|
Post by wookus on Sept 21, 2010 5:39:01 GMT -7
I seek your advice on driver choice. Total budget (including amps, etc.) is great - around $5k, since buying commercial subs to do what I want could run way over that; and I consider this a lifetime investment.
My theater/living room is about 2500 cu.ft. and the portion of the basement below it is about 2000 cu.ft. The manifold will be mounted between 2x10 joists that are 16" on center.
I realize I don't really need this much of a setup, but I've never been accused of being rational. I want effortless bass extension as low as possible (10 Hz?).
The three drivers that have really caught my attention are:
AE IB15 Exodus Maelstrom 21 SoundSplinter RL-p18
I was thinking of a total of four drivers in two manifolds and of powering all this with one or two Crest CC4000's.
What would you all recommend to do the job?
|
|
|
Post by ThomasW on Sept 21, 2010 7:09:30 GMT -7
Buying non-IB specific drivers is a waste of money since the large motor systems used for standard woofers designed for portable box subs aren't needed for an IB sub.
My recommendations are either the AE IB15"s or the Fi IB-15"-18"
|
|
|
Post by wookus on Sept 21, 2010 12:19:29 GMT -7
Thank you, Thomas. You just saved me a bundle of money!
In comparing the AE 15's, having a displacement of 3.07 liters, with the Fi IB318's, having a displacement of 7.26 liters, it would seem like the logical choice (ignoring cost) would be the Fi IB318's.
Using the savings you found for me I could even go with two manifolds, each one containing four of the Fi IB318's, for a total of eight Fi IB318's. Should that yield bass extension nice and low, say 10 Hz?
I should mention that my theater has pretty good acoustical treatment. When I built it I hired a pro to design the layout. He did a great job.
Thanks for your help, Dave
|
|
|
Post by jman on Sept 22, 2010 1:41:20 GMT -7
Eight of them will probably do 120db at 10hz. Two in each manifold will probably be enough so you could have 4 cutouts but cover 2. Then you can buy 4 more drivers if you really want more output.
|
|
|
Post by ThomasW on Sept 22, 2010 7:02:28 GMT -7
Do you have a copy of the floor plan you could post?
Having that would go a long way toward suggesting the number of drivers needed.
|
|
|
Post by wookus on Sept 22, 2010 14:36:42 GMT -7
I have attached the diagram for my home theater/living room acoustical treatment - hopefully I did it correctly and it will be readable. My apologies if it isn't - I'll try again in that case. Thanks, Dave Attachments:
|
|
|
Post by wookus on Sept 22, 2010 14:51:41 GMT -7
Just a little in the way of explanation of the diagram:
The two darker blue corners in the front are the main bass traps. They are 2' x 2' floor to ceiling and are stuffed with cotton insulation (like fiberglass but not as nasty to work with). The soffits are also bass traps. They are 1' x 2' all the way around and are filled with OC 703 rigid fiberglass insulation. The four surround speakers aren't shown. There are two SVS PB12 ultra subs against the back wall.
I plan to put the two manifolds in the floor between the screen and the sofa. I realize this is going a bit overboard, basswise, but I don't have to turn the volume up too much. I just want to get good low extension.
It wasn't until I started planning this project that I realized the true purpose of a living room floor is to house manifolds. There is so much unused space.
Thanks, Dave
|
|
|
Post by ThomasW on Sept 22, 2010 16:36:12 GMT -7
Thanks for the drawing make things easier for me.
I don't think you're going to need 8-18"s.
Start off with 4-18"s configured in pairs in two manifolds. If you want to hedge your bets build the manifolds with room for 4 drivers but just start with a pair in each.
|
|
|
Post by wookus on Sept 22, 2010 16:55:41 GMT -7
Thank you Thomas and Jman. I can't wait to get started. Though I'll have to wait a bit to buy the drivers and amp, I can get started on building the manifolds sooner. I'll size the manifolds to hold four drivers each (probably 48" X 14.5" floor opening), but will cover two of the holes to start, like you suggested. I'll post pictures as the project progresses.
Dave
|
|
|
Post by FOH on Sept 23, 2010 6:21:16 GMT -7
Wookus, Nice space, looks as if you have a lot of your acoustic aspects covered. I'm about to embark on a complete overhaul of the family media room. My room is approx. the same cubes and rectangular dimensions. So your design decisions are of particular interest to me. Questions; How do you characterise the sound of you room right now? I'm curious about the balance, ie..., LF absorption and HF absorption/diffusion.
How would you describe the response of your current subs in that space (overall response and extension)? What chiefly has lead you toward an IB system?
Have you made a decision regarding amplification and drivers, if not, which would be your ideal scenario?
Thank you
|
|
|
Post by ThomasW on Sept 23, 2010 11:59:35 GMT -7
The manifolds don't need to be 45" long, just long enough for the drivers to fit.
In addition to the driver holes being blocked you need a partition off the unused area of the manifold from the area where drives are operating
|
|
|
Post by wookus on Sept 24, 2010 4:43:05 GMT -7
I'm really very pleased with the sound of my system. The only testing I've been able to do is to use my SMS-1 to equalize the subs, so I can't give any real numbers other than to say that the response down to 20Hz is pretty flat. The room has no echo problems, and the bass seems very clear, though I have nothing to compare it to. The vocals in movies are very clear and easy to understand. All the bass trapping was a lot of work, and a lot of OC 703, but I think it's been worth it. There are a few things that led me to IB. First of all, I love the idea of diy projects. There may be no rational justification for some of them, but it's a lot of fun and it teaches me a lot. I've read many descriptions of peoples IB systems and I was drawn by the comments about the really low frequency response they seem to have. One poster described how loud enough volumes made his couch slide across his basement floor! That's impressive. I think what I'm looking for is the feel you can get from the really low frequencies even with the volume at moderate levels. I've pretty much settled on the Fi IB3 18's. The displacement of these drivers is incredible, and they are one of the drivers Thomas suggested. I wasn't sure how much power they should be fed, so I emailed Scott (ib@ficaraudio.com) and he responded promptly. He said "Normally about 600W per sub works well. While they can handle more at higher frequencies, at 550W free air at 20Hz, the subs reach their linear limit." Since Thomas, and others, recommend wiring the drivers for 4 Ohms or 8 Ohms, I decided I'd go with 8 Ohms to be kind to the amp. After lots of reading, I've narrowed my choice down to one of the following three: Behringer EP4000 - Two amps for four drivers - ~$350 per amp pro-audio.musiciansfriend.com/product/Behringer-EP4000-EUROPOWER-Power-Amp?sku=582002Carvin DCM 3800L - Two amps for four drivers - ~$700 per amp www.carvinguitars.com/products/single.php?product=DCM3800LPeavey CS 4080HZ - One amp for four drivers - $1300 per amp www.peavey.com/products/browse.cfm/action/detail/item/112596/CS®%204080HZ.cfmOne of the factors that drove me to choose these three was their listed frequency responses. All list their amps below the typical 20Hz that most manufacturers do. All three seem to have pretty much the same setup and I don't know if one would give better low bass sound than the others. It would seem, cost wise, that the Behringer would be the way to go. If money were not too much of a factor, is that what you'd do, Thomas? One last simple question for Thomas. I'd love to shorten the opening for the manifold. The reason I came up the 45" was spacing. I had figured on 3" space - 18"driver - 3"space - 18" driver - 3" space. I realize now that the two 3" spaces on the ends could be shortened because, structurally, those sections will be braced by the ends of the manifolds. What kind of spacing would you recommend, Thomas? I really appreciate all the feedback from everyone. This site is incredible. Have a great weekend, Dave
|
|
|
Post by ThomasW on Sept 24, 2010 7:49:35 GMT -7
I've auditioned several prosound amps and found little if any audible difference between them. (Note, I've not listened to any of the newish flea-weight all digital switching amps)
I've listened to an IB powered with hi-end 'Hi-Fi' amps like a Threshold, Krell, Pass Labs, Aragon, Ayre, etc., etc., there is an audible difference between those and the prosound units in a sub only A/B. (Generally speaking the sound is 'tighter' with better definition) I'm not so sure the differences would be audible when the system is running full-range. IMO, it's not cost efficient to use a multi-thousand $$$ hi-end amp with an IB unless one has financial situation similar to Warren Buffett.....
If the manifold has adequate stiffening braces the distance between drivers themselves and to the edges of the box can be decreased. The corners of the box are inherently stiff..
|
|
|
Post by wookus on Sept 25, 2010 4:51:35 GMT -7
One thing I just thought of. My placement of the manifolds will be limited by the spacing of the floor joists. Not a big deal, but...
An option I hadn't considered would be two cube manifolds (again, with two sides of each manifold plugged). The problem with that would be that since the joists are 16" on center, the manifold would have a 2 x 10 joist above it. Would that hurt the quality of the sound? If not, it would give me a little more flexibility in the placement of the manifolds. This is not a big deal, but it would make it possible to space them symmetrically (relative to the theater floor/room) which would look nicer and give exactly the same distance from each manifold to the listener.
Dave
|
|
|
Post by ThomasW on Sept 25, 2010 6:45:58 GMT -7
Cube or square manifolds are fine. That's what most people use since they require a smaller opening compared to a rectangular units
10" high joists are a non-issue
|
|
|
Post by wookus on Sept 25, 2010 6:58:28 GMT -7
Great! Thanks Thomas.
Would a cube measuring 20" per side on the inside be large enough? That would be 400 sq.in. compared to roughly 750 sq.in. total area of the four 18" drivers.
|
|
|
Post by FOH on Sept 25, 2010 12:32:03 GMT -7
............. I've listened to an IB powered with hi-end 'Hi-Fi' amps like a Threshold, Krell, Pass Labs, Aragon, Ayre, etc., etc., there is an audible difference between those and the prosound units in a sub only A/B. (Generally speaking the sound is 'tighter' with better definition) .............. Thomas, First, your work here is tremendous and I've leaned an incredible amount lurking and taking in as much as possible prior to my upcoming build. I like your no-nonsense approach, which is lost on some, but I certainly appreciate it. Currently being in the design stages myself for an IB, and kicking around amp and driver choices, I find your amplifier comments of particular interest. Having been involved in both live work and audio pursuits at home, I've often found different amps imparting different characteristics, or presentations of the recorded event. I too can generalize that "pro" amps are subjectively similar with the exception of LF control. I've found "audiophile" amps widely vary the presentation, and much more so compared to pro amps. I don't know if audiophile designers individually voice their work to a reference benchmark of their choosing, or to a theoretical spec, but differing outcomes are available market wide with the audiophile stuff...as we all know it varies from garbage to stunning transparency. Now with pro amps, I think there's less wiggle room in marketplace acceptance for different spectral signatures. Just as much of a "straight wire with gain" approach as they can, via different classes and trick power supplies, and engineer in and throw as much money as they can at LF control. Of the amps you listed, I've heard them all with the exception the Ayre. Also in my experience, those listed definitely possess some of the best LF control available. But, as you stated, the cost to benefit ratio is truly expensive especially if the benefit is masked when listened to with full range material. My question to you is what do you attribute the "tighter, with better definition" quality? I've read highly regarded opinions from various sources claiming that damping factor is of little importance...so what gives? Damping factor, according to a Crown white paper, as being the quantity assigned to the "ability of an amplifier to control loudspeaker motion". That ability is important, hell it's paramount. What about rise time or slew rate? Frequency response down towards DC? So control, speed, or extension..? All three most likely? I don't know as I've got no good measurement capabilities, I just listen. I've learned clearly how to know what I prefer. I've made a living at it. At any rate, if you could briefly explain what you attribute to the tightness and overall definition, I'd appreciate it. Also, I'll begin my own thread with some design choice questions as well. Great work, thank you.
|
|
|
Post by ThomasW on Sept 25, 2010 21:37:06 GMT -7
I'm not a student of amplifier design, I simply know what sounds best of the ones I've heard. In general I think a stiff power supply is mandatory. The best amp I've ever heard is the Boulder 2050 mono Block. Beyond that I leave amp criteria decisions to my friend JonMarsh. He was on the design team that created the Crown K1/2 series and functions as an amp design consultant when he has free time from his job as a Senior Power Apps engineer for Infineon Tech.
|
|
|
Post by ThomasW on Sept 25, 2010 21:50:18 GMT -7
Yes 20" on the inside will be fine..
|
|
|
Post by FOH on Sept 26, 2010 0:10:00 GMT -7
I'm not a student of amplifier design, I simply know what sounds best of the ones I've heard. In general I think a stiff power supply is mandatory. The best amp I've ever heard is the Boulder 2050 mono Block. Beyond that I leave amp criteria decisions to my friend JonMarsh. He was on the design team that created the Crown K1/2 series and functions as an amp design consultant when he has free time from his job as a Senior Power Apps engineer for Infineon Tech. I'm certainly not that knowledgeable in amp design, but like you, I would put that Boulder piece at the top of my wish list. I recently listed it in an amp wish list thread at AVS. I've never heard the amp, but it's a piece of work. Funny story about that amp; I've got a long background in temp power for concerts/tradeshows etc.., I'm working, and walking quickly down an aisle at a big Cedia show, I caught a glimpse of the huge "Pin and Sleeve" style power input connector on the back of that Boulder flagship amp. Seeing it physically made me stop in my tracks and turn into the booth and completely forgot where I was going. Had a wonderful conversation with the Boulder representatives and marveled at the craftsmanship and sheer mass of this thing....truly remarkable. They were not demo-ing the piece, just displaying. I'd love to hear it sometime, they're too expensive for me,...but they sure are nice. I too am struggling with amp and driver decisions for my IB. I'm guessing that when it's said and done and I'm all EQ'd and enjoying my new IB system, that it'll be so nice and relatively distortion free that I wont even care about the nuances that I'm considering right now. Maybe just a Fi18"/Behringer combo in multiples, and call it a day. However, I still consider the bigger drivers and amps. The Maelstrom-21 (why is there no builds w/this driver?). What about the RCF or B&C 21" drivers. Is the Fs too high to achieve optimum results with these? Is the accordion surround design really a problem? I know why the Fi/Behringer route is taken so often. It's the result of many projects, successful and otherwise, and it's an absolute known quantity. And with DIY, that's essential. There is enough variables the way it is, so known and tried and true is important. Besides, the value is tremedous for the combo as well. I'm just curious about some of the other bigger offerings. Has there been any IB build attempts with 21"s? Any info or links? Thank you
|
|