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Author Topic: 146.8db  (Read 1746 times)

Aaron Maurer

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146.8db
« on: March 23, 2020, 06:27:43 pm »

I will let the experts tell me if the numbers could be real?  I am not educated enough to confirm or deny if itís possible. What say you?

https://m.youtube.com/watch?v=2sNqwZGHtzo
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Luke Geis

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Re: 146.8db
« Reply #1 on: March 23, 2020, 07:02:52 pm »

Plausible, yes. The subs in each instance are essentially corner loaded or 1/4 space, heck even 1/8th space loaded, so you get loys of free energy. Now the SPL recorded was probably in the lower frequencies which doesn't have much value to me. The tops/mains would be the limitation with likely a 135db ish peak potential. How good it sounds at that level is up for serious debate. The fact that ceiling panels were falling down leaves me with the impression that it was a room mode, rattle fest. I don't GAF how loud it gets, if I hear rattling and oddball sounds from the space, it sounds like ass. No to mention, that there is no reason to even bother bragging about getting that loud in such a small space anyway, you can't listen to anything at that level and enjoy it, so the metric for it is pointless. I know that JTR is a good company and they make good stuff mostly aimed at home theater, but I wouldn't be bragging about the SPL. The quality of sound would be more my flavor.
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Steve-White

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Re: 146.8db
« Reply #2 on: March 30, 2020, 12:23:53 am »

No way.

The tops couldn't get anywhere near that and I doubt seriously of the bottom end would either.
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Chris Grimshaw

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Re: 146.8db
« Reply #3 on: March 30, 2020, 07:39:39 am »

I think it's entirely possible that the system shown put up 146dB in a room that small. I'd say it needs to be carefully chosen content (ie, the right mix of bass, mids and high so that each component hits the limiters at the same time), carefully chosen mic position, all speakers firing (including surrounds) etc.

That said, I wouldn't want to be in the room when that system was going full-bore. Too loud. I enjoy movies with a pair of 8" 2-way speakers - they get low enough into the bass, and loud enough to hear everything clearly.
I don't want to worry about the structural integrity of the house while I'm watching a film. I'm sure if I brought some of the PA subs in that I could probably knock many things off many shelves, but I'd only have to tidy everything up again. What's the point?

Chris
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John Halliburton

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Re: 146.8db
« Reply #4 on: March 30, 2020, 08:09:34 am »

I think it's entirely possible that the system shown put up 146dB in a room that small. I'd say it needs to be carefully chosen content (ie, the right mix of bass, mids and high so that each component hits the limiters at the same time), carefully chosen mic position, all speakers firing (including surrounds) etc.

That said, I wouldn't want to be in the room when that system was going full-bore. Too loud. I enjoy movies with a pair of 8" 2-way speakers - they get low enough into the bass, and loud enough to hear everything clearly.
I don't want to worry about the structural integrity of the house while I'm watching a film. I'm sure if I brought some of the PA subs in that I could probably knock many things off many shelves, but I'd only have to tidy everything up again. What's the point?

Chris

What the home theater guys get is clean, extension, and dynamic sound out of their systems, which many feel is paramount in a really good surround sound system.  Jeff delivers the goods, I've known him for almost twenty years now, and used his pro speakers as well as been at listening sessions.  One of the coolest was his demo room at AXPONA last year where he set up a good sized dolby ATMOS based surround system and a top shelf projection set up.

That was one of the best theater experiences I've witnessed.

Best regards,

John
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Ivan Beaver

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Re: 146.8db
« Reply #5 on: March 30, 2020, 11:19:39 am »

I will let the experts tell me if the numbers could be real?  I am not educated enough to confirm or deny if itís possible. What say you?

https://m.youtube.com/watch?v=2sNqwZGHtzo
That's not really all that loud for a "good" home theater. In a small space you get a good bit of room gain/pressurization.
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Craig Hauber

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Re: 146.8db
« Reply #6 on: March 30, 2020, 11:36:02 am »

I will let the experts tell me if the numbers could be real?  I am not educated enough to confirm or deny if itís possible. What say you?

https://m.youtube.com/watch?v=2sNqwZGHtzo

Total BS.

There's some kind of pressure effect in a smaller enclosed space that inflates dB amounts -just look at those car audio "db drags" where they are pulling SPL numbers that seem to defy the laws of physics (180dB +) playing just a tone for a couple seconds.

For example, take an SPL reading of the inside of your sub cabinets at full volume.  You'll get a ridiculously high number that simply doesn't mean anything in the real world outside the box

You then stack all that HT (or Car Audio) equipment in an open stadium venue and it won't come near to what we require as a usable baseline to run a show.

Witness a top fuel dragster up close -or large space rocket launch and note the sensation on your body, then realize that an SPL reading at that point would probably be considerably less than 146.
-If they had a real broadband 146 in that room they probably would have bolted long before reaching that point -even with the plugs in
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Chris Grimshaw

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Re: 146.8db
« Reply #7 on: March 30, 2020, 11:41:27 am »

What the home theater guys get is clean, extension, and dynamic sound out of their systems, which many feel is paramount in a really good surround sound system.

John,

I understand all of that. The speakers I'm using, thanks to some rather convenient room gain (brick house, corner loaded), are flat down to 10Hz and will get to well over 100dB at my listening position.

It's rare that I turn it up that loud, though - most of the time I'll be listening under 80dB.

So, I just don't understand why someone would feel they need to exceed 140dB levels in a domestic space. The last time I experienced something like that, my vision was constantly blurry from the bass, and I had earplugs in and defenders over the top.

I suppose, if your vision is blurry, the projector doesn't need to be anything special.

Chris
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Miguel Dahl

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Re: 146.8db
« Reply #8 on: March 30, 2020, 11:52:08 am »

They are using a SPL lab mini bass meter, it only goes up to 120 hz. I don't know if it's C or A or Z.. If it's C weighted then it's -0.8 dB down @ 63Hz, while A-weighted is -26.2 dB down @ 63Hz relative to Z-weighted. And they had also lots of information at 10Hz, so comparing to A, it's big numbers.
« Last Edit: March 30, 2020, 11:59:41 am by Miguel Dahl »
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Mark Wilkinson

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Re: 146.8db
« Reply #9 on: March 30, 2020, 02:49:20 pm »



Resting on the speculation the the meter is an unweighted, peak reading meter,.... I'd say it's very plausible...even very likely.

You can see they were measuring the bass drop.  A good pro double 18" should be able to ring mid 130's, on Z peaks somewhere in its bandwidth.
Add a 6dB for each doubling of boxes, so 4 good double 18"s, or eight drivers equal +12dB and makes it to 146.8 peak, I think.

My bet is the SPL reading was from somewhere between 45-65 Hz.
I doubt if  any 12dB per octave 'cabin gain' was a factor in the measurement, because given his room dimensions, gain probably didn't start kicking in till below 50Hz. (and then only if his walls and ceiling are pretty stiff)

But then again, who knows what the meter actually meters....

I do know I've had bass drops go flying off the SPL meter like that too, along with half the items in the room not nailed down  .... ;)
Experiencing such awesome bass power can be a lot of fun at home, where it's easier to adhere to a safe listening duration and keep more harmful higher frequency SPL in check.

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Steve-White

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Re: 146.8db
« Reply #10 on: March 30, 2020, 10:54:38 pm »

Total BS...Ö.If they had a real broadband 146 in that room they probably would have bolted long before reaching that point -even with the plugs in
Exactly, they couldn't tolerate 130db for long, let alone 146.
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Caleb Dueck

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Re: 146.8db
« Reply #11 on: March 31, 2020, 01:33:06 am »

Exactly, they couldn't tolerate 130db for long, let alone 146.

It's not full range at that SPL though, just bass. 
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Miguel Dahl

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Re: 146.8db
« Reply #12 on: March 31, 2020, 11:56:13 am »

I once measured a noise musician to about 126dB peak C weighted when I didn't reach the mute button before he pulled out his jack. That was just pulling out a jack.. Haha. So 146 if it's unweighted (Z) seems to me at least somewhat possible when being loud as sh*t is the goal in the low range.

I wonder what a VLFC would measure going full tilt unweighted. It's below our hearing, but it's still energy.
« Last Edit: March 31, 2020, 11:59:02 am by Miguel Dahl »
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Art Welter

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Re: 146.8db
« Reply #13 on: March 31, 2020, 02:51:21 pm »

I wonder what a VLFC would measure going full tilt unweighted. It's below our hearing, but it's still energy.
Not to get into the semantics between hearing and feeling, but most people can detect LF above a threshold of around 90 dB at 16 Hz. Reaching about 125dB at 16 Hz sounds about as loud as 80 dB at 1kHz.
The Meyers VLFC  is rated 125.5 dB (Linear Peak SPL, with crest factor >10.5 dB (M-noise) somewhere in it's passband of 13-30 Hz.
My guess is it has a bit less output than JTR's Captivator 4000-ULF, which can do around 130dB at 30 Hz.

JTR is using 18" 60 pound woofers with as much as 33mm Xmax, almost double the displacement of the better "long throw" drivers used by most companies. Getting 146.8 dB SPL down low with room gain from 9 of those monsters is completely possible, as Ivan said "That's not really all that loud for a "good" home theater".

Art

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Steve-White

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Re: 146.8db
« Reply #14 on: April 03, 2020, 08:36:26 pm »

^^^ I'm going to have to put on the muffs and crank up the JBL MD7 in my den and measure it.  Without hearing protection, regular listening to music when I turn it up,it gets uncomfortable after about 10 minutes of exposure to the point of turning it down or walking out of the room.  I have no idea where my threshold is.

Need to move the second one in there - loaded with JBL 2245 18's.  Just one of them will hammer me pretty good standing 10-12' in front of it.

I doubt it's anywhere near 115db.
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Re: 146.8db
¬ę Reply #14 on: April 03, 2020, 08:36:26 pm ¬Ľ


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