Swallow-BC – Time & Phase Coherent

Swallow-BC
Time & Phase Coherent

Can the Swallow-M2 be improved further? Yes, but I’ll have to increase the crossover components. Without the restrictions imposed by using as few components as possible, I can refine the crossover.

Fig 1 – Peerless GBS-85N25PR03-04 with BC25SC08-04

Fig 1 are the plots of the GBS85N and the BC25SC08 with their new networks. Note how much the cone breakup of the GBS85N has been reduced. The peak at 5kHz is now 10dB below the tweeter. The second peak at 8kHz is 15dB below.

Fig 2 – Summation of GBS85N and BC25SC08-04

Fig 2 shows the Summation in the crossover passband. This is a beautiful summation. No cancellations are observed on either side of the center frequency.

Fig 3 – Null Response of Swallow-BC

Fig 3 is with the BC25SC08 tweeter wired in absolute phase. It resulted in a rather deep null at 3kHz. The slopes are not smooth because of the two drivers are jagged in the crossover. There’s nothing I can do about them as they are inherent in the drivers themselves.

Fig 4 – Frequency Response of Swallow-BC

The final response of the Swallow-BC is in Fig 4. Note the absence of the notch at 1.7kHz that is in the Swallow-M2. This is a frequency response I can be proud of.

Fig 5 – Swallow-BC Waterfall

Fig 5 is the Waterfall of the Swallow-BC. Some artifacts are seen at 5kHz, 9kHz and 13kHz. I wouldn’t too much about them as they are microscopic. 

Fig 6 – Swallow-BC Spectrogram

The Spectrogram in Fig 6 recorded some bleed at about 1.5kHz. They are very weak, about 50dB below the fundamental. By 6msec, they are largely gone. 

Fig 7 – Swallow-BC Toneburst Energy Storage

Fig 7 recorded an exceptionally clean treble. There’s minimal excess energy (light blue slices) from 2kHz upwards. The ones at 5kHz do not last more than 6 cycles. These are the artifacts seen in the Waterfall in Fig 5.

Fig 8 – Swallow-BC Harmonic Distortion

The Harmonic Distortion of the Swallow-BC is in Fig 8. The THD (H2-H9) is at 0.822%. 2nd Harmonic is at 0.357% whereas the 3rd Harmonic is 0.471%.

Fig 9 – Swallow-BC Step Response

Fig 9 is the Step Response of the Swallow-BC. She looks Phase and Time Coherent, like in the Thiel speakers. This is only possible because of the low profile structure of the GBS85N. 

Fig 10 – Swallow-BC Phase

The Phase of the Swallow-BC is in Fig 10. There is one phase inversion at about 3.1kHz. This is where the GBS85N and the BC25SC08 are crossing. The other two on the left are from the peak in the BC25SC08 tweeter. I can remove them but more crossover components will be needed. I seriously doubt it will make any improvements.

Sound of Swallow-BC with Peerless 830869

The Swallow-BC is a crossover that a professional designer should achieved. No corners are cut. The crossover does cost slightly more but that is what it takes to do a proper crossover. Whether it makes any audible difference compared to the Swallow-M2 is besides the point. The measurements show a flaw in the Swallow-M2 that was corrected in the Swallow-BC.

When the Swallow-BC is blended with the Peerless 830869, the combination is made in heaven. I’m using a 24dB/oct electronic crossover set at 200Hz to cross the Peerless 830869 over to the Swallow-BC and the upper bass is perfect. Solid and punchy. The Swallow-BC has a certain warmth in the midrange that other midrange of mine doesn’t have. The Peerless BC25SC08-04 tweeter is incredible. No harshness.

One last thing, this system needs a certain loudness for the music to come alive, especially the 830869. Otherwise the bass will sound limp.

Unless otherwise stated, all measurements were made in Full Space (4 pi) with the mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied.