I think the title is explicit enough 😉
I'd like to know the advantages and disadvantages of all these configurations. I still haven't found an explanation that satisfied me yet.
And if someone could explain me lobing, tilts, polar response and such things, I'll know everything I want for a momment 😀
Thanks
Alex
I'd like to know the advantages and disadvantages of all these configurations. I still haven't found an explanation that satisfied me yet.
And if someone could explain me lobing, tilts, polar response and such things, I'll know everything I want for a momment 😀
Thanks
Alex
Last edited by a moderator:
Answer - Coax!
Konnichiwa,
Very explicit. X-Rated I'd think.
Listen in order of personal preference and assuming identical M & T in all cases (except fullrange of course) and a crossover frequency that falls into a range where the "M" driver centerss are farther from the T driver Center than around 1/8 Wavelength of the crossover point....
Of course, in the end can make speakers that certain find to sound subjectively "good" in their personal settings using any of these arrangements and a few past that (line sources anyone?).
Fullrange
=========
Advantages - Point Source, Symmetrical Polar response without or with only minimal lobing, invariably fairly even off axis response.
Disadvantages - Non really
(except not easy to make a good one covering a wide bandwidth, possibly limited maximum SPL due to doppler modulation at very high SPL level with loads of bass, but again can be addressed by design and hence invariably expensive)
Coax
====
Advantages - Point Source, Symmetrical Polar response without or with only minimal lobing, invariably even off axis response.
Disadvantages - timealignment needs to be done by driver manufacturer or in the (active, digital or passive) X-Over
Semi-Coax
========
Advantages - Near Point Source, reasonably symmetrical polar response without or with only minimal lobing, fairly even off axis response.
Disadvantages - timealignment needs to be done in the (active, digital or passive) X-Over
TM - MT
========
Advantages - Non whatsoever apart from the possibility for mechanical timealignment, however the lobing structure is still comparably simple, compared to other options
Disadvantages - Asymetric Polar pattern (often strongly so) and problems integrating drivers.
Choices/Implications - with MT arrangement the first main lobe is reflected by the floor, which MAY be sound absorbing, with TM (tweeter on top) the first main lobe is beamed to thge ceiling where it will have a much longer arrival time to the listening position, which may or may not improve subjective Image hight and/or spatiality.
MTM
======
Advantages - Non whatsoever, except, the very ragged and messy vertical polar pattern is symmetrical which is VERY dubious as "advantage".
Disadvantages - Extremely messy Polar pattern, strong first main lobes pointing both towards the floor and ceiling can really mess up imaging etc., lobes created by both the two M Driver and each of these with the T Driver.
TMM - MMT
========
Advantages - Non whatsoever
Disadvantages - Extremely messy and asymetric Polar pattern and severe problems integrating and timealigning drivers.
Choices/Implications - with MMT arrangement the first several main lobes are reflected by the floor, which MAY be sound absorbing, with TM (tweeter on top) the first several main lobes are beamed to the ceiling where they will have a much longer arrival time to the listening position, which may or may not improve subjective Image hight and/or spatiality.
Best application would be using the second (M) as Woofer to help at lower end of the spectrum, so (T)(MW)(W) would be my best guess here using a dedicated woofer probably of slightly larger diameter.
Sayonara
Konnichiwa,
Bricolo said:
Very explicit. X-Rated I'd think.
Bricolo said:
Listen in order of personal preference and assuming identical M & T in all cases (except fullrange of course) and a crossover frequency that falls into a range where the "M" driver centerss are farther from the T driver Center than around 1/8 Wavelength of the crossover point....
Of course, in the end can make speakers that certain find to sound subjectively "good" in their personal settings using any of these arrangements and a few past that (line sources anyone?).
Fullrange
=========
Advantages - Point Source, Symmetrical Polar response without or with only minimal lobing, invariably fairly even off axis response.
Disadvantages - Non really
(except not easy to make a good one covering a wide bandwidth, possibly limited maximum SPL due to doppler modulation at very high SPL level with loads of bass, but again can be addressed by design and hence invariably expensive)
Coax
====
Advantages - Point Source, Symmetrical Polar response without or with only minimal lobing, invariably even off axis response.
Disadvantages - timealignment needs to be done by driver manufacturer or in the (active, digital or passive) X-Over
Semi-Coax
========
Advantages - Near Point Source, reasonably symmetrical polar response without or with only minimal lobing, fairly even off axis response.
Disadvantages - timealignment needs to be done in the (active, digital or passive) X-Over
TM - MT
========
Advantages - Non whatsoever apart from the possibility for mechanical timealignment, however the lobing structure is still comparably simple, compared to other options
Disadvantages - Asymetric Polar pattern (often strongly so) and problems integrating drivers.
Choices/Implications - with MT arrangement the first main lobe is reflected by the floor, which MAY be sound absorbing, with TM (tweeter on top) the first main lobe is beamed to thge ceiling where it will have a much longer arrival time to the listening position, which may or may not improve subjective Image hight and/or spatiality.
MTM
======
Advantages - Non whatsoever, except, the very ragged and messy vertical polar pattern is symmetrical which is VERY dubious as "advantage".
Disadvantages - Extremely messy Polar pattern, strong first main lobes pointing both towards the floor and ceiling can really mess up imaging etc., lobes created by both the two M Driver and each of these with the T Driver.
TMM - MMT
========
Advantages - Non whatsoever
Disadvantages - Extremely messy and asymetric Polar pattern and severe problems integrating and timealigning drivers.
Choices/Implications - with MMT arrangement the first several main lobes are reflected by the floor, which MAY be sound absorbing, with TM (tweeter on top) the first several main lobes are beamed to the ceiling where they will have a much longer arrival time to the listening position, which may or may not improve subjective Image hight and/or spatiality.
Best application would be using the second (M) as Woofer to help at lower end of the spectrum, so (T)(MW)(W) would be my best guess here using a dedicated woofer probably of slightly larger diameter.
Sayonara
Whao!
Thanks a lot, Thorsten! I wasn't exopecting such a precise answear.
You seem to be a fullrange addict 😉
PS: where can I learn what exactly are polar response/pattern, lobing, etc
PPS: I remember having read in the loudspeaker design cookbook that the lobe "direction" is different for each crossover order. Is this true?
Thanks a lot, Thorsten! I wasn't exopecting such a precise answear.
You seem to be a fullrange addict 😉
PS: where can I learn what exactly are polar response/pattern, lobing, etc
PPS: I remember having read in the loudspeaker design cookbook that the lobe "direction" is different for each crossover order. Is this true?
For different types of cross-over... yes, it is.
But what lobes are is perfectly described in the cookbook, so I suggest you take a look in the cookbook again, because I think it is hard to describe better than Vance has done in his book (not that I’m not willing to help, don’t get me wrong please…).
But what lobes are is perfectly described in the cookbook, so I suggest you take a look in the cookbook again, because I think it is hard to describe better than Vance has done in his book (not that I’m not willing to help, don’t get me wrong please…).
Eul said:
I rode this book some months ago, and I must admit that after all the good things I heard about, I was disapointed. I didn't find much usefull information in it, I don't understant why this book is condisered as a bible by some people.
A (not so) possible explanation could be that the french translation is less complete that the original one. I'll try to find the english version
I remember having read 2 or 3 pages in the loudspeaker design cookbook, about lobes, theyr orientation as a function of the XO's order, the accoustic centers alignment, the speaker configuration (TM, MTM...), but it was very basic 🙁
Here's a good critique of D'Appolito's 3/2 MTM design that gives a good introduction into polar response issues: http://www.birotechnology.com/articles/VSTWLA.html
GM
GM
I don't think the English version will be more detailed. It is seen as a bible for beginners, is describes every effect in the detail needed to understand what is is and what the effects are. To really understand al these affects you have to look further. THIS site is very good, it describes every effect very detailed. At first the it looks there is not much information but when you dig an read the articles you will see the is a huge amount of information on the site. From cross-over design to dipole speakers¡K. Good luck ƒº
Thorsten, when you said that a MT has it's main lobe beaming to the floor, and on a TM it's beaming to the ceiling
I was thinking about a solution to align the accoustic centers of the T and M
->using a sloped bafle (oriented to the floor for a TM, oriented to the ceiling for a MT)
When I want to have a horizontal main lobe, the solution is also to use a sloped bafle, but:
-oriented to the ceiling for a TM, and to the floor fot a MT
That's the problem! The 2 solutions are opposed 🙁
Is there a way to have a horizontal lobe, AND aligned accoustic cernters?
I was thinking about a solution to align the accoustic centers of the T and M
->using a sloped bafle (oriented to the floor for a TM, oriented to the ceiling for a MT)
When I want to have a horizontal main lobe, the solution is also to use a sloped bafle, but:
-oriented to the ceiling for a TM, and to the floor fot a MT
That's the problem! The 2 solutions are opposed 🙁
Is there a way to have a horizontal lobe, AND aligned accoustic cernters?
Sayonara
I found most of your statements to void of technical proof and to be based on BS. Lobing is a function of the crossovers design and the location of the speakers on baffel.
For years MTM design have ruled: Example is John Dunlavy, Duntec Labs and his other designs.
I found most of your statements to void of technical proof and to be based on BS. Lobing is a function of the crossovers design and the location of the speakers on baffel.
For years MTM design have ruled: Example is John Dunlavy, Duntec Labs and his other designs.
KYW's brief listing of advantages and disadvantages seems overly biased towards fullrange systems. No disadvantages? What about increased distortion (harmonic and doppler) over most of the frequency range, reduce dynamic capability, beaming, limited frequency range...
Just pointing out that all design possibilities have advantages and disadvantages. I think it pretty biased to list only the advantages of full range and only the disadvantages of multi-way systems. Saying "none" for the other side of the coin isn't helping other forum members much.
Just pointing out that all design possibilities have advantages and disadvantages. I think it pretty biased to list only the advantages of full range and only the disadvantages of multi-way systems. Saying "none" for the other side of the coin isn't helping other forum members much.
Thank you for these details. Now I think that with your post, and KYW's one, we have a complete review 😉
My loudspeaker will certainlt be a 2 way TM (or MT). And I'd like to solve the time alignment and lobe tilting problem.
Do you (or someone else) have an answear to my previous post?
My loudspeaker will certainlt be a 2 way TM (or MT). And I'd like to solve the time alignment and lobe tilting problem.
Do you (or someone else) have an answear to my previous post?
I like MMT, with filters configured 2.5 way, as the best of both worlds...
4th order linkwitz crossing as low as possible (1.5 khz, if the tweet is capable of this).
extra goal: baffle step corr.
I'd take two identical lowpassfilters for the mids, with an extra series inductor before the filter of the lowest M (value depends on baffle size). Unfortunately impedance reaches 4 ohms in low region.
cheers guys
4th order linkwitz crossing as low as possible (1.5 khz, if the tweet is capable of this).
extra goal: baffle step corr.
I'd take two identical lowpassfilters for the mids, with an extra series inductor before the filter of the lowest M (value depends on baffle size). Unfortunately impedance reaches 4 ohms in low region.
cheers guys
Time alignment and lobe tilting are two separate problems.
Time alignment implies Bessel (or lower) order filters and
stepping or tilting of the baffle, or a passive delay line.
For higher order filters phase alignment is the only issue and
asymmetric crossovers can be used to compensate for the
difference in acoustic path lengths to give a horizontal vertical
lobe (viewed from the side of the speaker).
🙂 sreten.
Bessel have the best step responce of any filter. The low Bessel does not roll off very fast but it will have better phase responce. That my filter of choice.
Look at the Sonus Speakers their small speakers sound great.😉
yep, bessel group delay figures are very good/constant...
But: if the distance between drivers is too big there still are significant lobing irregularities (or te be more correct: vertical dispersion irregularities) because of the drivers working together in a broader part of the audio spectrum, compared with a steeper filter of the same order.
But: if the distance between drivers is too big there still are significant lobing irregularities (or te be more correct: vertical dispersion irregularities) because of the drivers working together in a broader part of the audio spectrum, compared with a steeper filter of the same order.
"Bessel have the best step responce of any filter. "
Jewilson,
care to explain a little more?
/Peter
Jewilson,
care to explain a little more?
/Peter
Re: Answer - Coax!
It's hard for me to believe so many talented folks (like Dr. D'Appolito) have designed around a setup that has "non" advantages.
I have a set of Ariels, an MTM design by Lynn Olson. They compare favorably with systems costing many times as much money.
Kuei Yang Wang said:
It's hard for me to believe so many talented folks (like Dr. D'Appolito) have designed around a setup that has "non" advantages.
I have a set of Ariels, an MTM design by Lynn Olson. They compare favorably with systems costing many times as much money.
sreten said:
I know that they are 2 different problems. What I said is that solving one (by tilting the bafle) will worsen the other (because to solve the other, you have to tilt the bafle in the opposite direction than to solve the first)
I want to use a 1st order XO
Peter,
While no filter is perfect the Bessel has the most going for it in many different audio application. Having said that, there are times when the responce of the bessel might not quite meet an application ie. sub woofers, notch filters.
Characteristic of Bessel filters that makes them valuable to impluse responce. Very few filters are designed with square waves in mind. Most of the time, the signals filtered are sine waves, or close enough that the effect of harmonics can be ignored. If a waveform with high harmonic content is filtered, such as a square wave, the harmonics can be delayed with respect to the fundamental frequency if a Butterworth or Chebyshev response is used.
This means that a square wave is an infinite series of odd harmonics, or sinewaves, summed together to create the square shape. Obviously, if a square wave is to be transmitted without distortion, all of the harmonics - out to infinity - must be transmitted. This means that the square wave can be high pass filtered without distortion, if the 3 dB point of the filter is significantly lower than the fundamental. If the square wave is low pass filtered, however, the situation changes dramatically. Harmonics will be eliminated, producing distortion in the square wave.
The Bessel crossover designed as described above is not radically different from other common types, particularly compared to the Linkwitz-Riley. It does not maintain linear phase response at higher frequencies, but has the most linear phase. Along with fairly good magnitude flatness and minimal lobing for the even orders. It is one good choice when the drivers used have a wide enough range to support the wider crossover region, and when good transient behaviour is desired.
References
http://www.rane.com/note147.html
🙂
While no filter is perfect the Bessel has the most going for it in many different audio application. Having said that, there are times when the responce of the bessel might not quite meet an application ie. sub woofers, notch filters.
Characteristic of Bessel filters that makes them valuable to impluse responce. Very few filters are designed with square waves in mind. Most of the time, the signals filtered are sine waves, or close enough that the effect of harmonics can be ignored. If a waveform with high harmonic content is filtered, such as a square wave, the harmonics can be delayed with respect to the fundamental frequency if a Butterworth or Chebyshev response is used.
This means that a square wave is an infinite series of odd harmonics, or sinewaves, summed together to create the square shape. Obviously, if a square wave is to be transmitted without distortion, all of the harmonics - out to infinity - must be transmitted. This means that the square wave can be high pass filtered without distortion, if the 3 dB point of the filter is significantly lower than the fundamental. If the square wave is low pass filtered, however, the situation changes dramatically. Harmonics will be eliminated, producing distortion in the square wave.
The Bessel crossover designed as described above is not radically different from other common types, particularly compared to the Linkwitz-Riley. It does not maintain linear phase response at higher frequencies, but has the most linear phase. Along with fairly good magnitude flatness and minimal lobing for the even orders. It is one good choice when the drivers used have a wide enough range to support the wider crossover region, and when good transient behaviour is desired.
References
http://www.rane.com/note147.html
🙂