So, I got hold of the old Paul Carmody Sprite speaker I had built last year and given away to my brother. It was based on a TD7498 bluetooth amp with the Dayton ND90-8 drivers. The Sprite contour filter (BSC) was a 0.9mH coil in parallel to a 16 ohm resister. The plan was to make it into a 2-way speaker with the addition of an AMT-8 tweeter. I thought I'd give it try with the old box before I built a completely new one for me. The tweeter would be placed outside with all the other added components.
I added the 0.3mH LPF before the BSC on the ND90-8 and a 2.2uF cap on the tweeter. This is a 1st order Solen Split crossover at around 6200 Hz. It gives a 2LR sort of -6db dip at the crossover point. The only difference is that the slopes are like the Butterworth 1st order slope. I padded down the tweeter with a 12db L-Pad (6 ohm resistor in series with 2.7 ohm resistor in parallel).
The sound has gone from good boombox type sound to really great. The bass is more defined, the mids are now more clean and the treble has got so much of space and clarity. I'm listening to them with a big grin and can imagine that they would make superb separates. 
Now to build my own box for them and put all the guts in. My suggestion to all those who started out with the Sprite build, try this out. Its a huge improvement over the Sprite sound, though it adds to the cost as you've got to buy tweeters, extra LPF coils, HPF caps and the L-Pad resistors. But, its worth it.
 
I added the 0.3mH LPF before the BSC on the ND90-8 and a 2.2uF cap on the tweeter. This is a 1st order Solen Split crossover at around 6200 Hz. It gives a 2LR sort of -6db dip at the crossover point. The only difference is that the slopes are like the Butterworth 1st order slope. I padded down the tweeter with a 12db L-Pad (6 ohm resistor in series with 2.7 ohm resistor in parallel).
The sound has gone from good boombox type sound to really great. The bass is more defined, the mids are now more clean and the treble has got so much of space and clarity. I'm listening to them with a big grin and can imagine that they would make superb separates. 
Now to build my own box for them and put all the guts in. My suggestion to all those who started out with the Sprite build, try this out. Its a huge improvement over the Sprite sound, though it adds to the cost as you've got to buy tweeters, extra LPF coils, HPF caps and the L-Pad resistors. But, its worth it.
 
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