
Markaudio’s Alpair 5 Copper-Gold Teams Up With CSS’s SDX7 Woofer
Combining the Alpair 5 Copper Gold with the SDX7 presents system builders with a great opportunity to have possibly one of the best 2 way speaker combinations currently available. The Alpair 5’s clarity and detail matched with the SDX’7 powerful tight bass, together delivers superb music reproduction. System builders have a very wide choice of crossover points, anywhere from 150Hz to 5000kHz depending on personal preferences and box designs.
Build Recommendations
- Internal Height: 25cm
- Internal Width: 40cm
- Internal Depth: 16cm
- Internal sealed compartment for Alpair 5 driver: 0.6~1.0 litres.
- Port internal diameter: 2.54cm
- Port length: 4.5cm
- Port location: Position port with minimum 3cm clearance from internal enclosure base.
- The Alpair 5 and SDX7 can be placed in any location for personal preference. We recommend the Alpair 5 be fitted into a sealed compartment at the top with the SDX7 in the lower part of the enclosure.
- Material thickness recommendation: MDF board 15mm to 20mm, natural soft woods 20mm, natural hard woods 15mm.
- Damping material recommendation: 25mm thick open cell low-density foam, low-density wool and similar fibres.
Here is a 15-litre size enclosure using the classic ported box design:
These dimensions are a guide and can be varied up to 15 % in box volume for suit personal taste.

Crossover
The crossover point can be very wide (from 200Hz to 5000kHz) giving much personal choice. We suggest crossing over at around 1000Hz using a simple 1st order crossover. The circuit is included in our line drawing.
- Crossover point: 1000Hz
- Resistor recommendation: A resistor will help balance the load between the Alpair 5 and the SDX7. We suggest a 10 watt wire wound type with a value of 4 to 6 ohms.
- Capacitor recommendation: Use a good quality audio cap, values between 100v to 250v and 20.0 uF.
- Inductor recommendation: Use a genuine good quality iron or steel core inductor with an ultra-low DCR with a value around 1.0 to mH.
Please Note
These figures are to use as a guide. It is recommended that system builders do sufficient research to be satisfied with their design. Box dimensions, port size/length and position and crossover points can be varied to suit personal tastes. Have fun and enjoy the music!