MUSINGS: The hunt for -150dB THD with the Victor's 1kHz Oscillator; A look at Paul K.'s Multitone Loopback Analyzer; And the pinnacle of audio streamer pricing? The Wadax Atlantis Reference Server.

I like a good challenge ;-). A few weeks ago, in my post on the E1DA Cosmos APU, in the comments, MG discussed achieving THD -155dB on the Victor's Oscillator! In my original post, I showed a picture of -141dB. Subsequently, I then fiddled around with the set-up and achieved around -148dB.

Well, on one of my lazy afternoons, I thought I might as well give this another try. The aim - at least THD of -150dB. So I packed up some parts I needed and moved it into the quietest room (electrically and acoustically) in my house. Bits and pieces laid out on my ottoman where I place drinks on late night listening sessions. ;-)

Clearly this would have to be run off battery power to remove any mains hum. I went with my trusty RME ADI-2 Pro FS ADC, powered by a 12V/8300mAh TalentCell lithium battery pack for convenience in case I needed to fool around with input voltage settings. The E1DA Cosmos APU was powered with a 5V battery pack.

A Look at ADC Noise Limits and Distortion - Or "How much difference does the Cosmos APU make?" And a look at 2-channel Room EQ Wizard measurements!

I received a few questions as a follow-up to last week's post about the E1DA Cosmos APU basically around the question: "When do I need a pre-amp/notch filter like that if I have a high resolution ADC?"

That's a great question! Let's spend some time looking into this...

Now, the first thing to be mindful of is that our DACs and ADCs are not perfectly linear devices, nor have limitless low-noise performance of course. This is why we measure the limits of DACs to gauge the extent of "accuracy". And ADCs likewise have limits as well to their intrinsic noise level and potential for distortion. As we approach the limit of the ADC's performance, it will start introducing its own characteristics into the captured signal which could look like noise anomalies as well as harmonics - like DACs, there is an ADC THD+N.

In this post, let's run some practical "experiments" of sorts using the Cosmos ADC and RME ADI-2 Pro FS to examine these ADC limits when measuring DAC dynamic range and THD+N/SINAD with and without the aid of the Cosmos APU.

EARLY LOOK: E1DA Cosmos APU - high performance, low-noise pre-amp and 1/10kHz notch filter. [Quick peek - S.M.S.L. DO100 DAC.]

Readers on the blog will likely remember that last year, Ivan Khlyupin (aka IVX on a number of forums) of E1DA sent me a pre-production Cosmos ADC for testing and use. As discussed then, this affordable ADC unit turned out to be a remarkably capable device using the ESS Sabre ES9822Pro chip at a very reasonable price. With recent price upheavals, currently on Amazon for a Grade B device with SNR 127+/-1dB(A) in mono mode, it's selling for just less than US$250.

There were already discussions last year that the "Cosmos" line of devices would include the one we'll be talking about today - the Cosmos Analog Processing Unit (APU). As the name implies, this is an analogue device that serves the purpose of (pre)amplification with very low noise, also providing a 1kHz notch for accurate measurements of THD+N/SINAD as we typically see in DAC reviews.

With the APU near production release (possibly next month or so), Ivan again kindly sent me a unit for use here on the blog. Using the combination of Cosmos APU + good ADC (doesn't have to be Cosmos ADC), the user should be able to peer down into the noise limits and measure characteristics like dynamic range, and THD+N/SINAD with great accuracy even beyond the limits of modern state-of-the-art DACs.

DEMO: Software de-clipping of dynamically compressed recordings (Red Hot Chili Peppers' Unlimited Love). On "Why you can't trust audio measurements". And "Those Obscure Objects of Desire" - Utility and Luxury.

Let's get right to the heart of the issue with the diagram above!

There have been discussions among audio sites like Audiophile Style and Darko Audio that this latest album from RHCP - Unlimited Love (2022, average DR7) - is their most "audiophile-friendly". 

Flea, the band's bassist, tweeted on April 1st (hope not meant to be April Fools' joke!):

“For you audiophiles out there, the new RHCP record is mastered directly from the tape we recorded it on, no computers, no lame compression or limiters”

In the image above, I extracted the last minute from track 1 ("Black Summer"), a portion of the music which is quite loud for a peek at the waveform. One look at the original data clearly shows that the music has gone through a compression step at some point in order to create that "flat top" DR5 in the image above. Flea is wrong.

Whether this happened in the recording, mixing, or mastering steps, who knows. The clear use of dynamic compression is present in both the 24/96 version and on the CD. Clearly, music like this does not benefit from the "hi-res" 24/96 version so I would recommend saving your money if you're tempted to purchase a download. As usual, be critical when buying hi-res.

REVIEW / MEASUREMENTS: CCA (Clear Concept Audio) C12 IEM - 1 Dynamic + 5 Balanced Armature Drivers - are more drivers better? (Plus new analogue disc technology, cable-maker Russ Andrews interview.)

Earlier this month, as I was preparing the final write-up for the KZ ZSN Pro review, I was impressed enough by the performance of those very inexpensive IEMs (less than US$25) to go ahead and grab these CCA (Clear Concept Audio) C12 (US$50) earphones to see how an upgrade at twice the price would perform in both listening and measurements. Note that CCA is a related company to KZ so when we look at the open-box image above, we see that the contents are similar. We have this time a braided ear-loop cable (that's still easy to get tangled), also 1.2m in length, a couple of info pamphlets, 3 extra sets of silicone ear pieces, same as the KZ ZSN Pro.

At twice the price of the KZ, the hope here is that these would represent a significant sonic upgrade across a number of domains. On the surface, a major talking point for these headphones is that they consist of a more complex arrangement of drivers which in theory could provide more accurate coverage across the audible frequencies. Drivers in each earphone include a single larger 10mm dual-magnet dynamic/moving coil driver, and 5 small balanced armatures (two of which are reported as Knowles 30095, not sure the others). So that's a total of 6 drivers per ear piece, 12 both sides - hence "C12".

 

MUSINGS: Myths, clichés and Hi-Fi+'s Taiko Audio SGM Extreme computer review. A hypothetical fast, fanless audio computer build. And "channels/bit-depth/samplerate" labeling convention - a suggestion.

"Nowadays people know the price of everything and the value of nothing."

-- Oscar Wilde, The Picture of Dorian Gray, 1890

Once awhile, we in the audio world run into devices that are so ludicrous that it becomes somewhat entertaining reading or watching reviews about them. Like Super Bowl ads, the advertising can be fascinating in themselves regardless of whether you care about or even know how to play American football. The Dutch Taiko Audio SGM Extreme is such a product which I find fascinating - not because the technology is all that mind-blowing (server CPUs, Optane storage, large SSDs, big fanless case) - but in seeing what they're trying to do with the "spin" around the product to try to justify an asking price! (Previously, I've referenced the device in a related discussion as well.)

I thought it was interesting reading this recent Hi-Fi+ review by Alan Sircom and examining the claims. Just because a review might be written in a "subjective" fashion doesn't mean readers can't or should not be critical about the beliefs expressed. To a certain extent, I believe it is the responsibility of "rational audiophiles" to push back against the nonsensical, even mythical, ramblings of certain subjective, supposedly honest, viewpoints. I agree with T.S. Gnu, typically we cannot expect magazine writers to be bluntly honest in today's environment.

For those unaware, The Absolute Sound (North America) and Hi-Fi+ (UK) are glossy, subjective-only, sister publications that IMO read like the unabashed advertising arm of the "high end" industry. Over the years, TAS & Hi-Fi+ have advocated snake-oil of all sorts and TAS even published pseudo-science articles purporting to be empirical research (look up the articles from Charles Zeilig and Jay Clawson around 2011 - I've mentioned this back in the day, and here's an example of what they do/say).

REVIEW / MEASUREMENTS: KZ ZSN Pro - very inexpensive dynamic + balanced armature IEM. (And the importance of the audiophile "low end" and meaningful succession.)

Since I believe much of high-fidelity audio is already "mature" technology, these days a lot of what I find interesting are products that either present new features for the music lover (and audiophile), or devices that are of high value. In a present era of inflation and energy price shocks, "value" I think for most people has become even more important into the foreseeable future. As discussed in the past, the price of luxury items is usually a reflection of non-utilitarian benefits rather than actual sonic fidelity; that is basically the epitome of the "high end" moniker, behind which, much snake oil is allowed to thrive.

In this post, let's have a look and listen at an IEM which I think absolutely represents a member of the "high value" class of products! At less than US$25, the KZ "Knowledge Zenith" ZSN Pro IEM is at a price point that anyone can afford if you're in the market for some wired headphones these days (funny the designation "Pro" for something in this price point!). Considering the wide range of prices for headphones, it's the kind of thing you can throw in your travel bag and not worry if they get damaged.

The question of course is how do these sound!? Let's take a deeper dive into this...

MEASUREMENTS: 1MORE Quad Driver IEM (E1010)

For the post this week, let's have a look at the 1MORE Quad Driver IEM (~US$150 these days). These have been out for awhile; released in mid-2017 I believe. The specs on these are quite interesting given the asking price. Driver configuration seems complex with single dynamic driver and 3 balanced armature units within the relatively small capsule. The dynamic driver is advertised as being some kind of "diamond-like carbon" (DLC) that covers bass and mids with the balanced armature units filling in at the higher frequencies based on the advertising material.

Furthermore, the headphone also has an integrated volume/playback control as well as a microphone when making calls.

The brand also prides itself on this being the world's first "THX Certified Headphone". I'm not sure exactly what that certification means; presumably some combination of testing to ensure low distortion and frequency response thresholds must be in the mix.

DEMO: Tears For Fears - "No Small Thing" - Low-DR CD vs. Higher-DR Steven Wilson 5.1 Downmix to 2.0 (and the obvious importance of audio production quality)

Despite all the examinations of what often amounts to subtle differences in sound when we compare different hardware devices, I think as audiophiles we too often neglect the very significant differences that mixing and mastering makes.

Recently, I received my copy of Tears for Fears' The Tipping Point, the Blu-Ray only available for order online here. As you can see in the image above (screenshot of the menu), the disc includes both lossless DTS-HD Master Audio 5.1 and Dolby TrueHD-Atmos mixes done by Steve Wilson.

I believe you can already stream the Atmos mix over Apple Music "Spatial Audio" but that would be in lossy Dolby EAC3+Atmos. As you can imagine, the multichannel mix sounds quite different from the 2-channel CD/lossless stream!

MEASUREMENTS: Topping HS01 - USB 2.0 Isolator & Ground Loop Eliminator (and a listen to Santana's "Blessings and Miracles")

Hey everyone, as you might be aware, I'm not a fan of USB "doohickeys" in general use. You know, all those USB boxes that are supposed to clean up your signal, or maybe reduce jitter, or "regenerate" this and that. Especially if you're not sure if you actually need it; some of these devices cost hundreds of dollars. On the lower price end, I had a look at the AudioQuest JitterBug FMJ last year which was a rather disappointing product.

Having said this, there are devices that can provide benefits like USB isolation for things like DACs. For example, the USB1 inexpensive ADuM4160 devices like this Nobsound ADuM4160. The problem is that this is only operating up to USB1 12Mbps "full speed". Furthermore, one would be limited to 24/96 performance even if the device is able to fall back and negotiate as USB Audio Class 1.

Enter the Topping HS01 (~US$70), a little black metal USB2.0 box advertised as providing galvanic isolation (to 1kVrms), for data and power lines with USB-B (to computer), and USB-A (to audio device) ends. Furthermore, there's a USB-C plug for devices that need extra power.

[Note: This device is not compatible with USB1.0/1.1. So don't be plugging in keyboards and mice to this. Non-audio devices like USB2 memory sticks and even my smart phone were fine. I have not tried plugging a USB2 hub up to this point so there might be issues there.]

MEASUREMENTS: Etymotic ER-4B - "Classic" In-Ear Monitor (IEM) / "Canalphone".

Nice box with accessories. Can't see it well in this picture but in the middle of the box is a small container of "damper"/"filters" and tool to aid in replacement when clogged.

Today, I want to expand the measurements of headphone-type devices to include examination of in-ear monitors. As usual, before posting measurements on a range of devices, I believe it's important to set the ground work as to how it's being done and to what relative "standard". I believe this is useful because when I use subjective descriptions, I think it's always nice to refer to context on the objective side. I have seen numerous reviews use things like star ratings or sometimes seemingly arbitrary "3.5/5"-type scores, but without more concrete, specific examples, often the reader is left without a sense of actually what is being described nor have a "hat to hang on to" when talking about relative differences with another product the reviewer might also be pointing to.

Similar to the AKG K371 back in April 2021 as a discussion of headphone measurements for circumaural (and supraaural) devices, today, I want to focus on one of the first IEM-type (In-Ear Monitor, also called "canalphone") transducers I bought back in the early 2000's. This is the classic noise-isolating Etymotic (often stylized as Etymōtic) ER-4B microPro Earphone. The very first ER-4 came out in 1991 and I believe the 4B version I have is reflective of the intent of that very first design.

While this specific ER-4B model has been discontinued for awhile now since early 2010s, there are still a number of ER-4 series products out there including the ER-4XR ("eXtended Response" meant for "music lovers" who want a bit more bass) and ER-4SR ("Studio Reference" for flatter frequency response). 

As suggested by the variants, Etymōtic makes these earphones for different target uses over the years. This '4B' model was meant for technically accurate "Binaural" monitoring purposes. Etymotic aimed for a flat response that follows a "diffuse field" target (great discussion here on the different targets BTW). 

As We Hear It: Quis custodiet ipsos custodes (by T. S. Gnu)

Quis custodiet ipsos custodes?

By T. S. Gnu

The value of articles in a magazine covering a given field lies in the new information (or well-presented summary of old information) that it conveys to the reader. The columnist watches the industry for new ideas and technologies, improvements to older technology, trends that may be worth keeping an eye on for better (e.g. the availability of ever better audio equipment at lower price points) or worse (e.g. the ever-increasing dynamic compression in recorded releases), and then cogently presents these to the reader. In light of recent positions that have been taken up both in columns and editorials, it behooves one to ask: Who Watches the Watchers?

The default stance that we see is often that these people have been in the business for a while and are, therefore, experts whose opinions must carry the weight of that expertise. In order for our stalwart writers in the audio press to be considered experts, they need to have carried out some research in the area that they are claiming expertise; mere experiential anecdotes do not fulfill this requirement. Even if one were to acknowledge their self-professed expertise/authority, there is a requirement — a duty even — to question the content of their statements before the statements can be taken seriously.

Using the MeLE Mini PC for Upsampling/Filtering - HQPlayer Desktop 4 streaming from Roon. [Going forward, AVX2 needed for HQPlayer + Roon... For some reason.]

Hey folks, a few weeks ago, I mentioned that I've got the little MeLE Quieter2Q Windows 10/11 computer in my sound room these days used as a low-power (<10W) Roon streamer capable of 2.0 and 5.1 multichannel. The computer is relatively powerful for just an audio device handling Roon streams; 8GB DDR4 RAM, a 2.0+GHz turbo Celeron J4125 quad-core CPU is certainly much more than needed just to basically get data from the gigabit ethernet and shove it to USB or HDMI for playback!

It works fantastically also as a little fanless HTPC for movies with 4K video and audio bitstreaming. A tip: K-Lite Codec Pack works very well, it can even play MKV/MKA files with lossless TrueHD-Atmos like the 2019 Beatles Abbey Road BluRay rip which I know will trip up some HDMI hardware.

I mentioned in the previous article that it might be fun to consider utilizing the processing power of the little fanless box for audio. For many Roon users, one way of taking advantage of processing power is by using HQPlayer from Signalyst for high-quality upsampling with digital filtering, and possibly even PCM-to-DSD conversion. 

DEMO: Listening to the Cayin RU6 R-2R noise and distortions with headphone load. Confirming subjective impressions. And Jim Austin / Stereophile's "Thoughts On Reviewing".

Notice that the quest for high fidelity has always been, almost exclusively, a male pursuit. A picture from the Edison Diamond Disc and the "tone tests" done back in the day circa ~1916.

I've been critical of many audiophile magazines, websites, and YouTube channels because it's hard to believe some of these individuals truly can hear what they report. I know, it's perhaps "rude" to question subjective claims, but unless one questions stuff like this, how are we to differentiate thoughtful critical listening from potentially biased claims of sound quality?

For example, I honestly doubt the folks who claim to hear big differences between cables. I think it's silly that some people insist they hear differences because of unsubstantiated "jitter" effects in digital audio. Those who think "bit-perfect" playback can sound very different have never over the years proved their case. Then there are those subjective reports that sing the praises of "hi-res audio" despite research never showing differences as being anything more than subtle. How about claims of the ability to hear the effect of "audiophile" ethernet switches, or USB noise/jitter devices?! As you can see in the links to these topics, I've tried to address them over the years so when questions come up, I can just point folks to areas covered already.

IMO, with time, more and more nonsense articles and claims have built-up in audiophile magazines and the Internet. I think young audiophiles must have difficulties making heads or tails about what is true anymore while negotiating this massive minefield of questionable information. I would not be surprised that some in this Industry actually prefer the presence of this "fog of subjectivity" because it allows people to make irresponsible claims about anything they want and not have to provide evidence so long as some key reviewers or readers have faith to repeat the belief over time! 

That the ongoing majority of audio hardware reviewing these days is purely subjective is a bit of a problem in the context of what I believe to be very poor reliability.

MUSINGS: Speaking "As If..." claims are truths, Attribution Theories, and the Numerical Madness of Chord (Mojo 2 and 104-bit DSP)? (And quick note on Multichannel "Kind Of Blue".)

As you've seen, recently, I measured the Chord Mojo DAC and we discussed the imminent release of the Mojo 2 which was formally unveiled on January 31 (2022). With that of course comes the flurry of media posts, reviews and advertising material hyping the new features which might or might not be useful depending on your needs.

An interesting interview (and I'm sure one of a number in the days ahead) is the one Darko conducted with designer Rob Watts released on February 1st. As much as I've been critical of Darko over the years (like this), I appreciate the interview, the questions, and perhaps showing some guarded skepticism; good stuff John for letting Watts speak.

The DAC infrastructure of the Mojo 2 is basically an "evolutionary" upgrade to the custom sigma-delta design of the Mojo 1 which is already very good. Watts admits to this evolutionary step (12:50). As suspected, they needed to keep Poly compatibility (2:15) - a shame because I think the retention of micro-USB is a real turn-off in 2022. These days, Bluetooth in a premium product I think is a basic mobile feature. At this kind of price point >US$700 for the Mojo 2, I think it's a little silly to also have to pay another >US$700, tolerate the added bulk, just to get wireless options but still limited to Bluetooth 4.1 A2DP/SBC last I looked; no aptX, LDAC, or even AAC codec support for higher fidelity (lossless Bluetooth would not be high on my priorities, but aptX Lossless is good I guess). As a general rule-of-thumb in consumer electronics, I think expensive add-ons like this usually don't make much sense, much less insist on ongoing compatibility across generations of products in the mobile space.