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Hypex NCx500 Class D Amplifier Review
- Thread starter amirm
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That doesn't make sense.
The range can be 0Hz to 1mHz, it's irrelevant because the value plotted is for a specific frequency, at a specific impedance, at a specific power output. At those specific points, that is the THD+N value.
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THD+N depends on what bandwidth you are measuring over. The noise (N) component of THD+N greatly depends on what frequencies you are integrating noise over, the higher the bandwidth the higher the noise. For higher frequencies measurement bandwidth will impact THD as higher harmonics will be ignored if the bandwidth is too low.
Some examples illustrating this.
1 kHz test tone - 20 kHz bandwidth
1 kHz test tone - 45 kHz bandwidth
THD between the two is pretty much the same. 20 kHz bandwidth counts up to the 20th harmonic while 45 kHz bandwidth counts up to the 45th harmonic. However as more noise is integrated with the 45 kHz bandwidth noise is about 3 dB higher.
11 kHz test tone - 20 kHz bandwidth
11 kHz test tone - 45 kHz bandwidth
At 20 kHz bandwidth there are no THD components as the 2nd harmonic is at 22 kHz which is outside of the measurement bandwidth. With the 45 kHz bandwidth you get up to the 4th harmonic. As with the first example integrated noise is higher with the 45 kHz bandwidth.
Michael
Yes, Apollon announced this in April.Apollon NCx500ST listed. Possibly the cheapest assembled NCx500 in EU...
Hypex NCx500 ST NCOREx Stereo Amplifier
The Apollon Audio NCx500 Stereo Amplifier utilises the newest Hypex NCx500 amplifier module as its core. This exceptional technology provides abundant power and remarkable precision, making it an ideal choice for discerning audiophiles and professional studioapplications.apollonaudio.com
Apollon Audio Class-D Amp Build Quality
I think we surpassed the Purifi ref design with our Pure 12 1ET400A multichannel amp :cool: The buffer is not bypassed @12.8dB Gain
www.audiosciencereview.com
And surprisingly 644W into 4 ohms both channels driven even using a single SMPS1200.
Apollon Audio Class-D Amp Build Quality
read again :) Ok, is the difference ... got it. Sorry.
www.audiosciencereview.com
Read Michael's @mdsimon2 's excellent post. The bandwidth mentioned is the full bandwidth of the measurement system, not the narrow bandwidth around the test tone. If the measurement bandwidth is 20 kHz as in the Hypex spec, then the third harmonic (at 30 kHz) of a 10 kHz tone is already rolled off (reduced) by the low-pass filter before the THD measurement is taken. That will yield lower THD than if the third harmonic was included in the measurement. Reduced bandwidth for THD is more prevalent for class D designs IME due to their ultrasonic switching frequency, leading to inclusion of a low-pass filter on the amplifier's output. Note that most amplifiers include some sort of output LPF to reject noise and for stability, but they tend to have higher corner (roll-off) frequencies for A or AB designs, again IME.
Limited bandwidth is used more for noise measurements to improve stated SNR. A-weighted noise, following the ear's frequency response, is pretty commonly specified along with a wideband noise measurement.
HTH - Don
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Maybe an explanation between tone vs. bandwidth would help.
There's a thread discussing THD and IMD on ASR: https://www.audiosciencereview.com/...armonic-and-intermodulation-distortion.25436/
The test tone is the signal under test, e.g. a 1 kHz tone is a 1 kHz signal injected into the amplifier. A tone represents a single signal (amplitude and frequency). You measure the THD from a range of basically DC (0 Hz) to 20 kHz or some other upper bandwidth limit. The 1 kHz tone will have harmonics (distortion) at 2 kHz, 3 kHz, 4 kHz, etc. multiples of 1 kHz if the amplifier is not perfectly linear. If your measurement bandwidth is 0 to 1 kHz, rolling off everything above 1 kHz to -infinity (0 output amplitude), then THD will be -infinity (perfect) because no harmonics are measured by the test meter within the measurement bandwidth. Expand the measured bandwidth to 10 kHz, and now you get nine harmonics (at 2, 3, 4, 5, 6, 7, 8, 9, 10 kHz) included in the measurement, and THD will no longer be perfect but something less (for a real amplifier).
Going back to this observations. On the July issue of audioXpress Frank Veldman says:
"The aim with Hypex amplifiers has always been to have excellent performance across the entire audio band, for UcD and NCORE this meant distortion levels were practically frequency independent. For the development of NCOREx and Nilai this has been reconsidered and while extensive (listening) tests obviously showed the importance of proper high frequency performance, it did not necessarily lead to full frequency independence. For new developments this meant high frequency performance has been as important as ever in Hypex designs, the philosophy of what is happening below that changed to some extent. (...)"
I guess it kind of confirms my theory.
NC500
Indeed on NC500 "distortion levels were practically frequency independent".
NCx500
And that part "extensive (listening) tests obviously showed the importance of proper high frequency performance, it did not necessarily lead to full frequency independence" can be seen as prioritizing to reduce distortion < 5 kHz, where the ear is more sensitive and the music signal is stronger, while keeping the > 5 kHz around the same levels as before. Very interesting.
But then if the new Purifi 1ET7040BA can maintain the insane low levels of low distortion in all frequencies then it's the best below and above 5 kHz.
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Here is a plot showing how THD changes with measurement bandwidth. This is NOT a real amplifier! For illustrative purposes, all harmonics are -80 dB relative to a full-scale 0 dB 1 kHz signal tone. If the BW is less than 2 kHz, then THD is -infinity, off the chart (perfect). At 2 kHz bandwidth, we pick up the second harmonic at -80 dB, and THD jumps to -80 dB. The harmonic distortion does not add linearly in dB; you must RSS (root-sum-square) the harmonic signals to get the resulting THD. This means the plot is a gradually (logarithmically) rising line as you increase the measurement bandwidth and more harmonics are added to the THD level. By the time you reach 20 kHz bandwidth, the THD has worsened to -67 dB, without changing the actual harmonic levels from the amp but just increasing the measurement bandwidth to include more harmonics. In a real amplifier, higher-order harmonics would fall in amplitude until a certain high frequency is reached, then tend to flatten out, so the curve would not rise as rapidly. This is just to show how measurement bandwidth can impact the reported THD.
HTH - Don
HTH - Don
Philipp
Active Member
Shipping is free for Europe when you order over 200 €.
It is not, actually...
Philipp
Active Member
I see this in step two of checkout.
Sorry if I am wrong, i do not want to win an argument, this would be just generally great news.
Sorry if I am wrong, i do not want to win an argument, this would be just generally great news.
1% battery remaining? You are one seriously risk-disregarding mofo.
Philipp
Active Member
I have 5 kids, so its the same with me, even with 1% batterie left I still have to go on for ages ;-)
So my electronics better keep up or get replaced.
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ivo.f.doma
Active Member
It's not! Free only for countries near France. For example, when buying UMIK-1, the shipping cost for me was about €15.
Philipp
Active Member
Lucky me I live in Germany, toujours bien de vivre proche de la France!
DoesNotExist
Member
Apollon NCx500 Is 1090€ + VAT + shipping
https://apollonaudio.com/product/apollon-audio-ncx500st-stereo-amplifier/
To Italy Is 1400€ all included vs. 1490€ all included from Audiophonics
Thus, Apollon is the cheapest, at the moment, for the major part of EU countries
Lucky you.
I could not validate my order without paying for shipping, whatever the option I chose. Perhaps because your IP is from Germany.
If I am reading the cart numbers correctly, it seems competitively priced even for US buyers. (The version with standard buffer comes out to about $1300 shipped for me.)
On this forum, Apollon seems to garner praise for neatness and build quality. I also like the switchable balanced/unbalanced inputs. Almost tempted to take a chance that the NCx500ST won't ever need factory service....
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