Swift-II  (HD)
(High Definition Series)

5 inch 2-way
13 Liters Bass Reflex Satellite

by Michael Chua

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This article may not be published in part or full without the express permission of AmpsLab.

ZA14 with Passive Network


Fig 8 - ZA14 Response with Passive Crossover (Blue trace)

The Blue trace in Fig 8 is the acoustic response of the ZA14 with a 3rd order network. The network has been adjusted to follow closely the acoustic properties of the ZA14 Hybrid Response (Red trace) shown in Fig 3.

XT25SC90 with Passive Network


Fig 9 - XT25SC90 Response with Passive Crossover (Blue trace)

The Blue trace in Fig 9 is the acoustic response of the XT25SC90 with a 3rd order network. The network has been adjusted to follow closely the acoustic properties of the XT25 Response (Red trace) shown in Fig 4.

Frequency Response of Swift-II with Passive Crossover


Fig 10 - Frequency Response of SWIFT-II with Passive Crossover ( 2.25kHz | 18dB/oct)

Fig 10 above shows the summed response of the ZA14 and the XT25 with a full passive crossover. Acoustically, the ZA14 and the XT25 cross at about 2.25kHz. There is a slight dip in the response from 1.5kHz to 3.5kHz. I left this uncorrected as our hearing is most sensitive in this region.

Fig 11 below are the plots of the Swift-II with the XT25 connected In-Phase (Blue trace) and connected in Reversed Phase (Black trace). The symmetry and depth of the notch at the crossover point are indicative of proper acoustic summation.

In-Phase and Reversed-Phase Responses


Fig 11 - SWIFT-II InPhase and Reversed Phase Summing

 

Swift-II Passive Network


Fig 12 - SWIFT-II Passive Network (18dB/oct)

The crossover components are shown in Fig 12. Recommended types are Polypropylene Capacitors, Air-Core Inductors (minimum 18 awg) and preferably Non-Inductive 10 Watts resistors. To save cost, the 50uF can be a Non-Polar Electrolytic Capacitor.

Fig 13 is the impedance of the Swift-II. The lowest impedance is about 3.5 ohms at 3.0kHz. This correlates to the Re of the XT25SC90. The Swift-II should be matched with a power amplifier rated for 4 ohms Nominal loads.

Swift-II Passive Network Impedance


Fig 13 - SWIFT-II Impedance (18dB/oct)

 

Swift-II Box Modelling


Fig 14 - SWIFT-II Simulated Box Tuning (13 Liters Bass Reflex)

The Swift-II prototype box is 13 Liters Internal Volume, tuned for Fb= 54Hz with a 2" Diameter PVC tube of Length 5". Fig 14 shows the simulated box tuning.

I opted for a slightly larger box with a F3 of 47Hz. In the event if the Swift-II is used without a Subwoofer, the lower F3 will come in handy.

Sound of Swift-II

How does the Swift-II sound like? If you're fortunate enough to own the renowned AKG K240DF, the headphones that are the mainstay in Recording Studios, Swift-II sounds remarkably similar. It is neutral, transparent and revealing. Excellent for Nearfield Monitoring use.

 

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

 


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