2. amps-preamps
  3. 147887-5435

Amplifier current vrs watts; why is current more important?

Lately when talking to knowledgeable people in the audio industry I’ve been hearing how current delivery is more important than watts in determining weather an amplifier will drive a speaker.
So what exactly is current and how does it effect speaker performance? How can a amplifier rated at 150 watts into 8 ohms vs one rated at 400 watts into 8 ohms be a better match for a hard to drive speaker?
hiendmmoe
hiendmmoe
unsound
7,329 posts
 

It would seem to me that if one wanted to tailor the frequency response; it could be done more specifically and more consistently with an equalizer than with the chance of amplifiers not lining up with impedances of loudspeakers in just the right manner towards that end.

In that loudspeakers have mechanical considerations that amplifiers do not; it seems quite understandable that it would be much more difficult to build loudspeakers with truly flat impedances, than to build amplifiers that can linearly adapt to fluctuating loudspeaker impedances.

Having a linear base line is an important consideration towards the goal of "high fidelity". Even if one wanted to deviate from that goal, amplifiers that can better adjust to loudspeaker impedance fluctuations would be easier to use with the afore mentioned equalizers.


georgehifi's avatar
georgehifi
10,312 posts
 
 it could be done more specifically and more consistently with an equalizer than with the chance


So true, why have an amp that can't maintain a flat frequency response, into a speakers wavering impedance load, you may as well have a graphic equalizer, at least with it you can pick where the boost and cuts of the frequencies are going to be.

  Look below at the black wavy line, that is the frequency response you will hear!!, and that's into an easy simulated speaker load, a hard load will be even worse

This is the well known Prima Luna Prologue Premium 25w tube amp with very questionable current.

8ohm tap + - 7db!! frequency response, "a tone control"
https://www.stereophile.com/images/1116PLPPfig01.jpg

4ohm tap+ - 5db!! frequency response "still a tone control"
https://www.stereophile.com/images/612PPPfig01.jpg

Here is the Pass XA25 25watter with far more current that the PL above, it’s +- 0.1db frequency response. Virtually flat as it should be!!!
https://www.stereophile.com/images/218PXA25fig1.jpg

Cheers George
mijostyn's avatar
mijostyn
8,570 posts
 
With digital room control you can do whatever you want as long as you have enough power, volts and current to support the corrections. Power is everything in a SOTA system. The problem with low power high efficiency solutions is that power requirements are geometric. They go up dramatically with peaks. Low power systems can't support this unless you just listen to string quartets. The other problem, and this is my ears talking, is that horns always sound like PA systems to me.
An amplifier is a voltage source. It's job is to pump electrons stored in the power supply into the speaker. If the speaker is high impedance fewer electrons (current) are required to do the job. Lower impedance than more electrons. If the power supply runs out of electrons all the pumping power (voltage) in the world will not do any good. None of this says anything about efficiency.  
pushpull
17 posts
 
In a simple DC circuit, Amps = Volts/Resistance. Watts = Volts X AmpsUsing the water analogy, Voltage is the pressure pushing the water thru the pipe, Amperes,(current) is the volume of water & Resistance is the size of the pipe restricting flow. When you introduce AC current with coils, capacitors & such things get much more mathematically complicated, as the previous posts outline. Thank Heaven for the brilliant engineers who design our great gear.
gkr7007's avatar
gkr7007
151 posts
 
As a Magnepan owner I will tell you I went through a couple amps trying to get the best out of them.  Maggie's are notorious for chewing up lesser quality amps and spitting them out.  They literally put one amp of high wattage into protection mode within 5 minutes and cooked the power supply.  I had a couple of monos built with about 220 watts but monster current and I finally heard all that the Maggie's had to offer.  Too much emphasis on watts.  

More to discover