Home Forums DIY Speakers and Subwoofers Argh!!! Choosing Drivers Reply To: RE: Argh!!! Choosing Drivers

  • 123toid

    February 19, 2021 at 9:14 pm
    Posted by: @deadeye

    How in god’s name do you go about choosing the drivers!!!???


    I know 8″ is the biggest I can go and from my car subwoofer box building days (25 years ago) I prefer a couple of smaller drivers than 1 big one for more “punch”.


    Passive Radiator? Port? Sealed?


    These will probably be crossed over at 80Hz anyway so why agonize so much!?


    How do you choose your drivers?

    This is a really good question.  There is no real wrong way to do this, but I will give you my advice.  And the basics of what I do.


    First, I would start with the woofer or mid (assuming two or three way).  Make sure that whatever alignment you choose it will be able to go to the frequency you want it to.  So if you want it sealed and crossed over at 80hz, you will want to find a driver that can do that. 

    Once you have this narrowed down, not it’s size.  Ever driver will start beaming by a certain point. That means that the driver will start to deviate from it’s on axis response. this is completely dependent on the driver size chosen. For example if we take a look at an 8 inch woofer were going to see that it starts to deviate from its own axis around one kilohertz. And it starts getting a lot worse around 3 KH. that means that if we take this driver and crossover during this area, are off axis response will suffer. So you typically want to crossover closer to the one kilohertz with a 8 inch driver. That doesn’t mean you can’t go later, just means that you’re off axis myself for a little.  Another thing you wanna look at when you’re looking at the driver is it cone break up. you’re gonna notice that with some pretty sharp peaks in the response. this should be well after your usable frequency range. you wanna make sure to get that down as far as you can come and see don’t get distortion in your final build.

    Once you have the woofer or mid picked out you want to move onto your tweeter. you’ll notice I didn’t start with the tweeter, because I didn’t know where I would want to crossover yet. If I have the idea of doing a 2 way with an 8 inch driver, I’m gonna need a tweeter that can crossover relatively low. so I probably don’t wanna crossover any later than 1500 Hertz if I can help it. for this wanna take a look at 2 things. I wanna check the sensitivity of the tweeter and I want to check out it’s FS. Typically a good rule of thumb to follow is not to crossover any higher than 2 times the FS of the tweeter. so you’d be looking for a tweeter with an FS around 750 Hertz or lower. You would also want to look free tweeter that is more sensitive then the woofer or mid that you’ve chosen. let’s do the fact that you wanna be able to attenuate it to match the mid. You do not want attenuate the mid in a 2 way build.

    What I have mentioned are basic rules of thumb.  But it should help as you learn.

    Reply To: RE: Argh!!! Choosing Drivers