2. amps-preamps
  3. 192831-171531

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

Showing 3 responses by mclinnguy

mclinnguy's avatar
mclinnguy
750 posts
 

A Coda 16 has 280,000 uF of capacitance and can deliver 100 amps of current, per channel. 

A Gryphon Essence stereo has 440,000 uF, so can probably deliver more, note that is described as a 50 wpc amplifier. 

Going off the top of my head, I recall many years ago that a low end Sony home theatre receiver was labeled as a 100 wpc 5 channel receiver. When actually tested with all 5 channels running it produced 15 wpc. It probably had the same power supplies as a modern audiophile level DAC, needless to say it was not a high-current design. 

mclinnguy's avatar
mclinnguy
750 posts
 

I had thought capacitance had to do with instantaneous current delivery as well.

Obviously 100 amps through a 15 amp outlet is impossible for long periods. 

In theory as far as continuous power one can only have 80% of 15 amps x 120 volts = 1440 watts before the breaker trips, assuming the power amp is the only draw on the circuit. I don't know how short this time period is. 

But an amplifier is not a hair dryer, and we are not blowing our speakers or our ears with a sine wave.

@atmasphere so what might be the instantaneous currents provided in music reproduction, even for a few milliseconds? 

 

mclinnguy's avatar
mclinnguy
750 posts
 

@thecarpathian 

The capacitance reduces power supply ripple and attempts to feed the amplifier constant DC  voltages. 

Theoretically, the more muscle he has (capacitance), the more weight (low impedance speaker) he can lift with minimal strain.

But I thought when someone was really muscular, they had more ripples? cheeky

 

More to discover