# Deadicated midbass: thoughts about Scanspeak Illuminator 18WU/4747T-00?



## 24th-Alchemist (Jun 16, 2011)

I'm thinking about buying some Scanspeak Illuminator 18WU/4747T-00's for dedicated midbass (63-255 Hz). (See madisound; I can't post links yet b/c too few posts). Any comments on these?

I'm interested in the 18WU/4747T-00's because they are 7-inch drivers with a one-way linear listed at a whopping 9mm.

I'm constrained to midbass drivers that are no larger than 6.5 to 7 inches. I've been running 6.5-inch CDT M6's in the front doors in 0.5 cu ft sealed (the M6's seem like a variant of the peerless SLS). I think the speakers sound great in the 63-255 Hz range -- good attack -- but unfortunately I need to cross them at 100 HZ 24 dB/oct acoustical to stop them from bottoming out at the volumes I'm shooting for. I'd like to cross at 80 Hz tops, 63 Hz even better (24 dB/oct), but at a highpass below 100 Hz the M6's just don't seem to be able to handle the accompanying excursion at high volumes. (I've recently broken a second set).

My thoughts are that the combination of the relatively small cone area with a limited Xmax is the issue here. Best would probably be to use an 8-inch for more cone area, but the space just isn't available. Hence the 18WU/4747T-00 is appealing b/c of its stated 9mm one-way linear excursion and 16 mm one-way max excursion. Scanspeak provides a speaker response model in a MS Excel spreadsheet and the prediction is that in 0.5 cu ft sealed the 18WU/4747T-00's will have a Q of ~1 at a cutoff freq of ~90 Hz -- not good, but EQ is not a problem and I can use a Linkwitz compensator to cancel their undesirable high-Q pole and get an acoustical 24 dB/oct response with a more desirable Q (e.g. a Linkwitz rolloff) at any reasonable highpass frequency.

I have a spare set of new M6's but my experience leads me to believe that installing a third pair of M6's will be futile.

Any remarks on the rational outlined here?


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## 24th-Alchemist (Jun 16, 2011)

Well I dug up the old "blown out" pair of M6 midbass drivers, and although they're specified as having a "10 mm peak Xmax", based on my measurements they'd be lucky to move a full 10mm in either direction. (And I was pushing hard because they're broken -- they're close to moving a full 10 mm though).

The more I think about it, the more I think my problem is that these drivers are limited by excursion -- I'm not going to be able to take advantage of their stated 150W RMS power handling capabilities at frequencies in the 63-85 Hz range, because the associated excursion at such freqs is just too large.

But wouldn't this apply to any 6.5-inch driver? Isn't it just physics? If I can't fit a cone larger than a 6.5, it seems that if the M6's are running into excursion bounds that limit SPL in the 63-85 Hz range, any driver that will even have a chance at providing more SPL in the 63-85 band must have a peak Xmax larger than the 10mm of the M6's.

I'm curios about the "pro audio driver" idea, what does that entail?

I'm actualy surprised nobody has used the illuminators, although at ~$300 / driver I guess I can understand why.


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## Wesayso (Jul 20, 2010)

DIYCable.com : Intro » Home » Exodus Anarchy »

Is this an option? Sensitivity is higher than the CDT M6 and so is Xmax. 

Edit: just saw the xmax on the M6 reported at 12mm, so they might be too similar.


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## 24th-Alchemist (Jun 16, 2011)

Actually the Exodus EX-Anarchy Midwoofer is an interesting option. Thank you.

It's tricky because CDT offered the M6 and the M6+ -- both of which I think have now been reincarnated into other model numbers. The M6+ had a huge excursion (12 mm peak Xmax) and looked like a minisub (perhaps its the driver referred to above). However, CDT communicated to me via email that they felt the regular M6 would be superior to the M6+ for true midbass, including the 63-85 Hz range that has been troubling me. Consequently I never tried the M6+.

I intend to look more carefully into the Exodus EX-Anarchy Midwoofer.


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## t3sn4f2 (Jan 3, 2007)

Erin (Bikinpunk) uses the Illu. paper coned version as a pure midbass in an AP alignment in the kicks (venting outside) and loves them. IIRC he mentioned that they are running without a highpass and thats with a 300 watts a piece. He said they kick the mighty Revelator's ass in that app.

Zaphaudio also tested these AL version and said they are great for those that need the extra output down low iirc. Should still be in his blog entries.


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## 24th-Alchemist (Jun 16, 2011)

... when I wrote that I was "surprised no one is using the Illuminators" I thought afterwards that I should have wrote that I'm surprised there isn't more info on the web about them.

Anyway, I will definitely have to check zaphaudio (I'm thinking about the Al version, which I believe has an even larger Xmax than the papers).

Spec wise the illuminator seems ideal since I'm pretty sure excursion is the issue for me.

To be fair to the M6's though, I feel compelled to re-mention that IMO the M6's sound really good with great attack (in 0.5 cu ft sealed) -- I'm just looking for a little more low-end output.


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## ecbmxer (Dec 1, 2010)

Just out of curiosity, what amp/power are you gonna be running with them and are they going in sealed or IB and door or kicks?


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## ErinH (Feb 14, 2007)

t3sn4f2 said:


> Erin (Bikinpunk) uses the Illu. paper coned version as a pure midbass in an AP alignment in the kicks (venting outside) and loves them. IIRC he mentioned that they are running without a highpass and thats with a 300 watts a piece. He said they kick the mighty Revelator's ass in that app.
> 
> Zaphaudio also tested these AL version and said they are great for those that need the extra output down low iirc. Should still be in his blog entries.


all true.

I love 'em.


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## 24th-Alchemist (Jun 16, 2011)

> Just out of curiosity, what amp/power are you gonna be running with them and are they going in sealed or IB and door or kicks


Most of it is described above. They'd be in 0.5 cu ft sealed. According to a MS EXCEL spreadsheet provided by ScanSpeak, in 0.5 cu ft sealed they'd have a Q of 0.97 with an Fs_box of 87 Hz. The amp, for now, is a RockfordFosgate T400-2, although I might switch to a RF P450.4 bridged.

One concern is that if I went with the 18WU/4747T-00 I'd have to drive them hard below 87 Hz with a Linkwitz compensator in order to get them to play flatter down to my target HP of 63 Hz for an LR-4 acoustical response. I wonder if they'd have issues related to power handling instead of excursion.

I looked at reviews of both the 18WU/4747T-00 and EX-Anarchy at Zaphaudio, but both reviews were short and basically just said "good". What about all those graphs at Zaph? Anybody have insight into interpreting them?


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## ecbmxer (Dec 1, 2010)

Wow, don't know how I missed that info! I was just surprised to hear that you have been bottoming the SLS's. Everybody running them seems to say they are monsters and never bottom, especially sealed like you have. Maybe they just aren't up the task of the volume you're looking for. Sorry I'm not much help. Good luck!


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## 24th-Alchemist (Jun 16, 2011)

> I was just surprised to hear that you have been bottoming the SLS's


Technically I'm running CDT audio's M6's, which I think are similar to the SLS's, but perhaps I'm mistaken about the similarities.

I did try and measure the M6's max mechanical excursion, and I'd say +/- 10m (i.e. 10 mm one way -- which is their specified Xmax) is the absolute max they can go. (Actually I measured a little less).

In comparison the Scanspeak illuminators are specified as having a +/- 9 mm linear, and +/- 16 mm max excursion. That seems like a big difference to me, although I don't know if excursion that big in a 7-inch driver can yield a 100% return. I'd assume there's got to be a point where a driver of radius R starts to loose benefit from additional excursion beyond some distance X. I just don't know the relationship between R and X.

As for my concern about whether the Illuminators can handle extra power at frequencies just above 63 Hz (to bump up its early roll-off from its enclosure), the EXCEL model from Scanspeak indicates that the driver impedance will be high around those frequencies, so the current should be low and thus I'd assume thermal power handling wouldn't be an issue.

I'm also getting a little concerned that other people don't seem to be having similar issues. I wonder if there's something wrong with my set-up. What it could be I don't know, everything seems fine. The volume I'm looking for, yeah its loud, but it's by no means insane.


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## subwoofery (Nov 9, 2008)

bikinpunk said:


> all true.
> 
> I love 'em.


... yet you plan to swap them for another brand :laugh:  

Kelvin


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## ErinH (Feb 14, 2007)

Because something happened to one and I can't afford to replace it. Kind of made me go "oh, crap" these are too expensive to have this happen again. Great drivers. I've just changed my mindset about cash flowing a set of $600 speakers and these never come up for sale used.

Plus, I wanted to go tue 8" route. For 7" drivers, these are easily the best I've used for mid bass in my car.


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## cvjoint (Mar 10, 2006)

Late to the party.  The Scan's seem to be the best. Let me know if you want some professional quality results on them. I'm not likely to have these in my car before I win the lottery so that's your best bet. 

Imo, for midbass use, Zaph's reviews are just ok, you really need a Klippel. You can look at the nonlinear distortion plots to see if distortion climbs up towards low frequencies, that's a sign of motor strain. Remove the 7" drivers that have this pattern and see what you are left with. From there on you need higher output plots or a Klippel. There are plenty of speakers that fail this test. Good ones are the Anarchy in the blog and one of the Ushers in the comparo, surprise surprise.

Erin can I ask what happened to the Illum that broke, how did it happen?


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## ErinH (Feb 14, 2007)

^ I was comparing the illuminator to the exodus last night. The exodus distortion figures are better than the scan, however, it looks like the exodus rolls off a bit sooner (a smaaaall bit). That's the one thing that kept me from buying a pair last night. That and the fact that I really don't feel like re-doing my kicks. 

What happened? Me. That's what. TIghtening 'em down with a screwdriver and .... sliiiiip..... poked a hole in the cone. However, they actually perform very well still. I got 3rd @ MECA finals last year with them. Anyone who's heard my car in the past year has heard them with the driver's side midbass with a hole in it; though I did repair it the way the guys at Meniscus told me to.


Exodus FR:










Scan Illuminator FR:











Exodus Distortion:










Scan distortion:


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## cvjoint (Mar 10, 2006)

bikinpunk said:


> ^ I was comparing the illuminator to the exodus last night. The exodus distortion figures are better than the scan, however, it looks like the exodus rolls off a bit sooner (a smaaaall bit). That's the one thing that kept me from buying a pair last night. That and the fact that I really don't feel like re-doing my kicks.
> 
> What happened? Me. That's what. TIghtening 'em down with a screwdriver and .... sliiiiip..... poked a hole in the cone. However, they actually perform very well still. I got 3rd @ MECA finals last year with them. Anyone who's heard my car in the past year has heard them with the driver's side midbass with a hole in it; though I did repair it the way the guys at Meniscus told me to.
> 
> ...



I cringed when I read this. Happened to me, only worse. I was helping my bud install a pair of IDQs. We were in a hurry and used a drill with a short cable run. It slipped and went right through his surround. Holes in cones aren't as bad. Look at Accuton, it probably reduces cone modes 

The rolloff is nearly identical. The distortion performance is surprising. The only two things that I can think off:
*more power compression in the Scan
*the higher production variance of the Exodus, maybe this one has a true 12mm motor throw, that will do it.

I haven't used a $350 midbass in a while, not sure I'd enjoy it. Broke the surround off my 10" Excel in a heated listening session.

The nonlinear inductance of the Exodus seems to be overwhelmed by the other goodies. Looking at the two you can't really tell it's missing them (shorting rings).


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## subwoofery (Nov 9, 2008)

The Illum always had my attention but I couldn't justify me paying that premium for just midbass application... 
However I'm really interested in those, would like to know how it fares with klippel testing: 
SB Acoustics :: 6 1/2'' SATORI MW16R 

It's much shallower than the Illum. Should be cheaper too 

Kelvin


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## cvjoint (Mar 10, 2006)

You and me both, I didn't even know they made those. Looks like a mini Illuminator, a bit smaller in every way. 

The Vifa NE 7"s look similar, but do not test nearly as well as the Scan units. The suspensions are hella tight and they have about half the motor throw of the Scan.


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## cvjoint (Mar 10, 2006)

Courtesy of Voice Coil Magazine:

Exodus free air at 94db:









Illuminator free air at 94db:










Doesn't really look like Zaph's results does it? These ones make sense given the Klippel tests that come with them. My money is on production variance in the Exodus. Could also be some funky measuring artifact in Zaph's readings.

I will delete these from my photobucket quick so soak them up while you can.


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## subwoofery (Nov 9, 2008)

Which harmonic is the most offensive again? Odd ones? 

Kelvin


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## cvjoint (Mar 10, 2006)

subwoofery said:


> Which harmonic is the most offensive again? Odd ones?
> 
> Kelvin


higher order and odd. Basically the third is the evil, 4th and up are rarely loud enough.


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## subwoofery (Nov 9, 2008)

cvjoint said:


> higher order and odd. Basically the third is the evil, 4th and up are rarely loud enough.


Thanks... I guess that the Illum (based on your post) is still the better one for midbass applications - IMO the Exodus fares well too if used below 300Hz (therefore *PURE* midbass application). 

Kelvin


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## cvjoint (Mar 10, 2006)

subwoofery said:


> Thanks... I guess that the Illum (based on your post) is still the better one for midbass applications - IMO the Exodus fares well too if used below 300Hz (therefore *PURE* midbass application).
> 
> Kelvin


Yep, the Exodus does very well, especially for 65 bucks. The same exact test on a Vifa NE 7" that looks very much like the Scan ends up in 6% distortion at 50hz. That's 3 times more than the Exodus, and 6 times more distortion than the Scan. So yeah, I would say both the Exodus and the Scan are top notch midbass drivers. Ultimately you do get the best with the Scan, it's also gigantic footprint wise, so a bit of cheating imo. In HT I wouldn't care but car audio every inch matters.


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## subwoofery (Nov 9, 2008)

Knowing who's behind SB Acoustics, I can only imagine that the MW16R is gonna be a bridge in performance between the Scans and the Exodus. Who knows... maybe it'll be as good as the Scans which would be great seeing that there's almost 1" less depth  

Kelvin


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## cvjoint (Mar 10, 2006)

subwoofery said:


> Knowing who's behind SB Acoustics, I can only imagine that the MW16R is gonna be a bridge in performance between the Scans and the Exodus. Who knows... maybe it'll be as good as the Scans which would be great seeing that there's almost 1" less depth
> 
> Kelvin


That's one aspect. On the other hand what are they trying to achieve? Is it a good 3 way speaker like the Ill and Exodus or a 2 way driver like the Vifa?

Sometimes stuff just performs mediocre, look at this driver test using a similar basket to the Exodus, 9% distortion at 50hz and it's marketed as a sub:

http://www.wavecor.com/SW182BD01_in_Voice_Coil_Feb._2010.pdf


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## subwoofery (Nov 9, 2008)

Seeing the excursion figures and the freq response, I think it is more geared towards being a midwoofer rather than a pure woofer... so more a 2 way driver like the Vifa

Looks like there's a small impedance glitch around 1.2kHz which might be due to some resonance of the basket... 

Kelvin


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