Frequency response

Impedance

Off axis plots

OW2

XT19

MDT30

Nonlinear distortion

at 1.5k

OW2-not done

XT19

MDT30

2k

OW2

XT19

MDT30

2.5k

OW2

XT19

MDT30

3k

OW2

XT19

MDT30

3.5k

OW2

XT19

MDT30

4k

OW2

XT19

MDT30

5k

OW2

XT19

MDT30

7k

OW2

XT19

MDT30

Conclusion

Unlike tweeter test one, where there really wasn't anything unexpected, there were a number of surprises.

1. While having acceptable 2nd and 3rd order distortion products, the ow2 had high number of higher order distortion products. I did not expect this for everyone's darling (mine too!) In fact, on 3rd order and higher, the ow2 turned in a worse performance than the xt19 and the mdt30 at virtually every frequency.

2. The xt19 had very good distortion numbers-in some cases better, in some cases, slightly worse than it's larger sibling.  Overall though, in the same ballpark as it's larger brother. This is both peculiar and good news. Peculiar in that diaphragm excursion should be higher for any given spl than the xt25. It's good news because the xt19 distinguishes itself from its brother in a very important way, namely significantly better off axis performance. While I wasn't really suprised that its off axis performance is better, it is notably better. It's as good as most 1" domes, if not a bit better.

3.  The linear distortion of the xt19, though very good, didn't quite match the xt25. Not suprisingly, the ow2 had the best overall linear distortion performance, but the xt19 was very close.

Some general comments and opinions. What to make of the ow2's mediocre nonlinear distortion performance?  Well, think about this. Perceived detail and "air" can occur for a number of reasons.  Good off axis performance can do this. Good linear distortion performance can do this. But modest amounts of higher order nonlinear distortion can also increase apparent detail. In this fashion, I suppose the ow2 is the winner. But only in the sense that "it gives you all the detail that's in the recording, and then some..."  Anyway, I find the nonlinear performance disappointing for the ow2. The xt19 on the other hand, is fairly close to the ow2 in off axis performance and linear distortion, but has an overall better nonlinear distortion spectrum. The only asterisk as far as the xt19's nonlinear distortion performance is it's mediocre 2nd order performance. But if I had to pick between a little bit of 2nd order distortion or multiple higher order products, I would pick the 2nd order products. And the price of the xt19 is a bargain-less than $50. Does this mean the xt19 is a "poor man's hiquphon?" No, actually I think the xt19 is better than that. Neither tweeter is perfect and depending on your priorities, the xt19 may be better in absolute terms as well as cheaper. Or, it may not, if you value off axis and linear performance so strongly and you're willing to accept some higher order distortion products.

I see no reason why the xt19 can't be used in a 2 way at 2.5k and a fourth order acoustic slope with good effect. I think this would be more well received than the xt25; while a very good tweeter, I think the very limited dispersion of the xt25 turned alot of listeners off. Since the xt19 doesn't seem to require much higher of a crossover than the xt25, it's probably a better choice unless you want "controlled directivity." One note though. You can see the xt19 and the morel did poorly at 1.5k. I didn't even bother with the ow2 because it didn't fare so well at 2k. It's possible that the xt25 might turn in a better performance at 1.5k than the xt19.

What about the morel? A good tweeter. Better nonlinear distortion than the ow2, though not as good as the xt19--unless you're going to cross low and/or with a shallow slope. About the same directivity as the xt19. Nonlinear performance is still good, though may not be as good over 8.5k than the other two. (This issue of linear distortion is turning out to be a little less clear cut that it first appears. Frequency response variations can affect the results and it becomes very difficult to make a meaningful distinction between small differences on the graphs.)