Can some one please clarify the following for me. When a amp says, for example, "150 watts per channel into 8 ohms and 300 watts into 4 ohms" what does this mean in ldiot terms (as little techno babble as possible please). Does the amp sense the speaker impedence and double the power? Also i read that a low impedence usuall means that the speaker is harder to drive but if you have one of these 150/300 watt into 8/4 ohms amplifiers does this mean the amp will chuck out more power for a 4ohm speaker thus driving it better? Or am i just talking nonsense?
Amplifier wattage rating.... please explain
- Thread starter SHAXOS
- Start date
No, it's a simple application of Ohm's Law - as impedance reduces, more current flows in the circuit, provided the amp has enough oomph to deliver it.
Problems arise with speakers of low impedance and amps without the guts to drive them - in very simple terms, power can flow out of the amp faster than the its power supplies can replenish it.
So the amp isn't actually sensing anything and delivering more power - it's simply behaving as it should in an ideal world.
See more here.
Problems arise with speakers of low impedance and amps without the guts to drive them - in very simple terms, power can flow out of the amp faster than the its power supplies can replenish it.
So the amp isn't actually sensing anything and delivering more power - it's simply behaving as it should in an ideal world.
See more here.
Morning Shaxos. As I understand it amplifiers (normally) increase their output into four/two ohms though normally 'sag' into very low impedence and protection usually cuts in at just below two ohms. Very stable amplifiers (or Class D 'digital') have limited dynamic headroom. They dont need it and d/headroom is just a way to make up for a compomised power supply though there's an argument that dynamic headroom or the power an amplifier is able to deliver into given loads at short bursts is arguably more important than an 'unconditionally' stable supply which doubles or at least increases significantly as impedance halfs. I'm not sure which one is better to have but these days most speakers use 4 ohm bass units so the higher figure is normally what you get in power. Bottom line is you can't have to much power though personally I have to say I have heard dire big amps which seemed slow and ponderous and small ones which appeared dynamic, powerfull and fast. As always, implementation is just as important as whats in it. I also like certain valve amplifiers some of which measure diabolicaly yet sound divine.
Cheers for the replies drummerman and Andrew, The reason i ask is that i got offered a funded PhD and will have a bit more disposable cash on hand which means ive got the upgrade bug...again. I recently had a problem with my neat motive 2 so they have been sent back but i did absolutely love them. Also will be moving to a larger room so thought an upgrade would be welcome as the neat 2 are small. I am considering an upgrade to the motive 1 or even the momentum 3i if funds allow. But i read from the specifications that the motive 1 has a lower impedence value and i was worried that my amp ( bel canto pre3 and s300) would not be able to drive them as well as they have the motive 2.
Once again thanks for the reply!
Once again thanks for the reply!
[quote user="paktongko"]sorry for silly question....."100w into both channel" means "50w per channel" rite?[/quote]
No. The way you stated it its 100 per channel. Regards
No. The way you stated it its 100 per channel. Regards
As well as seeing the nominal impedance figures you really need to see a graph to see how it varies, which good mags do - measure it themselves. I've seen plenty of speakers that are rated at 8 ohms but dip below 4 ohms at times. I think it was the Kef iQ5 that caused a lot of problems flicking a Rotel R06 into protection mode.
[quote user="darrenwm1"]you really need to see a graph to see how it varies, which good mags do - measure it themselves.[/quote]
Are those the same magazines that don't provide forums like this on which you can express your opinions?
Are those the same magazines that don't provide forums like this on which you can express your opinions?
[quote user="Andrew Everard"]Are those the same magazines that don't provide forums like this on which you can express your opinions?[/quote]
That'll be the ones. He's got a point though. Most manufacturers quote those totally meaningles figures, usually 8 ohms flat or, if you're really lucky it might say minimum impendace whatever ohms and they're usually still hopelessly optimistic. There are exceptions as always where you get some idea on what to expect but most of the time the only accurate way is to listen with the intended amp. The best way to judge a speaker anyhow but sometimes its good to know why something does'nt quite gel. I bet the inexperienced punter (or hifi salesperson!) would point the blame everywhere else first but the speakers. So I think graphs/technical explanatins even though they're not the sole deciding purchasing factor are a good/helpful addition to a review.
That'll be the ones. He's got a point though. Most manufacturers quote those totally meaningles figures, usually 8 ohms flat or, if you're really lucky it might say minimum impendace whatever ohms and they're usually still hopelessly optimistic. There are exceptions as always where you get some idea on what to expect but most of the time the only accurate way is to listen with the intended amp. The best way to judge a speaker anyhow but sometimes its good to know why something does'nt quite gel. I bet the inexperienced punter (or hifi salesperson!) would point the blame everywhere else first but the speakers. So I think graphs/technical explanatins even though they're not the sole deciding purchasing factor are a good/helpful addition to a review.
... or you can buy an active speaker system. All the guess work's taken out of it
Darren, give me a few days and hopefully we can sort something out. I'd like to listen to your 9's if possible.
Darren, give me a few days and hopefully we can sort something out. I'd like to listen to your 9's if possible.
[quote user="drummerman"]
... or you can buy an active speaker system. All the guess work's taken out of it
Darren, give me a few days and hopefully we can sort something out. I'd like to listen to your 9's if possible.
[/quote]
Please post your findings. Genuinely intrigued as to how they sound.............
... or you can buy an active speaker system. All the guess work's taken out of it
Darren, give me a few days and hopefully we can sort something out. I'd like to listen to your 9's if possible.
[/quote]
Please post your findings. Genuinely intrigued as to how they sound.............
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