ohms, crossovers

You want to build a custom sound reinforcement system.  That's cool.  Let me look at the drivers you've picked out and make a few suggestions...Support the12volt.com

OK, here's what I'd suggest.  Since you like the Selenium high frequency driver, buy two of those.  You'll also need a screw-on horn for each one, such as Parts Express part number 270-300.  Make the system a 2-way not a 3-way.  Purchase four of the Eminence Alpha 8A woofers.

Build your enclosure so that there are two chambers with approx. 1.5 cubic feet of space inside for each set of woofers.  Mount two woofers and one tweeter for each side.  Port each side at about 41Hz, which is most easily accomplished using a piece of 4" ID PVC pipe cut to 10.5" long.  The port can face any direction that is convenient

I suggest building a second order crossover at 2.2KHz.  Wire the two woofers in parallel (a 4-ohm load) and the crossover will consist of one inductor of 0.58mH in series and one poly cap at 9 uF in parallel.  Use an air core inductor of at least 16 gauge.

In series with each tweeter will be a cap of about 4.5 uF and in parallel an inductor of 1.16 mH.  This cap should be a high quality poly or film/foil cap, and this inductor can be a cheap one with iron core.  I also suggest using an L-pad such as parts express part number 260-265 for each tweeter as they are about 8db more sensitive than the woofers in parallel.  NOTE that since this is a second order network, the tweeter must be in reverse polarity in relation to the woofers.  The negative speaker terminal connects to the positive input terminal through the l-pad and in-series cap.

This system should be quite musical and will hit about 120db with 125 watts of power, with sufficient long-throw characteristics to be used outside.

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Great! Thank you DYohn, If I'm understanding you correctly, it should look something like this: I was considering upgrading to the better Selenium Drivers (the D220Ti 264-270) if you think that's worth the extra $13 a driver, it's still within my budget? And am I reading correctly when you suggest four inch inside diameter PVC? I'll have to get to work on designing a shape that will house that big of pipe. Thanks again. I'm going to start drawing things up.

I realized last night after shutting my computer down that I forgot about the L-Pad in my drawing. Will have to draw that up today.

Yes, your schematic is correct for the Xover layout, just missing the L-pad.  Using the higher end compression driver is a good thing as it has better frequency response and power handling.  It has higher sensitivity numbers so you'll REALLY need to pad it down.   If you can't add a vent to the enclosure it will still function as a sealed system.  You'll just lose low-frequency output level.Support the12volt.com

Ok, redrew the schematic (need to get out of rookie status so I can edit my posts). The L-Pad in the drawing is just a representation as I'll use the adjustable one from parts express. They also have an adjustable flared 4" port as well which I may use to pretty up the enclosure but that would add an additional inch to the length using flared ports. I think you've set me on the right track! Thank you sir! Below is the schematic, parameters, and speakers (showing the D220's because the Seleniums weren't listed in X-Over Pro)

Cool.  It's actually a second-order Linkwitz-Riley network, not a Butterworth.  But that's not really important.  You can use a lower gauge than 16 for the parallel inductor which will save you some money, but do use at least 16 for the air core.  Plus as you say, the specs given for the tweeter are not the same as what PE lists on their web site...  Looks like you're ready to go for it!  

edit: If you can't find the exact values for the caps and coils, you can be within 5% to 10% and not alter the function significantly.  If you need help with suggested parts, let me know.

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Thank you DYohn, I really do appreciate the help. I had already looked up most of the parts last night and couldn't find exact matches but got fairly close. Definitely within a 5% tolerance. Below is the complete parts list at right around $400: Solen 4.7uF 400V Polypropylene Capacitor (027-552) Solen 9.1uF 400V Poylpropylene Capacitor (027-566) 1.0mH 18 AWG I Core Inductor (266-550) Jantzen 0.60mH 15 AWG Air Core Inductor (255-412) L-Pad 100W Mono 3/8" Shaft 8 Ohm (260-262) L-Pad Knob and Faceplate for 3/8" Shaft (260-271) Precision Port 4" Flared Port Tube Kit (268-352) Eminence Alpha-8A 8" PA Driver (290-401) Selenium DH200E-E 1" Titanium Horn Driver (264-225) Dayton H110 1" Constant Directivity Horn 90x40 (270-300) 8" 2-Piece Steel Mesh Speaker Grill Black (260-424)

Great.  Be sure to post build pics and to give us your impression of how it sounds. Support the12volt.com

DYohn wrote: Great.  Be sure to post build pics and to give us your impression of how it sounds.Â

Will do and I just can't thank you enough for helping me out. Ended up going with the better Selenium HLCDs so the total was right at $450. Parts-Express is only 40 miles from my house so I'll probably have all the components tomorrow. Will start the build this weekend an post pics. The only quest I have is, does it matter what order I Place the speakers? I was thinking of putting the tweeters on the outside with the port in between each woofer like this: Tweeter Woofer Port Woofer (oO∙O) (O∙Oo) Woofer Port Woofer Tweeter Thanks again