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

I have buyer's remorse and am trying to decide whether to pay the 25%
restocking fee or put my hopes in speaker break in. I know that about
1/2 the buying public believes in it, but does anyone with an
engineering degree believe in it?

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

hoarse with no name wrote:
> I have buyer's remorse and am trying to decide whether to pay the 25%
> restocking fee or put my hopes in speaker break in. I know that about
> 1/2 the buying public believes in it, but does anyone with an
> engineering degree believe in it?

I'd say if you are unhappy with your speaker purchase, no amount of
"break-in" will change things.

Be sure to examine the possibility that the speaker is damaged and
should be repaired/replaced under warranty. That is quite a different
situation than not liking the performance. What exactly is causing your
"remorse"?

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On Mon, 19 Sep 2005 11:36:55 -0700, hoarse with no name <no@spam.com>
wrote:

>
>I have buyer's remorse and am trying to decide whether to pay the 25%
>restocking fee or put my hopes in speaker break in. I know that about
>1/2 the buying public believes in it,

I wouldn't have thought 1/2 the buying public had even heard of it.
Is this a specific "buying public" that reads certain magazines?
(Arny, do you have an opinion here?) In that case I might be amazed
that ONLY 1/2 of the readers believe in it. They also believe in
speaker CABLE breakin, but you didn't ask about that...

>but does anyone with an
>engineering degree believe in it?

FWIW, I have something like 3/4ths of a degree, and a couple of
decades or so of work experience. It's been good enough for several
employers.
There's the idea of breaking in a woofer to slightly 'loosen' the
suspension, slightly lowering resonant frequency (so that after the
burn-in you can design the exact size cabint or make the exact length
port for it), but that likely won't substantially change the sound of
a speaker. If anything it would change the low end only slightly.
Your words "put my hopes in speaker break in" suggests that you
hope the sound of the speakers will change in a positive way if you
"run them" for a while. I wouldn't expect the sound to change at all.

Care to tell us what make and model these are?

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hoarse with no name wrote:
> 1/2 the buying public believes in it, but does anyone with an
> engineering degree believe in it?

What kind of engineering degree? <grin/> I believe in _listener_
break-in more than speaker break-in.

If you're thinking about paying more, how sure are you that anything
else is going to sound better in that room?

(If you're thinking you like the sound of your old speakers better, that
may be a different kettle of worms.)

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"Robert Gault" <robert.gault@worldnet.att.net> wrote in message
news:bXHXe.59915$qY1.17983@bgtnsc04-news.ops.worldnet.att.net...
> hoarse with no name wrote:
> > I have buyer's remorse and am trying to decide whether to pay the 25%
> > restocking fee or put my hopes in speaker break in. I know that about
> > 1/2 the buying public believes in it, but does anyone with an
> > engineering degree believe in it?
>
> I'd say if you are unhappy with your speaker purchase, no amount of
> "break-in" will change things.

Not necessarily true. What the reviewers call speaker "break in", is mostly
due to the listeners auditory system becoming accustomed to the sound, which
hasn't changed at all..
The other major factor influencing the sound is the room accoustics. You may
like to fix any problems there before writing the speakers off.

MrT.

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"hoarse with no name" <no@spam.com> wrote in message
news:no-1E6485.11365419092005@cnews.newsguy.com

> I have buyer's remorse and am trying to decide whether to
> pay the 25% restocking fee or put my hopes in speaker
> break in.

IOW, you're having a problem adjusting to the sound of your
new speakers.

Give it time, in a month you'll either really love 'em or
really hate 'em and you won't need any advice to make up
your mind.

>I know that about 1/2 the buying public
> believes in it, but does anyone with an engineering
> degree believe in it?

Speaker break in is a real-world, measureable effect. It
takes place in a few seconds every time a speaker is used
after an extended period of non-use. There's an AES paper by
David Clark from which I paraphrased this.

So, yes engineers believe in speaker break in, just not in
the sense you are probably thinking about.

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In <no-1E6485.11365419092005@cnews.newsguy.com>, on 09/19/05
at 11:36 AM, hoarse with no name <no@spam.com> said:

>I have buyer's remorse and am trying to decide whether to pay the 25%
>restocking fee or put my hopes in speaker break in. I know that about
>1/2 the buying public believes in it, but does anyone with an
>engineering degree believe in it?

I've experienced a few electrostatic designs that can take a day or two
to charge. I don't like to think of this as "Break In", because one
must go through this cycle each time the unit has been powered down for
a while.

By the way, did you listen to the speakers prior to purchase?

-----------------------------------------------------------
spam: uce@ftc.gov
wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13> (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

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In article <7kqui1tcn9utch5g96m9841guesauttn53@4ax.com>,
Ben Bradley <ben_nospam_bradley@frontiernet.net> wrote:

> Care to tell us what make and model these are?

I thought that adding a Polk PSW10 sub to my KEF C30s would improve the
sound. The KEFs sound better alone on music, though the Polk does well
with movies. With music the Polk sounds like a man impersonating a bass
while plucking imaginary strings and going "bvvvvv, bvvvvv, bvvvvv".

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

Think about how much temperature, humidity and barometric pressure change
the characteristics of air. Those things are more likely to have a changing
effect on a speaker's performance. Once you get the voice coils about as hot
as they will ever be in normal operation and you get your woofer to throw
about as far as it can, the speakers are broken in. I don't think this takes
any time at all. The only effect of the passing of time after this is aging
and degrading of the materials. We all know what foam rot is. It's not a
good thing. Many speaker systems are made with materials that are formulated
to be less susceptible to damage from time, oxygen and ultra-violet.

James. )


"hoarse with no name" <no@spam.com> wrote in message
news:no-1E6485.11365419092005@cnews.newsguy.com...
>
> I have buyer's remorse and am trying to decide whether to pay the 25%
> restocking fee or put my hopes in speaker break in. I know that about
> 1/2 the buying public believes in it, but does anyone with an
> engineering degree believe in it?

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

hoarse with no name <no@spam.com> wrote:
> In article <7kqui1tcn9utch5g96m9841guesauttn53@4ax.com>,
> Ben Bradley <ben_nospam_bradley@frontiernet.net> wrote:
>
>> Care to tell us what make and model these are?
>
> I thought that adding a Polk PSW10 sub to my KEF C30s would improve the
> sound. The KEFs sound better alone on music, though the Polk does well
> with movies. With music the Polk sounds like a man impersonating a bass
> while plucking imaginary strings and going "bvvvvv, bvvvvv, bvvvvv".

Ah, now that sounds like something blown, or a bad cabinet resonance. Could
also be something in the room resonating. Check your amp, move the sub
around in the room, and if that doesn't help, try to see if it's a physical
noise not being directly produced by the cone.

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On Tue, 20 Sep 2005 12:33:05 -0700, hoarse with no name <no@spam.com>
wrote:

>In article <7kqui1tcn9utch5g96m9841guesauttn53@4ax.com>,
> Ben Bradley <ben_nospam_bradley@frontiernet.net> wrote:
>
>> Care to tell us what make and model these are?
>
>I thought that adding a Polk PSW10 sub to my KEF C30s would improve the
>sound. The KEFs sound better alone on music, though the Polk does well
>with movies. With music the Polk sounds like a man impersonating a bass
>while plucking imaginary strings and going "bvvvvv, bvvvvv, bvvvvv".

In addition to the possibility of a defective sub, have you taken care
to set up and balance the sub with test signals and, possibly, a sound
level meter?

Kal

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

James Lehman wrote:
> Think about how much temperature, humidity and barometric
> pressure change the characteristics of air.

Okay, let's do just exactly that. Let's use weork of people
Beranek, Kinsler, Frey, Balckstok and others as our guide.

>From Kinsler and Frey (1) we learn that the velocity of
propogation in a gas such as air under normal conditions
goes as:

c = sqrt(y P0/p0)

where c is the velocity of propogation, y is ratio of
specific heats of the gas (for air, which is essentially
a diatomic gas, y = 1.402, and is largely independent of
temperature over the range of such where we'd want to do
our listening), P0 is the constant equilibrium pressure
of the gas, which at 0C is 1.103*10^5 Pascals, and p0
is the constant equilibrium density of the gas, which at
0C is 1.293 kg/m^3. This leads to a velocity of sound at 0C
of 331.6 m/s.

If we then explore the temperature dependency, as it effects
P0 and p0 (since we find that y is independent of temperature),
the result is that the velocity goes as the square root of
the absolute temperature, and this first expression reduces
to a temperature dependent form:

c = sqrt(y r Tk)

To quote from Kinsler:

"For most gases at constant temperature, the ratio of
P0/p0 is nearly independent of pressure: a doubling of
pressure is accompanied by a doubling of density of
the gas, so that the speed of sound does not change
with variation of density"

As can be found in Kinsler, Frey, Beranek and others, one
that over moderate distances and the audible frequency
range (say, less than 10 meters and at frequencies below
25 kHz), large changes in relative humidity have no significant
effect on the propogation of sound.

One can find, without much effort, other means of determining
the dependency on the "characteristics or air" temperature,
pressure and humidity to an equal degree of scientific rigor.
The conclusion is fairly straightforward:

Over the range of temperatures, pressures and humidities
one is likely to encounter in a home listening situation,
with the exception of the propogation velocity, ambient
conditions have no significant effect on the propogation
characteristics of sound.

Even is one then considers the propogation velocity, it
goes as the square root of absolute temperature. Consider
a range of 15C (65F or 288K) to 35C (95C or 308K), the
difference in propogation velocity is sqrt(308/288) or
about 3%.

Consider the context of what variations are likely to
be found: in addition to the small variation due to
temperature, pressure does NOT vary over a wide range
except in extraordinary circumstances (usually referred
to as "hurricanes" ), circumstances under which the critical
acoustics properties of air are rather unimportant.

Thus, it would seem that the ACOUSTIC properties of air one
might encounter is unlikely to cause any significant difference
in sound.

> Those things are more likely to have a changing
> effect on a speaker's performance.

The above summary analysis shows that this is very unlikely to
be the case. This prediction is quite well supported by actual
measurements.

> Once you get the voice coils about as hot as they will ever be
> in normal operation and you get your woofer to throw about as
> far as it can, the speakers are broken in.

In fact, much, if not most, of this "breaking in" recovers after
the speakers are left to themselves for a short period of time,
ofetn but a few seconds.

> I don't think this takes any time at all.

Maybe a few seconds.

FAR more likely is the environmental dependency of the mechanical
parameters of the drivers themselves. For example, one can easily
measure a 10% difference in the mechnical compliance of surrounds
of the same temperature range (15C to 35C) that acocunts for a mere
32% difference in propogation velocity. One can also observe that
the actual mass of pulp-based cone materials also changes to a
substantial degree over typical ranges of relative humidity (10%
to 90%). Just these observable parameter changes alone can account
for significant changes in loudspeaker performance. This is less
true for configurations such as so-called "acoustic suspension"
systems, where fairly large suspension compliance changes have
little effect on system performance, since the system's compliance
is dominated by enclosure compliance (the very definition of
acoustic suspension, in fact). For higher order systems such as
vented box, they are more critical and can lead to measurable
differences in performance.

But one also encounters 10-20% differences in a driver's
mechanical compliance from sample to sample just due to
manufacturing variations alone: mechanical complisance is one
of the most difficult to control parameters, especially of
woofers.

The conclusion that one comes to after exploring both the
theory and measuring THOUSANDS of speakers (as I have), is
that the claims of "break-in" are simply not well supported
by either theory or data.

To date, no one who has performed the obvious experiment of
comparing a new, out-of-the-box speaker to a broken-in
speaker has been able to reliably detect which is which
when the selection is based solely on listening to the two,
simply because no one has actually performed the experiment.
Indeed, the inevitable variations between individual samples
of "nominally identical" speakers would seem to complicate
the matter.

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

Perhaps someone should do a controlled study of many woofers tested brand
new, half of them used for a few years and the other half sitting in boxes
on the shelf.

This is pure imagination on my part, but I would think that the first time a
strong signal is applied to a woofer, fibers in the spider and slightly miss
placed bits of glue would crack or melt away. That might make a difference
between strong signal and week signal measurements.

It has always amazed me how a woofer will measure very nearly the same when
driven over a HUGE range of power. But I guess that's the nature of sound.
It is logarithmic on many scales.

James. )

> To date, no one who has performed the obvious experiment of
> comparing a new, out-of-the-box speaker to a broken-in
> speaker has been able to reliably detect which is which
> when the selection is based solely on listening to the two,
> simply because no one has actually performed the experiment.
> Indeed, the inevitable variations between individual samples
> of "nominally identical" speakers would seem to complicate
> the matter.
>

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On 20 Sep 2005 18:19:08 -0700, dpierce@cartchunk.org wrote:

>To date, no one who has performed the obvious experiment of
>comparing a new, out-of-the-box speaker to a broken-in
>speaker has been able to reliably detect which is which
>when the selection is based solely on listening to the two,
>simply because no one has actually performed the experiment.
>Indeed, the inevitable variations between individual samples
>of "nominally identical" speakers would seem to complicate
>the matter.

I recall that Paul Barton of PSB described just such an experiment in
an interview many years back. The experiment also included
measurements. My recollection was that there were small differences
in measurements but the speakers were not audibly distinguishable.

Kal

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On Tue, 20 Sep 2005 12:33:05 -0700, hoarse with no name <no@spam.com>
wrote:

>In article <7kqui1tcn9utch5g96m9841guesauttn53@4ax.com>,
> Ben Bradley <ben_nospam_bradley@frontiernet.net> wrote:
>
>> Care to tell us what make and model these are?
>
>I thought that adding a Polk PSW10 sub to my KEF C30s would improve the
>sound. The KEFs sound better alone on music, though the Polk does well
>with movies. With music the Polk sounds like a man impersonating a bass
>while plucking imaginary strings and going "bvvvvv, bvvvvv, bvvvvv".

You might be playing the Beatles song "I Will."