Saturday, 25 January 2020

INTERNET BLIND TEST: Is high Harmonic Distortion in music audible? (plus Pet Shop Boys' newest, HRA needs HDR)

Another year, another Internet Blind Test, my friends! For me, doing this is important because it keeps us honest. It's worth reading this article in Audioholics published recently for an overview of the complexity of perception. I believe it's essential that audiophiles have an opportunity to participate in exercises of perception which I hope can enlighten ourselves and in aggregate, enlighten each other.

It's good to capture naturalistic data of audiophiles "in the wild" on top of information we may read from the "ivory tower" of Academia and profit-motive driven claims from Industry. Arguably, this is some of the most useful data. We can for example quite easily measure amazing levels of performance these days from our devices, but if we never correlate this to audibility, the data says nothing about relevance to humans, which at the end of the day is the only intent of these devices!

If you remember, last year we did the "Do digital audio players sound different?" test (the results systematically discussed starting here). This time around, in late 2019, Paul K [aka pkane] (who also wrote DeltaWave) contacted me to try out the early builds of his new software called "Distort"; aptly named software that allows us to purposely introduce anomalies into audio data. Among a number of distortions one could introduce is the one we've all heard off - harmonic distortion.

Saturday, 11 January 2020

MEASUREMENTS: Hypex nCore NC252MP Amplifier (+ Subjective opinions around objective testing, and CES2020)

Alright, you knew this was coming from the post last week with assembly details for this amp.

As discussed, this is an easily assembled single-board OEM Class D stereo amplifier rated at 150Wrms into 8Ω, 250W into 4Ω, and 180W into 2Ω. The enclosure comes from Ghent Audio. The amplifier is based on the Hypex nCore "phase shift controlled self-oscillating loop" design.

Let's run this box through my usual MOAR testbench as previously described and see what kind of data we get. In general for these tests, the signal path for measurements looks like this:
RME ADI-2 Pro FS AKM DAC (signal generator) --> XLR --> Douk/Nobsound NS-05P passive attenuator --> XLR --> Hypex NC252MP amplifier --> Test leads --> BNC unbalanced input of Linear Audio Autoranger MK II --> Balanced TRS/XLR --> RME ADI-2 Pro ADC --> USB --> Surface Pro 3 laptop
I'll also have some oscilloscope measurements where the test leads will be directed towards the oscilloscope instead of Autoranger and RME ADI-2 Pro.

Saturday, 4 January 2020

An Inexpensive Hi-Fi Class-D Stereo Amp for the 2020's: Hypex nCore NC252MP (DIY Assembly)

Happy 2020 everyone!

A few months ago, I saw this video on YouTube that got me thinking about just putting together an amplifier to start off the decade of the 2020's. That project in the video involved the use of Bang & Olufsen's ICEPower 200ASC and 200AC modules, good Class D amps which I agree should sound great and certainly a worthy project!

But I wanted something potentially even better. Let's put together an amplifier that should perform with even less distortion, somewhat higher power, and this can be done even easier because you don't even need to string two boards together! "Better" does come with a little higher cost, but not that much more.