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3WHE stands for "3-way high efficiency". This speaker is my attempt at my holy grail - a small bookshelf speader with deep bass extension and high efficiency at a reasonable cost. To accomplish this requires just the right woofer and I found it. The secret sauce to making this speaker work is the Lavoce WAF061.80 6.5 inch woofer. When modeled, I got some really impressively small vented boxes - almost too good to be true. I ordered 2 from Parts Express. They arrived nicely packed in a cardboard box. These are superbly made and very heavy for there size. Mounted on a test baffle and measuring in-room, they looked like the real deal.

Usually for a woofer of this size, a 2-way would do the trick. But I already had a pair of Dynaudio D52 soft dome mids looking for a home. These are high sensitivity mids that would keep up with the Lavoce woofers. To round out the high end, I used a pair of Foster ET100 ribbon. Together, this had the making of a really nice 3-way. Here are PDFs for each of the drivers used:

Since the box is going to be relatively small, I wanted to minimize the front baffle size. The size of the woofer dictated the width of the baffle. The 5.5 inch long port influenced the minimum depth of the box. The height was a function of all the drivers and 2 inch port diameter. Box and port modeling showed that the port length was not very critical - the net effect on the F3 point varied minimally with port and box size so I ended up with a box that made sense based partly on the materials I had on-hand. The front baffle is 2 layers of MDF - 3/4 and 1/2. The 1/2 inch allowed me to recess mount the woofer which a 1/2 inch thick flange. The mid and tweeter are flush mounted to the baffle. The other 5 sides are 3/4 inch MDF. Where it mattered, I took the time to cut perfect circles with a jig; otherwise the circles were cut with a jigsaw.

The tweeter required a little extra work. The shape of the tweeter is unusual and it would be difficult to cut an opening in MDF for a snug fit. I therefore asked my son to create an adapter that would convert the tweeter's irregular shape into a standard round fitting. The adapter was 3D printed and worked like a charm.

The crossover is really simple. Simple is nice if you can get away with it. The tweeter has a single 3uF cap for the high filter. The mid has a single 30uF (3 x 10uF) cap for a high pass. There's no low pass - the D52 is so well behaved I just let it run open on the high end. The woofer has a second order 10uF cap and 2.5mH inductor for a LP. The components are zip-tied and caulked to a piece of polycarbonate which is screwed to the bottom of the case.

For visual appeal, I painted the baffle black and made the grill from plywood and black acoustic fabric.

The cabinet is veneered with zebrawood - bookmatched down the center and then dyed orange and top coated with a semi-gloss urethane.

This is very much a bookshelf speaker. Placed against a wall, the sound is authoratative in the bass, smooth in the vocals and not tiring in the highs. They are efficient and fill the room effortlessly. Overall, I'm extremely happy with these speakers on all levels.

21-October-2023

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