Purpose of flat response below 20Hz - Why does it matter? - Page 3

Did the wife give you permission to use your system again? Last I heard you have not used the system for a few years for family reasons!

I was talking about the design choice, not any optional electronic filtering.


As far as the HP filter is concerned, maybe one is required or desired or maybe not.

While we're here and penngray brought it to the table, what are your reasons for not liking the IB approach, bosso (if this is true and I'm remembering correctly)?

And JP, I don't understand the recommendation to run the Cap without a filter, though I think Jeff probably OK'd this a way to save money (?) per customer persistence since the danger for damage was minuscule with the power provided- not as a way to obtain usable output below tune.

That said, I've seen a lot of these passive Cap's run without EQ and yet hear things like the above: "Bass extension is deep"- but the passive unit is 9dB down at 20Hz and 13dB down in the 15Hz tune.

Now, if they have 9-13dB of gain at 20Hz to combat the need for EQ, then why the heck are they using a ported unit in that room?

If you are amp-limited, the woofer is less likely to be damaged by a lack of HP protection, but you can still waste power by attempting to drive the sub below it's tuning if there is such content present. That's why ideally you would HP even if you could get by without it. Jeff utilizes HP in the amped Captivators.

Thank you, Penn. I guess you just got to experience it and if you like it, you know you want it. I know I do.

Good luck to the OP. Hope he has a good BS filter.



Oh, your sub is in the ceiling. Gosh!

I understand the theory. My system (not a Captivator) has a 15 Hz HP filter in the subwoofer circuit.


My point was the Captivator is not flat to DC and some people do not mind!

Fine for the Southern boys and their McMansions. Too much heat loss for use up North!

Pfft. Well I guess that settles it now, doesn't it.


That's a shame.

The Captivator like all ported systems is a compromise. Presumably the buyer is willing to trade off the frequencies below tuning for the sake of much higher sensitivity and lower distortion at and slightly above tuning. I love ported subs like the Captivator and the PB13 in my huge open room, but if I had a smaller, closed room, I'd go for sealed subs and shoot for a flat response to single digits.

Getting back to the topic: "Purpose of flat response below 20Hz - Why does it matter?"


Let's listen to a few scenes with high level ULF. Give me your "subjective" take on the "lightning stike" scene in WOTW. Give me the time stamps of the 5 "best sounding/feeling" LFE effects starting outside the house and ending with the last stike when they are inside the room.

Your subwoofers are more than capable for this test. Just note down how loud you are playing your system if you chose to make a subjective comment on this.

Note that they are not underwater in this scene. That is later on in the movie!

Your not a manly man!

(LOL) You only say that because you haven't seen me naked!

I don't get an 'underwater' sensation during this scene. At least, that's not how I would describe it. Bosso and Josh Ricci have described some of this super low bass as having a "shuddering" like effect and that is kind of how I would describe it. Anytime I watch a movie and am not suspecting that kind of deep stuff I sit back and sincerly have "woah" moment. First time I saw the new Star Trek movie at home I got that. Right in the beginning when that ship emerges from the blackhole. Again most recently in Tron Legacy when Sam gets transported from the real world to the virtual world. My friend that watched the movie with me said he thought some stuff was deep (mostly the 30hz stuff) but mentioned that the only time I said "woah" was during that moment earlier in the movie. Which just so happens to have some good stuff to around 10hz or so. Should I go grab the bass chart?

Anyway. I wouldn't mind taking some readings, myself but I am sans SPL meter at the moment. I sold it to another forum member that needed it much more than I do anymore.

No SPL readings are required. Just something ballpark like DTS played back at say -5 dB from calibrated reference level. Things sound different at full reference level than they sound at more typical listening levels.

I am asking for your take on the listening experience. Subjective like in how does it sound/feel. If sub 20 Hz content is that important, you should be able to pick it out without the use of a spectrogram.

The use of the word you is more or less a generic you, so don't take any of this personal.

Aha, another Weinergate coming up soon!

1) "...point out a few mindless flicks..." How about a few thousand movies that aren't screened by your personal biases?

2) If you think the spec is "arbitrary" and "irrelevant", that's fine, but please do your homework and point me to a Dolby representative who will corroborate that opinion. I asked this question of Tom Holman 10 years ago. His answer was not "It's arbitrary and irrelevant".

3) Every recording enthusiast in the country has the ability to visually monitor spectral content in his/her home studio, let alone a state of the art movie soundtrack studio console. Your bias is exposed by your thinking that these top sound design artists are too ignorant to know what a spectral analyzer is, what a high pass filter is or what content is in the effects they create when they create them. It's an absurd allegation that persists for some baffling reason. I wish you'd stop regurgitating it.

4) You can screen your own source simply by watching your sealed subs drivers. After building my first sealed sub with L/T inserted, I was playing Sting's "Big Lie, Small World". I noticed the drivers moving in a below 20 Hz manner at about 1 minute into the song. I asked about this in forums and was told it was something wrong with my playback system. It wasn't until years later, when I got SL hooked up, that I saw the content of the sound. Notice the difference at around 1 minute in.



Is the album "mindless" and "irrelevant"? Not for me to say. How many recordings have such content? I have no clue, but I know this: if they do, my system will reproduce it. I continue to marvel at the logic that concludes that that's a bad thing.

I mean, come on... point you to interesting source? It's all interesting to me. Life in your house sounds pretty boring, so how would I have any idea what recorded source interests you?

Bosso

I'm not sure if you missed it but I've been pretty darn clear about my feelings about <20hz content and how it makes me feel. Yes, now that I have been living with a subwoofer system that is capable of very high SPL down to 10hz for a few years now, I CAN easily detect that kind of deep bass without a spectragraph telling me. Not that I don't like seeing them and confirming my impressions.

If you were to read allll the way thru the bass chart thread, you will see many many posts from me pretty much laying out how much (or how good) bass was in a certain movie that may not have been plotted yet and my observations line right up with the graphs made from other users.

I had watched Star Trek, for example, and detected that deep part in the beginning (which, btw has a lot of info down to 10hz or lower) and was like, "woah" or maybe I didn't say that out loud but if you saw my face, my eye were prolly bulging out and I only make that kind of face when I feel something really deep. Below 20hz. It's a different sensation than 20-30hz which is a different but totally awesome bass range in itself.

Look. I think 25hz and higher bass IS the priority but don't just throw out the capability of <25hz just because there isn't enough content as per anyones particular taste. If having such capability does NOT affect or compromise the >25hz bass then I don't see why it would be an issue being able to actually reproduce super deep bass. THAT I just don't get... but I'm weird and forever alone. Ha! Ugh.

I want to play!! During WOTW lightning strikes what happens is you get pressure and a quick bass wave(I like saying pulse wave but just choice). It is not loud at all, just happens. The most impressive bass scenes to me are like FOTP when the plane rolls over. Much much louder but it happens from 20-30hz which is the sweet spot. It is nice to have all the bass for the one reason you know that you are not missing anything. Having it flat is one thing, having it loud enough so you still get it is another, they both work. I would never HP this stuff out but with ported subs the distortion might be to high. I can tell you how many times people are more WOWED by loud 20-30hz bass than the low stuff.

BTW, what I mean by underwater is just play the scene from The New Daughter in the cave, with a flat sealed system and sealed room you will understand.

Very good post, Bosso. Thank you. Agree on all points but especially hit home run with points 3 and 4 there.

It's personal priorities, folks and I wish we could all come to a conclusion on at least that.

Sigh!!! What is with the silly personal questions???....... I proved that your picture of a big ported DIY sub was grossly misleading and you take this approach. I have 2 little girls, now 2 and 4... The IB system was built 6 years ago...you do the math and it was not a permission thing (it was a logical thing), it was simply an understanding of what having a family and bedtime means something to some of us. There is no need for loud movies at night in the family room IB or not, any good bass system is going to wake up babies


If you want to play this personal game you should post that you also know I have a custom HT room, with twin sealed LMS5400s and 8000Watts + AV15X sealed subs to smooth out the in room response. No reason to use the family room when I have another room that is 100% custom HT room and its at the other end of the house > 60 feet away from the girls bedrooms = a lot less bass = they stay sleeping

If you are going to have comments about other systems (including personal OT that is meaningless to the discussion) then I would hope that you post pictures of your setup. It only seems fair considering what you posted already about others.

Your reference is this.....
"I have the EP 4000 in bridged mode without any low cut filter ( per Jeff )"

You do realize that is talking about the 30Hz low cut filter switch on the EP itself and nothing to do with an HPF requirements the Cap needs

Which LFE effect is better? The outside lighting strikes or the inside lightning strikes?

While we are at it, what SPL levels are we talking about? "Reference" playback level?

Your measurement "microphone" is hardly accurate, so I am not sure what "flat" measures in your case. Note that I don't trust my low frequency measurements either (RS Digital SPL meter C scale as microphone).







My version of FOTP has no decent bass!

Amyhow, you are not going to get ULF at useful SPL levels without a decent amount of power and drivers and an appropraite listening room.

Sure I could go lower in my own room. I just have to use 4 times the drivers and 4 times the power for every lower octave that I want to hit.

Oh... In my room, it is the shots from the inside that are 'better' but they are also a lot louder too, iirc.

Did you not have your subs on during FotP? Seriously, I think that is your problem, JPC.



Ummm... not exactly.

Agreed there. The problem is that your conditional often does not hold. People chase the deep stuff passionately, and ignore stuff that matters more. Not you and not Bosso, mind. But plenty of people.

The "THT" boomlet was, IMO, a reaction to that. People who had been chasing deep stuff all of a sudden discovered that dynamics on actually extant program material was more fun.


Nah. I only care about program material that fits in my personal biases.

I'd expect others do to as well, the only difference being what kind of program material that fits their personal biases.

Of all of the movies I've seen mentioned here for ULF content, I've seen (and own) exactly one of them, Black Hawk Down.


Well then, what was his answer? (Not that anyone would have actually expected his to answer that it was arbitrary, even if that was the actual case, of course.)


Why is it so absurd?

If various remasters of DSOTM can have parts erroneously out of phase, etc., then it's entirely possible some ULF could inadvertently slip in to a movie master. (Is that the case now? Probably not. Having the ULF content now makes people talk about a movie on forums and such, and probably increases sales.) We're talking about some throwaway flick vs. the third best-selling album of all time here!


Interesting, as "Brand New Day" is an album I own.

I can't "watch my sealed subs' drivers," however. I prefer my subwoofers to be heard/felt and not seen so I cannot simply watch them move.

Also, it does not follow from its mere existence that the sub 10Hz content (3.something Hz if I'm reading your graph right) is intentional. Especially in a recording that (if memory serves) is from the late 1990s, when few music lovers even owned subwoofers. What does it correspond to, musically?


Yes. I will change my mind about sub-16Hz content if someone can point me to useful recorded musical information down lower than that. You're a bit of the way there, with the Sting track. Now, if you can correlate that to music, you'll be there.

But if said content is just explosions and thunderbolts and the like...not worth it to me, may be to others.

Well said, DS-21. Not sure if I count cuz I was chasing 10hz a few years ago when I designed my LLT's. Hey. We learn through experience.

Though in doing so, they inspired me to build better speakers (the entire frequency range YAY! not just bass. ) but only mostly because my mains just can't keep up with the subs.

lmao....nice attack Its a picture from 6 years ago....the front speakers have changed but still have to find compromising space for them.

Okay, lets review the goals and the constraints of the project.

1. I wanted bass in a 35x50x12 room. I wanted a zero foot print, can not have subs on the floor and have the room look like Im still in college

2. Im not looking for ultimate system there because the room is a family room meant for fun, hosting events (football and 40 people). I wanted bass during movies with the footprint.

3. Yes, absolutely some issues will exist but I still have high performance bass and was happy when listening to music, movie or event.

4. Its a family room, it hosts parties, it allows for families/kids to come over for pool parties (the back doors go to the pool). You honestly think its a room where speakers and subs can be on the floor at all?? Its not a bachelor pad, its not a student living space. It has to have style and speakers HAVE TO BE OUT OF THE WAY because the real world does not think they are remotely cool. I have the custom room for all things cool in audio (just for me)


Yes, I 100% agree there are compromise involved with that but 99.9% of all systems posted online or owned still do not have the bass that room has period...I do not know of an individual that does not go "HOLY CRAP" when enjoying it so while your points have meaning online. The real world says its an incredible experience period.


I do have a custom HT room too...you know this (like JPC you guys look for holes and attack) and in that room I can build/design, measure until prefection exist if I choose too.

You still miss the point of the IB picture. It shows that people can obtain the lowest octave without large boxes, without huge $$$. That was the point, JPC tried to paint ULF systems as BIG boxes when that just is not true. It was not a point to say "here is the best overall system". If someone wants the best they still have to add midbass subs but that is a given once education happens.




No one is making ULF a priority OVER other ranges. Some of us just want it all. Again its a choice, you are posting that people should not have that choice and they should follow you only...that does not make sense to me.

If its okay with you, I would like my rooms to have 10Hz performance...is that okay??


The only truth here is that.

1. There is content below 15Hz.
2. There are many ways to obtain performance at the lowest octave and some designs cost the same as one PB13.

If people care about that then they can bypass you and JPC and ask Bosso, myself or many others that can offer solutions if they want them.



btw, Feel free to post pictures of your perfect family room so I can learn from them.

Whether it was flat or not does not matter, because it was not that far off either way. I know what you are saying and the outside strikes are more impressive than the inside strikes but many don't get anything for the inside strikes but it does create waves and pressure. There are some inside scenes that are 15hz to 20hz as well.

We are okay with it not being worth it to you. Is it okay for those explosions and thunderbolts to be worth it to a few of us??

This is 100% choice type of arguement....the best answer is to let everyone choose what they like. This is about audio science so after they choose what the want, we can explain to them how to maximize the performance. No one should ever post opinion on what content is right or wrong.

That must be the Jimmy Stewart version. Great classic movie!

I want accurate movie playback, what does that mean? It means that when there is a thunder storm it needs to sound and feel like a real one at reference levels. I just think it is fun for the effects to be real like that, it scares the heck out of people like the real thing.