5 inch 2-way
13 Liters Bass Reflex Satellite

by Michael Chua

Measurements by LMS version 3.0
LMS is manufactured by LinearX

This design is free for DIY. Not for Commercial Use.
This article may not be published in part or full without the express permission of AmpsLab.

Vifa XT25SC90 + Zaph Audio ZA14W08

The Swift offers exceptional performance at a very reasonable cost. At heart are two outstanding drivers, the ZA14W08 from Zaph Audio and the dimunitive XT25SC90 by Vifa. Judiciously blended by a high order, asymmetric crossover, the Swift sounds so natural it disappears in a room.

It is easier to describe what the Swift is not rather than what it is. On first impression, it does not "Shout" at you. Mids are not excessive, an all too common occurance in Bookshelf speakers. On further listening, you'll discover that there are no dreaded, ear piercing sibilance, no harshness in the upper mids and no grittiness in the highs.

The Swift delicate tonal balance lends itself well to soothing, extended listening. Upper bass is articulate yet non-intrusive. Vocals are clearly focused and cut right through the mix. The highs add just the right amount of timbre and is not overwhelming. No listening fatigue.

With an F3 of 70Hz, the Swift is admittedly a bit shy on bass. For most musical playback, a subwoofer that extends down to 40Hz is recommended for your full listening pleasure.

Gated Crossover Response
No Smoothing Applied
Predicted Low Frequency Response
Bass Reflex (Vb=13L Fb=70Hz)

In Room Response

Departing from the norm of displaying a quasi-anechoic response, the plot on the right is the measurement of the Swift in my untreated listening room. Taken at 1watt/1 meter, Free Space SPL Sweep from 20Hz~20kHz, Smoothed 1/3 octave.

This rather unflattering plot is a more realistic representation of the Swift in actual use. Room boundary reflections are clearly discernible from 100Hz~1kHz. The huge notch at 150Hz is not a defect of the ZA14. It is a null caused by a 150Hz standing wave that's reflected directly back up from the floor beneath.

We can see the effectiveness of the Baffle Step Compensation network in leveling the rising response of the midrange. Without this contouring, frequencies at 500Hz and above will start to climb, culminating in pronounced mids. In our plot, frequencies from 200Hz~1kHz are reasonably flat.

In the critcal region between 1kHz~5kHz, there is a gentle depression. This is desired as this is where our ears are most sensitive. Too much and the mids will sound "bright".

Beyond 5kHz, the rising response is deliberately left uncorrected as high frequencies lose energy very quickly. With the microphone repositioned at 10ft, these highs will level off. Ever wonder why some Flat Response Speakers sound dull at 8~10ft?


next > Swift | Swift-II Hybrid | Swift-II Passive | Swift-II Music
  Swift-III | Swift-IIIa | Swift-IIIb | Swift-IIIc | Swift Ultima
  Swift Ultima-II



Speaker Type  2-way Bass Reflex Satellite
High Frequency Transducer  Vifa XT25SC90-04 Dual Ring Radiator
Low Frequency Transducer  Zaph Audio ZA14W08 5" Midwoofer
Crossover Frequency  3,500Hz
Crossover Network  Butterworth Low Pass (12dB/oct)
   Butterworth High Pass (18dB/oct)
 Frequency Response (+-3dB)  70Hz-40kHz
 Sensitivity (1 watt / 1 meter)  85dB
 Nominal Impedance  6 ohms
 Enclosure Internal Volume  13 Liters
 Enclosure Internal Dimensions (WHD)  7" x 12-1/2" x 9"

Vifa XT25SC90-04 (pdf)
Zaph Audio ZA14W08 (pdf)
ZA14W08 (LMS) T/S Parameters

In-Room Free Space Response

System Impedance

High Order Crossover Network

Enclosure Plans

60 Downes Street | Calais | ME 04619 | USA