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Wolf

"W3-517S1-DCR" writeup....

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“W3-517S1 DCR” by Ben “Wolf” Shaffer 5/27/07

I took these to Dayton DIY 05/06. What a positive response they received!

Design Goals:

This was my first attempt at a one-way single-driver full-range project. I picked up this pair of drivers from the first annual Parts Express Tent Sale for about $3 total. I later learned that these are in high demand for commercial companies due to the great off-axis response characteristics, and that I may own the only pair in the lower 48 states. I wanted to give these drivers the best home I could, and pray that their performance was top notch.

Driver Selection:

The driver in question is the Tang Band W3-517S1. This is an odd looking driver to some people, but others see something different and unique. I wish Parts Express stocked these, as I would be buying a few more of them. It comes from the factory with a lathe turned wooden phase plug made from a native hardwood. The features consist of a paper cone, cast aluminum frame, under hung voice coil, rubber surround, and shielded magnet structure. Xmax is a small .5 mm, and power handling is a good 15 watts.

Enclosure Design/Assembly:

I did not know the specifications of the units, and had not a measurement system at the time to measure them correctly. I enlisted the help of Al Wooley at Raw Acoustics in Canada to point me in the right direction. He informed me of the driver’s parameters, and also gave me a set of box dimensions to use. This involved a cabinet made with ¾” thick material, the internal dimensions of 7.5”H x 6.5”W x 7.25”D, and a single 1” diameter hole that was ¾” long (or the thickness of the baffle). I took this cabinet design and altered it to try a different approach to a vented alignment. I went with a dual-chamber-reflex (DCR) design, by splitting the 1” hole in half to either side of a ¾” thick internal partition. This gave me the 2 equal outer semicircular ports, and I placed a single semicircular port in the edge of the internal partition to link the 2 chambers. This port is of the same dimension as the other external ports. The cabinet is divided into 2/3 and 1/3 volume respectively, with the driver in the larger volume, and both sections lightly stuffed with Dacron. The cabinet is painted with Duplicolor truck bed liner on all internal walls, and the driver cutout is scalloped from the backside to allow better breathing room. The front and rear vertical edges are rounded, as well as the front top edge. This helps minimize diffraction.

The partition has a tongue that protrudes through the front baffle to separate the 2 ports, and provide an alignment point for the removable baffle. This is mainly because I used a pair of fancy 4+” drawer pulls as decorative protective grills. The driver is mounted with screws through the back side of the baffle, and knurled nuts for the securing process. There is some thin window stripping as a sealing gasket for the baffle, and 4 screws toward the front edges of the two adjacent sides to hold it in place. Permatex/Loctite Black Silicone seals the driver from leaks. Learn from this mistake- I was cutting the hole for the terminal cup (post assembly) and cut into the center partition. Since I did not want to restart the enclosures, I flipped the cup upside down. This allowed me to seal the cup to the inside partition, and effectively save the project. Please cut your terminal cup carefully.

Crossover/Shaping networks:

Simply- There are NOT any used here. There is not anything but 18 AWG wire connecting the driver to the terminal cup. Please refer to the frequency response graphs for on axis and 30 degrees off axis. This is the flattest response I have ever seen of any driver in an enclosure, without any form of crossover components shaping the sound. Off axis response does not change much either, and is probably attributed to the abnormal looking phase plug. The bass definition is not bad either!

Conclusion:

WOW! One more time… WOW!! These have an incredible imaging capability. In my opinion, when used with a subwoofer, you would have to do an awful lot more to beat these for a 2.1 system setup. I can imagine that a 5.1 setup would have a very ambient and immersing experience. The detail is astounding, the extension is airy in the treble, and decent in the mid to bass region. I do believe the DCR alignment helped reduce xmax a bit for a smoother extended bass presence than it would have had otherwise. There were quite a few smiles on faces at Dayton’s DIY 2005 to confirm my opinions of this project. It’s not at all complex to construct, and will surprise all who hear it. Minus some bass deficiency in the last few octaves, I believe this driver to be the ultimate in full-range fidelity.

Updated 09-13-2011 at 08:15 PM by Wolf

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