Project – Pentagonal Eikona loudspeaker

Simon Regan’s beautifully-crafted Eikona VTL speakers featured on our blog a few months ago so we were intrigued to see his latest creations. These are a pair of unusually-shaped, floor-standing loudspeakers, based on one of our Eikona MLTL (mass-loaded transmission line) designs. The cabinets have a pentagonal cross-section, designed to reduce internal resonances, and were commissioned by a customer after reading about Simon on our blog.

Simon’s client, George Foster, belongs to the London Live DIY HiFi Circle. He has a history of using Jordan units, having built one of the original Jordan JX92 MLTL designs, and he felt it was a logical next step to try something similar with the Eikona 2.

George experimented with pentagonal cross-section cabinets after hearing the well-known Pentachord speakers in the 1990s. He became convinced that reflective surfaces within enclosures were worth avoiding (something we have achieved with the Eikona Triangular Array).

George says:

“I began with a single Eikona in the 35MLTL enclosure and then added a second driver, in the manner of the DCR. It made an enormous difference – I was surprised at how much fuller the sound became. The next step was to keep the same height but double the volume to 70 litres. Simon and I worked together on the plans, and he showed my wife and I a wide range of veneers. The resulting cabinets are of a much higher quality than my old ones – they look and sound very much better, and our choice of veneer fits beautifully with our living room.

“I was surprised at how much difference Simon’s cabinets made to the sound. I listen to a lot of acoustic modern jazz on vinyl and I have been particularly noticing the improvement in piano sound. The larger cabinets also give an impression of ease – the music seems to float out of them in a way which reminds me of open-baffle designs.”

Simon adds:

”Initially, George wanted me to veneer his existing birch ply cabinets. For various reasons, I suggested that it would be better to make new cabinets. I was convinced that by the time I had worked on the existing cabinets (eg re-machining driver cut-outs and rebating the Eikona 2s), I could have made new ones. I also recommended having veneer on both sides of the board (inside and out) as it balances the wood and avoids warping in centrally-heated homes. George agreed and I was keen to make these look as good as they would sound.

“George and his wife chose birdseye maple veneer, which I selected from Capital Crispin Veneer in East London. Buying it in leaves or strips allowed me to book-match the veneer consistently around the two cabinets. (This is a technique of creating patterns by using two sheets in mirror image to each other like the pages of an open book.) On veneered work, I like to use solid lippings – strips of solid wood – especially on edges which need to be particularly robust or require rounding over. Solid birdseye maple is difficult to find, so I made a trip to Timberline in Tonbridge, a specialist timber yard often used by lute and furniture makers. One thing to note is that birdseye maple can be a challenge to work with since you have to take great care with unpredictable grain direction.

“Apart from the ports, I made sure the cabinets would be completely airtight and very rigid. Inside are a series of pentagonal braces each cut from a single piece of board, then hollowed out and tongue-and-grooved into the sides of the cabinets. Once glued, these added great rigidity and were also helpful when it came to assembly, where I wrapped the cabinet walls around the braces. I used an aerolite glue, which allows the longest time possible to assemble, adjust and clean up the cabinets before the glue sets.

“Prior to gluing, I covered about 70% of the interior of the cabinets in Dedsheet material from Sound Service. As well as adding damping to the cabinet, it added a considerable amount of weight! I attached fine netting to the brace immediately beneath the bottom driver to stop the stuffing (long-haired sheep’s wool) from falling into the lower half of the cabinets. I finished the cabinets in three coats of a clear polyurethane lacquer.  A clear satin finish really looks great on birdseye maple and brings out the detail of the grain.

“It was great to work with George on this project and to hear how and why he came up with the design. It was very satisfying to hear the substantially improved sound and to be part of the process producing this pair of speaker cabinets.”

Simon is happy to work on other Eikona-based loudspeaker commissions. To see more of his work and to contact him direct, visit his website.

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