@ Dave Rickard: GOOD measurement a.k.a. useful measurements will show that, I'm sure about that. A simple frequency response plot won't show it. A such measurement can only show energy and nothing about the time domain integrity.
The problem about the trickery is that the original signal is not played back as supposed. The ear might not as easily be fooled with room reflections of the tops output for example. You could compare it with me-too-products in the snack industry (you know, they look a it like the original brand stuff, taste a bit like the original...): It's simply not the real deal.
@ peter.golde:
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and the path doesn't allow distortion created by the driver to be heard
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And that is why? Simple, because the path and its folds/bends create a lowpass filtering out distortions above the usable range (as well as signal!). I didn't calculate this to the finest details but I think that BF puts in speakers with a 'natural' output increase towards higher frequencies, so it almost equals out frequency response-wise. That won't help on the time domain....
It has nothing to do with comparison. Most things the professional manufacturers throw at the market has at least the 'potential' to work like intended (sometimes it actually does, sometimes the drivers don't do what they should, sometimes the crossover is bad... but the enclosure itself could do it). And that is what's basically missing with the DRs. If I see for example a straight horn with a 10" or a 12", see that the throat and mouth are of appropriate size, there is no reason for me to believe that this horn won't play quite good up to 800 or 1000Hz (without phaseplug). If I see bass horn folded two or three times with a path length >2m I know it won't play nice above ~100Hz. In other words I, like every designer who did his homework, can tell by the enclosure design if the physical properties of the enclosure actually allow what the designer intended. That's not arrogant or ignorant, it's simply the basic knowledge a speaker designers should have about physics. And noone can do 'magic' beyond physics. You can argue and discuss with ME, but not with physics.
So if I had to decide for a manufactured or a DIY speaker, I would never go for the DRs in their original form. I think most professionally manufactured speakers (from a real brand, not chinese cheapo cabs or lowest MI grade stuff) are a much better choice than the BF designs. But you are right that I would buy or build most of them either for myself. OTOH I have no problems to recommend a design which would work for some requested applications even if I wouldn't build them myself. The DRs in their original design are simply a no-go for me.
With a tightly packed piezo crossfire array you will barely hear lobes/combfiltering, because the distance between the drivers is too small. This doesn't change the fact that these lobes/combfiltering issues are present. They always are if you use multiple drivers in a freq range >> lambda half of the drivers distance to each other (unless you can make them stop overlapping in coverage). Physics again.
But with bigger horns the distance from center to center is bigger, so combfiltering will be an issue. Of course if the HF drivers are on top of each other you won't notice anything in the horizontal plane, so you'd have to move to the top and away from it to get it.
Antone Atmarama Bajor wrote on Sat, 18 November 2006 00:24 |
I think Jens is concerned that there maybe time domain smearing due to the reflection/diffraction of the upper range of the mid bass horn.
I think he is concerned about the wavelength to bend relationship at the high cut of the horn.
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That's definitely part of the problem.
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Though there is smearing introduced in any HF horn at the High end of its response due to Radical Diffraction slots (in attempt to improve coverage)
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That's why I like HF horns without or with 'a little bit of' diffraction slot. I know they tend to beam on HF, but that's in most cases not as bad as it sounds...
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In my thoughts Its midband smearing is probably about as bad as most of the compression driver horn hi end smearing. But I could be wrong.
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It's worse, because there is less precision in building them and there is no sound at all going straight through the horn. Every bit of sound has to be 'bent around the corner'.