Axiom Home Page Forums General Discussion Technical Questions 220 volt vs 120 volt for subwoofers

Interestingly enough, the 240V circuit would see 4 times the impedance compared to the 120V circuit due to the turns ratio of the 240V transformer used on the EP500. As a result, the EP500 would draw half the current at 240V as 120V.

The power the EP500 needs doesn't change ... double the voltage then you'll need to halve the current.

I think Trevor was trying to calculate available power at the plug ... the numbers will be different depending on how you want to approach it. What Trevor presented was power used into a resistive load when the voltage is doubled. Although the math is correct, I do not think he's getting the answer he's after ...

Home wiring is only allowed to carry so much current for a certain wire size (for safety). For the same wire size doubling the voltage (i.e. only changing one variable, in this case voltage) gives you double the power. Now, if you want to change both current (wire size) and voltage ... which is valid in that standard receptacles are available for a number of voltages and amperages ... going from a 15A 120V outlet to a 30A 240V outlet will give you 4x the power.

Is the current halved because the power doesn't change or is the current halved because the equivalent input impedance is quadrupled?


True dat.

U tell me ..,, What’s the simplest explanation?

The simplest explanation is the current is an artifact of the subwoofer's equivalent input impedance being immersed in the applied electric field.

The current is halved because the 2 primary transformer windings would be changed from a parallel to two in series configuration with the switch. Look up dual voltage autotransformer.

Example Diagram.



Example with dual voltage autotransformer with 2 6ohm primary windings.

120v 2x 6 ohm windings in parallel = 3ohms So- 120v/3ohm = 40A

240v 2x 6 ohm windings in series = 12 ohms So- 240v/12ohm= 20A

That implementation results, as you've described, in a quadrupling of the input impedance.

Yessir

That's the simple explanation?? Hope you guys don't go into teaching

Hello Everyone,
Decided to go with 120 V supplied by 12 gauge wire and 20A breaker.( with the appropriate receptacles). I like the fact of making it easy, not something I typically do
Thank you for the great conversation material and all the comments

Vic650