A The most likely cause would be a two-way speaker that has a bad woofer, so I would triple check that before you move on. One of the easiest ways to check is to swap speaker wires between the two rear speakers. If the problem moves to the other speaker, then it is not a speaker fault.
If your rear speakers are sharing the output of the amplifier with the subwoofer, then you can have interesting effects occur when you play with the balance control depending on the amplifier used. Most notably, your subwoofer output can diminish, creating the illusion that the Kappa's woofer is not working on one side of the vehicle. This can affect a variety of "mixed mono" capable amplifiers and is fairly normal, providing everything works well in the center balance position.
Q Hello. I hope I'm not bothering you, but a friend of mine told me that you could answer a technical question for me. Here goes: I bought two of the Alpine 10" Type R Dual Voice Coil subs (SWS-1040D). The impedance is 4 ohm + 4 ohm (obviously!). A technician told me that I MUST wire up both sides of the voice coil, in parallel or series, making it a 2-ohm or 8-ohm speaker, respectively. Is this true? I can't just wire up only one side? I want a 4-ohm speaker! Please let me know if you think the technician is wrong. Any help you'd give me will be highly appreciated.Thank you!Respectively,David Derr, Faithful ReaderVia the Internet
A There are two contexts for this question. The minor context is technical and the major context is functional. The technician is technically wrong on the minor point of insisting that both coils MUST be connected, but is correct on the much more important broad topic of why you MUST connect both coils for functional reasons.
If you were to connect only one set of coils per speaker, your amplifier would encounter a load of 4 ohms, as you wanted. Nothing would blow up, or shut down or cause any other problems. In contrast, leaving one wheel off of a motorcycle is definitely a problem. The only real opportunity for a problem is if your unused coil connections were to short-out or contact chassis metal.
The major topic is "why would you ever use only one coil of a dual voice coil woofer?" You likely don't need a 4-ohm speaker since almost every amplifier made for at least the past three years can easily handle a 2-ohm load without a problem. You haven't specified what amplifier you are using, but I would bet it was designed to function properly at 2 ohms. In addition, by not using both coils, you are depriving yourself of the maximum performance that a dual voice coil subwoofer can provide.
Also with a dual voice coil speaker you can connect all four coils in a series parallel arrangement that provides 4 ohms. This resulting load can be connected to a bridged amplifier with great results.
The flexibility of dual voice coil speakers also allows you to add another pair of the same woofers later, and use the same amplifier now connected in stereo at 4 ohms per channel. As you continue to build your system, you can add a second amplifier, bridge both of them and gain the benefit of increasing your system performance one economical step at a time.
Please send questions to: Car Audio and Electronics, c/o Tech Panel, 774 S. Placentia Ave., Placentia, CA 92870 e-mail: techpanel@mcmullenargus.com