Magnetar said:
You tell us, your Earthquake subs are 4th order BPs. Ditto your klams. Or are you saying they are just one note fart boxes also? 😉
Obviously, any single driver or horn regardless of the number of drivers used is a monopole down in its point source (greater than ~180 deg dispersion) BW, but then so is a bipole. Ditto a dipole over some portion of its BW since AFAIK complete cancellation only occurs over a narrow BW.
GM
>Ditto a dipole over some portion
>of its BW since AFAIK complete cancellation
>only occurs over a narrow BW.
Yep. ' roomodes ' swamp out the the dreaded ' comb filtering '
>of its BW since AFAIK complete cancellation
>only occurs over a narrow BW.
Yep. ' roomodes ' swamp out the the dreaded ' comb filtering '
A page out of Linkwitz:
We can think of sound as propagating like a light ray. Thus, we can use a mirror to find the region on the side wall or ceiling where sound from the speaker might be reflected towards the preferred listening location. It depends on driver, crossover and baffle design, i.e. the polar radiation pattern, whether the region so found is illuminated by sound to any significant degree. If so, then a variety of commercial surface coverings are available to scatter and/or absorb the offending reflection.
The acoustically most problematic frequency range is below 200 Hz, because of the spatially and frequency wise irregular distribution of room resonances. Many computer programs have been written that calculate the resonant modes of a given room and recommend optimum loudspeaker and listener placements. Usually, real rooms are much more complex than the calculated models. Walls are not infinitely stiff, rooms have windows, doors, openings, suspended floors or ceilings, etc. In addition, it is the polar pattern and the acoustic source impedance of the given loudspeaker that determines which of the potential room modes are actually excited and to which degree. The usefulness of such programs is marginal at best. Likewise, recommended proportions for room length, width and height should not be taken more seriously than other proportions that may be based on visual aesthetics.
The conventional closed or vented box design, that is used for the majority of loudspeakers on the market, contributes significantly to the room problems below 200 Hz. These designs are omni-directional radiators and they tend to excite a maximum number of room resonances, particularly when located in room corners. While this adds to the perceived bass output at certain frequencies, it can lead to a falsification of the recorded material, namely when the room resonance decays more slowly than the original sound. In general, the low frequency response of omni-directional speakers in small rooms is quite non-uniform. Attempts to treat the room with absorbers will make only marginal differences unless very many absorbers or large absorbing surfaces are used. It is best to attenuate peaks in the bass response with parametric equalization. Holes in the response cannot be filled in (Ref. 1).
By far the perceptually most uniform response in the range below 200 Hz is obtained with an open-baffle, dipole or figure-of-eight radiating source. Because of its directionality, the dipole excites far fewer room resonances than an omni-directional source. The measured room response is not necessarily any smoother than that for an omni-directional source. But the perceived difference in bass reproduction is startling at first, because we are so used to hearing the irregular and booming bass of the typical box speaker in acoustically small rooms. Quickly one learns to recognize the distortion of this combination and it becomes intolerable.
For evaluating a given room and loudspeaker combination a CD is available. It contains unique sound tracks to identify room resonances and their effect upon the clarity of sound reproduction. Many of the tests require no instrumentation other than your ears.
A ripple tank experiment illustrates wave propagation and reflection in a single plane and gives an indication of the complexity of sound propagation in acoustically small spaces like living rooms.
Also see and listen to a talk about "Accurate sound reproduction from two loudspeakers in a living room" under Publications #23 and read the "Room optimized stereophonic sound reproduction" page.)
B - Loudspeaker directivity and room response
When a loudspeaker is placed in a room we hear both its direct sound, i.e. the sound which arrives via the shortest path, and the room sound due to the resonances, reverberation and reflections caused by the boundaries of the room and the objects in it. The two sounds superimpose and influence our perception of timbre, timing and spatial location of the virtual sound source. Thus, the off-axis radiation of the speaker has great influence on the naturalness of sound reproduction even when you listen on-axis and the more so, the further you sit away from the speaker.
Two basic and fundamentally different sources of sound are the monopole and the dipole radiator. The ideal monopole is an acoustically small pulsating sphere, and the ideal dipole is a back and forth oscillating small sphere. The monopole radiates uniformly into all directions, whereas the dipole is directional with distinct nulls in the plane vertical to its axis of oscillation. The 3-dimensional radiation or polar pattern of the monopole is like the surface of a basket ball, the dipole's is like two ping-pong balls stuck together. At +/-45 degrees off-axis the dipole response is L = cos(45) = 0.7 or 3 dB down, the monopole is unchanged with L = 1.
The graph above shows characteristic radiation patterns of different sound sources for very low, mid and high frequencies and with flat on-axis response.
Practical loudspeakers are neither pure monopoles nor pure dipoles except at low frequencies where the acoustic wavelengths are large compared to the cabinet dimensions.
The ideal monopole is omni-directional at all frequencies. Very few speaker designs on the consumer market approach this behavior. This type of speaker illuminates the listening room uniformly and the perceived sound is strongly influenced by the room's acoustic signature. The result can be quite pleasing, though, because a great deal of acoustic averaging of the sound radiated into every direction takes place. The speakers tend to disappear completely in the wide sound field. Unfortunately, the direct sound is maximally masked by the room sound and precise imaging is lost, unless the listening position is close to the speakers.
The typical box speaker, whether vented, band-passed or closed, is omni-directional at low frequencies and becomes increasingly forward-directional towards higher frequencies. Even when flat on-axis, the total acoustic power radiated into the room drops typically 10 dB (10x) or more between low and high frequencies. The uneven power response and the associated strong excitation of low frequency room modes contributes to the familiar (and often desired :-( ) generic box loudspeaker sound. This cannot be the avenue to sound reproduction that is true to the original.
The directional response of the ideal dipole is obtained with open baffle speakers at low frequencies. Note, that to obtain the same on-axis sound pressure level as from a monopole, a dipole needs to radiate only 1/3rd of the monopole's power into the room. This means 4.8 dB less contribution of the room's acoustic signature to the perceived sound. It might also mean 4.8 dB less sound for your neighbor, or that much more sound to you. Despite this advantage dipole speakers are often not acceptable, because they tend to be constructed as physically large panels that interfere with room aesthetics, and they seem to suffer from insufficient bass output, critical room placement and a narrow "sweet spot".
These claims are true to varying degree depending on the specific design of a given panel loudspeaker. Because of the progressive acoustic short circuit between front and rear as the reproduced signal frequency decreases, the membrane of an open-baffle speaker has to move more air locally than the driver cone of a box speaker for the same SPL at the listening position. This demands a large radiating surface area, because achievable excursions are usually small for electrostatic or magnetic panel drive. The obtained volume displacement limits the maximum bass output. Non-linear distortion, though, is often much lower than for dynamic drivers. Large radiating area means that the panel becomes multi-directional with increasing frequency which contributes to critical room placement and listening position.
If the open-baffle speaker is built with conventional cone type dynamic drivers of large excursion capability, then adequate bass output and uniform off-axis radiation are readily obtainable in a package that is more acceptable than a large panel, though not as small as a box speaker. Such speakers were built by Audio Artistry Inc. and a DIY project is described on this web site in the PHOENIX pages. This type of speaker has a much more uniform power response than the typical box speaker. Not only is its bass output in proportion to the music, because room resonance contribution is greatly reduced, but also the character of the bass now sounds more like that from real musical instruments. My hypothesis is that three effects combine to produce the greater bass clarity:
1 - An open baffle, dipole speaker has a figure-of-eight radiation pattern and therefore excites fewer room modes.
2 - Its total radiated power is 4.8 dB less than that of a monopole for the same on-axis SPL. Thus the strength of the excited modes is less.
3 - A 4.8 dB difference in SPL at low frequencies is quite significant, due to the bunching of the equal loudness contours at low frequencies, and corresponds to a 10 dB difference in loudness at 1 kHz.
Thus, bass reproduced by a dipole would be less masked by the room, since a dipole excites fewer modes, and to a lesser degree, and since the perceived difference between direct sound and room contribution is magnified by a psychoacoustic effect.,
Linwitz Page
We can think of sound as propagating like a light ray. Thus, we can use a mirror to find the region on the side wall or ceiling where sound from the speaker might be reflected towards the preferred listening location. It depends on driver, crossover and baffle design, i.e. the polar radiation pattern, whether the region so found is illuminated by sound to any significant degree. If so, then a variety of commercial surface coverings are available to scatter and/or absorb the offending reflection.
The acoustically most problematic frequency range is below 200 Hz, because of the spatially and frequency wise irregular distribution of room resonances. Many computer programs have been written that calculate the resonant modes of a given room and recommend optimum loudspeaker and listener placements. Usually, real rooms are much more complex than the calculated models. Walls are not infinitely stiff, rooms have windows, doors, openings, suspended floors or ceilings, etc. In addition, it is the polar pattern and the acoustic source impedance of the given loudspeaker that determines which of the potential room modes are actually excited and to which degree. The usefulness of such programs is marginal at best. Likewise, recommended proportions for room length, width and height should not be taken more seriously than other proportions that may be based on visual aesthetics.
The conventional closed or vented box design, that is used for the majority of loudspeakers on the market, contributes significantly to the room problems below 200 Hz. These designs are omni-directional radiators and they tend to excite a maximum number of room resonances, particularly when located in room corners. While this adds to the perceived bass output at certain frequencies, it can lead to a falsification of the recorded material, namely when the room resonance decays more slowly than the original sound. In general, the low frequency response of omni-directional speakers in small rooms is quite non-uniform. Attempts to treat the room with absorbers will make only marginal differences unless very many absorbers or large absorbing surfaces are used. It is best to attenuate peaks in the bass response with parametric equalization. Holes in the response cannot be filled in (Ref. 1).
By far the perceptually most uniform response in the range below 200 Hz is obtained with an open-baffle, dipole or figure-of-eight radiating source. Because of its directionality, the dipole excites far fewer room resonances than an omni-directional source. The measured room response is not necessarily any smoother than that for an omni-directional source. But the perceived difference in bass reproduction is startling at first, because we are so used to hearing the irregular and booming bass of the typical box speaker in acoustically small rooms. Quickly one learns to recognize the distortion of this combination and it becomes intolerable.
For evaluating a given room and loudspeaker combination a CD is available. It contains unique sound tracks to identify room resonances and their effect upon the clarity of sound reproduction. Many of the tests require no instrumentation other than your ears.
A ripple tank experiment illustrates wave propagation and reflection in a single plane and gives an indication of the complexity of sound propagation in acoustically small spaces like living rooms.
Also see and listen to a talk about "Accurate sound reproduction from two loudspeakers in a living room" under Publications #23 and read the "Room optimized stereophonic sound reproduction" page.)
B - Loudspeaker directivity and room response
When a loudspeaker is placed in a room we hear both its direct sound, i.e. the sound which arrives via the shortest path, and the room sound due to the resonances, reverberation and reflections caused by the boundaries of the room and the objects in it. The two sounds superimpose and influence our perception of timbre, timing and spatial location of the virtual sound source. Thus, the off-axis radiation of the speaker has great influence on the naturalness of sound reproduction even when you listen on-axis and the more so, the further you sit away from the speaker.
Two basic and fundamentally different sources of sound are the monopole and the dipole radiator. The ideal monopole is an acoustically small pulsating sphere, and the ideal dipole is a back and forth oscillating small sphere. The monopole radiates uniformly into all directions, whereas the dipole is directional with distinct nulls in the plane vertical to its axis of oscillation. The 3-dimensional radiation or polar pattern of the monopole is like the surface of a basket ball, the dipole's is like two ping-pong balls stuck together. At +/-45 degrees off-axis the dipole response is L = cos(45) = 0.7 or 3 dB down, the monopole is unchanged with L = 1.
The graph above shows characteristic radiation patterns of different sound sources for very low, mid and high frequencies and with flat on-axis response.
Practical loudspeakers are neither pure monopoles nor pure dipoles except at low frequencies where the acoustic wavelengths are large compared to the cabinet dimensions.
The ideal monopole is omni-directional at all frequencies. Very few speaker designs on the consumer market approach this behavior. This type of speaker illuminates the listening room uniformly and the perceived sound is strongly influenced by the room's acoustic signature. The result can be quite pleasing, though, because a great deal of acoustic averaging of the sound radiated into every direction takes place. The speakers tend to disappear completely in the wide sound field. Unfortunately, the direct sound is maximally masked by the room sound and precise imaging is lost, unless the listening position is close to the speakers.
The typical box speaker, whether vented, band-passed or closed, is omni-directional at low frequencies and becomes increasingly forward-directional towards higher frequencies. Even when flat on-axis, the total acoustic power radiated into the room drops typically 10 dB (10x) or more between low and high frequencies. The uneven power response and the associated strong excitation of low frequency room modes contributes to the familiar (and often desired :-( ) generic box loudspeaker sound. This cannot be the avenue to sound reproduction that is true to the original.
The directional response of the ideal dipole is obtained with open baffle speakers at low frequencies. Note, that to obtain the same on-axis sound pressure level as from a monopole, a dipole needs to radiate only 1/3rd of the monopole's power into the room. This means 4.8 dB less contribution of the room's acoustic signature to the perceived sound. It might also mean 4.8 dB less sound for your neighbor, or that much more sound to you. Despite this advantage dipole speakers are often not acceptable, because they tend to be constructed as physically large panels that interfere with room aesthetics, and they seem to suffer from insufficient bass output, critical room placement and a narrow "sweet spot".
These claims are true to varying degree depending on the specific design of a given panel loudspeaker. Because of the progressive acoustic short circuit between front and rear as the reproduced signal frequency decreases, the membrane of an open-baffle speaker has to move more air locally than the driver cone of a box speaker for the same SPL at the listening position. This demands a large radiating surface area, because achievable excursions are usually small for electrostatic or magnetic panel drive. The obtained volume displacement limits the maximum bass output. Non-linear distortion, though, is often much lower than for dynamic drivers. Large radiating area means that the panel becomes multi-directional with increasing frequency which contributes to critical room placement and listening position.
If the open-baffle speaker is built with conventional cone type dynamic drivers of large excursion capability, then adequate bass output and uniform off-axis radiation are readily obtainable in a package that is more acceptable than a large panel, though not as small as a box speaker. Such speakers were built by Audio Artistry Inc. and a DIY project is described on this web site in the PHOENIX pages. This type of speaker has a much more uniform power response than the typical box speaker. Not only is its bass output in proportion to the music, because room resonance contribution is greatly reduced, but also the character of the bass now sounds more like that from real musical instruments. My hypothesis is that three effects combine to produce the greater bass clarity:
1 - An open baffle, dipole speaker has a figure-of-eight radiation pattern and therefore excites fewer room modes.
2 - Its total radiated power is 4.8 dB less than that of a monopole for the same on-axis SPL. Thus the strength of the excited modes is less.
3 - A 4.8 dB difference in SPL at low frequencies is quite significant, due to the bunching of the equal loudness contours at low frequencies, and corresponds to a 10 dB difference in loudness at 1 kHz.
Thus, bass reproduced by a dipole would be less masked by the room, since a dipole excites fewer modes, and to a lesser degree, and since the perceived difference between direct sound and room contribution is magnified by a psychoacoustic effect.,
Linwitz Page
GM said:
No the horns and the Klams aren't fourth order bandpass fart boxes.
Yes the dipole sounds more realistic and 'free' in the room. See above.
freddi said:
How many, mounted where, how driven, by what, placed where, ect?
IOW dunno.
My guess would be if using four a channel close to the floor spaced tight with 1' wings driven by a SS beast used up to 300 cycles they'd need a nice 3 db per octave lift starting around 120 cycles, and high passed at 40 to keep wasted excursion down
in a way Warrior looks more appropriate - theres a few in 8ohm - does series/parallel work as well as high ohm paralleled? - did U try a shorter midrange k-tube? Reams clothespin had length ~3*diameter
freddi said:
Other then the obvious of loosing some voltage sensitivity and possible driver interaction it should work fine. You'll need a few of them to match a K15 in output. They should also be high passed if you plan on driving them real hard.
The tube was 24" long, I bought some heavy 6" and 8" PVC and plan on doing something with it. The 24" tube only sounded good pointing right at me and is crazy directional. A shorter tube shouldn't load the mid as low and that's what got me interested in using it. For now I'm liking the Lil' Buddy. Maybe this weekend I'll make a shorter tube and try it.
>does series/parallel work as well as high ohm paralleled?
If you run an impedance plot of 2 drivers in parrallel, say fs 50 Hz and 60 Hz, it will read as a single driver with fs ~55 Hz, but if they are in series the 2 'humps' stay separate.
If you run an impedance plot of 2 drivers in parrallel, say fs 50 Hz and 60 Hz, it will read as a single driver with fs ~55 Hz, but if they are in series the 2 'humps' stay separate.
I have done this experiment many times with a woofer tester.
I don't know why it works that way but it does.
I have also had it demonstrated auraly.
Much tighter, coherent bass with parrallel than series hookup.
Great thred Fred! 🙂
I wish I had more experience so I could add something meaningful, but I can tell you straight up that the 16 Warriors I have wired for 4ohms, just plain rock! I'm happy as a Klam with what I'm hearing from mine - the naturalness and realism is freaking astounding. Brian Bromberg's 300 year old standup bass never sounded better. I only have 160 4ohm watts for bass right now, but I'm looking at QSC and Crown so I can play with some lower ohm loads. It can only get better I would assume.
Anyway, I'm starting to look at more impact from the drum kit too - mostly above 300hz though. I never thought I'd see the day when two Pr170s weren't enough in this room, but geeze, I'm getting ideas about buying 6 more pairs and running another line of 8 per side next to the Warriors. Not exactly a modest approach. 🙂
I wish I had more experience so I could add something meaningful, but I can tell you straight up that the 16 Warriors I have wired for 4ohms, just plain rock! I'm happy as a Klam with what I'm hearing from mine - the naturalness and realism is freaking astounding. Brian Bromberg's 300 year old standup bass never sounded better. I only have 160 4ohm watts for bass right now, but I'm looking at QSC and Crown so I can play with some lower ohm loads. It can only get better I would assume.
Anyway, I'm starting to look at more impact from the drum kit too - mostly above 300hz though. I never thought I'd see the day when two Pr170s weren't enough in this room, but geeze, I'm getting ideas about buying 6 more pairs and running another line of 8 per side next to the Warriors. Not exactly a modest approach. 🙂
hitsware said:
IMO the small difference in phase and resonance is meaningless between a couple of cycles and a couple of degrees in a room. To spread it out makes it one, the result - with high QTS drivers on a board tere will be a peak in response at resonance, if you have many drivers spread out it can be a virtue
Interesting topic guys, I'm enjoying the discussion.
Anyway, appologies for the slight thread jack, but I was wondering if those of you using the 10" warrior's in an OB would have any hesitation crossing them higher at 500hz... assuming that the radiation pattern matches that of the horn used above 500hz.
Back on topic, I'm always impressed with how my old B&W 801's sII do on drums. That is until I hear real, un-amplified drums.
In any case it seems pretty rare/imposable to get an uncompressed drum recording. Redbook CD's have a dynamic range of 96 db and a drum kit has a dynamic range of, what, 120+db's?
SACD's have enough dynamic range, but as Magnetar said, 99.999999% of play back systems are not capable of that kind of clean output. It would be pointless to do an uncompressed recording as the average level would be so low on most hi-fi's.
Anyway, appologies for the slight thread jack, but I was wondering if those of you using the 10" warrior's in an OB would have any hesitation crossing them higher at 500hz... assuming that the radiation pattern matches that of the horn used above 500hz.
Back on topic, I'm always impressed with how my old B&W 801's sII do on drums. That is until I hear real, un-amplified drums.
In any case it seems pretty rare/imposable to get an uncompressed drum recording. Redbook CD's have a dynamic range of 96 db and a drum kit has a dynamic range of, what, 120+db's?
SACD's have enough dynamic range, but as Magnetar said, 99.999999% of play back systems are not capable of that kind of clean output. It would be pointless to do an uncompressed recording as the average level would be so low on most hi-fi's.
I don't agree, but it is a moot point since (for practical purposes)to make much of array at all something has to be seriesed.
Why? SS poweramps are cheap secondhand, and for LF, they're all that's neccessary, so buy a few and have fun.hitsware said:
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