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Original build thread here: http://techtalk.parts-express.com/sh...light=protocol
I like this picture because it makes the speakers look gigantic, even though they are fairly small.
This project came about from the desire to use the overachieving Vifa TC9 in a build. It is a great little driver with an easy to work with response and very nice distortion performance all at the low low cost of $12. I actually ended up buying my pair used from rpb last November for $10 IIRC and am just now getting around to using them. I picked up a pair of the Vifa XT25SC90 (small faceplate version of the XT25) in the classifieds to go with them for around $20 shipped. So then it came down to what woofer to use to make a nice 3-way. I debated for a while on what I wanted to do. I didn't really want to go with something pricey, since the rest of the build was so cheap. I also wanted something that could be stand-mounted to use in my bedroom (the eventual home of these). I looked around quite a bit and ended up deciding on another overachiever, the Dayton ND105-4. A lot of people tend to urge against going with small woofers for a 3-way, saying that you should either go with a good size woofer or just pick a pricier woofer for a 2-way due to costs. I definitely understand that logic, but here was my rational: The midrange on the TC9 is great and it is super cheap, but it definitely can't be used too low. The ND105 has crazy output potential for a 4" woofer due to its extremely large xmech and it plays down to 40hz in a roughly 7.5 liter cab. To get the combination of low extending bass and the midrange performance of the two, I would have had to go with a much more expensive, and probably larger driver, and a much larger cab in most cases. So going against the conventional wisdom on this, I decided to name them the Against Protocol 3-way, or AP3 for short. Total cost of the project using all poly caps except for the two largest values came out to just under $200 in parts. My total cost was about $150 since I got the ND105 on sale and the other drivers used.
Paul Carmody mentioned in a thread about the Event Horizon design he was working on that it was difficult to work with the small woofers in a 3-way due to the higher Fs interfering with the crossover between the mid and woofer. I noticed this problem as well, and it took a bit of finagling to get it to play nice. The crossover ended up fairly straight forward in the end. Second order electrical on the woofer LP and on the mid HP and LP, and third order on the tweeter.
I didn't have a lot of time to voice these and measure before NY DIY and the end response surprised me a bit, as it looks kind of hot in the treble. I've had some time to go back and adjust some values to see if it sounded any better with the tweeter level down or the mid level a little higher and I have decided to leave them with the crossover I took to NY. Other variations just didn't sound right to me.
Comments on the sound: I got pretty good feedback on them from Roman at DIY NY, which I take as a pretty big compliment. Most of the comments from everyone were on the midrange clarity. Anyone who was at the event, feel free to comment with your thoughts, even if you think they sucked :D My thoughts are that the TC9 produces a really great midrange. Everything is detailed but still really smooth. You can see from the distortion measurements that the midrange through the top end is extremely clean. The vocal reproduction on these speakers is excellent. The phase aligned really well on these and tracks from the bottom end to the top end almost exactly on top of each other. I think this is what contributes to the really nice vocals and midrange sound. The bass is impressive for a speaker of this size and it's pretty amazing to hear how low these little ND105's can go. I was also really surprised that they could fill Roman's shop, which is pretty large, at the levels we were playing. I'll probably never have them up that loud again, but it's nice to know they can handle it.
I like this picture because it makes the speakers look gigantic, even though they are fairly small.
This project came about from the desire to use the overachieving Vifa TC9 in a build. It is a great little driver with an easy to work with response and very nice distortion performance all at the low low cost of $12. I actually ended up buying my pair used from rpb last November for $10 IIRC and am just now getting around to using them. I picked up a pair of the Vifa XT25SC90 (small faceplate version of the XT25) in the classifieds to go with them for around $20 shipped. So then it came down to what woofer to use to make a nice 3-way. I debated for a while on what I wanted to do. I didn't really want to go with something pricey, since the rest of the build was so cheap. I also wanted something that could be stand-mounted to use in my bedroom (the eventual home of these). I looked around quite a bit and ended up deciding on another overachiever, the Dayton ND105-4. A lot of people tend to urge against going with small woofers for a 3-way, saying that you should either go with a good size woofer or just pick a pricier woofer for a 2-way due to costs. I definitely understand that logic, but here was my rational: The midrange on the TC9 is great and it is super cheap, but it definitely can't be used too low. The ND105 has crazy output potential for a 4" woofer due to its extremely large xmech and it plays down to 40hz in a roughly 7.5 liter cab. To get the combination of low extending bass and the midrange performance of the two, I would have had to go with a much more expensive, and probably larger driver, and a much larger cab in most cases. So going against the conventional wisdom on this, I decided to name them the Against Protocol 3-way, or AP3 for short. Total cost of the project using all poly caps except for the two largest values came out to just under $200 in parts. My total cost was about $150 since I got the ND105 on sale and the other drivers used.
Paul Carmody mentioned in a thread about the Event Horizon design he was working on that it was difficult to work with the small woofers in a 3-way due to the higher Fs interfering with the crossover between the mid and woofer. I noticed this problem as well, and it took a bit of finagling to get it to play nice. The crossover ended up fairly straight forward in the end. Second order electrical on the woofer LP and on the mid HP and LP, and third order on the tweeter.
I didn't have a lot of time to voice these and measure before NY DIY and the end response surprised me a bit, as it looks kind of hot in the treble. I've had some time to go back and adjust some values to see if it sounded any better with the tweeter level down or the mid level a little higher and I have decided to leave them with the crossover I took to NY. Other variations just didn't sound right to me.
Comments on the sound: I got pretty good feedback on them from Roman at DIY NY, which I take as a pretty big compliment. Most of the comments from everyone were on the midrange clarity. Anyone who was at the event, feel free to comment with your thoughts, even if you think they sucked :D My thoughts are that the TC9 produces a really great midrange. Everything is detailed but still really smooth. You can see from the distortion measurements that the midrange through the top end is extremely clean. The vocal reproduction on these speakers is excellent. The phase aligned really well on these and tracks from the bottom end to the top end almost exactly on top of each other. I think this is what contributes to the really nice vocals and midrange sound. The bass is impressive for a speaker of this size and it's pretty amazing to hear how low these little ND105's can go. I was also really surprised that they could fill Roman's shop, which is pretty large, at the levels we were playing. I'll probably never have them up that loud again, but it's nice to know they can handle it.
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