top of page

In my limited experience, most compression drivers perform better when the rear cover is removed.

In the case of the Celestion CDX1-1445, you can't remove the rear cover, as the diaphragm is glued on.

​

Experimenting about "venting the rear of diaphragm" then hit my mind.

After all, the Radian 760PB neo does have a vent hole in the rear cover as do many other CD’s.

The Radian 950PB’s however didn’t have a rear hole, which was a surprise when I received them.

I listened to the 950PB’s without the rear cover installed, I preferred without the cover, so drilling a hole in the cover didn't cross my mind. I also had to consider the resale value of those pricey 950PB.

​

Given the CDX1-1445 is a small diaphragm format (35mm), I arbitrary selected a 13/64" diameter hole size. (0.5 centimeter)

The impedance result in the Dats (Not shown)

​

  • The impedance peak became narrower, which is a good sign.

  • The phase flattened out a bit, this is good also.

  • Counter-intuitively, the FS increased a bit, but was still well below the 1445’s optimal operating range. No issue here.​

​

Still… here’s a rough idea of the rear cover hole mod.

Measured on the STH100 horn.

​

  • Purple is 13/64" hole in the rear cover 

  • Blue is me blocking the hole with my finger

  • Step response show great improvement

bottom of page