The Adana Mark II was a product of experimentation with the Adana. I had intended to make one pair, but a couple more friends wanted something similar, so I kicked off the project by getting two pairs of enclosures built.
Therefore, we now had two pairs of the Adana. It would have been my first case of making more than one pair of any of my designs. But while working on the crossover of the Adana, I began to get fresh ideas after building the first pair, and so I re-designed the crossover. So, I now had an Adana build and a Mark II build which differed purely in the crossover. Everything else remains absolutely unchanged.
This, ladies and gentlemen, is the Adana Mark II. I have no intention of repeating details like drivers, enclosure and measurements here. I will go straight to the crossover.
The crossover
The new crossover turned out like this:
One can see the following changes:
- The woofer’s LPF has an electrical second-order circuit now, whereas the Mark I had a fourth-order.
- The midrange to tweeter crossover had earlier been an electrical second order LPF and third order HPF, but now both were fourth order electrical.
- The notch is now using a smaller value of inductor, though it’s hitting the same frequency.
- Because of the steeper slopes now possible on the LPF of the midrange, the cone breakup of the RS125 is now suppressed more effectively than in the Mark I. This will have a small impact on the texture of the upper mids.
The crossover frequencies continue almost unchanged, at about 320Hz and 2.9KHz
The SPL from this crossover turns out to be:
And the impedance plot is now:
Therefore it continues to be as difficult a load to drive as Mark I.