Subwoofers: Ported or sealed?

Ported for HT. Otherwise sealed, always.

@jaytor wrote:

Another option to consider is open baffle, if you have the room. I am really enjoying the bass from my open baffle subs, and prefer the bass quality compared to the sealed and ported subs I have had in the past. To me, it sounds much more natural than box subs - smooth, clean and dynamic, without pressurizing the room and without the boxy resonances that many box subs have.

Your open baffle bass/subs approach is an interesting alternative. I’ve heard a range of open baffle main speakers and generally liked them, but have never truly considered open baffle as a bass/subs tower option only. How high are you crossing them to the mains - indeed, how high can they be crossed?

Going by your descriptions they seem to share at least some characteristics of horn-loaded sub variants. Myself I’m using a pair of tapped horn subs (a Tom Danley patented design, though DIY’ers are allowed to roam freely making their own versions), fitted with 15" B&C pro woofers and tuned at approximately 23Hz. With a 20 cf. volume per enclosure they’re some bulky critters, but that’s the price when you need fairly deep extension in addition to higher sensitivity (97dB). They’re high-passed @20Hz (36dB/octave BW) because of the unloading of the woofer below tune, if mostly to alleviate any added distortion here.

Anyhow, few realize the smooth, effortless and immersive bass TH’s can produce, because hardly anyone have heard them in a home environment. It’s difficult to describe, but the bass of TH’s is just there in the room as this immersive presence; you don’t sense the bass being produced by cones with any effort, and as such it’s actually a rather "civil" though visceral bass reproduction compared to direct radiators (be they ported or not), that by comparison - to my ears - draw more attention to themselves. It would seem though in your case with the open baffle subs that they’re not a typical representative of direct radiators.

Some 5-6 years back I used a sealed 16" sub (SVS) and later added a 2nd one on loan to see how that panned out. Two of them no doubt was the preferable solution, but after quite some experimentation I still couldn’t them to gel in a satisfying manner with my then all-horn main speakers, and so I scrapped them both and went with the TH’s instead.

To say it made a difference is an understatement. The SVS’s went slightly deeper (infrasonic territory) and had a nice clean punch, but compared to the TH’s they simply felt compressed with bad layering, while lacking in central bass agility or "aliveness." The TH’s have a smoother, fuller, and slightly warmer imprinting with zero overhang - something that, conversely, marred the SVS’s - not to mention that the TH’s can be downright scary in their visceral-dynamic prowess and SPL capacity, and even so the B&C woofers barely move.

If given only the choice of sealed vs. ported, I’d go with a pair of large, higher efficiency ported subs (say, dual 18" or single 21" per cab) with a relatively low tune. Or, 21"-loaded 6th order bandpass designs with prodigious port area on one side of the cone, and short horn-loading on the other.

@phusis - I am currently crossing them over at around 180Hz. My main speakers are dipole line arrays which start to roll off around 200Hz, so this crossover point blends well. The sub towers with the plate amps I'm using won't play much higher than this. 

The drivers are made by Rythmik for GR-Research,  using a paper cone specifically optimized for open baffle. Each tower is driven with a Rythmik plate amp (HX800) which is built using two Hypex 400w amps, so the plate amp actually has two channels of output, each of which is connected to two drivers. These drivers have a second voice coil which is used as a servo feedback circuit to the amps. 

I don't think I've heard a tapped horn sub, but from your description I suspect the OB subs sound somewhat similar. They don't pressurize the room like a conventional sub - the bass is there in the room. For music from traditional instruments like double bass or kick drums, this sounds very natural. These instruments don't pressurize the room either. 

But if you are looking for that kick-in-the-chest sound, this type of sub is probably not for you. I wouldn't use them for home theater, for example, since most of the bass is from sound effects like explosions which you do want to pressurize the room. 

@jaytor --

It would be interesting to experiment with a pair of open baffle subs in a 2nd listening space and setup - they seem like a very capable design, not least as an overkill i.e.: über-sized option. 180Hz low-pass should be plenty enough to allow for a variety of design options above, like Danley’s Synergy horns or, like in your case, a line source.

Come to think it I listened to a pair of Quad ESL 63’s augmented I believe with a pair of open baffle fitted-to-the-Quad’s Gradient subs (dual 12" Peerless woofer per cab) back in the 90’s, and it was the best I ever heard the Quad’s. Indeed the pairing with the Gradient OB subs was excellent, and going by memory I’d favor that combo over the newer, more full range Quad iterations.

The TH’s are great for both music and movies, so yes, perhaps an OB solution wouldn’t offer the same versatile abilities here. Nonetheless they sound like an intriguing option.

@jaytor wrote: "[Open baffle subs] don’t pressurize the room like a conventional sub - the bass is there in the room. For music from traditional instruments like double bass or kick drums, this sounds very natural. These instruments don’t pressurize the room either.

"But if you are looking for that kick-in-the-chest sound, this type of sub is probably not for you."

Imo the advantage of an open-baffle, dipole sub is better room-interaction than monopole (omnidirectional) subs, resulting in smoother in-room bass. And smooth bass is "fast" bass, perceptually, because it is the in-room peaks which take longer to decay into inaudibility and therefore muddy up the bass. The result includes superb pitch definition in the bass region. But one trade-off is, good dipole bass doesn’t kick you in the chest like good monopole bass does. I say this as a long-time dealer for dipole speakers (SoundLabs).

Imo there is a technique which can combine in-room bass smoothness with kick-in-the-chest sound, and that is to use multiple monopole subs intelligently distributed. As the number of distributed bass sources increases, the in-room frequency response smoothness increases, and the variation in that frequency response from one location to another within the room decreases.

Disclaimer: I manufacture a distributed multisub system, BUT the concept can be implemented just by using multiple subs and spreading them around the room, and the subs do not have to match.

Imo the room’s effects in the bass region are roughly an order of magnitude more significant than the differences between comparably high-quality subs, so arguably HOW MANY subs you use (and how you use them) can matter more than WHICH sub(s) you use.

Duke