Purpose of flat response below 20Hz - Why does it matter? - Page 2

In my case, with the HT on a 2nd floor of wood frame, the entire floor ripples with the ULF bursts. It's a rather extraordinary experience your first time through it.

In a concrete basement, it's been best described by MKT, IMO. He says it's like being under water. The pressurization is much higher in a sealed room with concrete floor and walls because the transmission loss of the sound waves is up to 80% less compared to a wooden frame room.

Those are the 2 basic differences, but both experiences are unique in the history of recorded sound reproduction.

As far as the whole money spent thing goes, I've been around this and many forums over the past decade. I've seen people go through quite a few subwoofer upgrades, but they never seem to total the costs of depreciation and freight to let everyone know how much they've actually spent to arrive at where they are today.

It's always better to spend the money once at the git and have a system that handles the job and will last a lifetime than to slowly upgrade for years and still have a system that doesn't get the job done.

Just my 2 cents, FWIW.

Bosso

Agreed, my friend. I can't wait to see what you've had cookin' for a new system.

Bosso

Scott really just has an Acoustimass module stuck in those black cardboard boxes.

Lol!

That would be 18 Hz fior me. I don't have room for anything larger in physical size nor is my room sealed nor sealable.

Anyhow, your Terminator Salvation "comparison" is invalid. It is 100% obvious that you used two different SPL levels for the unfiltered and 20 Hz HP filter. The unfiltered chart has a much higher SPL levels as can easily be seen looking at the 20 to 40 Hz area.

Everyone knows that when making a comparison you must use the same SPL levels. Otherwise, people end up preferring the sound of the loudest sample. Since your spectrograms always use a microphone, you can't say that your levels match!

Terminator Salvation starting at 44 min 25 sec and ending at 45 min.

Upper part of chart uses 20 hz HP filter.

Lower part of chart is same scene full range.

Left side of chart is LFE channel alone.

Right side of chart is L, C and R channel together.

NOTE: If chart looks to small to you, use the IE zoom funtion to make the picture as large a you need.

You can talk the talk all that you want, but until you walk the walk I remain unconvinced. When I see you use a pair of "small" sealed cubes then you can talk about how size does not a matter!

Until MKT goes "small" on a permant basis, I remain unconvinced!

I'm getting sub 20 quite easily. Probably sub 10hz if one were to believe my mic.

I wouldn't personally call mine large, but then, they are relatively large for subs (same size as the Epik Empire). Way overkill for my 1700 cubed room, and could have likely gotten similar response from slightly larger boxes with dual MFW-15 woofers and an EP4000 vs dual opposed AV15H ($215 ea when I bough them) and a Marathon 5050. But I was perfectly comfortable with what I was spending, so didn't want to, potentially, sacrifice quality. For a larger room, I could just add another 2 of these (though if I needed 4, I would have likely went a less expensive route, i.e., amp-wise anyhow as what I have now as I stated is overkill).

For the record, I did end up running 2 dedicated 20 amp circuits up to my HT though, FWIW. Though I wouldn't call that a nuclear power plan, maybe one day if I do go with a dedicated HT.

Your assumption there is that it is in fact on the disk.

Do you have any examples of interesting program material - which is to say something that's not a plotless special effects wonder or an Erich Kunzel "sonic spectacular" disk that has ordinance going off to cover up how insipid the interpretation/playing is - that has much content below 16Hz?

Some of us couldn't care less what's in some Transformers or Hulk movie because, well, that kind of program material is not going to enter our homes.


It depends on the room, but it's entirely possible to get perceptually-meaningful performance down low with multiple relatively small and cheap sealed subs.

Thank you, DS-21. Im glad you came in to contribute.

You bring up a good point about this subject which is often neglected. The importance of getting 'x' amount of 'y' bass is purely at the discretion of the user. Not everyone likes to run demo disks and get the latest blockbuster just cuz things go boom so well. Not everyone likes the same content around here. Lol, I don't own a copy of Pulse or Flight of the Phoenix cuz, well... I didn't like the movies. I won't just get them cuz there is one scene with good bass and then go out and purely prioritize my bass system to hit 'x' amount of bass on 'y' scene just cuz it is there.

The flip side of the coin and which I agree with Bosso with, is that why would one arbitrarily cut off bass below a certain point? We all know why brand name manufactured subwoofers are compromised in certain areas because they have to. Usually a logistical thing from any angle. For example, a company could make a sub like mine but it would cost 4x the amount of material this is making it than to ship the damn thing and then nobody would want it anyway cuz its a huge, hard to move eyesore anyway. An eyesore that produces gargantuan bass but I digress...

One thing everyone seems to skip before they go insulting Bosso is that he never says you should compromise the rest of your bass system and to firstly prioritize single digit bass over everything else. Maybe some of you are selectively blind but I never see that in his posts. Just that it is easier to get very, very good <20hz bass for a lot less effort than 90% put into making a good bass system in the first place.

In the years I've been doing audio forum surfing (a good decade or so) I've seen countless and countless amounts of people buying one multi-thousand dollar subwoofer (yes, a single 'subwoofer') and then later on getting another and then later on getting another and then later getting another and so on and so on. All this money spent on the most minute increase, if you could even say its an increase, in bass SQ or SPL. A completely lateral move that gets that person nowhere.

How much do you think that system cost?

To the OP - Yes, bass below 20hz is awesome. I can attest to that. I have personal experience with bass below 20zh and it does feel different. It's a different sensation than purely <25hz bass. Is is so important that you should put 100% priority into getting said bass extention? No. Get a subwoofer system that works for you irt budget, SQ, size, volume level before you get all tangled up in achieving ultra low bass. Just don't let some people tell you that is useless cuz there is less of it out there or whatever their excuse is. It IS there so why not try and reproduce it.

The subject of this thread could also be applied to the "importance" of needed speakers that extend to 20,000hz or higher.

Yeah.

I think that having a sub that can dig to about the high teens is important. Then get the rest of the feel of lower frequencies with decent bass shakers, even put them in the floor if you want. Extremely similar feel, much more easily obtained.

Except for the under water sensation you get from single digits that you will never get from shakers.

Have you considered being in a pool with less people to avoid the single digit sensation, MK?

I was going to respond with "Pulse doesn't have much in the way of ULF content," but then I googled it and realized you were talking about a movie I'd never heard of and not the Pink Floyd concert CD.


Well, I'll tell you why I cut off the bass in the system I set up in the "modest multisub" thread. I had originally planned to highpass it at 16Hz, just to make sure any LF content in music would be reproduced. But there was a resonance excited in a floor-ceiling window below 20Hz, so after spending a little bit of time trying to fix it and being unable to do so without making things ugly, I set a steep highpass. Lesser of two evils, I think.

Truth be told, when I set up the revamped system in this place with closed box subs - next weekend, hopefully! - I'll probably filter it in the same place for the same reason, even though there will be more volume displacement. and a lot more power in the system.


In fairness, he did at one point. Just as I've come around to his POV on the subjective unimportance of box Q, he seems to have come around to mine on the subjective importance of low inductance.


I was going to respond with "Pulse doesn't have much in the way of ULF content," but then I googled it and realized you were talking about a movie I'd never heard of and not the Pink Floyd concert CD.


Well, I'll tell you why I cut off the bass in the system I set up in the "modest multisub" thread in the mid-20s. I had originally planned to highpass it at 16Hz, just to make sure any LF content in music would be reproduced. But there was a resonance excited in a floor-ceiling window below 20Hz, so after spending a little bit of time trying to fix it and being unable to do so without making things ugly, I set a steep highpass. Lesser of two evils, I think.


You already know this, but for anyone else reading, my impression is exactly the same. Instead of being smart and building towards a desired result, people just chase rainbows buying new stuff.

You mean the Geddes method? Geddes uses a single subwoofer corner located subwoofer to reproduce "down low". The balance of the so called subwoofers that Geddes uses are more in the MBM class.

Why is a Captivator arbitrarily cut off at a certain point?


http://forums.audioholics.com/forums...2&postcount=10

Nice build thread. You did a Bosso type of build.

Your system rolls off near 10 hz because of what, the power amplifier?

I got that underwater sensation yesterday, and I was only listening to a mono radio!

I'm not your movie/music critic. Screen your own source. This is a completely irrelevant point.


That's obvious. No one's arguing that point except you. Some of us couldn't care less what you prefer. Read the OP. It doesn't ask "...why does it NOT matter?".

Maybe you and J should start a thread.


No kidding? I appreciate the heads up. If you ask my neighbor, it's possible to get meaningful performance from the speaker that came installed inside the flat screen TV. You and JPC draw your line slightly north of that. I get it... Again, where's the relevance to the OP, or anything?

Bosso

Cool, you should use it in the theater

He does.

Bosso

Not sure actually, but also not certain that my measuring equipment is overly accurate once it gets below 15-20hz. Been meaning to try some new sweeps with increasing SPL levels but my MobilePre went Kaput the other day and I haven't had much time of late. Only get about 8 to 12 weekends of good weather up here, so Cottage time trumps HT time.

Hey Bosso, I have a question for you, check out my last statement about distortion and reply if you don't mind(f-20 thread)

You don't understand the method well.

All the subs have second-order rolloffs down low and enough no highpass filters, so all sum down low. There's nothing stopping a user so inclined from putting a shelf filter on any or every sub to EQ them to whatever LF response desired, even if it is nominally calibrated to a low level in the upper bass.


No, it's not. In fact, it's the only point that matters in this discussion.

What's the use of 5Hz extension when the program material one actually listens to doesn't have any content below 16Hz, or (as is usually the case) more than an octave above that?

You seem to think a system should be designed to an spec arbitrarily chosen by Dolby a decade and change ago, and point out a few mindless flicks that have ULF content to support that POV.

I'm saying one should start not from an irrelevant spec as the starting point, but rather start from what actually matters, the program material.

And yes, the spec is every bit as arbitrary as any other cutoff. How many studios do you think had the volume displacement to check for 3Hz signals when the spec was introduced? Do you think it was even one? I don't know for sure, admittedly, but knowing what was in use even by Lucas, etc., I highly doubt it.

And I don't know how to "screen my own source." Can you point me to a free OSX-native program that can analyze the spectral content of files encoded in Apple Lossless? If so, then I'd be interested in screening some songs. Otherwise, it's not remotely worth the effort, given that you have screened plenty of stuff and yet did not bother to counter my claim with measurements of even a single piece of program material fitting within the above-stated parameters showing content below16Hz.


That remark wasn't aimed at you, but JPC.

Are you asking why the Captivator, a ported sub, is ideally filtered just below it's tuning point? This is not arbitrary, but is a recommended practice for almost all ported subs.

Its all a choice. To correct some misconceptions, here are some simple points.

1. It takes a lot of displacement to get enough MEANINGFUL output below 15Hz. It does not have to be large boxes in room...I love someone posting someone else's DIY box trying to prove that is the only way to have bass, we could post 100 different designs for you, we can show sealed 18" cubed boxes with LMS5400s tucked nicely in the front corners of high end custom HTs but how about this subsystem....NO BOXES...27 liters of displacement, only 2000Watts needed for great bass down to 10Hz. This is better then 6 SVS PB13 subs and it extends lower then they do.....oh wait....it costs about the same as ONE PB13, less then JL Fathoms, less then Seatons submersives, less then the Captivator.....NO BRAINER there.

Find the subwoofer



2. No one cares what someone else likes or dislikes in terms of content, any post suggesting that everyone else should confirm to someone's choices of content is just silly.

3. Comercial subs roll off because of their design (driver designs, box designs, etc), no correlation to content requirements. Companies have to make a profit. The exponential $$$ increase for them in getting the lowest octave makes ZERO business sense.

4. Yes there is content below 20Hz, below 15Hz, below 10Hz....you can choose to want that content and you can choose not to want that content played back accurately in room. Choice is never actually something used as fact in a debate though

Conclusion.....I choose to make sure my system covers the most octaves. Once you have the best you simply never go back. All other systems are simply lacking, members of this very, very small club understand what Im talking about. The rest will never really get it.

It sounds like the answer is quite simple, and relatively obvious.

If you care about reproducing sub 20hz content encoded on discs (admittedly most of which are scenes in HT/Sci-fi movies), then for you, it matters.

If you don't, it doesn't.

Pick which of the above two you fall into, and design/build your system accordingly.

But, instead, this thread will go on and on ...

Who cares how much bass there is, when the front three speakers not only fail to be identical in design, height, and orientation, but also seem to be placed with the goal of expressly maximizing diffraction?

That's kinda what I mean about getting priorities straight.

Lotsa 10Hz, perhaps, but serious problems in the midband and treble.


I suspect that's a reference to my posts. As is usually the case when you read my writings, you utterly misinterpret the plain text of the words in front of you.

The unstated assumption in all of Bosso's posts is that people care deeply about reproduction of momentary special effects on program material that goes by names such as Hulk and Transformers, or cannon fire on crappy performances of the 1812 Beethoven's worst piece (Wellington's Victory).

For those who do, that's one thing. Such people should read Bosso closely and follow his advice, because not only is he talking directly to them, but also he knows what he's talking about.

My point is simply that if one does not particularly enjoy that specialized subset of program material and/or does not give high priority to its reproduction, designing a system primarily to reproduce that content is a misallocation of resources. ("Resources" here could be money, it could be space, it could be time, etc.)


That's not logical. Content requirements drives the market. After all, if people can't play content, what's the use of having it?

Besides, one can get copious ULF reproduction using commercial subs. Hsu, for instance, sells a package of four of their closed-box XBL 15's.

Or, in rooms with gain like MKTheater's, one could get scads of ULF from an Aura Whisper mounted in a soda bottle.


In everything? Can you show us a piece of music program material with content below 16Hz that conforms to the above requirements?


This coming from a guy who called me "elitist" recently.

Fact of the matter is, some of us have been in that club, and decided ultimately that, given the spectral content of actual program material enjoyed it wasn't worth the effort, expense, etc. to make ULF a priority. Now, if it happens to come about as a result of focusing on more important things, such as smoothing out the response in the upper bass, great. But it's not worth thinking about on its own.

I must be to young for this - where do you get this "mono"-radio cause I want one now