Birthday Build

Designer:
Rasmus Munk Larsen

Project Category:
Tower Speakers

Project Level:
Intermediate

Project Time:
20+ Hours

Project Cost:
$500 – $1,000

Project Description:
Here is my “Birthday Build” for my friend Mike, commissioned by his wife as a surprise present for his birthday. Mike, our wives and I love to get together to listen to music. Mike is a constant source of learning about cool artists, old and new, for us, so I really wanted to build something excellent that we could enjoy together over the years to come.

Design Goals:
My goal was to create a great sounding and beautiful floor-standing speaker, putting to use all the skill and knowledge I have accumulated over the last few years of building, experimenting, and listening to more experienced speakers designers, here on Parts Express and other online forums.

Driver Selection:
The speaker uses a Vifa XT25BG60-04 1″ Shielded Dual Ring Radiator Tweeter, and a Peerless 830875 6-1/2″ Nomex Cone HDS Woofer. I have used the Vifa XT25 in previous projects and love the very detailed and neutral sound it has. I also think it creates an incredible 3-D soundstage. I had not used the Peerless Nomex cones before, but saw many people recommending them. I am very happy with this choice as it was easy to work with, plays surprisingly deep, and looks great.

Enclosure Design:
The enclosure is a 25 liter bass reflex box tuned to 42 Hz. I simulated it in WinISD.

Enclosure Assembly:
The cabinet has 3 internal window braces, foam dampening (mattress topper) and a 3″ port made from ABS pipe, using a 60 degree knee to make it fit, and flared on the outside using a chamfer bit. The sides of the baffle have a 1/2″ roundover. The cabinet is covered in zebrawood veneer and finished with Polycril.

Crossover Design:
The crossover is adapted almost exactly from a design by Jay a.k.a. Brewski in an old thread here on Parts Express: http://techtalk.parts-express.com/…/45553-hi-i-am-new-and-n…

I used a mix of Audyn and Jantzen (the lower end ones) for the series caps and NPE for the large caps in Zobel and the RLC. Inductors were Jantzen. I added an L-pad (not shown in diagram) consisting of a 3 Ohm resistor in series and an 8 Ohm resistor in parallel to match sensitivity and reduce an upwards tilt of the tweeter response.

Conclusion:
I am very happy with the way these speakers came out, both in terms of looks and finish and sound.

About the Designer:
Rasmus is a computer scientist and amateur choral singer living in the San Francisco Bay Area. He grew up in Denmark (where all those sweet speaker drivers come from).

Project Parts List: