This came to my email. The post originated in RAC. I prefer to reply here as
well,
there are others that can help to answer and debunk the audio myths better
than I.

----- Original Message -----
From: "Les"
Newsgroups: rec.audio.car
Sent: Wednesday, May 19, 2004 6:30 PM
Subject: System I'm designing - two questions



"Aaron Russell" wrote in
message
...
a head unit without pre-outs? christ, that must be
ancient..

first off, if you want clean, tight bass, go with an
amplifier with a
damping factor of 500 or better.

BTW- Most supposed "audiophiles" usually say that 200 is enough.


Go with any modern amplifier. The damping factor is a
moot point nowadays
and is merely a gimmick marketing tool to show a big
number.

"with higher frequencies, thats true, its not largely
noticeable at
comfortable hearing levels, but with lower frequncies, it
is a drastically
noticeable difference. amps with much higher damping
factors have MUCH
better control of the woofers. I thought the same as you,
until I tested it
for myself last year, comparing side by side, US amps
DE-3000, and the
USA-3000 , both setup with the same head unit(pre-outs had
low-pass set to
100 Hz, all crossovers and subsonic filters disabled on the
amps, wired to
the same subwoofer configuration, 3000x1 watts @ 2 ohms,
and the gains were
adjusted on both amps until they outputed 130 dB at 40 Hz,
for testing
purposes. I tried to eliminate any varibles other than the
amps themselves..
anyways, the results were as follows: the DE-3000
(advertised damping factor
of 200) did NOT have NEARLY the amount of woofer control
that the USA-3000
(advertised damping factor of 2200), there was an amazing
difference in
woofer "tightness" and control, not really noticeable so
much when you'd
play straight test frequencies through it, but once it was
set, playing
highly bass reactive music through it, like speed metal and
various rap
tunes. anyways."


Let me see your data. Where are your measurments? It sounds like you relied
solely on looking at the woofer and listening. Both "tests" which don't hold
any water. It is the same snakeoil techniques that marketing people use to
get people to believe the myths anyway. You attempted to make your tests
valid, but without data and measurements it was all for not.


"the engineers over at US AMPS told me on
the phone it was
because of the high damping factor, and i choose to believe
them, since
thats what they went to college for."


You just called up US Amps and talked to the engineers? It seems highly
unlikely. Especially since if they knew what they were doing they would have
told you the truth about damping factor. I did some more research on damping
factors and relation to SQ. Here are some of my results. I found conflicting
websites, as I expected, and I noted one large difference between the 2
arguments. Those that are claiming the big SQ differences often had no data,
other than the type of "evidence" you provided, the rare couple that did had
virtually no explanation of how the numbers were acheived. Those that are
saying that the big number DFs were really meaningless usually provided
numbers, with explanations of how they are achieved, and most showed how it
actually related to the speaker. Which how it actually relates to the
speaker is important, and from what I have seen is overlooked by the Big
number DF camp. Naturally I could find sites that are the other way, this is
just generally what I found. (Yahoo search for "damping factor")

Here is a few articles.
http://www.trueaudio.com/post_013.htm

http://66.218.71.225/search/cache?p=...yc=10240&icp=1

http://otlamp.com/articles/tomcik/

This is one of those, that is kinda right, but never provides any basis for
the numbers achieved.
http://www.leecao.com/caraudio/amplifier.html

Now, a marketing blurb from my favorite pro sound amp company. (Notice no
data, only touting thier amps) I found that most amp manufactures claimed
that big number DFs are important, but most are like Crown and never provide
any hard data.
http://www.crownaudio.com/pdf/amps/136224.pdf



Signal to noise ratio doesnt matter so much
with bass frequencies, 95 dB or higher is fine.... if
it doesnt
advertise
what the damping factor is, then chances are its ****ty

Or they realize that every modern amp already has a high
enough rating and
there is no need to state it.

.. i personally never
really liek any of the JL amps for SQ, always thought
they sounded too
harsh, even when i had the Clarion DRX-9255 for a head
unit. you want
good
SQ for a cheap price? im sure theres plenty of people
that will argue
with
me on this, everybody has their opinions.. but The "low
profile"
Farenheit
series from Power Acoustik, which is now discontinued,
produced better
SQ
scores than my xtant, soundstream, or( i know im gonna
get **** for
this!)
my ESX quantum amplifier setup. actually.. the ESX
quantum amps( Q 175-2
and
Q120-4 )had a slightly softer tonal quality, BUT, it
distorted more at
higher volumes..


Where to start?? Aaron, let me ask you a question and
perhaps it will help
dispell the myth. How can the amps sound different?

"ohhh i dont know, different quality of crafstsmanship?
different quality of
components? different designs? they just sound different
bro."


They just sound different?? I don't think so.


"Ever compare a
tube amp to a solid state amp side by side? HUGELY
different sound. They
will look almost identical on an oscilloscope if adjusted
right, but they
will still each have a distinct sound."

Sorry, I really meant SS amps. I forget to mention that, but since 99% of
car amps are SS I thought it was an assumed.
There is also more than an Oscope. And Tube amps and SS amps usually do not
have thier specs within the threshold of human hearing.


When you measure then,
scope them, whatever and all the results come out with
differences below
the
threshold of hearing then how can they possibly sound
different?

"i dont know, you tell me, since you seem to have all the
answers,"


They don't. That is the answer. If you cannot measure a difference then how
can you hear it?? Some mythical fairy just makes amps sound different?


" go by
what my ears tell me.. Sure, if you had a 50 band EQ
attached to every amp
setup to get them to sound EXACTLY the same at a given
volume level, then
yes, id agree with you.."


That's the point. You don't need a 50 band EQ. Level match them, operate
them within their linear limits, then measure them. The differences, if any,
would be below the threshold of human hearing. The human ear is a remarkable
ineffiencient and inaccurate device. The point of the amps sound the same
argument for me is this, there are more important things to base a purchase
of an amp on.


When you operate an amp within it's linear limits, ie no
clipping, then
you
will not be able to hear a difference, especially in a
car.

"this is absolute nonesense..there's always differences that
are audible in
every audio setup..otherwise ALL quality amps would cost
the same because
there was no real difference between them, and there woudl
be no need for
audio competition."

Sure there a differnces in every audio setup. I never said there were not.
Amps don't cost the same because of several factors, not just the supposed
SQ. You are forgetting to price in quality, output power, features, and even
reputation. There are SEVERAL factors into determining the cost of an amp.
Your argument is becoming absurd.

Your ESX
distorted more at higher volumes because you were either
clipping it or it
was defective.

"nope, they were fine.. i had 4 of the same amp.. all
soudned the same."

Then you were clipping it, or possibly hearing something that wasn't there.

A softer sound is often associated with a lower volume. The
physics of the matter support the fact that they sound
the same, the I
heard
it argument is so full of holes it doesn't hold water.

"ummm, what else would you have to go by except what you
hear?"

Of course, the ultimate goal of a car audio system is to sound good to you.
But when you realize that there are not SQ differences in your amps it
allows you to focus your search on important features to make sure you get
the best amp for your situation. Then you can spend the money you saved by
not purchasing that "SQ" amp and buy those speakers that you really liked.

"and the
physics DO support that amps will sound different. These
amps dont all share
the exact same componenets, do they? HIGHLY doubtful."

They don't have to use the same components. Components can go into the
quality of the amp, but not really the SQ. Your logic is flawed. Physics
tells us that if we cannot measure the differences then HOW can we hear a
difference? There are not differences to hear. If there is nothing to hear,
then there is nothing to hear. Does that not make sense? Once someone from
the "amps sound different" camp can come up with something besides "I heard
it" or "They just does" then I might listen, for about a minute.

Les

They don't have to use the same components. Components can go into the
quality of the amp, but not really the SQ. Your logic is flawed. Physics
tells us that if we cannot measure the differences then HOW can we hear a
difference?

The laws of physics tell us that, in order for a difference to be perceived
by humans but NOT by the appropriate test equipment, one of two things must
be true:

1) The test equipment is not precise enough to compete with human sensation.
2) There is another component that cannot be measured that is at play here.
This would imply that another force is at work that has yet to be discovered
(ie. not gravitational, electromagnetic, weak, or strong forces).

(1) cannot be the case, because most test equipment generally used far
exceeds the thresholds obtained in human psychophysical experiments. The
amount of literature available in psychophysics in massive. It is a very
active field.

It must then be (2). So proponents of the notion that differences can be
heard but not measured are essentially claiming that the reason they cannot
measure differences is because the laws of physics are incomplete and that
this has profound implications in the realm of audio.

Call me skeptical.

MZ wrote:

It must then be (2). So proponents of the notion that differences can be
heard but not measured are essentially claiming that the reason they cannot
measure differences is because the laws of physics are incomplete and that
this has profound implications in the realm of audio.

But even what folks THINK they hear and cannot be measured can be
verified by blind comparisons.... Let them use their ears ONLY without
actually knowing what they are lstening to.. If they really can tell a
difference
they will be able to do so blindfolded using only thier ears...

Most of the time folks that think they can, CANNOT when really tested
this way... We condicted a cable test comparing 40ft of old nasty RCA cables
VS very very ($2000) RCA cables of a very short length (I choose very opposite
cables, VERY EXPANSIVE vs VERY CHEAP and VERY LONG vs VERY SHORT
and still not one of the salesmen in a very high end store could tell the
difference
with their trained ears...

Eddie

...still not one of the salesmen in a very high end store could tell the
difference
with their trained ears.

People insert mental bias when choosing electronics. I sit and chuckle every
time I read a review, either of home or car audio equipment, that claims one
amp is "warmer" than another or "cleaner" or "more impactful" than another. 6
months ago I might've believed this crap but I've done a lot of asking
questions and personal research (much of it on this NG) and I've found it be
B.S. I compared my $1,200 Denon reciever to other Denon units as well as pieces
manufactured by Pioneer, McIntosh, Sony, Theta and several others. I found that
I couldn't indentify a single audible difference that could be attributed to
the amps - even when comparing my unit to units costing $4,500 and more.