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Hypex NCx500 Class D Amplifier Review
- Thread starter amirm
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I'm sure I can deal with it and and throughly enjoy and love my music. But that's not the point.
The "wonk" part of me wants to see what's going on, particularly now, in a "paradigm shift". The "S" in ASR.
The IM issue crops up time and time again. Tweeter, tympanum, whatever. It's difficult to find hard data.
Economies of scale. Unitary price drops. Mass production of items used broadly across the range. The more the better./\ the obvious still leaves me \/
without an answer to my question.
"Higher parts reuse = lower costs"? If the majority of use cases would be for a minimum of stereo; then, would the re-use of the same smps for both channels be more relevant and lower costs? Less parts usage also includes the enclosure, and other common piece parts to be shared between L/R.
MyCuriosity
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Great performance. Will be nice to have square wave measurements as well
What does square wave measurements tell that FR measurements don't?
Unless band-limited, it shows the carrier wave that a 100 kHz FR won't show, then comes the usual "look 'Ma, it's oscillating, class D cacapupu"
MyCuriosity
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The frequency response represents the amplifier’s bandwidth and linearity across the hearing band. The square wave effectively tells you how the transistors respond to a perfect square wave. Are two useful but different things. I just thing that square waves will be a nice addition to the comprehensive set of measurement performed
As well as what others have indicated a square wave also gives a indication of the capacitive reactance, the inductive reactance in the circuitry, the slew rate and as well as frequency response if one calculates from the slope the bandwidth.
Why does it matter how the transistors (or any other component for that matter) responds to a perfect square wave (that doesn't actually exist)?
The frequency response tells you the same things.
From ancient days, I like to see the response to a band-limited square, e.g. 100 Hz or 1 kHz limited (filtered) to about 100 kHz. Analog sources can do that, intentional or not, and higher sampling rate digital systems (e.g. 192 kS/s with 96 kHz Nyquist). I don't think anyone is arguing for an "ideal" square wave. The main thing I am curious about is the slew behavior, does anything bad happen, and recovery (how fast, how clean). Simple frequency response sweeps, especially limited to 20 kHz, may not show a problem with slew recovery or stability. You need well beyond 20 kHz bandwidth to support low distortion at (and well below) that frequency, so checking the step response with a square wave is something I "always" did when I had stuff on the bench. Most of the time the response was benign, but every now and then something really ugly happened.
One catch is defining a load, particularly the reactive part, if you want to go beyond just a resistor. It was common to add a 0.1 to 1 uF capacitor across the load resistor but back then I did not have a wealth of speaker impedance plots so used what folk e.g. in Audio suggested (I miss Feldman and the other techies from back then...) The end game would be something like the Power Cube, natch.
But just a step into a resistor can be interesting, sometimes...
I think @amirm 's position is that is testing has not shown issues so it is not a worthwhile test. May be, hopefully is, true these days. But the old Missouri mule in me still says "show me".
IME/IMO - Don
One catch is defining a load, particularly the reactive part, if you want to go beyond just a resistor. It was common to add a 0.1 to 1 uF capacitor across the load resistor but back then I did not have a wealth of speaker impedance plots so used what folk e.g. in Audio suggested (I miss Feldman and the other techies from back then...) The end game would be something like the Power Cube, natch.
But just a step into a resistor can be interesting, sometimes...
I think @amirm 's position is that is testing has not shown issues so it is not a worthwhile test. May be, hopefully is, true these days. But the old Missouri mule in me still says "show me".
IME/IMO - Don
That's it.
MyCuriosity
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Because it is an indication how it will respond on actual signals.
Is it? Wouldn't actual signals be better?
What’s with all the grey silicone around the Wilma caps and electroytic caps. Is there some kind of vibration going on at these high switching speeds or something else ?
I can see the need if it was placed inside a sub woofer amp enclosure but that’s not the case here ?
Keeps them stable in shipping and in case of dropping, falling I think.
To prevent breakage at the lead legs and reduce vibration.
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