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Most excellent. This is progress in the right direction. You are saving me a whole bunch of work at the keyboard, and this should read very linear. I will dispense with further questions, and provide my 2 cents on the issue. My basic overview is thus:"You can't have yer' cake and eat it too".Yep, the only way the well damped material can convert the sound energy into heat is movement. Insulation fibers are the easiest to understand in this regard. The do flex when encountering sound waves, and ...
A very good actual example of this is exists in the response curve for the W18E driver on the SEAS page. The surround material thickness and type determines the response slightly above 2500hz. The relative dip between 2500hz and cone resonance at 4200hz is the surround material moving out of phase with the driver. However, this also means that the CONE of the W18 driver remains a piston up to this frequency range. The stiff edge of the cone at high acceleration pushes the surround into "whiplash".
If you want to use a 1st order acoustic crossover with a 7" driver at 2500hz, that cone needs to have flexible material, in a flexible cone to absorb the sound energy. It won't have resonance.
QuoteBetter drivers... there we get into my opinion that "stiff enough" drivers with good damping characteristics are better than stiffer drivers that don't have self-damping. What truly stiff drivers have you actually measured/tested/implemented/used? What's your a/b comparison?
Better drivers... there we get into my opinion that "stiff enough" drivers with good damping characteristics are better than stiffer drivers that don't have self-damping.
John, Thanks for the commentary but it's uncool to post a commercial for your speakers in another manufacturer's circle. In fairness, Dave should edit your last paragraph. I'm not big on rules but this one seems to make sense. Cheers,Jack
When measured, the Accuton C95 nasty response bubble around 4.2khz is darn near on par with the SEAS W18 drivers. However, there is something else happening here. I really don't know what the issue IS, but when my CLIO jig is working, it will be explored further.I am not surprised at the very small quantity of Accuton drivers in the hifi marketplace. They are expensive - very expensive. Given the quantity of production for hifi speakers and the necessary profit margins, using Accuton is a very quest ...
Quote from: skrivisWith a cone, the surround is in the right place to control the bad behavior. With a dome, there's nothing there to control it...I believe this comment hits the target very close to the center. I believe the difference between many good tweeters (fabric or metal) is the surround. The very valuable dampening of a surround on cone drivers is never overlooked - especially on very well damped (i.e. soft) cones. As the frequency rises, such cones outer edge will begin to flop in the opposite direction of the inner cone movement. The well damped surround is obviously needed to control the loose floppy motion of the outer edge of the driver cones.
With a cone, the surround is in the right place to control the bad behavior. With a dome, there's nothing there to control it...
Stuart, the problem is that the resonances in a soft dome will be much higher in amplitude within the useful bandwidth of the speaker. A rigid structure vibrates less and the resonant energy is disipated as a spike outside of the audible range. But with a soft dome, it will be oscillating within the bandwidth. So, a soft dome will lose some detail and will also add resonances, though they aren't all that offensive, not like the oilcan resonance would be *if* it were in the audible bandwidth. This is ...
How are the resonances from a damped soft dome greater in magnitude than those with a metal dome? A damped system tends to have a low Q, while things like metal domes will have a very high Q at resonance.
Please explain "the resonant energy is disipated as a spike outside of the audible range."
So you think that a metal dome can put out tons of trash at 30KHz and it won't have any effect because it's beyond the audible range? Ever heard of intermodulation?
It's especially a concern with the Xd's because I don't know the quality of the DEQX digital implementation and how much hi-freq trash it puts out. The Class D amps will likely put out a bunch of noise too, and excite any resonances in the metal dome tweeters.
Floyd O'Toole/NRC-inspired designers? Well.... if that's your cup of tea, that's fine.
Defined "damped". You mean "lossy"? A fabric dome tweeter isn't really "damped" as I define the word. A cone that is sprayed with a resin or something that is designed to inhibit resonance is "damped". How well it is "damped" depends on how it is done. Fabric is not rigid, therefore it vibrates and undulates easily. Rather than being a high Q resonant spike, the undulations cause wider bandwidth resonances, aka distortion IN bandwidth. Yes, you could argue that a 10dB spike in energy could be problematic except that you can't hear it. And each year of your life puts it further away from audibility.
n"Quote from: skrivisPlease explain "the resonant energy is disipated as a spike outside of the audible range."IOW, the only real tendency to resonate in a metal driver is at actual one resonance peak. It has very low loss. Sure, there might be some small resonances in the audible bandwidth, but they will be very low compared to those of a fabric design. With fabric, however, you have flexibility combined with tensile strength, the same thing that plagues kevlar. It *will* resonate, but across a wide bandwidth and it will be in the audible range mostly, unlike a metal tweeter.
Quote from: John Ashman you think that a metal dome can put out tons of trash at 30KHz and it won't have any effect because it's beyond the audible range? Ever heard of intermodulation?So you think a soft dome resonating throughout the audible range won't have any effect on it? The fabric isn't dissipating all that much as heat, it's dissipating it as sound. Fabrics will have higher distortion figures than metal drivers. I don't hear the peak, at least in better metal tweeters. I've
you think that a metal dome can put out tons of trash at 30KHz and it won't have any effect because it's beyond the audible range? Ever heard of intermodulation?
A lot of people who haven't heard Xd have this "concern". Those who have heard it do not. At this point, you're wildly accusing new technology based on your perceptions, not knowledge of the design involved. I can tell you this, actively amping the tweeter sure beats running through a bunch of resistors and capacitors.
Yep, pretty much. Not always, but at least they haven't lost site of the ideal goal of a speaker - transparency. Most "high-end" speaker companies are just screwing around like Baskin-Robbins does with ice cream. Thank goodness too, or I'd be forced to listen to listen to SETs with horns and that would be horrifying.
In the case of real diaphragm materials, yes, damped equals lossy.
The end result is a dome that is rigid yet has good internal damping. It doesn't go into uncontrolled high Q breakup like a metal dome will.
We don't yet have the perfect material. So metal is very stiff, but not perfectly stiff. It also exhbits very poor internal damping. (This is why they make bells out of metal instead of coated fabric.)
Metal diaphragms _will_ exhibit breakup, since we're not dealing with perfectly stiff materials. When they do, there isn't any internal damping to control the resonance.
You'll see the center of the dome start to misbehave because it's farthest from the control of the voice coil. Since metal isn't internally damped, the breakup will be very well propagated to the edge (the voice coil), then reflected back into the dome, etc.
Just because it isn't directly audible does not mean you won't hear its effect.
Kevlar composite cones have some limitations, but I'm not seeing how flexibility combined with tensile strength are responsible.
So if I make a cone out of something flexible with little tensile strength I won't have any problems? Or do I want something stiff with no tensile strength?
You didn't answer my question, but we'll let that pass.
I'm not convinced that a soft dome is going to resonate or breakup throughout the audible range. Furthermore, any such resonance will be of lower Q and likely less obnoxious.
Low amounts of distortion across a wide band are likely to cause less problems than lots of distortion in a few places, yet quoted measurements will often represent an average figure...
How do you measure transparency?
Transparency equals measured accuracy + low inband distortion + time/phase accuracy + coherent dispersion. All of that is measureable. They almost need to have a "tranparency index" that weighs and combines these factors, except that there'd be no industry wide agreement on how to do that.
Quote from: skrivisMetal diaphragms _will_ exhibit breakup, since we're not dealing with perfectly stiff materials. When they do, there isn't any internal damping to control the resonance.It doesn't matter if it's not audible. You say it is, but have you ever just considered that you like a lossy, softer version of reality?
The O'Toole/NRC-related designers don't seem to adhere to those criteria in that they don't seem to worry about time/phase accuracy.
Low inband distortion doesn't always tell the whole story either. Out of band distortion can be a problem too. Low overall distortion is a nice ideal, but there may be other things that are more important. The way distortion is measured may also mask some nasty behaviors...
A big speaker system with a ton of drivers for each frequency range may have vanishingly low measured distortion, but utterly incapable of properly passing a transient.
A system could show excellent distortion figures from 20Hz-20KHz, and frighten away bats and small pets because the tweeter puts out lots of trash above 20KHz.
My "lossy, softer version of reality" if it actually is so, matches very well with what I hear in the studio.
If your amplifier oscillates at 30KHz, you won't hear it, but your tweeter will, and it will likely burn out. That's perhaps a worst case of the audibility of hi freq trash. Sure, and if your car runs out of oil, the engine will fail. That same amp would blow a soft dome too. SACD has an *enormous* amount of high frequency "trash" and yet audiophiles love the sound, saying it's more "analog" and they want more extended tweeters so they can "hear" all the nasty effects of the noise shaping. God bless their little audiophile hearts! QuoteI really suggest that you look into what effects signal above the audible range has. Otherwise you're just kind of burying your head in the sand and ignoring it. Not really. If a tweeter sounds better to me, it's better for me. I can listen to the NHT's relatively cheap metal tweeter all day and yet some expensive metal and soft dome tweeters annoy me. Certainly cheap soft domes annoy me. No detal *and* a lot of distortion. It's the quality of the tweeter and the implementation that counts. The hiqophons might sound great, but if they can do cymbals well, they'd be the first soft dome I've heard that can. QuoteAs for the whole stiff vs. less stiff thing, my contention all along is that some materials are "stiff enough" to get the job done while having good internal damping so that when they do get into trouble it isn't the end of the world. I understand that, but what you seemed to saying is that metal has an issue with resonances at the center of the dome and all I was pointing out is that soft domes are, by nature, far more problematic so you can't really use this as a negative for metal. QuoteThe figures that I've seen show that metal diaphragms with damping applied mass more than composite materials where the damping is part of the structure. I'm thinking mainly of doped silk domes and paper or wood pulp cones. The added mass will reduce resolution. (I'm sure it isn't always the case that metal plus damping weighs more, but it's something I'm going to look at more closely.) Mass doesn't reduce resolution so much as frequency response. The future lies in either stuff like diamond, beryllium or very fine vapor deposited laminated structures where multiple layers equal the thickness of a single metal dome, but are more rigid with the resonance far higher in the frequency range. If you really dampen a soft dome, you're going to make it too heavy and it may not resonate, but it will roll off. QuoteI think I can also say that we're not necessarily talking about night and day differences here. There's room for both viewpoints. I'm also quite willing to listen to the Xd's and admit I'm wrong if they do as well as you say. It's one of the things on my to-do list, and I would have already listened to them if there were a local dealer. Agreed. I like the sound of many soft domes, but prefer what I believe to be the added realism of a good metal dome. I don't discount that there are soft domes more to my taste, but most of the speaker brands I like happen to use metal. I am picking up Triad, so I'll get to hear some nice ScanSpeaks though. I just find that there is a lot of distrust, almost anger towards metal domes. It's like women, you can have a bunch of bad experiences, but if you take that baggage forward, you'll end up missing out (when a nice metal-equipped speaker crosses your path). QuoteGetting back more on topic, I do feel that the Ellis Audio 1801's are a good design. I may not totally agree with David, but I do feel his design has merit. My preference for his style of doing business means that I would be more comfortable with a product from him than with one from a much larger company. Sure it's a good design, basically. The only thing is, for you, the W18 has a big 4kHz spike, something like 15-20dB as I recall, which I'm sure is notched rather than entirely avoided. You will get some of that in the sound, it's unavoidable, but the resolution below that will be fantastic. It will likely have a big of a brightness to it, possibly even a little more fatiguing than if it were poly or paper. But that's the usual price for low midrange distortion. I remember hearing the Veldyne 661s "the lowest distortion speaker in the world" and I couldn't listen to a full song, not even a light jazz song (I'm sure Tool would have sent them into overload) without leaving. But with the right notch and a relatively low and steep crossover, I'm sure it would be fine. NHT feels that the SEAS cones are unusable in passive analog situations. I'm not sure I agree with it, but I understand why they'd say it. The use a 110dB/octave at 2000 Hz to avoid ringing. With a 24dB/octave crossover, it would have to be down below 1000Hz, even more like 500Hz, which is why a notch filter must be in there. Of course, NHT doesn't like using high parts count crossovers either, so it's more of a difference of design theory, which is fine. I would be a little surprised, though, to see you not liking metal domes because they have a 20kHz+ spike, but then being okay with a metal midrange that has a 4kHz spike. There is a paper or poly version of that driver, I believe, that would almost drop in, but without the notch filter. You'd lose some resolution, but possibly get more of the sound you like.
I really suggest that you look into what effects signal above the audible range has. Otherwise you're just kind of burying your head in the sand and ignoring it.
As for the whole stiff vs. less stiff thing, my contention all along is that some materials are "stiff enough" to get the job done while having good internal damping so that when they do get into trouble it isn't the end of the world.
The figures that I've seen show that metal diaphragms with damping applied mass more than composite materials where the damping is part of the structure. I'm thinking mainly of doped silk domes and paper or wood pulp cones. The added mass will reduce resolution. (I'm sure it isn't always the case that metal plus damping weighs more, but it's something I'm going to look at more closely.)
I think I can also say that we're not necessarily talking about night and day differences here. There's room for both viewpoints. I'm also quite willing to listen to the Xd's and admit I'm wrong if they do as well as you say. It's one of the things on my to-do list, and I would have already listened to them if there were a local dealer.
Getting back more on topic, I do feel that the Ellis Audio 1801's are a good design. I may not totally agree with David, but I do feel his design has merit. My preference for his style of doing business means that I would be more comfortable with a product from him than with one from a much larger company.
Quote from: skrivisThe O'Toole/NRC-related designers don't seem to adhere to those criteria in that they don't seem to worry about time/phase accuracy.Of course not, because it's the hardest to achieve and has the least amount of gain when you do. And it has the worst side effects - higher distortion, more lobing, more complex crossover, limited driver choices, etc, etc, etc. We're far more senstive to the latter problems than time/phase, that really needs to be the last thing to be done and digital makes it possible without nasty side effects.
Sure it's a good design, basically. The only thing is, for you, the W18 has a big 4kHz spike, something like 15-20dB as I recall, which I'm sure is notched rather than entirely avoided. You will get some of that in the sound, it's unavoidable, but the resolution below that will be fantastic. It will likely have a big of a brightness to it, possibly even a little more fatiguing than if it were poly or paper. But that's the usual price for low midrange distortion. I remember hearing the Veldyne 661s "the ...
Lobing is only an issue if the user doesn't know about it or doesn't know where the lobes are. There's a definite sweet spot with most speakers and that's where I sit to listen.
There is some talk about power response being supremely important because it determines what the room-reflected sound will be like and that sound is a major component of what you hear. I'm not so sure that you need to base your design on a desire for flat frequency and power response. It seems like the wrong way to start in my opinion.
More complex crossover? Not always. My current speakers have 1 cap, one coil, and 2 resistors in each crossover.
More limited choice of drivers? Yep. Why is that bad? Good drivers are available, so you use those.
I tend to feel that time/phase accuracy needs to be the first thing, rather than the last. As Pat McGinty says," Our speakers are designed in the time domain FIRST and, as it turns out, when a speaker's timing is correct, the frequency domain just plain lays down and falls into place."
There are a number of things about NHT's design that I like, but there are a few areas where I'm skeptical. The proof is in the pudding, so that will have to wait for an audition of them. Other people have voiced similar concerns, about the Xd's and the technology they use, so I'm not alone.
Also, you have to admit that David's cabinets are far prettier than the Xd's.
I'll give you that they're more "traditionally" pretty However, I happen to think Xd is gorgeous in a more Italian "Ducati" way. I'm not totally thrilled with the color combo, but I think the styling is tremendous and at least differentiated. I guess it depends on the trappings of your home and your taste.
DEQX or a similar system offers a number of advantages, if it's done correctly. However, it's more complex and more expensive. There could be a tendency to skimp on drivers and "correct" them so the end result measures well and the final price of the system is acceptable.
Multi-amping, which is a requirement of DEQX, can also have advantages. But it does require multiple channels of amplification, and there again there could be a tendency to skimp on each channel.
There is also a school of thought that says that 1st-order series crossovers produce a beneficial interaction between drivers.