Sunday, 28 July 2019

MEASUREMENTS: "Noisy" Switching Power Supplies vs. Lithium Battery Packs (12V battery with RME ADI-2 Pro FS & Topping D10 DAC results)

Perhaps we don't think about it much or give it enough credit. I believe one of the advances in the last few decades that has provided the foundation for technological progress we enjoy today is the lithium ion battery. Li batteries were commercially released in 1991 and since then, thanks to the energy density available, combined with increasingly efficient electronics, all kinds of things these days can run off battery power - cars being the poster-child of this advancement...

A few weeks ago, I showed the little Class-D amplifier system running off a battery. How about we try out my RME ADI-2 Pro FS on batteries:


What you see here is the device connected to the Talentcell 6000mAh 12V Li-Ion battery pack. Since the RME ADC has become my standard for measurements in the last year, I have wanted to make it "portable". Talentcell makes an even smaller 3000mAh 12V battery which would work fine. While a little larger in size and weight, the 6000mAh unit is still lightweight and will be able to power the ADC/DAC for >5 hours - enough for any recording and measurement I would want to do in a single sitting.

Tuesday, 23 July 2019

SUMMER MUSINGS 2: Multichannel and the audiophile. MCh streaming with a TV Box. And Thoughts on the Future...


Hope you're all having a great summer... I thought I should take the opportunity to respond to this comment from Steven on the blog post last time broadly and with more details:
Steven 8 July 2019 at 21:07 
What about surround sound? Some of us are into that stuff. ;>
It does change things slightly. USB and S/PDIF won't suffice for lossless 4.0/5.1/and beyond audio data. That leaves HDMI or analog, afaik.
Excellent points Steven.

Surround/multichannel playback is important and sadly rather neglected in the audiophile world. I saw recently that the TAS website posted this article on the "rebirth" of quadraphonic sound.

Hmmm, isn't this actually the "rebirth of the rebirth" of quadraphonic? As I recall, there was a rather significant thing among home theater enthusiasts and audiophiles called multichannel SACD and DVD-A around Y2K :-).

Saturday, 6 July 2019

SUMMER MUSINGS: "How Much Difference Does It Make?" - On Balance and Adequacy for audiophiles.


The other day, I was reading Jim Austin's "As We See It" post on Stereophile titled "How Does the Music Make You Feel?". A relatively sensible article putting forward his and the magazine's perspective around finding "balance" between the subjective and objective sides of the audiophile pursuit. I agree with the central thesis, ultimately it is a subjective decision how one wants to spend time engaged in this hobby based on the emotional effect of music (I hesitate a little to say "music" here because let's be honest, not all audiophiles are in it for the music - sometimes it's the "sound" that's being sought). Music is art and appreciation of art will always be subjective, perhaps even wildly idiosyncratically for each person. Nonetheless, it's not that simple is it if we "look at the forest instead of the trees"? Let's take a higher level perspective and consider the audiophile hobby as a whole, rather than the audiophile him/herself. Are there some principles we might want to keep in mind?

Remember that what I've called "hardware audiophiles" are actually the niche hobbyists Stereophile is speaking and advertising to. I don't think Stereophile is of much interest to the multitudes of "music lovers" who probably are quite happy already with decent bitrate MP3 streaming over cell phones. As discussed before, these two hobbies intertwine but IMO are not the same. In every Stereophile issue, while some pages are dedicated to albums, music reviews, or maybe interviews with artists, the contents mostly discuss hardware products used in reproduction of the music. Our emotional response to reproduced music is a combination of the artistry in the music and science of reproduction. The audio devices used have technical characteristics that are objective and can be measured. As an analogy, in the visual arts world, we might or might not subjectively like the Mona Lisa, but when we look at a reproduction (photograph or scan of it), we can certainly experience and measure the differences between high vs. low resolution copies, and we can comment on or measure other objective traits like color saturation, accuracy, brightness, contrast, etc. compared to the "real thing" under the lighting conditions at the Louvre.

In reading that article by Mr. Austin however, between the personal stories and opinions, I noticed that like in most editorials covering this topic over the years in magazines, it's side-stepping a very important dimension. Achieving "balance" is not just about the way it is done (subjective listening +/- objective measurements), but also about the depth of exploration from which we derive adequacy. In other words, it's not just about whether we subjectively look at a car/woman/man and be captivated by its/her/his beauty, or whether the thing/person is objectively faster/taller/shorter/skinnier, but rather, are these qualities "good enough" for our intentions?

Let's expand on this...

Saturday, 29 June 2019

LISTENING: Fully battery-powered wireless streamer & amplifier system (Yeeco - TI TPA3116D2, TalentCell 12V battery)


A few weeks ago, I read this review on an independent audiophile site about an inexpensive Nobsound Class D amplifier based on the TI TPA3116 chip. I was curious so I ordered an equivalent one off Amazon - the little Yeeco Bluetooth-capable amplifier shown above with box contents including the 12V power supply for <$US32 (for an even cheaper package, here's one without the switching power supply, <US$25).

As you can see, the reviewer linked above gave the product some positive comments on the sound. I was curious to listen and since we know that Class D amps like these are very efficient, how about we run the playback system - music streamer to amp to speakers - completely wirelessly and battery powered for a listen also?

Saturday, 22 June 2019

MUSINGS and LISTENING: On Absolute Polarity / Phase... (And on the joy of the modern audiophile.)

Hey guys and gals, I thought for this post we'll spend a bit more time on the topic of "absolute polarity". As you can see from the post last week in the comments, our man in Japan Yamamoto2002 posted a link to his page where he has an interesting test signal for all to listen to.

If we look at the test signal he used, it's an asymmetrical waveform where half of it appears to be a standard sine wave, the other half has been "flattened" off which results in numerous harmonics if we are to display it on an FFT. One of the files is simply the inverted version of the other to test whether this polarity change is audible. Notice that the waveform is bandwidth limited, and there is no "ringing" after going through a digital filter.

Saturday, 15 June 2019

MEASUREMENTS: Topping D10 DAC. (And a few words on "absolute polarity / phase".)

Hey guys, getting busy around here as I'm preparing for summer holidays coming up in a couple of weeks :-).

I did want to post a "quick" report however on the Topping D10 DAC (<US$90) I got last week... It's for an upcoming project of sorts which I'll post on over the months ahead. What I wanted was a DAC that could be powered off USB, reliable with Window and Linux compatibility, that's reasonably portable, and of course of high signal accuracy.

Notice the DAC manual shows some AP measurement graphs... I guess Topping believes in showing objective accuracy :-). Nice.

Saturday, 8 June 2019

GUEST POST: Why We Should Use Software Volume Control / Management by Bennet Ng. (Plus discussions on resampling options, true peaks, etc...)


I received an invitation from Archimago to write something about volume control. While I am of the opinion that digital and analog volume controls can coexist to achieve an ideal gain stage, this article is mainly about PCM digital volume control.

The basic conclusion we can say regarding digital volume control is that as long as the playback device has higher bit-depth than the file source, it is possible to losslessly reduce the volume of a file until the playback device's bit-depth limit is reached. For example, with an ideal 24-bit device, it is possible to playback a 16-bit file 48dB lower without losing quality, because one bit has about 6dB of dynamic range (the exact formula of bitdepth and dynamic range is 6.02*n-bits + 1.76).

Saturday, 1 June 2019

POLL RESULTS: Music streaming service adoption among audiophiles in 2019...

Click on image to zoom.
Yeah, I know. Music streaming as a subscription model is the latest "revolution" for music lovers. This is why I decided to put up the recent poll in mid-March while we were concurrently also running the blind test as reported on in the last few weeks. Above, you see the overall results based on the visitors to this blog.

Remember that for the poll, I allowed voters to select up to 3 options. As a result, even though there were 616 respondents, a total of 809 selections were made. This means that up to ~30% of people selected more than 1 option and these are represented in the percentages above.

Saturday, 25 May 2019

BLIND TEST Results Part 4: "Do digital audio players sound different playing 16/44.1 music?" - Subjective Comments. Final thoughts on blind testing and critiques.


As we close off discussions and posts around the Internet Blind Test of devices playing 16/44.1 music, I want to publish some of the subjective comments from respondents who undertook this test... Impressions in the respondents' own words about the test when they submitted their results to me.

Remember that these are subjective. Human perception, especially when differences are at the margins of our perception are of course tough to describe. And when we compound that with the limited utility of words to describe ephemeral experiences (even with codifying the terminology as was attempted years back), it's no surprise that meaning can often only be conveyed as impressions. It's great to see the respondents trying their best and in many instances, I certainly appreciate the impressive use of language to express the experiences. Let's have some fun with these!

Saturday, 18 May 2019

BLIND TEST Results Part 3: "Do digital audio players sound different playing 16/44.1 music?" - Listener Results.


Thanks for the patience everyone. We are now into Part 3 of the report on the Internet Blind Test on the audibility of 16/44.1 digital playback using various devices. In Part 1 we talked about the test procedure itself and unblinded the devices (ASRock Z77 Extreme4 motherboard, Apple iPhone 6, Oppo UDP-205 as ethernet DAC, and Sony SCD-CE775 playing a burned CD-R).

Last week in Part 2, we reviewed the objective measurements of the 4 devices. I hope the readership recognizes the importance of doing this to set the context of what we're looking at this time as we dive into the results from the blind test respondents. As with many things in life, it is only with having facts at our disposal first, then we can make comparisons and develop ideas based on this foundation of knowledge.

Saturday, 11 May 2019

BLIND TEST Results Part 2: "Do digital audio players sound different playing 16/44.1 music?" - Relative objective performance. [And a few words about "Legends"...]


Last week, I revealed the four CD-resolution / 16/44.1 playback devices I used for this blind test. (By the way, if you want to have a listen to the original 16/44.1 track excerpts used, I added a link as an addendum to the post last week.)

While I'm still doing some counting, calculations, and writing the summary of the data, I think it's best this week to start by having a better look at those devices and seeing what objective results tell us about them so we can hypothesize what we might find when we examine the blind test results.

While it may be controversial to some in the audiophile world, I think we should keep our minds open to the idea that science and technology for digital audio playback has already surpassed the human auditory system. As discussed years ago, the human perceptual and cognitive systems do not have infinite resolution. I'm of course not discounting that the ears and mind have excellent abilities when it comes to appreciating miniscule differences, yet I think we have to remain humble; even if we believe we have "golden ears". Also, even if we don't believe measurements capture everything, it's not unreasonable to accept that the vast majority of what is heard can already be quantified in terms of fidelity to the source. This is why I think we need to explore the objective performance first... Then we can see if the subjective preferences from the respondents line up with expectations. I think for many of the well-respected audio engineers that design our hi-fi gear, this sequence makes sense. Ensure that the measurements are decent first, then verify and tweak with subjective listening.

Over the years, I've measured most of these devices in the blind test separately with different ADCs. For this post, let's run each one through the RME ADI-2 Pro FS and compare objectively using the exact same "measuring stick". For completeness, here's what the measurement chains look like with each player/DAC:

Saturday, 4 May 2019

BLIND TEST Results Part 1: "Do digital audio players sound different playing 16/44.1 music?" - Devices Unblinded! (Plus unusual exuberance & bias in the media?)


Thanks everyone for taking the time and efforts in performing the blind test which we started back in late January!

I officially closed off my survey from submissions May 1st (I promised April 30th, but gave a few hours more for stragglers from different time zones). I trust the 3 months provided plenty of time for everyone who wanted to perform the test to do so. I'll leave the blind test samples available for download for now and will take the files down in the near future.

You can read about the reason I ran this blind test in the previous post, but in a nutshell it's because of this poll result which I think reflects general audiophile perceptions on the question: