Joe Rasmussen said:
Looks like they've used it to form a funky looking rear chamber, no doubt to help with the rear wave. They use the same shape on the cones. The benefit of the rear chamber shaping is of merit but maybe the shape is just a marketing thing used to identify the tweeters with the cones?
nicoch46 said:
Huh??
W18EX001: Gap height =6mm. Coil height= 16mm linear Xmax=5mm
W18NX001: Gap height= 6mm. Coil height= 20mm linear Xmax=7mm
Coil travel and Xmax are not the same.
tinitus said:
If they're using symmetric drive (SD) then that will no doubt help things. Its claimed it offer linear rise time regardless of VC position in the gap.
Do Scanspeak own the patent for that or is it Audiotechnology? I notice both use it.
nicoch46 said:
I know that the owner of Audiotechnology created Scanspeak but I was wondering who owned the patent on SD. Maybe its Skaaning himself?
jmsent said:
Yes, we need to distinguish between Xmax and Xmech as well as Peak and Peak to Peak.
Example: Seas W18EX001 5mm (10mm P-P) Xmax and 9.5mm (19mm P-P) Xmech
Otherwise It’s like comparing pears and apples.
ShinOBIWAN said:
They just use different designed farradays to overcome the patent, but I believe that patent is expired by now...in reality I think it was invented by Eiwin Skaaning, owned by his compagny, which he left and founded AT
As to my bad mannered outburst about the Fs and Xmax
Just to be clear...16mm(pp) linear Xmax is the same as 8mm+/-
I really dont see the need fore such almost sublike Xmax when Fs is 37hz...where will it rolloff in a box?...40hz?...try and look at how much 16mm really is
If I intended to play that loud I wouldnt use a 6"
My point should have been that the energy lost in huge Xmax could be used better elsewhere...like greater SPL and powerhandling, and maybe even FR response
Its ok to call a 6" a midwoofer, but in reality its job is mostly also in the midrange...and the most important one, in my opinion
I think that huge Xmax is plain simply "good" marketing
Hey guys, in that SS flyer "Preliminary Specifications" there are no Vas values?
Would have liked to have punched in a few numbers and see what box alignment could be had. Suspect they left it out on purpose, for now.
The Fs is reasonable for a 6.5" but nowhere near other SS midbass drivers, sub 30Hz. As a consequence, the Vas will be lower as well since it's MMD is similar. But low FS is not a prerequisite for low bass. I use a driver array that has Fs = 48 and get flat in room response to 30Hz and usable down to 25Hz. So the higher Fs in itself is not the total story. If the parameters balance out you can gain almost an octave below Fs.
Would anybody hazard a guess what the Vas value might be?
Joe R.
Would have liked to have punched in a few numbers and see what box alignment could be had. Suspect they left it out on purpose, for now.
The Fs is reasonable for a 6.5" but nowhere near other SS midbass drivers, sub 30Hz. As a consequence, the Vas will be lower as well since it's MMD is similar. But low FS is not a prerequisite for low bass. I use a driver array that has Fs = 48 and get flat in room response to 30Hz and usable down to 25Hz. So the higher Fs in itself is not the total story. If the parameters balance out you can gain almost an octave below Fs.
Would anybody hazard a guess what the Vas value might be?
Joe R.
Perfect match fore almost any hifi midrange driver...less attenuation sound better, and if you are lucky NOT to need any attenuation at all you get even better sound
tinitus said:
OK thanks. Seems logical enough when put like that.
Most real subs are pushing 25mm one way. I don't think 8mm is excessive for a 6.5". It might be more than what other companies are offering at present but we simply don't know if that's to viewed in a negative light or not just yet. Once the drivers are available and people have had some time with them then we'll get a clearer picture. But for now I think its a little premature to dismiss a design based on the xmax of a preliminary spec sheet.
No guessing needed, Vas can be calculated from Cms and Sd (many T/S paramters are ambiguous):Joe Rasmussen said:
Vas = Cms * Sd² * d * c²
d: air density, c = speed of sound
And Cms we can get from Mms and fs:
Cms = 1/[(2pi * fs)² * Mms]
But I'm lazy.... my simulator proggy (Akabak, from its handbook I took the formulas, btw) gives the following values (it does the transformations at request):
6.5": Vas = ~36L
5.25": Vas = ~12L
Counter checking with Rms and Bl looks ok, got same values as given in the prelim. datasheet.
Those woofers look like also being well suited for open baffle designs (not for high SPL, though).
And with little cone excursion (in CB, not driven into sub-bass regions) they might be extremely linear, given the Xmax and the underhung coils.
Klaus
Their Xmax is given at 3%THD, while others spec it at 10%. There is nice paper from Klippel which shows that Xmax specs have to be taken with a grain of salt:
http://www.klippel.de/pubs/Klippel papers/Assessment_of_Voice_coil_peak_displacement_XMAX_02.pdf
- Klaus
http://www.klippel.de/pubs/Klippel papers/Assessment_of_Voice_coil_peak_displacement_XMAX_02.pdf
- Klaus
KSTR said:
Quite correct, I was being lazy. 😀
And looking at the Fs & Mmd as well as Sd, 36L would be about right. When SS gets around to publishing it, then we shall be able to confirm.
Joe R.
Lifted straight off Audiotechnology website:
Ejvind Skaaning was the guiding force behind several loudspeaker companies in Denmark; among the most prominent are Scan-Speak and Dynaudio corporations, both founded by Mr. Skaaning.
Joe R.
Ejvind Skaaning was the guiding force behind several loudspeaker companies in Denmark; among the most prominent are Scan-Speak and Dynaudio corporations, both founded by Mr. Skaaning.
Joe R.
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