EV 8HD with Selenium D250X Review

Electro-Voice 8HD Midrange Horn

The 8HD is a vintage diffraction midrange horn of the 50s. Today, she’s about 70 years old, as old as the Klipsch K-700. She was used in the early Electro-Voice Patrician, Aristocrat and others.

What is interesting with this 8HD is her dispersion. She has a Horizontal Dispersion of 120° and a Vertical Dispersion of 90°. That’s quite normal. However, what’s isn’t is they are with the horn in a vertical position, standing upright as picture in the Patrician (left above). I don’t think I’ve ever come across a horn like this before. If you mount her horizontally like in the Aristocrat (right above), her Horizontal Dispersion is 90° and her Vertical Dispersion is 120°. It would be a good idea to have some carpet in front to absorb the floor reflections when mounted horizontally.

Another feature of the 8HD horn is she cuts off at 600Hz. Recommended lowest crossover frequency is 800Hz. Having worked on the Selenium D250X previously with the Klipsch K-700 horn, I’m curious to see the outcome when I mate the Selenium with this 8HD.

Early Horror

Fig 1 – EV 8HD with unbranded compression driver. No Smoothing applied. Mic at 30 ins.

I bought a pair of 8HD horns off eBay about 5 years ago. They came with some vintage compression drivers that are unbranded. They looked to me like they were from Paging Horns. Anyway, I did a sweep and to my horror, the response is disappointing (Fig 1). While she does go down to 600Hz, there is a pronounced peak at 2kHz. This is where horns get a bad rep. It would not be an issue if I’m using an electronic Parametric EQ to tame the peak but to do that passively, it’s just to much work. I set them aside while I worked on other drivers.

Fig 2 – 8HD with Selenium D250X RAW Response. No Smoothing applied. Mic at 30 ins.

Fast forward to 2026. After working on the Klipsch K-700 horn, it remember I have a pair of 8HD somewhere. I eventually found them and duly mounted one with the D250X, hoping to get a better response. I was rewarded with Fig 2. The D250X fits the 8HD perfectly, so much better than the Klipsch K-700.

Fig 3 – 8HD with Selenium D250X Impedance

Fig 3 is the Impedance plot of the 8HD with the D250X. There’s a series of peaks with the largest at about 550Hz. Nothing too serious. It remains to be seen whether I can hear the 8HD resonance when I work on her crossover. If it’s an issue, I will have to install a Series LCR.

Harmonic DistortionFig 4 – 8HD with Selenium D250X Harmonic Distortion

I was still disturbed by the high Harmonic Distortions in the Bunting III. I did another sweep with the D250X with the HD8 horn attached and I still got the same results (Fig 4). This led me to believe it’s not coming from the horn and compression driver mismatch but rather from the D250X itself. In my next post, I will address this issue head-on.

Unless otherwise stated, all measurements were made in Full Space (4 pi) with the mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied.