the 18wu woofer.
I don't like aluminum SB speakers in the midrange at all no matter how low their distortion are
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Regarding SB17 as a midrange, it was my assumption based on the measurements and assumption that when it is relieved from woofer duty, the midrange could sound ok. Anyway, I will not try it, it is not worth it.I find the sound of 18we a bit warmer, lush and softer compared with 18wu, maybe because a bit stiffer cone and more odd harmonics of the 18wu woofer.
I don't like aluminum SB speakers in the midrange at all no matter how low their distortion are
Purifi tech note actually has a good explanation on this:
https://purifi-audio.com/blog/tech-notes-1/distortion-the-sound-that-dare-not-speak-its-name-8
"Hysteresis distortion is worst in underhung drivers because of the sheer volume of iron surrounding the voice coil."
Similarly, ATC SLMM white paper has talked about the current distortion effect (for their underhung drivers)
http://atc.audio/wp-content/uploads/2014/10/ATC-CORP-BROCHURE-FINAL-10.pdf
In the case of 18WU, dual copper sleeve greatly reduced hysteresis distortion in mid-high frequencies, but it's still higher than similar overhung voice coil with copper sleeve. Plus, shorting ring is less effective in lower frequencies. But you do get the benefit of lower 2nd order distortion and IMD compared to many other copper sleeve drivers, probably due to less force factor modulation.
Also wonder how its paper cone sounds VS the NE149W-08 from Peereless which has a cone material nearer from SB Acoustic but hybrid paper/Ti voice coil ?
Different sizes not quite correct to compare one with another but I can compare NE180W which is much close in the cone Sd to 18WU. Both speakers are excellent but if my memory serves me, 18WU has a richer timbre and a bit spacious, more deep sound. Nevertheless, I would have a hard time in choosing a one of both speakers