@georgehifi ....thx! Yea, I've seen that video and specs when I was researching some Proton amps. Mind boggling! A tech with 40+ years exp had told me about them when I was looking for info on the Dahlquists. Said he'd owned several sets and had powered them with Bryston, Carver, PL and the Ampzilla. Said the Proton sounded better than any of them. I figured since we're talking low power, high current....I'd ask. Appreciate the info
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?
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I've never heard one of these, I like that they used Bi-Polars (BJT's) to achieve this performance into low impedance's as complimentary mosfets would have trouble doing these sort of figures. While a neat idea, I question the lower voltage rail, then high voltage rail used when even wattage is required for transients or louder passages, as the "sound" characteristics of those output transistors will be different for those two voltages used, I don't know if this is easily detectable while listening or not. Cheers George |
Most tube amps don't have "guts" in the bass due to low damping factor. You may prefer that or you may not and that will be room / speaker dependent.Bandwidth also plays a role, as well as the match between the amp and speaker. You can have an amplifier with very low damping factor that plays bass great, with plenty of guts. If that's a tube amp, just put it on a 16 ohm load rather than 4 and see how gutzy it gets! Current is just as important if not more than wattsThis statement is a common myth and is false. Current cannot exist without watts; they have a simple mathematical relationship. 1 Watt = 1 Volt times 1 Amp; its that simple. So if an amplifier has the 'current' it will also have the watts- they go hand in hand. Where we consumer only have wattage then we can not know much of each component the amp gives for example get 100 watts.The issue is speakers being matched to amps and this is a historical problem. Most speakers these days are meant to be played on an amplifier that acts as a 'voltage source' which is to say for a given output voltage, that voltage is invariant with regards to load impedance. No amp can actually do that but many can do perfectly well on most speakers but not all. But to further complicate matters not all loudspeakers are meant for voltage sources and these speakers will not sound right unless they get an amplifier that matches them. Some examples of loudspeakers of this type are ESLs, many horn loudspeakers, many full range single-driver loudspeakers, some box speakers both acoustic suspension and bass reflex. So you have to know the intention of the designer! For more on this see http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php With regards to low impedance, in the world of high end audio one of the main goals is to get things to sound real. To this end amplifier distortion is a huge deal because it is distortion that are the differences we hear in amplifiers. Higher ordered harmonics are interpreted by the ear as harshness and brightness even in very small amounts (as our ear has to be keenly sensitive to those harmonics as it uses them to determine sound pressure). Lower orders (2nd-4th) contribute to 'warmth' and 'body'. The ear converts all forms of distortion (THD, IMD, aliasing) into tonality. With most amplifier topologies it is not possible to add enough feedback in a way that prevents the feedback itself from contributing to higher ordered harmonic distortion. This is at the root of the tubes/transistors debate; the way the industry has gotten around this problem (insufficient gain bandwidth product) is to use an old technique known as 'lying'. They simply don't measure the amps at frequencies where we can see what happens in the range where the ear is most sensitive (Fletcher Munson) so we never get to see the real score. This is why there are amps with no feedback at all and consequently much higher output impedances. The idea with such amps is that tonality caused by distortion can be more important to the ear than actual frequency response errors. Good luck finding all this out on a simple spec sheet. |
Optimize, yes we do know what you are asking if say they give a spec into 8, 4 and 2 ohms which many do..No they do not. No manufacturer what I have seen have been given what ampere (current) spec into 8, 4 and 2 ohms. Only wattage and maybe the distortion. We are in the dark of how much current (and voltage) there were when we got the power (wattage). Internet know hows and reviewers say now and then. "The speaker X need a high current amplifier".. How would they know?! They do not have any other specifications that we all get.. There is specific amplifier designs that are primarily designed to be current sources. So they can have relatively low wattage but for producing that wattage it gives high amount of current and low voltage.. Or are missing something here? Were is the ampere and the voltage in the specifications? |
Class-D and complimentary mosfets poweramps fall down miserably when asked to deliver current into 2ohms so they can double the wattage all the way. That's why they never advertise "true" independently tested 8, 4, 2ohm wattage's just before clipping, because the 2 usually goes backward in wattage, indicating sever current starvation or limiting. Cheers George |
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