Fernando
As an engineer you should certainly understand that because many people have done something the same way for a long time does not mean that today it is the optimum way to do things. They might have taken the easy road, or were dealing with limited capability components, there are many reasons why an engineers designs may not have been optimal. New technologies and new components allow for new and different approaches that can far exceed the capabilities of "the way its always been done."
I personally think that a crossover at 3 kHz is not a very good idea, and there are technologies today that allow for that crossover point to be lowered substantially. I don't see the need to explain why a lower crossover point is preferred as that is fundamental to loudspeaker design and most will understand why it is true.
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People often find that they like imperfection. They like the sound of their system despite a weakness in the engineering domain. What happens is they come here to the forum for some company and feel belittled whether the posters intend it or not. There are many people who won't post here, they will only read, because of the challenges of interacting. I don't view or treat this forum as an engineering board, it's a social environment. There's room for the wonks and the artists.
Many of the products and people mentioned are actually current designs using current drivers. This includes the Sony, B&W and Aerial Acoustics examples which use versions of some of our favorite drivers on these boards. My own experience tells me I prefer the sound of higher crossovers and the small compromise in directivity is no deal breaker.
I am sure the engineers at Bowers and Wilkins have the technology at their disposal to take a tweeter to 1.5 KHz. They simply choose not to do so, preferring to cross their 6" hi tech drivers at 4 KHz. It seems they are using today's technology to design drivers with break-up modes above 3 KHz instead. Given their results, which one of us can tell them they are wrong? Also my apologies to Andrew Jones for not including him among the fools who today use 3 KHz crossovers. I meant no disrespect.
Bigun - what you say is probably true, but I often times have trouble patronizing misconceptions that people have. It's not a good idea to knowing let people go on believing in things that are know to be false. There are always issues where we don't know the right answer or there is no right answer, but many times there is a factual answer and IMO that should be expressed.
As an engineer I'll leave the objective data to tell the true story. As Toole and Olive show good objective data is the best correlate to global perception.
As engineers we can only try to model the real world as we perceive it. The "objective" data is in reference to that model. The faithfulness of that model to reality is only as good as the subjective assumptions it was based on, including the importance we give to the various parameters that make up the model.
Yes, by any objective measure, increasing the upper frequency to a driver compromises directivity. There is no question about that. But that is not the question. The question is in the best model we can conceive of how we hear a musical performance, how much does directivity matter in relation to other parameters that are in conflict with it. The answer to that question is not in black and white.
A relative of mine once explained the difference between an engineer and a management consultant and his story goes counter to public perception. The management consultant would give an answer as 82.75 while the engineer would say between 80 and 85 to the exasperation of the management board. The difference was that the engineer understood the uncertainty of his calculation while the management consultant did not.
Yes, by any objective measure, increasing the upper frequency to a driver compromises directivity. There is no question about that. But that is not the question. The question is in the best model we can conceive of how we hear a musical performance, how much does directivity matter in relation to other parameters that are in conflict with it. The answer to that question is not in black and white.
A relative of mine once explained the difference between an engineer and a management consultant and his story goes counter to public perception. The management consultant would give an answer as 82.75 while the engineer would say between 80 and 85 to the exasperation of the management board. The difference was that the engineer understood the uncertainty of his calculation while the management consultant did not.
Nothing is ever black or white, but I don't think that the situation is as gray as you are implying (or that I perceive you as saying.) Toole and Olive have spent two lifetimes on exactly the model that you are questioning. If you are not familiar with their results, then you should be if you want to continue in this discussion. They are quite convinced that a constant (flat) DI with a subtle HF power response roll-off is necessary for the best possible reproduction. I concur with that conclusion and all my statements here are based on the validity of their results. I may differ with them on what the actual value of the DI should be, but not on whether it should be flat/smooth to the lowest practicable frequency.
The speakers that you have mentioned all seem to me to be designed with a size limitation in mind. This would tend to push the crossover frequency higher. I have found that small is a virtual requirement in the EU, but almost the exact opposite is true here in NA. We have larger rooms and unattached homes which lend themselves to larger sizes with ever more power output (required), which is not feasible in the EU for obvious reasons.
Hence, for a system constrained in size I can see that higher crossovers may be the optimum solution given those design constraints. But that is not going to be true for a system without such constraints. In NA if a user wants "small" they tend to buy Bose.
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I am familiar with their work. I also have the bad habit of questioning conclusions regardless of where they come from, when I see evidence to the contrary. I do not disregard Dr. Toole and Dr. Olive's work. It has been a great contribution to the knowledge base. However, I have seen products designed and built by very competent people, and that have achieved reference status in the industry, that have made some compromises regarding those principles. When I see that I usually ask myself what else don't we know.
If you insist I have to follow a particular bible or religion to continue a discussion, then perhaps I should not continue. I am beginning to remember why I left these types of boards some years ago.
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If you have spent a considerable part of your time, investing it into your passion, you will gain a lot of experience. That experience is very helpful but it does condition all thinking that follows it. Questioning 'conventional' wisdom, or whatever it should be called, it essential for progress. Science has an interesting history of such traps and the escapes from them. Keep questioning.
In which loudspeakers did he use 3000Hz crossover ?
I don't know of any and i'm really interested to see.
Well, to Andrews defence (unlike other fools) he did not do that in Pioneer TAD series that presents his reference to achieve a sound feature but in budget HT loudspeaker set. I listened his interview about that particular Pioneer speakers where he explains that he made the best possible for a given budget. For a goal price of 550 bucks retail for complete 5.1 system a guy needs to make some compromise. You can't get a decent tweeter for couple of bucks that has low Fs (just a wild guess) so he used 4" and 5" drivers that can work good enough up to 3KHz so they can take the load of the tweeter to avoid failure due to system misuse.
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That's quite funny as Gedlee is probably the least inclined to follow "religious belief" in loudspeakers. He has documented his work....
With that said, you have your perception of "good enough" other people maybe can't live with that
Peter
I never said that you had to follow it, only that you had to be aware of it.
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