Homemade spherical columns with your own hands from chipboard

Let me share the joy of long creation! Spherical columns with a diameter of 50 cm were made.The wall thickness was 3 cm. Internal volume – 50 liters. VRC-200 speakers, 8 “coaxial type with a silk beeper on the magnet core. The phase inverter is directed downward into the ring of the stand. Made from a piece of plastic pipe.

The dream of making round columns came to me a long time ago, in the early 80s. Inspired by the brochures of the company Grundig, which produced spherical speakers. Now I have not found a single mention of these glorious products on their website. I will not delve into the advantages or disadvantages of the ball shape here. This is a huge and separate topic. The technological goal is to tell about how it was done on the knee and in the kitchen.

20 years ago, I never came up with an acceptable way to implement the idea. There was an attempt to glue it from papier-mâché. A children’s inflatable ball with a volume of ~ 16 liters was pasted over with pieces of newspaper. After a month (!) Of gluing, it was possible to achieve a crust thickness of 10 mm. After all, each layer had to be dried! Then he safely migrated to the trash heap – the volume is too small and the walls are thin.

But thanks to Genn (see 2 *), who in his article suggested an interesting technology, and the idea came to make balls from typesetting rings of chipboard. I chose the thickness of the chipboard 16 mm and calculated a set of rings. The material was purchased at first for one column. After all, I did not know what would happen, and whether it would work at all. I had to buy a stack of 50x50x50 chipboard squares.

As a result, waste was generated, some of which was later used for the second copy. As a result, the second column took 2 times less material than the first. First, the discs were marked and sawn out with a jigsaw. Holes were drilled in the center of the discs for the subsequent centering of the ball. All discs, of course, were numbered.

The discs were screwed together. Then the inner diameters were disassembled and sawn off.

The rings were glued with pink PVA-based wood glue. He keeps it tight. After lubricating the ring with glue, it was screwed into the marked holes. This ensured correct alignment. The result was a ball with a stepped surface.

The step was leveled with a large rasp, which literally crumbled the excess material. Oddly enough, this stage went quite smoothly and evenly. The excess was simply mowed, and it is not so easy to slaughter in the unnecessary direction. The rasp just bumps into a wall.

I used a thick cardboard template to control the shape. Any irregularities and scratches were putty with wood filler. Final finishing – sandpaper.

After getting the shape and surface in proper shape, I soaked the ball with primer.

The bass reflex hole is located at the bottom of the speaker. Then the question arose with the external design. Various options were considered – veneer covering, painting. There was even an interesting idea of ​​pasting with yellow and red leaves. A kind of herbarium 🙂 Ultimately, I used the simplest and, at the same time (for my taste), good looking solution – liquid wallpaper.

The stand for spherical speakers is made on the basis of former stools, the legs of which are made in the form of a dovetail. A chipboard ring is screwed on top, surrounded by a golden nut. Now I myself do not like these coasters very much, and a more interesting solution is being sought. I would like to do something like a chess piece leg with a heavy base. For example, a pancake from a barbell.

The bass reflex tube was tuned to a frequency of 40 hertz. I am not a fan of high order filters, so the filter is inside the first order. Just the capacity of the MBHP for the buzzer. The walls inside are stepped and covered with foam rubber. The resonance of the sphere without phase inverter is about 60 Hz. The phase inverter was tuned mainly by ear. Now about the sound. I believe that my expectations were fully met. It was a lot of work, but it was worth it. I really like the sound. Much depends, of course, on the amplifier.

The sparring partner of the balls is a 50-watt push-pull tube amplifier. The mids sound especially good, but the bass is impressive too. The speakers, in my opinion, are just perfect for classical music. I also (and mostly) listen to rock on them.

Pink Floyd “Wish you were here”, for example, is just a test disc. The room certainly needs some harsh acoustic rework. The decor is spartan and bachelor. So, I’m sorry ..

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Source: from here