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Discussion Starter · #1 ·
First of all let me clear one thing out! I am not against going with a sub capable of infrasonic frequencies nor will I debate otherwise. However, we recently had a discussion over the Greek AVsite and although I managed to present evidence of plentiful material containing bass info below 20Hz, we also have people that argue that it is meaningless.


So far the best articulated assumptions are:


- Humans can not hear below 20Hz


- Bass below 20Hz muddies the sound and mostly creates noise and disturbance while the punch that one feels from deep bass is in the area above 25Hz.


- Bass below 22-25Hz IS COMPLETELY USELESS (Heavy statement here that I would like your views)


- Good bass is defined by mid bass frequencies and if the mids are not good we get a mess in the end.



Then the suggestion for the best or one of the best subs by a respectable and knowledgeable guy came down to JBL with these particular models:


A) JBL ASH6118



Specifications


Frequency

Range (-10 dB) : 1 cabinet: 25 Hz – 250 Hz,

2 cabinets: 24 Hz – 250 Hz,

4 cabinets: 22 Hz – 250 Hz


Frequency

Response (±3 dB) : 1 cabinet: 30 Hz – 200 Hz,

2 cabinets: 28 Hz – 200 Hz,

4 cabinets: 26 Hz – 200 Hz


Transducer Power

Rating (AES) : 1 cabinet:

1200 W (4800 W peak), 2 hrs,

800 W (3200 W peak), 100 hrs

2 cabinets:

2400 W (9600 W peak), 2 hrs

1600 W (6400 W peak), 100 hrs

4 cabinets:

4800 W (19200 W peak), 2 hrs

3200 W (12800 W peak), 100 hrs


Long-Term System Power Rating (IEC) : 1 cabinet: 800 W (3200 W peak), 100 hrs

2 cabinets: 1600 W (6400 W, peak), 100 hrs

4 cabinets: 3200 W (12800 W peak), 100 hrs


Maximum SPL : 30 Hz – 140 Hz:

1 cabinet: 133 dB-SPL, cont avg

(139 dB peak)

2 cabinets: 138 dB-SPL cont avg

(144 dB peak)

4 cabinets: 144 dB-SPL cont avg

(150 dB peak)


System Sensitivity (dB-SPL, 1W @ 1m) : 30 Hz – 150 Hz:

1 cabinet: 102 dB

2 cabinets: 104 dB

4 cabinets: 107 dB|


Nominal Impedance : 8 ohms per cabinet



B) JBL 4642A




SPECIFICATIONS


Rated Impedance : 4 ohms


Minimum Impedance : 3.2 ohms


Power Handling Capability : -


Continuous Pink Noise : 1200 Watts


Continuous Program : 2400 Watts


Peak Power : 4800 Watts


Output Capability : -


Axial Sensitivity : 50 Hz to 500 Hz; 101 dB, 1W @ 1m

40 Hz to 100 Hz; 100 dB, 1W @ 1m


Net Weight : 98 kg (216 lbs.)


Dimensions H x W x D : 762 mm x 1219 mm x 610 mm

30 in x 48 in x 24 in

Approved by Lucasfilm, Ltd. for THX® installations (Is this of any importance?)
 

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Discussion Starter · #2 ·
No doubt these seem impressive subs at least on paper and specs such transducer power @ 12,800 Watt seem out of this world! (What the hell 12,800??????)


If this is the case and these are the top dogs why none suggests them here for HT use and instead you get 10 different recommendations?



Please comment.
 

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you may or may not be able to hear it but you can feel it. esp pipe organs that go below 20hz. if the sub is good it shouldnt muddle up the sound. i hadnt heard of these before. interesting option.
 

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I predict the word leicester will soon appear in this thread..



Ask that guy if he has those in his theater btw...commercial grade equipment is a tad oversized for anyone with less than unlimited budget for space..


WAF -100 pts BONUS Phase.
 

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SOme thoughts


1: You CAN hear belwo 20Hz-if you get it loud enough.


2: The specs who show are 10dB down on the bottom freq. Therefore it takes TEN TIMES teh power to be just as loud as the upper part of the range. For the horn sub-if you have the upper part of hte response running around 100 watts- then it will take 1000 watts for 25Hz to be jsut as loud. And if you want to turn it up-you will run out of gas on the bottom.


3: The reason for wanting to go lower than 20Hz in HT is for the experience and feeling the lower freq that are present in many movies-explosions-earthquakes-large vehicles and so forth. You need to be able to shake the room and FEEL what the people on acreen are "supposidly" feeling.


4: The 12800 watts is for 4 cabinets AND 6dB higher than continous ratings. No big deal there. Ever been to a large concert? Ever wonder how much power they have on the low end. 12,800 watts would be for small crowds. That's just one or 2 amplifiers.
 

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if you put any of those in an HT room you WILL get deeper extension. those figures are rated for outdoor use or use in a huge concert hall where there is no room gain.
 

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Discussion Starter · #8 ·
Ivan


I got some arguments that you can not reproduce frequencies below 20Hz in a room sized about 26X16 feet and that even if you manage to do it would just cause cancelations and static waves ultimately causing a mess. In other words they state that is not good to have them.


However, isn't Audyssey and other room correction software for subs going to fix this? I have the SMS-1 for example and managed to get a very flat room response in my system while it was not like that before.


Another sub I would like your comments for since they proposed it as BEST no contest for HT use is this (JBL BIAS):

ASB7128


Frequency Range

(-10 dB) : 20 Hz - 1 kHz


Frequency Response

(± 3 dB) : 25 Hz - 1 kHz


Transducer Power Rating : 4000 W (16000 W peak), 2 hrs.


Input Modes : Drivers Parallel / Drivers Discrete


Long-Term System Power Rating : 2400 W (9600 W peak), 100 hrs.


Maximum SPL (1m) : 25 Hz - 200 Hz: 135 dB-SPL

cont avg. (141 dB peak)


System Sensitivity : 25 Hz - 200 Hz: 99 dB-SPL,

1W (2.0V) @ 1m


Nominal Impedance : 4 ohms in parallel-drive mode

2 x 8 ohms in discrete-drive mode


Low Frequency Driver : 2 x 2269H, 460 mm (18 in) dia.,

100 mm (4 in) Dual Coil Dual

Gap neodymium Differential Drive®, VGC drivers


Enclosure : Rectangular cabinet, 16 mm (5/8 in)

exterior grade 11-ply birch plywood


Suspension Attachment : 16 points (4 top, 4 bottom, 4 each side)

M10 threaded hardware



What strikes me here is that they refuse to make a sub that goes lower and people get it as if they know better.


How would this fair to a Danley a PB13-Ultra and a Submersive for HT use? I am asking since people prefer those all the time.


Is there any HARD evidence suggesting that below 20Hz bass IS really important? What does Lucas or Spielberg or Jackson use for example in their HT.



Unfortunately I am the almost a lonely advocate of below 20HZ bass in my country's biggest forums.




Quote:
Originally Posted by mcjasonb /forum/post/16925206


if you put any of those in an HT room you WILL get deeper extension. those figures are rated for outdoor use or use in a huge concert hall where there is no room gain.


But isn't the same true for other subs as well?
 

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Maybe you should tell your Greek friends about the Thigpen Rotary sub. Several people with the money and the room for a proper installation have them and use them.


They have been used in large churches to great effect.


The frequency response is effectively 3 Hz -25 Hz.

http://www.eminent-tech.com/RWbrochure.htm


There are movies with subsonic information that people on AVS want to be able to reproduce. You simply cannot duplicate the experience with subs that cut off at 25 Hz. Helicopter rotors at 105-110 db is quite a thrill. Maybe that is why the sound company used 22 Bag End Subs in mixing the sound track on Black Hawk Down.


The JBls are for the commercial market which is very different, and has been discussed many times before.
 

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Quote:
Originally Posted by theelviscerator /forum/post/16925118


I predict the word leicester will soon appear in this thread..

I had the same thought.




Tim
 

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Discussion Starter · #11 ·
spyboy


I am well aware of the Rotary sub and have indeed presented that over there but as usual they took the piss out of it. Anyway this is the last time I am being bothered about this matter and that is why I started this thread.


Right now the reason I support all this infrasonic bass matter is because of the well respected people of this forum which is the largest meeting point of HT enthusiasts in the world.


If all those bass experts work on such low bass and so many people go for it and get excellent results then that is enough.
 

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Quote:
Originally Posted by Ivan Beaver /forum/post/16925153


SOme thoughts


1: You CAN hear belwo 20Hz-if you get it loud enough.


2: The specs who show are 10dB down on the bottom freq. Therefore it takes TEN TIMES teh power to be just as loud as the upper part of the range. For the horn sub-if you have the upper part of hte response running around 100 watts- then it will take 1000 watts for 25Hz to be jsut as loud. And if you want to turn it up-you will run out of gas on the bottom.


3: The reason for wanting to go lower than 20Hz in HT is for the experience and feeling the lower freq that are present in many movies-explosions-earthquakes-large vehicles and so forth. You need to be able to shake the room and FEEL what the people on acreen are "supposidly" feeling.


4: The 12800 watts is for 4 cabinets AND 6dB higher than continous ratings. No big deal there. Ever been to a large concert? Ever wonder how much power they have on the low end. 12,800 watts would be for small crowds. That's just one or 2 amplifiers.

Agreed with all your points, but there are some movies that have such low bass that most even expensive subs cant play extremely loud.


There can never be enough bass.


Quote:
Originally Posted by mcjasonb /forum/post/16925206


if you put any of those in an HT room you WILL get deeper extension. those figures are rated for outdoor use or use in a huge concert hall where there is no room gain.

Well of course that would happen, putting a bass transducer in an enclosed space will allow the soundwaves to bounce off that enclosure, thus amplifieing the waves.
 

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Discussion Starter · #13 ·
Guys how does the last JBL I linked (ASB 7128) fare against the known offerings performance wise? It is also not very expensive either at 3,000 Euros...



Yet, is it true that to reproduce below 20Hz you need a "MINIMUM" length in your room so the sound waves have enough space to develop?
 

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Quote:
Originally Posted by theelviscerator /forum/post/16925118


I predict the word leicester will soon appear in this thread..



.


No worries, I think JBL4565 has been banned and now lives over at AH as a guy named "Bob" aka Lordoftherings.
 

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Anyone who says humans can not hear below 20 hz is ignorant. I think that comes from miss reading hearing tests with 75 db or lower test tones. If the spl level is low, no, but at 100-115 db most people can hear tones into the teens or below. I can eAsily hear a 15 hz sine wave, 8 hz is not necessarily heard, but I can definitely perceive it.


If the sub or subs are cabable, they can produce deep base without sacrificing the more impactful upper bass region. See Seaton Sound products, and a growing number of competitors at various levels.


Finally, you can easilly settle this debate yourself with a few minutes of listening. Find a system that is flat to low teens or below and try some deep material with and without a subsonic filter at 25 hz. Unless you listen at low volume levels, the benefits will be obvious, and you will shake your head in disbelief at the idiots who are making these claims. Also, fwiw, the content below 20 hz is often real and often there in sounds we experience everyday, it is not just crap added to a soundtrack or extraneous noise that slipped through.
 

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Quote:
Originally Posted by croseiv /forum/post/16926626


No worries, I think JBL4565 has been banned and now lives over at AH as a guy named "Bob" aka Lordoftherings.

Whoa, can't even find any of his AVS posts using advanced search. What would have caused his being banned?
 

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Quote:
Originally Posted by JargonGR /forum/post/16926622



Yet, is it true that to reproduce below 20Hz you need a "MINIMUM" length in your room so the sound waves have enough space to develop?

no, quite the opposite. The smaller the room the more room gain which makes it easier to produce the sound. Sound is a preasure variation and the preasure in a small room or car can be varied at low frequencies. In fact if the space needed to be the length of a wave, a car could not have base below 100-150 hz.


FWIW my room is 24x17.5x8 and I get good bass down to around 7 hz. You can measure in multiple locations and see there is no mess of wave cancelations in the sub 25 hz region, although there are above just like any real room.
 

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Tell your group they are full of themselves. I hear less than 20 hz all the time, you just need enough output to do so. It does not muddy the midbass at all. It adds to the experience. There are many movies with less than 20 hz info and they are missing out, they are just mad that others are enjoying the full spectrum.
 

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Quote:
Originally Posted by snpanago /forum/post/16926797


Whoa, can't even find any of his AVS posts using advanced search. What would have caused his being banned?

This is a good question, and I'm not certain. My guess is just that, a guess. He hasn't posted since June 12th for what ever reason, and based on how he used to post, it's very surprisng that he just "stopped" unless he was made to.
 
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