Car Stereos: Bridgeing a 900x2 Pheonix Gold amp to 2 12 Memphis subwoofers in a ported box., ohm voice coils, dual voice coil

Question

Your diagram My amp is bridged but i do not think i have it done right because at a certain volume the amp goes into protection mode until i turn it down. I read one of your articles about bridgeing two peakers to a 2 channel amp to get the 4 ohm but is that for a cealed box or can it work for a custom ported box as well. My subs are dual voice coil subs and my amp has a subsonic filter. It is an old amp but still pushes like brand new i have not ever had this problem before and i am stumped. I have not taken the speakers out of the box so i am not sure of the rating but i looked up a similar pair and they say they are rated at 400 watts each and i am using a Pheonix Gold 900x2 amp. I am just wondering if the wiring diagram you should would be the right one for my speakers. They hit really hard but just to a certain volume.

Answer
Hi Jason,

The type of box (ported vs. sealed) doesn't matter when it comes to the subwoofer's impedance.  A particular wiring configuration will give you the same ohm level, regardless of the box type.  The diagram you attached will usually be the right one for connecting two subs to a 2-channel, bridged amp; but it also depends on the impedance ratings of the subs.

Most dual voice coil subs use 4-ohm voice coils; when wired as in the picture, you'll end up with a 4-ohm load at the amp, which is ideal for a bridged amplifier.  However, if your subs use 2-ohm voice coils, you'd end up with a 2-ohm load, which is too low for most amps in bridged mode.  

You might try connecting one sub to each channel, instead of bridging the amp.  This will reduce the power output, but it may still get loud enough for your needs, and it will be less strain on the amplifier.

If you have a defective sub, or sloppy wiring at the terminals, it can also result in the amplifier going into "protect" mode.

Hope this helps!

Brian