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So halfway through my August vacation and I've reached a major milestone: all measurements are DONE! Should have been done a while ago but I ran into a hiccup with the NE19 and some ripple around 6-12khz. Turns out these must be perfectly flush, not just with the baffle surface but most importantly with the cutout itself. No gap around the outside of the flange at all. I had used a standard size Forstner bit and it ended up slightly too large, with maybe a 1mm gap around the tweeter flange. It didn't meet my normal asthetic standard, but since this was the second build of all the cabinets (to accommodate the NE19 change over DQ25) there was no way I was doing it a third time. I just decided to watch out for problems, and well if it wasn't for bad luck I wouldn't have none 
Anyway tweaks were made, problem solved, and an important lesson relearned regarding diffraction, especially of small tweeters. Next time I'll be sure to use a metric Forstner bit of the exact size.
I'm already satisfied with the selection of the NE19 over the DQ25. These small baffles are diffraction nightmares, but the NE19 stays quite smooth, while the DQ25 developed quite a ripple that was hard to tame, and left me a bit unsatisfied. Infinite baffle measurements are one thing, but sometimes the diffraction profile of the baffle complements the profile of the tweeter, and some times they combine to make a worse profile than either thing separately. The other highlight was during measurements. Often with a tweeter you can tell something about their character while listening to them with MLS signals. The NE19 sound very smooth. Solid, with no resonances, or spitty character. For the matter the FR88 were excellent also, just like listening to a waterfall. Given that a lot of the crossover work was done already with the version that used the DQ25, these will be close to plug and play, just retweak the tweeter circuit.
No Quarters are coming along nicely. The Eminence Deltalite II 2512 & B&C DE160 version is again pretty much plug and play since I've been listening to the 3012HO/DE160 version for almost a year now. For the Kappalite 3012HO & Beyma CP380M version I have two active crossovers developed, which will be fired up for the first time tonight! One version is an optimized LR4 (using delay) which I won't spend a lot of time with in the near future. The one I'll be working with most right away is using the 3rd order LR filter mentioned previously with no delay. The results of listening to this will help quicken the development of the passive version using that same filter alignment. Once it is perfected in the active version, it is easy to use that as the acoustic target for the passive version. The TD12M/CP385Nd will be last to finished.
Almost to the finish line...
Anyway tweaks were made, problem solved, and an important lesson relearned regarding diffraction, especially of small tweeters. Next time I'll be sure to use a metric Forstner bit of the exact size. I'm already satisfied with the selection of the NE19 over the DQ25. These small baffles are diffraction nightmares, but the NE19 stays quite smooth, while the DQ25 developed quite a ripple that was hard to tame, and left me a bit unsatisfied. Infinite baffle measurements are one thing, but sometimes the diffraction profile of the baffle complements the profile of the tweeter, and some times they combine to make a worse profile than either thing separately. The other highlight was during measurements. Often with a tweeter you can tell something about their character while listening to them with MLS signals. The NE19 sound very smooth. Solid, with no resonances, or spitty character. For the matter the FR88 were excellent also, just like listening to a waterfall. Given that a lot of the crossover work was done already with the version that used the DQ25, these will be close to plug and play, just retweak the tweeter circuit.
No Quarters are coming along nicely. The Eminence Deltalite II 2512 & B&C DE160 version is again pretty much plug and play since I've been listening to the 3012HO/DE160 version for almost a year now. For the Kappalite 3012HO & Beyma CP380M version I have two active crossovers developed, which will be fired up for the first time tonight! One version is an optimized LR4 (using delay) which I won't spend a lot of time with in the near future. The one I'll be working with most right away is using the 3rd order LR filter mentioned previously with no delay. The results of listening to this will help quicken the development of the passive version using that same filter alignment. Once it is perfected in the active version, it is easy to use that as the acoustic target for the passive version. The TD12M/CP385Nd will be last to finished.
Almost to the finish line...
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