Test Bench: Wavecor TW030WA12 30-mm Cloth Waveguide Loaded Tweeter

January 19 2016, 04:00

This Test Bench is about the new Wavecor TW030WA12, a new 30-mm cloth waveguide loaded tweeter intended for home audio applications. The TW030WA12 is the 8-Ω version and the latest addition to Wavecor’s 30-mm tweeter lineup (see Photo 1). The TW030WA11, which is the 4-Ω version, was featured in the November 2014 Voice Coil issue. The TW030WA08, which is the original full rear cavity version of this 30-mm tweeter, was featured in Voice Coil’s December 2009 issue. The TW030WA09, which is the non-cavity low-resonance version, was tested in the August 2012 issue of Voice Coil.

 
Photo 1: Wavecor’s TW030WA12 is the 8-Ω version and the latest addition to Wavecor’s 30-mm tweeter lineup.

Prior issues detail Wavecor’s corporate background information, which is basically the interesting synergy between a China speaker manufacturer and two experienced Danish engineers, both formerly with Vifa. Features for the Wavecor TW030WA12 tweeter include a 30-mm wide surround precision-coated cloth diaphragm optimized for high-frequency cut-off above 20 kHz, internal chambers below the dome and surround, a copper-clad aluminum voice coil winding with a vented voice coil former, flexible lead wires for large excursions with crossovers below 3 kHz, black anodized motor parts for enhanced cooling, and goldplated terminals. Its most differentiating feature is a waveguide faceplate for increased sensitivity and directivity.

I commenced testing using the LinearX LMS analyzer to produce the 300-point impedance sweep for the TW030WA12 (see Figure 1). The TW030WA12’s resonance occurs at a low 425 Hz. The TW030WA12’s factory quoted QTS is 0.9. The TW030WA12’s direct current resistance (DCR) was 6.41 Ω with a minimum impedance above resonance of 6.45 Ω at 1.43 kHz.

Next, I recess mounted the W030WA12 in an enclosure that had a 14” × 7” baffle area. Then, I measured the on- and off-axis frequency response with a 100-point gated sine wave sweep at 2.83 V/1 m. Figure 2 shows the TW030WA12’s on-axis response to be a smooth and flat ±1.5 dB from 1 kHz to 20 kHz, which is a wide, flat bandwidth for any tweeter. Figure 3 depicts the TW030WA12’s on- and off-axis response, with the off-axis curves normalized to the on-axis response shown in Figure 4. Figure 5 shows the TW030WA12’s two-sample SPL comparison, indicating that both samples were closely matched.

Next, I used the Listen SoundCheck analyzer and the SCM 0.25” microphone to measure the impulse response with the tweeter recess mounted on the test baffle. Importing this data into the Listen SoundMap software produced the CSD (waterfall) plot shown in Figure 6. Figure 7 shows a short-time Fourier transform (STFT) displayed as a surface plot.

For the final test procedure, I used a pink noise stimulus to set the 1 m SPL to 94 dB (4.17 V) and measured the second- and third-harmonic distortion at 10 cm (see Figure 8). As usual, Wavecor has fielded another nice high-end product for the home audio and studio monitor markets. I have worked with Wavecor on a high-end loudspeaker project for a large manufacturer, and I can say from personal experience, that this is an excellent company. For more information, visit www.wavecor.com.
 
Figure 1: Wavecor TW030WA11 free-air impedance plot.
Figure 2: Wavecor TW030WA11 on-axis response.
Figure 3: Wavecor TW030WA11 horizontal on- and off-axis frequency response (0° = solid, 15° = dot, 30° = dash, 45° = dash/dot).
Figure 4: Wavecor TW030WA11 normalized on- and off-axis frequency response (0° = solid, 15° = dot, 30° = dash, 45° = dash/dot).
Figure 5: Wavecor TW030WA12 two-sample SPL comparison.
Figure 6: Wavecor TW030WA12 SoundCheck CSD waterfall plot.
 
Figure 7: Wavecor TW030WA12 SoundCheck STFT surface intensity plot.
Figure 8: Wavecor TW030WA12 SoundCheck distortion plot.

This article was featured on the January 2015 edition of Voice Coil.
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