| Author |
Message |
mpresley
Guest
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 Posted:
Sun Oct 23, 2005 9:47 pm Post subject:
FR speaker question |
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Perhaps someone here could answer my question. I was looking at the
following speaker
http://jbl.com/home/products/product_detail.aspx?prod=L830&cat=SLS&ser=SLS
at the JBL website. The titanium tweeter is crossed over to a HF horn
loaded mylar dome. The crossover frequency is said to be 20KHz, and the
response is said to run to 40KHz.
What is the reason for this driver? What kind of usable audio material
could possibly be up there at those frequencies? Since CD will cut off
at 22KHz, and since few (other than young people) can hear anything even
approaching 20KHz, is this something that is warranted? Is it just
technical "I can do it" excess? Is it just marketing? Or is there some
actual real world benefit to this kind of FR in a speaker?
Thanks for any comments in advance.
mp
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Chung
Guest
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| Posted:
Mon Oct 24, 2005 7:49 pm Post subject:
Re: FR speaker question |
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mpresley wrote:
| Quote: | Perhaps someone here could answer my question. I was looking at the
following speaker
http://jbl.com/home/products/product_detail.aspx?prod=L830&cat=SLS&ser=SLS
at the JBL website. The titanium tweeter is crossed over to a HF horn
loaded mylar dome. The crossover frequency is said to be 20KHz, and the
response is said to run to 40KHz.
What is the reason for this driver? What kind of usable audio material
could possibly be up there at those frequencies? Since CD will cut off
at 22KHz, and since few (other than young people) can hear anything even
approaching 20KHz, is this something that is warranted? Is it just
technical "I can do it" excess? Is it just marketing? Or is there some
actual real world benefit to this kind of FR in a speaker?
Thanks for any comments in advance.
mp
|
Perhaps their titanium tweeter has a noticeable droop in the last octave
(10KHz - 20KHz), and crossing over to the ultra-high frequency tweeter
flattens the response up to 20 KHz?
The fact that the cross-over is at 20KHz means that there is significant
contribution from both drivers in an octave or so around 20KHz,
depending on the order (steepness) of the cross-over. A speaker guru
like Dick Pierce may have a better explanation, though.
Of course, there is probably marketing specsmanship here, too. |
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Guest
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| Posted:
Mon Oct 24, 2005 7:53 pm Post subject:
Re: FR speaker question |
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The frequency response of Super audio CD (SACD), the new format
developed by Sony and Philips extends out to around 100 KHz - so there
is a source available that can exercise this extended high frequency
performance.
Many instruments produce harmonics well beyond 20KHz. For example a
Trumpet with Harmon mute produces harmonics as high as 80Khz; a French
horn, 90KHz. 40% of the power in a cymbal crash is represented by
frequencies above 20KHz. These figures are taken from a paper titled
"There's Life Above 20 Kilohertz! - A Survey of Musical Instrument
Spectra to 102.4 KHz" by James Boyk available at
<http://www.cco.caltech.edu/~boyk/spectra/spectra.htm>
Boyk does not express an opinion on whether this high frequency energy
is perceptible. He does cite a result reported by Oohashi - who
recorded a gamelan (an Indonesian percussive gong chime orchestra) "to
a bandwidth of 60 kHz, and played back the recording to listeners
through a speaker system with an extra tweeter for the range above 26
kHz ... The experimenters found that the listeners' EEGs and their
subjective ratings of the sound quality were affected by whether this
"ultra-tweeter" was on or off, even though the listeners explicitly
denied that the reproduced sound was affected by the ultra-tweeter, and
also denied, when presented with the ultrasonics alone, that any sound
at all was being played."
Who knows?
rotor451 |
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Harry Lavo
Guest
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| Posted:
Tue Oct 25, 2005 4:42 am Post subject:
Re: FR speaker question |
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"Chung" <chunglau@covad.net> wrote in message
news:djisa60bu1@news3.newsguy.com...
| Quote: | mpresley wrote:
Perhaps someone here could answer my question. I was looking at the
following speaker
http://jbl.com/home/products/product_detail.aspx?prod=L830&cat=SLS&ser=SLS
at the JBL website. The titanium tweeter is crossed over to a HF horn
loaded mylar dome. The crossover frequency is said to be 20KHz, and the
response is said to run to 40KHz.
What is the reason for this driver? What kind of usable audio material
could possibly be up there at those frequencies? Since CD will cut off
at 22KHz, and since few (other than young people) can hear anything even
approaching 20KHz, is this something that is warranted? Is it just
technical "I can do it" excess? Is it just marketing? Or is there some
actual real world benefit to this kind of FR in a speaker?
Thanks for any comments in advance.
mp
Perhaps their titanium tweeter has a noticeable droop in the last octave
(10KHz - 20KHz), and crossing over to the ultra-high frequency tweeter
flattens the response up to 20 KHz?
The fact that the cross-over is at 20KHz means that there is significant
contribution from both drivers in an octave or so around 20KHz, depending
on the order (steepness) of the cross-over. A speaker guru like Dick
Pierce may have a better explanation, though.
Of course, there is probably marketing specsmanship here, too.
|
Or perhaps someone at JBL found that the super-tweeter adds a slight bit of
"airiness" to the sound or improved the transient response of the speaker. |
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Steven Sullivan
Guest
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| Posted:
Tue Oct 25, 2005 4:42 am Post subject:
Re: FR speaker question |
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rotor451@optusnet.com.au wrote:
| Quote: | The frequency response of Super audio CD (SACD), the new format
developed by Sony and Philips extends out to around 100 KHz - so there
is a source available that can exercise this extended high frequency
performance.
|
or, perhaps , that 'performance' is to act as a sink for the
pointlessly extended high frequeny input, to avoid having the audible
range mucked up in the rest of the drivers.
| Quote: | Many instruments produce harmonics well beyond 20KHz. For example a
Trumpet with Harmon mute produces harmonics as high as 80Khz; a French
horn, 90KHz. 40% of the power in a cymbal crash is represented by
frequencies above 20KHz. These figures are taken from a paper titled
"There's Life Above 20 Kilohertz! - A Survey of Musical Instrument
Spectra to 102.4 KHz" by James Boyk available at
http://www.cco.caltech.edu/~boyk/spectra/spectra.htm
Boyk does not express an opinion on whether this high frequency energy
is perceptible.
|
Which point *does* rather matter, doesn't it? After all, we
are constantly bombarded with visual 'input' that is simply filtered
out before it reaches the brain.
| Quote: | He does cite a result reported by Oohashi - who
recorded a gamelan (an Indonesian percussive gong chime orchestra) "to
a bandwidth of 60 kHz, and played back the recording to listeners
through a speaker system with an extra tweeter for the range above 26
kHz ... The experimenters found that the listeners' EEGs and their
subjective ratings of the sound quality were affected by whether this
"ultra-tweeter" was on or off, even though the listeners explicitly
denied that the reproduced sound was affected by the ultra-tweeter, and
also denied, when presented with the ultrasonics alone, that any sound
at all was being played."
|
One wonders if this, um, ground breaking work will *ever* be confirmed.
--
-S
"The most appealing intuitive argument for atheism is the mindblowing stupidity of religious
fundamentalists." -- Ginger Yellow |
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Guest
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| Posted:
Wed Oct 26, 2005 4:42 am Post subject:
Re: FR speaker question |
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"He does cite a result reported by Oohashi - who recorded a gamelan (an
Indonesian percussive gong chime orchestra) "to a bandwidth of 60 kHz, and
played back the recording to listeners through a speaker system with an
extra tweeter for the range above 26 kHz ... The experimenters found that
the listeners' EEGs and their subjective ratings of the sound quality were
affected by whether this "ultra-tweeter" was on or off, even though the
listeners explicitly denied that the reproduced sound was affected by the
ultra-tweeter, and also denied, when presented with the ultrasonics alone,
that any sound at all was being played."
This needs redone to exclude bone conduction of sound. In which case it
would be not unlike those bottom thumpers people add to their chairs to
"feel" the bass. A set of ear plugs would do the job nicely to exclude
ear drum involvement. |
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Uptown Audio
Guest
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| Posted:
Sat Nov 05, 2005 5:42 am Post subject:
Re: FR speaker question |
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Analog audio is not limited by "brick wall" digital filters. It is
only limited to the capabilities of the recording and playback system.
One thing that no one has mentioned is the effect of cumulative
harmonics as they act in real life. When the harmonics of these
instruments combine they can form third and separate harmonics. For
example, (and I will adimit that these figures are just random and for
illustration only but actual examples can be provided by those in the
acoustical engineering fields) a fundamental note around 100hz may
have a hamonic at 60khz and another at around 30khz. These harmonics
can combine to create a third frequency at perhaps 2000hz, which would
be clearly audible, if at a reduced level in relation to the rest of
the fundamentals. These frequencies would be absent without the
systems ability to produce the higher frequencies. That sounds pretty
amazing and it is to me, but was explained to me by an acoustics
engineer.
Another reason that supertweeters can be effective is in limiting the
range of the tweeter to keep within better operating parameters. For
example, rather than requiring a tweeter to perform thoughout its
range and into a resonance or peak, it can be crossed-over to the
supertweeter. Tannoy has done this with some of their speakers at
14khz. It has an effect on the transient response of frequencies that
we would define as bass frequencies so it is definately interesting
and worth a listen.
Other companies have begun to produce tweeters with extended operating
ranges as well. So it is not always required to have a separate
tweeter and a cross-over to get some good extended bandwidth. Focal -
JM Lab has designed some tweeters that have not only extended upper
range capability, but also are able to play lower frequencies without
distortion. That allows them to move the x-over points lower in the
spectrum and out of the critical 2500-3khz range where so many other
companies typically place thier filters. That helps with not only
lowering harmonic distortion but also with keeping phase shift out of
that region where we are most sensitive.
-Bill
www.uptownaudio.com
Roanoke VA
(540) 343-1250
<rotor451@optusnet.com.au> wrote in message
news:djishe0c7g@news3.newsguy.com...
| Quote: | The frequency response of Super audio CD (SACD), the new format
developed by Sony and Philips extends out to around 100 KHz - so
there
is a source available that can exercise this extended high frequency
performance.
Many instruments produce harmonics well beyond 20KHz. For example a
Trumpet with Harmon mute produces harmonics as high as 80Khz; a
French
horn, 90KHz. 40% of the power in a cymbal crash is represented by
frequencies above 20KHz. These figures are taken from a paper titled
"There's Life Above 20 Kilohertz! - A Survey of Musical Instrument
Spectra to 102.4 KHz" by James Boyk available at
http://www.cco.caltech.edu/~boyk/spectra/spectra.htm
Boyk does not express an opinion on whether this high frequency
energy
is perceptible. He does cite a result reported by Oohashi - who
recorded a gamelan (an Indonesian percussive gong chime orchestra)
"to
a bandwidth of 60 kHz, and played back the recording to listeners
through a speaker system with an extra tweeter for the range above
26
kHz ... The experimenters found that the listeners' EEGs and their
subjective ratings of the sound quality were affected by whether
this
"ultra-tweeter" was on or off, even though the listeners explicitly
denied that the reproduced sound was affected by the ultra-tweeter,
and
also denied, when presented with the ultrasonics alone, that any
sound
at all was being played."
Who knows?
rotor451 |
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Kalman Rubinson
Guest
|
| Posted:
Sat Nov 05, 2005 5:42 am Post subject:
Re: FR speaker question |
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On 5 Nov 2005 01:16:04 GMT, Uptown Audio <uptownaudio@rev.net> wrote:
| Quote: | Analog audio is not limited by "brick wall" digital filters. It is
only limited to the capabilities of the recording and playback system.
One thing that no one has mentioned is the effect of cumulative
harmonics as they act in real life. When the harmonics of these
instruments combine they can form third and separate harmonics. For
example, (and I will adimit that these figures are just random and for
illustration only but actual examples can be provided by those in the
acoustical engineering fields) a fundamental note around 100hz may
have a hamonic at 60khz and another at around 30khz. These harmonics
can combine to create a third frequency at perhaps 2000hz, which would
be clearly audible, if at a reduced level in relation to the rest of
the fundamentals. These frequencies would be absent without the
systems ability to produce the higher frequencies. That sounds pretty
amazing and it is to me, but was explained to me by an acoustics
engineer.
|
It is an interesting point. However, unless the instrument is
electronic, the subharmonics and intermodulation tones will be created
at the performance, acoustically, and then recorded. Therefore, the
supersonic tones needed to produce them have already done the job and
are no longer required.
Kal |
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Steven Sullivan
Guest
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| Posted:
Mon Nov 07, 2005 12:46 am Post subject:
Re: FR speaker question |
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Uptown Audio <uptownaudio@rev.net> wrote:
| Quote: | Analog audio is not limited by "brick wall" digital filters. It is
only limited to the capabilities of the recording and playback system.
One thing that no one has mentioned is the effect of cumulative
harmonics as they act in real life. When the harmonics of these
instruments combine they can form third and separate harmonics. For
example, (and I will adimit that these figures are just random and for
illustration only but actual examples can be provided by those in the
acoustical engineering fields) a fundamental note around 100hz may
have a hamonic at 60khz and another at around 30khz. These harmonics
can combine to create a third frequency at perhaps 2000hz, which would
be clearly audible, if at a reduced level in relation to the rest of
the fundamentals. These frequencies would be absent without the
systems ability to produce the higher frequencies. That sounds pretty
amazing and it is to me, but was explained to me by an acoustics
engineer.
|
The effect has been known about for ages. The important point it
illustrates re_ home audio,
however, is that all you *hear* are the effects occuring *within* the
audible passband. Those are captured by any competent recording.
It's not necessary to play back the supra-audible content as well.
--
-S
"The most appealing intuitive argument for atheism is the mindblowing stupidity of religious
fundamentalists." -- Ginger Yellow |
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stealthaxe
Guest
|
| Posted:
Wed Nov 09, 2005 5:42 am Post subject:
Re: FR speaker question |
|
|
Uptown Audio <uptownaudio@rev.net> wrote in
news:dkh14k0daj@news1.newsguy.com:
| Quote: | Analog audio is not limited by "brick wall" digital filters. It is
only limited to the capabilities of the recording and playback system.
One thing that no one has mentioned is the effect of cumulative
harmonics as they act in real life. When the harmonics of these
instruments combine they can form third and separate harmonics. For
example, (and I will adimit that these figures are just random and for
illustration only but actual examples can be provided by those in the
acoustical engineering fields) a fundamental note around 100hz may
have a hamonic at 60khz and another at around 30khz. These harmonics
can combine to create a third frequency at perhaps 2000hz, which would
be clearly audible, if at a reduced level in relation to the rest of
the fundamentals. These frequencies would be absent without the
systems ability to produce the higher frequencies. That sounds pretty
amazing and it is to me, but was explained to me by an acoustics
engineer.
|
there's a lot of non-science in all of this reasoning.
first, what's the mechanism by which a 60 kHz and a 30 kHz signal would
combine to produce a 2 kHz signal??
second, if such combining did happen, a microphone would likely grab the
2 kHz signal without the higher ones being necessary. in fact, IM
distortion would probably make the 2 kHz tone even more prevalent if it
indeed exists in the 1st place.
There's not many recordings analog or otherwise that are going to give
you the 60 kHz component. engineers and recording equipment filter that
stuff out on purpose.
in short, this sounds to me like a lot of hooey.
you see a lot of strange claims in the high end audio salons. having
spent quite a bit of time in recording studios, i can say that many of
these high-enders are spending a lot of money to retrieve something that
just isn't there. i see fanaticisms that don't really make sense.
let's take the no-negative-feedback simple-circuit purists. ok, have
these guys ever seen a recording console? full of op amps and
capacitors? if they actually had any idea how many $ 3 chips a recording
went through before it got to them, there'd be more people on the digital
bandwagon.
old recordings are a different story, but only if you get a vinyl disc
pressed at least 30 years ago.
sure the idea is to not do any further damage to the signal, but man.
the extremists amuse me no end.
| Quote: | Another reason that supertweeters can be effective is in limiting the
range of the tweeter to keep within better operating parameters. For
example, rather than requiring a tweeter to perform thoughout its
range and into a resonance or peak, it can be crossed-over to the
supertweeter. Tannoy has done this with some of their speakers at
14khz. It has an effect on the transient response of frequencies that
we would define as bass frequencies so it is definately interesting
and worth a listen.
|
this sounds far more plausible. for me, i like my ribbons.
--
stealthaxe |
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