Question about high current amps versus "not high current amps"
Recently I read a reply to a post about a certain speaker, and the person who replied typed that (and I am going to paraphrase somewhat) the speaker required a high current amp to perform well and it wasn’t the WPC that was important.
Sorry as I am afraid that these are probably going to be "audio electrical questions for dummies," but here goes:
I vaguely remember being taught the PIE formula, so I looked it up online for a quick review and if I am understanding it correctly,
P (power/watts) = I (current/amps) x E (electromotive force/voltage) .
My first question would be: if I am understanding that correctly, how can wpc NOT matter since watts are the sum of current x voltage? I mean if you have so many WPC, don’t you then HAVE to have so much current?
My next question would be, if I am understanding PIE correctly, is E/voltage going to be a fixed 110 vac out of the wall, or is that number (E) determined by the transformer (so it would vary by manufacturer) and it is that (different transformers that are used in different amps) going to be the difference between a high and a lower current amp?
Or am I completely off base thinking that P is wpc and P is actually the spec in my owners manual that lists "power consumption as 420 watts operate 10 watts stand by"?
And lastly, what would be an example of a high current amp and what would be an example of a low current amp?
Thanks.
@dlevi67 that was a good summary from an engineering perspective, and a good introduction to Ohm's Law, which is exactly how I learned from other engineers (fellows) when first designing amps and speaker systems as a hobbyist. The others came in nicely with the nuances regarding load, sensitivity, etc |
Given the same 100 RMS 8 Ohm amp/circuitry, but one power supply with 1000 micro F and the other with 100,000 micro F. Speaker has an impedance dip to 2 ohm at 100 Hz. Can the 100k cap amp not provide a LOT more amps (for 1 millisecond) than the 1k cap amp? Isn't that were the "100 Watt RMS, 200 Watt PEAK" nomenclature comes into the picture? |
The PIE forumla works but you need to know the amp rail voltage and not the wall outlet voltage. The best way to find a robust, high current amp is to find one that doubles the wattage output at 4 ohms and has 2-ohm capability. Example 200 watts at 8 ohms and 400 watts at 4 ohms. Most Pass Labs and McIntosh amplifiers do this very well for example although Macs use autoformers to make sure they are stable at the desired impedance. An amplifier that has the same output at 4 ohms and 8 ohms is an example of a less robust, low current capable design. |
