REVIEW: iFi GO Bar - Portable DAC / Headphone Amp (Cirrus Logic DAC, Balanced & Unbalanced).

My friend AudioPhil is really into his headphone gear. Recently he acquired the product above and asked if I might want to play with this for a few days... Sure, this looks interesting!

This is the new iFi GO bar (around US$320), a portable headphone DAC/amp. The USB interface is a USB-C form factor (480Mbps USB2.0 Hi-Speed), and there are outputs for single-ended/unbalanced 3.5mm TRS and balanced 4.4mm pentaconn. Interestingly, the company (iFi, subsidiary of AMR/Abbingdon Music Research) does not specify which DAC chip is used inside. Suspicion is that it's likely the Cirrus Logic CS43198 or CS43131, both are recent chips circa 2017 capable of "pseudo-differential" outputs and low-power consumption <40mW with rated THD+N of -115dB, DR 130dB, maximum PCM 32/384, and DSD256. The specs look good but don't get too excited about these ideal numbers when implemented in a USB dongle.

I don't know what's the point of being so secretive about the DAC chip used (Crutchfield says it's the 43131).

Pacific Audio Fest 2022 (PAF 2022) - Concluding observations and thoughts... (And a few videos!)

Well, the first PAF 2022 is now in the record books (see Day 1 and Day 2 for context). I honestly hope that the organizers, companies showing off their goods, and attendees all had a great time. I regret not getting the RMAF2019 T-shirt so made sure to grab one this time around and will wear it with pride among fellow audiophiles. ;-)

As I was driving home to Vancouver, BC, I was thinking about audio shows in general and also specifically about the PAF... What was seen, the experience of these shows as an audiophile, stuff like that.

Pacific Audio Fest 2022 (PAF 2022) - Day 2

The elevators heading up to the 13th & 14th floors of the PAF, and a view from elevator. Glorious hot 25-30°C weekend. IMO, we who live in the N.W. / Western Canada should never complain of the few days we get every year of the heat! So long as we don't hit closer to 40°C like last year's "heat dome"...

In total, I spent 2 days at Pacific Audio Fest 2022. The pictures and comments here will cover some of what I saw and general impressions for those rooms. See the Day 1 post as well.

Let's get going!

Pacific Audio Fest 2022 (PAF 2022) - Day 1

Hey there everyone, it's Pacific Audio Fest 2022 time here in Seattle! Since it was just a 3-hour drive from home in Vancouver, I figure it would be fun to check out the inaugural PAF this year. The last time I was at an audio show was back in 2019 for what would become the last Rocky Mountain Audio Fest - who knew!

My understanding is that PAF under the direction of Lou Hinkley brings with it experience from Capital Audio Fest held in Washington DC (which will be held this year November 11-13).

I think the audio geeks here in the Pacific Northwest and Western Canada appreciates the availability of an easily-accessible show in this part of the world to check out and listen to some of the latest (and greatest) the industry has on offer.

Summer Musings: On Stereophile's "Quackery, Gullibility, and Open-mindedness". Nature of audio devices. Truths in audio (and medicine).

Well ladies and gents, I guess it's official. Stereophile, at least in part, is not a journalistic venture based on a recent "My Back Pages" article. In the opening 3 paragraphs of "Quackery, Gullibility, and Open-mindedness", Rogier van Bakel basically discards the importance of skepticism as a journalist, and seems to set the stage for audiophiles to accept basically all manners of quackery and snake oil.

For those who have been on this blog over the years, you probably know that I'm a physician working here in Vancouver, Canada. I write these audio musings and technical review articles as part of my audio hobby/journey to go beyond enjoying the music as a consumer, towards further understanding of how the technologies work, with the hope that the results of the explorations may be helpful for other pilgrims along this path as we discuss hardware and improving sonic fidelity.

On quiet evenings when the kids are asleep and my wife is enjoying her TV dramas, examination of electrical devices and their waveforms can provide a much-needed distraction from the marvelous yet frequently incomprehensible complexity of human physical and mental states.

REVIEW: MeLE Quieter3Q (Celeron N5105, 8GB DDR4, 256GB eMMC) MiniPC: Fanless, 4K/HDR streaming. Getting closer! (Thoughts on Apple's M1 Mini as HTPC.)

Yeah, that's an old XBOX 360 Kinect camera back there! Hey, there are cool things you can do with this as a 3D scanner...

Greetings ladies and gents. In the posts for both the MeLE Quieter2Q post as well as just last week with the Beelink SER4 Ryzen 7 4700U computer review (BTW, I added an addendum - HDR10 works on that machine), I noticed questions, comments, and E-mails about utilization of these MiniPCs in the home theater setting; specifically video and HDR features.

Recently, I saw the availability of the MeLE Quieter3Q fanless MiniPC (currently around US$250). With the various feature upgrades, I figure that this is one which might qualify as a reasonable HTPC computer given that it features HDR video capabilities and a bit more CPU processing power. As such, I decided to take it for a spin. I bought the slightly more expensive 256GB eMMC storage model; since I am targeting video playback, it might be nice to have some extra storage for local data.

Much of what I said about the Quieter2Q applies here, so let's focus on performance differences and discuss this machine as a video streamer beyond audio purposes...

REVIEW: Beelink SER4 Ryzen 7 4700U (8C/8T) MiniPC - A small, quiet, fast, general "workhorse" PC... [Addendum: HDR works.]

These days, if we look around most homes, I think we'll see all kinds of computers used for different purposes in the rooms. I've talked about my main Workstation, the Server machine, even my Gaming rig a number of years back (much of that upgraded since). And a few months ago, we talked about the very low power fanless Celeron MeLE Quieter2Q which functions as a very stable stereo/multichannel streamer for Roon.

[BTW, there is an upgraded MeLE Quieter3Q now which is faster by ~30-40% featuring the Celeron N5105 processor for a few more dollars, but still no AVX2 if you're thinking about Windows HQPlayer as discussed here.]

Recently, I've been wanting to upgrade my 2016 Intel NUC 6i5SYH which in the last few years has been the heart of the audio measurements rig. Over time, as my measurement regimen has become more detailed, often using larger FFTs parameters, once awhile, I've started noticing that the old i5 CPU isn't keeping up with the processing needs and this shows up as glitches in the data such as when running multichannel REW "stepped sine" captures. Obviously, this will not do. ;-)

To remedy the situation, I got one of these Beelink SER4 Ryzen 7 4700U-based MiniPCs (8-core, 8-threads, currently less than US$450 for the 16GB RAM/512GB M.2 SSD model). There is also a more expensive SER4 with faster 4800U processor (8-core, 16-threads) if you need that extra speed.

This machine was purchased from standard retail channels; this review was not sponsored in any way.

Hi-Res THD(+N) vs. Output Level Measurements (ESS "HyperStream" vs. AKM vs. TI/Burr-Brown). And a bonus R-2R!

Notice last time as I ended off the post, I showed what I think is an interesting "high resolution" graph of THD(+N) vs. Output Level for the Topping D10 Balanced which uses the ESS ES9038Q2M chip. This was spurred on after some discussions on glitches and anomalies one might see due to the "HyperStream" architecture of the ESS chip.

These days, other than the occasional fully multibit or discrete R-2R DACs, the vast majority of what we're using are multibit/multilevel sigma-delta devices. This includes the brands I have listed in the upper graphic; Asahi Kasei Microdevices (AKM), ESS Technology, and Burr-Brown (which was acquired by Texas Instruments in 2000). We'll also talk about the Philips later. ;-)

Today, let's have a look at "high res" THD(+N) vs. Output graphs (XLR output where possible to keep noise as low as possible) comparing different DACs from these companies...

REVIEW: S.M.S.L. DO100 DAC [Part III - DSD, Subjective, AMPT Recording, and Conclusions]. And a very close look at the Topping D10 Balanced THD(+N) vs. Level graph.

As you can see, the SMSL DO100 displays DSD samplerate in the form of DSD64 (64 x 44.1kHz = 2.8MHz), DSD128 (5.6MHz), DSD256 (11.3MHz) and DSD512 (22.6MHz).

Okay audiophile friends, let's finish off the trilogy of posts on the S.M.S.L. DO100 DAC with some final measurements around DSD performance, let's talk about subjective listening impressions, and as usual, let me provide a direct recording from the XLR output for comparison with others I have done (as discussed here).

We'll then put this all together as final concluding thoughts on this device.

Notes on DAC DSD (1-bit PDM) measurements going forward...

In the early 2000's, we witnessed the battle over hi-res audio in the form of SACD vs. DVD-A. SACD, the brainchild of Sony, utilized a 1-bit Pulse Density Modulation (PDM) method they called DSD (an advertising term) whereas DVD-A had the ability to store up to 24-bit, 192kHz Pulse Code Modulated (PCM) digital audio data (multichannel up to 24/96).

From the beginning, there were concerns about this push towards 1-bit systems into the consumer space along with claims that 1-bit PDM should form some kind of archival foundation for music. There were critics include Lipshitz and Vanderkooy - see their paper "Why Professional 1-Bit Sigma-Delta Conversion is a Bad Idea" from the September 2000 AES. And the next year in May 2001, they followed up with "Why 1-Bit Sigma-Delta Conversion is Unsuitable for High-Quality Applications". Even Bob Stuart chimed in on the unsuitability of DSD for "high-resolution audio" back in 2004. This is no surprise since Meridian was firmly with DVD-A including developing the MLP compression system which subsequently has been licensed by Dolby and renamed TrueHD; it looks like Dolby and Meridian had an arrangement dating back even to 1998.

These concerns around fidelity and the unsuitability of 1-bit PDM as an editable format in audio production are why in the professional world, we see audio recorded and edited in 24/352.8 "DXD" and Sony's own "DSD-Wide" (8-bit/2.8MHz) instead of DSD64/1-bit "DSD-Narrow".

While this was playing out in the academic/professional arena, the advertising industry including the "mainstream audiophile media" championed DSD and published all kinds of flowery words suggesting how it sounded "more natural", or "analogue-like" compared to PCM. While I don't think we can put an exact date on when DVD-Audio officially died as a viable commercial product, I think by 2005 it was quite clear that hi-res physical formats were not going to be mainstream and DVD-A did not have the number of titles available compared to SACD. My sense is that the hybrid-SACD feature with both DSD and CD-compatible layers was a major differentiating factor that has resulted in still a trickle of SACDs released these days.

I'm bring this stuff up now as an extension to the discussions around SoX-DSD and the Philips Test SACD articles last year during my series on the Topping D90SE review because I've been thinking about how best to standardize the DSD test signals I use when testing. Different DACs tend to handle DSD playback differently and I wanted to make sure that my test signal parameters are at least somewhat in line with the music encoded on an SACD or maybe DSD128 download these days.

REVIEW: S.M.S.L. DO100 DAC [Part II - PCM Resolution]. (And on MQA's distasteful environmental claims...)

As we continue to evaluate the S.M.S.L. DO100 DAC, let's spend time today delving into the resolution that this machine provides as a PCM DAC (see Part I last week for filters and jitter performance). Given that PCM is the de facto digital modulation scheme, this post will form the heart of DAC performance evaluations. We'll leave DSD to Part III along with discussions of subjective performance.

With PCM data, this DAC will accept up to 32/768. Let's run some tests as per usual to see how this device compares to others I've looked at on this blog. For most of the tests, I will use my Raspberry Pi 4 "Touch" (USB) or a Logitech Squeezebox Touch (S/PDIF) as digital source. The E1DA Cosmos ADC will be used with or without the Cosmos APU to measure. For some of the REW-based tests, I will perform a simple loopback that looks like this:

Intel NUC → SMSL DO100 DAC → [Cosmos APU] → Cosmos ADC → Intel NUC

As usual, all cables are generic RCA when testing unbalanced, for XLR measurements 6' Monoprice Stage Rights were used.

Unless otherwise noted, the DO100 will be set-up to use "FL6" Linear Steep filter.

Without further ado, let's jump to it...

REVIEW: S.M.S.L. DO100 DAC (dual ESS ES9038Q2M) [Part I - Overview, Filters & Jitter]. (And the likely continued contraction of MQA...)

Over the last number of years, we have seen a proliferation of DACs from Chinese manufacturers offering models of increasingly better resolution - higher fidelity - and greater feature set. These days, I am of the opinion that we have achieved way above and beyond the ability for human hearing to differentiate these machines unless the manufacturers purposely added some kind of "coloration" to the analogue output whether it be frequency response or changes to the noise and distortion levels (the "tube sound" being a prototypical example we may come across).

As you can see in the image above, we have the S.M.S.L. DO100 DAC (~US$250) in today for review. I bought this unit through retail channels and intend to either use it myself or give it away if I have no need for it.

For many devices these days, opening the manual will show us technical information like the frequency response of the filters in this example. I think this is a nice evolution among manufacturers recognizing that showing product performance is important to educated customers with graphs and technical details rather than mere prose which often provides little satisfaction for the consumer's intellect.

Today, let's start a multi-part look at this DAC; no need to hurry because I think the performance at this price point warrants serious consideration and the many ways and features one can gather performance metrics on (I don't promise to test everything of course!). Obviously it's not an expensive device, has a remote controller, has both unbalanced RCA and balanced XLR outputs, Bluetooth 5.0 input, capable of up to 32/768 PCM and DSD512 (1-bit, 22.6MHz) using USB 2.0, along with S/PDIF TosLink and Coaxial inputs for up to 24/192 and DoP DSD64. No money wasted on MQA licensing. Depending on what we find, this might be right for you...

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. (And REW IMD vs. Level Step!)

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.

MeLE Quieter2Q (8GB DDR4, 128GB eMMC, Celeron J4125) Mini PC: An inexpensive, silent, multichannel Roon Endpoint. On Paul McGowan (PS Audio): "digital audio is soooo noisy", and "computers are the worst". [+ Windows 11 Update]

MeLE Quieter2Q (~US$250) box and contents. Notice VESA mounting plate (top left) included which is handy I think if used as a monitor back-mounted computer.

Over the last number of years, I've been a Roon user (lifetime membership, no I have not been subsidized in any way by the company). Although not perfect, it works well for me and I've certainly enjoyed the bountiful metadata this interface provides. The Roon software has unified control and access to my music library through Roon Core running on my Windows Server machine. In doing so, this has brought all the hardware playback systems in my home under the same "umbrella" whether it's my Workstation PC (listening to music writing these blog posts), on my phone using Bluetooth headphones while doing housework, or casually streaming Internet radio to the Chromecast Audio - Roon serves them all. The main item on my wish-list is for Roon to support streaming from the library remotely such as from the office.

For those who have read this blog over the years, you'll know that I like multichannel audio playback (discussed here, and here among elsewhere). No, I am definitely not one who thinks 2-channel is somehow "audiophile" territory and that multichannel is the domain of the "home theater guys". Audiophiles IMO should be greedy; we want it all because the love of music and the experience of great sound quality do not end the moment we go beyond 2.0 or 2.1 channel layouts! Some of the best sonic experiences I have had are with multichannel content and hardware.

As you likely know, I've been an advocate for Raspberry Pi devices, like the Pi 3B+ "Touch" and Pi 4 "Touch" builds discussed over the years. I still use these when I run my DAC tests given the convenience of the touchscreen and of course the price represents great value. However, there is a feature which still eludes the Raspberry Pi boards - I want easy multichannel Roon streaming in my main soundroom.

REVIEW & MEASUREMENTS: Chord Mojo DAC/Headphone Amp. A note on LH Labs (Light Harmonic "subsidiary") audio crowdfunding. And Neil Young's ultimatum to Spotify. [Early Mojo 2 specs.]

Mojo as shown here in the official rubber and leather Mojo Case. Looks and feels great in the hand. Shown with AKG K371 headphone.

Well, in the "better late than never" category, when I returned my friend AudioPhil's Cayin RU6 the other week, I borrow his Chord Mojo ("Mobile Joy", ~US$475 new but I think currently discontinued) for a spin!

This DAC has been out since October 2015! That's ages ago in the world of electronics. However, to be honest, high fidelity audio reproduction is rather ageless whether the device is 10 months old or 10 years old. So long as the internal components aren't deteriorating with age ("break-down" instead of "break-in", right?).

As you've probably seen in countless reviews on the Mojo (like here, here, here), this seems to be quite a popular DAC with a good following. It has been said that Chord sold something like 100,000 of these over the years. Objectively, the Stereophile review in fact showing some impressive performance results back in 2016.

As usual, Chord gear tends toward the large bulbous glowing buttons, at times steampunk metal esthetic. Colors are used to provide feedback on volume (the pair of buttons for +/- volume) and the main power button (red in image above) which changes color for sampling rate. I think this is an acquired taste and figuring out the colors will take some time as you get used to the sequence of colors in a rainbow with red (lowest volume/samplerate) on one end and purplish/grey/white (highest) on the other..

REVIEW & MEASUREMENTS: Cayin RU6 R-2R USB Dongle DAC/Headphone Amp. Considering "Intentional Imperfections". (Topping D90SE -60dBFS input graphs.)

In the last few years, we've seen a resurgence in interest around R-2R DACs. Back in the day (like these old CD players for example), multibit ladder technology was the way to do the conversion until the rise of 1-bit and multilevel sigma delta modulation DACs became the norm.

High quality R-2R does require extra effort to make sure the resistor levels are precisely trimmed to achieve higher resolution. This is why hybrid techniques have also been implemented over the years such as the TI/Burr-Brown segmented architectures (like with my TEAC UD-501).

With this post, let's focus on the Cayin RU6 DAC (~US$250), a new USB-C dongle device (comes also with a USB-A adaptor) which aims to provide high performance headphone playback of PCM up to 24/384 and will accept DSD256 by converting the 1-bit SDM to PCM internally (no native DSD conversion).

Thanks to my buddy AudioPhil for lending this device for testing!

Using Victor's Oscillator as reference (1kHz, ultra-low distortion analogue sine generator). A quick peek at the APx555B Analogue & DAC Signal Generators @1kHz. And on playing music "for fun"!

Note the 2-pin power connector on the lower left.

As you've seen on the blog over the last year, I've been using the E1DA Cosmos ADC from Ivan Khlyupin for a number of measurements recently (early report discussed here). I remain quite impressed by the performance of this little device with some caveats (lower input impedance, individual unit idiosyncrasies including what "grade" device one has).

While the ADC comes pre-calibrated by E1DA and unless you really want to spend some time playing with it, one should probably just leave it alone. Nonetheless, it's pretty clear that this is the kind of device made by and for audio hardware geeks! ;-) One has the opportunity to use the Cosmos_Tweak Windows program to fine-tune the calibration by changing independent ADC 2nd and 3rd harmonic compensation amounts, SDM integrator setting, and digital filter for the ESS Tech ES9822 chip.

So then, for this post, let's spend some time in the area of calibration and see if we can tweak the ADC using the device above - Victor's Oscillator (US$57) - an ultra-low distortion, 1kHz analogue signal generator which comes pre-assembled and tested from Riga, Latvia. As you can see in the image, there are 2 single-ended RCA outputs, with volume control ranging from 300mVrms (-8.25dBu) to 2.7Vrms (+11.0dBu). Note that a 10kHz version (and other custom versions) can be purchased as well but for typical audio purposes, 1kHz is in line with human hearing sensitivity.

As We Hear It 2022: Hypex nCore NC252MP DIY, The Joys of Modern Digital Audio, Upsampled Streaming, and Audible Amplifier Differences.

Happy 2022 everyone and greetings from Honolulu. As Bing Crosby once sang, "Here we know that Christmas (and New Years) will be green and bright" in Hawaii. A welcome first escape from Canada since the Pandemic began for myself and the family. Always good to escape winter in Canada for a little bit even if it's from relatively mild Vancouver although this year looks like we also avoided the snowy cold snap!

As a first post for 2022, let's look in the (virtual) mailbag a select a few items from readers for an "As We Hear It" post that have come in over the last number of months.