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Author Topic: What Is the Real Lowest Audible Frequency & Best Subs to Achieve It?  (Read 20129 times)

Jared Bartimus

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Re: What Is the Real Lowest Audible Frequency & Best Subs to Achieve It?
« Reply #10 on: January 26, 2011, 01:51:12 pm »

The JTR Orbit Shifter HT seems to have good reviews from what I have seen.

http://jtrspeakers.com/home-audio/orbit-shifter-lf/

In a corner I think that should have 109dB sensitivity.  I wonder if Jeff has a chart showing the actual max output at 25hz because 139dB corner loaded seems a 'bit' unrealistic.
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Alan Singfield

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Re: What Is the Real Lowest Audible Frequency & Best Subs to Achieve It?
« Reply #11 on: January 26, 2011, 02:17:11 pm »

http://www.rotarywoofer.com/


Just a suggestion.




Edit: incorrect URL
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Alan Singfield

Sound Engineer
Analogue Live Productions Ltd
Glasgow, Scotland

www.analoguelive.co.uk
www.myspace.com/alanthesoundengineer

Art Welter

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Re: What Is the Real Lowest Audible Frequency & Best Subs to Achieve It?
« Reply #12 on: January 26, 2011, 04:21:07 pm »

Alan Singfield wrote on Wed, 26 January 2011 12:17

http://www.rotarywoofer.com/

Just a suggestion.

Edit: incorrect URL


index.php/fa/34866/0/

They want a lot of money for a maximum acoustic output of only  115dB between 1 and 20Hz.

Probably really cool for sound effects, but there is not much music that goes below 16 Hz.

For a fraction of that cost, there are many subs with more output down to below 10 Hz.
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Tim Padrick

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Don Gspann wrote on Wed, 26 January 2011 07:49

.... I'm sure the transient response is much better on the new subs,.....


Given the slow rise time of the frequencies that are fed to subwoofers, I think that the term "transient response" is not applicable.

Art Welter

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Tim Padrick wrote on Wed, 26 January 2011 23:10

Don Gspann wrote on Wed, 26 January 2011 07:49

.... I'm sure the transient response is much better on the new subs,.....


Given the slow rise time of the frequencies that are fed to subwoofers, I think that the term "transient response" is not applicable.


Transient response describes the behavior of a system following a sudden change in its input.
It is not limited to high frequencies.

Many sub designs suffer from the persistence of cone movement or stored energy in the system after the signal has stopped,  underdamped transient response.

Listening with two systems equalized for identical response, a sub with poor transient response, as described above, will subjectively sound “tubby” or “slow”. Percussive notes tend to blend together, bass lines become less recognizable.

I hate it when that happens  Laughing .
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Tim Padrick

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Art Welter wrote on Thu, 27 January 2011 11:07

Tim Padrick wrote on Wed, 26 January 2011 23:10

Don Gspann wrote on Wed, 26 January 2011 07:49

.... I'm sure the transient response is much better on the new subs,.....


Given the slow rise time of the frequencies that are fed to subwoofers, I think that the term "transient response" is not applicable.


Transient response describes the behavior of a system following a sudden change in its input.
It is not limited to high frequencies.

Many sub designs suffer from the persistence of cone movement or stored energy in the system after the signal has stopped,  underdamped transient response.

Listening with two systems equalized for identical response, a sub with poor transient response, as described above, will subjectively sound “tubby” or “slow”. Percussive notes tend to blend together, bass lines become less recognizable.

I hate it when that happens  Laughing .


My thinking is that the term transient response describes the DUT's performance on the leading edge only - that anything that happens after the peak is reached has to be described by another term.  No?

Art Welter

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Tim Padrick wrote on Sat, 29 January 2011 01:38

Art Welter wrote on Thu, 27 January 2011 11:07

Tim Padrick wrote on Wed, 26 January 2011 23:10

Don Gspann wrote on Wed, 26 January 2011 07:49

.... I'm sure the transient response is much better on the new subs,.....


Given the slow rise time of the frequencies that are fed to subwoofers, I think that the term "transient response" is not applicable.


Transient response describes the behavior of a system following a sudden change in its input.
It is not limited to high frequencies.

Many sub designs suffer from the persistence of cone movement or stored energy in the system after the signal has stopped,  underdamped transient response.

Listening with two systems equalized for identical response, a sub with poor transient response, as described above, will subjectively sound “tubby” or “slow”. Percussive notes tend to blend together, bass lines become less recognizable.

I hate it when that happens  Laughing .


My thinking is that the term transient response describes the DUT's performance on the leading edge only - that anything that happens after the peak is reached has to be described by another term.  No?

No.

I have not found a single definition of transient response that does not take the tail end of a signal into account as well as the front end.

Webster’s definition of Transient: “passing especially quickly into and out of existence.”

McGraw-Hill Science & Technology Dictionary defines Transient Response as: “The behavior of a system following a sudden change in its input.”

Wikipedia: “In Electrical Engineering and Mechanical Engineering, a transient response or natural response is the response of a system to a change from equilibrium. Specifically, transient response in Mechanical Engineering is the portion of the response that approaches zero after a sufficiently long time (i.e., as t approaches infinity). “

But even looking at the transient response at the  start of  a signal, there are differences that can be observed between woofers.
A 10” woofer with a powerful magnet can accelerate a light cone faster at the onset of a signal than an 18” heavy cone woofer with a weak  magnet. The former would  have better transient response than the latter.
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Mac Kerr

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Art Welter wrote on Sat, 29 January 2011 14:01

McGraw-Hill Science & Technology Dictionary defines Transient Response as: “The behavior of a system following a sudden change in its input.”

Wikipedia: “In Electrical Engineering and Mechanical Engineering, a transient response or natural response is the response of a system to a change from equilibrium. Specifically, transient response in Mechanical Engineering is the portion of the response that approaches zero after a sufficiently long time (i.e., as t approaches infinity). “

But even looking at the transient response at the  start of  a signal, there are differences that can be observed between woofers.
A 10” woofer with a powerful magnet can accelerate a light cone faster at the onset of a signal than an 18” heavy cone woofer with a weak  magnet. The former would  have better transient response than the latter.



Of course, there are no sudden changes in input in a sub. All changes are gradual because of the LPF eliminating those pesky rapid changes. Obviously there can be mechanical systems that are so slow in response that even a relatively slow change to the input of the system can't be accurately tracked by the output. Since it is a case of the output not tracking the input I suppose that could be thought of as transient response. It isn't transient response in the sense that that term has in any other part of the system.

Mac
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Art Welter

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Mac Kerr wrote on Sat, 29 January 2011 12:25

Art Welter wrote on Sat, 29 January 2011 14:01

McGraw-Hill Science & Technology Dictionary defines Transient Response as: “The behavior of a system following a sudden change in its input.”

Wikipedia: “In Electrical Engineering and Mechanical Engineering, a transient response or natural response is the response of a system to a change from equilibrium. Specifically, transient response in Mechanical Engineering is the portion of the response that approaches zero after a sufficiently long time (i.e., as t approaches infinity). “

But even looking at the transient response at the  start of  a signal, there are differences that can be observed between woofers.
A 10” woofer with a powerful magnet can accelerate a light cone faster at the onset of a signal than an 18” heavy cone woofer with a weak  magnet. The former would  have better transient response than the latter.



Of course, there are no sudden changes in input in a sub. All changes are gradual because of the LPF eliminating those pesky rapid changes. Obviously there can be mechanical systems that are so slow in response that even a relatively slow change to the input of the system can't be accurately tracked by the output. Since it is a case of the output not tracking the input I suppose that could be thought of as transient response. It isn't transient response in the sense that that term has in any other part of the system.

Mac


An underdamped woofer can persist in movement for several cycles after the signal is stopped, an example of a electro mechanical system that is so slow in response that a change to the input of the system is not accurately tracked by the output.

I guess we have a different idea of what "sudden changes" are.

100 "changes" a second is not sudden?
Of course, that 100 changes would be only the upper fundamental frequency, when a woofer is responding to a musical signal, there are multiple frequencies involved, the "changes" it needs to respond to are in the thousands.

When are changes sudden, at 1000, 10,000 Hz ?

How does transient response apply to one set of frequencies and not to another?



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Mac Kerr

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Suddenly it's slower
« Reply #19 on: January 29, 2011, 04:17:34 pm »

Art Welter wrote on Sat, 29 January 2011 15:18

100 "changes" a second is not sudden?
Of course, that 100 changes would be only the upper fundamental frequency, when a woofer is responding to a musical signal, there are multiple frequencies involved, the "changes" it needs to respond to are in the thousands.

When are changes sudden, at 1000, 10,000 Hz ?

How does transient response apply to one set of frequencies and not to another?


Yes, the changes it needs to respond to are in the thousands, but all of them are below about 100Hz. In a sub, maybe an impulse with a 2.5ms 1/4 wave rise time or greater can be called "transient". What often gets mentioned in discussions about sub "transient response" in subs is the first snap of the beater on the bass drum. It you compare the rise time of that first impulse as heard by the mic to the signal as heard by the sub, the signal at the sub won't look so much like a "transient". If the "snap" of a bass drum is around 4kHz it has a rise time 1/40th of that of 100Hz, or 0.0625ms.

If "transient response" is the ability of the output to track the input, there is no lower limit to what a transient is, it is defined by the mechanical system's ability to track the input. If a "transient event" is defined by the frequency content of the original full range source, what happens at the sub is slow motion.

Mac
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