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vann_d's 4 x FicarIB318 build

20K views 40 replies 15 participants last post by  thejck 
#1 ·
Drivers arrived today from Ficar! 4 big ole boxes. Everything seemed to be smartly packed and there was no damage even though one of the boxes had seen some abuse.

My wife is scared and she should be...:hsd:
 

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#4 ·
Ha ha! They would be ginormous salads!

Build quality looks great to me. You can tell they are hand assembled. Honestly, they look over-built. The rubber surrounds are big and thick. I can't imagine one failing. The spider seems super heavy duty. They look like they could handle so much more power than 500W based on the soft parts. Of course, they probably can because I think that is power in IB to hit xmax at 20 Hz.

I did not ask for the logos to be removed (not installed). They just came that way. Maybe Scott is doing this to make the HT crowd happy. Personally, I think the logos are fine and I wouldn't have minded them at all. Of course, I'm doing a manifold install anyway so it wouldn't have mattered.
 
#7 ·
The motor structure is not huge and the magnets do not appear terribly strong. The efficiency of the system and the power handling is where these seem to rock in an IB config. My WinISD model shows the four of them at over 94 dB 1W/m, which is very sensitive for a subwoofer. The large xmax (30mm) and their innate characteristics mean that a sub(infra) sonic filter is not required at even the lowest frequencies if power is controlled.

I'm actually going to be under-powering them by about 500W but I really don't need another 3dB of headroom with this system. In actual use, I'll probably max out at about 30W apiece and be hitting well over 100dB at the LP. I think I have headroom for full reference at LP but I don't anticipate listening that loud. This will keep woofer displacement way down and distortion very low.

I have never had or heard a system that will compare to the one I'm now building so there is the chance that I will crank the volume louder than ever before because of the clean sound I will be getting. Needless to say, I'm very excited to get the build completed!:D
 
#10 · (Edited)
I'm not sure how these will sound but I doubt I'll be disappointed. The system q with the Fi's should be between .6 @ .7 which is right about where many sealed boxes are designed. I would expect there to be plenty of "slam".

I think some who have been disappointed may have used drivers not suited for IB. For example, if a RE XXX was used the low end would be killer but the sound would lack some punch because the system q would be too low.

Of course, so people do like distortion. ..
 
#16 ·
Well it's been a long time since an update to this thread. Trying to finish a basement, speakers, and subs all at the same time really draws things out. The basement took priority as it was obviously the first thing that needed to get finished. It's at about 98% now with some paint touch ups and a couple small details to finish. I've got one of my three main speakers in a functional state and finally the manifold for one of the subs is hung. The attachments show the front of the baffle wall and a single manifold behind. Subs will be firing through the red grills on either side of the tv (grill on left not finished). I hope to have this manifold populated and functional this weekend! More updates to come soon.
 

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#18 · (Edited)
Finally, finally, finally got both my manifolds installed! :yay2: Sorry in advance for the poor quality phone pics



To dos:
-additional bracing between vertical 2x4 studs along entire wall
-seal all gaps with caulking
-insulate
-apply drywall or plywood facesheet to unfinished side of wall


I'll probably be done sometime this summer, haha!
 
#19 ·
Here's some more images with a better camera (still not a great one though)...
 

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#23 ·
Another tip for those who might choose this path in the future:

If you are going to "front mount" the subs like I did, pull the rubber gasket off and reverse it. That big rubber gasket wasn't really meant for mounting the front of the basket. I pulled mine off and reversed them so that the thinner, solid side sat flush with my manifold and made a good seal.
 
#26 ·
I'm running them 15 dB hot at 90 dB. I like it this way but I typically listen at -20dB levels. I think it sounds really good like this.

That said I'm also not sure what Audyssey is doing with dynamic eq. I need to do more measurements with different settings, etc.
 
#27 ·
Vann, congratulations on the completion! There's a lot to like here. I really like the original design approach, with the manifolds behind the two red stripes, very sharp. The arch and the whole alcove the equipment is in looks great too. Finally, I like that you're watching the F1 race, I love having the system cranked up for 18k rpm engine passes.

How does everything sound??? Any issues from having the mains down close to the floor like that, with the glass table in front of the seat?
 
#28 ·
Beautiful installation! How come you didn't invert 1 sub in each manifold to cancel out distortion?
 
#30 · (Edited)
Thanks a bunch!

Well, I guess for the reason that I didn't think to. Would the correct method be to invert one and also wire out of phase? (i.e. drivers firing out of phase but cone motion/vibration cancelling) I put them "opposed" to help cancel vibration. Inverting one would require the out-of-phase wiring to accomplish the same.

Now, I skimmed the thread you posted and it appears that yes, I should have them wired out-of-phase if I chose that alignment.

The difficulty for me would be related to installation. I would need to exchange my wood screws for threaded fasteners and inserts. Not sure if I have the real estate for that. Also, man-handling the sub into place would be difficult!

Edit: I guess I could still mount from the outside of the "plenum". Maybe I'll have to try it and see if I can measure differences...
 
#33 ·
A push-pull approach does possess measurable distortion lowering advantages in small sealed subs, and especially IB subwoofer systems.

As one can imagine, and similar to most all things subwoofer related ... there's much myth and misunderstanding about such techniques. Take any normal, double-driver, small sealed sub, ie., the monster JTR Captivator S2;




Obviously, both cones work together to create waves of bass. The cones are both mechanically in phase, and electrically in phase. To implement a push-pull approach, flip one driver around backwards, and flip it's polarity too. As one can see, the drivers are still working in concert with one another, and it's sensitivity and maximum output haven't changed at all.

What has changed is the manner in which the driver's acoustic energy sums together. The result is odd ordered harmonics are cancelled out. Magnetically, there exists a small asymmetry between the forward stroke, and the rearward stroke of the cone. Designers try to keep this as small as possible, but it's just a product of the magnetic motor/voice coil approach of dynamic drivers.


Essentially, any anomalies in the driver's cone, surround or spider, or magnetic properties through the stroke, are simply canceled out by the flipped driver's opposite characteristics.


Since the coil is moving, and the permanent magnetic element isn't, there's some non-linearities over the course of the stroke. The specifics are beyond the scope here, but combining the even ordered nonsymmetrical non-linearities (including the aerodynamic of the structure/basket, the spider, surround), then entirely nulling them by flipping one driver's orientation and polarity, is a distortion lowering technique that has merit.

The odd ordered harmonics remain, yet the even ordered are lowered. A small sealed, like the JTR CapS2, benefits, however the air volume loads the drivers, and although there's benefits, they're somewhat lessened. That said, conversely ... an IB subwoofer system utilizing a push pull approach fully benefits from this technique. The drivers need to be relatively close to one another, but given the sizable wavelengths being produced, typically this isn't an issue.


Now, why don't more mfrs make their subs this way? It's difficult to implement the reversed driver. Also, although THD is lowered, the remaining odd ordered harmonics are oftentimes the most objectionable subjectively, the even being somewhat more tolerable. THD is lowered in push pull, period. Some of the finest studio monitoring systems in the world, the TAD based Kinoshita systems (Rey Audio), can be upgraded with their sub system, which is push-pull. They've been offering 9hz extension playback since '91.




some Kinoshitas demoed, for sale. They use TAD drivers, if you've never had the pleasure to experience TAD, they're superb.


I hope this helps
Thanks



btw ... found a push-pull pro audio, vented sub by EAW;

 
#34 ·
FOH,

Good thing you're everywhere. ;)

Even with those improvements, in real world practice, do you think it is more commonplace that said improvements would overshadowed by the increased mechanical transference? Maybe I just need to flip the phase on a couple of drivers and see what mechanical impact is has. Perhaps I'm assuming it to be more than it really is?
 
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