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soft dome versus hard dome tweeters

As my internet window shopping continues, I was reading on some speakers that listed for the tweeter textile dome and also silk dome.

So then I used the 'search discussion' function on this site on the subject of soft versus hard dome tweeters and it seemed as if most of the members who offered opinions used that "harsh" and "fatiguing" and "ringing" to describe how they felt about hard dome speakers. In the admittedly short time that I spent reading, I was not picking up a lot of love for hard dome tweeters.

But there are reputable speaker manufacturers that seem to have gone the extra mile to make their hard dome tweeters as hard as possible using, for example, beryllium or artificial(?) diamond dust.

I wouldn't expect a consensus on much of anything audio, but did I just by luck to find responses by mostly people who prefer soft dome tweeters?  Because if they really sound that bad (harsh/fatiguing/ringing) in comparison, why would reputable manufacturers choose this route?  And I do realize that appreciation of a sonic effect is subjective, so did I just happen on responses by members who had mostly the same subjective perception?

immatthewj

Showing 2 responses by asctim

asctim
505 posts
 

@erik_squires 

 

I'm all about that midrange too. But a lot of tweeters go a significant way down in to it. And, how that midrange marries to the other frequencies matters. So, what's the best approach to a coherent, uncolored, beautiful midrange?

It would make sense to have no crossover in that range. According the chart I'm looking at, that would ideally go from about 250 Hz to 4000 Hz. What kind of a driver could cover that range with a good dispersion pattern? I'm thinking a fairly large horn, maybe 90 degree flare, and a not too big driver. Center to center on the tweeter is going to be a problem, but it might be worth it. I don't know.

I'm currently running 600Hz on up on a CD  horn and it does some magical things.  But I suspect it'd be better if I could get it down to 250 Hz on the same horn.

Maybe the multi entry horns are the answer. It just bothers me that they require holes be drilled in a horn flare that is meticulously intended not to create diffraction events inside. I know guys are working hard to optimize those designs because they feel that point source coherency is worth a little trade-off in diffraction events.

asctim
505 posts
 

@erik_squires 

Thanks for the WAWB reference. I looked that up on DIYaudio. One guy talks about the excellent balance and sharp percussion. This is what I'm noticing on my system lately. With  my CD horn it wasn't really doing those things to full capacity until I recently just EQ'd the heck out of it using an FIR filter. The raw response droops considerably at both ends, but I was afraid to "overdo" the EQ. Now it's flat as a board all the way down to the 600Hz LR 48 dB crossover point, and it follows the crossover target with near perfection. And, the phase is flat all the way through. That much EQ required as much as -15 dB from the peak at around 2 kHz. It seemed too extreme to me, but it was the right thing to do. 

Speaking to the beaming on top with the WAWB, I've been toying with a Dayton aluminum dome midrange, which has a breakup peak at about 12 kHz. That thing beams on top too, and I think I understand why hard domes beam like that. The middle of the dome is just too loud compared to the edges, and the middle part of the dome is relatively flat. The sound off the dome at all points radiates perpendicular to the surface to make spherical waves, but with the center being too loud, the pattern doesn't look nearly as good as one would hope. I think one solution might be to somehow reduce the efficiency of the dome at the center. A way to do that might be to make it leaky in the middle by drilling holes. This will reduce the overall efficiency as well, but it might be worth it if it improves the dispersion. The 2" dome could be putting out something up to over 16 kHz with half way decent dispersion if the hole drilling works. And of course the resonance would need to be notched down.

I bought an old Dremel drill press from my neighbor. I'm ready to drill, but wondering if it's worth it. It might do something really bad and render the driver useless. If it works as well as I'd hope, it'll reach down to 600Hz without horn loading. Maybe 400Hz with horn loading. That's just a little lower than I'm already getting with my JBL 2426H on its horn.

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