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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.

 

immatthewj
tomrk
87 posts
 

@sns "Not only low impedance  but impedance curves matter greatly as well."

Exactly.  The issue with the Watts/Amps equation is that it's generally used for power consumption in appliances and such where you have (almost) perfect sine waves.

Speakers are complex loads that change impedance and resistance constantly based on what you're trying to amplify.  A simple P = I x E doesn't quite capture that complexity.

The issue for audiophiles is manufacturers never give enough information to evaluate it nor can most people understand it, so you have to do the unthinkable.... Listen to the combination of speaker and amp that you want to use and turn the volume up.  Crank it.   If it sounds like crap it's probably not a good match for your use.

tomrk
87 posts
 

@mulveling  Is there a metric (number) for what constitutes a high current amplifier? 

atmasphere's avatar
atmasphere
12,003 posts
 

@tomrk I offered a good metric earlier; whether or not the amp can double power from 4 to 2 Ohms.

westcoastaudiophile
402 posts
 
@panzrwagn +1 simplest test of amp current handling adequacy is to tap low frequency. driver membrane and checking voltage waveform at speaker terminals with the scope.. if voltage amplitude p-p observed is more than 10mV, then need to check speaker connectors, cable, amp relay contacts, and then try higher current amp design to see if it helps!
westcoastaudiophile
402 posts
 
@panzrwagn +1 simplest test of amp current handling adequacy is to tap low frequency. driver membrane and checking voltage waveform at speaker terminals with the scope.. if voltage amplitude p-p observed is more than 10mV, then need to check speaker connectors, cable, amp relay contacts, and then try higher current amp design to see if it helps!
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