The Hawk-XT2 is an update of the original Hawk. The two drivers remain the same, a HiVi L6-4R kevlar midwoofer paired with a Peerless XT25TG30-04 ring radiator tweeter.
In this final version, the frequency response is greatly improved. It is much flatter than the first version. Best of all, I did this with fewer components in the crossover.
Fig 1 – HiVi L6-4R RAW Response • Baffle Width=8-1/2″
Fig 1 is the RAW response of the HiVi L6-4R in a 13 liters bass reflex. Baffle width is 8-1/2″. The L6-4R has a decent extension for a woofer of this size. The problem is there is a cone break-up peak at 2.5kHz. It would have been perfect if it is at 5kHz but at such a low frequency, I would have to cross it at 1.5kHz to prevent the peak from interfering with the response. Since I’m working with a basic crossover, I will have to contend with this peak. Hopefully, it won’t be audible when I’m finished.
Fig 2 – Blue plot=HiVi L6-4R with LPF • Peerless XT25TG30-04 with HPF
Fig 2 shows the L6-4R and the XT25TG30-04 crossing at about 2.8kHz. The two drivers have essentially 1st order networks though there are other components to shape the response.
Fig 3 – Hawk XT2 Passband
The Black plot in Fig 3 is the crossover passband. See the bump at 2.5kHz. Well, that’s from the L6-4R break-up peak I pointed out earlier. Fortunately, it’s not severe. What this will do is it’ll add slight emphasis at 2.5kHz. Whether it’s audible is another matter.
Fig 4 – Hawk-XT2 Frequency Response
The Hawk-XT2 Frequency Response is in Fig 4. The 2.5kHz bump looks quite harmless. There is a slight depression from 3kHz to 6kHz. Again, that’s tolerable. It would be splendid if it’s flat but without equalization, I’ll have to accept this. This did not originate from the tweeter. It’s from the way the L6-4R is rolling off.
Fig 5 – Hawk-XT2 Null Response
I’m delighted with the Null response of the Hawk-XT2. The null is exactly at the crossover frequency. More than that, it has beautiful symmetry. What it shows is the two drivers are summing properly.
Fig 6 – Hawk-XT2 Step Response
The Step Response (Fig 6) shows a fast take-off in the L6-4R. Apart from the two glitches below 100 microsec, the midwoofer transient is smooth all the way to the apex.
Fig 7 – Hawk-XT2 Waterfall
The Waterfall plot in Fig 7 doesn’t show any anomalies in the treble. In fact, the tweeter exhibits very minimal artifacts. That’s quite an amazing performance for a tweeter that cost about $30.
Fig 8 – Hawk-XT2 Toneburst Energy Storage
The Toneburst plot in Fig 8 shows strong light blue slices from 2kHz to 4kHz. My guess is that they come from the cone break-up of the HiVi L6-4R.
Fig 9 – Hawk-XT2 Spectrogram
In the Spectrogram (Fig 9), the excess energy from 2kHz to 4kHz shows no smearing. They are fully dissipated by 2 msec. Surprisingly, there are two hot spots at 1.2kHz and 1.4kHz. They are the small light blue slices seen at 1kHz in the Toneburst plot. Fortunately, the energy dissipated by 6 msec.
Fig 10 – Hawk-XT2 Harmonic Distortion • RED plot=2nd Harmonics • VIOLET plot=3rd Harmonics
The Hawk-XT2 THD (Fig 10) is about -50dB below the fundamental (Blue plot). It is dominated by the 2nd harmonics in the treble (Red plot). The odd harmonics is about -10dB below the 2nd. This is an unexpected bonus.
Fig 11 – Hawk-XT2 Impedance
The Hawk-XT2 nominal impedance is 4Ω. Nowhere throughout the spectrum did it fall below 4Ω. The protection circuitry in Chip amps will not trigger when they are designed for 4Ω loads.
Sound of Hawk-XT2
It’s refreshing listening to the Hawk-XT2 after working on the Canary-XT2. The “slowness” in the Canary-XT2 is replaced by a much livelier music. This is most apparent in the vocals and the bass. The upper bass in particular exhibits no bloom. Bass sounds tight and is “fast”. No equalization is needed to boost the bass volume. My Hawk-XT2 is in Full Space (4 pi) and the bass volume is just right.
Fig 12 – Hawk-XT2 In-Room Response
Fig 12 is my In-Room response of the Hawk-XT2. Disregard the deep notch at 150Hz. That’s an anomaly caused by a floor bounce in my setup. Notice the region from 100Hz to 65Hz. They are at the same level as the midrange (85dB).
Regarding the slight bump at 2.5kHz, it did not cause any issues. I’m listening to Nana Mouskouri as I’m writing and she sounds perfect. No shrillness, no spitting sibilance, no grating treble. Not many speakers can get pass her singing.
Up next is Elvis “Are You Lonesome Tonight”. His rendition is incredible, albeit the lyrics are a bit too drama for me. Especially the monologue in the middle of the song.
To test out the bass, I put on Santana “Supernatural” album. What I’m listening for is the clarity and attack of the bass. If the bass blooms, it’ll come out a mess.
I’m pleased to say the Hawk-XT2 passed with flying colors. In (Da Le) Yaleo, the bass is distinct and well separated from the midrange. I can even pick up some bass texture in Love of My Life. Quite an achievement for the HiVi L6-4R.
All things considered, the Hawk-XT is a wonderful speaker. It’s doesn’t use expensive drivers yet the sound quality is higher than most. I strongly recommend the Hawk-XT2 for listeners who are conscious of sound quality.
Unless otherwise stated, all measurements were made with the mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied.
November 27, 2020HIFI DRIVERS, Projects