Over the last few years electronic devices have produced some impressive
sounds from a tiny crappy looking almost-flat speaker.
For example, many cells phones have a "no hands" mode where the tiny
speaker easily projects the sound for several yards.
Another example is my USB memory device which can also play music. The
sound is not hi-fi but its very impressive for such a tiny speaker.
How the heck is this done?
(1) Is it done by better components like stronger magnets, stiffer cone
materials, longer or shorter(?) throw voicecoils, etc.
(2) Is it done by acoustic processing (like SRS Labs's "WOW!") but I
don't think that was so available a few years ago when the better
speakers started showing up.
So how is it done?
Hello, and I have witnessed the same thing. The perhaps unexpected volume
and fidelity can be attributed to speaker design/quality, enclosure
acoustics and speaker siting within the enclosure. Capability does not
always correlate to bulk. There are small high-end audio bookshelf and
pedestal-mounted speakers whose performance equals or excceds that of
their larger brethren. Even a low to middle end producer like Bose has
done some impressive things with their "acoustic waveguide" design.
Granted these transducers are larger than that found in hand-held
equipment. Signal processing such as Dolby NR can certainly provide
enhancement although I'm uncertain as to what is used in cell phones. I
would expect acoustic signal processing to be applied more in a device
designed to reproduce music.
Another acoustic/psychoacoustic phenomenon relating to fidelity that comes
into play is that of the "missing fundamental" (you can Google for further
into). Which is why some of us still remember getting decent rock and
roll sound from shirt pocket sized AM transistor radios. Sincerely,
John Wood (Code 5550) e-mail: firstname.lastname@example.org
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337
Sounds like the 'Bass Maximiser' in the Hyperprism DirectShow effects,
which transfer energy from the fundamental to the harmonics. It's not
exactly missing, it's just reduced relative to the harmonics, which our
hearing infers the fundamental from. I think it's a horrible effect. A
better way to get more bass energy to be perceived is to tighten the
envelope decay, so you stll need more bass handling capacity, but only for
short pulses. Even if the decay drops back sharply before an extended fade,
we still hear it as if it was full. That trick might not be used in mobile
phones, but it's definitely been used in radio to get a solid rock sound
from a small radio.
No it's about the other parameters of proper design.
A speaker housing and entire device cabinet that doesn't
resonant. An amp circuit that can provide the necessary
current without severe distortion. A speaker that can
likewise handle it.
Many simply thought the size of the speaker was the main
criteria when it is simply that small speakers are also more
commonly very cheap ones. Someone could make a really low
quality larger speaker, put it in a terribly resonant
cabinet and drive it will too low a wattage amp and it too
would sound terrible... though tend to have more bass.
No again. >:) He's right.
There are two diverging methods now. You're talking about the pure form,
the striving for true hi-fi, where basic techniques are refined.
THis thread isn't about that though. It's about how speakers small enough
to have no chance of rendering real air moving capability without shaking
themselves to brittle fatigued pieces, mounted in tiny sealed baffles that
couldn't accept such movements without developing deap-sea pressures even
if such air movemnt were possible from those little speakers, can still
somehow produce good bass. All kinds of non-purist tricks must be used.
Actually, some of those tricks should be used even by the purists. The mani
one being panning and balance set by delay and not only by varing the
signal level. Try it with a flanger effect, set the feedback to zero,
modulation off, and adjust the sub-millisecond delays slowly to afect an
already-panned signal. This simulates the tiny delay our heads cause to
incoming sounds (That's what the 'head related transfer functions' thing is
about, btw). This, combined with subtle low-pass filtering, can make a
signal pan well beyond the speakers.
There are several reasons why such tricks are not used in purist hi-fi:
1. Expense. Until recently, it's been prohibitive.
2. Subjectivity. The delay needed to make a degree of panning depends on
ear and head shape.
3. The effect has been used as a gimmick, and has got a bad reputation in a
If I were designing a balance control for hi-fi based on this I'd have a
main balance control that had a couple of smaller controls beside it, one
for filter, one for delay. To set it up, pan main hard left, then adjust
delay for making the sound go to best extreme for proper location left for
whoever is going to listen. Check it again on the right, then use the main,
then adjust the filter till it feels right. It's more complex than the
usual set of controls, but not much. It's no good setting up digital
poresets, a thing like that has to be as hands-on as the controls we've got
used to over decades.
Not sure whether the bass enhancement thing counts so well for hi-fi use
though. It might in active speakers though, where the aim is to match the
power gain stage with the transducer to air coupling. When you have that
much control over the output device, it probably can get hi-fi results for
a small bookshelf system.
An extra point:
If you can try that flanger experiment, set the amplitude on each channel
the same. :)
What's amazing about this, is the delay part of the panned signal can place
the location further left without level difference than the level
difference can do without the delay, even when the level is full in one
channel and ABSENT in the other!
That should be enough to convince you. But you'll have to do it. Don't just
take my word for it.
I'll take your word for it, because I will always be a
purist and never wish for any digital REprocessing of the
I built my own headphone/pre/power amps from scratch though,
I'm pickier than most.
Actually I don't either. :) No tone controls, only gain, and two Mackie
HR828's (active near/mid-field monitors).
Where those effects really help (and where I learned about them) is in
making music. When you use the delay panning carefully you can make very
subtle stereo effects that are musically expressive, especially when using
noises, close mic'd or ambient, as a source.
The delay panning isn't that bad an idea for general use though, if you've
ever experimented with binaural stereo (a long-standing interest for many
purists) you'll have already used it. As binaural stereo hasn't taken hold
because it's too dependent on head and ear contours, it would have to have
the kind of controls I suggest to make it useful to all. Not sure how this
could be used to vary the delays in a stereo mix though, unless it be based
on splitting the signal into several narrow bands and rebuilding to get the
wavefronts aligned. There is a tool that does this, a BBE something, used
to clarify poor phase in final mixes. That might be adapted effectively,
but I haven't tried one so I have no idea.
About lack of bass, even these Mackies don't go down to the lowest octave,
and it doesn't bother be, our hearing can enhance the fundamental without
preprocess, so long as there's enough info to start with. By definition,
missing the lowest octave means that ONLY the fundamental of those notes is
actually 'missing'. :) And it's only attenuated a bit.
Um, typo, HR424.. No such thing as HR828 as far as I know..
Also, the reason I don't use tone controls isn't beased on the idea of them
degrading the pure signal, it's purely that I get used to a sound in a
room. If I want to get the balance I don't adjust them except in the
crudest and most temporary situation. In stead I play some things I know
really well, and shift things in the room if there's some horrible boom in
a corner or something.
Apparently you have connected to another of those flawed interfaces
to usenet. This is not a forum. Be aware that a complete world
awaits you when you install a newsreader and connect to your ISPs
newsserver. I suggest you try Thunderbird, from mozilla.org.
Totally free, and available for many systems, including Windoze,
Mac, Unix/Linux, etc.
"If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
I'm using X-News, a Windows client. I'm not entirely missing the point. :)
It's just that I get careless with typing at times, trying to keep up with
a thought, and I miss typos and can't edit after posting. It used not to be
a problem but I think my sight might slowly be failing.
I know it's technically possible for usenet to allow deletions, and
possibly edits, but I think most systems don't allow it because it's easily
I'll look at Thunderbird though, as X-News has some ghastly OS-crashing
habits. Not that Firefox isn't free of GUI-affecting memory leaks, so
Thunderbird might not be a guaranteed improvement over X-News if it uses
common code with Firefox.
All of which is far too much off-topic info, but it might help people avoid
making assumptions. :) Sorry, hard to resist that one..
On a sunny day (Fri, 12 May 2006 05:10:23 -0400) it happened kony
What system, i am curious, electrostatic, dynamic, dynamic wit ha coild in teh
I once build a smal ldynamic one.... when you find you need permanent magnet
Also did some experimenting with piezzo.
Is yours betetr what you can buy commercially? (mine was not).
/pre/power amps from scratch though,
Yes done that too.
Na I am not, listening on PC speakers to my music now:-)
My MSI motherboard has a Realtec AC97 six channel sound system. There
is a built in demo which uses delay plus volume to "move" a sound
source. Now that everything has gone digital it's much easier to
implement this sort of thing. I can recall experimenting with screen
door springs with phono pick-ups attached, to simulate audio delay.
Made some interesting sounds, but hardly hi-fi!
Virg Wall, P.E.
Nor is 2-channel stereo. But it's a convention we've come to accept.
Actually, many sounds are processed with delay panning to set a realistic
position. WHile it's possible to overdo it, rendering the effect weird for
all but the largest ears and heads, there's nothing wrong with doing it in
moderation, it just means that those with largest ears and heads will hear
it slightly narrower field than most.
The one thing that gets to me about the purist thing is that I've seen
people worry about silver speaker cables, or the tiniest differences in an
MP3 encoding process, and various other things, when the differences in the
musicl process, or the final mix, or even a bit of EQ on the stereo mix,
all make far more bold changes to the sound. If it sounds good, people will
accept is hi-fi, so long as they don't see that crude assembly of signals
at their end.
If you want a great take on that whole thing, listen to a song by Micheal
Flanders and Donald Swann. >:) It's called 'A Song Of Reproduction'. It
encourages a healthy wariness of too much narrow refinement. The reason why
such things as big sounds out of tiny speakers are amazing people right now
is that it's taken the computer industry to shift people's perceptions far
enough and fast enough to make it possible to try things which have
actually been commercially and technically possible for decades. It's the
limited concept of what is 'hi-fi' that has had to break down first.
People can agrue till death about how hi-fi is simple, only to reproduce
the original sound, but it can't. No two-channel system can. Which is the
point, The only way out of a circular argument is to accept new ideas into
The answer is easy, the goal is not "bold changes", it's
accurate reproduction. Some will psychologically err when
they assume their further tweaking of audio cables sounds
better without an ABX test but even that isn't valid-
because multiple changes below a threshold of discrimination
(taken alone) can sum to a perceivable difference.
Audio is so subjective though, it's fairly impossible to
generalize that "people will accept is hi-fi" when talking
about all the possible variations. Even a crude $3 AM radio
sounds pretty good compared to silence but set it next to
something better... so ignorance can be bliss, the road to
perfect sound is long and winding.
Those who do the most critical listening seem to disagree
and prefer 2 good channels over digitally mutilated sound.
There's nothing wrong with digital at all, to preserve, not
change the sound.
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