Speaker impedance question

[polo16mi]

If you may have to pick a speaker, what incline your decision to an impedance or other? 

Wich is best for what?   4 or 8 ?   I mean.... imagine that you have  100W over 4 ohms and 100W over 8 ohms?

I guess that the same power over 4 ohms push the amp output twice the current that 8 ohms, but if you get a side this, how affect your choice at the sound? 

[joecool85]

If you may have to pick a speaker, what incline your decision to an impedance or other? 

Wich is best for what?   4 or 8 ?   I mean.... imagine that you have  100W over 4 ohms and 100W over 8 ohms?

I guess that the same power over 4 ohms push the amp output twice the current that 8 ohms, but if you get a side this, how affect your choice at the sound? 

4 or 8 ohm shouldn't effect the sound of your amp one way or the other directly.  Its all about matching the speaker to your amp.  Most amplifiers put out more watts, but with less clarity, as you go down in ohms.  IE - you get 50w @ 8ohms for an LM3886, but 68w at 4 ohms.  I think the THD is the same in that case, but I do know that the LM3886 gets a LOT hotter running at 4 ohms.

Hope that helps.

[Enzo]

The real question to me would be whether you plan to use multiple cabs.

If you use one cab, it can pretty much be whatever you want.  But if you have a 4 ohm cab, it gets difficult to add another.  If you start with 8 ohm speakers, you can add another 8 ohm cab and stil have a 4 ohm load for the amp.  or start with 16, add a 16 for 8.

[joecool85]

The real question to me would be whether you plan to use multiple cabs.

If you use one cab, it can pretty much be whatever you want.  But if you have a 4 ohm cab, it gets difficult to add another.  If you start with 8 ohm speakers, you can add another 8 ohm cab and stil have a 4 ohm load for the amp.  or start with 16, add a 16 for 8.

Actually, you can have two 4 ohm cabs, run them in series and have 8ohms seen at the amp.  It's all in how you wire your jacks in the cabs really.

But you are right, general convention suggests hooking them all in parallel, and in that case if you are planning on having more than one cab it is good to go with 8 or even 16ohm cab setups.

[Brymus]

I dont own one but I like the way Marshall had some cabs set up with a selector
So you could have a stereo cab at one impedence or a mono cab at two others all with a twist of a knob.