Test Bench: The New CD-2514Nd/PK 1.4" Compression Driver from Beyma

For this Test Bench, Beyma sent us the second transducer from its next-gen line up of high-performance compression drivers, the 1.4” throat high power handing CD2514Nd/PK polymer diaphragm compression driver shown in Photos 1-3. (The first transducer was the CD-314Nd/Ti featured in the April 2025 issue).
  For testing, I used the same horn as in the previous CD-314Nd/Ti explication, the 1.4” throat injection-molded reinforced polycarbonate TD-1464P 60° × 40° horn with an 800Hz cutoff frequency and a 12.7 directivity index. The horizontal and vertical directivity maps can be seen in Photo 4 and Photo 5, respectively. This horn is also conveniently marked so the user will get the orientation correct. Since this horn data was presented previously, I will only feature the horizontal plane measurements with the CD-2514Nd/PK.
 
As with the Beyma CD-314Nd/Ti, the CD-2514Nd/PK is designed for applications that include use as a high power high-frequency driver in small to large venue PA systems. Features for the new Beyma CD-2514Nd/PK compression driver include a 1.4” (36mm) throat diameter driven by a 63.5mm (2.5”) diameter copper-clad aluminum voice coil wound on a non-conducting Nomex former. This assembly drives the field replaceable FEM-optimized advanced high temperature Polymer diaphragm and surround (Photo 3).

Other features include a lightweight computer FEA-optimized neodymium ring magnet motor structure (net weight is 4lbs) that includes a copper shorting cap (Faraday shield) and the patented Deplocex thermal technology shown in the diagram in Photo 6 for lower power compression and increased power handling.
  Other features include a 80W AES power handling crossed above 0.8kHz, 100W AES above 1.2kHz (160W program above 0.8kHz, 200W program above 1.2kHz), a 0.8kHz recommended crossover frequency (with a minimum 12dB/octave high-pass network), a 1W/1m 109.5dB sensitivity (with the Beyma TD-385 horn), an aluminum cover sporting a new 3D logo, plus standard solderable terminals.

Testing began as usual by using the legacy LinearX LMS analyzer to produce the 300-point stepped sine wave impedance plot shown in Figure 1, with the solid black curve representing the compression driver mounted on the TD-1464 horn and the dashed blue curve representing the driver without the horn. With nominal 8Ω impedance the CD-2514Nd/PK/TD-1464P combination has a 4.33Ω Re and minimum impedance of 5.17Ω at 10.1kHz.
  For the first group of SPL measurements, I free-air mounted the Beyma CD-2514Nd/PK/TD-1464 combination without an enclosure and measured the horizontal 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 the GRAS 46BE microphone (supplied courtesy of Loudsoft and GRAS Sound & Vibration).

Figure 2 displays the on-axis frequency response of the compression driver/horn, which shows a smooth ±2.5dB response from 800Hz to 10kHz. Figure 3 depicts the 0°-60° on- and off-axis response in the horizontal plane with Figure 4 giving the normalized horizontal plane response. Figure 5 shows the 180° horizontal polar plot (measured in 10° increments with 1/3 octave smoothing applied), which I obtained using the CLIO Pocket analyzer and accompanying CLIO microphone (courtesy of Audiomatica SRL). Again, since the TD-1464 horn has been featured previously, I am not going to display the vertical plane plots.
 
The last of the SPL measurements, Figure 6 depicts the two-sample SPL comparison showing the two Beyma CD-2514Nd/PK/TD-1464 compression driver samples to be closely matched within 0.5dB to 1dB or less throughout the driver’s operating range up to 9kHz, with some wider deviation above that frequency.
 
For the remaining sequence of tests, I again set up the Listen AudioConnect analyzer and ¼” SCM microphone (provided to Voice Coil courtesy of Listen, Inc.) to measure distortion and generate time-frequency plots. For the distortion measurement, the Beyma CD-2514Nd/PK/TD-1464 combination was again mounted in free air in the same manner as was used for the frequency response measurements. I set the SPL to 104dB at 1m (1.34V), determined by using a pink noise stimulus generator and internal SLM in the V22 SoundCheck software, and then measured the distortion with the Listen microphone placed 10cm from the mouth of the horn. This produced the distortion curves shown in Figure 7.
 
After completing this test procedure, I then set up SoundCheck V22.02 to generate a 2.83V/1m impulse response curve for this driver/horn combination and imported the data into Listen’s SoundMap Time/Frequency software. The resulting CSD waterfall plot is given in Figure 8 and the Short-Time Fourier Transform (STFT) plot is provided in Figure 9.
  Looking over all the objective measurement data presented here, the new Beyma CD-2514Nd/PK compression driver is clearly a well-engineered 1.4” compression driver, exhibiting good performance, outstanding build quality, the kind of power handling required for large venue PA systems. Add to that the very nice timbre sound quality of the Polymer diaphragm and this is a great new addition to Beyma’s extensive catalog of compression drivers. For more information about this and other Beyma OEM pro sound products, visit the company website at www.beyma.com. VC

This article was originally published in Voice Coil, July 2025