Trapezoidal Onken Speakers for Fostex FE103Sol

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Project by jdrouin posted 09-03-2021 04:51 PM 682 views 1 time favorited 7 comments Add to Favorites Watch

Not long ago, I completed a pair of trapezoidal Onken enclosures for the Fostex FE103Sol 4” single full-range driver. The white cones are made of banana! These speakers live in my small home office. The design is by David Dlugos at Planet 10 Hi-Fi in Victoria, BC, Canada. Panels are made from 15mm Baltic birch plywood for optimal acoustics and architectural stability. I alternated the vent spacers between Brazilian cherry (jatoba) and white oak for a 3-wood/3-color visual effect. It was difficult to find a nice way to finish the Baltic birch because of the splotchiness. After much testing on scrap, I ended up using coffee as a light stain—I literally brewed a pot of Trader Joe’s French Roast and put it on the wood—which soaked in evenly with a foam brush (six coats) and gave it a nice character (and smell!). Two coats of Minwax satin polyurethane top it off for a subtle sheen and protection. The interior walls are lined with 100% natural wool batting.

The sound is remarkably full, detailed, and dynamic, with a gorgeous reproduction of tonality that conveys the emotion of the music. And all this despite their somewhat diminutive size of roughly 12” H x 7.5” W x 9” D.

7 comments so far

View splintergroup's profile


5843 posts in 2460 days

#1 posted 09-03-2021 09:16 PM

I had to read up on these drivers, quite the following!

Where did you find the bare drivers?

Looks really cool!

View HerringImpaired's profile


105 posts in 947 days

#2 posted 09-03-2021 09:21 PM

Nice! They look like they would be a great speaker for when you don’t have a wall behind them…..

-- "My greatest fear is that upon my demise, my wife will sell my tools for what I said I paid for them."

View jdrouin's profile


12 posts in 618 days

#3 posted 09-03-2021 09:22 PM

splintergroup: They really are excellent. I got one of the last pairs from a Canadian retailer a few years ago, I think or Creative Sound Solutions. eBay,,,, and other used places are probably your best bets at finding a pair. There’s also the meta search engine, where you can search multiple sites at once and also set up an agent that will automatically notify you when any go on sale.

View jdrouin's profile


12 posts in 618 days

#4 posted 09-03-2021 09:24 PM

HerringImpaired: Thanks! They are best in a small room. In my home office they sound optimal with about two feet of distance between the back of the speaker and the wall.

View swirt's profile


6618 posts in 4209 days

#5 posted 09-04-2021 12:50 AM

Those look as cool as they probably sound. It’s an interesting design.

-- Galootish log blog,

View oldrivers's profile


2725 posts in 2804 days

#6 posted 09-04-2021 03:07 AM

Good job.

-- Soli Deo gloria!

View RespiratoryFailure's profile


13 posts in 454 days

#7 posted 09-22-2021 04:04 AM

I would never consider using coffee for a stain, absolutely brilliant!!!! Great speakers!

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