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Do Watts matter

Ceko

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Short question: why do people seem to need more Watts all the time? Upgrading means power amps with more wattage for a lot of people (at least that’s my impression).

What does that basically mean? That you can pump out louder music? More dynamics perhaps?

I have a 50 Watt amp and I’m very happy with how loud it can play. But what would it mean if I’d hook my amp to a big poweramp? Would I notice any difference in sound? What do you think?
 
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MF 1000

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On my active system switching from dedicated 300 watt bridged monoblocks to 750 watt bridged monos improved the depth and clarity of the bass at the same listening levels - I am using 18” bass drivers though in huge cabinets
 

TheFlash

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Short question: why do people seem to need more Watts all the time? Upgrading means power amps with more wattage for a lot of people (at least that’s my impression).

What does that basically mean? That you can pump out louder music? More dynamics perhaps?

I have a 50 Watt amp and I’m very happy with how loud it can play. But what would it mean if I’d hook my amp to a big poweramp? Would I notice any difference in sound? What do you think?
Short answer: they don’t, but sometimes people think they do.
Longer answer: In my experience, and there are other threads touching on this, current is far more closely aligned with sound quality than power. I wasn’t entirely joking when I suggested elsewhere that one could do worse than buying amplifiers by the kilogram. Heavy transformers tend to kick out more current.
Manufacturers find it easier and cheaper to up the wattage than to up the amperage, and of course they then brag about that in their ads. They rarely give measurements for current. If you compare the higher wattage version directly with its predecessor it may well sound better but if you want to compare across valves and solid state, across amplifier class, etc then current should be your guide and, in the general absence of published figures, weight is usually not a bad proxy!
 
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DaveyTed

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Some years ago I asked the same question to an amplifier designer.
His opinion was that a volume pot was effectively a restriction and ideally would be set around half way (12 o'clock) position.
 

Fourlegs

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Short answer: they don’t, but sometimes think they do.
Longer answer: In my experience, and there are other threads touching on this, current is far more closely aligned with sound quality than power. I wasn’t entirely joking when I suggested elsewhere that one could do worse than buying amplifiers by the kilogram. Heavy transformers tend to kick out more current.
Manufacturers find it easier and cheaper to up the wattage than to up the amperage, and of course they then brag about that in their ads. They rarely give measurements for current. If you compare the higher wattage version directly with its predecessor it may well sound better but if you want to compare across valves and solid state, across amplifier class, etc then current should be your guide and, in the general absence of published figures, weight is usually not a bad proxy!
isn’t current merely watts divided by volts? In other words isn’t the current you seek and love directly proportional to the watts available.

if you want to compare across valves and solid state, across amplifier class, etc then current should be your guide and, in the general absence of published figures, weight is usually not a bad proxy!
Indeed with valves then weight is important but often more so for the output transformers rather than the power supply transformers. I remember David Shaw of Icon Audio explaining to me that the output transformers of the MB845 mk2 amps were one of the most important aspects of the design because they could output higher power (current in your language) at low frequencies without increasing distortion compared to the mk 1 version.
 

Rayymondo

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His opinion was that a volume pot was effectively a restriction and ideally would be set around half way (12 o'clock) position.
I sometimes wonder if I wouldn't be better off with a less powerful amp for this reason... I can never get past 10 o clock on my volume.
 
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Jules_S

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It's a more complex formula to calculate power in an AC circuit than DC but I hope I'm correct in saying that the basic principle applies - you can increase "power" either by increasing the potential difference (voltage) or the available current. Hopefully a cleverererer person will elaborate on and correct that 😁 but I think it's very easy to fudge the figures to make it look like you have a powerful amp without increasing its ability to provide driving current to the speakers, hence what is on paper a powerful amp can wilt under the pressure of a demanding load.

So I suppose to approach your question, whether or not you need a powerful amp depends very much on how easy the speakers are to "drive", i.e. if they have high or low sensitivity (need more "oomph" from the amp to generate a given volume level), if they have a low or high average (nominal) impedance and if that impedance is benign (fairly consistent across the frequency spectrum from lows to highs) or if it varies wildly between, bass, mid and high frequencies.

Amps generally don't like varying (reactive?) impedances, particularly when they go low, and if you have speakers that have this characteristic and / or a low sensitivity, then you're likely to need a more powerful amp to control and drive them well.

I'm sure there's a load of holes in that explanation and lots more electronics and physics to it, but that's my take on the basics. I shall be keen to learn more and stand corrected if I've got it wrong!
 

Andy Stephenson

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Isn't that something to do with speakers getting less & less efficient? Or, manufacturers recommending higher & higher power outputs to drive them?
Efficiency is a big part of it. My first system in 1975 had a 20w per channel amp driving speakers that were rated at handling 20w
It was by far the loudest I've used. They had 8 inch paper coned woofers and should be more efficient than the 5 inch woofers in my Tablettes.
I sure that it's not as simple as just this but it does make a big difference.
As I understand it every increase in volume of 3db requires double the watts. When I moved from 20w per channel to 30w per channel there was barely any noticeable difference in volume.
I'm sure someone will be along to put me right, but this is how I've always understood it to be the case.

Andy
 
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EddieRUKidding

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I like to think that more copper is better when it comes to amps.
 
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rabski

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Speaker efficiency, and the efficiency (and impedance) across the frequency range are the important things, as others have said already.

Efficient speakers with a relatively benign impedance curve need less power.

My LVs are quite happy with 10 watts or so, and will go more than loud enough with that. The B&Ws in our AV setup won't even disturb a small fly on the cones until you've got about 100 watts up 'em.
 

tuga

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Short question: why do people seem to need more Watts all the time? Upgrading means power amps with more wattage for a lot of people (at least that’s my impression).

What does that basically mean? That you can pump out louder music? More dynamics perhaps?

I have a 50 Watt amp and I’m very happy with how loud it can play. But what would it mean if I’d hook my amp to a big poweramp? Would I notice any difference in sound? What do you think?

It's all about fitness for purpose. Do your speakers need more Ws?
 

andrew s

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Power in a reactive circuit depends on the phase difference between the voltage and current. A pure inductance or capacitance doesn't dissipate any power!

I think the real world challenge power amps face is in delivering the required voltage and current significantly out of phase with each other. With real speakers the phase difference varies considerably with frequency.

Regards Andrew

PS I think most (all) quoted and measured powers are into pure resistance loads where the voltage and current are exactly in phase.
 
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