MEASUREMENTS: USB Isolation with Nobsound ADuM4160 device and hi-res DAC. The world these days, and the audiophile microcosm.

 

After writing about very high resolution measurements with the E1DA Cosmos ADC last week and touching on basically "state of the art" fidelity like the Topping D90SE, for this week's post, I thought it would be good to talk about something more "fundamental". Often spoken of among audiophile tweakers but rarely have I seen evidence of actual value/effect for many of these devices.

Before I begin with this post or even show you anything, let me just say that I do not believe audiophiles need USB isolation for use with devices like DACs unless you know you have noise issues. I think we've all see indiscriminate suggestions that audiophiles need all kinds of noise filters and isolators (like this, or this). Sometimes these things cost quite a significant chunk of change compared to the downstream device (like DAC) itself!

Over the years, I have tried out a number of USB DACs with computers and simple streamer devices like the Raspberry Pi. With a normal set-up, I cannot say I have ever heard an issue with any of the various decent DACs I've tried. Likewise, measurements already suggest that in general there are no major noise issues with at least reasonable modern devices.

However, there are times when the system is complex enough where indeed you do see ground loops and noise like the 8kHz USB PHY noise pop through. A couple months back, I showed you some of this when we took the rather useless AudioQuest JitterBug FMJ for a spin in some of these situations! Today, let's look at the effect of that little inexpensive Nobsound ADuM4160 USB Isolator (typically can be purchased for <US$25) you see in the picture above.

EARLY LOOK: E1DA Cosmos ADC - affordable high performance measurements for the audio hobbyist!

As you can see in the picture above, I have one of Ivan Khlyupin's (aka IVX) Cosmos ADCs. It's not available yet on the market, so watch for when it's released from E1DA in the days ahead. Thank you Ivan for reaching out and sending this unit for me to use!

[If you're wondering about the E1DA name, as explained by Ivan, it comes from the pronunciation of "Ivan" as sounding like "E1" in Russian as opposed to the Americanized "Eye-Ven". "DA" as in "dah" ("да", "yes") - so it means "Ivan Yes".]

While this unit is one of his builds for external testers, I suspect that it should be much the same as the final product when available hopefully later this month. Obviously there could still be some changes with the final production release.

I think the price is slated for around US$150. Also, in the days ahead, E1DA will be releasing the "APU" (Analog Processing Unit) that can complement an ADC for measurements with the ability to notch out the 1kHz fundamental among other features allowing even more accurate measurements of very high performance gear. And there's also the Cosmos DAC coming as well to complete the "trinity".

For today, let's have a peek at the Cosmos ADC. Let's explore how to get it going, some of its features, and although still early days, we can take a quick look at measurements with this tool, with some DACs I have here.

Archimago's Musical Performance Track (AMPT): Standard test track for listener evaluation of source playback. [RME ADI-2 Pro FS R BE, Topping D10s, D10 Balanced, TEAC UD-501, Squeezebox Touch recordings.] Loss of RMAF, Bluetooth aptX Lossless. PS: Topping D90SE.

Over the years, we've seen websites, blogs, and videos try ways to demonstrate the sound of a hi-fi device or for the adventurous, even try to convey the sound quality of listening rooms. For example, there are binaural recordings at audio shows, soundroom demos, speaker comparison samples, etc. This is not an easy task because high-fidelity is about nuances and slight variations; not wholesale "obvious" differences for many devices like DACs or high performance amplifiers. Unlike what you might read in audio reviews, assuming you have a decent DAC already, a replacement would be unlikely to result in obvious changes in characteristics like bass response or claims that jitter effects are somehow obviously audible! Sorry folks, a lot of that kind of talk is just fantasy.

While it is convenient to view and listen to typical YouTube clips, I think we can all appreciate that sound quality would be highly affected by: the recording microphone, room acoustics, set-up quality, the lossy audio compression from YouTube among others that I may have missed. Dissociating the effect of the different components would be impossible. And obviously any time you use a transducer to convert the sound pressure into electrical signal (ie. speaker, microphone), there will be a significant reduction in resolution if we're trying to determine the effect of something like a DAC!

Then there's the issue of what music is being used? Is it music that audiophiles have general access to? Is it material that audiophiles/music lovers would even generally listen to? Obviously this bit is very subjective but I think there's something to be said about esoteric test material that might be recorded amazingly well, but just not adequately popular to have "mainstream" level acceptance. When "subjectivist" audiophiles complain that test tones are artificial and synthetic, is it that much different from listening to a handful of albums that barely anyone cares about? ;-)

SUMMER MUSINGS: On the dreaded "Digital Glare" in audio, and conversely, exaggerated analogue evangelism.

A reader E-mailed me the other day asking about what I thought of the dreaded "digital glare" because it was mentioned by a "more subjective reviewer" he was also connecting with.

Basically, I don't believe "glare" exists as a generalizable phenomenon that is somehow special to digital audio. Rather, my guess over the years on how some audiophiles started using this term is that many of the early CDs (not necessarily subsequent remasters) did sound overly bright and harsh. As much as I love the music on The Nightfly (Donald Fagen, 1982), Dire Straits' Brothers in Arms (1985), Dead or Alive's Youthquake (1985), OMD's Organization (1980, 1985 CD release), Culture Club's Kissing To Be Clever (1982, ?1984 CD), ABBA's The Visitors (1981, 1983 CD release), despite excellent dynamic range, the sound of these albums are just "bright", too "thin", a bit "glassy". Perhaps some of this also has to do with the synthetic instrumentation and studio techniques of the time.

SUMMER MUSINGS: Room EQ Preferences - Vintage Spendor SA1-like curve, Hang Loose Convolver (HLC), and the increasing relative importance of software.

Getting ready for an evening of digital filter evaluation!

I mentioned a few month back in my Spendor SA1 (1976) review/measurements that I really enjoyed the sound of these classic speakers!

While it would not be possible to exactly replicate their sound - these are complex devices with all kinds of unique properties including distortion idiosyncrasies and unique radiation patterns - to some extent, we can try to replicate the frequency response via DSP.

These days, we have the technology available to modify the sound we hear in the soundroom without great difficulty; the trick is to make sure the sound has improved, at least subjectively, when we add things like EQ or applied other signal processing.

Although some (typically more traditional) audiophiles will speak of maintaining "purity" of sound with minimalistic set-ups, if one is a contemporary technologically astute music lover and audiophile, especially one already using complex streamers, computer gear, networked libraries, I don't believe there should be any fear in going all the way using high-quality DSP to shape and adjust what we hear. In fact, from the frequency response perspective, we can "emulate" almost whatever we might want depending on the flexibility of the software used.

MEASUREMENTS / REVIEW: Topping D10 Balanced (D10B) DAC. Simple, no-nonsense USB DAC, excellent balanced sound quality.

Last month, I published on the Topping D10s DAC which performed excellently for such a small, USB-powered device. Fantastic price to boot!

Today, let's have a look at the newest sibling in this line of DACs released in July 2021 - the Topping D10 Balanced (I'll just call it D10B for short). As you can see in the image above, the contents in the box are similar to the Topping D10s, with manual (including measurements), pamphlet with various other Topping products listed, generic USB A-B cable, and for this model a couple of TSR-to-XLR male-male adaptors.

At <US$150, this is certainly still inexpensive. And as the name suggests, this baby is capable of balanced analogue output. Balanced transmission provides improved common-mode noise rejection and this should result in quieter analogue output including rejection of potential issues like mains hum in the signal.

I bought this DAC through the usual retail channels; no relationship with the company.

SUMMER MUSINGS: No... Not all amplifiers sound the same (but many do! ;-).

With both my Class D Hypex nCore NC252MP amp and linnrd's Class A Pass/First Watt SIT-2 in my sound room a couple months back, this allowed me to switch reasonably quickly between them to listen. You might be wondering about some comparison comments on how the amps sound. Certainly much has been said in the press about sonic differences between amps over the decades, but relatively little has been shown with measurements in an actual room using what comes out from the speaker.

First thing I'll say is, "No, not all amplifiers sound the same!". This should be obvious actually when looking at the objective measurements of the amplifiers and what they mean if we extrapolate the results to a known system.

Like I said, it seems uncommon to see measurements "in situ" with amps connected to the same DAC, preamp, and speakers to show differences. To demonstrate the differences in my room with my speakers, I set up the miniDSP UMIK-1 microphone in the room like so to run some sweeps and tonal FFT's for comparing:

Mega-taps upsampling: Remastero's Pan Galactic Gargle Blaster (PGGB) software. (Broadly on audiophile software & the noise boogeyman.)

This article came about after I received an E-mail from an audiophile friend who saw this Audiophile Style thread in praise of "math and magic". It links to a piece of software by a site called remastero, and the program itself is called "PGGB" (Pan Galactic Gargle Blaster), obviously referring to The Hitchhiker's Guide To The Galaxy with the main author named Zaphod Beeblebrox (who in the book is also the ex-president of the Galaxy). Cute, and of course the number "42" features prominently here and there.

In the past, we have talked about "audiophile" software that supposedly affect sound quality. Years ago, we talked about bit-perfect players (Windows, Mac) and really how "bit-perfect" is simply "bit-perfect" regardless of what software is used. We discussed questionable programs like JPLAY. Then there are the OS tweaks like Fidelizer. Neither JPLAY nor Fidelizer made any difference in my testing or listening.

That is not to say software doesn't make a difference at all. With the computing power we have these days, we can certainly perform highly precise filtering and DSD-PCM transcoding - like with HQPlayer. 

The idea with PGGB is that this is software that will take (in batch) various tracks you have and convert these to upsampled versions like 24/384 or 32/705.6 or even higher. In the process, applying very strong filtering (eg. on the order of >200M-taps sinc filter for some of the tests we'll run here, very impressive big number, right?). Furthermore, the website states that the software can apply settings for various levels of "transparency", apply HF noise filtering, uses noise shaping, adjusts gain monitoring for intersample overs, deal with convolution filters, and an apodizing setting. That's a bit of stuff so I won't promise that we'll hit on all these here. My intent is to at least have a good look at the foundation of the upsampling effect and the EQ function.

MEASUREMENTS: Topping D10s - an inexpensive high performance basic USB DAC with S/PDIF outs. And on "perceptibly perfect" DACs.

 

Hey everyone, I suspect many of you have already seen or heard of the Topping D10s by now (~US$100-110 at time of writing). It has been out since spring/summer 2020, a DAC released during the early pandemic.

Basically, this is an update of the Topping D10 which I reviewed back in 2019 with change to the DAC chip from the ESS ES9018K2M to the ES9038Q2M with improved specs - lower noise, higher dynamic range, etc.

I bought this through the usual retail channels as I'm planning to give the D10 away to a family member. Let's have a deeper look and consider the implications of this change in the DAC chip to the overall performance.

Apple TV 4K, 2nd Generation (2021, A12 Bionic SoC, 6th Gen Apple TV): A look and listen (to "Spatial Audio" on Apple Music)...

So guys and gals, let's jump from the lo-tech "audiophile boutique" passive AudioQuest JitterBug FMJ last week to talk about something hi-tech this time.

As I mentioned a few weeks back, I've been listening to some of the "Spatial Audio" music streaming off Apple Music these days. Easy to give it a shot with the 1-3 month trial period they're offering.

As I mentioned before, while I enjoy the content on headphones and can experience the difference Atmos streaming makes, as one who enjoys excellent high fidelity sound quality (ie. "audiophile"), the best, most natural way of listening to multichannel content is in the sound room where I have my multiple speakers set up. I have a modest surround system with the ELAC Debut 2.0 A4.2 Atmos speakers (previously measured) adding a bit of that height effect with Paradigm Signature S8 v.3 fronts, matching C3 center channel, full tower Studio 80 v.3 for rears and dual subs to make basically a 5.1.2 arrangement.

The trick with getting the multichannel content out to the room has to do with whether Apple Music allows the bitstream to pass through the playback device into the AV receiver that can handle Atmos. As I mentioned in that previous article, I can get the "bed" channels out (ie. 5.1, 4.0, etc...) using my wife's M1 MacBook Air running the recent macOS Big Sur release, but this is with the machine decoding the DD+ (E-AC3) + Atmos stream into 24/48 5.1 PCM sent to the receiver over HDMI.

For bitstream passthrough including the full Atmos encoding, at least at this point in time, the Apple TV works and let's talk about this box today for audio/home theater usage... As you can see above, I have the Apple TV 4K, Gen 2, 64GB here - this was released just recently April/May 2021 with the "A12 Bionic" 7nm SoC which actually was first used in the iPhone XS series back in late 2018. Certainly energy-efficient and plenty fast for non-multitasking media playback. If you don't need the storage, the 32GB model saves you US$20 - as usual, Apple has no SD card expansion for their devices. Internally, the machine has 3GB RAM.

MEASUREMENTS: Review of AudioQuest JitterBug FMJ. (And on Milind Kunchur's recent RCA vs. XLR paper.)

Hmmm... What does "LESS DIGITAL NOISE" actually mean? After all, noise that's bad enough to affect digital data will result in errors. Obviously, that would be very bad!

Normally, I don't review stuff like this because there's simply little reason to believe these kind of things do anything of value.

I know, this comes across as highly biased right at the start of a review post! But I want to be honest and I wasn't born yesterday so I know there are all kinds of claims in the audiophile world that simply do not pan out. Furthermore, I've had experience with the AudioQuest company (see the Dragonfly Cobalt / Red / V1.2 DAC review a few years back) and know that they have made claims which turn out to be untrue when tested.

Another admission going into this is that I was introduced to the AQ JitterBug back in 2015, and over the years I have seen other tests like the Audio Science Review thread from 2019. Having said this, I am happy to be swayed if I truly hear a difference or measurements show me that I should change my mind.

So, when a local audiophile friend bought the new AudioQuest Jitterbug FMJ ["Full Metal Jacket" - cute] (~US$60, released mid-May 2021) and suggested I borrow it for a week as he went on vacation, I figured it would be fair to give it a try and see if I can run some measurements to provide data to audiophiles at large on this update to the product. I promised him that I would give him my honest opinion.

MEASUREMENTS: 1MORE Triple Driver Over-Ear Headphones (H1707) with wired remote & microphone. And on Galen Gareis / Iconoclast Cables interview recently.

Alright folks, on the test bench this week is the 1MORE Triple Driver Over-Ear Headphones (let's just shorten name to 3DOE). If you've seen this headphone over the years (released around Christmas time 2018), you'll probably know that we need to clarify a couple of things.

First, they're not actually "over-ear" as in truly "circumaural" headphones. The earpads/cups are not big and unless you really have small pinnae, will sit "partially circumaural" with portions against the pinnae like supraaural designs.

Secondly, it's more of a "dual" driver design rather than "triple". There are 2 active drivers - a graphene-coated 36mm mylar dynamic driver, and a 10mm ceramic/piezoelectric driver for treble. The third "driver" is the passive "bass reflector", much like speaker passive radiators but inside a closed headphone reinforcing a certain amount of bass response.

The silver model like the one I have here is the graphene-coated version. There is also a gold-colored version out there which is a titanium driver without the graphene layer. I've seen comments that the sound is similar between the two versions. This one was bought through the regular Amazon retail channel (on sale for <US$150) and as far as I can tell, is the current model with an inline remote control plus microphone good for use with your smartphone.

SUMMER MUSINGS: Surround sound to the masses! In support of 3D Audio / Dolby Atmos in music streaming (Apple "Spatial Audio")...

Hey guys and gals, this week I thought I'd take a break from measurements and observe what's going on in the audio, audiophile, and streaming world these days. I noticed some discussions and even concern among music listeners around Atmos and Apple Music's drive towards "spatialized" streaming.

As audiophiles, let's think and talk about this for a bit.

First, let's do a quick background recap so we're all on the same page...

REVIEW / MEASUREMENTS: Pass Labs / First Watt SIT-2 stereo Class A amplifier. [And Stereophile steps in with MQA yet again...]

 

Greetings all. For this post, as you can see above, I've got something exotic to review / measure here at chez Archimago. It's a Pass Labs / First Watt SIT-2 stereo amplifier which was made in limited quantities back around 2011-2013.

This amplifier comes with a nice backstory; that of the silicon carbide (SiC) "Static Induction Transistor" which you can read about here (aka V-FET). The thought is that these transistors behave in a "triode-like" manner, hence perhaps they will be able to convey a "tube-like" sound. Furthermore, this device follows the general audiophile philosophy of "simplicity and minimalism" (quoted from the manual) as principles that would result in a device sounding "good". As such, this amplifier has only a single SIT gain stage, operates in Class A, built with minimal components, employs no feedback, and as expected, accepts single-ended input only.

Online I found this user manual and Japanese product flier for those wanting a bit more information from the company. The cost of this amplifier when it first came out was around US$5000.

REVIEW / MEASUREMENTS: (Mass)Drop + HiFiMan HE-4XX Planar Magnetic Headphones (with Brainwavz XL Round Hybrid earpads). Maintenance if the earcup detaches.

Well, as I've mentioned previously, I don't really need more headphones. ;-) Alas, I could not resist picking up these minty Drop + HIFIMAN HE-4XX Planar Magnetics locally used at a price I could not refuse! I also love how they look with the classic headband. The matte "midnight blue" color looks like a dark charcoal with a subtle powder bluish tinge.

I know there have been different opinions on the build quality of these headphones. Some of the early units had issues with right-left imbalance, driver failures, and broken hinges. According to this post, it looks like replacements with serial number 5XXX have many issues fixed. My unit here has serial number 57XX.

The hinge where it interfaces with the headband feels robust on this unit and I think the build quality is very good. The steel gimbal and metal sliders seem like they will be able to hold up to daily use. No complaints there. I did have an issue with the part interfacing the ear cup which I'll discuss below.

The stock cable is a little short for my taste at around 5'/1.5m (6' would be better for my desktop use). Notice that the cable is angled 90°, terminated with a 3.5mm connector which is fine for mobile use. I think a straight cable would have been preferred since most buyers would likely be using these open headphones at home almost exclusively. I like the soft, pliable nature of the cable although I have read some complaints that it can kink and fail. I don't think there's an issue, replacements are not expensive anyway.