NM-1 (Natural Music)
Tang Band W5-2143 with HiVi F8
The NM-1 is the most natural sounding loudspeaker I’ve ever designed. It marries the unique properties of a full range with a woofer. It took me months of auditioning to find the best woofer. I tried 6″ and 8″ and finally settled on the HiVi F8. Though the F8 cost almost half of the Tang Band W5-2143, don’t let the low price fool you. It’s the sound that matters.
 Fig 1 – W5-2143 RAW Response • 6 Liters Sealed Box • Baffle Width = 8″
To recap, Fig 1 is the RAW response of the Tang Band W5-2143. As I mentioned before, this will end up “shouty”. That needs to be addressed.
 Fig 2 – MN-1 Frequency Response (W5-2143 with HiVi F8)
Fig 2 is the Frequency Response of the NM-1. We can see the effects of the Baffle Step has been tamed. Lower down from 100Hz~50Hz, the amplitude of the bass is much more than using the W5-2143 alone. This bass comes from the HiVi F8. Right now, the F8 is in a 35 liters bass reflex tuned with a 3″ PVC tube of 7-3/4″ length.
This response is all done passively. No active crossovers, electronic equalizers or DSP are used. Disregard the notch at 150Hz. That’s caused by a floor bounce in my measuring setup.
 Fig 3 – HiVi F8 with 10mH Frequency Response
Fig 3 is the response of the F8 with a single 10mH iron core inductor. I opted for a 1st order low pass filter because after extensive listening, this sounds the most natural.
 Fig 4 – NM-1 Harmonic Distortion
The Harmonic Distortion (Fig 4) is quite impressive. 2nd Harmonic is at -50.5dB below the fundamental. 3rd is even lower at -60.9dB.
 Fig 5 – NM-1 Toneburst Energy Storage
The Toneburst plot (Fig 5) looks very similar to that of the W5-2143. Where it differs is an additional bunch of light blue slices centering at 4kHz.
 Fig 6 – NM-1 Waterfall
The Excess Energy at 4kHz is seen in Waterfall plot (Fig 6) as artifacts at the same frequency. It doesn’t last long enough to be heard.
 Fig 7 – NM-1Spectrogram
The Spectrogram (Fig 7) doesn’t flag any serious issues in the treble. In fact, the additional artifacts at 4kHz are not seen.
 Fig 8 – NM-1 Step Response
Fig 8 is the Step Response of the NM-1. Bear in mind that this step is with the F8 woofer added to the W5-2143. Note the instant step of the W5-2143 remains unchanged.
Summary
Adding a woofer to the W5-2143 may seem like an easy task but it’s not so straight forward. If it’s not done right, the bass will lag the midrange, similar to a delay. It’s quite audible and I find it distracting.
With the NM-1, the bass and the midrange is seamless. She sounds like Phase and Time Coherent loudspeakers, just simpler in execution.
Unless otherwise stated, all measurements were made in Full Space (4pi). Mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied. |
