Will two PB13Us generate useful infrasonics?

"My room is about 1800 ft^3"

"will two PB13Us generate useful infrasonics?"


YES but really the power of the PB13 design is only down to its tuning point, anything underneath is just gravy and definitely controlled by a high pass filter.

Now going from useful to insane infrasonics takes exponentially more displacement down low. Only sealed designs with large displacement will give anyone the ability to get meaningful single digit output because they do not have a sharp rolloff like ported designs.

If you can get sick room gain like MKTHeater's room. Your room seems like it might because of its size (what are the dimensions).

You can get single digit performance with comercial choices, it just costs more $$$ but 2 PB13s are close to $3500 shipped already, right? Have you considered a quad pack of HSU ULS-15s ?? or maybe a couple CHT 18.2s?

FWIW, Bosso is the expert, Im just one of his "lacky" students

Dual CHT 18.2's in that room might work. He could get three for a few hundred over dual Ultras if I'm not mistaken (plus shipping, though). I've never heard the CHT's, though.

EDIT: I may be wrong on the price of the CHT's... Yeah, I just looked. A little more expensive than that. Duals would be a cheap way to get a sealed design that MK is pleased with, though.

Yeah, DUAL 18.2 gives him 4 18" woofers, limited Xmax is the only down side but they are the ONLY dual 18" designs offered right now.

My room is 17-1800^3 and my single Seaton Submersive is showing response into the very low teens if not single digits, but then again I won't trust any measuring equip to faithfully measure that low... A (decent) single 18" will do nicely into the low teens as well, how much infrasonics you want even below there IMO is kinda silly but to each their own.... there is more then enough rumble down to 10hz, much less 15.... I personally don't really give a hoot about hitting content that low....

If you run the PB13U in Sealed mode, it can generate about 90 dB @ 10 Hz @ 2M GP without significant compression. Distortion is quite high at that SPL though, so I'd prefer to use 80 dB where THD is ~30 %, which is right about where the CEA-2010 limits would be (it pulled 87 dB @ 12.5 Hz which was Ilkka's lowest CEA-2010 test frequency).

In Sealed mode there is a high pass, but it doesn't take effect until <10 Hz (you can see this from Ilkka's graphs - there is no premature roll-off) and is basically there to protect against spurious infrasonic junk in the single digits.

A pair of them will add 6 dB @ 10 Hz in-room, even if they are not co-located, due to the length of the wavelength in question. This will pretty much be the case for all frequencies below the modal-pressure transition frequency in your 1800 ft^3 room, which is probably around 30 Hz.

In a perfect world, each near-field boundary will add 6 dB (but it's usually more like 4-5 dB with lossy walls), so if the subwoofer is corner loaded in 1/8 space with a quasi-nearfield ceiling boundary, expect maybe 10-12 dB of boundary reinforcement (which is not the same as room gain).

The acoustic transfer function (i.e., room gain) of your room depends on the layout and boundary integrity, but if the room is enclosed and pretty solidly contructed, 13-15 dB of room gain (relative to the modal drive level) at 10 Hz is entirely plausible (my own HT has 17 dB of gain at 10 Hz).

So depending on the listening position relative to the subwoofers, I wouldn't be surprised if you saw the following SPL at 2 meters from the subwoofers:

80 dB
+ 6 dB (duals)
+10 dB (conservative boundary gain estimate)
+13 dB (conservative room gain estimate)

109 dB (at least). This is usable SPL at the listening position at reasonable THD levels.

With that said, I feel 10 Hz output is highly overrated from a subjective perception standpoint. Response to at/near single digits can provide a palpable thickness in the air and foundation to the soundtrack. And if max SPL is not the first priority, then running your subs in Sealed mode can/will provide a satisfying playback experience.

With that said, if you want much more output and lower THD over the 13-40 Hz band, running the dual PB13U in the 16 Hz mode will provide a much more viscerable experience, without sacrificing much in the 10-13 Hz band.

The nice thing is that you have a choice with the PB13U - Sealed, 16 Hz, 20 Hz, and also three room gain corner frequency settings with two slope choices (six possible combinations) so you are sure to find the best combination for your particular application, room acoustics, and preferred level of slam/impact.

Why not try this... keep your present sub, and augment it with Buttkickers! It's extremely expensive to get to 10hz with subwoofers, and the results are often not worth the effort in terms of amount of useful content that low. The Buttkickers can handle all frequencies below 20hz, and give you the tactile infrasonics you seek at a fraction of the cost of multiple huge sealed subs. http://www.amazon.com/ButtKicker-BK-.../dp/B0006FK42S

Blah!!

Im disappointed if Im lacking it these days. The room compression from it is just insane. I can always tell what system does not do below 15Hz, there is definitely a different feeling. YMMV



I own 2 buttkickers that are mounted to my platform where my 4 HT chairs sit. IMO, there is a huge difference between them and what displacement does to a room. Definitely a cost factor involved if there isn't the DIY opportunity (Remember $2K gets you insane output in the DIY world with and IB installation)

I'd be curious to see the measurements of a single ULS-15 vs a single PB-13 in sealed mode given the significant box size and amp advantages of the PB-13.

As for the OP, having had a single PB13 in a 1700cubed room with a couple open doorways, it is very, very impressive. I also have significant room gain from 10hz or so up to 20hz. If you could fit two of those in the room, it would be very impressive.

Mind you, I'm sure 4 ULS's, or 2 of the CHT subs would as well (if you don't mind the aesthetics of them).

Well I did say I can surely perceive it, but it's more like icing on the cake when viewed in the larger perspective. Take care of 15-80 Hz first and worry about 7-14 Hz octave last. Since I have so much room gain, I'm a natural candidate to run sealed mode, and that's how my dual PB12-Ultra/2 are usually configured. Flat to ~10 Hz and plenty of output for my typical listening levels (-10 to -15 MV setting depending on the DVD). The novelty of 'reference level' playback wore-off years ago for me - I'm firmly in the 'comfortably loud' camp, with lots of dynamic headroom and low distortion and no artifacts.

Send me an email - I have a full data suite on that sub.

there is a member on these boards (counsil i think his name is) who has 4 PB13Us and 4 epik empires, if im not mistaken. is it safe to say he would be able to get into the single digits range easily and with useable output?

Here's some emperical: 2 PC13 Us in 16hz tune, 2800 cu/ft room, and I could feel the 10hz signal in 'Irene Irene' from BHD. That doesn't suck. I'm using the room gain comp, which is going to to reduce that a bit anyway.

Try the last 15 minutes or so of "How to Train Your Dragon" if you want to test the infrasonics. Just make sure whatever subs you have can in fact handle it, or at least know when to turn the volume down.

I'm not sure I'd want to run any of those speakers at 40hz/50hz x-over. If they are rated to 30hz, the lowest I'd cross them at is 60hz. Though with dual PB13's, 80hz is the lowest I'd go.

There is no question about it, the SVS products are killer, and their output numbers still hold up today as many enthusiasts use them for benchmarks to shoot at. The Ultra is one of the finest subs in the world.

Penn touched upon it, however it can't be overstated, a diy IB install would get you easily into the single digits for much less than your stated budget. The Cult of the Infinitely Baffled kindly welcomes anyone seeking to plunge the depths.

Before one adds in room gain or boundary gain, 110db@10hz@1m@225w can be had out of a combo of the EP4000, and four IB3-18s from Fi(Blueprint). That's well under the stroke limits of the driver, and 225w is used for an EP4000 8 ohm/channel output (2-4ohm 18s, in series). Regardless, these numbers are conservative. In room, at the listening position, levels of 115-120db@10hz wouldn't be unreasonable to expect depending on room and boundary gain specifics.

If high levels of 10hz is what you're after, here are two avenues to get there; Multiple small sealed, IB. An IB is a hard to miss target, then again so is small sealed. However, small sealed requires some measure of skill to make them aesthetically pleasing, and they require signal shaping and tons of power to overcome the small box. An IB on the other hand, gets to utilize all that free extension by not having to overcome the air spring, nor do they need gobs of power either. Additionally, an IB alignment doesn't need a big powerful motor assembly that accompanies the needs of a small sealed. An IB merely requires a modest magnet and vc, thereby keeping cost way down. An IB is excursion limited, whereby a small sealed is thermally limited.

Penn, Bosso's lackey, he's got both. A four driver IB array, and a small sealed with the finest LF driver in the world. He could answer your questions regarding specific differences. Back OT.....A quad array of HSU 15s would be killer. That's a very high quality driver. As your well aware, multiple sub locations within the room address modal distribution, thereby smoothing the overall response. So there is significant merit to multiple small sealed. Sounds like you have some time before this purchase. You're already ahead of the game by educating yourself and asking the right questions.



Good luck

Hi Dan,

Long post. Since I don't post much, I have to cram a lot into each post. But, I include pretty pictures and crazy stuff like the facts, so, at the very least, it's usually fun enough to wade through.



Hey, we all have our faults.

And, please don't buy into all of this "more visceral", "mid bass slam" Bah-Low-Knee.

Infrasonic content on soundtrack and hi-rez music discs is a very recent phenomenon in human history. It has become an extremely sophisticated art with many of the technical secrets being closely held by the top artists in the field.

Accurate playback of that content in one's home is even more recent. Like any new sensory experience, it is not best served by the initial blurting of some popular adjectives and quick subjective judgement from the vocal majority.

My take has always been that of the objective enthusiast. Keith Yates sums it up well for me:


Of course, he's only partially right. The "real estate" and "dough" comments are not so correct. I currently use less real estate than any of the subs that have been or will be mentioned in this thread. And, the cost is less than many enthusiasts spend on what they and their guests sit on while they watch a movie.

Over the past decade, I've spent more time studying the physics of infrasonic sound, comparing actual content to actual reproduction of that content in various rooms at the listening position, objectively through measurements and spectrographs and subjectively through listening sessions, than anyone.

Here is a recent exercise which compared a scene from HULK that has rather huge <10 Hz content. The subwoofers were configured to 3 different in-room responses; flat to 4 Hz, flat to 10 Hz and flat to 23 Hz. The methodology for asking unsuspecting listeners if they notice any difference and, if so, to describe the difference, will always be the subject of endless debate. Nevertheless, in my experiences with this sort of thing, based upon, if nothing else, the large number of sessions, source and audience diversity, they are conclusive.

The spectrograph lets one "see" what what presented:


In looking for accuracy in bandwidth, response linearity, compression, HD and SPL, the spectrograph, when coupled with a measurement rig that's accurate to 4 Hz, allows direct comparison of the direct analysis of the ones and zeroes from the DVD players SW output to what is presented by the subwoofers at the listening position with a high enough degree of accuracy. This scene with a gargantuan low frequency effect from the state-of-the-artist Randy Thom on the recent BluRay release of How To Train Your Dragon illustrates:


Now, you could drag the sub outside, run progressive sine sweeps until its tongue is hanging out, take the results and do some hypothetical math and post your opinion as to whether or not the sub is enough in some particular room. But, that's not going to be nearly as accurate an analysis as the above graph, so why waste the huge effort and virtual ink?

OPINIONS FOLLOWS:

I would say that the dual PB13 system in 1800 cubes should do a very good job to 10 Hz in 10 Hz ported mode. Below 10 Hz, I have no opinion because there is nothing available from the company on which to base an opinion.

Comparing the PB13 to the Chase stuff is a chuckle. SVS has been around since the beginning and this sub has been scrutinized from head to toe for years. Chase has been in and out of subwoofer business partnerships many times since I've been a member here, all of which have been short lived. And, despite the CHT people's claims of "a wealth of data', I have seen nothing to date to corroborate that. The PB13 is a very well designed and built subwoofer. The Chase stuff is the worst looking I have ever seen.

In fact, looking at all of the current commercially available subs, I would probably only recommend the SVS stuff or Seaton's SubMersive. Of course, my opinions in this matter are as biased as it gets. I view threads like "Audioholics Ultimate Subwoofer Shootout" as needing to be retitled to something like; "The Results Of Audioholics Special Olympics For Subwoofers".

The only system I can guarantee will get the job done in your room is the following, but that's mostly because there is no pertinent data for other systems and, quite frankly, I just don't care much about any other system:


I visit here and post regarding new and existing source material, how one might get the best from his existing sub, in-room and low frequency reproduction fact and theory and have rarely, if ever, engaged in which sub is the most-bestest one.

Bosso

^^^and where would that be available????

It's not, I think Bosso's simply saying "his system" is the only one he would "guarantee" would provide "infrasonics" below 10hz because empirical data for all the other subs discussed simply doesn't exist. I.e., no one can comment on sub 15/10hz "ish" frequency response for subs where the data isn't available to prove it.

Further, I don't know of many (any?) enthusiasts outside of Bosso that actually have the measuring equipment that would accurately measure below 15/20hz.

I would still maintain that Dan would be incredibly pleased with the output of dual PB13's in his room (assuming he does not want to try DIY, which I usually presume is the case for people posting in the non-DIY forum so I don't bother bringing it up), and provide him with the ability to "seal" them if he wanted to get a feel for what I'm guessing 3 to 4 ULS-15's would provide. Save for the added smoothing in the frequency response the additional subs would provide benefit-wise.

I have almost all the designs.

IB array with 4 Q18s.
Two 11 cuft ported TC2000 15" subs
two LMS5400 sealed 3.5cuft designs + 4000Watts each.

I have 2 PRs + AV15X but I never built the box instead I used the AV15X woofers as bass bins making my mains full range.

I will be working on a 12Hz tuned monster horn design this year when I rebuild my HT room.

Your point about the quad ULS-15 system is a good one but I will go more generic then that. I think a quad pack of any propular subwoofer choice is the best way to get output and smooth in room response.

There is no replacement for displacement, that is not just a nice catch phrase its just the absolute truth about subwoofer low frequency performance add to that Toole, etc go to great lengths in explaining how adding subs will naturally smooth out the response curve.

If people want to know if they can have low end performance they simply have to findout the liters of displacement your sub system is putting out. My IB system does almost 27liters of displacement, as a reference point One PB13 does under 5 liters.

This does not mean the PB13 is a bad choice, its a great sub. It was the first comercial sub to really dig deep and go loud (with low distortion). Ilkka and the experts online found it be very impressive and again TWO PB13s in your room are going to be pretty damn good.

Ok Penn I am having a brain fart this morning and you have piqued my interest. How do you determine total liters of displacement?

Displacement p-p (liters) = 2 * surface Area (cm^2) * xmax (mm) .

Thank you sir. I need one more piece of clairifcation and that would be how do you measure the surface area of the cone? I feel like such a dufus this morning. Or can that info be found somewhere if you know which driver is being used? Also doesn't the enclosure contribute to the equation?

Curious, has the xmax been published for the PB13 driver or are you just estimating (i.e., a few mm here or there won't make a big diff in the calc)? I don't recall seeing it (but haven't looked at the specs in ages!).