How Deep Must the Bass Be?

[Robbo99999]

Late to reply because this is a tough question.

1) I lean toward lean bass as a preference. (Likely because so many subwoofers seem slow on the uptake.) So, first, is speed of the woofer/subwoofer, no matter how low I wanna go. (I think SVS does a good job, and I have some Genesis servo woofers that can keep pace in a good way. I also use some old Acoustat 2+2 speakers as woofer only and they are speeee-dy!)

2) More than thumping the house, I think a good woofer adds atmosphere and 'air,' which might sound nuts, but it really seems to enhance spatial cues and sense or 'place.' Woofers that make it into the 35-40 Hz range start to achieve this, so that would be my minimum in terms of the question.

3) The main speakers has to be able to handle dynamic transients at higher frequencies to really make things work. Bass transients come with a lot more than just bass frequencies, so the main speakers need to be stout enough to work with the woofer, as well.

4) I think there is ample bass content into the 20 Hz range that makes reproducing those sounds very worthwhile. It can add 'emotion' to how the music impacts me and enhances the soundstage. (Subjectively speaking, I don't know how an objectivist would feel about my listening impression. So, take this is as worthless subjective listening feelings.)

All that adds up to a vote for a deep reaching woofer. If you are going to to do it, do it well! Plus, great fun playing with placement and settings....adjustability is another important part. To sum up, how deep? "Balls deep, but fast."

Slow & fast hooey! I think the only statement I agree mostly with in your post is "I think there is ample bass content into the 20Hz range that makes reproducing those sounds very worthwhile."

 

[rdenney]

Google "transient response."

Maybe my wording was inelegant. Shouldn't be controversial. (I think you can even measure it.)

But that's the point. Transient response is just a fragment of high frequencies. You actually don't want a sub to even see transients that require slew rates higher than you'd see at the crossover point. The crossover (hopefully) simply won't pass waveforms that steep and the steepest part of the transient will be heard in your other speakers. A sub responding to a transient that is steeper than needed for the crossover frequency would be the source of localizable noise and would call attention to itself unpleasantly.

By the way, there is no such thing as a pure transient response except by adding DC to the signal path. The glitch when the DC is added usually makes undesirable noise. It certainly does not happen in music, or even in sound effects for movies. If the voltage returns after the transient, then it becomes the sum of a stack of sine waves that are superposed on one another. Again, you want the crossover to filter out any of those that exceeds the crossover frequency.

Some measurements of maximum slew rate, for example, try to determine how steeply the signal can climb the leading edge of the ideal square wave. The last thing I'd ever want to hear from a sub is a square wave, because that waveform is the sum of a fundamental and a whole range of overtones. Once I filter out the overtones, I might have the fundamental and maybe the second and third harmonics. Anything above that creates undesirable noise rather than mere harmonic distortion. So, the crossover should filter that square wave into just a couple of frequencies, none of which require a steep slew rate.

Rick "'fast' is a surrogate for 'clean', meaning free of distortion" Denney

 

[Blumlein 88]

The thread title is literally "how deep must bass be".

If that's not informed by how deep the bass content "can be" then there is no answerable question.

Vast majority of bass is higher than 40hz
Some exists between 20 and 40
A small percentage of movies and music have bass down to 6hz (give or take) .

All of that bass can be heard (edit: meaning not all bass in those ranges can be heard on every track; but there is bass in all of those regions that can be heard on some tracks), but may not have tonality. Now the OP has to make a subjective decision.

Also, the fact that the OP was specifically pondering the audibility of 16hz tones for his personal enjoyment is a big clue that their question isn't limited to the most common bass frequencies, but the possible bass frequencies.

That said, haven't seen the OP for a while... We may be talking to ourselves.

Edit: We could interpret the question to be asking 'what's the least bass extension needed to still enjoy music', and then I would argue a much higher number; I can enjoy great music over phone speakers. But again, that interpretation doesn't seem defensible in light of the OP's additional questions.

Well the OP specifically said heard, and not felt. Leaves out infrasonics in movies etc. So in the range heard, you look at how high the threshold and you look at recordings. I'm not arguing there are not some that get really low. They are rare. One thing for certain is you cannot hear what is not on the recording. Few recordings have really low content other than leaked noise/rumble whatever. The OP didn't mention recordings or music so maybe he just wanted the pure physical limits of hearing.

The 3-7 hz range is where you can make people nauseous so I don't see the sense in one thinking that is needed. Infrasonics are typically defined as below 20 hz so that is one answer to the OP. It seems ears hear from 10-20 hz, but some reporting by research is that it is no longer perceived as tones below 20 hz. More like discontinuous pulses. At the lower end around 10 hz it is reported to be felt as fluctuating ear drum pressure. And those frequencies require very high levels to be heard at all. One example is many modern cars if you open a rear window. You'll get a low frequency pulsing that is often uncomfortable. Using microphones with some useful response down there I've measured a handful of vehicles and those pulsing throbbing instances are between 10-20 hz. They don't sound like a low frequency tone. Yet they are a continuous resonance.

Plenty of comments here are also making the mistake about what instruments produce vs what is recorded. Even many fine recordings don't capture much of the really low content. Probably much more often when there is such content people are hearing the harmonics. The threshold at those low ranges changes steeply with frequency.

 

[Sal1950]

My goodness, over 22 pages, 420 posts, and the beat goes on.
The bottom line answer is 20hz X xSPL @ x%THD = $$$
In this equation, "the money talks and the BS walks"

 

[Blumlein 88]

I disagree that your conclusion pertains to me, and one could do that experiment, or one could just listen to music in a car or in a supermarket and get the inverse effect - roll off. However, your experiment seems to me to be an attempt to try not to hear music, for bass has a context - the rest of the spectrum. The OP, it seems to me wants, to engage in argument about what is ultimately subjective, but like I sald 'There cannot be debate about taste' What is musical? What can be heard? How to increase musical enjoyment? - All fine questions for a physicist working on research or a philospher maybe, but there will never be agreement here, because we all know what we like; however, it seems you agree with my only point, that there is information below 40. On my system, with my music, in my room - it is a lot of informaiton, but I could only show you.

Well how much information can it be? Tones at very low frequencies with very high thresholds so the dynamic range available is going to be highly limited. Even when a recording has it the times it will be above threshold are going to be limited. It isn't nothing, but as I've said we are deep into diminishing returns and for relatively uncommon recordings. A piano low note is 27.5 hz. A tuba 30 hz. Double bass 32 hz. Other than an organ is there any instrument that plays lower? Big woofers that can go lower do better at the more common frequencies a little higher. I think that is actually what people are hearing.

 

[Sokel]

I think I own the spectrogram and analysis of the one I posted and @rdenney broke down in detail:




Not bad for a 70 yo destined to be played through reel to reel an vinyl,huh?

(I just wonder what speakers went down there back then,I suspect some but I don't know)

 

[Blumlein 88]

I think I own the spectrogram and analysis of the one I posted and @rdenney broke down in detail:


View attachment 324981 View attachment 324982

Not bad for a 70 yo destined to be played through reel to reel an vinyl,huh?

(I just wonder what speakers went down there back then,I suspect some but I don't know)

Looks an awful lot like some sort of resonance. Room resonance maybe. Down near 30 hz. Or am I missing this being an organ recording?

 

[Sokel]

Looks an awful lot like some sort of resonance. Room resonance maybe. Down near 30 hz. Or am I missing this being an organ recording?

It's the wav analysis of the play I posted a while back at this thread.

 

[rdenney]

[snipped stuff I agree with]

Plenty of comments here are also making the mistake about what instruments produce vs what is recorded. Even many fine recordings don't capture much of the really low content. Probably much more often when there is such content people are hearing the harmonics. The threshold at those low ranges changes steeply with frequency.

I did qualify my comments to assume that what the instrument produced was actually recorded. That certainly does not always happen, but I don't think it's unreasonable to want a system that avoids assuming that content is never there. When I record myself, I try very hard to capture linearly down to at least 30 Hz, which is below what I can play with authority. With even my inexpensive condenser mics, I don't usually have to work at that too hard.

Rick "agreeing that lots of what people hear are the harmonics" Denney

 

[Anton D]

Well, as long as I have committed this faux paus, why stop now?

Happy to be schooled, not meant any other way...

Also, apologies if this other forum is a bad word here, I don't know if it's a 'good' forum, or a 'bad ' forum...

The topic was discussed there, and there are people on both sides.

https://www.avsforum.com/threads/subwoofer-transent-response.529189/

Different quotes:

1) "The short answer is that if a speaker is playing a frequency, it is - by definition - "fast enough". This seems to be the ASR consencis answer, but then there is this...

2) "Actually, every subwoofer I've tested thus far has shown a better looking impulse response that the one you hotlinked, with ringing typically stopping after about 40 ms, whereas the Earthquake 15 continues to ring even past 75 ms."

So, this would not be audible?

__


The next thing is from a manufacturer, SVS, so they have skin in the game, but if they include this concept in their design, are they being dishonest?

"...fast speed in musical and cinematic transients so they can keep pace with the content with complex basslines, aggressive action scenes and other full range content with no overhang, smearing or loss of detail."

If not transient response, what measurement would set an apparently 'slow' sub from one that is sonically more appealing in this regard?

 

[dualazmak]

One experiment I keep running, is the ability to easily vary the subs' high-pass frequency in real time, to be able to hear/judge how low a track has content.

Yes, I often do the same using DSP software EKIO's output gain-change/mute and High-Pass (Low-Cut) Fq real-time controls for L&R sub-woofers.

And these flexible on-the-fly controls on subwoofers are also nice to suppress/eliminate unacceptable low-Fq air conditioning noises given at the recording venue (and poor recording/mixing QC checking it), if needed (ref. here).

 

[Anton D]

I see what some people so kindly mention in their posts, but is this next opinion true?

From another forum:

"
Any driver that employs a voice coil: speed is dependent upon the inductance of the coil and all wiring to it from the amplifier. There was a whitepaper done on this a couple years ago. Inductance alone, was found to be the determinant factor in driver transient response.

The rate of change of acceleration IS the transient response - it's what dictates how fast the driver can change speed, which also means it dictates how fast the driver can move from position to position.

BLi = ma


So, the Motor Force Factor BL times the current i equals the moving mass of the driver m times the
acceleration of the driver a.

BL is time invariant, assuming small excursions
i is the current into the driver
m is mass.
a is the acceleration.

So, let's rewrite the equation, and replace the time-invariant parameters with a simple "C" to indicate a
constant (a parameter that does not change with time):


Ci = Ca (eq 3) or i :: a (eq 4)


This says that the change in acceleration of a driver - how fast it can change position - is
strictly a function of the current through the driver.

A loudspeaker is a coil of wire wound on a former that attaches to the
cone. The current flows through the coil, creating an alternating magnetic field that interacts with the static
magnetic field of the permanent magnet. So, what could limit current flow? Well, what does a voice coil
look like? How about an inductor?

So, what about an inductor will alter the way current flows? Well, inductors don't like to have the current
flowing through them change. They like to hold the current constant. They will allow you to change the
current flowing in them, but the bigger the inductor (or, the higher the measured inductance) the longer it
will hold the current before it starts to change.

It turns out that transient response of a woofer is not a function of the moving mass, as is commonly espoused (one of the most infamous audio myths). In actuality, it is based upon the inductance of the driver. And the greater the inductance, the slower the driver - the lower the transient response."

Is that all correct?

Then, someone added this...

"Consider next reactance, as another example of opposite behavior. Conventional subwoofers have large reactance, plus severe reactance changes, at low frequencies. This reactance comes from the driver's free air resonance, compounded by the resonance of the enclosure volume with this driver, compounded by the resonance of the port or vent (if any). This reactance creates four huge sonic problems, which preclude correct bass reproduction. First, this reactance sets up a barrier fence at a certain frequency, below which the conventional subwoofer cannot go, to reproduce the full bass spectrum. Second, this reactance stores energy and then releases it much later in time (as bass overhang and ringing). This spurious delayed energy release not only creates a phony bass sound (boomy overhang), but also obscures subsequent musical information (of all frequencies) that happens to occur immediately after each bass transient. Third, this reactance robs energy from the initial bass transient (the energy contained in that delayed energy release has to be stolen from somewhere), so the initial attack of bass transients lacks sufficient dynamic impact. Fourth, this reactance grossly corrupts the time domain waveform put out by the conventional subwoofer, so that its contribution to the overall musical transient does not properly add up with and cohere with the waveform put out by the main loudspeaker for this same musical transient."

Is there a better term for describing the impression of 'fast" or slow" sounding woofers?

 

[GXAlan]

I often hear of ‘slow’ subs I guess they play 20Hz at 19 very poor.
Keith

It’s comes across as condescending when you make a comment that way. No one actually is making the claim that the “speed” is different since the speed of sound is fixed as is the frequency. Its like criticizing someone for calling food “hot” when the temperature is cold, but the person is using “hot” to describe “spicy.”

There is definitely a difference between fast and slow subwoofers, and it may be as simple as distortion or cabinet resonance.

Here’s a question. If I play back a 30 Hz tone for 3 seconds at 100 dB, I would expect my woofer to vibrate 90 times at some level of excursion to achieve that SPL. Imagine after the 90th oscillation I unplug the sub.

Are there scenarios where one woofer at the end of the test single oscillates one more time at a lower level of excursion and scenarios where another product oscillates twice and another that doesn’t oscillate at all?

 

[Axo1989]

It’s comes across as condescending when you make a comment that way. No one actually is making the claim that the “speed” is different since the speed of sound is fixed as is the frequency. Its like criticizing someone for calling food “hot” when the temperature is cold, but the person is using “hot” to describe “spicy.”

There is definitely a difference between fast and slow subwoofers, and it may be as simple as distortion or cabinet resonance.

Here’s a question. If I play back a 30 Hz tone for 3 seconds at 100 dB, I would expect my woofer to vibrate 90 times at some level of excursion to achieve that SPL. Imagine after the 90th oscillation I unplug the sub.

Are there scenarios where one woofer at the end of the test single oscillates one more time at a lower level of excursion and scenarios where another product oscillates twice and another that doesn’t oscillate at all?

I'm all for spicy subs.

 

[Axo1989]

Is there a better term for describing the impression of 'fast" or slow" sounding woofers?

It's the usual semantic issue that numerate but not contextually literate types react to here at times. We have fast/slow, tight/loose, clean/dirty to describe various subjective impressions wrt bass. I'm sure there are more I haven't thought of. Smooth/boomy. There are characteristics of subwoofer drivers, cabinets, setup and room interactions that lead to these sonic impressions. As usual there are devils in the details. Since I don't have and haven't set up subs I'll mostly be reading what others have found beyond my basic understanding (and I'm somewhat innumerate, so you'll lose me fast with algebra, but don't let that stop anyone).

 

[Sokel]

We're not talking about group delay i hope.

Other than that,expressed speed is usually associated with tightness in the subjective literature.
Is something about control that they probably want to express,we all suspect what they mean one way or another.

(what I always suspect though are long decay times every time I read fast or slow,and drivers that don't go very low don't excite as much,so... )

 

[dualazmak]

Is there a better term for describing the impression of 'fast" or slow" sounding woofers?

How about terms of "transient behavior" or "transient characteristics"?

I rather intensively measured "transient characteristics" of my woofers and subwoofers.
We can objectively see/observe the "transient characteristics" or "tightness of sound energy distribution" by using Adobe Audition's 3D sound color spectrum (Fq-Gain-Time).

Spoiler

- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495, #497, #503, #507

 

[dualazmak]

We're not talking about group delay i hope.

Agree. I did rather intensive measurements of time alignments for precise group delay tuning between subwoofers and other SP drivers.

Spoiler

- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-1_ Precision pulse wave matching method: #493

- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-2_ Energy peak matching method: #494

- Precision measurement and adjustment of time alignment for speaker (SP) units: Part-3_ Precision single sine wave matching method in 0.1 msec accuracy: #504, #507

- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495, #497, #503, #507

- Perfect (0.1 msec precision) time alignment of all the SP drivers greatly contributes to amazing disappearance of SPs, tightness and cleanliness of the sound, and superior 3D sound stage: #520

- Not only the precision (0.1 msec level) time alignment over all the SP drivers but also SP facing directions and sound-deadening space behind the SPs plus behind our listening position would be critically important for effective (perfect?) disappearance of speakers: #687

 

[Doodski]

How about terms of "transient behavior" or "transient characteristics"?
I rather intensively measured "transient characteristics" of my woofers and subwoofers.

Spoiler

- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495, #497, #503, #507

Sometimes the term dynamic range can be used. To have good dynamic range means to have a lifelike range and that would make the percussion sound faster and more accurate.

 

[gnarly]

It’s comes across as condescending when you make a comment that way. No one actually is making the claim that the “speed” is different since the speed of sound is fixed as is the frequency. Its like criticizing someone for calling food “hot” when the temperature is cold, but the person is using “hot” to describe “spicy.”

There is definitely a difference between fast and slow subwoofers, and it may be as simple as distortion or cabinet resonance.

Here’s a question. If I play back a 30 Hz tone for 3 seconds at 100 dB, I would expect my woofer to vibrate 90 times at some level of excursion to achieve that SPL. Imagine after the 90th oscillation I unplug the sub.

Are there scenarios where one woofer at the end of the test single oscillates one more time at a lower level of excursion and scenarios where another product oscillates twice and another that doesn’t oscillate at all?

I'm probably guilty of being a bit condescending as well...my bad, sorry. It's just the subs have speed idea is a hopeless rabbit hole it appears.....sigh...

Anyway, to your question..
First, the idea of cutting power is not a valid test concept.. The amp speaker work as a pair with the amp controlling motor oscillations.
Amp must stay on. Tone bursts with precise start-stop work for such a test.
Mic the acoustic output. REW, with its tone burst generator and scope capability make it pretty easy to do.

Even for a crappy driver, there would be no full period oscillations after the end of the burst, thatare anywhere close to the amplitude of the burst.