Genral Crossover Understanding

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nightfx
Posts: 23
Joined: Mon Jan 25, 2021 6:43 am

Genral Crossover Understanding

#1 Post by nightfx »

Hello All,

I'm working on some 4 mid driver SLAs with 16ohm speakers and am trying to understand how crossover calculators work and if they are even reliable. I've read the following in another thread:
With respect to the low pass to go from 8 to 4 ohms you halve the coil values and double the cap value. To go from 8 to 16 ohms double the coil values and halve the cap value.
From what I gather; these are 3rd order crossovers in most of the plans. I was wondering how to use a crossover calculator (like this one: https://www.diyaudioandvideo.com/Calcul ... Crossover/) to help understand these values and also understand what to do in the future when building from these plans with varying driver loads.

Thanks in advance for any help with my noob questions :)

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Bill Fitzmaurice
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Joined: Tue May 02, 2006 5:59 pm

Re: Genral Crossover Understanding

#2 Post by Bill Fitzmaurice »

Read this:
http://www.bcae1.com/xoorder.htm

Crossover calculators give a starting point, but they assume an exact resistive load, so I always test and tweak as required to come up with the best component values.

nightfx
Posts: 23
Joined: Mon Jan 25, 2021 6:43 am

Re: Genral Crossover Understanding

#3 Post by nightfx »

That was a great read and now things make a little more sense... Pieces I was clearly missing:
  • Adding additional drivers in parallel creates +3db from surface area increase
  • Adding additional drivers in parallel creates an additional +3db from the load increase on the amplifier effectively giving a +6db boost overall
  • Assuming above is true, Adding additional drivers in series creates +3db from the surface area increase but -3db from the reduced load to the amp netting 0db
  • Frequency response has a direct relationship with load (driver ohms) across the frequency band
Pretty sure I'm over simplifying things but at least now I understand having a starting point and needing to adjust. I also understand why you would want to keep a crossover simple and just use EQ :D

Thanks for the link Bill!!

jimbo7
Posts: 849
Joined: Fri Dec 28, 2012 10:45 am
Location: St. Louis

Re: Genral Crossover Understanding

#4 Post by jimbo7 »

Bill Fitzmaurice wrote: Fri Mar 04, 2022 11:30 am Read this:
http://www.bcae1.com/xoorder.htm

Crossover calculators give a starting point, but they assume an exact resistive load, so I always test and tweak as required to come up with the best component values.
If you could just post a great link to every question we ask here, just think of all the time you'd save! Maybe you could take up a hobby like model trains or crossword puzzles
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AT 18" JBL GTO804
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2x T39 24" 3012lf
Simplex 10 BP102

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