Lewis Stand Mount Loudspeaker
Description of this page
The Lewis Standmount Loudspeaker is a compact two way bass reflex standmount loudspeaker,
This loudspeaker began life as a collection of spare bits left over from the disassembly of other speaker sets. The cabinets were already built for another unfinished project. The internal cabinet dimensions were 250mm high, 185mm wide and 215mm deep. Note wall thickness adds to the external dimensions. I tried the woofers in the cabinet and was pleased with the performance, so I decided to create a complete speaker system.
The cabinet is about 10 litres volume. No attempt was made to match the drivers Thiele/Small parameters to the case. The baffle is a piece of 18mm pine, with the speaker mounting holes cut using a router circle cutter. The baffle and the bare cabinet walls had no veneer applied and were rubbed down to be stained a convenient brown colour. The bass driver was sealed with speaker sealant (Jaycar CF-2762) to prevent leakage, while the tweeter was intimately mounted on the flat cutout produced by a circle cutting router, with the notches for the tweeter terminals cut by a jigsaw.
The bass driver is a no name 6.5" Chinese driver with a medium sized magnet and a cloth semicircular suspension. The cone was doped with Aquadhere PVA to improve the midrange performance. The tweeter is an inexpensive Jaycar CT-2005 25mm 20W Dome. The crossover network is a 12dB/octave Linkwitz-Riley at about 3500Hz, with driver voice coil impedence correction. The network was built on a Jaycar CX-2605 Crossover PCB with Jaycar PT-3006 speaker terminals.
The crossover network is placed on the back of the enclosure, mounted on two wooden rails, which spaces the underneath soldered joints away from the internal wall and adds rigidity to the enclosure. Note the solidity of the cabling between the crossover and drivers. The cabinet was then lined with insulwool and stained.
The speaker was finished with the application of a grille and grille cloth. The grille is a 1/4" fibre board sheet, cut out with circular holes for each driver and close mounted to the baffle on four speaker grille clips (Jaycar CF-2761). The grille cloth (Jaycar CF-2752) is acoustically transparent and glued plus stapled to the rear of the grille.
They would be ideal for their intended use of filling a small lounge room in a flat with rock music. Without having a deep bass, they are capable speakers without the thumping performance that annoys neighbours. The speaker was given as a present to my nephew Lewis, along with a Sony 80w/chan 5.1 channel tuner amp and a CD player. I hope he looks after them and appreciates the work that went into building them.
Circuit for the Crossover Network