“Bella is Italian for beautiful, Sonus is Latin for sound. Magnifica is Italian for magnificent. This project embodies all of the best design language cues I have developed for my Bella Sonus models. It is my best work to date.”

“Bella Sonus Magnifica #24” Tower Speakers, by Michael C Hadjinian

Project Level: Advanced

Project Time: 20+ Hours

Project Cost: Over $2,500

Project Description: The cabinet design is a tall, slender 3-way design with dual woofers. The main body has a 5-degree slope back. The top is tilted forward to 14 degrees and the tweeter and mid cabinet section have a bump out so they point directly at the seated listening position.

The cabinet design follows my Bella Sonus design language – this consists of these elements:

1st the beautiful natural walnut wood with contrasting black front and body. Note the 4” horizontal grain walnut and contrasting color narrow divider strips. It has a black Naugahyde faux leather front. This gives it a rich natural materials look.

2nd the shape – it has a hexagonal cross section that mimics the curved lute shape of many high-end designs. I designed a chevron wood grain pattern on the top to give the speaker the emotion of flowing through the surrounding space.

3nd 5-degree slant back – this design is purportedly used to help acoustic alignment. I thought this was mostly BS. As mentioned, I added the bump out to point the mid and tweeter directly at the listening position. I made the acoustic offset calculations using REW and amazingly, I only needed to make a 3/8″ acoustic offset adjustment in my crossover. I double checked my work because it felt like too much of a coincidence. So, the tilt back looks cool and it works!

The main benefits of this cabinet design:

1st – It is very rigid, due to the hexagonal shape, there are no wide panels that easily resonate and no parallel walls that reflect sound.

2nd I have perfected building this shape over the past 4 years and based on my accumulated experience, I have all the angles down. I can build it efficiently with templates and a track saw. It is now a very doable DIY design for me.

3rd The design is versatile. I have made several variations: wider, narrower, shorter and taller, 2 and 3-way, tall tower to a small stand mount bookcase, a flat top and an angled top.

Finally – It looks beautiful, similar to a Sonus faber and Focal high end look but still with its own unique characteristics

“Just FYI, my out of pocket costs were $2500. My labor is priceless enjoyment.“

Design Goals:  have two design goals for this project:

First, I want a speaker that is beautiful, goes with any room’s décor and is of a manageable size. The cabinet is 52” tall and front panel is 8.5” wide. It weighs of 96 lbs so that it can be moved around relatively easily.

Second, I wanted a superb sounding speaker the heart of which is the crossover. My goal was a very smooth crossover, 35-20,000 Hz, with a gentle Harman curve.

Driver Selection: Let me start with the unconventional midrange. It is the Morel 1308 which is a 2 1/8” soft dome. It is highly rated and I was eager to try it out. As a midrange, it does much of the heavy lifting for sound-stage and I feel it delivers excellent midrange performance. I detected no issues even though it is a soft done. It is rated for 1,000-10,000Hz. I have it crossed at 1300 Hz and 3700 Hz. This is the most expensive driver in this setup.

The tweeter is the Morel CAT 308. It is a classic soft dome. It has earned a great reputation as a very fast tweeter capable of high dynamic range. It pairs nicely with the mid.

The woofers are the Wavecor WF182BD17 7″ Black Coated Paper/Glass Fiber Cone Midwoofers. I am delighted with them, this first time I have used Wavecor. They are reportedly designed by former Vifa/Scan-Speak engineers.

I added a rear ambiance tweeter with an adjustable L-Pad. It is the Dayton Audio CF18 3/4″ Carbon Fiber Neodymium Dome Tweeter. Several high-end designs incorporate this technique to add detail to the sound-stage, I can point out vintage designs from Infinity and Snell and modern designs from PS Audio, Vandersteen, and Von Schweikert.

Enclosure Design: The front and horizontal panels are Baltic birch. The 4 sides and rear of the cabinet are MDF. The front and back are covered with Naugahyde. Nice look and feel.

Sides are 4” walnut horizontal grain, dark bottom to light top color, with 3/8” rosewood dividers, 3 coats of a clear natural finish wipe on poly and fine paste wax

The top has an additional ½” thick walnut wood panel with a chevron grain pattern.

Finally, I designed and built a very solid looking walnut base. There is a tapered spacer between the cabinet and the base that provides a floating appearance. The base anchors the cabinet visually and has been added to my design language. The wide spacing of the legs provides ample stability for the tall narrow cabinet. There are 4 easily adjustable feet.

I worked with a CAD designer experienced in Solid Works to develop renderings from my sketches. We perfected the design after a few iterations. Then detail drawings were prepared. I developed templates from 1/8″ paneling and then cut the parts with my track saw. There were many miter angles. The shape is its own fixture.

Crossover Design: This project has the most refined crossover I have designed so far. It started out complex but eventually I developed a simpler crossover where the final component count was much more modest. The woofer and tweeters are second order. The midrange is a third order with steeper slopes to stay within the range of the Morel 1308.

I did the full REW and XSIM DIY software program, calculating impulse gates, baffle step correction and acoustic offsets. I used WinISD for the port design.

Amazingly, all the software calculations worked as they were supposed to. I did some very minor tweaking of resistors by ear.

Note the speaker has a rear ambiance tweeter with an L-pad to adjust to suit the room. It is a Dayton CF18N high tech carbon and neo design.

“Turned out very well. They were not perfect, but sound very good – just need more time to break in.”

This is my 5th year in the DIY hobby, and I continue to be amazed at how much there still is to learn. It is an intellectually stimulating hobby that allows me to work with my head and my hands. I started my formal education as an engineer, and I love doing this kind of work again.

The hobby also enables me to critically listen to and enjoy music.

The hobby is a combination of industrial design, aesthetic design, acoustics, CAD design and rendering, computer design and simulation, testing techniques, electrical circuit design and electrical engineering, mechanical engineering and wood working, plus it allows me to equip my workshop with many kinds of modern tools. I love tools.