Review: Douk U4 (aka PJ Miaolai A4), Part II
From ELO: The Encounter of Douk U4, a Rollercoaster Story: Regret, Love, Hate and Redemption
A small hiccup to start. No sound with the stock 6N3. Several tries and I took a pic for DJ, who pointed out that the tube had lost its vacuum (oxidized white stuff) and that I had probably used too much force inserting the tube. I bought from TB a JAN GE 5670; it arrived soon and the unit worked fine. Everything below is with the 5670 tube.
When I first tried the U4 connected directly to my Aiyima A08 Pro, the latency was so severe it was not at all listenable. However, it was perfectly normal when my TV was connected to U4 through BT and sound had improved from using the Aiyima A08 Pro alone by a margin that was worth the implementation. Bass was taut and overall sound was more transparent.
Since my setup is 90% serving music streamed through Tidal, at this point U4 had seemed like a chicken bone - I could have it or not have it and it wouldn't affect me too much.
Conundrum While U4 flourished in my analog playback through Sound Burger (see below), I was still finding a lot of problems with my BT Tidal Streaming.
I tried to play Tidal through BT from my Tablet and the latency was so bad it was absolutely unbearable! The next morning, I tried it with my laptop as well as my mobile phone and the results were the same. DJ figured this might be because of the poor wifi signal at home, but then I tested my laptop and it clocked in at 690MB/s in downloading which is totally respectable! Then I turned off the wifi of my mobile phone and used pure 5G data to receive music signal and again, latency still persisted, so it's not the issue of poor wifi signal from my router.
After a long debug process, all I could suspect was that the Bluetooth version of my laptop, phone and tablet were not compatible with U4 (Shawn P has also some problem with his U4, shoosh; see below)...Perhaps I need an older version of phones to try it out again later. But even with the latency, I could still notice that the sound quality behind the stuttering was actually very decent! So I was not giving it up yet!
Tide Turning As the Sound Burger did connect via BT with the U4 and indeed flourished with the full metal jacket lineup of U4, E6 and UMI Duo (here), that rekindled my hope in U4.
The next morning, I was all gun-ho for a big session. I immediately started playing some familiar songs on the WEA. They were as good as usual, the way it should be. After a few songs to get my feet warmed up, I began to switch over to U4 with USB cable connected to my Laptop. Here are my observations:
This U4 is a rhythm machine with a highly engaging sound. There was not a bit of harshness and it had very good microdynamics and detail retrieval, especially when it comes to tracing the changes, the ebb and flow, the attack, dynamic and speed changes of violin, which is extremely difficult to reproduce. U4 seems to effortlessly achieve this, with flying colours.
Bass is good; while not the hefty, authentic type, you will not feel it lacking. Treble may not be as airy as WEA but again not lacking. But it is its musicality and ability to engage the listener that is quite rare in nowadays hifi equipment. Midrange is U4's game: smooth, slick, yet not sluggish, muddy or slow. I felt I did pick up addition details like fingering technique changes in guitar playback! No mean feat!
BT Restored! Previously, with BT my laptop had experienced terrible latency and sound was unlistenable. I didn't believe in fate and gave it another try on this morning. Surprise surprise! There was not even one bit of latency detected!!! I could then play and change songs remotely instead of running back and forth from my couch! Perhaps, this is the biggest driving force behind in retrying the bluetooth! My CEO was happy that at least got some exercise with all this song changing process. But not anymore now LOL! I have reverted back to a couch potato again.
The BT sound is very respectable with the TB Antenna which DJ helped me source. Highs are a bit screechy but the much needed treble energy of violin playback is there intact. Compared to USB, it is also richer in body and tone, but at the expense of trading off slightly (without affecting the enjoyment) clarity and the addictive foot tapping element (still has it though). Overall sound is very respectable, a trade off of hifi aspects in return for being able to remotely control the songs is more than welcome!
Can't be more happy since I have two sets of system both working nicely.
Douk U4 vs Wattson Emerson Analog For various reasons, I wasn't sure entirely whether this is a paragraph that I should write. WEA is such a great little device and I think it can compete against equipment costing many times more. WEA is like a foundation of my setup, which is now being shaken by this little U4...
With the U4, it is even more shocking to me since it can legitimately give my WEA run for the money! I think WEA sounds more hifi with better attenuation on high, more authoritative bass too. WEA does have more clarity and instrument separation and air. U4 came in with PRAT maxed out, more smoothness, and even more emotionally involving, less digital harshness whatsoever!
One other thing that U4 can do over WEA is that now I can play Youtube through U4 USB connection to the highest format !!!
Verdict There is no clear winner and both hold their own forte well and firmly. I prefer U4 in some ways and WEA in others. U4 is definitely a giant killer of another giant killer in WEA! That's no small feat to me. Given the progression from my lukewarm impression in the beginning to today's experience! That is so polarized! Kudos to U4 and I have completely transformed from a doubter to a total believer in a most dramatic way! I think this should be credited to my curiosity and inquisitive nature. At one moment I was ready to hand it back to DJ!! LOL
Latest update
After replacing the power supply of my modem to a DIY LPS and a Sommer LAN cable, my latest preference is still WEA for streaming Tidal. But now playing YouTube music through U4 is so frigging fantastic and so is sound coming out from playing vinyl via Sound Burger through U4!
Dilemma The dilemma has arisen...which setup shall I play every morning??! Until then, this is ELO signing off! Before that, go quickly grab a Douk U4 or PJ.Miaolai A4 ! Both are almost identical.
Nevertheless, immediately before my encounter with this RMB200 (less than US$30) unit; we were listening to a system which was worth multi-million Hong Kong dollars and it shows you how diversified doctorjohn is.
The Douk U4 between the two parts of the Kinnie Bluetooth Player. As you can see, the very thin Antenna Wire (said to be culled from WE equipment) is connected to the U4. Bluetooth used with RCA Out. Also see one of the pics below for the mysterious Terminal Box of the Kinnie Antenna SMA connector.
I heard plenty about the U4 from doctorjohn but honestly I was not interested mainly because I had the ifi ZEN Blue BT receiver and was not too keen on buying another BT unit. To echo what doctorjohn mentioned, I heard the U4 for the first time with a pretty good set up (here), an 845 self-built amp in a very nice venue (Thank you 生哥). The BT sounded ok with the stock antenna but it sounded a lot nicer with the Kinnie special antenna (same ink). The first encounter with the U4 was short but at least the sound was enjoyable; still, not interested enough to buy one.
Well then what made me purchase one? Doctorjohn subsequently mentioned U4 multiple times and I thought this little guy must have gotten something right. One evening, doctorjohn told me he purchased the PJ Miaolai A4 at an even lower price. The price was certainly one that “cannot go wrong” and I pulled the trigger.
A4 arrived and my initial system consisted of a stock A4, phone (using USB Audio Player Pro), MX500 look-alike headphones (less than CNY20 and not bad). That’s right, only headphones this time, I did not hook this up with my amp and speakers.
Initial test, random music from Tidal through BT but wait; no matter what I did, my phone would only use SBC codec but the Taobao page stated that the unit was aptX HD compatible. I messaged the seller and the seller confirmed that this is a “new” version which no longer uses aptX HD and I echo with doctorjohn again that the U4/A4 specs keep changing and it is like a box of chocolates, you never know what you're gonna get (sort of).
How did the SBC codec sound? Not bad, at least I did not dislike it. aptX HD, LDAC alike aren’t guarantee for good BT sound. I do not like how my Xiaomi 13T BT sounds and it uses LDAC. That said, I believe the SBC codec is limiting how good the U4 could sound and certainly would not do any justice to the A4.
For USB testing I used the trusted USB Audio Player Pro which sends bit-perfect files to the dac and since Tidal upgraded its monthly plan; all hi-res files are now available to me but that became a problem.
As mentioned by doctorjohn the A4 uses PCM2704 which takes up to 48kHz, 16-bit files, many of the bit-perfect hi-res files were not playable. The main issue was the sampling rate, anything higher than 48kHz would not be exported to U4, higher bit rates were ok as the beauty of binary is that you can simply disregard the last 6 bits from a 24-bit file to make it 16-bit. Easy!
Well, I did not have this issue before the Tidal plan upgrade as Tidal would simply convert all hi-res to 44.1kHz and 16-bit files but now Tidal does not do it. Oh well, I just stay with something with 48kHz or less sampling rates.
Enough of the old DAC issue, so how did it sound with USB? Not bad but I did not like how the highs sounded which sounded rough and a bit irritating. But I must say A4 can be used as a stand alone headphone amp and it has enough juice to get really loud. It is definitely much better than many USB dongle DACs, even better than some very expensive ones.
I listened to A4 with the stock tube for a couple of days so I would know for sure if tube rolling would affect the A4 and the first (and only so far) tube I rolled was the GE JAN5670W and what a difference the 5670 made! It completely transformed the A4 and most of the irritating highs were gone, the A4 sounded more musical.
However, I am a bit confused as to what the tube is doing in the circuit. I noticed the tube did get relatively warm/hot which was an indication that the filament was getting enough juice but when I tapped on the tube, I could not hear anything even though 5670 is notorious for being microphonic. What confuses me even more is that tube-rolling did affect U4 significantly.
Oh well, if it sounds good, I don't really care. I do recommend the U4.
Editor: Our writers are both esteemed professionals in their respective sectors, who write for interest. Unlike me, they are very busy people and I thank them for their time (no compensation to boot). As to what's presented here, if that's not investigative journalism, I don't know what is! In comparison, aesthetically and in practice, I had an easier time in Part I. Even more than I, they left no stone unturned. There is nowhere else where you will find this kind of obsessive working out of a piece of "cheap" gear from a user's ergonomic angle (we are not technocrats). We don't give up easily. Never Say Die (especially with "temperamental" gems like Douk U4 and E6) is a crucial factor in obtaining good sound.
ELO's heart-felt comparison of U4(A4) and WEA was indeed heart-wrenching and heart-warming! Kudos! Absolute Sound Treatment (mind you, I could only deliver that with my ears but not with my Streaming equipment, as I just stream casually)! And Shawn P's obsession with Streaming parameters also revealed unique and highly useful information. U can take that whatever U4(A4) you buy will be like his, SBC, no AptXD whatever. I myself am just a casual Streaming fellow, but I'm impressed by his App USB Audio Pro, which is very cheap and useful. It tells you everything about the file you're listening to! Investigate! While we here do not believe the more hi-res the better (too many factors in the digital chain) and indeed probably believe (at least me and icefox etc) the most primitive BT chips (like Chinese ones) with minimal function sound better than higher-spec'ed ones with extraneous and noise inducing peripheries, we are always willing to combine listening with data (unlike garbage "audio science" sites who know not at all how to listen). The U4(A4) is the best example of sonic performance (if not instant connectivity) that flies hard in the face of numbers and "science". Another proof is the well reviewed iFi Zen (Qualcomm), which Shawn P has and which ELO ditched in favor of a lowly Chinese one (here is the fascinating article).
Me? As BT had not always been a major portal of listening I have only had cheap Chinese BT. They are ALL good! But the tube-equipped U4(A4) is a cut above. It's now almost in exclusive use for me in China. In fact, I love it so much that I bought a similar AMP, the PJ Miaolai A7 which I shall write about soon. And I'm listening to BT more...
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