Hawk – HiVi L6-4R with Peerless XT25TG30-04

How the Hawk came about

I liked what I heard during the auditioning of the L6-4R in an active bi-amped system. I believed that I finally found a woofer that I can design a 2-way bookshelf speaker that has sufficient bass, a clear midrange and treble that doesn’t assault you. And most importantly, I can achieve this without having to resort to any correction networks. No BSC, Zobel and LCR. Just a High Pass and Low Pass.

Hawk Frequency Response


Fig 1 – Hawk Frequency Response. Mic at 1m, tweeter axis, 1/12th octave smoothing

After testing different crossover iteration and much auditioning, I settled on the response in Fig 1. The Black plot is the summed response of the Hawk. It is fairly flat from 500Hz to 10kHz. The Blue plot is of the L6-4R and the Red is of the XT25TG30-04.

What is interesting with this crossover is the tweeter’s response. Note the absence of Baffle Edge Diffraction. And this response is with my test box with sharp edges on all sides. Furthermore, the XT25TG30 is not flushed mounted.

Hawk Harmonic Distortion


Fig 2 – Hawk Harmonic Distortion. Mic at 1m, tweeter axis, 1/12th octave smoothing

Disregard the notch at 150Hz in Fig 2. It is caused by floor bounce. I can assure you that there’s bass with this speaker.

Overall Harmonic Distortion is -50dB below the fundamental all the way up to 10kHz. In percentage terms, it’s about 0.3%.

The purpose of this measurement is not for the speaker to display the lowest distortion. Rather, if it registers high distortion, it tells me that something is not right. Perhaps some manufacturing defects with the drivers.

Hawk Impedance


Fig 3 – Hawk Impedance Sweep

Fig 3 is the Impedance Sweep of the Hawk. Some solid state power amplifier’s protection circuits may be activated due to Hawk’s impedance.

It barely touches 4 ohms at 200Hz, which is expected from a 4 ohms woofer. What power amplifiers really dislike is at 10kHz. Here, it dips to 3 ohms. Fortunately, there’s not much energy up there. Owners of tube power amps may not face this issue because some output transformers have 2 ohm tap.

Though the impedance may be demanding at 200Hz and 10kHz, the Hawk’s Phase Response is quite friendly. From 200Hz to 20kHz, it is within a +/- 35° window. This helps to lighten the load on the amplifier, in particular at 200Hz and 10kHz.

How does the Hawk sound like

Wonderful. It came out exactly what I had hoped for. It is very musical. Strong mid-bass, vocals that don’t shout at you and treble that doesn’t screech. All in a compact 13 liter box.

Surprisingly, the Hawk reproduces instruments rich in details. It sounds like the band is right in front of you.

Crossover Values & Box Dimensions

If you’re interested to build this project, kindly send me a mail for the crossover component values and box dimensions.