It would be more correct to say "throwing around naive notions of pure waves in pure air playing pure tones from pure drivers on pure sources (with none of those pesky crossovers in the way)."
But once you think about acoustics more comprehensively and with some minimum attention to humans in the loop, the picture changes.
Speculation.. that sounds like an exaggeration. Telling you that without telling you how, is not showing the attention to detail that would make or break such a procedure. Did the tech say anything else?
If you are using one of the big Heil AMT drivers, the vertical dispersion is very limited, to they are less susceptible to diffraction (because of the drivers height).
Johan-Kr
Johan-Kr
No Johan. I am not wild about the big Heils AMTs. But I absolutely love the smaller, round AMTs they made.
Not speculation at all. The person you speak to is the owner as well, unless I'm mistaken. Regardless, he has been there since the 70s. He knows everything ! He has been telling people this for many years.
He told me he was not going to offer any ways of doing this mod. Only that it is a BIG improvement.
He explained it was as simple as physically aligning the tweeter face and woofer cone dust cap.
He explained it was as simple as physically aligning the tweeter face and woofer cone dust cap.
- Does this next fact change anything? Measuring the distance from woofer to tweeter gives me 2.5". That is a large distance. Considering that, the angle of the ramp back would be slow and slight. Maybe not so rough on baffle diffraction issues?
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As others have already pointed out, what you care about is phase alignment through the crossover region so that you get flat frequency response over a decent vertical listening window. If you are doing this to get the 10kHz signal from the tweeter to happen at the same time as the 500Hz signal from the midrange, you are wasting your time. If this was audible, the JAES would be filled with people who had tested it and written a peer reviewed paper on its audibility.
Tilting the speaker back creates problems because it sprays sound at the ceiling from both drivers. If the tilt angle is small, then this affect won't matter much, but then again if the tilt angle is small, then the offset is small, so what is the point? Just design your crossover to have the correct phase shift at the crossover frequency. This requires some measuring equipment, which is virtually free now. If you are building a speaker system by ear, you are honestly wasting your time.
No amount of magic foam on the baffle is going to stop the reflection from a 2" step only 4" from the tweeter. If you cross the tweeter over at 6-8kHz with a steep filter, this could work, but not with any normal crossover frequency (2-3kHz).
Tilting the speaker back creates problems because it sprays sound at the ceiling from both drivers. If the tilt angle is small, then this affect won't matter much, but then again if the tilt angle is small, then the offset is small, so what is the point? Just design your crossover to have the correct phase shift at the crossover frequency. This requires some measuring equipment, which is virtually free now. If you are building a speaker system by ear, you are honestly wasting your time.
No amount of magic foam on the baffle is going to stop the reflection from a 2" step only 4" from the tweeter. If you cross the tweeter over at 6-8kHz with a steep filter, this could work, but not with any normal crossover frequency (2-3kHz).
In the bigger picture of a cross, putting drivers near each other brings a few standard compromises such as on listening axis alignment, baffle configuration, and a number of potential off-axis irregularities.
I like to assume that a person will recognise and deal with basic issues like inter-driver phase as the need arises. Sometimes however a person unwittingly leaves it to chance, and claims an improvement on whatever else they were doing at the same time. Really, is more or less than half the information out there correct? You might see how what they write flows and shows what they know, and ask further questions.
(Seriously though, it may have been a big improvement but it still isn't known (for certain) why? Maybe if you do the wrong thing, the right way it will be worse, not better?)
I like to assume that a person will recognise and deal with basic issues like inter-driver phase as the need arises. Sometimes however a person unwittingly leaves it to chance, and claims an improvement on whatever else they were doing at the same time. Really, is more or less than half the information out there correct? You might see how what they write flows and shows what they know, and ask further questions.
I've heard that before. Are you sure you weren't talking to the personnel officer?
(Seriously though, it may have been a big improvement but it still isn't known (for certain) why? Maybe if you do the wrong thing, the right way it will be worse, not better?)
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