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.

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.

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.

Visiting an audiophile friend: Avantgarde UNO 2.1, KEF LS50, Tannoy 501A, and Spendor SA1. Merry Christmas & Happy 2020's...

[2020-01 - Update... The active Tannoy speaker was originally listed as the "401A". In fact it's the "501A". Text and graphics changed...]

One of the joys of writing an audiophile blog is the opportunity to meet some interesting people in this hobby over the years! Here in Vancouver, there's no audiophile special interest group or club I'm aware of. As a result, connections are made through receiving E-mails or private messages once awhile by locals to hang out, check out gear, and listen to tunes together...

After meeting up in person a few months back, I paid one of these local audiophiles (who shall remain anonymous :-) a visit at home to check out his main system:

As you can see, he's got quite the pair of speakers and clearly his wife is highly accommodating to his audiophile "needs" ;-).

MEASUREMENTS: Emotiva XPA-1L (Gen 1) Class AB Balanced Monoblock

Let's continue measuring some amplifiers I have here at home. Today, we're going to get a bit more serious with fidelity into the "audiophile" level. Of course I'm using the term "audiophile" here for fun since audiophilia often does not equate with high-fidelity; but who else uses monoblock amps at home except for audiophiles!?

Here's a single 35lb Emotiva XPA-1L "Gen 1" monoblock which I bought back in 2013, a few months after it was released. Far from the most expensive monoblock amplifier out there, costing a "mere" MSRP US$699 each:

This is one of two I have in use as my reference amplifier for many years now. There's not much to see on the rear - speaker outputs, both RCA and XLR inputs (toggle switch to select), IEC power connector, 12V in/out trigger (can daisy chain a few devices) and main power switch. In the front, we have the large round Emotiva switch to turn on from sleep mode, a single LED that turns red when running diagnostics or if there's a fault, and blue as above when fully on. Notice that there is a switch just above the etched serial number to set it to either "standard" Class AB mode or the special Class A high bias mode which is a selling point for this amp that we'll of course talk about. When the switch is toggled to "A", it operates at Class A for up to the first 35W into 8Ω.

Over the years, I have seen a couple of (p)reviews from Audioholics and The Poor Audiophile, but have not seen any independent measurements of the output quality.

From late 2014 until they discontinued this model (not sure when), Emotiva also made the "Gen 2" model which cosmetically looked slightly different with black instead of silver side trims. I believe internally they also made some changes which were more about cost-cutting than affecting the sound quality.

Redscape and Creative Super X-Fi Amp: Headphone Virtualization

Thought I'd take a little break this week from all the amplifier discussions recently and post on something rather different!

I enjoy headphone listening... But not as much as actual speakers in an actual room :-). I see headphones more as a tool for detailed listening, and will reach for them out of necessity when I'm on the road or for private listening. Otherwise, I would much prefer to be enjoying the sound from my speakers.

Beyond typical reasons such as comfort (no matter how comfortable, I'm just not a fan of things touching the ears or around the head), a big part of the issue is that headphones have never sounded natural to me. Subjectively, the "inside the head" sound, while I can get used to, just isn't an experience that I find particularly pleasurable. A reason I bought the Sennheiser HD800 a number of years back was because it was said that these headphones were capable of projecting sound so that the experience was more outside the cranium. Alas, if one is expecting any headphone to do this well, there will be inevitable disappointment; unless you're applying some kind of playback processing like crossfeed, the physics will not permit such a thing. As a result, I am intrigued by ways of making that head-fi experience more life-like which is what the products today can potentially do.

MEASUREMENTS: Onkyo TX-NR1009 "WRAT" AV Receiver Class AB Amplifier... Plus Pi / LP / Resolution miscellany.

I currently have 3 AV receivers here at home. The Denon AVR-3802 is my oldest machine, purchased back in 2001 and being used in the living room for stereo playback. My newer Yamaha RX-V781 (2016) is currently in use for movie playback with Atmos/dts:X decoding. This leaves the Onkyo TX-NR1009 (2011 model) that I bought used in 2013 which has actually been sitting unused for the last few years mainly because it's an older HDMI 1.4 device which did not support full 4K/HDR/60fps switching:

It's a shame because I think of the 3 receivers, subjectively this is probably the best sounding (no blind test done, just a suspicion), has the highest power rating (135W into 8Ω, 1kHz, 1%), THX Select2 Plus certified, can amplify 9 channels (9.2 decoding), and when new, was also the most expensive of the three. I'm sure at some point I'll find a use for this 41 pound monster - maybe if/when the old Denon breaks down :-).

I don't think anyone can fault the external build quality which also looks quite handsome. Onkyo did unfortunately have some electronics failure issues with this generation of receivers however and back around 2016, I sent this unit back to them for an HDMI board replacement (here's a thread on the issue a few years back).

For this post, I think it would be interesting to explore the sound quality of this device as a 2-channel amplifier (especially compared to the little Yeeco TI TPA3116 amp last week). It'll give us an idea of how well a good receiver could perform and give us a peek at a modern Class AB device sitting in the higher end of the consumer price ladder (Class AB receiver amplifier designs have not changed that much in the last number of years). These days a similar tier THX model with equivalent power would be the newer Onkyo TX-NR1030 and TX-RZ1100.

MEASUREMENTS: Yeeco TI TPA3116 Class D Amplifier (aka Nobsound NS-01G, Douk Audio F900S, Mogu F900S)

As I posted back in June of this year, we can get inexpensive little amplifiers these days based on Class D chips such as the TI TPA3116D2 (first released in 2012) which is what is inside the device here:

Yeeco TPA3116 amp being probed... Notice that input is through the AUX phono jack in front from the RME DAC.

As you can see, I have a "Yeeco" branded device but these are produced in China and will come in a number of brands like the Nobsound NS-01G from Douk Audio, and other names like Fac"Mogu" discussed in this review and here's Z Review with an older version.

I mentioned in the previous post that once I have the amplifier measurement rig going I was going to have a look at the output from this little amplifier. I figure this would be a good device to start with using the MOAR amplifier procedure described last time.

So what does US$30 buy us in terms of sound quality in 2019?!

The "Measurement Of Amplifiers Rig" (MOAR): Standard Tests, Loopback results, and the AMOAR Score.

While I'm not a huge fan of acronyms, sometimes one just needs to make something up for ease of reference; hence the "Measurement Of Amplifiers Rig" or MOAR ;-) for short to refer to this system which I'm going to attempt to characterize today:

Running loopback tests.

As you can see, it's a conglomeration of hardware components which will allow me to collect amplifier measurements relatively quickly and I believe with good quality results based on my own testing over the last number of weeks (in fact I've been mulling over much of this for months even before the Linear Audio Autoranger was fully up and running). A hobbyist project to be sure, and one that audiophiles and DIY folks can come up with variants of and try out.

Of course, a measurement system isn't just about bits of hardware but also the software that can be used, the thought behind various tests we can run, and most importantly, a standard procedure that can be followed to ensure that devices are measured consistently and can be reliably replicated here on my test bench and elsewhere with similar equipment. As with most testing, I wanted to find a way to quantify performance, consider what is reasonably "true to life", borrow from tradition for comparison purposes, as well as emphasize aspects I find important. Hence this post will hopefully provide adequate details around a "standard battery" for what will be posted here in the days ahead.

RETRO-MEASURE: Klipsch Forté I speaker impedance. (And it looks like Qobuz responds to Amazon...)

Well guys, I'm still working on the Autoranger amplifier test system looking at standardization of the measurement technique and settings which is a pretty big job still, so this week I thought I'd show you some data I grabbed a few months back while working on the speaker impedance measurements series (Part 1, Part 2).

Every once awhile, I'll drag up an old device for a quick measure. Previously it was stuff like my old Sony SACD player, or the old laser disk player. This time, I went over to my dad's place to have a listen and measure his main speakers - the Klipsch Forté (original first version) made back in the 1980's until the early 90's I think.

Front and Rear of Klipsch Forté from the 1980's. Note the large 12" rear passive radiator.

I thought it was good to have a look at this device since there's been buzz lately about the latest model Forte III (Stereophile review, Darko review, Darko bought a pair). Also, a couple years back I ran into this Stereo Review article by Julian Hirsch on these speakers from 1986 as an example of what SR tests looked like back in the day:

It's Alive! The Linear Audio Autoranger MK II...

And the kit is now alive just in time for Halloween the other night. :-)

For those still wondering what this is, you can check out Jan Didden's video of the Autoranger MK I from 2017 and his demo of how it's used:

On Audiophile Forums. Disagreements on MQA. (And Redscape preview...)

I thought for this post it might be good to talk about audiophile forums.

A couple weeks back, some of you expressed frustration with the Audio Science Review Forum, the opinions of the host there, and general MQA disagreement. Over the years, like probably many of you, I've had my share of participating in forums, disagreements with views expressed and the bickering at various venues. All in good fun however and nobody needs to get too perturbed... It's only a hobby, right?

I've read posters say that MQA is "the gift that keeps giving" :-). No doubt it's a topic that has provided for much discussion around here and elsewhere!

However future audiophile historians ultimately judge this time in our hobby, I think MQA will have its place as a controversy that divided the community deeply. I don't think this is a bad thing in that it has provided many opportunities for us to discuss and perhaps be enlightened by what is true vs. false, shown a divide between mainstream press with close industry ties vs. independents, objective vs. subjective testing, faith in (specifically one) authority of digital audio vs. skepticism. And this has played out publicly probably in its most dramatic fashion on audiophile forums these years.