#81666 - 06/17/09 05:04 AM
Sealed vs Ported: Opine, Pls
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Desperado
Registered: 04/19/05
Posts: 361
Loc: Plano, TX
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So this is outlaw's first sealed enclosure subwoofer. I was sold on sealed since I picked Velodyne's F1500 from a lineup of 11 subs many years back, but I want to know...what does everyone think about the relative differences between sealed and ported? In my experience, sealed has always come off seeming to go deep without sacrificing accuracy, but with port tuning and hardware like the SMS-1 to help, that may no longer be the case.
What say you all?
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--Greg
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#81667 - 06/18/09 12:23 AM
Re: Sealed vs Ported: Opine, Pls
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Gunslinger
Registered: 11/23/08
Posts: 72
Loc: Spring Lake, Michigan
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I agree with you sluggo I really have always liked the sound of a sealed sub. I currently own the B&W ASW600 10" sub, which is a sealed enclosure and I find it to be much tighter bass and like you said very accurate. I think this new ESC-10 is going to sound great and deliver more power than most people have a use for, but I always like haveing as much power available as possible. I am excited to hear some oppinions of the ESC-10.
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Marantz SR57012,Panamax Power Conditioner, Rega P2 Turntable, Fronts - B&W 684 S3's, Center - B&W LCR600 S3, Surrounds - PSB Alpha, SVS SB4000 Sub woofer, LG 55" 4K LED Screen., SVS Speaker Cable.
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#81669 - 06/18/09 11:39 AM
Re: Sealed vs Ported: Opine, Pls
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Gunslinger
Registered: 02/23/09
Posts: 94
Loc: Waukesha, Wisconsin
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Originally posted by sluggo: So this is outlaw's first sealed enclosure subwoofer. I was sold on sealed since I picked Velodyne's F1500 from a lineup of 11 subs many years back, but I want to know...what does everyone think about the relative differences between sealed and ported? In my experience, sealed has always come off seeming to go deep without sacrificing accuracy, but with port tuning and hardware like the SMS-1 to help, that may no longer be the case.
What say you all? I've also always been a fan of sealed subs. In fact..I'm still using a pair of those Velodyne F1500r's that I bought in, I think, 1994. They still work and sound great.
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Main system: Integra dhc 9.9 Threshold SA/4e pure class A Emotiva XPA-1 (2), XPA-5 (2) Threshold S200's Thiel 3.6 main speakers (2)Velodyne F1500r subs Polk RTI28 surrounds B&W HTM center OPPO BDP-83 universal player Samsung HLT6187 led DLP
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#81670 - 06/18/09 02:33 PM
Re: Sealed vs Ported: Opine, Pls
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Gunslinger
Registered: 04/22/09
Posts: 47
Loc: Nassau County NY
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I've always thought that subs in ported enclosures have a tendency to be boomy and less accurate than sealed subs but I've never heard a ported sub controlled via the SMS-1. IMO for the $ I think one would be better off with a sealed sub with a good eq/amp vs. the cost of a quality ported sub, + an SMS-1 and the extra cables you would need.
I'd love to hear comparisons b/w the SVS SB 12+ vs the ECS-10. Both are very close in price & size. The amp on the ECS-10 looks like the one used in the Velodyne SPL Series. Nothing wrong with that just an observation. JD
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"What a man can imagine he may one day achieve." --Nancy Hale
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#81671 - 06/21/09 12:13 AM
Re: Sealed vs Ported: Opine, Pls
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Gunslinger
Registered: 04/28/07
Posts: 115
Loc: South Florida
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Sealed cabinet subwoofers will have a higher F3 than a ported one with the same driver. A sealed cabinet rolls off at 12db/octave while a ported one rolls off at 24db/octave. This means that while a ported cabinet may have a lower F3 than a sealed one, the sealed box might actually have a response that gets lower than the ported one, because of the less steep rolloff curve.
A sealed box will usually require more power to drive it than a vented box, indeed look at the power rating of the ECS10 vs Outlaw's other (vented) subwoofers.
A sealed box is less sensitive to the Theile-Small parameters of the driver, so it's easier to design. A ported box alignment is limited in freedom, while a sealed box can be tuned to specific Q's. BTW anybody know what the QT of the ECS10 box is?
The THX specification calls for a QT of .71 (Butterworth) which gives the lowest F3 without any overshoot (booming). (Hate to say it but the Outlaw bookshelf speaker and the Outlaw MTM speaker can't meet THX specifications because they are vented boxes. By design THX certified main speakers need to be sealed boxes with a QT of .71 and an F3 of 80hz to match the subwoofer crossover frequency.)
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#81672 - 06/21/09 07:16 AM
Re: Sealed vs Ported: Opine, Pls
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Gunslinger
Registered: 12/23/08
Posts: 51
Loc: XXX
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I have a few additional comments to add to kscharf's. The reason these small sealed subs typically have so much power is to bass boost their otherwise high F3 down to a level most aficionados expect to see. Another of my hobby interests is speaker building, and I've yet to find a 10" driver that provides an unassisted F3 under 40 Hz in a sealed box. Typically the unassisted F3 will be in the mid-40's at best. So, this type sub will need 12 dB of boost to achieve another octave lower performance. That's 16 times more power that does nothing to make the overall output louder. Dissipating all that extra power in the voice coil generates a lot of extra heat which leads to thermally-induced distortion. And then that small driver will need a longer excursion which adds to non-linearity distortion. The small box pleases a lot of customers, but it comes at a price. Of course nearly everything in life is one compromise or another, and you have to make the ones that suit you best.
A Linkwitz transform filter will compensate one Q design to another. This technique works for both ported and sealed designs to allow using a smaller than optimum box while still yielding a Q of 0.7 or lower. Rythmik Audio provides switch-selectable Q on their subs (0.5, 0.7 & 0.9) using Linkwitz transform.
The most common HT sub crossover implementation (concurring with the THX spec) rolls off the sub hi end at -24dB per octave while the main speakers' low-ends are rolled off at -12 dB per octave. This seems to expect main speakers with an F3 at the sub crossover frequency with a -12 dB per octave rolloff to provide equal effective high and low pass responses of 24 dB per octave. That requires sealed main speakers. I have not evaluated whether this makes an appreciable difference in SQ, but it did persuade me to switch to sealed design speakers when I upgraded recently. Seemed like one less compromise might be a good thing.
Incidentally, my upgrade did include dual sealed subs to eliminate another compromise. After some research, I decided to go with Rythmik Audio F15 servo subs. I'm sure there are better subs out there, but I'm thrilled with the F15 musical performance, and they're no slouch on HT either. I'll be keeping these awhile.
Bill
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#81673 - 06/21/09 05:23 PM
Re: Sealed vs Ported: Opine, Pls
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Gunslinger
Registered: 04/28/07
Posts: 115
Loc: South Florida
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It IS possible to get a sealed box subwoofer with an F3 below 40hz, but you're right it will take a driver larger than 10". Parts Express has several high end subwoofer drivers in their "reference series" and "Titanic" lines in the 12" and 15" sizes that will reach F3's in the 30hz region, even lower with a Linkwitz transform LPF. I guess you have seen this one, http://sound.westhost.com/project71.htm. Parts express even goes one better with a subwoofer designed for infinite baffle use. ( http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-455 ). This guy has a HUGE Vas of 8.73 ft3, along with an FS of 22hz. With a QTS of .59 this driver is designed to use your attic or basement as a sealed enclosure and should really rock the house. My dream design for a subwoofer was to take two of their 12" reference series drivers in an isobaric sealed box and use the Linkwitz transform LPF to get the F3 down to 20hz. Elliott has circuits for very high power amps on his site too. Of course by the time I factor in the price for all the parts, the wood for the box, and my time, the ECS-10 might begin to look inexpensive.
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#81674 - 06/23/09 03:12 AM
Re: Sealed vs Ported: Opine, Pls
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Gunslinger
Registered: 12/23/08
Posts: 51
Loc: XXX
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My remarks concerning sealed boxes with F3 below 40 Hz were for 10" drivers. 12" and larger drivers can pull that off, although the box size will be somewhat larger. My Rythmiks use Linkwitz transform and a small box for a 15" driver (20"^3) to reach three switch selectable F3's; 14, 20 & 28. These F3's are all below what I would expect for an unassisted sealed box of approximately 3 ft^3, although it's possible that 28 Hz does not require filtering. Essentially what's done for flat response to 14 or 20 is cut the higher frequencies until the filtered response is flat at whatever output the sub can muster at those low frequencies and then power boost the whole response curve.
Elemental Design claims their 18" sealed box woofer (roughly 22"^3) has an F3 of 20 Hz without assistance. I was a little skeptical of the claim seeing that the driver is derived from their mobile audio driver with an Fs of 24 Hz, but not knowing anything more about the driver or design, this could be an honest result. Parts Express 15" Reference sub can get sub 30 Hz in a 4-5 ft^3 box, but this is getting large for some people and was larger than I wanted. Isobaric can shrink the volume, but with extra drivers it gets pricey. As indicated, infinite baffle can yield some really low F3 numbers, but the volumes required are beyond what many can tolerate.
I also believe it's an Elliot Sound article that discusses how a sealed box couples energy into the room better than a ported box. I've certainly experienced that. I have a "T-Rex" audio track that is much more impressive with a sealed box woofer than a ported one even with the ported box having a lower F3. You could definitely hear T-Rex stomping through the forest with the ported woofer, but the sealed woofer provided more bass you could feel and shook the house more.
For anyone that places small size as a high priority, I think they'll find the ECS-10 to be a capable performer.
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#81675 - 06/23/09 12:29 PM
Re: Sealed vs Ported: Opine, Pls
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Gunslinger
Registered: 04/28/07
Posts: 115
Loc: South Florida
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"I have a "T-Rex" audio track that is much more impressive with a sealed box woofer than a ported one even with the ported box having a lower F3. You could definitely hear T-Rex stomping through the forest with the ported woofer, but the sealed woofer provided more bass you could feel and shook the house more."
I'm going to have to dig up my Jurassic Park DVD and try that.
My current subwoofer is an old 15" down firing passive unit sold by DAK many years ago. It has dual 6 ohm voice coils and a speaker level cross over. It's a sealed box measuring about 20"x20"x24" on the outside. Currently each VC is driven by it's own channel of a Niles Si275 amp (which results in almost 100W/channel into 6 ohms). Both channels of the Si275 are driven through a Y cable from the line level sub output of my Onkyo '702 receiver. The sub can really rumble.
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