First 3-way (crossover)

I’m new to crossover design and have only ever used pre made boards but now I’m making one. It’s a three way using a nd105-4, a dma-804 3in, and a ptmini-6 planner for small desktop speakers. The woofer and mid are 4 ohms and the tweeters 6 ohms. The sensitivities are all different by about 1 to 2 db higher or lower. Idk if I need resistors or not because I’ve heard many people say that the amt tweeter (the highest sensitivity driver) is not as loud as it seems in its sensitivity rating? I looked up a 3-way crossover calculator and it said that I need a 5.3 uF cap, a 87.6 uF cap, a .11 mH inductor, and a 1.27 mH inductor. But I can only find a 5.6 uF cap, a 100 uF cap, a 0.10 mH ind, and a 1.2 mH ind. would these still work?
 

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diyAudio Moderator
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Try adjusting the impedance values in the calculator to see what happens to the other component values if you place a resistor in series. You'll probably want to have more components on hand for testing. Not only for this, but also due to the fact that the calculator is not an accurate method of design.

( :cop: Moved to Multi-Way)
 
diyAudio Moderator
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There is nothing wrong with the site. It is the procedure that is the problem as it doesn't take into account the properties of the speaker which vary with frequency.

The first order crossover you are looking at is fairly receptive to tweaking by ear, in case you aren't planning to measure. It simply means you'll need to try different values, not only to separate the bands but to set the levels.
 
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That doesn’t look bad but I’m using the 4 inch as more of a small sub with it’s matching prs and so I’ll keep in the mid to lower distortion and raise the soundstage. I’m switching the design a little so I’m looking for a smaller midrange to fit the new design. I still haven’t picked the new mid driver but it’ll need to be a 2 1/2 (or 2 in) and it’s going in a TMW configuration. Hopefully it’ll smooth out the 500-5k range. I’m also curious on what software you used?
 
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Two questions first... How big can your cabinet be? What kind of amp do you plan to use?

A 3-way is MUCH harder than a 2-way. If you are going to use a small budget amp, then you could use a 2.1 amp and build it as a TMW but just run the TM off the stereo output and the Woofer off the 0.1 subwoofer output.
 
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Based on what you have said, here are two ideas:
  1. Build a TM two-way with a woofer on the bottom powered by the 0.1 channel from the amp. (i.e., it would look like a TMW three-way from the front.) PTmini, PC83-8 and a 4 inch woofer will easily fit on your baffle. Compare the TCP115-8 to the ND105-8 for the woofer (subwoofer) duties. I think you could just run a splitter from the amp to the two woofers, which would wire them in parallel and they would operate as a 4 ohm. It would be a mono signal, but below 100hz I don't think that matters. Build an interior SEALED enclosure of about 0.6-0.7 cf for the PC83. then use the remaining volume for the 4" (sub)woofer.
  2. Build a smaller two way using the PTmini and PC83-8. You could even go with a 3-1/2 inch or 4-inch mid here. You can go sealed as long as you can get an F3 of close to 100hz, but you could also go ported and have them go lower in frequency. Then just build a single stand alone subwoofer to run off the 0.1 channel. If you haven't heard of the Voxel subwoofer, check it out. It is the size of a shoebox and puts out pretty ridiculous bass for its size.