Designer:
David Hancock

Project Category:
Bookshelf Speakers

Project Level:
Intermediate

Project Time:
8-20 Hours

Project Cost:
$500 – $1,000

Project Description:
I have built a number of speakers over the last 15 years some kits, some other peoples designs and a number of my own designs. These “bookshelf” speakers are a three way design with a front port due to placement.

Design Goals:
I was limited to a specific size due to planned placement of the speakers and they needed to be placed against the wall on a shelf. I opted for a front port for this reason. The use of the speakers is a variety of music powered by some vintage gear. They needed to be a specific height, depth, and width, so I had to work within those specific parameters. I also wanted them to look a bit vintage so I used a walnut veneer and some grills Part #260-346 and grill cloth Part #260-335.

Driver Selection:
The Dayton RS180-4 Part #295-374 woofer was chosen for the cabinet size and the bass requirements.
The Dayton RS100-8 Part #295-352 mid was partially chosen for aesthetic reasons but also modeled very well in the intended range.
The tweeter was a little more difficult to choose. I initially wanted to use the Dayton RS28F-4, but this didn’t quite fit the budget. I chose the Dayton ND25FA-4 tweeter Part #275-059. It modeled well with the other drivers selected and fit the price point.

Enclosure Design:
Within the size limitations I chose the largest woofer I could to provide the wanted bass response. The enclosure size minus the space required for the mid enclosure and port worked out to roughly .72 cu. ft. for an f3 of 37 Hz. The port is a 2″ Precision Port Part # 268-348 at 7″ in length. I was in the process of designing the mid enclosure when I remembered that years ago I built a boom box for my daughter and happened to have a couple of PVC end caps on hand. I utilized these for mid enclosures for her boom box and nearly 10 years later they are still working just fine. So I used a 3″ ID PVC end cap glued to the front baffle to enclose the mids. I offset the PVC end cap on the mid to get the tweeter mounted as closely as possible to the mid.

The layout of the drivers was a challenge as I needed to fit the woofer, mid, tweeter and the flared port on the baffle. The height limitation of the enclosure forced me to mount the mid and tweeter horizontally offset from the woofer. This worked out fairly well as I was most concerned with the distance between the mid and tweeter. I was able to fit the port between the woofer and the mid and tweeter.

Enclosure Assembly:
The enclosure is a simple box with 3/4 inch MDF and a PSA Walnut veneer. All the drivers are flush mounted.

Crossover Design:
The woofer has a 2nd order, the mid is 2nd order on both ends and a 3rd order on the tweeter. Crossover points are at roughly 300Hz and 3500Hz. The lowest impedance is at 4 ohms but mostly 6 ohm.

Tips & Tricks:
I  would have to say that using the PVC end cap as an enclosure for the mid was so simple. And since the thickness of the PVC is thinner than I would have used with MDF it takes up less internal volume in the enclosure.

Conclusion:
This was a really fun build and they really met the desired goals of the build. The criteria were very strict regarding size and placement which was a challenge. They really sound fantastic and was really happy with the outcome.

About the Designer:
I am a computer security professional, trombone player, and hobbyist speaker builder.

Project Parts List: