Output ransformer & amplifier

[dr.power]

Hi guys,

After audioguru respond a question of mine. I got another question and honestly made myself confused.

Suppose I have a LM3886 power amplifier which is a 68W amplifier, the said amplifier is connected to a 4 ohms speaker (I mean the speaker is suited to directly work by the said amplifier). now I want to use another similar speaker in parallel to the said speaker and use just the said LM3886 to drive the total load.
I know that now I have a 2 Ohms load so The amplifier itself is not happy to drive the new load. Now I decide to use a transformer to drive the said load. The question which I got is that what the transformer do for me? Yea, the transformer is an impedance marcher, But anyway Pin of the transformer is equal to Pout. So what I LOSE by adding the transformer instead of using a suited 2 ohms amplifier? Hope it makes sense,
If the transformer is able to causes my load to work at its Maximum power then I can just replace the transformer and use more speakers in parallel (I know that a can't do so, but I do not know what is the lost clue?)

Thanks for any help

 

[crutschow]

The clue is the fact that the transformer is an impedance matcher. This means the input and output turns ratio are different, with the impedance transformation equal to the square of the turns ratio. For an example, a transformer with a 2:1 turns ratio (primary to secondary) would make a 2 ohm load on the secondary appear as an 8 ohm load on the primary. Even though the input and output power (V x I) of the transformer are the same, the input voltage is higher and the input current is lower that the output voltage and current.

 

[alec_t]

Are you sure the amp can handle the extra intended load presented by the parallel speakers? If not, there will be excessive distortion, the amp overload protection circuit (if there is one) will kick in, and/or the amp will become a barbecue!