Some technical questions on speakers ?

Archived from groups: rec.audio.tech (More info?)

I was looking at the specs on speakers and was not certain what some
of the specifications mean.

The speaker has a sensitivity of 88db. Is a high sensitivity a good or
bad thing?
.. Does a high sensitivity mean that the speaker can work at a very
low volume?
The material of the some speakers are Aramid Fibre, Keviar HOP, paper,
etc. Which would be the better material for a speaker?
Some subwoofers are Bass Reflex or Closed Cabinet. Which is better?
What is Bi-Wiring Connection Capability and does it improve the sound
of the speaker?
Is a 25mm carbon composite dome better than a 25mm Balance dome for
sound?

Would there be much improvement in a 30mm sub woofer speaker compared
to a 20mm sub woofer speaker? (this is the speaker size) to be used
in a small room

Regards Brian

Archived from groups: rec.audio.tech (More info?)

"Stewart Pinkerton" <patent3@dircon.co.uk> wrote in message
news:fsvr51lfidfmacdqdht992c7iai0fg6o72@4ax.com...
> On Thu, 14 Apr 2005 16:15:57 +1200, Brian <bclark@es.co.nz> wrote:
[snip]
> It has to provide less excursion for a given volume at any
frequency,
> and I am not aware of *any* really good sub which uses a 200mm
driver.
> I took the liberty of presuming that you meant 300mm and 200mm, as
> your actual figures would be tweeters! :-)
> --
>
> Stewart Pinkerton | Music is Art - Audio is Engineering

Pinky as ever, dead on.

To enlarge on the comment above, bass is all about moving air in large
quantities. Thus it follows that a small driver - as small as 110mm -
used in some designs will have to have a very long excursion
capability to achieve the same volume of air movement (or at least air
activation) as a driver twice or three times the diameter. The
mechanical constraints of the cone mounting usually mean that the
further the cone moves the less linear that movement becomes and by
definition the sound produced becomes distorted. Conversely a large
cone does not have to move anything like as much to activate the same
volume of air, so given a good and compliant mechanical mounting the
sound produced should be 'better' - especially as the input frequency
gets lower.

Having said that, and before anyone (PInky included) flames me, the
larger cone will have considerably more mass than the smaller cone and
will thus need both more energy and (significantly) more time time to
get it moving and for it to stop moving afterwards. The result will be
a tendency to 'smearing' of the bass sounds and a loss of what the
magazines call 'kick' or 'punch.'

In the final arguement, the choice of design depends on how you want
to use the driver and for what purpose. If you want surround sound
from films etc then I think many would say that a sub-woofer with a
big driver should be your choice as the bass from such tends to be
over-done for effect and has little connection with musical reality.
Similarly if you want to play pop or rock at high levels then a
sub-woofer or an integrated speaker with a big bass unit would
probably be best as at high volumes you loose the ability to hear the
low frequency definition due to selective hearing attenuation by you
brain*. If on the other hand you are in a small room and want to
listen at more normal (i.e. lower) levels and the music detail - as
perhaps in jazz - is important, then a good integrated speaker design
(i.e. all the drivers in one box) with a smaller bass/mid unit may
suit you better, even though it may be a little lacking on the deepest
bass notes.

*(Ever noticed that if you sit stationary in the car with music on, it
sounds quite good and has reasonable or even plenty of bass, but when
you are moving, apart from perhaps having to increase the volume a
little, the bass levels seem to drop? This is because there is
considerable local low-frequency noise interference in the car -
engine noise, tyre/road rumble, etc - which is in the same audio band,
so your brain tends to selectively switch off to that noise and you
loose the musical bass in the process. The same will happen with loud
music, that your brain will adjust to the highest component level and
attenuate to that, and as that will be at higher frequencies (than
bass) you will loose bass definition. At a rock concert you often only
really know that the bass is still there in power because you feel it
rather than hear it.)

In the end it is all down to compromise and personal choice. At worst
listen before you buy - preferably to your own discs that you know
well - at best get a home trial.

OK all (Pinky included) - do your worst and flame me to your heart's
content - this is just my personal opinion.


--
Woody

harrogate2 at ntlworld dot com

Archived from groups: rec.audio.tech (More info?)

Brian wrote:
> I was looking at the specs on speakers and was not certain what some
> of the specifications mean.
>
> The speaker has a sensitivity of 88db. Is a high sensitivity a good
or
> bad thing?

It can be a good thing, because it means you don't need such a
powerful amplifier to produce a given amount of loudness.

> Does a high sensitivity mean that the speaker can work at a very
> low volume?

It doesn't matter. Any speaker that works at high volumes will work at
low volumes.

> The material of the some speakers are Aramid Fibre, Keviar HOP,
paper,
> etc. Which would be the better material for a speaker?

Whatever a good designer chooses. When you start asking too many
questions about how a speaker is made, you're second-guessing the
designer. You are well-advised to judge speakers based on their
performance, more specifically the sound quality.

> Some subwoofers are Bass Reflex or Closed Cabinet. Which is better?

See former comments about trying to second-guess the designer.

> What is Bi-Wiring Connection Capability and does it improve the
sound
> of the speaker?

Absolutely not.

> Is a 25mm carbon composite dome better than a 25mm Balance dome for
> sound?

See former comments about trying to second-guess the designer.


> Would there be much improvement in a 30mm sub woofer speaker
compared
> to a 20mm sub woofer speaker? (this is the speaker size) to be used
> in a small room

See former comments about trying to second-guess the designer.

Archived from groups: rec.audio.tech (More info?)

On Thu, 14 Apr 2005 07:14:11 GMT, "harrogate2"
<harrogate2@ntlworld.com> wrote:

>To enlarge on the comment above, bass is all about moving air in large
>quantities. Thus it follows that a small driver - as small as 110mm -
>used in some designs will have to have a very long excursion
>capability to achieve the same volume of air movement (or at least air
>activation) as a driver twice or three times the diameter. The
>mechanical constraints of the cone mounting usually mean that the
>further the cone moves the less linear that movement becomes and by
>definition the sound produced becomes distorted. Conversely a large
>cone does not have to move anything like as much to activate the same
>volume of air, so given a good and compliant mechanical mounting the
>sound produced should be 'better' - especially as the input frequency
>gets lower.
>
>Having said that, and before anyone (PInky included) flames me, the
>larger cone will have considerably more mass than the smaller cone and
>will thus need both more energy and (significantly) more time time to
>get it moving and for it to stop moving afterwards.

Only partially true. While the larger cone may have more mass, it will
also have a more powerful motor, and stiffer suspension (given equal
Fs and sensitivity).

> The result will be
>a tendency to 'smearing' of the bass sounds and a loss of what the
>magazines call 'kick' or 'punch.'

No it won't, given equality as noted above. The old myth of using
several small drivers because they are 'faster' is just that - a myth.

The tightest (and deepest) bass I've ever heard comes from a subwoofer
system which uses two 15" drivers, but has a Qts of 0.65. Most
commercial 'box' subs have Qts of at least 0.8, and often more than 1.

What the magazines call 'kick', 'punch' or 'slam' has *much* more to
do with peaking up in the 60-80 Hz region. What you think of as
'speed' in this context is almost entirely concerned with Qts, and
this is a *system* design matter, not just a driver function.


>OK all (Pinky included) - do your worst and flame me to your heart's
>content - this is just my personal opinion.

So don't make 'factual' claims! :-)

--

Stewart Pinkerton | Music is Art - Audio is Engineering