Project Category:
Bookshelf Speakers

Project Level:

Project Time:
8-20 Hours

Project Cost:
$100 – $500

Project Description:
This is a compact speaker with relatively flat response and decent bass extension. My daughter is moving off to college and wanted a pair of speakers to take with her. She asked for something that would not take up much space, but would sound good when playing her music.

The selected color is a bit brighter that might normally be considered for bookshelf speakers.

Design Goals:
The goal was a relatively flat response as far below 100 Hz as possible with a small enclosure.

Driver Selection:
Given the tradeoff of size and ability to move air, I looked for a 6 1/2″ woofer with a good XMax. It ended up a choice between the Dayton DCS165 and the TangBand W6-1139SIF. The DCS has a higher sensitivity and power handling where the TangBand has a bigger Xmax. In the end I went with the Dayton as it was easier to match with the other drivers.

I’ve used the Tymphany BC25SC06-04 before and like the way it sounds. It has a bit of a on-axis bump from 10K-20K and is more sensitive than the other drivers, so it needs a little damping down.

While a 2-way would have been easier, the DCS165 needs to be crossed pretty low to get rid of its tendency to beam in the middle frequencies. The Tymphany can’t go too low, so it was time to dig around for a small midrange to fill in the gap. The Eminence Alpha 4-4 turned out to be just about right for both sensitivity and power handling.

Final selection:

Dayton Audio DCS165-4 6-1/2″ Classic Subwoofer, 295-198
Eminence Alpha 4-4 4″ Full-Range Pair, 290-4010
Tymphany BC25SC06-04 1″ Textile Dome Tweeter, 264-1028

Enclosure Design:
The entire box measures 8 1/2″ W x 12 3/4″ H x 8″ D. Edges are all routed with a 3/4″ round over bit to produce a box with not points or sharp edges to scrape against.

I used a 1 1/2″ diameter chrome tailpiece (any hardware store) cut to length for the vent. While venting at the back limits placement a little bit, it looks better than a deep hole in the front.

A bag of Poly-Fill split evenly between the two speakers worked well.

Enclosure Assembly:
Double Rabbet joints were used for all sides. Wood glue and strap clamps were all that was necessary to assemble the boxes.

Crossover Design:
I modelled a wide variety of crossovers in WinPCD, ranging from 1st through third order. During testing, I found the best balance of complexity versus quality was a very simple mix of: 2nd order on the Woofer to reduce the DCS165’s spike at 2K, 1st order on the midrange and tweeter. There is a resistor inline on the tweeter to bring its response to the same level as the others.

The speakers are performing well. They were drive hard during the course of a graduation party, with a broad range of music. These seem well suited to both Jazz and Rock.

About the Designer:
Built a few different speakers from bookshelf to medium floorstanding. Enjoy the entire process of cabinet construction, driver selection, crossover design, and final measurements and tuning.

Project Parts List:

Dayton Audio DCS165-4 6-1/2″ Classic Subwoofer 4 Ohm  1
Eminence Alpha 4-4 4″ Full-Range Pair 4 Ohm  1
Peerless by Tymphany BC25SC06-04 1″ Textile Dome Tweeter  1
Round Speaker Terminal Cup 2-15/16″ Gold Banana Binding Post  1
Dayton Audio DNR-8.0 8 Ohm 10W Precision Audio Grade Resistor  1

1.0 MH Inductor, Bourns 5258-RC
0.5 MH Inductor, Bourns 5256-RC
100 uF 50G BiPolar Capacitor, Nichicon UES1H101MHM1TO
10 uF 50V BiPolar Capacitor, Nichicon UES1H100MPM1TD

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