Test Bench: Faital Pro HF110 1" Neodymium Motor Compression Driver

For this Test Bench, Faital Pro sent me its new 1” conical exit HF110 neodymium motor compression driver, shown in Photo 1, along with the Faital Pro STH100 horn. In terms of features, the Faital Pro HF100 is designed for use with 1.0” throat horns and has a 25.4mm throat diameter with a 34° conical exit angle.
 
The HF110 is a compact compression driver with a 72mm overall diameter and 35mm depth that incorporates a 37mm (1.4”) diameter high temperature Keytone Polymer diaphragm (Photo 2) with an annular phase plug design (Photo 3). This is driven by a 37mm diameter voice coil wound with aluminum wire on a high Qm non-conducting Kapton former powered by a neodymium ring magnet. Additional features include a 2kHz recommended crossover frequency (second-order or higher high-pass filter), a 110dB 1W/1m sensitivity (8Ω version) and a 40W AES power handling rating (80W maximum power handling), making this compression driver well suited for applications such as stage monitors and PA speakers.
  The Faital Pro horn used in conjunction with the HF110 was the STH100 elliptical Tractrix flare horn that has a 1.0” exit bolt on type mounting flange and is made from cast aluminum. This horn provides an 80° × 70° constant directivity coverage pattern, a directivity index of 8dB and a 1.4kHz cut-off frequency, making it a good match for the HF110 compression driver. The STH100 has been previously featured in Test Bench, but the horizontal and vertical beamwidth plots are given in Figure 1 and Figure 2, respectively.

Testing began using the LinearX LMS analyzer to produce the 300-point stepped sine wave impedance plot shown in Figure 3, with the solid black curve, representing the HF110 compression driver mounted on the STH102 horn and the dashed blue curve representing the compression driver without the horn. With a 5.67Ω DCR (Re), the minimum impedance of the HF110/STH100 combination was 7.3Ω and at 5kHz.
  For the next set of SPL measurements, I free-air mounted the Faital Pro HF110/STH100 combination without an enclosure and measured the horizontal and vertical on- and off-axis at 2.0V/0.5m (normalized to 2.83V/1m) from 0° on-axis to 60° off-axis using the Loudsoft FINE R+D analyzer and GRAS 46BE microphone (supplied courtesy of Loudsoft and GRAS Sound & Vibration). Figure 4 displays the on-axis frequency response of the HF110/STH100 combination, which is ±2.5dB from 2kHz to 21kHz with no major anomalies throughout its operating range from the 2kHz recommended crossover frequency to about 20kHz. 
  Figure 5 shows the horizontal SPL data from 0° on-axis to 60° off-axis, with the normalized version depicted in Figure 6. Note, since the STH100 has been explicated in Test Bench several times, I chose not to do the vertical SPL measurements, and just did the horizontal polar plot, shown in Figure 7, using the CLIO Pocket Analyzer. 
  Last, Figure 8 illustrates the two-sample SPL comparison showing the two Faital Pro HF110 compression driver samples to be very closely matched ≤1dB throughout the operating range of the transducer up to 10kHz.
  For the remaining series of tests, I set up the Listen AudioConnect analyzer, SoundCheck 21 software, and the Listen ¼” SCM microphone to measure distortion and generate time-frequency plots (courtesy of Listen, Inc.). For the distortion measurement, the Faital Pro HF110/STH100 combination was again mounted in free air in the same manner as was used for the frequency response measurements, and the SPL set to 104dB at 1m (1.92V determined by using a pink noise stimulus generator and internal SLM in the SC21 SoundCheck software).

Then I measured the distortion with the Listen ¼” measurement microphone located 10cm from the mouth of the horn. This produced the distortion curves shown in Figure 9 (red curve=second harmonic, blue curve=third harmonic). Note the very low third harmonic, in fact, so low, the second harmonic totally tracks the THD curve.

  I then set up SoundCheck 21 to generate a 2.83V/1m impulse response for this driver/horn combination and imported the data into Listen’s SoundMap Time/Frequency software. Figure 10 shows the resulting cumulative spectral decay (CSD) waterfall plot and Figure 11 shows the Short Time Fourier Transform (STFT) plot. 
  The Faital Pro HF110 exhibits excellent objective performance and is definitely a welcome new addition to Faital Pro’s extensive lineup of neo motor 1.0” compression drivers. For more information about this and other pro sound transducers from Faital Pro, visit the website at www.faitalpro.com. VC

This article was originally published in Voice Coil, December 2024