Soliloquy-II (Tang Band W5-1685 with Seas 27TBFC)


This is my third attempt with the Tang Band W5-1685. I never felt I was getting the best out of it. Having listened to it in a 10 liters ported box, I think I hit the sweet spot. Let’s see whether I can get the sound I want with a passive crossover.

Fig 1 – Tang Band W5-1685 RAW and Low Pass Response

The Black plot in Fig 1 is the RAW response of the W5-1685. The Blue plot is with my low pass filter. I had to use additional networks to tame the Breakup Peak at 8kHz otherwise it will intrude into the tweeter.

Fig 2 – Seas 27TBFC RAW and High Pass Response

The Black plot in Fig 2 is the RAW response of the Seas 27TBFC tweeter. The Red plot is with my high pass filter. 

Fig 3 – W5-1685 Low Pass with 27TBFC High Pass Plots

Fig 3 shows the two drivers crossing acoustically at 3.5kHz but that’s deceiving. If the dip at 3kHz is filled in, the W5-1685 and the 27TBFC will be crossing at 2.5kHz, which is my intended target.

Fig 4 – Summed Overlay

The Black plot is summed response of the W5-1685 and the 27TBFC. There are no cancellations in the crossover passband. Measurements below 500Hz includes my room reflections. Ignore the deep notch at 150Hz. That’s a floor bounce that the mic picked up.

For a better idea of the bass, I spliced in the blue Nearfield response below 500Hz. Room reflections are not included in Nearfield measurements.

Fig 5 – Soliloquy-II Frequency Response

Fig 5 is the final frequency response of the Soliloquy-II. Taking 85dB as the reference, there is some emphasis in the lower treble (1kHz~3kHz) and a slight dip from 7kHz~8kHz. I don’t worry too much about that. There’s not much information there anyway. 

Fig 6 – Soliloquy-II Null Plot

To check on how well the two drivers are crossing, I flipped the tweeter wires around. It resulted in a nice notch at about 2.5kHz (Fig 6). They are not exactly time aligned but very close. 

Fig 7 – Soliloquy-II Step Response

Fig 7 is the Step Response of the Soliloquy-II. This is where we can see it made a quantum leap. By using passive components, I was able to reduced the delay in the W5-1685 substantially.

When compared to the previous Step Response using a 24dB/oct active crossover (Fig 8), the reduction in the W5-1685 delay is shocking. This was what was troubling me when I heard the active version. I knew something was not quite right with the music. 

Fig 8 – Active 24dB/oct W5-1685 with 27TBFC Step Response

Fig 9 – Soliloquy Toneburst Energy Storage plot

The Toneburst Energy Storage plot in Fig 9 shows minimal stored energy in the treble. These are the light blue slices from 5kHz~9kHz and another bunch from 10kHz~20kHz.

Fig 10 – Soliloquy-II Spectrogram

When plotted against time, the stored energy in the treble is insignificant. From 3kHz onwards, they dissipate at 2ms. It is from 1kHz~3kHz that shows some cone ringing. However, they are not serious. They don’t last more than 6ms. 

The Sound of the Soliloquy-II

This is one design that will turn heads. Where’s the bass coming from? Is there a subwoofer somewhere?

The tonal balance is perfect. One doesn’t need to strain one’s ears to hear the bass. The bass is there but it is well separated from the midrange. That’s important, otherwise the vocals will be muffled. There’s meat in the bass and it’s fairly well controlled. I can hear the texture of the bass clearly in Britney Spears Baby One More Time.

For the vocals, I chose Suddenly by Billy Ocean. In the recording, his voice is slightly recessed. If a speaker is not well designed, the lyrics will be quite hard to make out. No problem with the Soliloquy-II. Suddenly not only came out clear, it’s heartrending.

For the treble, I played Samba del Viento from the album Blue Desires by Tino Izzo. This is one track that I found extremely difficult to reproduce cleanly. If my tweeter is not good enough, I can pick up distortions. I am happy to say the Seas 27TBFC in the Soliloquy-II performed splendidly.

Can the Soliloquy-II be even better?

Yes. I would like to hear more of the 40Hz~50Hz. Then, it’s complete. I find that when the bass extends down to 40Hz, it sounds more natural. 

Maybe a very special bandpass subwoofer will do the trick. Well, something to think about. As it stands now, the Soliloquy-II is already a solid performer.

Updated on Mar 30,2020

The Icing on the Cake

I couldn’t help but drag out one of my bandpass subwoofers to augment the low bass. This particular subwoofer uses a vintage Pyramid 10″ car subwoofer that I have for many years. I remember when I worked on it a few years back, there was a peak at 50Hz. And true enough, there it is when I found the plots. 

Fig 11 – Pyramid Gold Bandpass subwoofer response

For the Soliloquy-II, I chose the Violet plot in Fig 11. That is with my 24dB/oct electronic crossover at 95Hz Low Pass. On playback, it came out perfect. It added just the right amount of weight and thump for the low bass. The upper bass is not affected because no electronic high pass is used on the Soliloquy-II. It can’t get better than this. I can sleep blissfully tonight.

Unless otherwise stated, all measurements were made with the mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied.