This is fastinating and maybe why I find the ‘roar’ or paraflex with an absorber stub so brutale (punch/thump) ?
Mark,
In the scientific audio world, there is the time domain, and the frequency range.
They are not “equal”, though using a Laplace or Fourier transform they can be converted to each other.
“Transient response” is the response to an impulse or step signal.
To measure transient response, an abrupt change to the input signal is made and the response of the output is compared over time.
Frequency Response is typically shown using a “Bode plot”, a graph that shows how a system’s response changes in magnitude in decibels and phase in degrees to a linear time-invariant signal.
Anyway, to form a mental picture of the difference between the two, imagine a linear time-invariant signal, a sine wave signal sent through a spring reverb, a device using a transducer at one end of a spring, and a pickup at the other end.
Now imagine the output signal is equalized for flat frequency response from 20 to 20,000 Hz, a “perfect” frequency response.
Now imagine a waveform with wideband abrupt transient changes (say a Billy Cobham tight kick drum sample..), going through the spring- the output will be smeared in time (and phase..) over several seconds, the classic “boingy” sound replacing the thwack. You no longer will feel the baseball bat to the chest impact.
To a lesser extent, we are stuck with the “spring reverb” problem in every speaker, the mass required to keep a diaphragm stiff while carrying the weight of a heavy voice coil required to handle the power to shift the weight of large quantities of air 20-100 times a second results in some transient lag and overshoot, regardless of it’s frequency response.
Usually, the higher frequency broad spectrum transient content precedes the low frequency content, but that is signal dependent..
The only practical solution to the transient response problem is to “divide and conquer”, reducing the bandwidth of the subwoofer doing the “heavy lifting”, or using far more lightweight woofers to achieve a wider bandwidth, which brings in it’s own time domain issues as the source becomes large compared to the wavelength it must reproduce.
Art
Hi Art, two things...
First, all our measurements originate from the time domain. An impulse response is taken, and as you say converted, to the give us the frequency domain.
You can't directly take a frequency domain measurement.
Point is: measurements originate from the time domain, and not from the frequency domain.
Second, yes, transient response equals impulses response....(at least in the scientific audio world i work in 🙂
Since impulse response is the originating measurement, and frequency response (mag and phase) are its transforms. Inverse transforms, to go back from the frequency domain to the time domain, are after the measurement fact reversals....not measurement originators.
So it only follows that time domain to frequency domain are indeed identical tie togethers...in all cases.
Excellent impulse response = excellent transient response = excellent frequency magnitude and phase response.
Truncated or mis-time aligned impulse = diminished transient response = limited bandwidth and/or irregular frequency response.
Transient response, being impulse response, does equal frequency response...in the sense they completely describe each other.
I don't really follow your spring example. My measurements of everything from single element full-range electrostats to 5-way MEHs, when tuned to flat mag and phase, ie near perfect impulse response, do not show the time smear you speak of.
So I don't think it's a matter of divide and conquer, to get good transient response.
I see it as a matter of just getting all drivers sections to working together properly...iow, good ole flat mag and phase tuning (which gives most excellent transient response 🙂
As with most bass heads they like those big magnets.
Fast transient with music playback and fast transient with musician is little different.
Your aware of the actual attack in real time.
Anyway blah blah. If it was loud enough typical kick drum or good bass player could chest thump.
Would say even the low Qts peavey super structures laid out some quick thumps. Direct Radiating or horn loaded.
The Typical SP1 type horns or even some typical Vega B36 could do it. Depends on the music.
My uncle was well aware of the D-130 craze started from 65 to 69 really known from 69.
He had the classic 4530 done diy heard D or K series in those. First time I remembered chest thump as a kid.
With bass boost even my sealed Ampeg would do it, and those are pretty bloomy high Qts speakers
Complete oppsite of most the JBLs. But sealed they knocked a thump. My whole playing style changed.
Chest thump? 8 or so speakers will do it lol. Fast attack. With electronic drums, right envelope you an hammer people hard
Fast transient with music playback and fast transient with musician is little different.
Your aware of the actual attack in real time.
Anyway blah blah. If it was loud enough typical kick drum or good bass player could chest thump.
Would say even the low Qts peavey super structures laid out some quick thumps. Direct Radiating or horn loaded.
The Typical SP1 type horns or even some typical Vega B36 could do it. Depends on the music.
My uncle was well aware of the D-130 craze started from 65 to 69 really known from 69.
He had the classic 4530 done diy heard D or K series in those. First time I remembered chest thump as a kid.
With bass boost even my sealed Ampeg would do it, and those are pretty bloomy high Qts speakers
Complete oppsite of most the JBLs. But sealed they knocked a thump. My whole playing style changed.
Chest thump? 8 or so speakers will do it lol. Fast attack. With electronic drums, right envelope you an hammer people hard
What if we band limit the test, as is the convention with texts discussing the transient response of a filter. They tend to apply a single frequency at the filter frequency to show the time domain effect of damping.
Are you an advocate of the Royal Raymond Rife machine use as a medical modality?
First, there was time, or was it distance, or was it magnitude. Oops, forgot to measure 😉
Second, in the scientific world, equal implies being identical in value, magnitude, or some specified quality.
Transient response is the response to an impulse, no more "equal" than a hammer, a nail and piece of wood are.
Again, you are conflating disparate unequal concepts.
Impulse signal time does not equal decibels or angles of degree.
A loudspeaker can have flat frequency magnitude response while having thousands of degrees of phase difference over the flat frequency range.
The reverb spring example was an analog demonstrating that time, phase and frequency response are related to each other, but not "equal" to each other.
The FIR filters required to correct time domain issues (retarded transient response, phase rotations, ringing) take far more signal input to output time to accomplish than simply correcting magnitude response.
"All drivers sections working together properly" might be considered= to "divide and conquer" 🙂
Art
Thanks for the interesting discussion so far.
I suppose realisation of "chest kick" effect, besides being system dependent, is also source dependent. Specifically, source material/media: there will be recordings that contain "kick" material to greater or lesser extent. As an aside to the topic - but still related - what tracks are representative of music with good kick content? Recommendations?
I don't mean to derail the discussion, but I do think that having common reference tracks for the purpose of experimentation would be useful.
I suppose realisation of "chest kick" effect, besides being system dependent, is also source dependent. Specifically, source material/media: there will be recordings that contain "kick" material to greater or lesser extent. As an aside to the topic - but still related - what tracks are representative of music with good kick content? Recommendations?
I don't mean to derail the discussion, but I do think that having common reference tracks for the purpose of experimentation would be useful.
Do you mean using a single-frequency tone burst as the stimulus signal?
I'm thinking so...
Even single-frequency tone bursts have a bandwidth that exceeds their single frequency. The bandwidth is primarily a function of the windowing used to define the envelope of the burst, but also the number of cycles in the burst.
Here's snip from a recent SynAudCon article showing this ...https://www.prosoundtraining.com/2025/01/11/loudspeaker-maximums-part-2-peak-spl/
It's easy to audibly explore the different bandwidths of a same single-frequency burst, using REW's tone burst generator.
(Well, I should say it's easy if you have an active speaker and can play only one driver section at a time.)
Choose a burst frequency solidly inside the woofer's range. Select a Hann window or any other mild start and stop window. Play the burst with only the woofer active, and then with only the mid-range active. The strong burst will likely be audible only from the woofer.
Switch the window to Rectangular. Play through both again.
It's likely a fainter higher frequency burst will be heard from the mid-range, along with the strong burst from the woofer.
I think this burst test is an excellent demonstration of why time domain response (transient response) is the originator of frequency response.
Even a single frequency has a bandwidth spectrum when not a continuous signal.
And the simple single freq burst illustrates why a kick in the chest, is not just about finding the predominant frequency that gives the kick.
Sure, there is a frequency range that holds strongest kick signal. It's not really a fundamental frequency in the harmonic sense, but more a foundational frequency in the complex music waveform sense.
The complex kick waveform has an abundance of signal content beyond the kick's foundational frequency.... that define the feel of the kick. (not to mention the total sound of the kick)
All of the contributing frequencies need to be reproduced together, in time and in phase.
Back to transient response equals impulse response equals frequency response (defined as mag and phase) 🙂
How would this work? The frequencies involved and their affect, good or bad, on a particular microscopic‘pathogen’ or cell type?
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I was kidding. Your question is very similar to what I asked some friends who believed in this stuff.
sorry to derail the tread.
sorry to derail the tread.
Isn't it more the other way around - most of the time domain properties display is derived from/by the frequency domain - most REV (etc) users see an impulse trace that have been FFTed from a slow FR sweep...
//
The concept of transient response is not tied to speakers and has been around for a long time serving physics in the wider range. It's often used in electronics and you'll see it describing things as simple as settling time and the term is often used to describe level vs time for a filter taken at one frequency.
It could be a single sine, or anything really. Frequency response doesn't have to be a factor of interest.
Let an actual drummer answer the question... You can't even hear the kick in @Speedysteve7 song....
Also.... Do not underestimate the comments about Voicing... A nice smooth FR from about 300hz and down will give you all the kick you want as long as it is compression free.
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Not deep enough for me.
This is better on my system
Old but gold.
I post Spotify here because most here might have access to it.
I listen using qobuz.