this thread split off from here http://www.diyaudio.com/forums/full-range/137075-audience-a3-11.html#post2075855 
I need some 'expert' help regarding idea of using RAAL ribbons (with Audience A3s as midrange array, or maybe cheaper Fountek 3" as midranges). Of course this assumed one would even want to try adding a tweeter to full-range drivers that already offer good trebles.
Maybe I should post this elsewhere on this site -- where?
IF it's possible, how can a high-order (e.g. 4th order) passive speaker crossover be designed that maintains flat amplitude response AND, at the same time, maintain linear-phase coherency through the crossover region, assuming reasonably wide-bandwidth drivers are employed that have extended response above & below the 4th order crossover frequency ---
I was astounded to read YG Acoustics' advertisement in the current issue of TAS. Also, there's a review of the Kipod Studio Loudspeaker (TAS 199). YG Acoustics designer claimed that he developed new software that simultaneously optimizes 4th-order crossover's amplitude and phase such that deviation from perfect phase linearity is only 5 degrees
-- and that the total phase rotation for the 4th order crossover slopes from 200 Hz on up is only 360 degrees! Heretofore, impression was that such linear phase reponse was essentially "impossible" to achieve with conventional higher-order passive crossovers (like L-R 4th order). Theoretically can get coherent phase shift with first-order crossover approach, but I don't see how YG Acoustics can get 4th order rolloff crossover with a single 360 degree phase rotation for the speaker response from 200 Hz up. 
Doesn't seem to obey electrical network theory.
Puzzle: Maybe somebody can explain how YG Acoustics combines 4th order crossover slopes while at the same time gets only first-order phase rotation?
Guess that's why they say that their YG speakers are the 'best in the world'?
I need some 'expert' help regarding idea of using RAAL ribbons (with Audience A3s as midrange array, or maybe cheaper Fountek 3" as midranges). Of course this assumed one would even want to try adding a tweeter to full-range drivers that already offer good trebles.
Maybe I should post this elsewhere on this site -- where?
IF it's possible, how can a high-order (e.g. 4th order) passive speaker crossover be designed that maintains flat amplitude response AND, at the same time, maintain linear-phase coherency through the crossover region, assuming reasonably wide-bandwidth drivers are employed that have extended response above & below the 4th order crossover frequency ---
I was astounded to read YG Acoustics' advertisement in the current issue of TAS. Also, there's a review of the Kipod Studio Loudspeaker (TAS 199). YG Acoustics designer claimed that he developed new software that simultaneously optimizes 4th-order crossover's amplitude and phase such that deviation from perfect phase linearity is only 5 degrees
-- and that the total phase rotation for the 4th order crossover slopes from 200 Hz on up is only 360 degrees! Heretofore, impression was that such linear phase reponse was essentially "impossible" to achieve with conventional higher-order passive crossovers (like L-R 4th order). Theoretically can get coherent phase shift with first-order crossover approach, but I don't see how YG Acoustics can get 4th order rolloff crossover with a single 360 degree phase rotation for the speaker response from 200 Hz up. Doesn't seem to obey electrical network theory.
Puzzle: Maybe somebody can explain how YG Acoustics combines 4th order crossover slopes while at the same time gets only first-order phase rotation?
Guess that's why they say that their YG speakers are the 'best in the world'?
I was astounded to read YG Acoustics' advertisement in the current issue of TAS. Also, there's a review of the Kipod Studio Loudspeaker (TAS 199). YG Acoustics designer claimed that he developed new software that simultaneously optimizes 4th-order crossover's amplitude and phase such that deviation from perfect phase linearity is only 5 degrees
Doesn't seem to obey electrical network theory.
Puzzle: Maybe somebody can explain how YG Acoustics combines 4th order crossover slopes while at the same time gets only first-order phase rotation?
Guess that's why they say that their YG speakers are the 'best in the world'?
If it's in an advert, it must be true
the best in the world?
really?
never heard that before
what about the inevitable upgrades?
all cynicism aside, they might well sound very nice indeed, but am I the only one long since bored with this type of hyperbole?
Doesn't a 4th order LR have only 360 degrees of phase rotation?
There are ways to maintain continuous phase response using high-order active analog filters (LR AES paper use of all-pass filters), but reports are that the cure is worse than the disease.
With small FRs with very good HF response, and a tweeter with good LF response, one should have the overlap needed (if not the ability to get the drivers close enuff together) to use a 1st order XO.
dave
There are ways to maintain continuous phase response using high-order active analog filters (LR AES paper use of all-pass filters), but reports are that the cure is worse than the disease.
With small FRs with very good HF response, and a tweeter with good LF response, one should have the overlap needed (if not the ability to get the drivers close enuff together) to use a 1st order XO.
dave
Dave,
I believe you are correct about 4th order LR having 360 degrees rotation through crossover region (typ. 90 degrees shift per network pole). However, as I recall, YG Acoustics appears to be unique in maintaining only 5 degree error from linear phase characteristic for their symmetrical-slope passive crossover network = constant group delay in a fourth-order LR-like crossover, even when including all the crossover network frequency response (driver) compensation adjustments (this is from my poor memory of the applicable crossover theory - which admittedly is rusty -- the reason why I would appreciate other viewpoints). Phase rotation over the entire 200 Hz on up speaker bandwidth seems to be more comparible to first-order speaker designs (e.g. Thiel) -- again please see the TAS YG Acoustics advertisement.
Vance Dickason's "Loudspeaker Design Cookbook" does present formulas for a so-called "forth-order linear-phase" passive crossover. He says that the asymetrical derivation makes this particular filter's suitability questionable.
This crossover's name sounds very intriguing, but still, the summed group delay for this forth-order linear-phase" crossover is not equal or better than a first-order crossover (I understand).
In the TAS advertisement the YG Acoustics claim of only 5 degree phase nonlinearity and perfomance superior to a first-order crossover is remarkable but very hard to believe (for me, anyway).
-- wish I could duplicate the YG Acoustics 24 db/oct with constant group delay approach for a RAAL ribbon tweeter!
Such a small phase linearity error means that all frequency components are 'coherently' radiated all at the same time (constant group delay). Why can't the other high-end speaker companies achieve these coherent 4th order slopes too?
reference: Thiel Inc. first-order crossover systems are designed to provide phase coherent transitions between very wide bandwidth drivers. Thiel seems to feel that only first order passive crossovers can do the job.
I believe you are correct about 4th order LR having 360 degrees rotation through crossover region (typ. 90 degrees shift per network pole). However, as I recall, YG Acoustics appears to be unique in maintaining only 5 degree error from linear phase characteristic for their symmetrical-slope passive crossover network = constant group delay in a fourth-order LR-like crossover, even when including all the crossover network frequency response (driver) compensation adjustments (this is from my poor memory of the applicable crossover theory - which admittedly is rusty -- the reason why I would appreciate other viewpoints). Phase rotation over the entire 200 Hz on up speaker bandwidth seems to be more comparible to first-order speaker designs (e.g. Thiel) -- again please see the TAS YG Acoustics advertisement.
Vance Dickason's "Loudspeaker Design Cookbook" does present formulas for a so-called "forth-order linear-phase" passive crossover. He says that the asymetrical derivation makes this particular filter's suitability questionable.
This crossover's name sounds very intriguing, but still, the summed group delay for this forth-order linear-phase" crossover is not equal or better than a first-order crossover (I understand).
In the TAS advertisement the YG Acoustics claim of only 5 degree phase nonlinearity and perfomance superior to a first-order crossover is remarkable but very hard to believe (for me, anyway).
-- wish I could duplicate the YG Acoustics 24 db/oct with constant group delay approach for a RAAL ribbon tweeter!
Such a small phase linearity error means that all frequency components are 'coherently' radiated all at the same time (constant group delay). Why can't the other high-end speaker companies achieve these coherent 4th order slopes too?
reference: Thiel Inc. first-order crossover systems are designed to provide phase coherent transitions between very wide bandwidth drivers. Thiel seems to feel that only first order passive crossovers can do the job.
Me too. Keep in mind that there are a number of phase related terms that have different meaning.
I have read everything i can about linear phase XOs, and it seems to me that you are still stuck with 1st order active or passive or subtractive active (which have their own set of issues).
My solution to the problem is to have either no XO or one below 400 Hz.
dave
Dave,
Thanks for your reply.
Sorry, I didn't understand what you said in your post: " -- or passive of subtractive active (which have their own set of issues)" -- could you clarify this -- it would help me to understand more about linear phase XOs.
Anyway, I gather that you don't believe claim that YG Acoustics can achieve constant group delay, while at the same time, achieving symmetrical 24 dB/oct crossover slopes ?
If they really can do this, it would be a wonderful idea for us DIY speaker hobbyists to emulate.
Thanks for your reply.
Sorry, I didn't understand what you said in your post: " -- or passive of subtractive active (which have their own set of issues)" -- could you clarify this -- it would help me to understand more about linear phase XOs.
Anyway, I gather that you don't believe claim that YG Acoustics can achieve constant group delay, while at the same time, achieving symmetrical 24 dB/oct crossover slopes ?
If they really can do this, it would be a wonderful idea for us DIY speaker hobbyists to emulate.
Here is the Stereophile add. It isn't a minimum phase design.
http://www.ygacoustics.com/YG_Acoustics_ad_for_Stereophile_May_2008.pdf
They talk about the lowest "relative" phase.
Stereophile: YG Acoustics Anat Reference II Professional loudspeaker
Looking at the step response shows what's going on.
as for "the best loudspeaker on Earth"..
Looking at the Burmeister B99's linearity seems to suggest otherwise:
http://stereophile.com/floorloudspeakers/601/index6.html
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Thanks very much for your insightful observation regarding the Stereophile review's measurements: "Fig.8 YGA Anat Reference II Main Module, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth)".
This initial rise of the step response waveform 'could have/should have' been improved by time-aligning the acoustic-centers of the drivers?
Too bad, since the use of a YG Acoustic speaker's tweeter-waveguide may have been used much more advantagely to offset the tweeter behind the woofer - so I think, so far, at first impression ...
Thanks again,
Bill
This initial rise of the step response waveform 'could have/should have' been improved by time-aligning the acoustic-centers of the drivers?
Too bad, since the use of a YG Acoustic speaker's tweeter-waveguide may have been used much more advantagely to offset the tweeter behind the woofer - so I think, so far, at first impression ...
Thanks again,
Bill
Do keep in mind that the acoustic centre of a driver changes as soon as the driver starts moving so aligning acoustic centres can only ever be approximate.
dave
with a 4th order x-over, about 1 octave on either side of the crossover point is off. Say at a 1khz crossover, the phase shoots toward positive infinity after about 500hz. Then just after the 1khz, the tweeter phase comes up from negative infinity towards zero.
An 18db crossover at 80hz causes the sub about 20ms delay then more as it gets closer to the crossover point.
Thats why a deep 2 way seems quicker, it has better phase.
And a passive or active crossover, the components or opamps shift the phase. So if you have a 6db filter on 2 full range drivers, 1 driver will be closer to you than the other for alignment (passing closest to a square wave) because the inductor shoves the driver back and the cap moves it forward (or vise verse, I forget).
And a driver may be rolling off, turning an 18db crossover to a 24db acoustic.
Crossovers are messy, and the driver's changing impedence doesn't make it any easier.
You pay for a well designed crossover, not just the price of the drivers.
Norman
An 18db crossover at 80hz causes the sub about 20ms delay then more as it gets closer to the crossover point.
Thats why a deep 2 way seems quicker, it has better phase.
And a passive or active crossover, the components or opamps shift the phase. So if you have a 6db filter on 2 full range drivers, 1 driver will be closer to you than the other for alignment (passing closest to a square wave) because the inductor shoves the driver back and the cap moves it forward (or vise verse, I forget).
And a driver may be rolling off, turning an 18db crossover to a 24db acoustic.
Crossovers are messy, and the driver's changing impedence doesn't make it any easier.
You pay for a well designed crossover, not just the price of the drivers.
Norman
from Roy Hall (Green Mountain Audio)
"If a speaker uses a 4th-order crossover at 3,000Hz (common for a 1" tweeter), what will we actually hear from this system?
*
Down at 1,500Hz, the tweeter isn't really contributing. Thus, the image is formed by the woofer. However, the woofer moves back by one inch because the circuit imposes 75 degrees of shift at 1,500Hz. But the dimensional shift is always relative to that 3,000Hz wavelength reference point, where (75 degrees/360) x (13,500ips/3000Hz) = 1 inch.
*
At 2,000Hz, the tweeter output is now audible (12dB softer then the woofer). We hear the image from the woofer move back by a little more, to 1.1" (90-degrees of 3,000Hz equals ¼ wavelength). Yet the tweeter is actually forward by 3/4ths of a wavelength of 3,000Hz, or 3.4". As a soprano's harmonics move through this region, we'll hear the image begin to split by 4.5" total. The image will begin to diffuse from front-to-rear, and harmonics structures will begin to fuzz over -- the sound will become grainy.
*
At 3,000Hz, the woofer and tweeter contribute equally. However, the woofer image has moved backwards by 2.25", for the same total split of 4.5". At this point, the image is very confusing and textures are at maximum graininess. The voice is split into two parts -- 'esses' and 'tees' from the tweeter arrive first, stretched out from the sound of the throat as delivered by the woofer -- an unnatural occurrence. The voice hisses and spits, and strings are edgy*. There'll be comments such as "the transients are etched..." "...detail thrust at the listener..." "...this speaker seems very fast..." "...analytical..." and "...very sensitive to electronics...." Of course, these comments would be expected because the tweeter arrived first!
* Not all higher-order designs sound like this, because there are ways to disguise the problem. Again, if the designer tunes the "Q" of the circuit (computer-optimized, or by ear), or otherwise misaligns the actual crossover point, the graininess will be reduced, along with transient response. The spatial distortion remains, however, and even a solo flute can be heard to wander.
*
At 5,100Hz, the woofer is now 12dB softer than the tweeter -- just audible. It's now 3.4" behind the tweeter's highest frequencies, and the tweeter is still 1.1" ahead -- a 4.5" total split.
*
At 12,000Hz, two octaves above the crossover point, the woofer output is non-existent, but the tweeter output will still arrive 30 degrees ahead (0.4 inches) of its very top end at 24,000Hz, where phase error returns to zero. This will disturb the timing of a wooden stick striking a bell, blurring its image. A musician striking the bell .4" late is definitely behind the beat as well."
Green Mountain Audio - Speaker-Time-Phase-Coherence - Loudspeaker Phase Accuracy and MusicalTiming
"Higher-order circuits, from 2nd on up, cannot be made time-coherent, because that Phase Difference each one exhibits at the crossover point does not remain a Constant Phase Difference when the tones move away from the crossover point. In other words, the drivers' Relative Phase Difference is always changing."
AudiogoN Forums: Phase Coherence or Time Alignment: Which More Imp?
Here on page 2 and 8 show the phase of a 24db crossover from eaw.
http://www.aalt.com.au/FAQ/DSP_setting_fundamentals_or_What_is_the_crossover_point.pdf
here is a picture
Norman
"If a speaker uses a 4th-order crossover at 3,000Hz (common for a 1" tweeter), what will we actually hear from this system?
*
Down at 1,500Hz, the tweeter isn't really contributing. Thus, the image is formed by the woofer. However, the woofer moves back by one inch because the circuit imposes 75 degrees of shift at 1,500Hz. But the dimensional shift is always relative to that 3,000Hz wavelength reference point, where (75 degrees/360) x (13,500ips/3000Hz) = 1 inch.
*
At 2,000Hz, the tweeter output is now audible (12dB softer then the woofer). We hear the image from the woofer move back by a little more, to 1.1" (90-degrees of 3,000Hz equals ¼ wavelength). Yet the tweeter is actually forward by 3/4ths of a wavelength of 3,000Hz, or 3.4". As a soprano's harmonics move through this region, we'll hear the image begin to split by 4.5" total. The image will begin to diffuse from front-to-rear, and harmonics structures will begin to fuzz over -- the sound will become grainy.
*
At 3,000Hz, the woofer and tweeter contribute equally. However, the woofer image has moved backwards by 2.25", for the same total split of 4.5". At this point, the image is very confusing and textures are at maximum graininess. The voice is split into two parts -- 'esses' and 'tees' from the tweeter arrive first, stretched out from the sound of the throat as delivered by the woofer -- an unnatural occurrence. The voice hisses and spits, and strings are edgy*. There'll be comments such as "the transients are etched..." "...detail thrust at the listener..." "...this speaker seems very fast..." "...analytical..." and "...very sensitive to electronics...." Of course, these comments would be expected because the tweeter arrived first!
* Not all higher-order designs sound like this, because there are ways to disguise the problem. Again, if the designer tunes the "Q" of the circuit (computer-optimized, or by ear), or otherwise misaligns the actual crossover point, the graininess will be reduced, along with transient response. The spatial distortion remains, however, and even a solo flute can be heard to wander.
*
At 5,100Hz, the woofer is now 12dB softer than the tweeter -- just audible. It's now 3.4" behind the tweeter's highest frequencies, and the tweeter is still 1.1" ahead -- a 4.5" total split.
*
At 12,000Hz, two octaves above the crossover point, the woofer output is non-existent, but the tweeter output will still arrive 30 degrees ahead (0.4 inches) of its very top end at 24,000Hz, where phase error returns to zero. This will disturb the timing of a wooden stick striking a bell, blurring its image. A musician striking the bell .4" late is definitely behind the beat as well."
Green Mountain Audio - Speaker-Time-Phase-Coherence - Loudspeaker Phase Accuracy and MusicalTiming
"Higher-order circuits, from 2nd on up, cannot be made time-coherent, because that Phase Difference each one exhibits at the crossover point does not remain a Constant Phase Difference when the tones move away from the crossover point. In other words, the drivers' Relative Phase Difference is always changing."
AudiogoN Forums: Phase Coherence or Time Alignment: Which More Imp?
Here on page 2 and 8 show the phase of a 24db crossover from eaw.
http://www.aalt.com.au/FAQ/DSP_setting_fundamentals_or_What_is_the_crossover_point.pdf
here is a picture
Norman
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Here is something "timely" with regard to this discussion:
Siri's Killer Note
Note that you can have a 1st order high pass with a 4th order *bessel* low pass and maintain a minimum phase design. It's the technique that Spica used.
Stereophile: Spica TC-60 loudspeaker
You can also use Duelunds approach in a 1st order filter and maintain minimum phase with a net "higher order" filter:
http://www.htguide.com/forum/showthread.php4?t=34839
..btw, this should probably all be "split-off" into it's own thread and placed in the Multi-way forum.
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planet10, yup you are right, it shoots off to -180 and pos 180 degrees.
And of coarse the physical delay, a 24db moves an acoustic center back and the other forward, but you can slide the drivers back and forth till the match up.
Yes, the fast way (fullrange augmented sub technology, is that right ?) should be the new wave.
My old thiels ran 6db time aligned, but the midrange was clearer on my dual 4", but the thiels had some sparkly highs and more bass. But the cabinet (stuffed big time) had some resonances that added well to male voices. I've given them to my kid to get him hooked into stereo equipment like me. All good drug dealers give the first sample of crack for free. It's nice when he say "yea, I'm hearing all sorts of stuff in games and music I hadn't b4."
To me the crossover, even a 6db, adds some haze to the drivers. And the 2 different materials can act quite differently. But I'm time aligned.
Norman
And of coarse the physical delay, a 24db moves an acoustic center back and the other forward, but you can slide the drivers back and forth till the match up.
Yes, the fast way (fullrange augmented sub technology, is that right ?) should be the new wave.
My old thiels ran 6db time aligned, but the midrange was clearer on my dual 4", but the thiels had some sparkly highs and more bass. But the cabinet (stuffed big time) had some resonances that added well to male voices. I've given them to my kid to get him hooked into stereo equipment like me. All good drug dealers give the first sample of crack for free. It's nice when he say "yea, I'm hearing all sorts of stuff in games and music I hadn't b4."
To me the crossover, even a 6db, adds some haze to the drivers. And the 2 different materials can act quite differently. But I'm time aligned.
Norman
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Phase plots for 4th order filters
Norman,
You said about a 4th order crossover: "Say at a 1khz crossover, the phase shoots toward positive infinity after about 500hz. Then just after the 1khz, the tweeter phase comes up from negative infinity towards zero."
The way phase shift graphs are plotted for crossover networks, and by speaker measurement software like SoundEasy, can be misleading - phase plot is actually continuous as the plotted phase wraps depending on the particular phase plot's scale. The reference you cite with the phase plot picture says:
"Attention needs to be given to the “wrapping” of the phase plot. The y-axis of this plot ranges from –270 degrees to +90 degrees. Phase plots usually only represent 360 degrees of phase; since 0 degrees and 360 degrees are equal, as are 90 and –270, 180 and –180, etc. It may not be intuitive that the phase responses shown consistently decrease."
In the "LoudSpeaker Design Cookbook" by Vance Dickson, for typical 4th-order crossovers, the high & low section summed resposes are plotted (summed crossover phase, magnitude, and group-delay). The phase plots resemble the picture you posted. For example the 4th-order Linkwitz-Riley is an all-pass network which sums to a flat magnitude, and the group delay is a smooth curve with a only slight peak just below the nominal 1 kHz crossover frequency. Dickson's 4th-order "Linear-phase" crossover filter has a summed group delay which is nearly flat.
From Wikipedia: "Group delay is a measure of the transit time of a signal through a device under test (DUT), versus frequency. Group delay is a useful measure of phase distortion, and is calculated by differentiating the insertion phase response of the DUT versus frequency. Another way to say this is that group delay is a measure of the slope of the transmission phase response."
So if a 4th order crossover filter's group delay is a continous, fairly smooth function, then the phase shift doesn't have discontinuities.
The 4th order LR filter (1 kHz nominal crossover frequency) has roughly 0.5 millisecond group delay error when plotted from 20 Hz to 20 kHz (Dickson's plot). This implies that phase is continous, although not linear Vs. frequency.
A controversial question is: How audible is a time offset of 0.5 millisecond?
Bill
Norman,
You said about a 4th order crossover: "Say at a 1khz crossover, the phase shoots toward positive infinity after about 500hz. Then just after the 1khz, the tweeter phase comes up from negative infinity towards zero."
The way phase shift graphs are plotted for crossover networks, and by speaker measurement software like SoundEasy, can be misleading - phase plot is actually continuous as the plotted phase wraps depending on the particular phase plot's scale. The reference you cite with the phase plot picture says:
"Attention needs to be given to the “wrapping” of the phase plot. The y-axis of this plot ranges from –270 degrees to +90 degrees. Phase plots usually only represent 360 degrees of phase; since 0 degrees and 360 degrees are equal, as are 90 and –270, 180 and –180, etc. It may not be intuitive that the phase responses shown consistently decrease."
In the "LoudSpeaker Design Cookbook" by Vance Dickson, for typical 4th-order crossovers, the high & low section summed resposes are plotted (summed crossover phase, magnitude, and group-delay). The phase plots resemble the picture you posted. For example the 4th-order Linkwitz-Riley is an all-pass network which sums to a flat magnitude, and the group delay is a smooth curve with a only slight peak just below the nominal 1 kHz crossover frequency. Dickson's 4th-order "Linear-phase" crossover filter has a summed group delay which is nearly flat.
From Wikipedia: "Group delay is a measure of the transit time of a signal through a device under test (DUT), versus frequency. Group delay is a useful measure of phase distortion, and is calculated by differentiating the insertion phase response of the DUT versus frequency. Another way to say this is that group delay is a measure of the slope of the transmission phase response."
So if a 4th order crossover filter's group delay is a continous, fairly smooth function, then the phase shift doesn't have discontinuities.
The 4th order LR filter (1 kHz nominal crossover frequency) has roughly 0.5 millisecond group delay error when plotted from 20 Hz to 20 kHz (Dickson's plot). This implies that phase is continous, although not linear Vs. frequency.
A controversial question is: How audible is a time offset of 0.5 millisecond?
Bill
Scott,
The PDF of the 2008 YG Acoustics advertisement appears somewhat similar to the 2010 YG Acoustics ad in TAS, but the current 2010 ad version is more extensive with more plots and even more spectacular performance claims -- my impression.
The current TAS ad seems to put more emphasis on claimed phase-linearity & coherent superiority to even a competitor's very-well-designed first-order crossover speaker (e.g Thiel ?).
As I recall, YG Acoustics cliams that their optimized 4th-order crossover beats the example 1st-order design in linear-phase error (+-5 degrees) over a wider speaker banwidth of 200 Hz to 20 kHz.
I got the impression that YG Acoustics 'KIPOD' speaker seems to offer improvement in the 2010 advertisement measured response plots - I understand that some (recent) changes may have been made to the wide-band woofer and tweeter, and perhaps the matched crossover as well - again, from memory.
Anyway, it might be worthwhile to look at TAS current issue.
Bill
The PDF of the 2008 YG Acoustics advertisement appears somewhat similar to the 2010 YG Acoustics ad in TAS, but the current 2010 ad version is more extensive with more plots and even more spectacular performance claims -- my impression.
The current TAS ad seems to put more emphasis on claimed phase-linearity & coherent superiority to even a competitor's very-well-designed first-order crossover speaker (e.g Thiel ?).
As I recall, YG Acoustics cliams that their optimized 4th-order crossover beats the example 1st-order design in linear-phase error (+-5 degrees) over a wider speaker banwidth of 200 Hz to 20 kHz.
I got the impression that YG Acoustics 'KIPOD' speaker seems to offer improvement in the 2010 advertisement measured response plots - I understand that some (recent) changes may have been made to the wide-band woofer and tweeter, and perhaps the matched crossover as well - again, from memory.
Anyway, it might be worthwhile to look at TAS current issue.
Bill
Interesting topic. One thing that comes to mind about any speakers mentioned, is that at some point of course, they must also be connected to an amplifier.
From Stereophile: (note highlighted reference)
"The Anat Reference II's voltage sensitivity was significantly higher than average, at an estimated 90.1dB(B)/2.83V/m, though it is a little lower than the specified 92dB. The impedance is specified as 4 ohms, with a 2.7 ohm minimum. However, while our sample was basically a 4 ohm design, the magnitude did drop to almost 2 ohms in the mid-treble—which is why WP felt the tubed VTL amplifiers lacked sparkle—and below 2 ohms above 25kHz (fig.1). The phase angle also varies widely, and the combinations of 4 ohms magnitude and –53° capacitive angle at 110Hz, and 4.8 ohms and –46° at 2.4kHz, mandate the use of a power amplifier that can deliver unrestricted amounts of current. As the Main Module is not fed from a crossover when used with the woofer modules, the former magnitude/phase combination will be unaffected."
This makes me think that at some point, adding complexity to simplicity may not yield all the results being searched for. It wouldn't seem sensible to take a full range driver, designed to stand alone (or almost), in a low power application, tubed or otherwise, and make things even more difficult on the amp which affects performance negatively.
Also, since you are not re-engineering the drivers themselves to fit a criteria, then you could be trying to fit 10lbs of sand in a 1lb bag, or so to speak.
From Stereophile: (note highlighted reference)
"The Anat Reference II's voltage sensitivity was significantly higher than average, at an estimated 90.1dB(B)/2.83V/m, though it is a little lower than the specified 92dB. The impedance is specified as 4 ohms, with a 2.7 ohm minimum. However, while our sample was basically a 4 ohm design, the magnitude did drop to almost 2 ohms in the mid-treble—which is why WP felt the tubed VTL amplifiers lacked sparkle—and below 2 ohms above 25kHz (fig.1). The phase angle also varies widely, and the combinations of 4 ohms magnitude and –53° capacitive angle at 110Hz, and 4.8 ohms and –46° at 2.4kHz, mandate the use of a power amplifier that can deliver unrestricted amounts of current. As the Main Module is not fed from a crossover when used with the woofer modules, the former magnitude/phase combination will be unaffected."
This makes me think that at some point, adding complexity to simplicity may not yield all the results being searched for. It wouldn't seem sensible to take a full range driver, designed to stand alone (or almost), in a low power application, tubed or otherwise, and make things even more difficult on the amp which affects performance negatively.
Also, since you are not re-engineering the drivers themselves to fit a criteria, then you could be trying to fit 10lbs of sand in a 1lb bag, or so to speak.
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