Sealed Vs. Ported

antspool

What is everyones opinion on a sealed and ported subwoofer enclosures for your ht? Any obvious drawbacks to either?

jcaut

Here's my thoughts:

For a small sub, a sealed enclosure should be able to acheive lower frequency response than a ported design. That, and, at least in theory, sealed enclosures should offer tighter bass with better transient response than a ported design of similar size.
On the other hand, a ported design will almost always produce louder bass, due to the higher efficiency of the design. And large-volume designs can produce very loud, very low, bass.

Ported designs have come a long way in the last ten years or so, and the differences aren't so great anymore. You could generalize that a ported sub would be better for movies and a sealed sub would be better for music, but there are some very musical ported subs available. The best compromise may be to use a passive radiator design.

The only sealed sub I've personally had any experience with was a DIY job that I built. And out of fairly cheap parts, at that. It seemed to go pretty low, but was terribly ineffiecient.

Jason

DarqueKnight

For a HT, tightness and accuracy are not as important as they would be in a musical application. I typically don't like ported designs for music at all, although, as Jason said, the differences aren't as great any more.

If you want to go down to a clean 20 Hz with any kind of efficiency and volume, you would need an impractically large sealed enclosure. In my home theater, I use SDA 1C's (a sealed passive radiator design) as fronts and two SVS CS Ultra subwoofers (ported design). The SVS's blend seamlessly with the 1C's. I don't even have to do a bass volume readjustment when I switch between HT and music modes.:cool:

dean/klipschead

Sealed designs are certainly more musical sounding in my book and they are my personal preference - however, to get one that does HT good requires a good 15" or 18" driver and a crankin amp. Kind of pricey. Something like an Velodyne HGS 18 would be nice. Got $3K? I sure don't.

Something interesting though is that a driver in a acoustic suspension sealed design has to move 4 times farther than a driver in a ported design (at any given frequency) - so more intermodulation distortion generally speaking. OTOH - there is nothing worse sounding than a cheap, ported sub.

The passive radiator designs are a nice compromise as Jacaut says. Take your pick - everyone is making them.

I think it really depends on price points. If you got the dough get the Velodyne HGS 18. Nice, tight, powerful, tuneful bass. Got 1/2 that amount than go SVS Ultra. Down around $1000 the choices are endless. SVS will always go louder and cleaner than anyone else at any price point - but then you got to look at them black trash cans sitting in your living room.

I do think if you do more music than HT than Velodyne is the way to go. Sealed designs are just plain more musical. They also seem to have better 'pace'.

antspool

Hey, thanks for the input everyone. I think I'm gonna go for the sealed, just so that I have the music covered. Plus I want to design my own enclosure, so the port would be a little more difficult to do on my own. I'll let everyone know how it turns out (if I'm lucky, everyone will hear it lol)

Thanks again.

jcaut

Are you going to build one from scratch, or buy a kit? There was some discussion about a kit from Partsexpress a while back. I think Chris built one...

If you're going to start from scratch, get a good speaker design book (if you don't already have one), choose the driver carefully, and use good quality materials in the construction of the box. Think big, long-throw driver, large internal volume, and lots of amp power.

Jason

juice21

definitely keep us posted with your progress. it will be interesting to hear your results...

dean/klipschead

yep - lot's of power

I wouldn't use one of those plate amps if I was doing DIY

get yourself a used Adcom 555 off of AudiogoN and bridge it for 600 watts

all you would need then is a little outboard low pass filter

Paradigm makes a pretty nice one for $80

rskarvan

I really think that ported designs compromise the sound of a loudspeaker. The passive radiator in vintage Polk's is really a nice compromise. If you want to increase the spl/effeciency of a speaker... no doubt, ports will do that. But, its always at the expense of "tightness" of sound.

Sealed speaker enclosures are always considerably larger.
Its no wonder that Polk (and others) push ported designs due to their lower manufacturing cost. Its just a shame that the public doesn't seem to appreciate optimum sound.

Also, I think 2-way designs are a compromise. A good three way speaker is optimum.

Common drivers (6-1/2"ers) are also another compromise to minimize manufacturing cost.

Lets face it folks... the speaker manufacturer's mostly pass to us
less-than-optimum designs. Sigh.

DarqueKnight

A word of caution about the bridged Adcom 555: The sound seems to take a "glazed over" quality in bridged mode. I already had a couple of GFA-555 MkII amps and I was considering using them in bridged mode with my SVS CS Ultras (4 ohm load). The 555 MkII is rated at 850 watts into 4 ohms. The bass was not as "fluid" and detailed as it was with the lower powered GFA-5500. I finally settled on using GFA-565 monoblock amps (450 watts into 4 ohms).

I also tried the 555 Mk II's in bridged mode with my SDA 1.2TL's (had to connect the grounds of both amps together). The bass took on a slightly "boomy" quality and the highs and midrange seemed compressed.

There are some other reviews at Audioreview.com that mention a degradation in this amp's sonic qualities when it is bridged.

dean/klipschead

good info - i wasn't aware of that

i was kind of thinking that since they can be picked up for around $300 or so - one would make a good dedicated sub amp

600 watts of anything else gets expensive - $300 is bad enough

antspool

Yes, I'm starting from scratch. Already have the drivers (2 MTX 12" subs), would love to go polk but once I get the LSI's, money becomes a factor, so have to improvise with on hand parts for awhile. And I would definetly rather cut back on the sub than sacrafice the LS's. I'm thinking of going to separate sealed enclosures. Maybe one sealed and one ported (best of both worlds, hmmmmmmmm). I got my hands on an enclosure building program. Haven't had a chance to check it out yet though.

Thanks again for all the input, when your coffee cup falls off your table, you can blame me. Either that, or when you see the smoke in the distance, you know something went wrong.........

MIKLSAN

Dean/All,
He would not necessarily need a low pass filter if he was using the sub with a Dolby Digital receiver/processor. The sub out is already filtered. Most DIYs are getting away without an outboard XO. Regardless of whatever design you choose, I hope you enjoy building your own sub and tweaking. DIY can be fun!

dean/klipschead

that's right - i forgot about that

oh well - us two channel guys only have 2 dimensional thinking

gidrah

Building a horn sub enclosure. There's a cold air return (gravity furnace) slightly off-center to where I'm going to build and in-wall entertainment center. Now if I can just sneek a couple 18"ers past the wife.

Best of all worlds.

MIKLSAN

gidrah,
You should check out some of the DIY Infinite Baffle subs that have been done. There are a number of sites and forums devoted to this type of setup. Just slap a dozen 12 inchers in your basement or attic and vent them through into the room. Presto! 120dB @ 20Hz with no large unsightly enclosure in the room! Bet the wife would love that!

You want scary? Check it out: http://home.att.net/~kloneaudio/page21.html

gidrah

Where's my tape measure.

dougg

Anyone like the sunfire true sub? I was very impressed with it. I rtested it on a freq generator in my office started at 40hz and lowered it to about 15hz. At 18hz it started jumping 2-3inchs off on the floor! One powerful 'little' sub!


http://www.sunfire.com


Doug