Benifits of more power?

Soopafly49

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This might sound like a silly question but what exactly will adding power amps do to the sound?Does it just make it easier drive the speakers or is there more to it?
 

CnoEvil

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If you haven't done so, have a read of this (even if it's about speakers, it covers what makes a good amp): http://www.whathifi.com/forum/hi-fi/speakers-lets-define-an-easy-load

Power (as in lots of Watts), isn't always the answer....just read the adventures of Acalex and Roby, where a 35W amp walks all over a 500W one (in their opinion).
 

Soopafly49

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Thanks for the replies guys. looks like ive got some reasearch. Will I gain more control aswell if each speaker had its own power amp.
 

busb

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Soopafly49 said:
Thanks for the replies guys. looks like ive got some reasearch. Will I gain more control aswell if each speaker had its own power amp.

Possibly. Is a pre/power combo always better than an integrated? No, as with most things: it depends. One could bi/tri/quad amp each speaker with a mono-block power amp & go for a separate PSU for each in the extreme.

I'm considering buying a new power amp. I borrowed Primare's new single box stereo A34.2 class D for a week that retails for £2.2k - it sounded amazing. A friend thought it was a bit "dry" down in the bass. To me, it sounded very well controlled without any overhang into the lower mid. This is another area where low output impedance can help: tight bass without the slight lift my existing amp has. As an aside, class A/B amplifiers will start to fade & be replaced by class D with some of the market still being filled by class A for those not worrying about their electricity bills! Before I purchase, I may give a pair of the audiolab mono-blocks a listen - they would have to be very special indeed to beat the Primare.
 

busb

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There's no single (or simple) answer. More power equals louder is a true generalisation but there are a lot of further buts... Although many or most speakers have a nominal 8 Ohm impedence, this is not constant across the freqeuncy range. Real loads aren't resistive but reactive - this means that the voltage can lag or lead the current drawn, causing the load the amplifier "sees" as being very complex that can cause variations in frequency response. Equally important is the amplifier's output impedence as is the current that can be delivered across the frequency range.

Although a generalisation, low output impedence coupled with high power & good current headroom will drive speakers with challenging loads. Good design is more important than mere nominally high power output. Some speakers have more straight forward (flatter) impedance curves than others - they can be driven well with lower power. Much of the power an amplifier can deliver goes unused much of the time. I'm listening to music at low volumes as I type. My audiolab M-DAC's volume display read's -36dB. If I increase the volume to -33dB, I have doubled the power & "loudness" by increasing the level by 3dB. If I replace a 75Watt amplifier with a 150Watt one, it's potentially only 3dB (twice) louder. Similarly, if I reduce the level on my Dac's display to -43dB, I have decreased the volume (power or louness) by a factor of 10. Much general listening is carried out below (lets say) 5Watts only - where many class AB amplifiers are running in class A mode. Volume is very logarithmic so all that extra power goes unused much of the time which partly explains why a 10Watt amp doesn't sound particularly under-powered until you want trouser-flapping loudness! Another factor regarding volume is speaker sensitivity that determines how much power is required for a given level.

Some wiki links:

http://en.wikipedia.org/wiki/Nominal_impedance

http://en.wikipedia.org/wiki/Electrical_impedance

http://en.wikipedia.org/wiki/Loudness

http://en.wikipedia.org/wiki/Audio_power

http://en.wikipedia.org/wiki/Gain

http://en.wikipedia.org/wiki/Logarithmic_scale
 

CnoEvil

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busb said:
I may give a pair of the audiolab mono-blocks a listen - they would have to be very special indeed to beat the Primare.

Have you ever heard Bel Canto?.....if not, it should probably be on your list as well.
 

busb

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CnoEvil said:
busb said:
I may give a pair of the audiolab mono-blocks a listen - they would have to be very special indeed to beat the Primare.

Have you ever heard Bel Canto?.....if not, it should probably be on your list as well.

Thanks for the suggestion. Their REF150S would do the trick & is class D with full switch mode PSUs for £1.5k.

The level of detail from the Primare was jaw dropping. The imaging through my Arros was sublime: individual intruments could be discerned from others, their timbre was highlighted & the different recording venues such as studio or concert hall were very apparent. Vocals were very nicely rendered where breathing augmented the feeling of being close. the mix didn't particularly get projected forward but had depth & the amp never ever sounded pushed - perhaps a bit matter-of-fact at times. Top end was grainless, not over-emphasised, detailed where as the bottom end went deep, tuneful & controlled my Arro's 4 Ohm load with ease. The combination really did show how cr*p many pop recordings are: anything with amplitude distortion (volume pumping) sounded compressed & poor but no proper Hi Fi at any price will transform poor recordings & I don't want a systen that rounds off rough edges like I did 20yrs ago when my hearing was better! When I returned to my Restek amp, it sounded distorted by comparison, the Primare sounded that clean. The only aspect I wasn't sure about was that other amps sound more dynamic but that could be down to distortion artefacts - on paper class D should not have a problem with dynamic shifts. The build quality was up to Primare's usual high standards, it wasn't mine so I overcame the temptation to unscrew the lid & look inside! I never realised just how much difference amplifiers could make to a system - huge!
 

CnoEvil

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busb said:
Thanks for the suggestion. Their REF150S would do the trick & is class D with full switch mode PSUs for £1.5k.

The level of detail from the Primare was jaw dropping. The imaging through my Arros was sublime: individual intruments could be discerned from others, their timbre was highlighted & the different recording venues such as studio or concert hall were very apparent. Vocals were very nicely rendered where breathing augmented the feeling of being close. the mix didn't particularly get projected forward but had depth & the amp never ever sounded pushed - perhaps a bit matter-of-fact at times. Top end was grainless, not over-emphasised, detailed where as the bottom end went deep, tuneful & controlled my Arro's 4 Ohm load with ease. The combination really did show how cr*p many pop recordings are: anything with amplitude distortion (volume pumping) sounded compressed & poor but no proper Hi Fi at any price will transform poor recordings & I don't want a systen that rounds off rough edges like I did 20yrs ago when my hearing was better! When I returned to my Restek amp, it sounded distorted by comparison, the Primare sounded that clean. The only aspect I wasn't sure about was that other amps sound more dynamic but that could be down to distortion artefacts - on paper class D should not have a problem with dynamic shifts. The build quality was up to Primare's usual high standards, it wasn't mine so I overcame the temptation to unscrew the lid & look inside! I never realised just how much difference amplifiers could make to a system - huge!

You give very interesting insight......and I agree with you about the quality of the amp.

The Bel Canto is the only Class D amp that I have liked, which is why I suggested it (great CDPs and Dacs as well).
 

Craig M.

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CnoEvil said:
If you haven't done so, have a read of this (even if it's about speakers, it covers what makes a good amp): http://www.whathifi.com/forum/hi-fi/speakers-lets-define-an-easy-load Power (as in lots of Watts), isn't always the answer....just read the adventures of Acalex and Roby, where a 35W amp walks all over a 500W one (in their opinion).

that 35 watts could easily be misleading though if the amp can provide much more for short bursts (dynamic peaks). music doesn't need a million watt amp, probably around 10 would do it as long as it can respond with more when the peaks come along. a lot depends on the speaker it is attached to.
 

CnoEvil

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Craig M. said:
that 35 watts could easily be misleading though if the amp can provide much more for short bursts (dynamic peaks). music doesn't need a million watt amp, probably around 10 would do it as long as it can respond with more when the peaks come along. a lot depends on the speaker it is attached to.

Exactly the point I'm trying to get across.....don't judge a book by its cover.
 

shafesk

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Hey Soopafly, I think that if everything other trait between a less powered and more powerful amp is the same then the more powerful amp should have more dynamic reach. i.e they should be able to go from soft to loud instantly as they have power in reserve unlike the low powered amps. Mind you, some low powered amps can be decieving. Things get more complicated with current delivery though, some small amps can supply gobs of current and can end up sounding more in control than a more powerful amp when the going gets tough. So I think looking at watts isn't enough, you should also keep watt @ ohm figures in mind. Hope I made sense :?
 

Soopafly49

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Thanks for all he great advice. If I monoblock them which is what I/m planning. Will the front sound a lot to different to the rest of the speakers since they are running of different amps.
 
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One aspect of amplifier power that probably goes unrecognized its effect on speaker transient response – especially with regard to dynamic speakers. A dynamic speaker works by flowing current through a coil (or ribbon) that is suspended in a magnetic gap. As current flows back and forth, the coil moves in and out. It's just a particular type of electric motor. But, as you may know, an electric motor can also be used as an electric generator. If you force the coil to move in the magnetic gap, the system will generate a current in the coil. This is how a dynamic microphone works.

Generating that current also generates a magnetic field inside the coil that opposes the fixed magnetic field in the gap. In other words, as you push on the coil, the coil pushes back. The more current that is generated, the harder the opposing force - or damping force. The regenerative breaking systems in hybrid and electric vehicles work on this same principle where the current generated recharges the battery. But the maximum damping occurs when you actually short the terminals of the motor (speaker) because this presents the least resistance and allows the most current to flow.

Powerful amplifiers with high current capacity behave like very low impedance sources. In other words, connecting a speaker to a powerful amp is like shorting the speakers terminals. And we know that shorting the terminals generates the most breaking power in the coil.

Ok, so what does this have to do with transient response? We don't actually push on our speakers cones, right? As a matter of fact, we do push on the speaker – with the amplifier signal. The amplifier generates current to push on the speaker to make sound. Obvious enough. But what happens when the amplifier stops pushing on the speaker, or tries to force the speaker to move in a different direction? Well, dear old Isaac Newton tells us that objects in motion tend to stay in motion. The speaker diaphragm has inertia and it will keep on moving even after the amplifier signal stops. The speaker will overshoot changes in the amplifier signal and continue to "ring" in the absence of signal.

So how do we solve this problem? What we need is a good breaking system like we described above, right? And as we just learned, the best breaking comes from having a high current capacity amplifier. So if the speaker tries to shoot past its mark, we have the maximum opposing force to damp its motion.

Make sense?

Thomas
 
barefoot_sound said:
One aspect of amplifier power that probably goes unrecognized its effect on speaker transient response – especially with regard to dynamic speakers. A dynamic speaker works by flowing current through a coil (or ribbon) that is suspended in a magnetic gap. As current flows back and forth, the coil moves in and out. It's just a particular type of electric motor. But, as you may know, an electric motor can also be used as an electric generator. If you force the coil to move in the magnetic gap, the system will generate a current in the coil. This is how a dynamic microphone works.

Generating that current also generates a magnetic field inside the coil that opposes the fixed magnetic field in the gap. In other words, as you push on the coil, the coil pushes back. The more current that is generated, the harder the opposing force - or damping force. The regenerative breaking systems in hybrid and electric vehicles work on this same principle where the current generated recharges the battery. But the maximum damping occurs when you actually short the terminals of the motor (speaker) because this presents the least resistance and allows the most current to flow.

Powerful amplifiers with high current capacity behave like very low impedance sources. In other words, connecting a speaker to a powerful amp is like shorting the speakers terminals. And we know that shorting the terminals generates the most breaking power in the coil.

Ok, so what does this have to do with transient response? We don't actually push on our speakers cones, right? As a matter of fact, we do push on the speaker – with the amplifier signal. The amplifier generates current to push on the speaker to make sound. Obvious enough. But what happens when the amplifier stops pushing on the speaker, or tries to force the speaker to move in a different direction? Well, dear old Isaac Newton tells us that objects in motion tend to stay in motion. The speaker diaphragm has inertia and it will keep on moving even after the amplifier signal stops. The speaker will overshoot changes in the amplifier signal and continue to "ring" in the absence of signal.

So how do we solve this problem? What we need is a good breaking system like we described above, right? And as we just learned, the best breaking comes from having a high current capacity amplifier. So if the speaker tries to shoot past its mark, we have the maximum opposing force to damp its motion.

Make sense?

Thomas

Absolutely brilliant explanation! :clap:
 

drummerman

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Indeed but isn't current and cone control just one side of the story?

Aren't dynamic swings or headroom equally important and thats where volts matter?

regards
 

Craig M.

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367o3r.jpg
 
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Anonymous

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Besides all of the above mentioned comments (and I love the explanatoin about the pushing back speakers as well!!), one other important aspect is obviously budget and also where you are coming from .. My (simple) situation:

I've got B&W CDM7 se speakers (for about 12 years now). They have always been driven (as part of a surround setup) by a surround receiver (Always Denon so far, currently 3808 specced at 7x130W). I have never had any complaints about the sound. Untill the day someone came over with his power amp (Modwright 2x150) to 'show' how different that would be... Got to say it was an amazing difference. The speakers opened up especially in the highs, and at the same time much stronger base as well. Effectively I'd say that the sound was now much more in balance (between low/mid/high). Interesting result being that we had less urge to crank up the volume..

Meanwhile I have now bought a Parasound A21 (2x250W) and got it in my system for a week. Same result!!

So for me it is absoultely clear that just power spec on itself does indeed not mean a lot. The build, design etc but probably mostly the potential for high current is one of the biggest reasons for the improvement (the Parasound delivers up to 60 amp per channel).

So my short answer to your question would be: More current first, closely followed by more power:)
 

Soopafly49

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Thanks for all the great and interesting replies. Ill have to check all the specs out but I think im going to go ahead with monoblocking them with a preamp.
 

Soopafly49

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perthpete said:
Besides all of the above mentioned comments (and I love the explanatoin about the pushing back speakers as well!!), one other important aspect is obviously budget and also where you are coming from .. My (simple) situation:

I've got B&W CDM7 se speakers (for about 12 years now). They have always been driven (as part of a surround setup) by a surround receiver (Always Denon so far, currently 3808 specced at 7x130W). I have never had any complaints about the sound. Untill the day someone came over with his power amp (Modwright 2x150) to 'show' how different that would be... Got to say it was an amazing difference. The speakers opened up especially in the highs, and at the same time much stronger base as well. Effectively I'd say that the sound was now much more in balance (between low/mid/high). Interesting result being that we had less urge to crank up the volume..

Meanwhile I have now bought a Parasound A21 (2x250W) and got it in my system for a week. Same result!!

So for me it is absoultely clear that just power spec on itself does indeed not mean a lot. The build, design etc but probably mostly the potential for high current is one of the biggest reasons for the improvement (the Parasound delivers up to 60 amp per channel).

So my short answer to your question would be: More current first, closely followed by more power:)

How do I know if it has more current?
 

audioaddict

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i think the power in an amp issue is very interesting but i think in absolute terms as someone has already stated in this post is that it depends on many things, ie speaker sensitivity etc . another thing to consider is to tell the difference you would probably have to compare amps side by side ie a 100 w against a 40 w to see which suits you better as for instance the 40 watter may be of a higher quality design, although in some cases i guess, a bigger power amplifier could be the same as having a bigger engine in your car, you may get a bigger more comfortable ride. my mono blocs are probably too powerful in some ways as il never be able to give them a proper airing so to speak as they are to loud but the benefits of the mono blocs are the detail and separation of instruments and the transparancy, although im sure there are many lower output intergrateds that would outperform them in some or many ways.
 

audioaddict

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another thing i meant to mention is speaker amp matching, which is critical. all my previous posts you will read ive been in almost despair as my system was almost unlistenable at times after id spent a fortune ( my apoligies to plastic pengiun for doin his head in lol ) but now my speakers are a much better match for my amps the system is a dream.
 

busb

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CnoEvil said:
busb said:
Thanks for the suggestion. Their REF150S would do the trick & is class D with full switch mode PSUs for £1.5k.

The level of detail from the Primare was jaw dropping. The imaging through my Arros was sublime...<SNIPPED>

You give very interesting insight......and I agree with you about the quality of the amp.

The Bel Canto is the only Class D amp that I have liked, which is why I suggested it (great CDPs and Dacs as well).

A dealer rang me last Friday. He also stocks Bel Canto. He oppined that the cheaper Bels didn't even get close to the Primare. Loud & Clear in Edinburgh also rang back saying how good the Primare was driving Totem Arros & a few high-end speakers well out of my price range! The emerging consensus seems to be that the A34.2 is very ggod VFM at £2100 - it would have to be at that price! I want to read a review.
 

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