Good progress since last post – both woofer boxes now glued and screwed. The process was not without incident, but no major glitches. I was glad I had invested in some aluminium sash clamps, although soon found myself wishing I had ordered six rather than four.

I knew that order of assembly was important from thinking about this as well as perusing other audiophiles’ build logs (notably Bill Schneider’s meticulous record). Using dowels to strengthen the joints between the V-frame and the sides makes assembly order critical, as all V-frame elements have to be assembled and glued before lowering these onto the side dowels. The photos show the order I adopted.

When assembling the first box I discovered (after priming dowel holes with glue!) that the slightly proud through-dowels between the upper V-frame and the small filler behind the front flap prevented me from dropping the V-frame assembly in place! – I had anticipated sufficient play to allow this, but no…

Some rapid planing off of the protruding dowel ends rectified the problem.  This apart,assembly proceeded uneventfully.

 

 

 

 

 

 

 

 

 

 

 

 

I used waxed discs (as used for preserves) to confine the Evostick to the joint being glued during the staged assembly; another good idea from Bill Schneider.

 

 

 

The dowel-glued V-frame assembly, shown separately here, felt extremely strong with minimal give – I was glad I had decided to glue it in place using the side dowels to ensure correct alignment. Its stiffness was what led to my protruding dowel problem!

 

 

 

This shows the underside of the front flap and mitred filler piece; I used screws here (impossible to clamp), and I won’t be filling these in their concealed position.

 

 

 

The boxes came together reasonably well and square; the 2″ x 8 screws countersunk into the sides pulled the V-frame side joints nice and tight.

 

 

 

Some planing was needed to top and bottom to bring sides flush before final sanding. I did have to fill the front flap on one box as the lower edge ended up a millimetre displaced backwards. I spot primed these areas together with all countersinking and other minor surface defects before filling.

 

I had researched wood fillers before commencing the build, and had settled on Toupret TX110 filler (the French like to finish stuff properly). It needs a few hours to develop full strength but it cures very solidly and sands beautifully flat thereafter – a good buy. Filling and sanding the countersinking on the sides and bottom completed the making good.

I am impatient to get on with the gluing up, however the advancing years have happily brought reserves of patience I  was certainly not in touch with as a younger man. Preparation, preparation! I sanded down all the flat surfaces today, using 80G, then 120G – the nooks and crannies in the completed woofer boxes make this nigh impossible after assembly.

 

I was pleased that I remembered to drill holes in the upper V frame to take the upper woofer wires through to the rear.

 

 

 

 

 

 

 

Last job of the day was spot priming various surface imperfections (and my unintentional through-holes) prior to filling tomorrow. I have decided to make life easy for myself by going the acrylic route, and I’m using Bedec grey primer. I’ve also bought tins of Bedec matt black and satin black top coat as I don’t know which will look best – I can use the same stuff for the tweeter baffles later.

A few photos of construction details.

Apart from those anchoring the V-frames to the sides, screws were used only in hidden areas, namely the filler behind the front flap and the lower V-frame joint with the bottom.

 

 

Drilling dowels for the upper V-frame mitre joint.

 

 

 

Setting out V-frame and bottom mitre joint. I drilled a 5-dowel joint between upper and lower V-frame elements.

 

 

 

Fitting “top” side before marking out V-frame dowel positions.

 

 

 

Squaring across marks and centring at 9mm.

This is my build log of Siegfried Linkwitz’s latest and best open baffle dipole loudspeaker design – the LX521.4.

My relationship with SL’s designs goes back a fair way… my good friend Pete Johnson at medical school drew my attention to Siegfried’s Wireless World active crossover system some 30 years or more ago – we both decided to build one. Pete was a whizz at electronics, whereas I was more comfortable working with wood (thanks, Dad!). Last year for some reason I found myself wondering whether Siegfried was still alive and active in the audio field and searched out his website . It did not take me long to decide to build the LX521s – my old WW system had fallen into disrepair and had been consigned to the garage years earlier (I have renovated it since – separate page to follow).

I hope the log will both inspire and help others to build their own LX521s. I’ve not even heard them yet! – but everything I have read suggests I won’t be disappointed when they are finally up and running.

Click on any thumbnail to see full photos.