I've built several loudspeakers over the years, and many of them have used first-order crossovers. There are some distinct advantages for home use, not the least of which is cost. They generally sound pretty good too, when you don't have banks and banks of loudspeakers to try to keep phased.

But I always seem to poof the tweeters. I mean, over about 10 or 20 watts, the tweeters just eventually go "phoop". Not a lot of power, really, and one minute everything sounds great and the next, no tweeter. It just disappears, like a fuse.

Seems like cone tweeters and domes work OK with first-order filters. They aren't really designed for all that much power anyway. Midrange and woofer cones are always good with first-order, or even no crossover at all. But compresson drivers don't like these single-cap crossovers very much. And ribbons, you can't even think about first-order. You can actually be using a higher-order crossover and just think about the mere possibility of a first-order and the ribbon will blow. They really don't like 'em.

I suppose it's probably fine for small signal SET owners to use single-cap crossovers on compression tweeters, but if you ever connect to something with a little more power, you're in trouble. Too much low frequency energy passes, even with a way-too-high crossover point. So the dynamic range is kinda limited, and I don't like that. I concluded a long time ago that I had to find other solutions.

Any of you guys had any luck with more than a handful of watts to your compression tweeters on a first-order filter?

Bill W.

For example, it pretty common for tweeters to have 10dBs over the woofer. Put an L-Pad in to match SPL levels, and the tweeter only receives 10% of power. So, while the woofer might be getting 50W to 100W, the tweeter only receives 5W to 10W.

Gar.

This has nothing to do with it. It's in the construction of the tweeter and materials used, Like Wayne says the cone or dome tweeters seem like they can handle it better, where as you get into compression drivers and ribbons the diaphram materials are so thin it won't take much flexing (from the lower freqs. below the x-over point) they'll rip themselves apart on a first-order.

Bill W.

Consider that a first-order crossover with 10dB padding is -16dB an octave below crossover. The same thing but with a third-order filter is -28dB one octave below. The tweeter with the third-order filter is receiving less energy one octave below crossover (-18dB) than the first-order filter (-6dB), even if the first-order solution is padded 10x (-16dB).

It's not that the first-order solution is without merit. It's just that you can't hit the dynamic range peaks with a compression tweeter using a first-order crossover as you can with a higher-order slope.

The power reduction afforded by a capacitor at 6dB per octave is generally adequate to counter the rising program power input, on average 3dB per octave, as one goes lower in frequency, giving a net reduction of 3dB per octave, assuming a reasonably robust voice-coil. However, since excursion increases by a factor of 4(6dB) per octave as frequency drops for equal power input then even with a net power input reduction of 3dB/octave the excursion demand will rise at 3dB/octave. That being the case I wouldn't consider a 1st order filter unless the corner frequency was set to at least 4 times Fs.

On the other hand, you can go to the other extreme as well with a very high order crossover. Neville Thiele has recently shown that with a 5th order high-pass you can run the corner frequency very close to the Fs without any difficulty from either the power or excursion standpoint, and the additonal octave or two of operating range thus afforded can well offer the opportunity to run two-way rather than 3-way. This works very well with a 3rd order low-pass on the woofer as far as integration goes, and offers a parts cost reduction as well compared to a 4th order/4th order arrangement due to the lessened high value inductor count.

Dave :^)