Sony DMP-Z1 digital music player Measurements

Sidebar 3: Measurements

I measured the Sony DMP-Z1 with my Audio Precision SYS-2722 system (see the January 2008 "As We See It") using test-tone files copied to the Sony's internal storage. The DMP-Z1's battery was fully charged before I began testing, and I measured the player's performance at its single-ended headphone jack in Direct Source mode, which bypasses the DSP functions.

Apple's USB Prober utility identified the DMP-Z1 as "PLAYER" from "Sony" with serial number "1045A0A1000727" and confirmed that its USB port operated in the optimal isochronous asynchronous mode. Apple's AudioMIDI utility revealed that, via USB, the DMP-Z1 accepted 16-, 24-, and 32-bit integer data sampled at all rates up to 384kHz. The Sony's maximum output level at 1kHz was 2.02V in normal mode, 4.0V in High Gain mode. The output impedance was a low 5.5 ohms from 20Hz to 20kHz. The output preserved absolute polarity (ie, was noninverting).

I examined the DMP-Z1's behavior in both the time and frequency domains with each of its six reconstruction filters. The Sharp filter's impulse response was a conventional time-symmetrical linear-phase type (fig.1), while the Short Delay Sharp filter's impulse response (fig.2) was minimum-phase, with all the ringing following the single high sample. The Short Delay Slow filter's impulse response (fig.3) was also minimum-phase, but, as its name implies, very short. The impulse response of the Low Dispersion Short Delay filter was a hybrid type identical to that of the Pro-Ject Pre Box S2 Digital's Hybrid filter2 (fig.4), while that of the Slow filter was an extremely short linear-phase type (fig.5). The Super Slow filter had a time-perfect impulse response with no pre- or post-ringing (fig.6).

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Fig.1 Sony DMZ-1, Short Delay Sharp filter, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).

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Fig.2 Sony DMZ-1, Short Delay Sharp filter, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).

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Fig.3 Sony DMZ-1, Short Delay Slow filter, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).

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Fig.4 Sony DMZ-1, Low Dispersion Short Delay filter, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).

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Fig.5 Sony DMZ-1, Slow filter, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).

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Fig.6 Sony DMZ-1, Super Slow filter, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).

With white noise sampled at 44.1kHz, the Sony's output with the Sharp and Short Delay Sharp reconstruction filters rolled off above 20kHz (fig.7) magenta and red traces), reaching full stop-band attenuation at 24kHz. The aliased image of a 19.1kHz tone at 0dBFS (cyan, blue) was suppressed by 101dB, and the second and third harmonics of this tone lay below –90dB (0.003%). With the Low Dispersion Short filter, the ultrasonic output rolled off slightly less quickly (fig.8), with the aliased tone suppressed by 44dB.

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Fig.7 Sony DMZ-1, Sharp filter, 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.).

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Fig.8 Sony DMZ-1, Low Dispersion Short filter, 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.).

The Slow and Short Delay Slow filters behaved identically in the frequency domain, with a rolloff that starts in the top audio octave, lies at –3dB at 18kHz, but doesn't reach full attenuation until 38kHz (fig.9, magenta and red traces). The aliased tone at 25kHz is suppressed by just 12dB with this filter. The Super Slow filter rolls off very slowly, with the response down by 1dB at 15kHz, and nulls at 44.1 and 88.2kHz (fig.10, red and magenta traces).

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Fig.9 Sony DMZ-1, Slow filter, 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.).

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Fig.10 Sony DMZ-1, Super Slow filter, 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.).

Channel separation was superb, at >92dB in both directions from 20Hz to 20kHz. As expected with a battery-powered device, the DMP-Z1's low-frequency noise floor was both very clean and very low in level (fig.11). Increasing the bit depth from 16 to 24 with a dithered 1kHz tone at –90dBFS lowered the noise floor by around 16dB (fig.12), implying resolution of close to 19 bits. Repeating this analysis with a dithered 1kHz tone at –120dBFS gave a superbly clean spectrum, with no harmonics visible above the low noise floor (fig.13). With undithered data representing a tone at exactly –90.31dBFS (fig.14), the three DC voltage levels described by the data were well resolved, with a symmetrical waveform. A very slight (25µV) DC offset can be seen in the right channel (red trace).

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Fig.11 Sony DMZ-1, spectrum of 1kHz tone at 0dBFS with 24-bit data (left blue, right red) (20dB/vertical div.).

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Fig.12 Sony DMZ-1, spectrum with noise and spuriae of dithered 1kHz tone at -90dBFS with: 16-bit data (left channel cyan, right magenta), 24-bit data (left blue, right red) (20dB/vertical div.).

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Fig.13 Sony DMZ-1, spectrum with noise and spuriae of dithered 1kHz tone at -120dBFS with 24-bit data (left blue, right red) (20dB/vertical div.).

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Fig.14 Sony DMZ-1, waveform of undithered 1kHz sinewave at -90.31dBFS, 16-bit data (left channel blue, right red).

Harmonic distortion was very low, with the second harmonic the highest in level, at just below –90dB (0.003%, fig.15), accompanied by the third harmonic at –106dB (0.0005%). With a full-scale mix of tones at 19 and 20kHz and the Sharp and Short Delay Sharp filters, the noise floor was clean and the second-order difference product

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Fig.15 Sony DMZ-1, spectrum of 50Hz sinewave, DC-1kHz, at 0dBFS into 600 ohms (left channel blue, right red; linear frequency scale).

at 1kHz lay at an extremely low –106dB (fig.16). With the relatively slow ultrasonic rolloffs of the Slow and Short Delay Slow filters, the aliased images of the fundamental tones can be seen at high levels (fig.17) but were much lower in level with the Low Dispersion Short Delay filter (fig.18). They are hardly suppressed at all with the Super Slow filter (fig.19), and several other aliasing products make appearances in the audioband.

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Fig.16 Sony DMZ-1, Sharp filter, HF intermodulation spectrum, DC-30kHz, 19+20kHz at 0dBFS into 600 ohms, 44.1kHz data (left channel blue, right red; linear frequency scale).

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Fig.17 Sony DMZ-1, Slow filter, HF intermodulation spectrum, DC-30kHz, 19+20kHz at 0dBFS into 600 ohms, 44.1kHz data (left channel blue, right red; linear frequency scale).

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Fig.18 Sony DMZ-1, Low Dispersion Short Delay filter, HF intermodulation spectrum, DC-30kHz, 19+20kHz at 0dBFS into 600 ohms, 44.1kHz data (left channel blue, right red; linear frequency scale).

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Fig.19 Sony DMZ-1, Super Slow filter, HF intermodulation spectrum, DC-30kHz, 19+20kHz at 0dBFS into 600 ohms, 44.1kHz data (left channel blue, right red; linear frequency scale).

When I tested the Sony DMP-Z1 for its rejection of word-clock jitter using undithered, 16-bit J-Test data sourced from both its USB input and its internal storage, the odd-order harmonics of the low-frequency, LSB-level squarewave were all at the correct levels (fig.20, sloping green line). Unlike some other D/A processors I've recently tested, the spectral spike that represents the high-level tone at one-fourth the sample rate was very narrow at its base, suggesting very low random low-frequency jitter. This excellent jitter rejection was repeated with 24-bit data (fig.21).

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Fig.20 Sony DMZ-1, Sharp filter, high-resolution jitter spectrum of analog output signal, 11.025kHz at -6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 16-bit data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, Ò3.5kHz.

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Fig.21 Sony DMZ-1, Sharp filter, high-resolution jitter spectrum of analog output signal, 11.025kHz at -6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 24-bit data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, Ò3.5kHz.

Sony's DMP-Z1 turns in superb measured performance, indicative of equally superb analog and digital audio engineering.—John Atkinson


Footnote 1: See fig.6 here.
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COMMENTS
dc_bruce's picture

I guess for the audiophile who has everything, this is it. But, at this price, there are a lot of nice DACs available. Moreover, as always seems to be the case with Sony, they're a week late to the party. It seems that few people are playing files these days; they're streaming.

Finally, Mr. Atkinson's report on the sonic effects of the myriad of filters offered by this device permanently buries the notion that digital sound is perfect. If using two different filters to play back the same digital file through the same electronics yields two different sounds, then they both can't be "right." Maybe neither is. So, it seems with digital we have merely traded the imperfections of analog for a different set of imperfections; we may not have gotten "closer to the source," whatever that is.

I grant only that digital generally is more convenient than analog and, perhaps, less perishable.

Archimago's picture

It's not so much about "perfect" or "imperfect" digital. It is just that the company wants to give people choice.

The best technical filter with least imaging artifact, best frequency extension, and no phase shift is the linear phase "Sharp Filter". If people likes the sound of the others, so be it. Many companies are just playing around with giving people a choice... That's fine.

Having said this. Show me a blind test that these are significantly audible :-). I know audiophiles don't like the concept of blind tests, sadly.

ednazarko's picture

Everything that's technology is a bundle of tradeoffs and compromises. Price, weight, size, capacity, sure, but there are other tradeoffs that often the manufacturer decides for you - like filters, sound signature, DSP. I always like to have control over a few of the tradeoffs that affect how things sound, since speakers and headphones have their own set of tradeoffs.

The notion that there's some pure rendering of a recoding always makes me giggle a little. I've been in studios watching recording, where the whole goal is to get as pure and controlled capture of each instrument as possible. Sound baffles, soundproof rooms, close mics. When you listen to that in playback, it sounds truly terrible - artificial, almost like it came from an electronic instrument and not a saxophone or piano. "Dry" is the term of art. Then during the mixing and production, reverb and decay and other sound shaping things get tinkered with to try to get it to sound more realistic to normal ears that are used to hearing instruments playing in spaces that affect the sound.

Other than live albums recorded outside of studios, without close mic placement, anything you hear has a significant amount of tinkering added to the raw recording.

BillBrown's picture

I don't want to argue about blind testing (I largely agree with JA's oft-stated opinion), but you shouldn't assume that none of us are interested in it.

While acknowledging it as single-blind test and N = 1, I had listened to various filters open-mindedly and begun to form an impression. I was comparing in Audirvana a conventional steep, linear-phase one with a very shallow one that the designer of iZotope had described as quite similar to Ayre's.

I tested my acute-eared, music-loving 20 year-old to some of his favorite selections without telling him what I was comparing or what to listen for. He heard a difference and used adjectives similar to the ones I had been thinking. He didn't hear anything untoward, nothing to suggest artifacts.

Bogolu Haranath's picture

As an example ....... Look at the frequency response measurements of dCS Bartok DAC, recently reviewed by Hi-Fi News ...... The effects of various filters :-) ..........

Bogolu Haranath's picture

Another recently reviewed Esoteric DAC, rolls-off -3.2 db at 20 KHz, by Hi-Fi News measurements :-) .........

Bogolu Haranath's picture

One more ....... Pioneer UDP-LX800 universal player offers a 'slow roll- off' filter, which rolls off -5 db at 20 KHz, by Hi-Fi News :-) .........

Bogolu Haranath's picture

BTW ....... All the above are less expensive than the $43,000 Kalista DreamPlay, which rolls-off -5 db at 20 KHz :-) ........

Graham Luke's picture

blind tests are to audiophiles what crucifixes are to vampires.

Graham Luke's picture

...but maybe they have sold well in the Gulf States where they like their Rolls Royces gold-plated and their power absolute.

DH's picture

"rich sound that is close to the playback from a vinyl record on a turntable." As well as a standard setting, Vinyl Processor can be customized with adjustments for surface noise, tonearm resonance, and turntable resonance."

In other words, we designed an algorithm that recreates and adds in all the distortion produced by a typical TT during vinyl playback to your digital file, so that you can get that euphonic distortion you love. Hilarious.

Pity you didn't review this feature.

DH's picture

"With Roon performing the first or both unfoldings of MQA-encoded, 192kHz-sampled data, the Sony peculiarly displayed, respectively, "PCM 96kHz" or "PCM 48kHz."

Since when MQA encodes a 192k file it encodes only up to a 96k resolution (all material in the original above 48khz is discarded) this is not that peculiar. 192 MQA files are at best 96k files that are upsampled in the renderer to 192.

Bogolu Haranath's picture

So, trade-in your $200k turn-table and buy this Sony DAP? ....... Seems like a good deal :-) .........

Bogolu Haranath's picture

BTW ...... Can this Sony DAP make MQA files sound like vinyl play back? ....... That would be a major advancement in audio play back :-) .........

otaku's picture

I find it disappointing that an eight thousand dollar device cannot read an SD card that any cheapo cellphone or camera would be able to use.

ednazarko's picture

Glad that I'm not the only person who's had micro SD card compatibility issues. Every single player I've owned has been fussy about cards - and each had cards it preferred. Price of card or player isn't predictive, either. It's not cheap versus fancy cards or players - it has almost always come down to brand matching. Annoying.

I'm interested in the Sony's user interface, and how easy it is to find what you want to listen to if you've got 500GB of music loaded. I now only listen from computers, or iPhone, iPad or iPod, and have dumped most of my music players. Every one of them had a miserable UI and navigation experience, bad enough that I found myself never loading more than 100GB of music more or less (often less)... and then I'd still get frustrated trying to browse to find what I wanted to listen to.

I still have one player that plays high res files really well, and is very small. The UI ain't great, nor are the buttons and touch screens easy to work with. My solution - I've taken the 32GB and 64GB micro SD cards that accumulated over time, and loaded each card with a single playlist. The player and dozen cards travel with me in a coin purse. I pick the playlist that fits the mood, insert the card, and I can ignore the awful UI other than volume, and skipping cuts.

jeffhenning's picture

Given its size and weight, I'm somewhat perplexed as to where this fits into a person's music listening life.

I guess, most likely, your second or third condo where you enjoy laying in your bed listening to headphones?

It looks more fantastic than most Sony products and its performance is not in the least bit shabby, but I'm curious as to where they thought their buying audience for this was.

Unless, of course, this is a buyable prototype product. Companies of this size do make them so that they can then take that experience to scale them down... to people who don't own several condos.

Is it cool? Yes. Would you buy one to put it in concert with your main system or any system with an amp & speakers? I can't imagine why.

This is a lot of scratch for a media player for headphone listening. I'd have thought that they'd have added some regular line outs. Would that have raised the price marginally to $9K?

The box, though, is very pretty.

Robin Landseadel's picture

Agreed. My wish list for home digital player includes a lot of features this box box possesses, but for that kind of money:

1: It's not a "Walkman" and it's silly to call it one. A Walkman fits in a pocket, this doesn't

2: As a digital music server it should also function as a preamp, have regular RCA outs in addition to those headphone outs.

3: As a digital music server it should stream off the internet.

4: While we're at it, how about some analog inputs?

There's plenty of DAPs out there that are more flexible than this, cheaper than this, and they can fit in a pocket, like a "Walkman" is supposed to. I like the idea of a non-portable digital player that runs off batteries. My experience is that digital audio wants pure DC, a proper battery-based power supply for this sort of device makes sense. But for this kind of money, this item lacks flexibility.

Anton's picture

I kind of agree with everyone.

I saw a 1 TB small SSD for 40 bucks at Amazon.

If these babies could allow working slots for a dozen of those, imagine the joy!

I hope some of the players in the digital player industry hire a consumer or three and ask what they'd like to get done!

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