Off the cuff, here are some tips about putting together DIY component speaker sets:
1) What fits? Maybe you’re in the tiny minority that is willing to cut and rebuild the door, for example, to fit just about any speakers. Most people want to keep new mid-woofers and such hidden or relatively modest in exposure to onlookers.
Consider available mounting depth. We want the windows to roll all the way down.
Consider space needed in front of the speaker up to the door panel. It’s not good for anyone if the speaker rubs against the plastics and gets ruined.
If you use a speaker fit guide the clearance in front of and behind the speaker will be taken into consideration for you. It might be assumed that the installation will be completed using an adapter bracket.
Consider tweeter placement and fitment. Does it need to fit in a new spot? Is there an existing tweeter location which you want to re-use?
A lot of aftermarket tweeters do not have any mounting solution except to flush mount, meaning it drops into a hole. When you get into “DIY” component speakers the tweeter mounting can leave people stumped. What if you don’t have a hole, or the hole is too small or too big? These are important questions.
Consider the intended application, sound-wise. Woofers(midbass, midrange) normally are not well-behaved on the top end even if they can play relatively high frequencies. This is why as you get into more complicated passive crossovers there are large parts dedicated to rolling off the top end of the woofers. (Low Pass Filter)
It can make for better sound.
Consider the crossovers. I often see people sharing links to generic passive crossovers, asking “Is this good for X mids and Y tweeters?” The short answer is the one people hate, HATE, to get but it’s true:
IT DEPENDS on what you want from your sound system.
This deserves its own discussion as it’s really misunderstood. How much power do I need to play good and loud? How much power is too much? What do I do when these tweeters I have saved in my shopping cart say they are rated for only 10W each? What the heck?
Matching tweeters to woofers:
It’s not this simple, but one shortcut to better sound is to try to have the sensitivity ratings close. If the tweeter is rated at 93 dB 1W1M sensitivity and the woofer is rated at 88 dB 1W1M sensitivity something needs to happen to make it sound good. For those still reading, my question for further discussion is:
What might need to be done to make this woofer and tweeter pair sound good together?