Radian 950PB on 350hz tractrix horn

December 2021

I had bought three Autotech 350Hz tractrix horn for my rear and center channel. I use a pair of Radian 760PB NEO for the rear (900Hz-4KHz) and a Radian 950PB for the center channel.

I've figure I should post the measurement here. I picked the Tractrix profile because I wanted to compare it to the JMLC horn I already had and also because it was smaller (half size) and easier to install for my center channel as you can see on the picture above. I have a big Krell amplifier and it use space on top of my center channel bass bin.

Above are the Autotech provided graph

One can see that the JMLC is much flatter while the Tractrix isn't. (Even if the compression driver isn't the same, both horn give different loading effect. Beside FR, beaming is quite different too)

Sadly, Autotech doesn't provide much details about the measurement condition and doesn't share distortion plot.

Below are my result with THE SAME Radian 950PB and measured at 11' distance (my listening position) at a realistic 90dB at 1KHz.

No EQ or any filtering was applied and measurement aren't gated.

To the left (Red= tractrix, Green= JMLC)

Frequency response, like the Autotech provided graph, you can see how much flatter the JMLC is.

The JMLC curve require much less EQ even if the Tractrix is more efficient from 1.2KHz to 6KHz. (EQ can get both flat)

To the left (Red= tractrix, Green= JMLC)

Step response, you can see the Tractrix recover a tad quicker.

To the left (Red= tractrix, Green= JMLC)

Distortion, the JMLC win hands down below 1KHz and above that, it's about the same.

Subjectively, after using DSP to achive flat response, I think I still prefer the JMLC but I have much more tweaking and test to do before I draw a firm conclusion.