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Watts and power

Can somebody break it down in layman's terms for me? Why is it that sometimes an amp that has a high watt rating (like, say, a lot of class D amps do) don't seem to always have the balls that much lower rated A or AB amps do? I have heard some people say, "It's not the watts, it's the power supply." Are they talking about big honkin' toroidal transformers? I know opinions vary on a speaker like, say, Magnepans - Maggies love power, right? A lot of people caution against using class D amps to drive them and then will turn around and say that a receiver like the Outlaw RR2160 (rated at 110 watts into 8 ohms) drives Maggies really well! I'm not really asking about differences between Class D, A, or AB so much as I am asking about how can you tell the POWER an amp has from the specs? 
redstarwraith
georgehifi's avatar
georgehifi
10,312 posts
 
redstarwraith
Why is it that sometimes an amp that has a high watt rating (like, say, a lot of class D amps do) don’t seem to always have the balls that much lower rated A or AB amps do?


It’s to do with current ability, not just watts, you can get a 3000!! watt Class-D here
https://djcity.com.au/product/behringer-nx3000-power-amp-with-smart-sense/

And into a pair of Wilson Alexia or similar speaker with low impedance’s to a given volume level, that 3000w will sound positively weak and anemic, compared to say a pair of 25 watt Mark Levinson ML2’s, yes that’s not a typo, only 25w!!

Current is just as important if not more than watts, and an amp that can almost double it’s tested 8ohm wattage for each halving of impedance 4ohm then 2ohm or even 1ohm is an amp that can do current very well


Cheers George
audiozenology
362 posts
 
sejodiren,
Your post is welcome, as it illustrates quite well this concept of "doubling into 4, doubling again into 2" is just a "lazy mans" spec. It sounds impressive, but only if the design is conventional, and even then, the only specification that matters is how many watts at your speakers lowest impedance.  300 watts into 2 ohms, and 150 into 8, is still better than 200 into 2 ohms, and 50 into 8.  The Proton, which does not increase that much into 4 / 2 ohms, has a design methodology based around real world music where peaks are short in length, and for those peaks, it can deliver significantly more power (headroom).   It's this headroom that makes an amplifier deliver above its rated continuous wattage (which you can only compare at the same impedance).


sejodiren102 posts12-21-2019 9:39pmRead the review for this Proton that I own. A lowly 40wpc but 6db of headroom. It makes my DQ 10's just sing compared to the Yamaha SS receiver I was previously using at 95wpc in 2 channel mode. I don't know a whole lot about the 'techy' stuff but I believe it's a class g/h? Incredible sounding 'little' amp for sure..... http://www.hifi-classic.net/review/proton-d540-410.html

audiozenology
362 posts
 
The Behringer is 1500 watts into 2 ohms, which is about the lowest impedance of the Wilson. There will be absolutely nothing anemic about it compared to the ML2, and that is obviously spouting uninformed nonsense, nothing actually related to reality.

1500 watts into 2 ohms is 27 amps.   The ML2 is 100 watts into 2 ohms ... or 7 amps.


"Current" is nothing more than watts at a given impedance.
1500 watts into 2ohm is always more than 100 into 2 ohms, especially when the lowest impedance is 2 ohms.  I get it, you don't like Class-D, but don't make up facts.
georgehifi's avatar
georgehifi
10,312 posts
 
and 150 into 8, is still better than 200 into 2 ohms,
Good luck finding a speaker that is a flat 8ohm pure resistive load, with no -phase angle

You listen to your $420 3000w Behringer Class-D’s, I’ll take the ML2’s any day of the week over the Behringer into quality speakers that are hard to drive.


There will be absolutely nothing anemic about it compared to the ML2
You listen to one on the Alexia's, then you'll know.
Listen to what your saying and we’d all using $420 3000w class-d PA amps
optimize
164 posts
 
I am so tired on insufficient information from the manufacturers..

They only tell us power in wattage (in one or another way).
From school it is amps multiplying with voltage gives wattage.

Where we consumer only have wattage then we can not know much of each component the amp gives for example get 100 watts.

Is it 2 amp and 50 volts ?
OR
Is it 4 amp and 25 volts ?
OR
Something completely else?

Some speaker technology types benefits if the wattage consists of high amount of ampere.
But we will never know which amps that delivers a lot of ampere..

Just a another small factor to add to the list.. 🥰
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