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Current: Power Line and Amplifier Amp Ratings

Hello,

I have little knowledge when it comes to power and alot of specifications relating to amplifiers. Hopefully some people here would be able to assist me with a few items.

My electrical sockets are currently all 15 amp.

I use a Musical Fidelity amplifier, an A300 Integrated, and the specifications mention that it can do 20 amps.

Does this essentially mean that if the amplifier was required to put out this amount of current, that it is limited by my electrical setup, or am I looking at two specifications that aren't related to each other?

If these are related, would I find a considerable improvement in being wired for 20a, with a 20a socket? When I ask this, I am not looking to find if benefit would come from a dedicated line, or changing wiring, simply from a technical perspective, if all things considered, things remaining exactly the same, but being setup for 20a instead of 15a.

Also, often I will see amplifiers that have a peak current output of say 50a, or 75a. Are these essentially meaningless high ratings if amp current is limited by your electrical setup?

Even if the above is true, is there anyway based on knowing your speakers specifications and graphs, and a certain volume level at a certain listening difference, to estimate how much current your amplifier is actually generating at typical levels, and at peak requirements?

Using my speakers as an example, they are about 87db/sensitivity, and a relatively flat 4 ohms across the frequency range.

Is it typical to find that despite the _ability_ to push our rediculous amounts of current, that most amplifiers rarely need to?

Please excuse my complete ignorance when it comes to these matters -- I have listened to many components an systems and know what sounds good to my ears, but I am still trying to understand some of the core concepts behind audio and power.

Creating short lists, and auditioning, buying value, buying quality. These are all positive things in the search for what you're looking for, but I'm sure that me understanding requirements and claims will also help me to determine exactly what and how much of certain things I need, and what is overkill.

Thanks for your help.
paris47a19e7

Showing 1 response by garfish

garfish
1,840 posts
 
Hi Paris; Your 15 amp outlet has plenty of capacity for your(potential) 20 amp output amplifier. And BTW, my McCormack DNA2 Rev.A (300 wpc 8 Ohm, 600 wpc 4 Ohm, and 1200 wpc 2 Ohm) can source a theorhetical 100 amps, but under practical conditions this would never happen and I plug it into a 20 amp dedicated outlet. And I wouldn't hesitate to use a 15 amp outlet either-- if that's what I had.

I suppose if you set volume at max. your amp could possibly source 20 amps (continuous) of current but bad things would be happening to the amp and likely the speakers. For the most part, high current amps are desireable as they can be more dynamic on music as they can draw increased current for milliseconds on dynamic "peaks". This is MUCH different than sourcing 20 amps continuous.

4 Ohm Speakers with a sensitivity of 87-- 8 Ohm rating (that's 87 dB at one meter with an input of one watt) will play at 87 dB with an input of 2 watts, 90 dB with 4 watts, 93 dB with 8 watts, etc.-- power needs to double for each increase 3 dB of volume. Room size, desired listening level, and speaker sensitivity will determine max. output. In average sized home rooms, 90 dB is pretty loud (IMO) and with your set-up it only takes 4 wpc to produce that volume-- at one meter. Where the higher power becomes important is in accurately producing dynamic peaks.

And watts can be converted to amps if you want-- I just don't remember how to do it. Good Luck. Craig
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