My primary mentor on horns is Bjorn Kolbrek, who has the best simulations I know of. He guided the parameter selection for the AH425 and provided the hard-to-find information about the exit angle of the Altec/GPA 288 (which is 7~8 degrees, depending where you measure).
From what I can tell, there's a tradeoff between "smooth loading diaphragm loading vs frequency" and "constant-directivity" horns. The conical and modified-conical horns (with a smoothed transition between compression driver and horn flare) are optimized for constant energy over the intended radiation angle, commonly 90 degrees, but other radiation angles are common too. Conical and near-conical horns require a transition region between the (near) plane wave coming out of the compression driver and the spherical wave that expands through the conical portion of the horn. This transition region is accomplished with either a sharp or gradual bend in the throat of the horn, close to where the compression driver and horn-throat meet, and if sharp enough, this transition region creates diffraction, which in turn creates reflections in the time domain and ripples in the frequency response of the horn.
So conical and near-conical horns may require in-band equalization, and occasionally in-band notch filters. However, if diffraction is severe enough, equalization may not work, since the response ripples will be different at different angles of emission, with no single EQ curve applicable to the entire horn. Conicals and near-conicals also require a gradual HF boost to offset the drooping power response of the compression driver - with some compression drivers (typically those with titanium diaphragms), this boost is applied in the breakup region. Mylar and plastic diaphragms have more self-damping than metal diaphragms, so they are better candidates for applications requiring HF boost.
As a far as I can tell, the LeCleac'h and Holland & Newell horns do not prioritize pattern control (they are not constant-directivity), but optimize diaphragm loading over the working bandwidth. This results in less need for in-band equalization, and if the horn is well-designed and exit angles and horn-throat angles are well-matched, minimizing diffraction in the throat region. The impulse response I've seen from the AH425 is the shortest I have seen from any horn, which tracks with the overall goals of the Newell and Holland project.
The tradeoff is a narrowing polar response at higher frequencies. The AH425 mimics a direct-radiator about 4" across in terms of its polar response; the dropoff with angle is very smooth (and sounds it), but a supertweeter is definitely needed, for dispersion reasons alone. Since I am using a compression driver with a large aluminum diaphragm (about 3") that has the first breakup above 7 Khz, that's another reason to use a supertweeter.
Here's a simulation that Bjorn Kolbrek did that compares the AH425 versus a conical. It shows the resistive versus reflected energy as seen from the compression driver diaphragm. Like a radio antenna, an ideal horn sends all its power out the device and into the environment, reflecting nothing back to the source. Any power reflected back to the source is wasted, and worse, creates a reflection off the rigid diaphragm, creating ripples in the time and frequency domains.
The thin black trace is the resistive part of the AH425, and the thin red trace is the reflected energy (as a percentage). The transition is around 500 Hz, as you would expect. The curves are telling us that the horn ceases to work below the cutoff frequency. Above 700 Hz, more than 90% of the energy goes into the horn, and less than 10% is reflected. That was one of the key design goals of the AH425 project, and that goal is reflected in the real-world measurements of the AH425.
The heavy black trace is the resistive part of a conical horn, and heavy red trace is the reflected energy. Note the uneven diaphragm loading versus frequency. As a result of diffraction in the throat, the horn doesn't present a resistive load to the diaphragm until you get to frequencies above 3~4 kHz.
From what I can tell, there's a tradeoff between "smooth loading diaphragm loading vs frequency" and "constant-directivity" horns. The conical and modified-conical horns (with a smoothed transition between compression driver and horn flare) are optimized for constant energy over the intended radiation angle, commonly 90 degrees, but other radiation angles are common too. Conical and near-conical horns require a transition region between the (near) plane wave coming out of the compression driver and the spherical wave that expands through the conical portion of the horn. This transition region is accomplished with either a sharp or gradual bend in the throat of the horn, close to where the compression driver and horn-throat meet, and if sharp enough, this transition region creates diffraction, which in turn creates reflections in the time domain and ripples in the frequency response of the horn.
So conical and near-conical horns may require in-band equalization, and occasionally in-band notch filters. However, if diffraction is severe enough, equalization may not work, since the response ripples will be different at different angles of emission, with no single EQ curve applicable to the entire horn. Conicals and near-conicals also require a gradual HF boost to offset the drooping power response of the compression driver - with some compression drivers (typically those with titanium diaphragms), this boost is applied in the breakup region. Mylar and plastic diaphragms have more self-damping than metal diaphragms, so they are better candidates for applications requiring HF boost.
As a far as I can tell, the LeCleac'h and Holland & Newell horns do not prioritize pattern control (they are not constant-directivity), but optimize diaphragm loading over the working bandwidth. This results in less need for in-band equalization, and if the horn is well-designed and exit angles and horn-throat angles are well-matched, minimizing diffraction in the throat region. The impulse response I've seen from the AH425 is the shortest I have seen from any horn, which tracks with the overall goals of the Newell and Holland project.
The tradeoff is a narrowing polar response at higher frequencies. The AH425 mimics a direct-radiator about 4" across in terms of its polar response; the dropoff with angle is very smooth (and sounds it), but a supertweeter is definitely needed, for dispersion reasons alone. Since I am using a compression driver with a large aluminum diaphragm (about 3") that has the first breakup above 7 Khz, that's another reason to use a supertweeter.
Here's a simulation that Bjorn Kolbrek did that compares the AH425 versus a conical. It shows the resistive versus reflected energy as seen from the compression driver diaphragm. Like a radio antenna, an ideal horn sends all its power out the device and into the environment, reflecting nothing back to the source. Any power reflected back to the source is wasted, and worse, creates a reflection off the rigid diaphragm, creating ripples in the time and frequency domains.
The thin black trace is the resistive part of the AH425, and the thin red trace is the reflected energy (as a percentage). The transition is around 500 Hz, as you would expect. The curves are telling us that the horn ceases to work below the cutoff frequency. Above 700 Hz, more than 90% of the energy goes into the horn, and less than 10% is reflected. That was one of the key design goals of the AH425 project, and that goal is reflected in the real-world measurements of the AH425.
The heavy black trace is the resistive part of a conical horn, and heavy red trace is the reflected energy. Note the uneven diaphragm loading versus frequency. As a result of diffraction in the throat, the horn doesn't present a resistive load to the diaphragm until you get to frequencies above 3~4 kHz.
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Hi Lynn,
This simulation is great, very revealing. A question though, was the conical profile optimized for transitioning the wave front from plane to spherical? And if yes, which was the method? I recall Earl Geddes argued that oblate spheroid was the only geometrical solution for this transition. This is what was used?
Also, LeCleac'h has an intrinsic mouth round-over due to the actual profile, was the conical treated the same?
Thanks,
Florin
This simulation is great, very revealing. A question though, was the conical profile optimized for transitioning the wave front from plane to spherical? And if yes, which was the method? I recall Earl Geddes argued that oblate spheroid was the only geometrical solution for this transition. This is what was used?
Also, LeCleac'h has an intrinsic mouth round-over due to the actual profile, was the conical treated the same?
Thanks,
Florin
I don't recall if the conical was fully optimized - like an OS - or the simpler constant-radius transition, like the Quadratic Throat Waveguide. The degree of roughness directly correlates to the sharpness of the planewave-to-spherical transition.
It was clear in the simulation that an intentional diffraction in the throat, although a useful (and common) way to create the desired polar pattern, has the penalty of creating a large reflection. The conical horn simulated above was much better than the JBL Bi-Radial and Altec Manta-Ray horns, where the diffraction throat is much sharper.
In a LeCleac'h with the right T ratio, the roughness can be brought down to nearly zero (the AH425 has a T ratio of 0.707). The penalty, like the similar Newell & Holland horn, is a gradual increase in directivity at higher frequencies.
From what I could see in the simulations, there seemed to be a general rule: directivity control (using diffraction throats) goes in the opposite direction to time and frequency optimization. Attempts to optimize one would degrade the other two, which follows the conclusions of Newell and Holland (Loudspeakers for Music Recording and Reproduction, pp. 108 through 113).
The fine detail and edges of the polar pattern (I need to dig up more of Bjorn's sims) are different as well. The conical has a sharp edge with ripples (fingering), while the LeCleac'h has a soft edge but narrower overall directivity. The polar patterns looked like a high-gain Yagi antenna (for conical) versus a low-gain cardioid-like pattern for the LeCleac'h.
Throat diffraction has negative effects in the polar, time, and frequency domains, and shows up in simulations and real-world measurements.
It was clear in the simulation that an intentional diffraction in the throat, although a useful (and common) way to create the desired polar pattern, has the penalty of creating a large reflection. The conical horn simulated above was much better than the JBL Bi-Radial and Altec Manta-Ray horns, where the diffraction throat is much sharper.
In a LeCleac'h with the right T ratio, the roughness can be brought down to nearly zero (the AH425 has a T ratio of 0.707). The penalty, like the similar Newell & Holland horn, is a gradual increase in directivity at higher frequencies.
From what I could see in the simulations, there seemed to be a general rule: directivity control (using diffraction throats) goes in the opposite direction to time and frequency optimization. Attempts to optimize one would degrade the other two, which follows the conclusions of Newell and Holland (Loudspeakers for Music Recording and Reproduction, pp. 108 through 113).
The fine detail and edges of the polar pattern (I need to dig up more of Bjorn's sims) are different as well. The conical has a sharp edge with ripples (fingering), while the LeCleac'h has a soft edge but narrower overall directivity. The polar patterns looked like a high-gain Yagi antenna (for conical) versus a low-gain cardioid-like pattern for the LeCleac'h.
Throat diffraction has negative effects in the polar, time, and frequency domains, and shows up in simulations and real-world measurements.
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Hi Lynn,
I also have followed BTA thread and also made system based on these ideas /albeit not strictly/.
It is big WTW with AE's lambdas TD12M and 1.4 inch compression driver with 3 inch diagram. /18s titanium nitrid/ Horn is asymmetrical - so at 500hz XO CTC is small enough to be "point source".
I've also added Supertweeter /which off course cannot be integrated without lobing/ and I had great deal of difficulty with its implementation and every time it was a question whether adding STW is positive VS running CD all way up.
Contrary to your finding I've found crossing to STW quite sensitive and problematic. I've tried many tweeters including 3/4 dome, compression driver with small horn and ribbon tweeter with and without small horn. /I've ended up with the last at ca. 10k/.
Would you be so kind to share your observations about adding STW, of course to the extent you feel comfortable with it, because of your upcoming speaker project?
Many thanks
I also have followed BTA thread and also made system based on these ideas /albeit not strictly/.
It is big WTW with AE's lambdas TD12M and 1.4 inch compression driver with 3 inch diagram. /18s titanium nitrid/ Horn is asymmetrical - so at 500hz XO CTC is small enough to be "point source".
I've also added Supertweeter /which off course cannot be integrated without lobing/ and I had great deal of difficulty with its implementation and every time it was a question whether adding STW is positive VS running CD all way up.
Contrary to your finding I've found crossing to STW quite sensitive and problematic. I've tried many tweeters including 3/4 dome, compression driver with small horn and ribbon tweeter with and without small horn. /I've ended up with the last at ca. 10k/.
Would you be so kind to share your observations about adding STW, of course to the extent you feel comfortable with it, because of your upcoming speaker project?
Many thanks
Well, if the supertweeter is off to one side, then imaging will be somewhat unstable, since the listener will hear a crossover with different phasing for each ear. Even a slight movement of a few inches to the left or right will shift the relative phasing between horn and supertweeter.
In principle, a supertweeter located directly above the horn will have the same phasing issues, since any supertweeter (that isn't coaxial) will be several wavelengths apart at the crossover frequency. If the supertweeter is directly above the horn, though, at least there won't be left/right differences between the ears. What happens instead is a vertical null that comes and goes with shifts in seating height. If the null is at 7 kHz or above, it creates a false impression of additional image height, but not a coloration that is tonal in character. If the null is 5 kHz or lower, tonal colorations are heard, and if the null is 3 kHz or lower, then more severe colorations will arise.
A supertweeter appears to benefit from a 3rd or 4th-order highpass crossover, despite conventional wisdom. The lower the supertweeter reaches into the region where pitch is audible the more noticeable it seems to be - and a supertweeter should never be be directly audible as a driver. All switching it on and off should do is add a touch of sparkle and air at the top - there should never be any tonal shift to the loudspeaker as whole - if there is, the supertweeter is too loud, too peaky, or has too much energy below 7 kHz. It has to remembered that very little spectral energy is above 7~10 kHz, and a moderate-slope crossover has to work against the steep spectral tilt of the original program material.
A simple way to test this is listen to the supertweeter alone - if you can hear what sounds like music coming through, the crossover isn't steep enough, or is too low, or both. All you should hear is an occasional transient - basically, clicks, and not much else. It should like it is doing almost nothing when you listen to it by itself.
Regarding the comment that a 500hz XO CTC is small enough to be "point source", I'm not sure I agree. This has to be determined by subjective experience - preferably with broadband program material like massed chorus, or large-scale symphonic music. Some driver layouts will disappear into a single virtual point source, and others won't, and it doesn't always agree with theory.
I've had bad experiences with large MTM's - it was a struggle to get the 5.5" drivers of the Ariel to sound like a single coherent driver. I've yet to hear a large WMTMW or large WTW sound coherent, regardless of crossover, and I've heard lots of them at hifi shows and at friend's homes. Small phasing differences - on the order of 10~20 degrees between drivers - that are acceptable in a compact MTM sound quite unpleasant in a larger system, and the higher the top woofer is off the floor, the worse it seems to be.
A subtle problem for large WMTMW and WTW arrays is the floor image is always present - carpets absorb less than 1 dB below 5 kHz - and the floor image will couple to the lower woofer more efficiently than the upper woofer, which unbalances the WMTMW or WTW pairing. In effect, the floor image adds deep bass to the lower woofer, while the upper woofer sounds thinner, since it doesn't couple as well to the floor image.
It could also be purely subjective; bass coming from above ear height sounds weird and unnatural to me - it's something I try to avoid in my own designs. However, personal tolerance for this seems to differ. Plenty of other audiophiles enjoy large WMTMW and large WTW systems, so it could just be the way I hear things.
In principle, a supertweeter located directly above the horn will have the same phasing issues, since any supertweeter (that isn't coaxial) will be several wavelengths apart at the crossover frequency. If the supertweeter is directly above the horn, though, at least there won't be left/right differences between the ears. What happens instead is a vertical null that comes and goes with shifts in seating height. If the null is at 7 kHz or above, it creates a false impression of additional image height, but not a coloration that is tonal in character. If the null is 5 kHz or lower, tonal colorations are heard, and if the null is 3 kHz or lower, then more severe colorations will arise.
A supertweeter appears to benefit from a 3rd or 4th-order highpass crossover, despite conventional wisdom. The lower the supertweeter reaches into the region where pitch is audible the more noticeable it seems to be - and a supertweeter should never be be directly audible as a driver. All switching it on and off should do is add a touch of sparkle and air at the top - there should never be any tonal shift to the loudspeaker as whole - if there is, the supertweeter is too loud, too peaky, or has too much energy below 7 kHz. It has to remembered that very little spectral energy is above 7~10 kHz, and a moderate-slope crossover has to work against the steep spectral tilt of the original program material.
A simple way to test this is listen to the supertweeter alone - if you can hear what sounds like music coming through, the crossover isn't steep enough, or is too low, or both. All you should hear is an occasional transient - basically, clicks, and not much else. It should like it is doing almost nothing when you listen to it by itself.
Regarding the comment that a 500hz XO CTC is small enough to be "point source", I'm not sure I agree. This has to be determined by subjective experience - preferably with broadband program material like massed chorus, or large-scale symphonic music. Some driver layouts will disappear into a single virtual point source, and others won't, and it doesn't always agree with theory.
I've had bad experiences with large MTM's - it was a struggle to get the 5.5" drivers of the Ariel to sound like a single coherent driver. I've yet to hear a large WMTMW or large WTW sound coherent, regardless of crossover, and I've heard lots of them at hifi shows and at friend's homes. Small phasing differences - on the order of 10~20 degrees between drivers - that are acceptable in a compact MTM sound quite unpleasant in a larger system, and the higher the top woofer is off the floor, the worse it seems to be.
A subtle problem for large WMTMW and WTW arrays is the floor image is always present - carpets absorb less than 1 dB below 5 kHz - and the floor image will couple to the lower woofer more efficiently than the upper woofer, which unbalances the WMTMW or WTW pairing. In effect, the floor image adds deep bass to the lower woofer, while the upper woofer sounds thinner, since it doesn't couple as well to the floor image.
It could also be purely subjective; bass coming from above ear height sounds weird and unnatural to me - it's something I try to avoid in my own designs. However, personal tolerance for this seems to differ. Plenty of other audiophiles enjoy large WMTMW and large WTW systems, so it could just be the way I hear things.
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"I've had bad experiences with large MTM's - it was a struggle to get the 5.5" drivers of the Ariel to sound like a single coherent driver. I've yet to hear a large WMTMW or large WTW sound coherent, regardless of crossover, and I've heard lots of them at hifi shows and at friend's homes. Small phasing differences - on the order of 10~20 degrees between drivers - that are acceptable in a compact MTM sound quite unpleasant in a larger system, and the higher the top woofer is off the ground, the worse it seems to be. It could be that bass coming from above ear height just sounds weird and unnatural to me."
What about 70-100hz crossover point? (2x altec 416 and Tannoy 10" gold in the middle)
What about 70-100hz crossover point? (2x altec 416 and Tannoy 10" gold in the middle)
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The last post timed out, so I'd like add this point: listen to each woofer by itself (run them full range), quickly switch between them, and see if they have the same tonal character. I'll bet they don't, even if carefully pair-matched.
That's the effect of the floor image. Moving a woofer just a few inches vertically can noticeably affect the subjective balance of a woofer; 6" + 6" + horn size is a much larger vertical distance.
If the woofers sound different - as I would expect - then the underlying advantage/principle of a D'Appolito array is lost, since the drivers are no longer phase-matched (phase follows frequency response in a minimum-phase system).
We get into the much deeper waters of independently equalizing the two woofers so they phase-track each other through the crossover region. I'm not sure a passive method exists, since the "warmer" sounding woofer is effectively more efficient in the 30~100 Hz region, and there's no good way of passively reducing its efficiency in that range. At a wild guess, it might take a separate power amplifier for each woofer, along with independent digital equalization, in order to offset the differential effect of the floor image so the woofers can be brought into mutual phase-tracking.
What if the tonal difference is ignored, and the woofers share a common lowpass filter? That means there is a phase difference between the two in the crossover region, which tilts the polar pattern. The crossover is no longer a pure D'Appolito array, but something else, and the model start to break down, unless you include the floor image as part of the overall design (which I would recommend).
That's the effect of the floor image. Moving a woofer just a few inches vertically can noticeably affect the subjective balance of a woofer; 6" + 6" + horn size is a much larger vertical distance.
If the woofers sound different - as I would expect - then the underlying advantage/principle of a D'Appolito array is lost, since the drivers are no longer phase-matched (phase follows frequency response in a minimum-phase system).
We get into the much deeper waters of independently equalizing the two woofers so they phase-track each other through the crossover region. I'm not sure a passive method exists, since the "warmer" sounding woofer is effectively more efficient in the 30~100 Hz region, and there's no good way of passively reducing its efficiency in that range. At a wild guess, it might take a separate power amplifier for each woofer, along with independent digital equalization, in order to offset the differential effect of the floor image so the woofers can be brought into mutual phase-tracking.
What if the tonal difference is ignored, and the woofers share a common lowpass filter? That means there is a phase difference between the two in the crossover region, which tilts the polar pattern. The crossover is no longer a pure D'Appolito array, but something else, and the model start to break down, unless you include the floor image as part of the overall design (which I would recommend).
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Speaker showed is early Kevin Brooks creation. I think around 12-15 Cu. ft , originaly with Tad 1602 wofers and 260hz tractrix horn in the middle with Tad TD4001. Now, I have Tad 4001 for a few years already and know that 4001 + relatively small tractrix horn =headache .It just doesn't work. The cab built in Tannoy tradition with Tannoy grill cloth begs for 15" Tannoy but those are fetching obscene amount of money. I figured out that small Tannoy 10" in 2cuft closed horn compartment with biamped HE woofers would get pretty close if not better than single 15" gold. If not , a single 416 or 515B would do nicely in that big cab (although it would probably be a waste to cross 515B at 70-100Hz. I have lots of ideas about that cabs , also with horn arrays fitted . Sorry for OT post just the remark about big MTM not sounding natural caught my attention.
I tried for many years to get Tannoy drivers on an OEM basis and the answer was always no. It's not easy getting them for replacement purposes; you have to prove to the factory you already have a dead Tannoy before they will cut loose a replacement driver. They are dead set against an OEM market developing as far as I could tell. Which is unfortunate, because the Tannoy really is a unique coaxial driver with a very good integral horn assembly.
I listened to a lot of small-format horns before I gave up on them. I suspect they don't work very well below 2~2.5 kHz - they might measure OK, but they sound strained and harsh below that frequency, even more than ordinary 1" soft-dome tweeters. Large-format drivers can be coaxed to much lower frequencies, but still demand low-diffraction horns - or the unobtanium multicells. Sectoral, MantaRay, and Bi-Radial horns with a diffraction "pinch" in the throat are all hopeless - once diffraction happens, no amount of EQ magic can undo it, and the horn-throat is the worst possible location for diffraction.
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I noticed you had positive things to say about the audiokinesis stuff earlier in this thread. Isn't that a small-format horn crossed around 1.2khz or so? Is that still strained sounding to you?
For large format wide range drivers, in 15 inch land, you might want to audition a pair of Audio Nirvana full range devices. The whizzer is actually a small relatively fast flare horn, connected to the end of the voice coil. Tremendously transparent driver.
Of course, if you would all just get busy learning how to EnABL, many of these crossover woes would fall to insignificance.....
Bud
Of course, if you would all just get busy learning how to EnABL, many of these crossover woes would fall to insignificance.....
Bud
The Tannoy concept seem good at first sight. but if you consider the outer cone moving in relation to the horn lip, it is not difficult to figure out there is going to be something sounding funny.
I have been playing around with small format horns/wave guides, and I agree they sound somewhat stressed. But I still hesitate to conclude whether it's the horn or whether it's revealing a problem somewhere else in the system.
Thanks Lynn and everybody for thoughts and comments.
Actualy i never listened my system without top woofer - and i certainly will after your comments.
My STW is crossed very sharply at ca 10k and there is only zing zang cang - no music at all. Even then efect of supertweeters polar responses to spatial presentation was very unsubtle and very very hard to choose which one is correct. Even presentation without STW at all has its magic. Ultimately its up to program material and subjective impression.
Actualy i never listened my system without top woofer - and i certainly will after your comments.
My STW is crossed very sharply at ca 10k and there is only zing zang cang - no music at all. Even then efect of supertweeters polar responses to spatial presentation was very unsubtle and very very hard to choose which one is correct. Even presentation without STW at all has its magic. Ultimately its up to program material and subjective impression.
Have you time-aligned the supertweeter? To a first approximation, put the supertweeter diaphragm about an inch/25mm behind the diaphragm of the compression driver, which is close to the back of the compression-driver assembly. Make sure the path to the listener is unobstructed and reasonably free of nearby reflecting surfaces (damp the surfaces with F13-grade wool felt if necessary).
More accurately, the acoustic center of the compression driver is about 1/4 to 1/2 wavelength (at the upper crossover frequency) behind the physical diaphragm. What moves it back further in space (away from the listener) is the combined lowpass of the horn+driver and the electrical lowpass of the horn crossover - the group delay of the horn+driver and lowpass filter are additive.
Although some people like to line up the horn mouth and front face of the supertweeter, this grossly misaligns the supertweeter - by several wavelengths - which is not good at all. The misalignment is perceived as incoherent and "spiky" sounding - in other words, the supertweeter draws attention to itself, and not in a good way.
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I decided to struggle with original arrangement before trying to change to Tannoy and supporting woofers. I'm not sure how 100dB woofer section will align itself(Bi-amping) with 92 dB Tannoy 10" , time will tell. The problem is handling of the speaker where weight of one is probably more than 300 lBs.
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yes i have it time aligned. I use DSP /no kosher, i know
/ so i can delay. In my setup everything is flush so no diffraction problem. I'm talking about different polar characteristic of different tweeters. Even if you setup them that each is ruler flat - each sound very different. 3/4 dome can sound like rear ambient tweeter on some speakers, ribbon sound different etc... In this context it is hard to speak about which is better it is just different. This is why i was interested in your implementation.BTW, I was so interested about your Appolito note, that i make switch on wire that i can switch upper woofer off/on from listening position. Off course there was 3db difference in level but no other negative effect of WTW pattern. But i have woofers as close as possible. From 80cm and up it sound like single source. It is important to lowpass woofer very steep /48db/oct in my case/ otherwise lobing from out of band is problem. So not very doable passive and probably not your cup of tea.
many thanks and sorry for non-native English
Tomas
Yes i tried and i know it should be matched. But when you limit dispersion of tweeter so it has /at xo/ directivity of horn with 1,4 inch throat /no diffraction slot/ - there is almost no audible contribution of such tweeter over horn alone. Im talking about crossing at 10k and up. So STW to be actualy audible, it has to have wider dispersion over "extended mid" horn. How much wider is THE question. And i think this debate is very old - i read somewhere that even Greg Timber like Everest /do not know which one/ without STW more... Off course you need compression driver capable of UHF.
Basically im talking about solution to UHF for system with large diagram CD.
/Im assuming it is capable of UHF/
U can use STW - means problem with lobing and choosing right polar for STW
U can use diffraction slot - means HOM
Or and this is way that investigating right now. - Mimic the perceived inroom timbre of system with STW - without it by EQ. I do it by ear on pink noise with instant switching STW vs just CD + eq. This off course lead to non flat on axis response - but actual perceived timbre can be very very similar.
Actually i cannot be capable to tune CD UHF right without listening to STW to same time.
I hope that this post is not very misleading and hard to read. And sorry for my English.
Tomas
CD - compression driver
UHF - ultrahigh frequency
STW - supertweeter
Basically im talking about solution to UHF for system with large diagram CD.
/Im assuming it is capable of UHF/
U can use STW - means problem with lobing and choosing right polar for STW
U can use diffraction slot - means HOM
Or and this is way that investigating right now. - Mimic the perceived inroom timbre of system with STW - without it by EQ. I do it by ear on pink noise with instant switching STW vs just CD + eq. This off course lead to non flat on axis response - but actual perceived timbre can be very very similar.
Actually i cannot be capable to tune CD UHF right without listening to STW to same time.
I hope that this post is not very misleading and hard to read. And sorry for my English.
Tomas
CD - compression driver
UHF - ultrahigh frequency
STW - supertweeter
Lynn ... can you give me an estimate for a conical window in front of a supertweeter so I can space horns either above or below and be relatively assured of a clear pathway? I thought an included angle of 30 degrees would be sufficient but even that makes for a large spread between adjacent horns. Crossover would be => than 8kHz.
Thanks, Zene
Thanks, Zene
Hello Tomas
I run mine both ways with a TW/STW and with out. I have two systems that have tweeters integrated that sound good one an old large format monitor JBL4344 and the now generation 1400 Arrays with Be drivers. I also have an HT set-up with 2435's on PTH1010 waveguides with no TW/STW.
No matter how you do it it's compromise. Both of my systems are not time aligned and frankly I don't see the point. Time aligned is a 1 point in space solution.
The Arrays match the Horizontal dispersion at crossover as does the 4344. The Array more so than the 4344. Both seem to work pretty well.
I am not buying that until there is a definitive measurement for comparison. The 9800, 9900 6600 Everest 2 and the Arrays all use a " diffraction" type horn. I don't hear to many people complaining about how harsh they sound. I don't think it's as simple as just using a diffraction slot it's more how it's done that determines how audible any issues are from the "slots"
Rob
I run mine both ways with a TW/STW and with out. I have two systems that have tweeters integrated that sound good one an old large format monitor JBL4344 and the now generation 1400 Arrays with Be drivers. I also have an HT set-up with 2435's on PTH1010 waveguides with no TW/STW.
No matter how you do it it's compromise. Both of my systems are not time aligned and frankly I don't see the point. Time aligned is a 1 point in space solution.
The Arrays match the Horizontal dispersion at crossover as does the 4344. The Array more so than the 4344. Both seem to work pretty well.
I am not buying that until there is a definitive measurement for comparison. The 9800, 9900 6600 Everest 2 and the Arrays all use a " diffraction" type horn. I don't hear to many people complaining about how harsh they sound. I don't think it's as simple as just using a diffraction slot it's more how it's done that determines how audible any issues are from the "slots"
Rob
