Subwoofer Hi-Level Cable - Why Three Wire..?


Active Member
I am curious why a subwoofer high-level cable has three cables which are connected left positive, right positive and left/right negative...

If it is receiving two separate AC signals (left and right speaker) and has itself only one speaker (as my MJA Ref. 100 has) then does it just combine the two signals - is it that left and right speaker signals must be as near as dammit the same at lower frequencies..?

Also, why two positive connections and only one negative..?

Some clarification to ease my restless and tormented mind, please.


Distinguished Member
:laugh: When i saw the header I was going to reply:

stevegreen was going to write:

There are three wires so that two can be connected to the positive terminal (both left and right) and the other to a negative terminal

Glad I didn't now :laugh:


the front left and right channels are seperate channels so may create different sounds at different times. I f the sub didn't pick up from both channels it would only make the bass noise from one of the channels.


The reason is the 'negative' wire is actually a ground wire. Hence 2 seperate signals sharing the same ground.

If you look inside your amp you'll probably find the 2 neg speaker terminals go to 1 shared earth point inside the chassis.



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