Technics SU-R1000 - Good but not the king of switching amps
Was looking at the measurements for the Technics SU-R1000 Integrated published by Stereophile. I never bother with the reviews of the sound quality as there’s 1 reviewer there whose ears I trust and it’s not this reviewer.
To be clear, this IS a digital amplifier, and is not a Class D amplifier. Atmasphere will always disagree with me, but given Technics nomenclature and the use of an A/D converter, and PWM output I think if any amplifier qualifies as digital this one does.
What I find kind of interesting here is that the measurements are OK but not absolute Class D killing results. I am particularly unimpressed by the performance of the impedance compensation circuit, LAPC, which at the end of the day does not seem to have performed significantly better than actual, non GaNFET amplifiers, particularly in removing the effects of the output filters Class D amps require. I really hoped to see a huge win here... but it’s not. It’s just making the PWM perform almost as good as a true Class D amplifier.
I have not heard this integrated, but the claims and expectations laid out for the technology seem to not be proven in the measurements. This is a very expensive integrated that does everything differently, and measures about the same as previous generation, also excellent sounding, Class D engines I’ve seen measured.
My stance that Class D was already very good and that new, faster switching amps would have to be truly spectacularly better to unseat them remains, in my mind, uncontested.
Can’t wait to see everyone trashing Class D on the measurements suddenly decide that this amp should be heard and not measured.
@erik_squires Yes, it seems as if the speaker correction thing is a sort of feedback system of its own. But it shouldn't have to be something just for class D. I've been trying to sort out if you even need something like that- audiophiles haven't for decades. |
@erik_squires I think most of that came from the George guy who used to post here quite a lot until recently. Personally I can't think of a good reason to switch at such a high frequency and I can think of plenty of good reasons to switch at a lower frequency. If you were trying to get a lot of loop gain, switching that high might be an advantage, but that doesn't seem to be what they are up to. One thing that is problematic is dead time- that is a fixed value for a particular output device. The faster you switch, the greater the percentage of the total time winds up being dead time; a slower switching speed can allow for lower distortion. |
Lol!! I won't always disagree, unless you say something like this- on the one hand, its a digital amplifier; on the other you discuss class D amps- including Pulse Width Modulation, which is an analog process found in most class D amps. I'm puzzled by the idea of a 'digital amplifier' since the bits in a digital word represent a voltage, whereas in a switching amplifier the on and off states have no such meaning. At some point the digital signal has to be converted to analog; as best I can make out this might describe a class D amp with a DAC driving it directly. I've puzzled over their claims about this amp. I think a lot of it is marketing. I've seen claims that the amp is zero feedback and there is also evidence to suggest that there is feedback. The output impedance of the amp should be very low even if its zero feedback and so should behave as a voltage source even into 2 Ohms. But that means that the output filter will introduce phase shift; to get around it they have a very high switching frequency and thus also a high filter frequency. At least that's my take on it. Its quite a tour de force of engineering- too bad it didn't bring home the bacon for you.
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