Here is a quick video on how to tune and place subs for an end-fire or cardioid array
This includes all the math you need to create an effective directional sub array with as few as two subs
There is a downloadable PDF on the channel members Telegram channel. There is a link in the members dashboard posts.
If you like this and other videos I do, please join this channel to get access to more videos, early access to videos as well as to be able to join my weekly zoom chats:
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Also check out:
http://www.soundymcsoundface.com
https://www.ratsoundsales.com/
https://ratsound.com/daveswordpress/
https://www.ratsound.com/
http://www.soundtools.com
00:00 Step 1 - Determine Tuning
00:30 Step 2 - Calculate 1/4 Wavelength Distance
01:14 Step 3 - Subwoofer Placement
01:33 Step 4 - Calculate Time Delay
01:48 Step 5 - Add Delay and Polarity for Array Type
02:41 Compare Cardioid to End-Fire Arrays
03:06 Optional Step 6