Getting There... (Early HT Room Setup)

Back from my overseas business trip late last week. It's going to be really busy since I'll be moving to the new house in 1 week. Massive amounts to pack up!

Nonetheless, I didn't want the movers to be involved with the audio system so over the weekend I moved all the components and put together the stereo setup in the home theater room to just have a little "taste". Here she is... (Unfortunately the image is a bit grainy. Resorted to the old Nikon D70 as my D800 developed some autofocus issues and needed repairs.)

Hmmm. Looks like I need to straightening the power/cable/ethernet outlet at the back there...

Room size is decent: 20' x 15' x 8'. The TV is a 55" LG 55LW5600 mounted on a strong wall mount - I might go for a 70" in the future. Components:

- SONY SCD-CE775 SACD/CDP I bought back in 2001

- Emotiva XSP-1 pre-amp

- 2x Emotiva XPA-1L monoblocks connected to XSP-1 with Monoprice XLRs - 35W Class-A bias, max 250W Class A/B

- Paradigm Signature S8 v3 fronts

- Paradigm Signature SUB 1 subwoofer crossed over at 50Hz

- Cables: 4' 12G OFC Monoprice zip cord speaker cables, Radio Shack 3' RCA from CDP to preamp, stock power cables

I still don't have the sofa sectional in the room and room treatments, nor have I set up the SUB 1's programmable subwoofer room correction yet with PBK-1. Despite the bare room reflections, it sounds pretty decent still... Played my old Kind Of Blue SACD, Diana Krall's When I Look In Your Eyes, and Beck's Sea Change tonight. Really liking the subwoofer's punch on the Beck SACD. I'm an advocate for a good subwoofer... Good frequency response down to 20Hz is essential for hi-fidelity IMO.

Chat later... More boxes to pack tonight :-(.

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GUEST REVIEW & MEASUREMENTS: The Quantum HDMI Squeezer + ULTRA Cable: A look at HDMI cables.

By Keaton I. Goulden-Eyre III, Esq.

With Archimago overseas, he implored that I take a few moments to contribute to this most obscene of blogs (sorry dear readers, "objective" and audio do not mix in my worldview based on experience, wisdom, and my ears). Recall that many months ago, I brought you the review of Dr. Frank's "Best-Coaxial-Digital" SPDIF cable. I remain steadfast in my opinion of that fantastic interconnect!

A reminder - the introductory price is still available until December 31st! At $4999.99, it is a steal.

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The cellular phone rang - "How inconvenient!"

That was my initial thought the evening I heard about the cable being reviewed today. It happened in August as I was at my usual Las Vegas soirée with associates enjoying some Château Pétrus on my way to a Wolfgang Puck restaurant with a tender morsel of imported Wagyu in mind.

On the other end was Alfred Fitzgerald, LL.B. A member of my exclusive gentleman's club back home who could not wait to discuss an amazing audiophile find. Having had many deep conversations around our shared passion for audio reproduction, he knew that I would find his news intoxicating. He was correct.

It so happened that recently he was representing the interests of a client; Dr. Joseppi Maltzarelli, in the acquisition of a 30m yacht off the Florida Keys. He discovered that Dr. Maltzarelli was in fact a physicist who interned at CERN's Large Hadron Collider in 2005. His ground breaking theories on the vibrational qualities of quantum superstrings in the terahertz range drew applause but also envy from colleagues such that he decided to leave the "mainstream" physics community to become the chief scientific officer of a startup to leverage his theories and experience. The company: QuantaVibes Inc. based in Dushanbe, Tajikistan, aptly located just across the street from the Gurminj Musical Instrument Museum showcasing the history of stringed instruments.

Although the phone conversation was brief, I could not enjoy the succulent Kobe that night - lost in thought as I contemplated the potential of what I heard! I just had to call Dr. Maltzarelli upon my return home. I was almost unable to enjoy Céline Dion that evening!

After many E-mails and calls to QuantaVibes, I was finally able to track down Dr. Maltzarelli via satellite phone located somewhere off the coast of French Guyana in his yacht. It was a wonderful discussion; here is a good portion of our conversation:

ME: Good afternoon Dr. Maltzarelli. Thank you for taking my call.

JM: Absolutely Keaton, any friend of Mr. Fitzgerald's is a friend of mine. (Both laugh in approval.)

ME: I am curious my good fellow, whatever are you doing out at sea?

JM: The South Atlantic is beautiful this time of the year, my friend! I'm planning to sail down to Brazil and into Uruguay by the spring time where I will go inland to research the acoustic resonances of spiritual earthenware of the Amazonian peoples. Just a well deserved vacation after years of programming my supercomputer to calculate some Super Large Numbers involved in Superstring equations. The company is almost ready to ramp up production on what we believe will be the most significant HDMI audio upgrade in this generation - if not the most significant audio upgrade of all time!

ME: Amazing Joseppi. I'm perplexed however, how did a physicist of your calibre ever get involved in audio in the first place?

JM: You see, this is what happened. In 2005 when I was at CERN, I discovered that free-electron lasers were capable of inducing terahertz vibrations in the Superstring subequations as expressed using the derivative of the semiconductor Bloch equations. This caused quite a stir in the community because it meant that resonance effects created by this perturbation in high order space-time could fold down into our 3 spatial and single temporal dimensions! My colleagues were not able to handle this truth. They started a smear campaign decrying my theories and even went as far as to label me as mentally unstable!

ME: Terrible! Such close mindedness - they probably still believe the earth is flat! Was this why you left CERN?

JM: Yes, amico. I could not tolerate this final insult and left to pursue other avenues to realize the profound implications of this research. As to the second part of your question; audio was a natural fit for these equations. Like the strings of a violin, the Superstrings resonate in a natural harmonic. It just so happens that these harmonics precisely overlap with the audio spectrum when free-electron laser spectroscopy is activated at odd harmonic multiples. As a result, we can precisely tame the stray frequencies and decouple the thermionic energy flux passed across various equipment. My research pin pointed to the HDMI interface as one which could use this "taming" effect as a first foray into audio reproduction for the company.

ME: So, is it something to do with the HDMI interface's complexity?

JM: Precisely Keaton. You see, HDMI transports "bits" like how the Transporter in Star Trek transports matter. HDMI communicates using TMDS which sends those bits and nibbles with no respect for timing or integrity. This just shreds the musical information apart and artificially reproduces it at the other end! No wonder people experience horrific digititis, headaches, gout, sarcoidosis, gastrointestinal problems, and other forms of neurasthenia with this wretched interface for music. Is it any wonder how jittery the HDMI interface is?

ME: Impressive, doctor. So what is this product soon to be released to combat the problem?

JM: Soon, we will be releasing the QuantaVibe Quantum HDMI Squeezer and accompanying QuantaVibe ULTRA HDMI Cable. They should be purchased as a pair for synergistic effect. The Squeezer consists of an adapter for regular HDMI to micro-HDMI because supercomputer simulations demonstrated that the smaller size of the micro-HDMI interface precisely corresponded to the wavelength of these Superstring terahertz vibrations. The increased density of electron flow through the micro-HDMI connector accentuates the resonant-transduction effect by 323%. We've treated this device with a patent pending ultramicrochip which precisely aligns the resonances. Unfortunately this is a trade secret so I cannot elaborate any further.

ME: And how about the ULTRA Cable?

JM: We understand if an audiophile wishes to use a standard size HDMI-A connector or cannot modify their system to accept the micro-HDMI. It is more convenient but no matter how I load my equations for the terahertz wavelength, it is still a compromise due to the size of that connector. Nonetheless, we will be selling separately our ULTRA Cable which has some of the technologies incorporated in the microweave of the insulator. Again, I cannot divulge any further information on the technology itself lest I get in trouble with the CEO of the company. (Both laugh.)

ME: You know Joseppi, many insane "objectivists" will be very critical of these worthy products. What do you have to say to potential critics?

JM: Keaton, my friend, there will always be "haters" in this world. I faced many back at CERN under the guise of "peer review" and still get many thumbs down with my Facebook posts and criticism with interviews like this one probably. I do not expect everyone to appreciate the benefits. In our extensive testing in the lab, only those with excellent hearing, trained ears, truly high-end equipment, and impeccable taste in music can fully enjoy what we are about to produce. Furthermore, we are so convinced that the discriminating audiophile will love this product that we will be offering a 35-day guaranteed satisfaction or full refund! Absolutely no risk! I do not believe anyone can beat that.

ME: I have never heard of this kind of offer - 35 days! Now how about sending a set to me for a review?

JM: Absolutely, sir. I will have my people contact yours. I apologize Keaton, I have to go now, the fidanzata is calling... Never let the fidanzata wait...

ME: I absolutely understand. I look forward to the review sample and our next opportunity to converse. Perhaps at an audio show? I hope you find some hidden truths in the spiritual earthenware of the indigenous Amazonians.

With that, and good to his word, a package arrived from Tajikistan two weeks later. Neatly secured in its own black silk pouch I found this set of adapter and HDMI interconnect:

The workmanship was excellent. Black which matches my custom-designed HDMI DAC (connectors personally soldered by Nodko-san in Japan) with fabulously gold plated connectors. Directionality was clearly marked on the cable (not shown). I was informed by an associate at QuantaVibes that these are prototypes and the production units will feature gold embossed lettering on aerospace-grade titanium in place of the white label shown above.

The Quantum Squeezer is a mere 6cm (2.5") in length but tucked within it the full package of Superstring optimizations. At perhaps 15 gm in weight it was ethereally light - befitting of the level of technology! The ULTRA Cable is 12' in length and should be long enough for essentially any connection between your source and the HDMI DAC. This cable was optimized for music so do not expect it to carry nonsense HDMI 1.4 extensions like 3D or even 1080P to some sources*. Wow! Mind boggling how the potency of these optimizations were capable of limiting video transmission in the service of audio.

"Ultimate Smooth"
I immediately connected up the Quantum Squeezer and ULTRA Cable to the HDMI input of my UltraBook computer and custom DAC for a listen. (Remember, the Quantum Squeezer only works with the micro-HDMI port common on newer portable computers like laptops/ultrabooks.)

I don't know how Dr. Maltzarelli did it, but he did! I swear, the Herbert von Karajan & Berliner Philharmoniker Beethoven Symphonies played in my soundroom from my 16-driver 863 pound custom speakers with GIA FL grade diamond tweeters driven by special edition Nodko 8-Watt SET tube amps with a sparkle and clarity I had not thought possible. The strings were smooth like a well aged Highland single malt scotch whiskey or the hum of my newly acquired Jaguar F-Type V8 S. The timbre of each instrument resonated with a "note" beyond the vocabulary of the best Wine Spectator writer. This was the power of Superstring audio optimization!

The beautiful multi-layered vocals from Stephen Layton & Britten Sinfonia's version of Chorus: For Unto Us A Child Is Born (off "Handel's Messiah", 2009) almost dislodged me from my seat with the immensity of the recording venue's soundstage (St. John's, Smith Square, London). I had never heard the numerous voices with such definition. I could make out the fact that the tenor in the second row secretly picked his nostril at 1:23 into the track. Replacing the QuantaVibes cables with my AudioSearch Whiskey HDMIs ($300/3') demonstrated just how superior the QuantaVibes were and stepping down again to generic HDMIs ($20) resulted in either a collapse or dissolution of soundstage, leaving the voices decapitated, floating in space in one instance and the next congealed in an incomprehensible mess as if lying supine in a morgue. The joy was gone, the textures made bland, soulless. It was so obvious that anyone who could not tell the difference must be auditorily blind.

The same effect could be found with more pedestrian music. Consider the sitar on the Beatle's Norweigian Woods (off the 24-bit remaster of course). On the vast majority of HDMI cables (including very expensive ones I might add), they sound shrill, overly trebly, and ethnic. Through the Quantum Squeezer and ULTRA Cable, this instrument played with its full glory demonstrating George Harrison's connection with the numinous (perhaps aided by various hallucinogens?), altogether natural, at One, familiar. This level of sonic reproduction is priceless!

Finally, my luscious wife Candy wanted to participate in the audition.We cued up her favorite track from the Spice Girls - If You Wanna Have Some Fun. The soundstage exploded beyond the walls side-to-side, front-to-back; and the vocalization from the Girls were lined up beside each other - you could even discern the relative heights of these women! Candy squealed in delight exclaiming "I ain't heard it go so low before, Big Daddy!" Indeed, we had fun.

Readers, let me be perfectly clear about this. Forget all you have heard about "holographic" sound from inferior equipment. These cables offer HOLODECK sound. Miles Davis' spit could be heard and visualized dripping off his trumpet, Coltrane's sax keys rattled before my eyes, Elvis' hips gyrated in concert with his live performances, and Michael Jackson's lewd gestures beckoned beyond the grave off Thriller! Dare I say, this is the first time I have experienced digital sound even begin to achieve parity with my vinyl collection. Such was the presence. You know you want this.

Now, as per my agreement with Archimago, measurements are a pre-requisite for reviews of such gear on his blog (again, absurd). I lent him the QuantaVibes HDMI Squeezer and ULTRA Cable for a couple nights just before he went off on the plane. I'll be back in a moment after this unnecessary interlude...

Objective Analysis:

Okay, as Keaton said, I had the chance to measure his review cable with a couple other HDMI cables using the following setup just before I leave:

AMD A10-5800K HTPC with HDMI-A connector or ASUS Taichi with HDMI-D (micro-HDMI) --> Test HDMI cable --> Onkyo TX-NR1009 --> shielded RCA --> E-MU 0404USB --> shielded USB --> Win8 laptop for analysis

Cables tested:
1. HDMI "high speed" cable, ION branded, 6' long, used in my previous Onkyo DAC measurements. No problem with HDMI 1.4 functionality like 3D to HDTV. Cost - about $20.

2. Fancy 4m (~13') Energy branded HDMI with all the check boxes ticked for HDMI 1.4a. It's touted as the "Connoisseur" Series which I'm sure Keaton would approve of. High speed to "13.8Gbps" specified, ARC, 3D, ethernet, 4K... Even has a tag as seen in the picture with "Confirmation of HDMI ATC Testing" - ATC in this case means "Authorized Test Center" and for this cable, the center was "Dat Tran". Nice metal connectors and general cable build quality.

At $50, this is probably the most expensive cable I have and will be used between the Onkyo receiver and LG 3DTV in my new setup. Note that the upcoming HDMI 2.0 standard specifies data transfer rates up to 18Gbps but is backward compatible with high-speed cables so I hope this cable will do the job in the years ahead.

3. The review QuantaVibes Quantum HDMI Squeezer + ULTRA HDMI Cable. The HDMI Squeezer looks like a standard HDMI-A female to HDMI-D male converter capable of a 90-degree rotation. Although said to be "heavily modified", I do believe similar adapters can be found at the local Radio Shack :-).

The ULTRA Cable is "standard speed" - tested to be OK with 1080P with my TV and the ASUS Taichi ultrabook, but NOT fast enough for 3D video off my Panasonic BMP-TD220 Blu-ray player.

Starting with the usual RightMark measurements, here's the summary (all done at 24/96, HDMI WASAPI driver):

 

Frequency Response

Noise level

No difference folks! Frequency response, noise level, distortion levels appear indifferent to the HDMI cables used.
 
Let's look at jitter with the usual Dunn J-Test:

Hmmm, what's this? The QuantaVibes spectrum is more jittery - especially noticeable with the 24-bit condition. However, notice what's happening here. Both the ION and Energy cables are being measured off the standard HDMI connector whereas the QuantaVibes is off the ASUS Taichi laptop's micro-HDMI port. What happens if we use the "HDMI Squeezer" converter but with the fancy Energy HDMI cable instead?

Voilà, the jitter spectrum now looks like the one above with the QuantaVibes ULTRA HDMI cable. Basically what is demonstrated here is exactly what I saw with the TosLink, USB, and coaxial digital interfaces. The jitter spectrum is a function of the sending and receiving device. The cable itself does not change the pattern; in this case, the little ASUS Taichi ultrabook tends to show more jitter than the HTPC AMD A10-based computer. Whatever HDMI cable is used does not change the jitter pattern (although I suppose one could wonder whether the HDMI-A to micro-HDMI adapter has an effect; not likely).

Bottom line from the objective side: No evidence that HDMI cables make any difference to standard measures of frequency response, distortion, noise floor/dynamic range of the DAC (Onkyo TX-NR1009 in this case). Jitter remains a function of the active devices, not a property that varies with the passive cables themselves (at least within the reasonable lengths tested up to ~13 feet). I'm happy to be proven wrong if anyone else has good data especially with less jittery DACs than this receiver.

I am therefore at a loss as to Keaton's enthusiasm around this product.

Back to Keaton for his conclusions.
 

Keaton's Konclusions:

Bollocks, more squiggles from Archimago... Yet again, measurements remain insensitive and unable to achieve the resolution of my 73-year young experienced ears. Hence useless and invalid for audio evaluation. We all know that everything matters, even more so digital cables because there isn't such thing as digital according to these enlightened gentlemen. HDMI is of course the worst of all the digital connections for audio (some other enlightened gentlemen at Audio Asylum agree) which makes it so much more important that we spend more money on ensuring perfect digital transmission.

As a side note, I connected the ULTRA HDMI Cable by itself to my Blu-ray player and 85" 4K TV. I swear, the image was more stable, colors brighter, and the actors moved so smoothly and with such poise that B-movies seemed Oscar worthy. Likewise, the audio-video synchronization was even better with these cables that I wondered how I managed to watch movies without them! Here again, the power of jitter-free sympathetic Superstring resonance at work. Indeed, I will be ordering a separate set of ULTRA's just for the Blu-ray player when the final product is released. Nonetheless, I feel that without the HDMI Squeezer, the synergism just wasn't there. The sound didn't reach as deep, the trebles didn't quite touch the heavens; without doubt, you need the full set!

You likely are aware that so far I have not said how much these high-tech devices will be sold for. I was told the company is still perfecting the quality control due to the precise manufacturing standards and complexity of the patent pending process. Expectations are that both the HDMI Squeezer and ULTRA Cable will be priced as a set at the $3000 mark. By itself, the ULTRA Cable will be around $2000. Mere pocket-change for this level of sonic/video revelation - I bet your power cords costs about just as much and they only have 3 individual wire lengths inside at most, and require less precise shielding! This is very comparable to other high-end HDMI cables such as these or these or these especially given the improvements on the quantum scale!


With this premier product from QuantaVibes, I am confident that we will 'hear' more from this up-and-coming newcomer to the high fidelity audio scene. I have a strong feeling that Dr. Maltzarelli's research into Amazonian earthenware will yield many revelations into audio resonances for upgrading the sound room. It was with supreme regret that I had to return the review cable back to QuantaVibes after 3 weeks of audio bliss for fear of industrial espionage. Currently awaiting their formal release with bated breath and ample liquidity in hand.

Until next time; Magico wishes and Burmester dreams.

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* This cable is rated as "Standard HDMI".

Ed: And so ends the digital audio cable measurement quadrilogy. That is, until yet another digital audio interface shows up with fancy cable claims... Enjoy the music till then :-).

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MEASUREMENTS: ONKYO TX-NR1009 as HDMI / SPDIF DAC... Are AV Receivers any good?

The rat's nest.

Running separate components like multichannel processors/preamps to monoblock amplifiers are generally considered the ideal, "cost no object" approach to home theater. In the real world, cost and space are considerations and AV receivers become the "Jack-of-all trades" central device that most of us have in the home theater setup. But like the proverbial "Jack", it's useful to also consider the second part of that saying... Just how bad  is he also "the master of none"?

In the last installment, we looked at passing an analogue audio signal through the Onkyo and found that noise can be an issue. Today, I want to demonstrate the quality if we were to just use this device as a DAC - a look at the digital portion. Some natural questions arise - how well did the designers shield noise from getting in (especially in light of the high analogue noise measured previously)? Is the jitter through the use of HDMI "bad" (compared to TosLink and coaxial S/PDIF)? How does it compare to other stereo DACs?

Based on the Onkyo specs sheet, the TX-NR1009 uses the TI PCM1690 6-channel + PCM1789 2-channel DAC chips. Both are rated as 113dB SNR. These DAC chips are often found in consumer AV receivers and are lower spec'ed than most stand-alone DACs like the TEAC UD-501's PCM1795 with >120dB SNR. Of course, you cannot just look at this specification and judge the quality of a DAC. Much depends on the analogue circuitry around that DAC so the measured results are more useful than just looking at the components individually.

Setup:

As usual, for the sake of full disclosure and opportunity to repeat/verify, here is the setup for these measurements:

Win8 AMD A10 "Trinity" HTPC --> HDMI/TosLink/coaxial cable --> ONKYO TN-NR1009 front stereo "pre-out" --> shielded RCA --> E-MU 0404USB --> shielded USB --> Win8 laptop
CM6631A device used for asynchronous USB --> coaxial / TosLink conversion duties.

HDMI driver: default AMD WASAPI. I used JRiver for playback.

Since I want to check the performance in a more "naturalistic" fashion, I made sure the TV was connected and on as well as my Blu-ray player (Panasonic BMP-TD220). Remember that in my previous post, plugging in the HDMI TV cable added significant noise to the analogue pass-through. All results were made with the Onkyo in "Pure Audio" mode to defeat any audio DSP/bass management.

HDMI cable: A decent looking 6' length capable of high speed HDMI (officially rated as HDMI 1.3 but fine with my HDMI 1.4 3D TV), brand named "ION" that I purchased for something like $20 about 2 years back at a local computer/supplies store.

TosLink and coaxial SPDIF cables I'll be using for comparison are the "Acoustic Research" branded 6' lengths I measured previously (see links for details).

Results:

As usual, I ran the output through my digital oscilloscope first to have a look:

Here is a 0dBFS 1kHz square wave sent through the HDMI and measured off the front stereo "pre-out" RCAs. Not bad - good square waveforms with excellent channel balance (sorry about the pixellation, usually screenshot looks better than that). With the receiver volume set to the "reference" of 85 (there is a little popup on the front screen when you hit 85 that correlates to the 0dB THX reference level) and in "Pure Audio" mode, the peak voltage is around 2.3V.

Here's a 24/44 impulse response:

Good linear phase impulse response, nothing fancy here. Absolute polarity also maintained by the Onkyo.

I. RightMark:
As usual, I used RightMark to look at the measured dynamic range, noise level, distortion levels; here's the summary for HDMI at the various bit depths and sample rates:

As you can see, I've also included for comparison the results at 24/96 for the Squeezebox Transporter and TEAC UD-501 (unbalanced outputs) - two of the best measuring DACs I've tested here with the same hardware/software.

Clearly the Onkyo is capable of hi-res with >16-bit dynamic range. With 24-bit data, it can do ~109dB dynamic range which equates to just over 18-bits! Not as good as the dedicated audio units like the Transporter or TEAC but pretty darn good for an AV receiver! This result is about equivalent to the AUNE X1 and ASUS Essence One using unbalanced RCA output - however, those DACs had better distortion numbers.

Some graphs to review from the 24/96 dataset:

Frequency Response

Noise Level

THD

The Onkyo rolls off a bit more in the high end, a little more noisy, and notably more harmonic distortion.

For fun, here's the spectrum off the Onkyo playing 24/192:

Yup, capable of 24/192 although the roll-off on the high end is obviously earlier than the TEAC UD-501 (Onkyo drops -3dB at 50kHz).

I was curious if the SPDIF (TosLink and coaxial) inputs measured just as well:

Yup. They all look pretty good. The graphs all look identical except for slightly more high end roll-off with the HDMI interface compared to the SPDIFs - not sure why.

II. The 1kHz -90.3dB "Microscope"

With the dynamic range >16-bits, this test should be no problem for the Onkyo (HDMI input).

That looks very nice given that many very expensive DACs are not even capable of this degree of resolution! Again, this is an AV receiver! As I previously posted, even recently released DACs like the Wadia 121 Decoding Computer is incapable of this resolution.

III. J-Test for Jitter

As usual for my DAC tests, let's have a look at the Dunn J-Test spectra for both 16-bit and 24-bit signals. Here is the summary using the 3 digital inputs - HDMI, coaxial SPDIF, and TosLink SPDIF:

As you can see, the Onkyo is quite jittery in general whether HDMI or the other SPDIF interfaces. Although quite similar, I am somewhat surprised that the sidebands were more pronounced for the coaxial digital input! For comparison, here's the Transporter and TEAC:

Although the scale and dimensions are a little different, one can certainly appreciate just how jittery the Onkyo is compared to the others especially with the 24-bit signal. From this data, we see that the Onkyo itself has more jitter as a whole; specifically it's not any worse with the HDMI interface. We'll talk about jitter again in a little bit...

IV. Does sending a 5.1 channel signal degrade the measured performance?

I thought this would be interesting to check out. I left the RightMark test signal as the two front channels and added some AC/DC "Thunderstruck" into the center, rear, and LFE channels played back in JRiver as a multichannel FLAC through HDMI.

Beautiful ain't it?! The idea is to see if driving 6 channels (5.1) at the same time through the HDMI cable into the Onkyo's DAC will change the audio quality... For example, doing this might increase the noise floor, or perhaps worsen channel crosstalk since we've tripled the number of audio channels being processed.

Frequency Response

Noise Level

As you can see, there's very little difference whether 2 channels are playing or 6 channels. Great to see! Essentially no frequency response or crosstalk difference. However, there is a very small increase in noise level when playing multichannel... IMO audibly insignificant but measurable.

Summary:

Here you go folks! That's how a higher-medium end "modern" AV receiver measures as a stereo DAC. Of course, each model will be a bit different, but I suspect similar tiered receivers from Pioneer, Denon, Integra, Yamaha, H/K, Anthem, etc... should be comparable (won't know unless someone tests it out). Note that most magazines like Sound & Vision will measure receivers but usually in the context of power output and flatness of frequency response rather than on the accuracy of the digital-to-analogue conversion as I did here.

In some ways I am impressed and in other ways the results were as expected.

I was impressed by the low noise and very good dynamic range for example. To achieve almost 110dB in the audible spectrum is quite something especially considering the complexity of an AV receiver with all the potential electrical noise sources inside the box! The accuracy of the 16-bit -90.3dB waveform looks excellent; something which only the better stereo DACs or CD players would have been able to accurately reproduce a decade back. Likewise, the fact that the measurements remained excellent even with 6 channels being processed concurrently and only measuring about 1dB difference in the noise floor again demonstrates the engineering quality. Given the results I found previously with HDMI noise polluting the analogue input, I'm guessing that Onkyo put more attention in optimizing the digital side which makes sense since most people will be connecting digital inputs for multichannel sound.

As for the more "expected" results, let's talk about jitter...

A few years ago in 2009 this message came over the 'Net which I remember made quite an impression on me around how "bad" HDMI is as an audio interface (supposedly from Hi-Fi News & Record Review / Miller Research):

(I didn't notice it at the time, but that Denon AVR-3803A was a typo - the 3803 has no HDMI. It's actually the 3808.)

Later, a more comprehensive message appeared:

Hmmm, it looks like HDMI jitter can be cleaned out after all (eg. Arcam, Classe, Pioneer)! It's about the implementation, not necessarily the interface itself. If you read around these posts, one also finds that the jitter value and subjective sound quality do not necessarily correlate.

Let's think about the J-Test and what was found in measuring the Onkyo for a moment. The Dunn J-Test is a synthetic test of data jitter first published by the late Julian Dunn around 1994 which (in the 24-bit 48kHz version) superimposes an undithered LSB 250Hz square wave over a primary 12kHz -3.01dBFS sine wave which is of course an exact 1/4 of the sampling rate. This superimposition stimulates the effect of subtle timing inaccuracies (jitter) which can be demonstrated as accentuation of the sidebands measured in the spectral graphs.

Remember that this test is synthetic and stimulative. What you see measured is not something you're probably ever going to "hear" in real music! The noise floor is not going to be down to the last bit in 16-bit audio and essentially impossible with recorded 24-bit audio (unless it's purely computer synthesized music). Also, jitter is more pronounced in the higher frequencies (11kHz and 12kHz are used as the primary signals in the J-Test). Realize that the human hearing sensitivity is well on its way down by 5kHz (as can be seen by the Fletcher-Munson Curves). Furthermore, if we specifically look at the Onkyo's J-test spectrum, the most pronounced side bands are about -90dB below the primary signal. To make matter even less worrisome is that the tall sidebands are all +/-250Hz around the primary signal and the audibility would be masked even if one did have awesome auditory acuity at 11/12kHz and could hear a signal 90dB down! This is also why I feel adding up all those sideband peaks and calling it a number (whatever picosecond or nanosecond) is really not all that useful when it comes to audibility.

What I'm trying to say is this... Tests like the J-test can demonstrate that jitter is a real phenomenon. Engineers should pay attention to it when designing hi-fi equipment. A discerning audiophile should be aware of it and if able to, can measure it themselves and decide if the engineer did a good enough job. However, IMO, to say that jitter is somehow audible at these kinds of levels I think would be impossible. In fact, unless the jitter were ridiculously high (like Track 26 from Stereophile Test CD 2, where an insanely simulated 10ns sideband is inserted +/-4KHz around the 11kHz primary - again totally synthetic), the concept of jitter significantly deteriorating sound quality I believe is utter nonsense in the real world. That some companies would even consider using jitter as a reason for putative significant audible differences between passive "components" like cables is just not credible!

I had a listen to the Onkyo's output over the last few nights with some familiar music - Ella Fitzgerald "Sings The George & Ira Gershwin Song Book", Grateful Dead "American Beauty", and Keb' Mo' "Just Like You". Also had a listen to Sting's new album "The Last Ship". They all sounded nicely rendered as they should with a good DAC. Great details with my older Paradigm Reference Studio 80 v2's which will be my rear speakers in the new sound room. The wife and I both enjoyed Sting's "The Night The Pugilist Learned How To Dance" - cute.

So, even though the AV receiver might be the "Jack-of-all-trades", at least in this specific instance with the Onkyo TX-NR1009 as an HDMI DAC, he might not be a "master" at it, but I'd say he's a pretty decent tradesman :-).

Well, unless I dig up something else to report, I'm likely "going dark" for the next month as I head off overseas for some work and then the big move to the new home. I'll be sure to post some pictures in time... Enjoy the music everyone!

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MEASUREMENTS: Separate vs. AV Receivers (Emotiva XSP-1 vs. Denon AVR-3802 vs. Onkyo TX-NR1009) as Analogue Preamp.

Okay, so maybe I'm being a bit too dramatic using that epic battle between Godzilla and Rodan above :-).

With the recent acquisition of the Emotiva XSP-1, I wanted to see just how well a separate pre-amp with audiophile design in mind stacks up against something more ubiquitous like the AV receivers out there. Remember that a preamp at its core has very basic functionality - it allows switching of the source and volume control by adjusting voltage gain on the output. The essential difference between a good preamp versus poor one (beyond features, ergonomics, remote control quality, etc...) is how well it maintains a high signal-to-noise ratio (SNR). If you supply a high resolution line level DAC output, you want to see that signal come out of the preamp with as much resolution as possible; this demands that the preamp introduce as little noise as possible.

Is there good evidence that spending money on a good analogue preamp will result in more accurate music reproduction? Let's find out in this installment...

First, let me introduce the contenders today:

Emotiva XSP-1:

Currently the highest quality Emotiva preamp out. The claim to fame is the differential design for balanced operation. It provides 2 balanced inputs along with a host of unbalanced RCAs. Volume control is through a digitally controlled, analogue resistor network. For this test, I will not be using the analogue bass management or tone controls that could affect signal presentation / quality. SNR for this device is rated at >110dB across the board for both RCA and XLR operation.

Denon AVR-3802:
A 7.1 channel "classic" from the decade when SACD and DVD-A were starting life and home theater lovers started seriously investing in discreet surround receivers with Dolby Digital and DTS (as opposed to the matrix surround of previous Dolby Pro Logic receivers). Analogue 7.1 channels input available. I bought this unit back in early 2002. Though not the highest end back then, it wasn't cheap (I think I paid almost $2000CAD). I don't remember the results of actual 3rd party testing but the rated amplifier power is 105W into 2 channels at 8ohms with 0.05%THD.

Analogue input SNR is rated at (only) ~86dB based on the table in the manual. For the sake of measuring the best possible audio output, all measurements will be performed through the CD input in "DIRECT" mode which bypasses all processing including tone controls and bass management. Measurement will be off the front (stereo) channels of the 7.1 "pre-out" analogue outputs.

ONKYO TX-NR1009:

My new receiver mentioned in the previous post. Capable of 9.2 channels processing with 7.1 analogue external inputs. Again, not the most expensive in the Onkyo line but certainly in the upper end of the previous generation released in mid-2011. Amplifier is capable of more power than the Denon with a rating of 135W into 2 channels at 8ohms with 0.08%THD. Sound & Vision measured it as 145W into 2 channels at 8ohms with 0.1% distortion. Line level SNR rated at 110dB.

I'll measure it through the analogue CD input in "Pure Audio" mode where all extraneous audio processing is turned off. Likewise, it's supposed to quiet the video circuitry and even the front LED indicators and display are turned off. I will measure from the front (stereo) channels of the 9.1 "pre-out" analogue output.

Firmware was updated to the latest version as of September 2013 - 1131-1399-0211-4108.

Setup:

 

First, I just want to discuss the general setup. The main thing I wanted to know was just how much resolution was maintained with the signal going through the preamp and look/listen to the results through a variety of levels standard across each device.

For the TEAC UD-501 DAC at 24/96 (which to me is the sweet spot) using the "SHARP" digital filter measured the following way:

HTPC (AMD A10 "Trinity") --> shielded USB (Belkin gold) --> TEAC UD-501 --> shielded RCA --> E-MU 0404USB --> shielded USB -->  Win8 laptop

we get these results:

The hope of course is that when we pass the above signal through the pre-amp, there will be minimal loss in resolution (noise level remains low around -113dB, and no change to frequency response to suggest "coloration" of the sound). In my previous TEAC measurements, I noted that the XLR output was too "hot" for the E-MU 0404USB without volume attenuation which drops the resolution. My guess would be that the noise level drops to less than -116dB. I will measure the XLR output from the Emotiva XSP-1 and see (it's the only device out of the 3 capable of balanced operation).

 

Using the digital oscilloscope, I found the following correlation between peak voltage output from each preamp device (accurate to <0.05V) and the volume control setting (using the TEAC RCA or XLR input of course):

Nice to see the volume control accuracy of each device - every halving of output peak voltage corresponds with a 6dB decline of the volume "knob". Notice that the Emotiva and Denon are using a relative system of volume control (dB below 0dBFS) and the ONKYO is set to an "absolute" measure between 0 to 100.

The setup incorporating the pre-amp in-line therefore looks like this:
HTPC (AMD A10 "Trinity") --> shielded USB (Belkin gold) --> TEAC UD-501 --> shielded RCA/XLR --> Pre-Amp device --> shielded RCA/XLR --> E-MU 0404USB --> shielded USB -->  Win8 laptop

Results:

I. Emotiva XSP-1 RCA:

Without further ado, here is what the Emotiva looks like with the unbalanced RCA setup:

Frequency Response

Dynamic Range

This looks really good. At 2V peak output, the dynamic range at 111dB is very close to the "ideal" (113dB directly from the TEAC). Notice a very small amount of roll-off in the high end when using the Emotiva. Also as expected, when the volume is reduced (2V --> 1V --> 500mV --> 250mV), the signal-to-noise ratio goes down and we see a concomitant reduction in the dynamic range and rise in noise level.

II. Emotiva XSP-1 XLR:

Let's have a look at the XSP-1 operating in a balanced configuration:

Frequency Response

Dynamic Range

Well folks, proof that if you want absolute fidelity, you really need to squeeze out those last few dB's down below 110dB with balanced XLR cables! Irrespective of whether you can hear it or not :-)!

Seriously, these are some fantastic measurements. As I said previously, unfortunately, I don't have direct measurements for the TEAC's XLR output. When passing the XLR output from the TEAC to the Emotiva pre-amp, the results at 2V peak volume coming out of the Emotiva slightly exceeds the direct RCA output from the TEAC DAC across the board from noise level to distortion levels to even lower stereo crosstalk.

The high frequency roll-off is less than with RCA. Notice just how clean the dynamic range graph looks as well through XLR cables. Fantastic.

III. Denon AVR-3802 RCA

Now we get into the AV receivers:

Frequency Response

Dynamic Range

Remember, I am measuring the Denon in "DIRECT" mode with all audio processing including bass management turned off (front stereo speakers set to "Large" for the sake of completeness). Not unexpectedly, these results are clearly a step down from the Emotive XSP-1. With a dynamic range of ~96dB at 2V, the Denon is capable of passing through 16-bit CD resolution but nothing more.

Roll-off above 20kHz is similar to the Emotiva's unbalanced mode but worse than the Emotiva below 100Hz with a -1dB bass roll-off at 20Hz.

IV. ONKYO TX-NR1009

Finally, let us have a look at what approximately a decade of advancement (between this and the Denon) in AV receiver technology can do:

Frequency Response

Dynamic Range

With the ONKYO in "Pure Audio" mode, no video processing at all, HDMI and video inputs all disconnected... Wow! That's very impressive IMO for a machine that's a "jack of all trades". In fact, these results are almost the same as the Emotiva XSP-1 functioning in unbalanced mode!

As excited as I am about those results above, a modern AV receiver is meant to process HDMI and be connected to a TV. This receiver has a HDMI "passthrough" which is essentially always in operation and for most people, it would not be left in "Pure Audio" mode with all the video gear disconnected. As such, look what happens when I connect my LG 55LW5600 TV (55" passive 3D, LED TV from 2011) to the ONKYO and repeated the measurements:

Frequency Response

Dynamic Range

Ugly, my friends... Clearly having the TV HDMI connected has injected very significant amount of noise in the system! Dynamic range has dropped to ~80dB across the board (equivalent to 13-bits). Notice a very strong 60Hz mains hum which is even showing up in the frequency response graph... What is happening here is that I'm seeing the effect of ground loops. There are ways to overcome this of course. For example, using a 3-to-2 prong adapter to disconnect the TEAC DAC from ground resulted in the following:

Frequency Response

Dynamic Range

About 10dB improvement just by doing this. For now, I'm not going to bother isolating the problem further (I'll be moving house in about a month!) but suffice it to say that in a receiver setup with complex component interconnections, be very careful of noise polluting the analogue output as demonstrated above. Ground loops are very common especially with TV systems where ethernet and coaxial cables are often connected to the TV/receiver creating a number of potential ground points beyond the individual device plug-ins to the wall.

Summary:

 

So there you have it. The Emotiva XSP-1 measures as a very capable pre-amp unit with excellent resolution especially when used in a balanced configuration. There was barely any loss through RCA and the XLR performance is beyond the E-MU 0404USB's measurement capabilities. Note that in all these tests, I'm just using generic "Radio Shack" type RCA connectors and the XLR cables are inexpensive Monoprice brand. No reason for spending money on expensive cables when these kinds of results can be obtained with standard decent interconnects.

In "Pure Audio" mode without the HDMI system connected, the ONKYO performed excellently. It bested the 12-year old Denon AVR-3802 handily and is essentially neck-and-neck with the Emotiva in an unbalanced configuration. However, beware of the potential noise pollution and ground loops once you plug in all sorts of things into these receivers (like your fancy big screen TV)!

A little while back, I spoke about how music sounded better through the Emotiva XSP-1 compared to using the Denon as pre-amp. These results are supportive of my subjective impressions (I'm showing >10dB dynamic range difference and bass roll-off differences between the two). As for the ONKYO, it does sound much like the Emotiva as a stand alone audio device. Since I will be listening primarily with the ONKYO as a HDMI DAC (either from the computer or through Blu-ray player), for me the digital audio performance is much more important than the results I show here from the analogue input.

Music this evening:
My kids enjoyed Les Misérables (the movie) and really love to listen to it in the car on the way to school... My favorite recording of this is the recent 25th anniversary UK Tour cast from 2010's performance called "Les Misérables Live!" - certainly much better singing than Hugh Jackman and Russell Crowe!

I've got another trip coming up at the beginning of November and then the house move by the end of November. I hope to put up some results of the ONKYO as HDMI DAC before I go. Until next time... Enjoy the tunes...

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