A different question on speaker ohm ratings

A few years back, I bought some (cheap) 12" speakers from Radio Shack to replace the woofers in my wife's stereo system. These speakers had a feature that would be really cool in a bass cab: each speaker could be wired for 4 ohms or 8 ohms. There were three lugs on each speaker and depending on how you connected to it, you either got 4 ohms or 8 ohms.

This would be a nifty feature on a bass cab- your amp could always put out full power regardless of whether you were running one cab or two cabs.

I figure there must be some major drawback to wiring a speaker coil this way, like a loss of efficiency or frequency response or else SOMEONE would have done it.

Any ideas on this?

 

All of the above I'm sure is true. What I'm really wondering is it practicable to build a high-quality musical instrument speaker with a tapped voice coil to allow easy selection of impedence, or is this undesirable for some reason?

 

OK, that makes sense. I'd assume different gauge wire is normally used to obtain different ohm ratings? (i.e.- approximately the same number of turns on the coil using a larger or smaller gauge wire to obtain the desired ohm rating). The "tapped coil" likely uses just one gauge of wire and you're either using ALL the turns on the coil or 1/2 of the turns on the coil depending on how you connect it. I can see where this would definitely compromise the coil performance.

The point would be having a more versatile speaker, especially when two cabs are used. You could vary the ohm rating to maximize your amp output regardless of whether you were using one or two speakers. Or lets say you have a 4 ohm minimum rated amp and you later switch to a 2 ohm minimum rated amp (the MBII and GB Neopak come to mind). You wouldn't have to swap your two 8 ohm cabs for two 4 ohm cabs to be able to use your amps full wattage.

Anyway, thanks for the comments. Sounds like it's not practical.