Sparrow – SB Acoustics SB13PFC25-08 with HiVi TN28

SB Acoustics SB13PFC25-08 Paper Cone 5″ Mid-woofer

I’ve never used a plastic chassis woofer before so it’ll be interesting to see this SB Acoustics SB13PFC25-08 in action.

After extracting the Thiele and Small Parameters with DATS, I mounted the SB13 onto a 7 liters bass reflex box. My intention is to determine how much bass this fairly small woofer is capable of producing.

SB13PFC25-08 Raw Frequency Response


Fig 1 – SB13PFC25-08 RAW Frequency Response in 7L bass reflex box

Disregard the deep notch at 150Hz. It’s caused by a “floor bounce”

The Black plot in Fig 1 is the RAW response of the SB13PFC25. Disregard the deep notch at 150Hz. It is caused by a “floor bounce”.

After listening to the SB13PFC25 in it’s raw state, I shaped the low pass filter in such a way it won’t lose the bass when it crosses over to a tweeter. Otherwise, the tonal characteristics of this midwoofer would change.

Sparrow Frequency Response


Fig 2 – Sparrow Frequency Response

The Black plot in Fig 2 is the Sparrow’s Frequency Response. When you compare the two Black plots in Fig 1 and 2, you’ll see they are very similar up to 4kHz. Beyond that, the HiVi TN28, sitting on top of the box, takes over for treble duty.


Fig 3 – Sparrow Frequency Response with TN28 wired in Reversed Phase

The Violet plot in Fig 3 is the Sparrow’s Frequency Response with HiVi TN28 wired in Reversed Phase. This resulted in a deep notch where the SB13PFC25 crosses with the TN28. A notch of this nature is a good indication that the two drivers are crossing properly.

the Sound of the Sparrow

The Sparrow shines in the bass. Unlike the Zaph ZA14W-08 and many other 5″ midwoofers, the Sparrow’s bass is as loud as the mids and highs. This contributes to it’s excellent tonal balance.

But it’s more than simply bass loudness. It has one of the finest bass character that I’ve come across. Bass is punchy yet tight. In engineering terms, it’s known as “fast attack” and “minimal ringing”.

The Sparrow is great for Classical, Vocals as well as Jazz music. Double bass notes are clear and defined. Voices cut through the music and the cymbals are not harsh. 

With a volume of only 7 liters, the Sparrow is well suited for places where space is a premium. Be it your home, office or business premises like restaurants, fashion boutiques, etc, the Sparrow will deliver high quality, soothing music. All from a plastic frame SB13PFC25-08 midwoofer. Unbelievable.