I have a question that has been puzzling me for the past couple of months. Why do subwoofers with dual voice coil come as 4 ohms when bringing it down to 2 ohms produces more bass? Wouldn't it sound logical to sell them already converted to 2 ohms?

 

not all amps support 2ohms, if they came like that then they would be limiting their customer base, therefore selling less subs which equals less money and to them that is all that matters.

 

BoostTed is correct. My sub amp, for example, is a 2 channel unit that I have bridged into 1 channel for my sub. When bridged, the amp can only handle a 4 ohm load, so I required a 4 ohm sub to go with it.

Technically, running lower impedence doesn't necessarily give you more bass. It simply gives you more power, and if you sub can handle it then you'll get more output from your sub. (More bass, in other words.) But your sub has to be able to handle the increased power, or you're likely to damage your sub.

On a related note, some sub manufacturers will give you the option of dual 4-ohm coils or dual 2-ohm coils. This gives you more wiring options to achieve the load you want for your specific amp setup.

Remember that you must wire both voice coils together when running a DVC (dual voice coil) speaker. This means, for example, a 4-ohm DVC speaker will only provide you with 8 ohms (in series) or 2 ohms (in parallel). My particular amplifier could not use this speaker as I need 4 ohms, and there is no way to achieve 4 ohms with that particular speaker.

Also remember that running a lower impedence in your amp will generally run your amp hotter. You have to make sure your amp can handle the load as well as the heat. Additionally, some amps often show sound quality degradation when running at lower impedences. This usually isn't a big deal with subs, though, since you typically can't hear the minor increase in THD in a sub.