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3wayaddict 27th June 2018 10:28 PM

Seas Excel W18EX001 vs Scan-Speak 18M/4631T00
Back at it again with another question.

For my 3-way build I was planning to use a Seas Excel W18EX001 as mid to cross with my Fountek NeoX3.0 at 2 kHz but I recently saw nearly everyone using a NoeX3.0 saying they cross it at at least 2,5 to 3 kHz because it should sound way better. So I got in some trouble with the mid woofer. On the frequency response graphs the Seas Excel W18EX001 seems to just make it to 3 kHz on- and 30 off-axis but when I was researching if it can actually do that because 3 kHz is pretty high for a 6,5" I saw many reviews saying it has cone break up at 1,7 kHz and the highest possible crossover frequency should be at 1,6 kHz but when I looked up the source from where the people who said that got that information, Zaph, it was indeed the magnesium cone W18EX001 but it seemed to be an older version. It was reviewed in 2006 and has a way smaller motor on the picture. And at the same time I saw people using it to about 2,5 - near 3 kHz so as you could imagine, I got confused.
So can I use a Seas Excel W18EX001, brand new, latest version which is on the website of Seas right now, to between 2,5 - 3 kHz?

I've already picked replacements in case it can't play to above 2,5 kHz: the Scan-Speak 18M/4631T00 or it's little brother the 15M/4531K00. Which one purely depends in aesthetics. I will just pick which one depending on which one I find to look better in my design. Shout at me for compromising sound quality but I don't care because they both sound amazing. The 15M has a lower moving mass and better dispersion but so slightly it's practically irrelevant, the bump starting at 1 kHz is way bigger and it doesn't get as loud. The 18M still has a amazingly low moving mass, the bump is smaller and it gets to 110,2 dB which is insane. I aim at 110 dB, with baffle step if a certain woofer doesn't get to 110 dB at it's own (which is nearly always the case). The normal W versions of these woofer are already known to sound amazing anyway so these M versions should sound even better for my midrange application.

But if it can play to at least 2,5 kHz without any problems I will certainly prefer and take the Seas Excel because it also has amazing specs. Because of it's magnesium cone. Because of it's large, powerful motor it has an amazing impuls response, even better than mid-level Accuton and in my opinion it looks amazing. And I initially picked it because of those characteristics. If it works, I love it.
And all of these nice features have got it even better reviews than the Scan-Speak. It should sound more neutral and accurate.

BTW, when doing research for if this would work or not, I noticed the crossover makes all the difference here. So to inform you of my capabilities, I use a MiniDSP 2x4 to control it and do all the corrections. Separation is being done by a passive filter, but just the separation. Everything else is handled by the DSP making a sort of hybrid crossover. I do it this way because I also need two outputs of my DSP to control the subwoofers (they are just the woofers in the towers but subwoofer drivers so they go very low) and I didn't want to have to use two MiniDSP 2x4's and something with more channels in one unit didn't fit my budget.

andy2 28th June 2018 12:30 AM

I think it's more than just crossing at this freq. or that freq. It depends on how it is crossed and using which order filter. You may also have to use a notch filter for the Seas. The Seas will have a lot more resolution vs. the Scan Speak. I have used the Scan Speak Revelator and Illuminator and although there are very good drivers, I think at the end, both being paper, and no matter how good they are, there is a limitation on how much resolution the paper material can muster. I personally would go with the Seas if it means having to work harder on the xover. The Seas will have a lot more resolution especially on the low frequencies.
As for the tweeter, I personally don't like the ribbon. I would go with a good dome and cross at 2khz.

3wayaddict 28th June 2018 06:47 AM

I was planning to use 2nd order because that's the recommended but if you think something else would be better, tell me. I have the ribbon because no dome tweeter of my around €150,- budget has the bandwidth and smoothness I want. And anyway, if you don't like ribbons, that doesn't mean I have to dislike them as wel.

Mario Pankov 28th June 2018 08:06 AM

18M is a midrange with foam suspension (confirmed by Scanspeak, I asked them by e-mail as some websites list it as SBR), high Qts and shortened voice coil. You should be really comparing the Seas with the 18W/8531.

My 2c on this - the motor of the Scanspeaks is much superior to the Seas but that is less important if you limit their excursion. The Seas would need to be used really not above 1.6Khz - the cone resonanse peak is centered at what looks like 4.8Khz, 3rd harmonic distortion will be spiking at around 1.6Khz. That means you`d have to pair it with a large waveguide or use 24db/slope as few tweeters can do that low. The Scanspeak also has higher cone area - 152sqcm vs 126 for the Seas so it will move less for the same sound level. The breakup, if used without a crossover, sounds like someone is blowing in an aluminium pipe and it can be excited by tones corresponding to the 1.6Khz frequency as it will produce its own harmonics. But these metal cones do produce bass really better than paper in my opinion.

The problem I have with the 18M is its way too efficient so will need padding or more SPL support from below. Look up a thread I started on it vs the 18W - its somewhere in Multiway - hificompass has measurements of the driver and it looks very very good.

3wayaddict 28th June 2018 11:40 AM

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I don't think Sd is to important. Moving more air is just louder right? Yes the 18M can get wayyy louder dan the Seas but not just the Seas but it the 18W which you say is a fairer comparison doesn't get as loud as the Seas. The SPL depends on more than just Sd and the effect of moving more air in terms of better bass response also doesn't matter to me at all since I will use it as mid. You often mention bass but I don't care about the 18W being able to produce better bass. These will be my mid in my 3-way towers. These are the drawings (still with Seas). The driver we are discussing now is the mid on top. At the bottom are two 8" SB-Acoustics SB23MFCL45-4 subwoofers they will play to between 200 and 250 Hz (I'll play with that with the DSP) so the mid has to play from that to 2,5 - 3 kHz.

It seems pretty obvious to me that the 18M is better for my application because it is actually designed to be used as a mid, has a better frequency response in the intended range, lower moving mass and so better impuls respons. What should make the 18W better for me as a midrange?

3wayaddict 28th June 2018 11:41 AM

But so to be clear. You're saying that I cannot use the Seas as my mid from 200 - 250 Hz to 2,5 - 3 kHz?

3wayaddict 28th June 2018 11:45 AM

Oh and another probably pretty important thing. In the other thread about these Scan-Speak you were all talking about the 0,707 Qtc in a sealed enclosure. Why, is this some miracle number? And do I need to have it as well for my midrange enclosure? What happens when it is not 0,707?

TMM 28th June 2018 12:03 PM

The W18EX001 is really better suited as a woofer because the peak in the frequency response boosts up the non-linear distortion components to unfavourable levels at much lower frequencies than it occurs at. See:

To avoid the peak in 3rd order harmonic distortion at ~1.7kHz you'd want to cross around 1kHz, to ensure that there is already significant attenuation of the fundamental at 1.7kHz and therefore significant attenuation of the 3rd order harmonic which lands on the 5kHz cone breakup peak. The benefit of metal cone drivers is that there is a region about an octave wide over which there is less breakup than an equivalent paper cone driver - for the W18EX001 this is perhaps 800Hz-1.5kHz, which translates into very low harmonic distortion from about 200-500Hz making it an excellent woofer.

The 18W/8631 doesn't have this problem due to its benign cone breakup behaviour, so you can cross as high as you want.


Originally Posted by 3wayaddict (
Oh and another probably pretty important thing. In the other thread about these Scan-Speak you were all talking about the 0,707 Qtc in a sealed enclosure. Why, is this some miracle number? And do I need to have it as well for my midrange enclosure? What happens when it is not 0,707?

in box response of Q=0.707 somewhat simplifies the crossover design as it is a perfect 2nd order butterworth response. Therefore when you combine it with a 2nd order butterworth electrical it creates a perfect 4th order linkwitz riley acoustical response. If you plan on crossing at a different frequency than the box Fb, sizing the box to achieve a lower Q (make the box bigger) will make designing the crossover easier as the acoustical slope that you get from the box will be more gradual and won't cause a big 'hump' in the response where you don't want it.

3wayaddict 28th June 2018 12:13 PM

So long story short. I can't use the Seas as my midrange from 200 - 250 Hz to 2,5 - 3 kHz so we'll scrape that one from the list., it's done for.
Then the Scan-Speak argument. 18W vs 18M. I think it's pretty obvious the 18M is better as a midRANGE than the 18W but bring your arguments. Again I DO NOT care about it's performance as woofer but only in it as a MIDRANGE playing MIDRANGE frequencies from 200 - 250 Hz to 2,5 -3 kHz. I do not care about bass performance.

Mario Pankov 28th June 2018 12:37 PM

Any midrange with a size of the 18M will start beaming at 2Khz or so, for your crossover point a Satori MR16 driver may be better suited.

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