Well, we've been talking about various tweeters, in particular, inexpensive ones. I like hearing people's opinions, especially seasoned designers. The response was what I expected from someone with vested commercial interest, however it was in the spirit of conversation, not confrontation.
My comments are meant this way too. Simply as an explanation for the use of normal tweeters as I see it.
Next to impossible to use in a passive system ? I better take my ribbon tweeters and their passive network and throw them in the bin then.
Yes its correct that a true constant directivity (in both vertical and horizontal axis) waveguide requires equalisation to give a progressive boost to higher frequencies to achieve a flat on axis response, but that can also be done passively by attenuating the lower end, which I presume Earl's networks do.
Not all wave-guides are pure constant directivity and require such equalisation though. In particular ribbon wave guides due to the long narrow ribbon tend to only be (approximately) constant directivity in the horizontal plane, where it is IMHO most important. In the vertical plane there is a smoothly increasing directivity as frequency goes up which keeps the on axis response more or less flat without external equalisation. (In fact most ribbons tend to be a little hot right at the top end and need a little bit of shelving off rather than boost)
So to say that all wave guides are impractical in a passive design is misleading at best, bordering on flat wrong at worst. Many types of wave-guides are just as easy to use in a passive network as a conventional tweeter.
That comment doesn't make sense in the context of the complaint levelled at a CD wave-guide requiring equalisation. If the equalisation of the wave-guide is done passively that means throwing away some efficiency at the low end of the wave-guides operating range in the network, not boosting the high frequency end.
This makes it easier to match with the sensitivity of the woofer, not more difficult. Earl could have easily chosen a bass alignment with a lower cut-off frequency and lower efficiency and padded the wave-guide tweeter down a few dB to match. Overall system sensitivity would have been a bit lower but the dynamic performance and all the other benefits of the wave-guide would have been just the same.
However I'm guessing he chose not to do so because he's on record as preferring to use multiple dispersed external subs for low bass response, and therefore probably made the decision to choose a bass alignment with a higher cut-off frequency that would most accurately match the wave-guide's "corrected" sensitivity.
The fact that it's a wave-guide is nothing to do with the choice of bass efficiency - any conventional driver with the same overall sensitivity as the post-equalisation wave-guide would have presented the same design trade-offs and options.
Again, passive or active has nothing to do with it, nor does the use of a wave-guide dictate that there must be a high cut-off frequency high efficiency bass alignement - that is purely Earl's design choice.
Large waveguide designs like Earl's are something of a challenge to get right thats fair to say, but smaller waveguide tweeters of a similar faceplate size to a dome tweeter are perfectly usable and easy to design around, in fact in some ways I think they make the design a lot easier - for example greatly reduced baffle diffraction effects.
Yes I find that amusing too. Anyone that has read Earl for long enough knows that he has settled on large format 2 way wave-guide based systems as the "optimal" approach, and discussion of any alternative approaches is anathema to him
His mind is made up.
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Yes I find that amusing too. Anyone that has read Earl for long enough knows that he has settled on large format 2 way wave-guide based systems as the "optimal" approach, and discussion of any alternative approaches is anathema to him
I understand that his mind is "made up" however having availed himself to the conversation at hand, I thought I'd drop the question anyway, in good fun, knowing full well that the response was going to be chilly.
It seems that nobody appreciated the subtext.
Be warned though, if Danley shows up, I might ask him the same question.
"As correctly stated in some previous posts, CD is not really achieveable at LFs, but then its also not really necessary, "
I don't know how you reached that conclusion, I certainly don't agree with it. But that is besides the point. Even if your system was a pulsating sphere that was flat across the entire audio spectrum it would not meet the criteria I set forth. You speaker like everyone elses results in early reflections that have a different spectral transfer function than the incident wave. Your speaker has no way to compensate for this. Therefore the overall spectral transfer of energy from the speaker to the listener will never be flat and will never be the same in any two rooms nor the same in different positions in the same room.
And that is only one part of flat response, The other is dealing with the variables of the program material itself. The recording and playback components must be viewed as a single system. At the current state of the art there is no way to compensate for that variable except to equalize each recording individually on playback, sometimes each track individually. It takes a trained ear and a lot of patience.
When both these criteria are met, it is possible to reproduce the timbre of musical instruments from recordings as those instruments would be heard in your listening room. The reproduction or recreation of the acoustic effects of large performance venues which affects well over 90% of what you hear at a live performance is orders of magnitude more difficult to achieve and far beyond the current state of the art, all of the current "surround" systems considered.
I would have thought that a flat responding puslating sphere would have met your requirement. It would clearly be flat on every axis and equall energy on every axis (omnidirectional). If that is what you feel an ideal speaker is (I asked and you never answered) I would again ask what studies support that view? Paper after paper in the last 30 years have concluded that flat power response and omnidirectional response are not only not required but are not desirable.
Let me again point out that flat reflections added to flat direct response do not give a flat combined response. Direct sound and an added reflection will result in a comb filtered response that will always be far from flat. The combined response is more dependent on delay than reflections spectrum. So why would flat room reflections be essential?
This, of course, also ignores the ears ability to latch onto the direct sound, which further diminishes the requirements of any particular late sound balance.
If you disagree, cite some references that support your point of view.
David S.
Earl, if your speakers have same FR independent of direction within their cutoff angle, why is it necessary to position them so that you are listening off axis? I saw Zilch's measurements and they didn't seem to be independent of angle to me. It seemed to me that the output of the highest octave was as dependent on angle as most other speakers are. Even the wide dispersion AR 3/4" tweeter was down 5 db 60 degrees off axis at 15 khz. that's a whopping 70% loss of energy. Most tweeters are much worse, down at least 10 and more commonly 15 db at 45 degrees off axis at 15 khz with respect to their on axis response. This can be seen from their published data.
I found what I think is an interesting quirk in the tweeter used in Snell AII and a comparable one in AIIIi. I duplicated the sound I found peculiar to them through experimentation with arrays. This one particular array produced excessive lateral early reflections in the range of around 7 to 8 khz with respect to their aggregate's on axis response. When I increased the crossover cutoff frequency to the lateral components of the array, that peculiar coloration disappeared. I'd asked Peter Snell's mother at a trade show in 1987 shortly after his untimely death and around the time of introduction of the AIIIi why a piece of polyurethane was glued to the front of the tweeter. She told me it was to increase dispersion. I found this interesting, increasing dispersion laterally by restricting output frontally. When I duplicated this quirky sound which I actully liked, I listened to it for several hours and then eliminated it. It has never interested me again and I know I could duplicate it whenever I want to. I no longer had any desire to own a sample of that speaker.
I found what I think is an interesting quirk in the tweeter used in Snell AII and a comparable one in AIIIi. I duplicated the sound I found peculiar to them through experimentation with arrays. This one particular array produced excessive lateral early reflections in the range of around 7 to 8 khz with respect to their aggregate's on axis response. When I increased the crossover cutoff frequency to the lateral components of the array, that peculiar coloration disappeared. I'd asked Peter Snell's mother at a trade show in 1987 shortly after his untimely death and around the time of introduction of the AIIIi why a piece of polyurethane was glued to the front of the tweeter. She told me it was to increase dispersion. I found this interesting, increasing dispersion laterally by restricting output frontally. When I duplicated this quirky sound which I actully liked, I listened to it for several hours and then eliminated it. It has never interested me again and I know I could duplicate it whenever I want to. I no longer had any desire to own a sample of that speaker.
I understand small waveguides are perfectly useable in normal systems, with desirable characteristics, lots of manufacturers use them.
Since most music has the lions share of its energy below 3khz then only the largest waveguides will have a truly significant effect. As far as I can see this means very low crossover and very large waveguides. I am not knocking small waveguides but I can see why Dr Geddes uses such large guides. It may be easy to produce smaller waveguides and produce nicer measurements but their real world effectiveness or relevance seems significantly diminished.
Dr Geddes love of large waveguides, high sensitivity and power handling seems to be linked to a love of massive sound pressure levels. I think all DIY builders reading his comments here should be aware of the context.
I have little doubt that a Gedlee Home Theatre system would be awesome.
DBMandrake said: " Earl could have easily chosen a bass alignment with a lower cut-off frequency and lower efficiency and padded the wave-guide tweeter down a few dB to match. Overall system sensitivity would have been a bit lower but the dynamic performance and all the other benefits of the wave-guide would have been just the same."
This is what I would have thought. I wonder just how much efficiency would have to be thrown away to achieve this?
Perhaps this would not go down well with the horn/large waveguide market. I think it would make the speakers more saleable (even if they were not technically superior), although as a small manufacturer I imagine Dr Geddes has his work cut out already.
I would have liked to see a reply from the good Doctor on this though.
If large Waveguides like this are so inherently good why not see more full range passive speakers like this from Gedlee or a larger manufacturing partner?
Since most music has the lions share of its energy below 3khz then only the largest waveguides will have a truly significant effect. As far as I can see this means very low crossover and very large waveguides. I am not knocking small waveguides but I can see why Dr Geddes uses such large guides. It may be easy to produce smaller waveguides and produce nicer measurements but their real world effectiveness or relevance seems significantly diminished.
Dr Geddes love of large waveguides, high sensitivity and power handling seems to be linked to a love of massive sound pressure levels. I think all DIY builders reading his comments here should be aware of the context.
I have little doubt that a Gedlee Home Theatre system would be awesome.
DBMandrake said: " Earl could have easily chosen a bass alignment with a lower cut-off frequency and lower efficiency and padded the wave-guide tweeter down a few dB to match. Overall system sensitivity would have been a bit lower but the dynamic performance and all the other benefits of the wave-guide would have been just the same."
This is what I would have thought. I wonder just how much efficiency would have to be thrown away to achieve this?
Perhaps this would not go down well with the horn/large waveguide market. I think it would make the speakers more saleable (even if they were not technically superior), although as a small manufacturer I imagine Dr Geddes has his work cut out already.
I would have liked to see a reply from the good Doctor on this though.
If large Waveguides like this are so inherently good why not see more full range passive speakers like this from Gedlee or a larger manufacturing partner?
Oh? Do you see it as an insult then? The woofer + horn is tried and true because it works well. It's been around since what, the 30s? Not all of them sound good, of course, but many do - like yours. I fail to see what is not classic about the design, other than the foam. That's new.
There are a plenty of powered pro designs on the market ever since JBL sold millions of Eons. (not great sounding). Mackie, JBL, EV, EAW, Yamaha, Behringer, Meyer, etc.
Are you implying that if you stick a piece of foam in the horn of a Disco/PA Speaker you get an advanced 21st century controlled directivity monitor?
The original purpose of a CD loudspeaker system using a horn as I understand it is to enable sound reinforcement systems for large public spaces like sports arenas to get the most uniform coverage with the fewest speakers and maximize gain before feedback. It is so well developed a science that the actual design can be performed with computer software alone which takes into account everything including the speaker cutoff angle.
The application of this concept to high fidelity home sound reproduction is I think a rather recent development and may be practically unique to Gedlee, I'm not sure but I know he is one of its most ardent proponents. I've never heard it myself so I have no real reference to judge it by. I don't know of anywhere in my area where I could hear one and I have no intention of spending money to borrow a pair to find out for myself. I live very far from Michigan and I have no intention of going there. My house is already flooded with speakers. I seem to accumulate them faster than I listen to them and I'm not sure I know how or why this keeps happening. My goal is to make them all sound exactly alike regardless of what room they're in.
I have to ask, are comments meaningful only when they favor your speakers? You post all the time about science and measurement being far more important......accept a few times when you post "comments" about your speakers hold some sort of weight.
At this time in all my research there are zero controlled listening tests validating your speakers. Should we not hold your speakers to the same litmus test that ever other subjective claim gets?
FWIW, Im definitely a person that agrees with the design principles but I think there are other designs that work very well and your designs are not alone. I also believe that Dome designs are complete suck *** sounding piece of crap type designs only useful for specific applications, none of which are meaningful to me.
Back to the thread, I think most DIYers think cheap domes sound great because they can not rub more then two coins together to get higher end products in the first place
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I have to ask, are comments meaningful only when they favor your speakers? You post all the time about science and measurement being far more important......accept a few times when you post "comments" about your speakers hold some sort of weight.
At this time in all my research there are zero controlled listening tests validating your speakers. Should we not hold your speakers to the same litmus test that ever other subjective claim gets?
FWIW, Im definitely a person that agrees with the design principles but I think there are other designs that work very well and your designs are not alone. I also believe that Dome designs are complete suck *** sounding piece of crap type designs only useful for specific applications, none of which are meaningful to me.
What litmus test would that be?
Nah, don't think so:
An externally hosted image should be here but it was not working when we last tested it.
Anyone that actually understands how to desgin a proper audio system will relize that there is no sacrifice in bass when subwoofer systems are actually required.
Also, Geddes Summas run as LARGE main speakers and people SHOULD add properly placed subwoofers around the room.
The true problem is any audiophile that thinks main speakers are remotely good at handling any in room bass response alone.
Conclusion......who cares what a main speaker has in terms of bass response below something like 60Hz. If someone wants proper bass they should add the proper subwoofer system, anything else is just a compromise.
Real scientific measurements and Controlled listening tests.
The point is that Geddes posts all the time that science and measurements matter a great deal (I do agree that they matter 100% over subjective uncontrolled opinion). Even in this thread he has posted how much they matter.
The only time they never matter to him is when he needs to post subjective comments about his speakers.
Subjectivity is absolutely meaningless. What is needed is controlled listening tests. Only then can any conclusion about his speakers vs other high end controlled directivity speakers exist.
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Tell that to my A5s, Doug.
The proof is in the data , not some subjective conclusion
There isn't a main speaker that competes with the performance of a properly design subwoofer system. The room dominates everything under 300Hz and our only chance is to control that problem properly.
2.0 = compromise (costs to much, no room...blah, blah, blah), misunderstood, bad logic....old guy stubborness to me, Im not interested in excuses
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