I recently came across this website, while I'm not technically minded, it may prove useful. Share your opinion.

http://misty.com/people/don/pzfix.html

I am investigating three posible causes:
1. The 1038 is just more efficient than the Alpha 10-A. This can be corrected with just a cap in series with the piezo--as Wayne already explained below.
2. The plastic housing of the 1038 is resonating. This might be cured by applying a mixture of silicone calking and sand to the extrior of the back side of the 1030 for damping.
3. The Alpha 10-A and the 1038 may overlap a bit too much. The Alpha 10-A has fairly flat response up to 5KHz while the 1038 is prety flat from 3.5KHz up. I make this comment based only on the published response curves of the drivers and my intepretation of them. Any feed back on this posibility will be most appreciated.

Items one and two are simple to experiment on. Item three, however would be difficult to "fix" or even verify. I'll borrow a real time analyzer to check it out.

The KSN-1005 with its long snout is the one I never really liked. It is more efficient, but sounds noticably different. There are some others that I don't like, such as the versions that aren't horn loaded and most of the generic knock-offs. But I like the Motorola KSN-1038 and I've stuck with them for the low cost two-ways for over twenty-five years. There's just a sound that I like and a simplicity of the design that appeals to me.

There is a slight rise in both the current Alpha 8 and the Alpha 10 in the upper vocal overtone region, around the 2kHz to 4kHz octave, just before upper cutoff. That's what the 0.5mH coil is for. I find the one π and two π speakers to be very pleasant, and I've always been proud of them. But if you want to build a more expensive speaker, you can always make different choices.

As for me, I think the one π's and two π's are perfect, just the way they are. I can't think of any better set of parts that gives so much satisfaction for fifty bucks.