Moon by Simaudio Evolution 780D D/A processor Measurements

Sidebar 3: Measurements

I measured the Simaudio Moon Evolution 780D with my Audio Precision SYS2722 system (see the January 2008 "As We See It"). Source materials were WAV and AIFF test-tone files, played with Pure Music 3.0 on my MacBook Pro running on battery power. Apple's USB Prober utility identified the processor as the "MOON USB DSD HD AUDIO" from "SIMAUDIO LTD," and confirmed that the 780D's USB input operated in the optimal isochronous asynchronous mode. The AudioMIDI app indicated that the Simaudio DAC operated at all PCM sample rates from 32 to 384kHz, with a bit depth of up to 32 integer. The 780D operated successfully with both DSD64 and DSD128 data fed it via USB.

The maximum level from both the balanced and unbalanced outputs was 2.07V, with correct absolute polarity. Though a little higher than the specified 100 ohms, the output impedance at all audio frequencies was still low, at 246 ohms balanced and 149 ohms unbalanced. The impulse response with data sampled at 44.1kHz (fig.1) was typical of a finite impulse-response (FIR) reconstruction filter, with the symmetrical ringing to the sides of the single sample at 0dBFS mapping the filter's coefficients. This filter gives a very fast rolloff with 44.1kHz data (fig.2, red and magenta traces), with complete suppression of the aliased image at 25kHz of a full-scale tone at 19.1kHz (cyan, blue traces, footnote 1). Also evident in this graph is that the 780D's harmonic distortion is very low, with the second harmonic lying at –100dB (0.001%).

Fig.1 Simaudio Moon Evolution 780D, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).

Fig.2 Simaudio Moon Evolution 780D, wideband spectrum of white noise at –4dBFS (left channel red, right magenta) and 19.1kHz tone at 0dBFS (left blue, right cyan), with data sampled at 44.1kHz (20dB/vertical div.).

Fig.3 is a more conventional way of showing frequency response, plotted with data sampled at 44.1, 96, 192, and 384kHz. The ultrasonic rolloff follows the same shape, but with a sharp cutoff just before half the sampling frequency with the three lower rates. Note also the superb channel matching in this graph: the left and right traces precisely overlay each other. Channel separation was also superb, at >120dB in both directions below 3kHz, and the Moon Evolution's noise floor was both very low in level and free from any power supply-related spuriae (fig.4).

Fig.3 Simaudio Moon Evolution 780D, frequency response at –12dBFS into 100k ohms with data sampled at: 44.1kHz (left channel green, right blue), 96kHz (left cyan, right magenta), 192kHz (left blue, right gray), 384kHz (left blue, right red) (1dB/vertical div.).

Fig.4 Simaudio Moon Evolution 780D, spectrum of 1kHz sinewave into 100k ohms, DC–1kHz, at 0dBFS (left channel blue, right red) and –60dBFS (left green, right, gray); linear frequency scale).

When I fed the 780D dithered AES/EBU data representing a 1kHz tone at –90dBFS with first 16-bit data (fig.5, cyan and magenta traces) and then 24-bit data (blue, red), the increase in bit depth dropped its noise floor by almost 24dB, suggesting resolution of close to 20 bits. This is state-of-the-art DAC performance. No harmonic-distortion components can be seen, but the 24-bit data unmask what appears to be a spurious tone at close to 5.1kHz. However, this is very low in level. With its high resolution and overall low level of noise, the Moon 780D's reproduction of undithered 16-bit data describing a sinewave at precisely –90.31dBFS was exemplary (fig.6), with zero DC offset in the left channel (blue), and just 25µV positive offset in the right (red). The three DC voltage levels described by the data are well differentiated. With undithered 24-bit data, the Moon output a well-formed sinewave despite the very low signal level (fig.7).

Fig.5 Simaudio Moon Evolution 780D, 44.1kHz data, spectrum with noise and spuriae of dithered 1kHz tone at –90dBFS with: 16-bit data (left channel green, right gray), 24-bit data (left blue, right red) (20dB/vertical div.).

Fig.6 Simaudio Moon Evolution 780D, waveform of undithered 1kHz sinewave at –90.31dBFS, 16-bit data (left channel blue, right red).

Fig.7 Simaudio Moon Evolution 780D, waveform of undithered 1kHz sinewave at –90.31dBFS, 24-bit data (left channel blue, right red).

Fig.8 confirms the very low level of harmonic distortion, even into the demanding load of 600 ohms. With a full-scale tone, the second harmonic lies at –106dB (0.0005%), the third at –110dB (0.0003%), and no supply-related spuriae are evident. Intermodulation distortion is also extremely low, though the spurious tone at 5.1kHz again can be seen, along with another at 10.2kHz (fig.9).

Fig.8 Simaudio Moon Evolution 780D, spectrum of 50Hz sinewave, DC–1kHz, at 0dBFS into 600 ohms (left channel blue, right red; linear frequency scale)

Fig.9 Simaudio Moon Evolution 780D, HF intermodulation spectrum, DC–30kHz, 19+20kHz at 0dBFS into 100k ohms, 44.1kHz data (left channel blue, right red; linear frequency scale).

Tested for its rejection of word-clock jitter—S/PDIF data fed via 15' of generic TosLink cable—the Simaudio 780D performed superbly well with 16-bit J-Test data (fig.10), with no sidebands visible, and with the odd-order harmonics of the low-frequency, LSB-level squarewave extremely close to the correct levels (green line). With 24-bit J-Test data, whether via TosLink, USB, or AES/EBU (fig.11), the noise floor was very clean, though the low-level tone at 10.2kHz was still present.

Fig.10 Simaudio Moon Evolution 780D, high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 16-bit TosLink data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

Fig.11 Simaudio Moon Evolution 780D, high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 24-bit AES/EBU data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

I can't quibble: Simaudio's Moon Evolution 780D offers superb measured performance.— John Atkinson

Footnote 1: My thanks to Jürgen Reis, of MBL, for suggesting this test to me.
Simaudio Ltd.
2002 Ridge Road
Champlain, NY 12919
(450) 449-2212

georgehifi's picture

By Michael Fremer
"However, not even the finest DAC can make me appreciate the sound of 16-bit/44.1kHz CDs. Through the 780D they sounded about as good as they can"

Sorry Michael, but I've heard this blanket statement made all too many times now, and I very much believe that to get the best from CD PCM, it should NOT be converted/compared (played back) through a DSD/Delta Sigma dac.
It should only be converted (played back) through a true well sorted Multibit dac from today designers to get the best sound from it.
And therefore the two cannot be directly compared, because you need two different dacs with differing topologies to do it with.

Cheers George.

rompolompo's picture

Why review a digital product by a person who hates digital technologies?

Jerry Garcia's picture

Michael Fremer 2 days ago
Johnny, Johnny Johnny//Ha ha ha …. fine.

Enjoy your digits.

All of you!

Enjoy you SEEEDEEES. Although you know, most people don’t listen to them. Research shows that they mostly use them for target practice (blah blah blah).

CDs are going away. Vinyl grows. You don’t understand why, so you feel the need to explain it using this one record? Really?

Quoting ignorant sources who don’t really know how best to explain vinyl’s allure and who are left to say “rich and warm” is really pathetic.

Vinyl shouldn’t sound “warm” and it doesn’t unless you use a warm sounding cartridge and/or a warm sounding phono preamplifier. Bright recordings should sound so on vinyl and do (etc.).

You are welcome to listen to any of my YouTube vinyl rips that make CDs sound awful as they have always sounded. Yes my analog front end is costly but you are writing about “vinyl” in the aggregate so I urge you to check out my videos, with 96/24 rips via a Lynx HiLo. Yes YouTube dumbs them down but the essence still comes through as the comments demonstrate.

ALL FORMATS PRODUCE COLORATIONS! Digital’s colorations are more profound as they occur mostly in the time domain.

CD sound sucks and always has. Worse than the sound is how it makes people “feel”. I realize that doesn’t compute for measurement freaks, but the brain knows what’s wrong with digital, especially with CDs and lower resolution formats that completely mess up the timing).

Phase shifting filters produce panic in the brain, which is why people don’t really sit down and LISTEN to digital for very long before finding something else to do…whereas with vinyl playback, people find they can sit and listen and listen, which they do.

That better explains the resurgence than any of your picayune observations…You miss what’s going on.

That’s fine! Enjoy your digits and those of us who prefer vinyl will enjoy our records.

We don’t care what you write or think about this.

We are winning.

And we don’t care about the hysterical negative comments sure to follow this. Trust me: we don’t care….and you’d be surprised who’s on this vinyl bandwagon….people with tech knowledge equal to or surpassing yours John…

John H. Darko 2 days ago
Mikey – nice to hear from you.

If you don’t care what I write, why respond? And why make it personal (with insults)?

What is “my” technology exactly? I don’t profess being wedded to any particular tech. My message is one of pragmatism, not idealism. Anything else would make me look like a zealot.

You KNOW I love vinyl. We’ve even spoken about it over dinner, have we not? Remember my enthusiasm for Japanese Bowie pressings in Las Vegas? That’s a photo of my record collection as it currently stands at the top of the article. One of those records – actually TWO – were used here for illustrative purposes only.

Of course I have played far more records on the RP1 than those specified in the piece. Alas, every single one fails to cut it with layer separation and resolution when compared to the equivalent digital file. That’s the way I hear it.

However, I am not saying (or even implying) that digital is the be all and end all. Merely showing here how the mainstream press endlessly promotes vinyl with a positive spin (and zero analysis of its shortcomings) and in doing so lays a bear trap for the vinyl newcomer expecting some form of audio nirvana from an *ENTRY-LEVEL* table.

“We are winning.” Say what now? I just don’t see this battle/war (to which you allude). What I do see is the potential for disappointment with this entry-level table if purchased on the back of exposure to endless positive press about the vinyl revival.

And as mentioned in the closing remarks, I acknowledge that spending more on a ‘table brings a LOT more performance to the (err) table. No doubt you use better gear for your needle-drops than an RP1? Care to tell us what vinyl newcomers should be spending their cash on?

PS “ALL FORMATS PRODUCE COLORATIONS! Digital’s colorations are more profound as they occur mostly in the time domain.” <--- and yes, I agree with you on this but the RP1's shortcoming are more pronounced to my ears than can be counterbalanced by superior time domain performance.

georgehifi's picture

Is that right?? Michael Fremer is anti digital.???

yuckysamson's picture

I don't think Mr. Fremer "hates" digital. He's saying he prefers the performance, in every regard, of either hi rez or vinyl to redbook. Before getting on a high-horse about this notion, it might be worthwhile to consider the idea that this isn't akin to saying "I like automatic instead of stick" or vice versa or two things that are "different" experiences. THis is like saying "Oddly I don't like playing with the files from my 2002 Nikon D1 when I can now use an 810". It's long been recognized that the 44.1 Format is a heavily impaired one which, for obvious reasons the industry couldn't upgrade on year after year (like has done with digital photography) and even further what's come to light is that there were significant errors made in the way these limited resolution files were created.

Insulting the guy for saying something legitimate is silly.

Jerry Garcia's picture

Michael Fremer about 8 hours ago
Ha! I’m winning this war because vinyl sales, turntable sales, and accessory sales continue their growth so I’m not “upset”. I’m not “arrogant” either.

I just don’t like being attacked. Do you?

If so here you go:

You are correct: digital is more “consistent”: consistently bad and not very pleasant to listen to.
And frozen processed food is also more “consistent”. Always the same, you can count on it! And always bad.

Calling what I do a racket? “Snake oil”. You’ve gone off the rails.

So go f…k yourself. Don’t like that, then don’t come here and INSULT me and call what I’ve spent 30 years building a “racket”. Now it’s your turn to call me “unprofessional” for not sitting back and letting you insult me. I’ve dealt many times with assholes like you.

John H. Darko about 8 hours ago
…..aaaaaaaaaaaaand with expletives thrown and personal insults being traded we reach the end of this discussion as it stands – this post’s comments section is now CLOSED.

georgehifi's picture

I didn't say he's anti digital, just queried it from another poster?

What I am questioning though is Michael Fremmer's statement, that you can get "the best from 16/44 PCM" by using a DSD delta sigma dac.
You can't, to get the best from PCM it is has to be converted using multibit conversion to get it "bit perfect" from it.
From what I've read/learnt about it.
As a dsd (delta sigma) dac has to convert pcm back into dsd in real time before it can play it back in dsd, an it's a facsimilie of it. A multibit dac does not, it converts in real time.

Cheers George

rzr's picture

Stereophile has no expertise in the area of digital music in regards to music servers, streamers, etc.. or the know how on how to make them work or provide maximum performance. This review is a prime example of this.
Where do I start?
#1: Fremer would rather listen to vinyl than digital, that's no secret. But he doesn't realize that when he compares digital to vinyl, he is comparing a $200k vinyl setup to a much cheaper digital setup, not realistic. He needs to come down to earth in his reviews and statements about the differences between the 2 using a vinyl setup that costs the same as a digital setup. He can't do this!!
#2: Fremer balks about purchasing a $250 NAS drive for this review. Fremer's 2 bolts that hold his cartridge onto the tonearm probably cost more than that! The reason I bring this up is that some manufacturers claim that their products sound better when using a NAS, in this case with the Moon, we will never know since it wasn't tested.
3: Fremer bitches about no documentation that can help him setup the Moon in different configurations. Again, this goes back to my #1 point above: Stereophile needs to get expertise in this area. I purchased an Auralic Aries and the pamphlet they send out is a couple of pages. But if you know this stuff, it was very easy for me to use the Lightning software, or the Lumin software (both on iPad), plus having the data stored on a NAS or using Minimserver on my OSX server, or a direct connected disk. Very easy to do! What are all the possibilities with the Moon 780D? The reader will never know after reading this review.
#4: Fremer keeps touting his Soloos setup. Soloos was not that good when it was new years ago in SQ and compared to the latest playback software, its pretty bad. Today, Roon SQ isn't as good as some of the other players like Audirvana. Roon along with Soloos are noted for their GUI interface and metadata collections: not a big deal to me. SQ is much more important than GUI, but with the new software like Lightning DS and Lumin and others, you get both. Hopefully, Roon SQ will improve. It seems that all the new music servers can support Roon and other software.

Bottomline: Stereophile needs to get somebody with much more experience when reviewing current digital systems like a music server/streamer so they can put the product thru the paces to get maximum performance. I don't want to hear that a reviewer was limited in his testing because something wasn't documented, documentation should not be an excuse, the reviewer should have enough knowledge to dig in and come up with many ways to configure the system for best performance. For example: Auralic is not going to document that using the Lumin software might sound better than using Auralic's own Lightning software. Just like Fremer has enough knowledge to setup tonearms and cartridges in his sleep and would never use documentation as a scapegoat, Stereophile needs to have the same type of reviewer for the digital world.

Jerry Garcia's picture

The Perpetual Pilgrim

My nephew, Andres, has turned his audio hobby into a religion. He takes his quest for the 'Ultimate Sound' as seriously as the quest for eternal life. He is consumed by audio nervosa and spends his free time studying audio magazines and websites to find absolution for his past buying decisions, and blessings to make changes. Recently, he even sacrificed the value of a pilgrimage to Rome in favor of new interconnects -- based solely on a decree from his most trusted bishop, a 'Golden Eared' reviewer in one of the magazines.

He invited me to spend the weekend at his apartment to solicit confirmation for his pricey investment. When I got there, he raved about the 'night and day' difference using the vernacular of reviewers: romantic richness, sweet delicacy, fatigue-free tonal lusciousness, liquid voluptuousness ............ I'm beginning to suspect he needs a girlfriend.

I could neither confirm nor deny any audible improvement as I wasn't sufficiently familiar with the sound of his system, but I was skeptical of his claims. So I decided to conduct a test. Overnight, while on a bathroom break, I switched his anointed interconnects with my Radio Shack 'Gold' cables -- which can be purchased for the price of a Roman candle.

While sipping coffee the next morning, Andres opened his stereo cabinet and played his favorite SACD, The Mission soundtrack, from beginning to end. He turned up the chorale to concert hall volumes and praised the sound.

He had no idea he was listening to the profane 'Rat Shack' cables. It was clear that the 'night and day' differences he raved about was not apparent the day after the night. His belief that the new cables were in play was sufficient to justify his enthusiasm. This experience confirmed to me that people do not have reliable perceptual capabilities. Perception is cognitive and the brain tends to be the dominant factor – the brain tells them what they experience more than their senses.

The most publicized case in point concerns Trader Joe's house wine, 'Two Buck Chuck,' as Charles Shaw's Chardonnays are known. They got less respect than Rodney Dangerfield until the 2007 California State Fair's Commercial Wine Competition. There, 64 judges awarded it the prestigious Double Gold award. That placed it first not only over 350 other Chardonnays, but on top of the entire collection of 3,029 wines! Wine tasting competitions are always conducted blind. Would the judges have ranked "Two Buck Chuck" as highly had they been able to see the label? When faith in price, status or reputation is eliminated from the equation, judgments change.
How different might the annual 'Recommended Component Buyers’ Guide' be if audio components were evaluated like wines? Would 'night and day' differences be confirmed or non-existent in a double-blind testing protocol? It's one thing for a reviewer to claim a component is superior, it's quite another to prove it. When a reviewer recommends expensive upgrades without evidence of their primacy (and expensive equipment is virtually always deemed superior in the media), he is asking followers to part with their money on the basis of faith.

Nonetheless, Andres agonizes over the words in the 'Recommended Components List' like St. Augustine over the Scriptures. He has a divine belief that these products are accurately appraised by sound quality -- despite a complete lack of evidence to that effect. For the most part, products with good reviews sell, and those without, don't. That's a lot of power to put in the hands of a few pundits with questionable hearing, motives and methodologies. How many good products have gone by the wayside due to the prejudices and preconceptions of reviewers? Conversely, how much snake oil is still on the market for the same reason?

In a recent e-mail, Andres wrote, "I still don’t feel like I have my arms around my system, the big picture, yes, but the subtle things that ultimately define it, not yet.......hoping in the process to do that endless loop of keeping my ears tuned, attentive, and aligned with others."

I have no idea why he thinks his young ears have to be "aligned with others"? What is it that he wants to get his "arms around." Like sex, music is an emotional, not an intellectual activity. Constantly nit-picking the equipment ruins the experience.
Someone once said, "You can’t know what's best is unless you have heard everything." Andres will never have sufficient time nor energy to audition everything. Even if he could, he'll never know how his ultimate system would compare to the live event unless he'd attended it. And even if he had, his health, mood and the location of the seat he chose would affect his memory of the performance. That's taking for granted there was a live performance, and he's not listening to a synthetic creation of the recording engineer.

Even assuming his acoustic memory of the live event is impeccable, the recording flawless, and his 'dream system' provided perfect fidelity, his listening room acoustics will distort the sound enormously -- as any pair of studio headphones will demonstrate.
Andres needs to see the light and accept the fact that every facsimile of the live event is corrupted and deficient. If his system is capable of turning him onto the music, if it takes him to a blissful state, his prayers are answered. This endless search for the Holy Grail will only keep him a perpetual pilgrim.

B. Jan Montana

Jerry Garcia's picture

Michael Fremer about 9 hours ago
Better not attend a classical music concert! I had a subscription to Avery Fisher Hall and The New York Philharmonic and guess what? The folks who attend tend to be old so there’s lots of coughing and choking, an occasional stroke. If you concentrate on that, you can never enjoy the music but because what you hear from the stage is so compelling, that stuff is easily tuned out.

The alternative is staying home and listening to “perfect” sound with no live interruptions. Whatever are the minor and not very often pops and clicks, what’s also there, to my ears, is far more compelling. But each to his own of course.