Test Bench: Fountek NeoCD2.0 High-End Ribbon Tweeter

The transducer to be characterized in this article is a high-end ribbon tweeter from a high-end transducer OEM, based in Shangai, China, Shanghai Nada Technology Co., Ltd. (formerly Fountek Electronics Co., Ltd.). Shanghai Nada Technology is really a dedicated high-end manufacturer of both high-end transducers (woofers, midbass drivers, full-range drivers, and ribbons high-frequency devices), powered and passive speakers, and high-end MOSFET and tube amplifiers, which includes a 67lbs KT-88-based 80W stereo amplifier (the Altitude 3500)! The company was founded in April 2003 with a mission statement to supply strictly high-end two-channel products. The company released its first ribbon transducer, the JP3.0, in June 2003, followed by its JP2.0 ribbon transducer in October 2003, and its NeoPro 5i released in October 2004. The NeoX3.0 ribbon was featured in the July 2016 issue of Voice Coil magazine, and the NeoPro5i in the July 2023 issue.
 
The device that was sent to Voice Coil is the company’s current iteration of its Fountek (Shanghai Nada Technology’s brand name for its drivers) NeoCD 2.0 ribbon tweeter (Photo 1 and Photo 2). The NeoCD2.0 utilizes a 120mm×8mm 0.015mm thick reinforced sandwich (960mm2 radiating area) ribbon diaphragm. You can also see that the NeoCD2.0 uses a closed-back injection-molded rear cavity with two aluminum heatsinks and a built-in transformer. Other features for this design include the neodymium motor system, a cosmetically attractive 165mm×85mm 5mm thick black aluminum faceplate, a black mesh screen protecting the diaphragm, 97dB 2.83V/1m sensitivity, rated 20W nominal power handing (50W maximum), recommended crossover frequency of 2.5kHz @ 18dB/octave, and a pair of color-coded screw on terminals. This is a heavy high-frequency device, weighing in at 2.3lbs.
  I commenced analysis for the Fountek NeoCD2.0 by performing a 300-point impedance curve depicted in Figure 1 using the legacy LinearX (RIP Chris Strahm) LMS. The primary resonance occurs at 400Hz with a small secondary resonance of 1kHz. Measured DCR for the NeoCD2.0 is 0.16Ω, which is typical of this kind of transformer coupled ribbon device. This is not an issue once a crossover is applied; however, you need to be aware of this when you are characterizing this type of transducer and limit your analyzer’s frequency range to, in this case, about 100Hz. The minimum impedance above the primary resonance was a normal 7.05Ω at 3.89kHz.
  Following the impedance measurement, I mounted the Fountek NeoCD2.0 in an enclosure with a 18”×10” baffle area and proceeded to measure the on- and off-axis SPL with sweeps at 0°, 15°, 30°, and 45° on and off-axis frequency response, again using the Loudsoft FINE R+D FFT analyzer (courtesy of Loudsoft) and GRAS 46BE ¼” microphone (graciously provided by GRAS Sound & Vibration). The instrument was set up to measure the 200Hz to 40kHz frequency response (using a 192kHz sampling rate) at 2V/0.5m, normalized to 2.83V/1m. Data was then taken in both the horizontal and vertical planes. Figure 2 shows the horizontal on-axis response of the Fountek ribbon transducer. The frequency response of the NeoCD2.0 is ±1.7dB from the recommended crossover at 2.5kHz up to 10kHz and ±3.6dB from 2.5kHz to 40kHz. There is small peaking in the response centered on about 18kHz, so some equalization would be useful for that and the slightly rising response above 8kHz.
 
Figure 3 depicts the on- and off-axis frequency response in the horizontal plane, which is good out to 30° off-axis. See Figure 4 for the normalized 0° to 45° frequency response, and the CLIO Pocket-generated horizontal polar plot shown in Figure 5 (1/3 octave smoothing applied). Because the aspect ratio of the NeoCD2.0 aperture is like most ribbons and AMTs, there is substantial directivity in the vertical plane. This can be seen in the vertical plane for the on- and off-axis 0° to 45° curves depicted in Figure 6, the same curves normalized in Figure 7. The two-sample SPL comparison is given in Figure 8, indicating that both NeoCD2.0 samples were closely matched within the relevant operating range within ≤1dB.
 
Next, I initialized the Listen SoundCheck analyzer (SoundCheck 21 software) with the SCM microphone and AudioConnect USB interface (all provided courtesy of Listen, Inc.). With the SPL set to 94dB/1m (2.1V) using the built-in pink noise generator and SLM utilities, I then relocated the ¼” SCM microphone to 10cm from the face plate of the Shanghai Nada Technology Co., Ltd. Fountek NeoCD2.0, and ran the distortion curves seen in Figure 9.
 
For the last two measurements on the ribbon tweeter, I performed an impulse measurement, and then imported this into the Listen SoundMap software, windowed out the room reflections, and created the cumulative spectral decay (CSD) plot depicted in Figure 10 and the Short-Term Fourier Transform (STFT) shown in Figure 11.
 
Ribbon and AMT high-frequency devices are well known for the good transient performance and clarity in the vocal range. Looking at the data collected for the Fountek NeoCD2.0, along with the excellent build quality, the NeoCD2.0 would make an effective high-frequency device for use in a two-way system incorporating 5.25” to 8”, with 6.5” woofers being the sweet spot for this transducer. For more information about this popular high-end high-frequency ribbon tweeter from Shanghai Nada Technology Co., Ltd, visit www.fountek.net. VC

This article was originally published in Voice Coil, September 2023.