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The Canzonettas - Quick and Easy 2-way RS100P-8 and ND16FA
I'm happy to introduce my third design - the Canzonettas. Mozart used the term canzonetta to differentiate between the more serious arias and the shorter solo work in his operas. Since these speakers were designed to go together very quick and easily, I figured this was an appropriate name.
I was inspired by TC's recent NTSB thread, where he chose to use materials at hand and few tools. Since I had some drivers laying around that I wanted to build up, I used this inspiration to get at it!
The drivers I chose were the new RS100P-8 and the ND16FA. I had acquired the RS100's when they were the DOTD and the ND16FA's I had laying around from other projects. I plan to use the RS100P-8 in an upcoming 3-way design, so I thought I would build some small 2-ways to see how well they do before tackling them in a large 3-way.
There were a few main goals of this design:
1. Must be accomplished with a very minimal tool set. For me, I used a router (with Jasper jig) and a chop saw. Yep. That's it. (Assembly could be accomplished in numerous ways, but I chose finish nails with an air-nailer. Dovetail, tongue-and-groove, standard nail, biscuit, and face-gluing could also be used)
2. Cabinets must be accomplished with off-the-shelf wood and parts from a big-box store. No table-saws, circular saws, rips, or major alterations of the wood. Just simple cuts!
3. Capable of building a pair in less than a day (not including finishing).
Using these three simple rules, I created a ported cabinet using three pieces 1/2" by 5.5" by 4' wood available from the big blue store. Since these cabinets are relatively small, the 1/2" wood allowed me to make the cabinets even smaller and more manageable. My big blue store had 4 choices available in this wood size - Oak, Aspen, Poplar, and Pine. Any of these would have been acceptable, but I chose oak. The three pieces of 1/2 x 6 x 4 cost me $11/each, so it was $33 for enough to finish 2 speakers. Note that the "by 6" size of wood is actually 5.5" wide. While you're at the store, pick up a short piece of 1.25" schedule 40 PVC to use as the port.
The cabinet size is 5.5" by 6.5" by 11". Using this size, you can see how easy it is to get the cabinets formed from the existing wood. One 4' length is used to create the baffles and sides of each speaker. Simply cut 4 pieces that are 11" long. There's a small bit of leftover wood that gets tossed.
With the third piece of wood, cut out 6 pieces of wood that are 4.5" long. This will create the top, bottom, and internal support for the cabinets. Here's a quick snapshot from BoxyCad that shows how the cabinet goes together and a not-to-scale image of the cutlist:
The woofer, tweeter, and port are all centered on the baffle (2.75" from the edges). The tweeter is centered 1.25" from the top, the woofer is centered 4" from the top, and the port is centered 1.75" from the bottom. The internal support is mounted between 6" and 6.5" down from the top. There's a picture of that later. The resulting cabinet is about 3.85 liters and the speakers can reach down to the 60's!!! Pretty dog-gone impressive for a little 3" speaker.
The crossover design is a very simple 2nd-order electrical for both the woofer and the tweeter. They cross at about 2700Hz and have quite a deep reverse null when out of phase. Here's a snapshot of the crossover:
Here's a few resulting measurements of the speakers. First the shot showing the driver responses, in-phase, and out-of-phase measured at 1M:
Here's the measurements showing the off-axis response up to 45 degrees. Pretty dog-gone awesome, IMHO:
So far as the time-to-build, I was able to knock out the cabinets and assembly in about 7-8 hours, and I'm not terribly experienced. The fact that there's no ripping needed shortens the time dramatically. Provided you've got a router, these CAN be accomplished in one day or less!
More details to follow!
I was inspired by TC's recent NTSB thread, where he chose to use materials at hand and few tools. Since I had some drivers laying around that I wanted to build up, I used this inspiration to get at it!
The drivers I chose were the new RS100P-8 and the ND16FA. I had acquired the RS100's when they were the DOTD and the ND16FA's I had laying around from other projects. I plan to use the RS100P-8 in an upcoming 3-way design, so I thought I would build some small 2-ways to see how well they do before tackling them in a large 3-way.
There were a few main goals of this design:
1. Must be accomplished with a very minimal tool set. For me, I used a router (with Jasper jig) and a chop saw. Yep. That's it. (Assembly could be accomplished in numerous ways, but I chose finish nails with an air-nailer. Dovetail, tongue-and-groove, standard nail, biscuit, and face-gluing could also be used)
2. Cabinets must be accomplished with off-the-shelf wood and parts from a big-box store. No table-saws, circular saws, rips, or major alterations of the wood. Just simple cuts!
3. Capable of building a pair in less than a day (not including finishing).
Using these three simple rules, I created a ported cabinet using three pieces 1/2" by 5.5" by 4' wood available from the big blue store. Since these cabinets are relatively small, the 1/2" wood allowed me to make the cabinets even smaller and more manageable. My big blue store had 4 choices available in this wood size - Oak, Aspen, Poplar, and Pine. Any of these would have been acceptable, but I chose oak. The three pieces of 1/2 x 6 x 4 cost me $11/each, so it was $33 for enough to finish 2 speakers. Note that the "by 6" size of wood is actually 5.5" wide. While you're at the store, pick up a short piece of 1.25" schedule 40 PVC to use as the port.
The cabinet size is 5.5" by 6.5" by 11". Using this size, you can see how easy it is to get the cabinets formed from the existing wood. One 4' length is used to create the baffles and sides of each speaker. Simply cut 4 pieces that are 11" long. There's a small bit of leftover wood that gets tossed.
With the third piece of wood, cut out 6 pieces of wood that are 4.5" long. This will create the top, bottom, and internal support for the cabinets. Here's a quick snapshot from BoxyCad that shows how the cabinet goes together and a not-to-scale image of the cutlist:
The woofer, tweeter, and port are all centered on the baffle (2.75" from the edges). The tweeter is centered 1.25" from the top, the woofer is centered 4" from the top, and the port is centered 1.75" from the bottom. The internal support is mounted between 6" and 6.5" down from the top. There's a picture of that later. The resulting cabinet is about 3.85 liters and the speakers can reach down to the 60's!!! Pretty dog-gone impressive for a little 3" speaker.
The crossover design is a very simple 2nd-order electrical for both the woofer and the tweeter. They cross at about 2700Hz and have quite a deep reverse null when out of phase. Here's a snapshot of the crossover:
Here's a few resulting measurements of the speakers. First the shot showing the driver responses, in-phase, and out-of-phase measured at 1M:
Here's the measurements showing the off-axis response up to 45 degrees. Pretty dog-gone awesome, IMHO:
So far as the time-to-build, I was able to knock out the cabinets and assembly in about 7-8 hours, and I'm not terribly experienced. The fact that there's no ripping needed shortens the time dramatically. Provided you've got a router, these CAN be accomplished in one day or less!
More details to follow!
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