rms8
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Post by rms8 on Sept 8, 2012 8:08:32 GMT -7
Hi All! Got some question regarding an IB install I will be doing around the April 2013 time frame (when the home is complete and I can start on the HT in the basement). Drivers = Eight Fi-IB318's. (4ohm ea) store.ficaraudio.com/ib318/Amplifier = LabGruppen knockoff FP14000 Enclosure = 885 cubic ft (works out to ~ 8.2 x VAS) Since this amp is over kill for an IB, I was considering using a single channel to power the IB setup : @ 8ohm = 2x2350W @ 4ohm = 2x4400W @ 2ohm = 2x7000W With those figures in mind, I am trying to think of a suitable wiring scheme for the subs and wanted to see if anyone had objections/ideas... 3 x IB318's in parallel = ~ 1.333ohm 3 x IB318's in parallel = ~ 1.333ohm 2 x IB318's in parallel = ~ 2ohm That covers all eight drivers. Then wire the two 1.333ohm set in series to get 2.666ohm, then wire that output in series with the 2ohm set to get ~ 4.666ohm load for a single FP14000 channel ( ~ 4400W). Would this work or is it too unbalanced (series/parallel-wise) ?? I am looking into a MiniDSP box www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4 to use as a highpass filter to protect the drivers from bottoming out. Regarding the use of the HP filter for protection, what cutoff frequency, filter type (Butterworth, LR or Bessel) and slope would you recommend? Thanks!!!!!!!!!!!!! Rob |
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Post by ThomasW on Sept 8, 2012 16:31:28 GMT -7
Forget about the amount of power per channel
Do 4 drivers per channel, series/parallel wiring to get a 4 ohm load.
HP frequency is up to you, use 24dB L/R
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rms8
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Post by rms8 on Sept 9, 2012 16:27:59 GMT -7
HP frequency is up to you, use 24dB L/R Thanks for the reply Thomas! What would be a good SAFE cutoff for the HP considering I will have more power for these drivers than they can use? I assume since I will have 8 drivers, I won't have to push the gain very much at all. I have two of the original Buttkicker 1900W amplifiers as well. Would it make more sense to use those instead since the FP14000 has considerably more power than those eight drivers will need? I could then use the FP14000 to power the 6 Buttkickers (2 original designs and 4 LFE's) since those are power hungry devices. |
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Post by ThomasW on Sept 9, 2012 22:02:05 GMT -7
IB drivers don't unload like drivers in ported subs. So the choice of HP frequency is a function of how loud the IB is going to be played
IIRC BK doesn't recommend their amps for music.
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Ile
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Post by Ile on Sept 10, 2012 4:25:02 GMT -7
No HP needed if you aren't planning over 130db output. Most main speakers blow before 130db, so your IB should be safe if it's matched to speaker level.  Attachments:
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rms8
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Post by rms8 on Sept 10, 2012 4:48:22 GMT -7
Thank you both!
I don't think I would ever consider running any system at 130dB. But even level matched isn't there infrasonic info in soundtracks that would really excite these drivers to Xmax even at normal or reference levels? Or should I assume that having eight of them would keep each driver so low in power consumption that it should never really be a concern?
Also, is that WinISD?
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Post by ThomasW on Sept 10, 2012 6:29:47 GMT -7
But even level matched isn't there infrasonic info in soundtracks that would really excite these drivers to Xmax even at normal or reference levels? A few DVD contain contain extremely low frequencies 3-5Hz in some instances. If you want to bullet-proof your system use a 10-12Hz HP provided you have a normal size room and are operating the system at reasonable output levels. If your room is the size of a basketball court or you really like 'live' sound of headbanging def metal, the raise the filter to 15Hz |
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Post by FOH on Sept 10, 2012 16:12:16 GMT -7
A few things; Yeah the amp is big-time over kill, ... when it works ...  just saying ... No Regarding the load impedance and config of your drivers, do what Thomas suggested, as current/voltage must be the same per coil. Regarding the HP filter, really unknown because of the 8xVAS scenario. Perhaps that loads the drivers in a way whereby the HP filters others have implemented wouldn't apply here,..I don't know. Experimentation is in order. No modeling could accurately tell you either. Likewise, wrt the 8x VAS, I believe the Fi's aren't as sensitive down in the deepest octaves, so you may need some measure of LT type boost @ 10hz or so,...again, just thinking aloud. ----- You may be surprised The deep, deep stuff isn't too offensive and subjectively isn't overly loud, thanks to the EL curves. ----- Yep, but it's dependent on how you "salt to taste"  Good luck btw;
OT, but 3 days at Cedia, ... the finest, most powerful and dynamic playback I believe I may have ever heard in one of the demos. |
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rms8
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Post by rms8 on Sept 10, 2012 17:39:20 GMT -7
Regarding the HP filter, really unknown because of the 8xVAS scenario. Perhaps that loads the drivers in a way whereby the HP filters others have implemented wouldn't apply here,..I don't know. Experimentation is in order. No modeling could accurately tell you either. Likewise, wrt the 8x VAS, I believe the Fi's aren't as sensitive down in the deepest octaves, so you may need some measure of LT type boost @ 10hz or so,...again, just thinking aloud. When I factor in the baffle which the drivers will mount to (sort of a shelf/step jutting out from the bottom of the front wall), I gain another 52 ft3 which makes the VAS 8.7X. How much do you think this hurts the performance by not being at least 10X VAS? From your comment of needing some sort of "LT" (did you mean LF ??) boost @ ~ 10hz, it seems I may be able to bypass the HP filter? I really don't need the subs to re-create content that low since I will have several buttkickers mounted to the platforms to impart that visceral impact. Thanks for all the input thus far! |
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Ile
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Post by Ile on Sept 11, 2012 2:32:12 GMT -7
I don't think I would ever consider running any system at 130dB. But even level matched isn't there infrasonic info in soundtracks that would really excite these drivers to Xmax even at normal or reference levels? Or should I assume that having eight of them would keep each driver so low in power consumption that it should never really be a concern? Also, is that WinISD? That near x-max point (29.5 mm) is with 2 Hz signal. Same power gives you 132db near field in upper range, so I would consider this pretty safe if you doesn't use +120db levels in listening position. Yes, curves are made with WinISD Pro ALPHA. 1W gives 98db at near field with 0.6 mm excursion at 2 Hz, so you should get about 90db to your listening position with 1W. I have just two FI IB3 drivers without HP and those seem to be more than enough for my small room.  |
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rms8
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Post by rms8 on Sept 11, 2012 6:08:51 GMT -7
I should have stated this earlier....
Room is
10(h) x 27.5(l) x 22(w) feet
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Post by FOH on Sept 11, 2012 6:53:53 GMT -7
How much do you think this hurts the performance by not being at least 10X VAS? Honestly, I've no idea. I didn't intend that inadequate volume was an negative issue that couldn't be overcome. I'd think other factors may impact the potential outcome even more. The over-all solidity and striving for an entirely inert platform would be very important. Taking steps to mitigate any reflected energy or disturbances in the immediate area behind the drivers, as to not influence and corrupt the direct energy off the cones, would be important. And most importantly would be ideally optimizing and blending the IB energy with that of the remainder of the system and room. From your comment of needing some sort of "LT" (did you mean LF ??) boost @ ~ 10hz, it seems I may be able to bypass the HP filter? I really don't need the subs to re-create content that low since I will have several buttkickers mounted to the platforms to impart that visceral impact. I meant LT, as in Linkwitz Transform. "Some measure of LT type boost". Yeah, with the slightly diminished backspace, and the Fi's inherent roll off down low, perhaps some added boost may be desired. Regarding the need of a high pass, it's up to you. That amp is so powerful, I'd think the big, high level, low freq effects could do some excursion damage if the conditions were right. The only way to know would be to slowly explore the limits with some hotly recorded LF/LFE material and little by little explore the combo of all the factors. I'd recommend BluRay releases such as the work of sound designer Randy Thom (War of the Worlds, How to Train Your Dragon) as he utilizes the entire LFE spec down to 3hz. I really don't need the subs to re-create content that low since I will have several buttkickers mounted to the platforms to impart that visceral impact. You may find you prefer both the pressure of the cones, and the tactile component from the Buttkickers. Be mindful of signal alignment and adequate delay of the tactile rig, ... uncorrelated may be more of a distraction than anything. I too am exploring the use of IB/tactile transducer combo, and alignment and level is critical. Good luck |
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Post by FOH on Sept 11, 2012 6:57:44 GMT -7
I should have stated this earlier.... Room is 10(h) x 27.5(l) x 22(w) feet +6k cubes, ..... (8) Fi IB3-18s isn't overkill, in my opinion. |
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rms8
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Posts: 48
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Post by rms8 on Sept 11, 2012 8:20:01 GMT -7
How much do you think this hurts the performance by not being at least 10X VAS? Honestly, I've no idea. I didn't intend that inadequate volume was an negative issue that couldn't be overcome. I'd think other factors may impact the potential outcome even more. The over-all solidity and striving for an entirely inert platform would be very important. Taking steps to mitigate any reflected energy or disturbances in the immediate area behind the drivers, as to not influence and corrupt the direct energy off the cones, would be important. And most importantly would be ideally optimizing and blending the IB energy with that of the remainder of the system and room. I meant LT, as in Linkwitz Transform. "Some measure of LT type boost". Yeah, with the slightly diminished backspace, and the Fi's inherent roll off down low, perhaps some added boost may be desired. Regarding the need of a high pass, it's up to you. That amp is so powerful, I'd think the big, high level, low freq effects could do some excursion damage if the conditions were right. The only way to know would be to slowly explore the limits with some hotly recorded LF/LFE material and little by little explore the combo of all the factors. I'd recommend BluRay releases such as the work of sound designer Randy Thom (War of the Worlds, How to Train Your Dragon) as he utilizes the entire LFE spec down to 3hz. I really don't need the subs to re-create content that low since I will have several buttkickers mounted to the platforms to impart that visceral impact. You may find you prefer both the pressure of the cones, and the tactile component from the Buttkickers. Be mindful of signal alignment and adequate delay of the tactile rig, ... uncorrelated may be more of a distraction than anything. I too am exploring the use of IB/tactile transducer combo, and alignment and level is critical. Good luck Here is a link to the design I did for the home theater. The HT portion is actually under one of the garages (spancrete) so the walls behind the framing are concrete. Of course there is much more to the room than this drawing, but it gives you the overall birds' eye layout. i441.photobucket.com/albums/qq137/rms8/Home%20Theater/Basement_revised_NEWest.jpg |
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Post by FOH on Sept 11, 2012 12:40:33 GMT -7
Nice,
What type of seating distance and seating layout? ie., multi-row theater seating, or comfy furniture style?
I'm guessing you're all over it, but consider bass trapping inherent to the wall structure if possible. The concrete backer surfaces will make for some sharp Qs otherwise. So some lossy, multi layer deadening would be sweet, in addition to all the velocity based trapping you can get away with.
The more I look at this, you'll likely need all eight of those drivers.
Good luck
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rms8
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Posts: 48
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Post by rms8 on Sept 11, 2012 15:52:28 GMT -7
Nice, What type of seating distance and seating layout? ie., multi-row theater seating, or comfy furniture style? I'm guessing you're all over it, but consider bass trapping inherent to the wall structure if possible. The concrete backer surfaces will make for some sharp Qs otherwise. So some lossy, multi layer deadening would be sweet, in addition to all the velocity based trapping you can get away with. The more I look at this, you'll likely need all eight of those drivers. Good luck Seating will be similar to what I currently have. Roughly 15' from screen. Two rows. I do like comfy couches, but wife has wanted theater seating for so long. I'll probably do two rows of 4, with middle seats in each row dividerless (making it like a love seat). There will be a permanent platform built for the second row which will cover where the conduits coalesce. Each row will actually rest on a mini-platform of sorts, only a few inches high. It will contact the floor (or platform for 2nd row) via rubber isolators. These Isolators will not be in the corners as one would typically think to spread the load. Instead, the will be fastened more towards the center allowing this mini-platform to deflect if you were to step on to it or stand on the edge. This "bounce" or "spring-e-ness" is what allows the buttkickers to really SHAKE the seats (the whole mini-platform actually) since the buttkickers are mounted to the edge of the platform. I created this concept in my current HT and the results are astounding to say the least. Mount one in one corner and the other would be chatty-corner from it and out of phase. Regarding the basstraps, they will be filled with layers of batt insulation. I haven't researched too much (YET!) resonating basstraps, but I plan on it. The room will have dry stacked stone walls with DIY acoustic panels. There will be four large faux wood beams (2 each side) going from floor to soffit (soffits will actually be two stepped). Been going over this design for over a year now making several tweaks over the time. |
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