After copying the necessary test tones to its internal memory, I measured the Astell&Kern A&ultima SP1000 with my Audio Precision SYS2722 system (see the January 2008 "As We See It"). I couldn't obtain a 2.5mm balanced connector, so all measurements were taken from the single-ended 3.5mm headphone jack, with the volume control set to its maximum of "150" unless otherwise noted. (The volume control appears to operate in 0.5dB steps.) The SP1000 was running the 1.01CM firmware when I performed the measurements. (As I was packing up the unit to ship to our cover photographer, it updated its firmware to v.1.04 via my WiFi network.)
The A&ultima SP1000 preserved absolute polarity (ie, was non-inverting), and its output impedance, including 6' of interconnect, was both very low and close to the specification at 1.4 ohms from 20Hz to 20kHz. The maximum 20kz. maximum output level was 2.23V with data sampled at 44.1kHz. But to my surprise, when I measured the output level with 384kHz PCM data and DSD data, the output was clipped—it hadn't been clipped at the lower sample rate. I reduced the volume to "145," where the sinewave was no longer clipped, and examined the output level at all sample rates. It was 0.05dB lower at 88.2 and 96kHz than at 44.1 and 48kHz, and 0.2dB lower at 176.4 and 192kHz, but 2.3dB higher with 384kHz, DSD64, and DSD128 data (footnote 1). A puzzle.
Fig.1 shows the SP1000's impulse response with 44.1kHz data. It reveals the reconstruction filter to be a minimum-phase type, with all ringing following the single sample at 0dBFS. With 44.1kHz-sampled white noise at –4dBFS (fig.2, red and magenta traces), the player's output rolled off above 20kHz, reaching its stopband level above 24kHz. (The vertical green line in this graph indicates the Nyquist frequency, which is half the sample rate of 44.1kHz.) With a full-scale tone at 19.1kHz (blue and cyan traces), the aliased image of the tone at 25kHz is suppressed by more than 100dB, and the distortion harmonics are all very low in level.
Fig.3 shows the A&ultima's frequency response at sample rates of 44.1, 96, 192, and 384kHz, with the level at the last rate adjusted for the level difference noted earlier. The rolloffs at 44.1 and 192kHz are similar but different in shape from those at 96 and 384kHz, which are shallower. While performing these measurements, I noted something odd with 96kHz data. Unlike with the other sample rates, the trace on the screen of the oscilloscope I use to monitor a product's analog output was discontinuous, and very similar to what I've found with so-called NOS (Non-OverSampling) DACs. There must be a problem with the implementation of the reconstruction filter with 96kHz data.
Channel separation was superb, at >100dB in the midrange, though it did decrease at lower frequencies, presumably due to the rising power-supply impedance. But the A&ultima's noise floor was both free from spuriae and very low in level. With a dithered tone at –90dBFS, increasing the data's bit depth from 16 to 24 dropped the noise floor by more than 20dB (fig.4), implying resolution of at least 19 bits—superb behavior for a digital product that runs off a 5V battery! With undithered data representing a 1kHz tone at –90.31dBFS, the superb resolution and low level of analog noise allowed the waveform to be accurately reproduced (fig.5), with both the three DC voltages and the minimum-phase filter's ringing readily apparent. With undithered 24-bit data, the result was a clean sinewave (fig.6).
At maximum level into 100k ohms, the SP100 produced very low levels of harmonic distortion (fig.7), with the innocuous second harmonic the highest in level, at just –90dB (0.003%). But into lower impedances, the output started to clip with the volume control set to "150." Into 300 ohms, for example, which is typical of the impedance of Sennheiser headphones, the output clipped at "145." I doubt that this will be a problem at normal listening levels, even with low-impedance 'phones. Figs. 8 and 9 are wideband spectra respectively taken with a full-scale 1kHz tone with 24/44.1 and DSD128 data. The ultrasonic noise floor with PCM data is clean, while with DSD data, you can see the rise in the floor above 50kHz, due to the single-bit encoding. Intermodulation distortion was also very low, even into 300 ohms (fig.10).
When I tested for jitter with 16-bit and 24-bit/44.1kHz J-Test data (figs.11 & 12), all the odd-order harmonics of the LSB-level, low-frequency squarewave were at the correct level, other than the one just below the spectral spike that represents the high-level tone at 11.025kHz. Some spreading can be seen at the base of this spike, presumably due to low levels of low-frequency, random jitter, but a couple of spurious tones can be seen just above 8 and 12kHz. These are very low in level, however, respectively lying at –125 and –134dB, and I am confident they will not be audible.
Other than that anomalous behavior with 96kHz data, Astell&Kern's A&ultima SP1000 acquitted itself well on the test bench. And for it to offer such superb resolution with a low-voltage battery supply is commendable.—John Atkinson
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COMMENTS
At this price and quality some may buy this to use as a solution for at-home listening through ones home system as well as using it on the go. Perhaps this duel use could justify the price? Could it offer a better solution than a stand alone server/DAC and portable player for the same total budget?
I would use it as the core of a home system, except that I'd have to make sure it's not constantly charging the battery when plugged into the AC mains.
1. The machine looks heavy. Is that useful in a portable player?
2. At this price I would expect perfection. What is the issue with that clipping into 300 Ohm and behavior at 96hHz?
3. How does it compare to LG V30?
4. Are there any cheaper alternatives?
we needed 3 Devices to do what these AK players do.
The AK240 is pretty much the ultimate travel rig.
This new AK is better but I'm not clear as to why.
Still, the darn thing is cheap compared to anything in High-End and it doesn't have a Monthy Subscription Rate like an iPhone so it's Pay-Once sort of thing.
Well, how long is it's service life?, we should know that sort of thing, shouldn't we? Sony Walkman stuff lasts 4evvvvvvvah. Will these AK devices end up in the dead drawer with all those little electronic things we no longer use? or is there a 'deep' support system established and if so, where is it and just how do we access it?
What about those Batteries?, who replaces them when they won't take a charge?, that will affect ReSale Values and Trade-in Residuals, won't it?
There's lots of 'what about' questions that need answers when it comes to much of this Asian stuff, it starts to matter as prices increase beyond the cheap price of a eBay Chinese digital pedometers.
Sony had a Service Center here in Michigan that they closed a looooooong time ago. Now, if an Asian device needs service we end up looking for a local lad with our fingers crossed. Phew.
Expensive Asian Electronics is 'Risky Business'
So, the decision on a $3,500 Asian gizmo is a matter of Disposable Income: Can we afford to loose our investment?
Some Asian stuff has superb support: KIA, Samsung, Nikon, Cannon and quite a few others but not everything by a long shot.
Astel & Kern is the highest end of high end travel gear for music lovers. I think it could replace everyone's music source with the possible exception of a died-in-the-wool Vinyl guy or a guy like me that has an iMac as my Big Base System.
But, the Smart Phone is just around the Corner and coming fast. One Smart Phone already has a quad DAC. So, these beautiful Astel players seem to be on borrowed time.
Here comes iPhone 9
Tony in Michigan
ps. Quincy Jones showed me Electrocompaniet
True, MQA capable phones/portable DACs can soon move aside the storage and retrieval function of these players. However, arguably, the electric storm that is a phone will not be able to compete at the ultimate level with dedicated players. Possibly irrelevant when travel and flight noises are a nuisance.
I more than 'mostly' agree with you.
These AK players are much greater than 'this' review experience reveals.
Overall, I'd say, this Analog Planet guy has just given ( his loyal following ) permission to buy, own and enjoy this cute little $3,500 digital player. hmm It's a 3rd. Generation music format device.
Which seems to be the point behind this interesting personal story : 'Analog Planet' is recommending Digital Players now. Who could've predicted this outcome?, of course, it's a toy compared to anything Analog, where prices for serious gear begin at twice the measly price of the AK.
Anyone that can find happiness with an AK player should consider themselves lucky not be burdened with having to manage a vault filled with pristine vinyl, hundreds of thousands of dollars in playback gear and the general disapproval of family members who probably consider the vinyl guy a 'crazy' uncle sort of person. ( which might or might not be the case ).
The 4th. Generation Format is where we play our music on our Smart Phone and we Rent our music from Tidal or some other outfit.
What the 5th Generation will look like will be fun guesswork for the next 25 years.
Tony in Michigan
ps. I've lived in all 4 Generations of music formats and I'm pleased with this 3rd. Generation and it's playback gear. The full implementation of the 4th Generation Format seems too good to be true.
"The 4th. Generation Format is where we play our music on our Smart Phone and we Rent our music from Tidal or some other outfit."
They've been saying that about the Cloud (or whatever they call the latest "we provide the best uptime" service) since before the Internet, when IT services were provided by Big Blue and others. There will never be a streaming service so reliable that I can depend on it 100 percent, during the critical 90 minutes I have between missions where I can listen to my favorite symphony uninterrupted.
it's still the 4th.
I hope they make it reliable and universally useful.
We'll still have old geezers like me collecting the hell out of CDs and loving the playback on the latest Oppo.
I hope the 4th becomes a smashing success for all involved, I'd love to have unlimited access to all the music ever recorded.
preferably for free or less with a lifetime subscription to room and Tidal.
Tony in Michigan
Old geezers like me will have a 5-10 terabyte Sandisk flash drive, size 2x2x0.5 inches in my wallet, with tens of thousands of music and video tracks at my fingertips for instant lookup and playback.
I have hundreds of tracks that will likely never be on the streaming services, or if any of them are, they'll be nearly impossible to find (read: time consuming).
When you really think about all of the show-stoppers between you and some specific but not easily accessible tracks you want to hear, you'll be saying "Well, I didn't need to hear that anyway - lots of other things to listen to."
And it's not that you *have* to hear what you want, nor is it that other good things aren't available - the simple fact is that there are consequences to giving up control of your music, and you should be honest and acknowledge those consequences.
Sure, 5-10 terabytes.
I have all my music on memory.
But, there's plenty of interesting music out there to explore.
Still, I don't know how much time i have left, I'm having another Ct Scan Nov 7th. I could get bad news at any time.
On Sony: I had a few un-repared SONY ProVideo pieces. I was mostly referring to Garage Sale Walkman stuff. Of course everything, even Motorola & vintage Western Electric stuff can and does break, nothing is immune to failures. ( except the loyalty of Trumpeters )
Tony in Michigan
I hope your scan goes OK - I've had so many scans that they killed all the bugs in my system. I don't know how many Trumpeters you know, but I always played Cornet myself. And BTW, we've decided that the current administration will continue forever through inheritance, much like a good universal music format that doesn't need to be replaced. And that's the name of that tune.
Funny thing - I have several friends who thought the 'maga' thing was a scam - not needed. But then a few weeks later they're talking about our "empire in decline". Could be my friends fell into the quantum rabbit hole, and still think 2 plus 2 equals 3.
Please take some antacid and call your gastroenterologist in the morning. The review was not intended to give anyone "permission" to buy this player. It is not a "toy". No one considers me a "crazy" uncle sort of person. However you sound unhinged. There's no apostrophe in "its playback gear". Not sure who to whom the "we" refers in your post. "Crazy" people usually address imaginary people like that. I've used this player on airplanes, at the gym, at the pool etc. It's filled with 96/24 vinyl rips that sound better than any downloaded files or streamed on TIDAL files, though I appreciate TIDAL a great deal as a means to buy new vinyl.
"Unhinged" ?
You may be right, back then ( about one year ago ) I was undergoing a Second Cancer Screening to confirm. My older twin brother just died of Brain Tumors. So-far, I'm clear but have to keep a close watch for active killers.
I'm scared for the first time in my looooooong life. I might be acting out my fears.
Tony in Michigan
"Sony Walkman stuff lasts 4evvvvvvvah."
Well, no. I had a couple of Sony WMD6C's that were practically indestructable, and a couple of reliable Sony TVs in the 1970's. Of the thirty other Sony handheld products I've had, all failed within 3 months. The VAIO computer ($2500) was a joke - the only service center available to me (I was in Irvine CA) was a fly-by-night outfit in Florida, which put the wrong O/S on it, then after 6 weeks when they returned it, it failed permanently.
Not to mention the handheld digital recorder ($800) I bought circa 1992, which used Sony camcorder batteries as I remember. Both the original battery and a genuine Sony backup battery I bought ($110 each) failed after about 3 charges.
well then, phew.
Garage sales have Sony stuff, it always seems to work.
buuuuuuuut,
I'll accept that my experiences are different.
Tony in Michigan
It's arguable that your experiences in product failure are different, but if you had the defective Vaio in So. California, your experience with Sony service would NOT have been different.
As I'm sure I said already, my Sony handheld products had a more than 90 percent failure rate within the first 3 months. The only reliable Walkmans I found were the D6C's. The *primary* gripe I had against the tiny computer wasn't the failure anyway, it was the scam "service". The other failures I either returned or tossed.
“You were expecting something else?” Yeah, I was. I was hoping that the respected Mikey would respect himself and those of us who have spent time to also learn the portable format with a professional review of the standard of his analogue corner.
Zero absolute experience? Check. No relative benchmarks? Check. New associated equipment? Check. Focus on headphones instead of the player? Check.
An Iphone user phoning in his review. Then again, I did learn that a larger, heavier object balances better on the airplane table during turbulence. Duh.
Mikey you are literally the last reviewer that I read. Please don't take that away from me!
Now on the players:
(1) In the same way that the AK240 was bested by the 380, this new player is a further step towards the AK evolution and house sound.
(2) It is significantly more powerful and the control of headphones is greater, solid and noticeable.
(3) There is an increase in soundstage, especially horizontally.
(4) The player continues to not be the quietest thing around (the Sony beats it handily there) but it is more "airy" and as such still quite engaging.
Richardharmer: you would need to be specific about which comparison you seek. I can say that for headphones, paired with a good amp, it can be the base of a very high end system. Otherwise I dont know.
mrkaic: it is heavy like the Sony. Both companies will claim that is necessary for isolation and sound quality. They both feel great. I wouldn't want either in my pocket unless it is a jacket. But you can survive an hour at the airport before sitting down on the plane. Compared to the LG? It blows it out of the water. These are not comparable devices. Yes there are tons of alternatives from AK, Sony, Fiio, iBasso, HiFiMan, Onkyo, Pioneer, Questyle, Pono, etc. Some would in fact argue that buying a less expensive player and pairing it with a great portable amp like Vorzuge's offerings (or Chord etc) may be a better overall idea for performance.
tonykaz: I respectfully disagree. The Sony gold is indeed regarded as the best player (as can be seen by its dominance of shows lately) but obviously one can very reasonably argue against that (what is "best" anyway.) I am a lot less worried about reliability as the quality of these devices has proven to be excellent. Whether AK survives as a brand is another issue/question. But for those starting up, I would look for used equipment where the initial 30% discount is already gone.
I'll stop reviewing portable players. I had to start somewhere. You've given me the incentive to stop. I don't need to take shit from anyone at this point in my reviewing career so I will not explore this subject any further.
Hi Michael...I have been following your online videos, reviews, comments etc for a couple of years now. I am a planetary scientist with some expertise in a number of areas, but I can safely say that the #1 expertise I have acquired over time is to know when a person might know a thing or two more than I do about a subject and maybe listen and learn. After reading all the comments above, I felt compelled to join the site and ask that you continue to review "outside the box" (not just digital players!). I think it's great you that you happened by a product that you didn't expect to review, but tried it, found it worthwhile, and related the experience to the rest of us. Anyone who follows your reviews know that you are not afraid to say if a thing is shite or not, and that you are always very careful to give qualifiers and caveats where needed when expressing a subjective opinion (which you assume full responsibilty for). In the final analysis, opinions aside, I have always found your reviews to be informative and insightful based on your experience, which is why I continue to follow your reviews! That you expect us to not be rude in considering your learned and experienced opinion is hardly a lot to ask. I am sure I speak for a lot of readers when I say that the enjoyment of my audiophile hobby has only been enriched by your reviews over time. Of course, "Analog Planet" is mainly about all things analogue, but it's always refreshing when you aren't "prescriptionist" and venture "outside the box" in giving us useful and insightful comparisons of the analogue and digital worlds where appropriate. With candor I can also say that for my part, I really enjoy the slight irreverence and cheekiness that is part of your cache. And your insistence that folks employ a modicum of common sense and critical reasoning in following your reviews. Many thanks and I hope your reconsider your position regarding reviewing "outside the box". After all, that is usually where all the interesting stuff and fun is!
Best regards,
Chris Parkinson
3500 Euros and portable ? No, thank you. I am happy with my opus 2, which is not the cheapest DAP too, but I would never invest more into a portable player
I got a refurb SanDisc portable for $30 and listen to it via a Grado SR60. And I'll bet dollars to donuts that you can't hear a difference. Prove me wrong ... and tell my why.
Plus, it firmly clips onto my clothing ... which your $3500 player is incapable of doing.
And a Sony portable CD player if I don't want to do any transferring. Not perfection, but it's good enough, y'know?
This 3000 dollar plus A&K can't do anything that a cheap Android phone, the 10 dollar Onkyo HD player app, a plug in micro or nano memory card, (for which most Android phones now have one or two slots), and a Chord Mojo can't do at an equal or possibly better quality, lower weight, and no bigger (even though it is 'two box').
And you can make phone call on that too :)
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