[regsaudioforum] Re: Dipole bass "punch"?
- Forget classical music for a minute. Those who doubt the reality of bass punch perhaps need to remember events from their mis-spent youth. Remember listening or dancing at a rock concert or club where the loud bass from the drumkit or electric bass seemed to sock you in the gut? You KNOW this effect exists live. If you don't, you've been living a very sheltered life indeed for the last 50 years. It existed for live rock bands back when I was in high school in the 1960s when bands were using early Sun and Fender amps. I remember one dance affair where the stomach and testicle massage from the purring/pulsing electric bass from the Sun amps in use made me queasy and the gut punch from the drumkit only made matters worse.
If it doesn't seem to you to exist on recordings, there are reasons other than dipole/non-dipole which could prevent you from experiencing this effect, among them: The recording is intentionally made bass weak. The playback is bass weak. Or your playback is not loud enough to produce the effect heard at live musical events.
>>> "tonycdk" <tcdk@...> 5/1/2009 1:08 AM >>>After reading the various responses it would seem that "bass punch" is an audiophile item - not present in most recordings but nice to listen to. It appears that room resonance build-up and/or boosted mid bass (relative to the low bass)are responsible.
I have put a subwoofer measurements pdf in the files section, with the thought that somebody might find it of interest.
--- In firstname.lastname@example.org, "Robert Greene" <regonaudio@...> wrote:
> Just to be clear here:
> At a given power level input(electrically), the
> steady state response in the room tells you how much total acoustic power output the speaker has at that input level and whatever frequency is being measured.
> The steady state response does not tell you what the "shape" of the output is over time to a given impulsive level.
> Logically, "punch" would be associated to an impulse input producing a very concentrated signal (in time) as output. However, as we were discussing, the audible "punch" impression may be produced by having the bass parts of the signal reduced in level.
> Now returning to the literal behavior of bass: In a minimum phase system(which speakers usually are in the bass, even if they are not so necessarily in-room, as UB demos), the amplitude response determines the phase/time response. For example, the bad "overhang" of crudely designed bass reflex boxes is associated to a peak in response at the "one note" bass frequency. In a well-designed bass reflex system, the response is smoother/flatter and has no big rise in response at any one frequency. But the phase behavior is still different from a sealed box because the deep bass rolloff rates are different, and response differences affect phase behavior not just where the responses are different but everywhere else(in the frequency range).
> This is especially true upwards: how the deep bass rolls off determines the phase response in frequency ranges considerably above the bass(in principle, all the way up but the effect diminishes farther up).
> Thus a sealed box with its 12 dB per octave roll off(final slope) is
> other things being equal going to have different (and usually better, other things being equal) phase response further up than the (usually) 24 dB per octave of vented enclosures.
> One should note however that these things are quite complicated in detail with the various "alignments" related box size, woofer free air resonance, mass versus stiffness control and so on. This is not a simple minded subject!
> It is also important to note(along the lines of the effects dininishing as one goes up in frequency) that a ported speaker with a very low frequency port tuning starts to be like a sealed box as far as behavior up higher goes. A ported box tuned to 20 Hz sounds a lot like a sealed box if one is listening to frequencies of say 150 Hz. The phase effects on the higher frequencies gradually go away.
> It is interesting to look here for an alternative view of the importance of "transient behavior'
> Anyway, the spreading over time of transient-inaccurate systems, the ringing after an impulse as such, is attached to response irregularities. It is just attached in a complicated way.
> We have talked before about the KEF experiments of extending deep bass response WAY down --and the demo of adible effect far up in frequency. (EQ to flat to 5 Hz, audible effect in material with nothing below 40 Hz etc.)
> --- In email@example.com, robert jorgensen <robert.jorgensen@> wrote:
> > I think Russels is very close to the crux of the matter. Time and
> > especially energy over time does matter.
> > The total amount of energy in the speaker/room system and its release
> > over time must have a large influence on the perception. Obviously a
> > system where a significant amount of energy is output after the input
> > has stopped will sound heavier (louder) than a system where the output
> > stops sooner.
> > This is not just a matter of the type of cabinet and the system it
> > forms with the speaker unit(s). It involves the system which adds the
> > room is which we are playing.
> > Robert in spring-like Brussels
> > On Wed, Apr 29, 2009 at 2:23 AM, Russell Dawkins <rdawkins@> wrote:
> > >
> > >
> > >
> > > Since reflex boxes rely by definition on resonance to supplement direct
> > > output from the driven element to achieve flat response in the nether
> > > regions, wouldn't that slow the settling time? Wouldn't the output that is
> > > surplus to the input constitute the part of the output that is the speaker
> > > "singing along", and wouldn't this contribute to the perception of more
> > > output in that region - even "punch"?
> > > To re-state, if a bass reflex and a planar speaker, both of which measure
> > > flat with a nearly steady state signal but one having a faster settling time
> > > than the other, are judged with a music signal, the latter will seem
> > > deficient in the bass because the fast settling time actually results in
> > > less output in the bass.
> > > Please excuse the clumsy wording!
> > >
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- Undoubtedly your experience, noted below, was entrancing. But it doesn't
quite suggest that the world would be better off if all of his amplified
work was discarded.
I've got a copy of Ella Fitzgerald's "The Intimate Ella" with just her
and a solo piano. It is simply wonderful, but it doesn't eliminate the
fact that I also love her work in front of a big band. And my large
collection of rock music isn't going anywhere, either.
One can draw endless analogies in other areas. The fact that there are
some wonderful, very simply made films doesn't preclude big-budget
movies with grand special effects from also being a very enjoyable
experience. I'm glad we have both.
Take any art pursuit - one can always argue that there is too much of
one type and not enough of another, but the world has always been full
of fads and fashions of the moment that leave a certain segment of the
population scratching their heads.
On Sat, 2009-05-09 at 03:05 +0000, Robert Greene wrote:
> This is surely a valid point, but perhaps not quite as much as it
> appears. I recall hearing Lightnin' Hopkins in Carnegie Hall.
> He was on some occasions inclined to extreme amplification, but this
> time he was "unplugged", as people came to say later.
> He came out with an acoustic guitar, sat down a little stool,
> and played and sang rather quietly and intimately some blues songs in
> the old style.
> This was one of the greatest concerts for sheer emotional impact I
> have ever heard. People settled into a trance, sitting absolutely
> still and listening carefully for every note and every word and
> inflection. It was soft--but the effect was overpowering.
> I think the effect was much greater actually than if he had sung into
> a mike and had a mike on his guitar to produce more "normal" volume
> Of course, circumstances alter cases, but this was an instance where
> even in a large venue--and Carnegie seats 2800 or so-- an intimate
> performance worked its magic.
> This was in the 1960s. Would people put up with this today?
> Perhaps not. But I can promise you that everyone there felt not that
> they had been imposed upon but rather that they had experienced
> something magical. When the concert was over, there was a moment's
> pause while the audience returned to earth. Then there was an enormous
> ovation that went on and on and on.
> --- In firstname.lastname@example.org, Mitch Smith <mitch@...> wrote:
> > One also needs to keep in mind that a wide range of non-classical
> > couldn't even exist without amplification.
> > Take the "intimate" style of jazz singing that started becoming
> > in the 1930s with the advent of PA systems. Think of a singer
> > with a good size jazz band behind them - you'd never hear the singer
> > without the PA. They'd have to sing in a completely different style
> > be heard.
> > While the goal of the jazz singer is to sound "natural", the volume
> > balance between them and a large band requires a PA.
> > While I love completely acoustic music as much as anyone, I wouldn't
> > want to do without the Ella Fitzgeralds and Sarah Vaughans of the
> > or their modern counterparts. Ella with a vaudeville or opera voice
> > isn't quite the same.
> > In many ways a recording of this kind of music can be preferable to
> > live performance at a large venue with a mediocre PA.
> > - Mitch
> > On Fri, 2009-05-08 at 12:43 -0500, Tom Mallin wrote:
> > >
> > >
> > > The reality Rob points out is an example of why restricting the
> > > definition of "concert" to an unamplified public musical
> > > isn't practical. Outside the classical music genre (and I'll throw
> > > into that genre the rest of the repertoire typical of community
> > > chorus, band, and orchestra performances), which accounts for much
> > > less than five percent of publically performed music by any
> > > you care to use, unamplified public musical performances are
> > > exceedingly rare these days, and getting rarer all the time. Rock,
> > > pop, and broadway stuff is mostly all amplified. The same is true
> > > folk and small jazz combo music. Occasionally you can find a large
> > > jazz band playing without amplification, but even that is getting
> > > rare.