Good post.
A little deeper on amp power please....
If somebody could elaborate on exactly how a higher watt amp will improve the sound of speakers (lower sensitivity speakers that “need” power). More specifically, I get that when the nature of the recording and the volume setting demand an immediate spike in power, an amp that delivers the spike will perform better than one that does not. But when I used to have an amp with output meters, it would be in single digits for most normal listening, and I don’t recall what a spike would have been - I want to say 15 or 20 watts. What I am scratching at is whether there is something more to power, i.e. the notion that the effortless power of, say, a 300 watt amp would somehow be an improvement over an otherwise similar 75 watt amp…even if a spike is just 20 watts. Hope the question make sense.
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+1 @carlsbad2 @8th-note @erik_squires Glad that current delivery came up soon here. Although many other factors reside in dynamic response, current capability and response to impedance dips seem to rise to the top in my experience. Factoring in that all speakers are different in how they behave with any given amp or amp topology, that the type of music is also a factor, even cable guage for that matter. But there really are so many things that can occur differently between systems of higher power with lower sensitivity and those with lower power and higher sensitivity. Even if dynamic response can be noted as similar in any given section of music (with volume matching), there can still a difference in tonal character and decay. There are reasons why many gravitate toward low power, high power, or something in between. But what seems to remain constant is that need for sufficient headroom, at least relative to the needs of any given listening environment (types of recordings, near field or large area etc.). |
I think that in addition to power, there's the issue of feedback vs. output impedance. By using massive output stages (relatively) you reduce the need for feedback to achieve low distortion. This tends to only work with high power amps, but surely not all of them. I suspect that a lot of what we think of as the need for power is really the need for high current, and that with ideal 75-100WPC amps with many output devices and low feedback we'd be very happy. |
@8th-note If I can add to that:
@erik_squires Current cannot exist without power and vice versa. So if the amp can make the power into the load, it can also make the current. There are a variety of issues with feedback. One is that the feedback node (where the feedback is applied in the amplifier design) usually is non-linear, meaning the feedback signal gets distorted prior to doing its job. This usually means additional distortion generated on that account, which is mostly higher ordered harmonics (and so IMD as well). That is part of why feedback has gotten a bad rap in high end audio, but its not feedback's fault so much as shoddy execution. The second problem is most amplifier designs lack the gain bandwidth product to support the amount of feedback being used as well as the gain of the amp. The result of this is that above a certain frequency, distortion increases. IME this phenomena is highly audible. Most THD measurements are made at too low a frequency to really show what is going on, but distortion vs frequency shows this problem with ease. Class D offers a way around both problems. I think that is why there are class D amps now that are shutting down class A solid state designs for sheer musicality. |
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