Pictured above is the internal section of the Celestion CDX1-1425. The copper shorting ring inside the gap can clearly be seen.

​

Impossible to see on the picture but the magnetic gap contain ferrofluid. I'm thinking of removing it but I'm hesitant since I like the CDX1-1425 so much.

​

This is a small format 35mm aluminum dome, compared to the more common 44mm. As with all dome, it has a small resonance. I found it measured at 16.6 kHz.

​

Inside the chamber, I was surprised to find no absorbent material whatsoever. I thought the conditions to be unacceptable, and as a result, it was time to mod the Celestion.

​

I used 4 mm thick self-adhesive felt pad (the one you use to put under furniture leg), cut into a 16mm diameter with a hole punch. I thought that cutting a larger piece may restrict the air volume and impede performance at low frequency.

16mm match the concave cavity inside the motor assembly, I felt this amount was the minimum size for a first attempt. 

 

WOW. Did it ever work well. That was really effective. The result speaks for themselves.

​

I await my custom JMLC horn to properly assess, as the CDX1-1425 require a negative exit angle, requiring a special horn to avoid too much diffraction.

​

More to come.