Nobsound E6 Part I Douk Direct Heated Triode Preamp

Click pics to enlarge. From L: Reisong 1:1 Transformer; E6 (note the rear power supply plug is in 2 segments, 5*52.1 supply cord with adaptor to required 5.5*2.5); ETA Preamp; 6J4/6P3P Preamp.

Review: Nobsound (Douk) E6 Direct-Heated (Triode) Preamp, Part I
Letter from Shenzhen (23-10): Antagonistic or Complementary? vs Eastern Transmission Audio 6N3 Preamp

Part II, which details the Capacitor Mod, and feedback from my NYC friends, had been published.

Part III, which tells of Phase Reversal and more ways to combat Microphonics, also published.

Editor: 1) As detailed below, the Review Unit was a loaner; 2) Just before writing this article, I was able to confirm a few technical aspects from the company; 3) Before writing this article, I read the Amazon comments and there are misconceptions there that should be corrected.

How It Came About Not so long ago, I was on wechat with our own HK Author Shawn P, and he mentioned his interest in the Nobsound (Douk) E6. It just happened that I have also noticed this for a long time. It‘s a tiny preamp that nonetheless employs a Direct-Heated tube (DH)!!!! As a long-time purveyor of DH Triodes, of course it came under my radar! Just like our other HK author ELO’s interest in Aiyima T9 spurred me on to my Aiyima adventures, I decided to pursue this one.

I first contacted the TB Nobsound (Douk) Customer Service. Despite some delays, the fellow eventually through wechat referred me to Vivian of Administration. The lady was nice (but cautious, for good reason), and meticulously verified me as owner of this Blog. After a while, I was loaned the E6 for Review. Although I didn’t buy it through Taobao, I’m still providing the details for you.

https://m.tb.cn/h.UrSBNMH?tk=bKVCdQqfg4E

Shipping The package was a surprise. It came in a small plain cardboard box, no logo whatsoever. The unit had the tubes installed and bubble-wrapped, with a USB cable on top and not much else. I’d imagine it could suffer damage in some circumstances.

Ergonomics There’s not much to it. It’s not much bigger than a deck of cards. The back has only the Single RCA Input and DC Input. The RCA Output is at the front, together with the Volume Knob/On-Off Switch. Having the Output at the Front is a Form Factor that takes some getting used to for most audiophiles. No 5V Power Supply included (everyone has some USB chargers). At Turn On, there is no sound until the Relay clicks a few short seconds later. For those who use solid state amps I’d wait a little longer (say, 1 minute, for safety against DC offset, in general) before turning on the amp. Ah, it’s too bad its face and rear plates are in gold - I wish a black or grey version option is available. I ain’t no fan of gold, like the Jadis and Sonic Frontiers that sell to Asian markets.

Specifications and Technical Aspects
This VERY unusual Preamp employs an obscure 2J27 DH Pentode (stock is Chinese). Wow! Direct-Heated! IT TURNED OUT THE E6 IS CONNECTED AS A TRIODE! ALL of the DH Preamps that I know of are Triodes and quite expensive. My own Manley 300B is an example (much cheaper would be the interesting Transcendent 300B Preamp Kit). And, in the recent Shenzhen Audio Show I heard the excellent Line Magnetic Foshan 安歌 2A3 Preamp (around RMB 20k), and it was great! If I were to start over serious, that would be on the top of my list! I enthusiastically applaud Douk for designing this Preamp out of the blue! At this bargain price, people don’t know the efforts that went into it. DH tube and low filament voltage mean high variability and susceptibility to Microphonics, as you shall see.

The Unit employs a 5V DC power supply, and only comes with an USB to DC Plug (5.5*2.5; the most common type) that even the manual suggest you to use with your USB charger (one that delivers above 0.34A). That’s not what I used of course! I used my Wanptek SMPS. The display shows a constant draw of 0.4 mA, no more. As some 2.5 sockets will accept 2.1 (standard for DC power supply plug) I tried without the adaptor - no go. So you need to make sure it’s 5.5*2.5 (with an adaptor in my case).

The 5V DC Power Supply goes through a switching supply to up it to 105V Rail for the HV B+. This is common in digital amps (usually 12V). In my own experience there is precedence in the ancient (and excellent sounding) Japanese Elekit TU-875 Preamp (which our ELO uses right now), which employs a 7V DC Input, which then is internally raised to higher B+. Fascinating (Douk told me it’s not easy to implement because of the very low filament voltage).

I was told by Douk that the Amplification is ALL tube (and it sounds as such, see below). As you can see from the pics at the bottom, crowded around the tube sockets are Surface Mount Components (SMC) of resistors and capacitors, which offer no route for upgrade (neither are there cables inside). But, fortunately, the 4 Grey Coffin Capacitors turn out to be for Input and Output Coupling. They are unusually high in Value, at 1.0uF 250V. This is great news for those of us who want to modify! Warning: very little room inside! Most big boutique caps would NOT fit!

Shock Absorption and Microphonics At first, I was greeted with the ringing sound of Microphonics, which died down after some seconds. The unit is very sensitive to impact. Because of its tiny size and lightweight, it can easily get knocked around even if you just want to change the volume. I put it on a solid slab of rubber shock absorber (now is different from the 2 cubes used in the top pic. Once the unit stabilizes after turn-on, there is no microphonics. This is due to lack of reinforcement in the internal tube structure. Some Amazon users though had continuous high-pitched sound, which may be a different matter, like a faulty tube. Ringing upon some form of shaking is normal for the Chinese tube. I would advise against using this on the desktop where you work, especially if your loudspeakers are also on the tabletop. Your moves (and those of your loudspeakers) may shake the table and cause trouble. Now, why bother, you may ask? Because of the Sound, of course! Also, before you move on to below, in the tube rolling section I have a very useful surprise, so make sure you read it!

Sound This is a surprise, to say the least. I’m not the only one who harbors the opinion that the larger the tube (and structure), the better the sound (hence 6SN7 > 6CG7 > 12AU7; for some too Globe > ST > GT, thought I have my reservations about that). With its big envelope (like a 6SN7 in size but housing only one triode) and large structures (the plate is about 2/3 the size of the output tubes 6V6 and EL84) I expected a bigger and sweeter sound, but I was still floored! Prior to receiving this, I have been using the modified Eastern Transmission Audio (ETA) 6N3 SRPP Preamp (Review and Mods), which is similarly priced and a formidable rival. Swapping in the Douk, the sound was instantly bolder and sweeter. Images were larger and fleshier, and so sweet that not a trace of digititis was to be had. Gain is still on the high side but not quite as much as the ETA. The amp is also very quiet, no background noise.

Does the E6 trump the ETA? It gets fascinating. A quick answer is - No. With stock tubes, great as it is, compared to the ETA, the E6 does have its weaknesses. The first is its Control, which, though not bad, does become less firm in classical big moments. The second is its Dynamic Shadings are less sophisticated. Also, the E6 is more saturated in color, but this is likely a plus rather than a minus for most people. Or, put it another way, the ETA has superior neutrality, control, microdynamics and details (or integration of the latter two). On the other hand, the Enhanced Presence of the E6 is amply evident - it puts the soloist forward and is very emotive, not something that a cheap (or even very expensive) preamp can do! 

For musical examples of ETA vs E6, in my recent Classical Streaming article I actually provided some, duplicated in the shaded box below ((if you want to read it in context, just roll down, or click here):

Either/Or: 2 Preamps
Recently, I was loaned a Nobsound (Douk) E6 Preamp, which uses the unusual 2J27S Direct Heated Tube. The chassis is very small and the tubes sticking out are big (almost size of a shorter vintage 6SN7) but the sound is big. Review to come. Before this, I have been using the modified Eastern Transmission Audio (ETA). In a nutshell, the diminutive Nobsound/Douk has a bigger, bolder sound, bigger images, but less control. The ETA has somewhat smaller images but greater depth and better dynamic gradations.

I stream mostly on NML, which has a leaner sound sometimes. I also do Tidal, which seems fuller, but colored. With some recordings, neither seem perfect. Sometimes switching from one preamp to the other brings improvement, even change of view of the performance. Let me just cite 2 examples using albums covered above.

When I streamed the Van Kuijk recordings with the ETA, I frequently feel the sound to be a little on the white side. This is a consistent observation of the Alpha label. When I switched to the E6, the strings instantly became just a little fuller sounding. Just what it needs. On the other hand, when I streamed the Schubert Trios with the E6, things are just not as woven as I’d like. Switching to the ETA firms up the piano and knit things together.

You get the gist. Which one is more accurate? I don’t look at it that way. Truth, whether in audio or politics, has many facets. In audio, unlike in reality, we can search for truth as long as we want. Nothing is forced down our throats.

Click pic to enlarge. Note the Outer Perimeter of the Sleeve is folded inward on the top plate.

Tube Rolling There is not much choice. Aside from the stock Chinese tubes, there is only the progenitor Russian version of 2J27, or in transliterated Chinese notation 2米27, which is how it’s designated on TB (link below). And so I bought 2 from this fellow in Hebei. Cheap. Western readers shall find plenty (and cheap) on Ebay, most shipped from Ukraine, where else!

https://m.tb.cn/h.UJojzmO?tk=OiECdQq2gkb

Problem is, the Russian version is the original metal tube. They would not insert into the E6 as the diameter is just a little bigger than the holes. This is really silly - I guess Douk thinks the tube looks much better in glass form (it does) but to us old geeks, plugging in the metal tubes would make the E6 look like a Step Up Transformer (SUT), no problem. BUT, SO, you need to take off the outer armor. Douk takes them off the Chinese ones but they don’t offer the Russian (yet), so you have to DIY. In the pics at the bottom, I’ve provided what I hope are enough guidance. If you plan to do it, you MUST read everything carefully, particularly pin orientation.

There is little question that (as usual) the Russian version is superior. While just as bold and sweet, it firms up the mix and is more dynamically nuanced. It makes the E6 a more rounded preamp even in comparison with the ETA. It now wears its own attributes proudly, and there is no serious downside.

AND, importantly, a side-benefit! The Russian tubes also more sturdy, and certainly much less microphonic. Yes, a sudden jolt (or tap on the chassis) can still induce some ringing, but they are much shorter in duration and muted.

Conclusions

• Sonically, the E6 is a miraculous product for those who can use it. It offers a glimpse into the world of DHT output tube, at crazy low cost. It’s basically unique. Being a budget product (albeit one designed with love), it has limitations, but it’s a window into another world, far away from the usual humdrum of low-end products (so is the ETA, more conventional in design but good sounding). In fact, if you get both the ETA and E6, you shall have a good glimpse into the world of Preamps - they are like Yin and Yang in a way, challenging but supporting each other rather than having you say A is better than B, and B is better than C...ad nauseum. No better musical (audio) education at this price. These two should provide a reality testing for much pricier rivals. 

• Even after Tube Change, the differences remain: the E6 is "artistic", with great Presence, and paints in broader, "Live" strokes; the ETA is a more meticulous craftsman who arranges things in order, and minds every little detail.

• If you cannot provide better isolation for the E6, DON’T get it. If you use it on your desktop or have your loudspeakers on the desktop, and you type and vibrate the desk (not to mention when you pump your fist in frustration), it’s not for you.

• The Russian 2J27 is a definite PLUS for sonic as well as microphonic reasons. Order a couple more in case you mess up removing the shell (not likely). Believe me, It’s worth your while.

I now alternate between my ETA and Nobsound. I LOVE both for their different strengths. Now, those caps of the E6...As usual, watch this space...Obviously, I intend to purchase the Review Specimen.

Removing the Outer Metal Sleeve

Before doing anything else, The FIRST thing you do is to look at the bottom. The Center Guide Pin (which is part of the metal sleeve) has a Protruding Ridge. You MUST use a MARKER

and mark the two pins to the right and left, because after the glass tube

slides out, there is no orientation. 

After the tube is taken out, the 2 pins in question should be clearly marked.

Anatomy of the Tube. The Metal (Tin-like and soft) is folded on the top metal disc, 

beneath which are many cardboard rings（Khaki color; you can see many out-focused in the background) to adapt to the dome top of the glass tube.

First, remove the top black screw.

I use a sharp-nosed Wire-Cutter for the job. Nibble at the edge and create a defect,

 cut horizontally and roll back the metal. There's a lot of clearance

between the top metal plate and the tube, so don't be afraid.

Streaming Classical Douk Nobsound E6

Streaming Classical (23-3): Finally, Good Performances of Russian Works are Trickling In
Letter from Shenzhen (23-9): Either/Or, Tale of Two Preamps

Updated 3/24/23: Minor editing, and some more info on Liss added.

Editor: The Sub-Heading refers to my listening experience using 2 preamps that complement each other. Sometimes when I find the sound of a recording not to my liking, I make sure I listen to it on the other preamp, which may save the day. This bit of audio experience I shall briefly detail more at the end of this article. First, the recordings.

In one of the Streaming Posts last year, I lamented the dislocation of Tugan Sokhiev, one of Russia’s (and the world's) pre-eminent conductors, who resigned as director from both his French post (Toulouse) AND the highly prestigious Bolshoi Theater, thus robbing us of a potentially highly competitive Shostakovich cycle (with the Toulouse Warner had already released No. 8 and 10).

Browsing prestomusic today, to my surprise I see an imminent release by the dissolved team; it’s due in April, them being accompanists for my heroine Elizabeth Leonskaja in Beethoven 3 and 4. Warner indicates this was from 2017-8 concerts. I’m looking forward to it but can’t help wondering if this is a way for Warner to partially fulfill their contractual obligations, which are surely in limbo. My view: Toulouse forced out Sokhiev, the best director they ever had, who over a decade raised their profile and brought them a priceless Warner recording contract that other orchestras as good or better than them (truth: many out there) would kill for; Toulouse should have the decency to release Warner of any obligations. It’ll take years for Toulouse to regain the footage they have lost - not likely. When Art gets used by Politics, the only losers are the Artists.

And so a potentially excellent Shostakovich cycle by Sokhiev was violently aborted. Instead, mediocre conductors like Giancarlo Noseda soldiers on with useless UK recordings (LSO Live; NSO Washington are equally bad; only praised by UK press;). Avoid his spineless Shosty cycle. This fellow has never produced any significant stuff, in any area, but the UK press always inexplicably praise him. Ditto LSO, which, despite their high individual skills, now make one impersonal and underwhelming recording after another. No personality. Ditto over-rated conductors, like Rattle, who goes on to water down other orchestras. Emperors without clothes.

Isn’t that hypocrisy? Banish all great Russian musicians in their own music? Instead have them performed by politically “correct” yet musically pallid Westerners that soften everything? That’s really cultural appropriation, if you ask me.

Russian conductors (and musicians) are unfairly shunned like the plague by decision-wielding me-too politicians and bureaucrats (a few brave Austrian official voices notwithstanding). Have you noticed that even Russian labels (like Mariinsky’s own) have few new issues? That’s a sad void. And so it’s an obligation to promote the few recordings that trickle in.

Dimitry Liss, who heads the phenomenal Urals Philharmonic, has received coverage here before. Now, he is giving us Shostakovich 10 (Fuga Libera), a work which is close to his heart. This was not the first time Liss has recorded this. Just compare this to the previous recording he did with his other orchestra, the Phil Zuidnederland, and you shall be impressed by the superiority of the Russians. Listeners who really know Shosty will know why he MUST be continuously performed by Russian musicians, no matter who’s in charge. And then there is the excellent and substantial release of two of Prokofiev’s best works, Symphony 2 and PC 2 (pianist Korobeinikov).

While we’re on Shosty, fortunately there ARE worthy UK efforts recently, from the team of BBC Phil and Storgards. Their newest release of 12 and 15 is refreshing (Chandos), no less because of the rarity of 12, which I somehow have always loved. The enigmatic 15 is of course a masterpiece. The team’s previous 11 was good too, and this one is promising as a cycle. Not exactly heart-on-sleeve, but meticulously crafted, paced and delivered (unlike the clueless Noseda). Very good sound.

Too many unworthy recordings, but all is not lost. Occasionally we have a GREAT one. Now, Stravinsky is not even considered all-Russian really, given his long exile and sojourn in the West. But he was. And NOTHING is more Russian than his masterpiece Les Noces (Russian Wedding). This is not an easy piece to listen to, especially as it is sung in Russian. If you note the genesis of the piece, it has a convoluted history. The version most often performed is the later 4-piano version, not Stravinsky’s first choice. And so I have listened to it as such, until I recently came across this stunning original 1919 version, which the composer has only partially finished (completed in 2007 by Theo Verby)! Featuring Cimbaloms and Pianolas, no less! The performance by Ensemble Aedes and Les Siecles under Mathieu Romano is beyond reproach (Aparte). As I streamed it on NML, I was able to read the fascinating booklet notes, where the vocal coach showed how she devised ways to teach the French choir how to enunciate Russian, and indeed they sound quite authentic! A labor of love! The filler is a curiosity, Bolero arranged for choir! Sound is stunning - this is goose pimple material! This is my Album of the Year! I don’t see anything coming close. The only caveat is certainly not every reader will find it comfortable listening, though I fail to see why someone who likes Le Sacre will not like this. And audiophiles should flock to this stunning recording (as they should to Berio; see below).

As I let the tremendous colors of the performance wash over me, I was reminded of some past moments of utter joy. One from long ago, when I first listened to Berio’s epoch-making Sinfonia. The raucousness, the jaw dropping thrills on a good system (in case you want to listen, there are many good recordings out there now, say, Chailly on Decca)!

The other association was not so apparent. I thought of Gergiev, now completely ostracized by the West. I recalled his magnificent concert performance of Prokofiev’s Love of Three Oranges with the Mariinsky in 2008 that I had the fortune of attending in NYC. I still remember it vividly, so authentic and thrilling! The Russian colors of this rarely performed (or staged) Prokofiev piece is as strong as Stravinsky’s.

My words then shall serve now equally well: "...The performance makes you really ponder the empty slogans used to promote many also-run conductors and orchestras...

There is a whole contigent out there worshipping mediocrity, giving standing ovations to undeserving performances. Sign of the times. Thankfully, we still have the Russians..."

Since we mentioned LSO before, here are my concert reviews of Gergiev that include his LSO visit in NYC in 2009. Believe me, the LSO don't play like that now with most conductors.

I also thought of him as I had just recently watched a (Tidal) older video album of him conducting Prokofiev Symphonies 1 and 5, and PC 1 with a very young Trifonov. It’s fabulous stuff, magnificently played by all. You can stick with your Noseda, I’ll follow my Russians.

Another surprise is Rafael Payare. I didn’t like a previous album of his (of all composers, Shostakovich) but I was surprised to see him conduct the Montreal Symphony Orchestra in Mahler 5 (on prestigious Pentatone no less). Doing some research I was surprised that this new name to me is now director of the MSO, an orchestra I have long loved. Well, the recording is superb, with coiled tension and great playing, and in great sound! I don’t know why M5 is so popular in concert programs - most conductors fail in live performances (like the flaccid BSO/Andris Nelson and Baltimore/Marin Alsop I heard at Carnegie some years ago).

For something more angular, I’m a fan of the music of Grazyna Bacewicz and have previously recommended her String Quartets (Silesian on Chandos) and Violin Concertos (Kurkowicz on Chandos). Her string music for orchestra are somewhat more astringent, but well worth listening to, as performed by the Primuz Chamber Orchestra (Dux).

Violin
The exceptional find for me is Maria Milstein, Moscow-born and Holland based. Her Prokofiev playing are now references for me. Both the Concertos, with the Phion Orchestra under Otto Tausk (Channel), and the Two Violin Sonatas album (which includes Prokofiev)(Challenge) with husband Mathieu van Bellen, are indispensable. Van Bellen is also violinist of the excellent Busch Trio. All together, they deliver an excellent Dvroak Piano Quintets album (Alpha). Maria Milstein and her pianist sister Nathalia also shine as duo in several excellent albums (Mirare). As if that’s not enough, Maria is also part of the Van Baerle Trio, which also includes a personal fav, pianist Hannes Minaar, and they do excellent work (Challenge).

Next, two German violinists. Arabella Steinbacher is no stranger and always delivers. Also, as a major violinist, she has recorded a lot of less known works, like Milhaud. Her newest Bach album (Pentatone) refreshingly pairs the 3 concertos (I hate issues that do without the double concerto, my favorite; here it features the equally excellent Christoph Koncz) with 2 significant Arvo Part works. And then a name that I have only previously encountered in chamber music recordings, Veronika Eberle. The Beethoven VC with LSO/Rattle (LSO Live) is very good, but the new, unorthodox and long cadenzas by Jorg Widmann seriously rattled many critics. I must say I enjoyed it!

Finally a male! Daniel Rowland, formerly of the Brodsky Quartet, is very active in chamber music. (Challenge) has issued several excellent recordings with friends. The most palatable one for most listener should be Exstasis, which is mostly Piazzolla. There are also a few tunes composed by Bandoneonist Marcelo Nisinman, who grew up with the master a constant presence in his house. No wonder the authenticity of his playing and compositions! The highest honor I can pay to this group is that they are the BEST tango quintet after the master’s own (and there are quite a few others in the same stable, but none measure up to this one)! On the same label Rowland has also recorded excellent albums of the music of Vasks and, the latest, that of Ukranian Silvestrov. Of the Quintet members, Ukranian Pianist Natacha Kuritskaya and Serbian Cellist Maja Bogdanovic have recorded albums with Rowland (and on their own) and I fully intend to explore them.

Speaking of the Brodsky Quartet, their Golden Oldies album (in celebration of their existence) of encores is more fun than usual (Chandos).

Keyboard

The big find for me is Yeol Eum Son. I don’t know what’s happening, but why so many complete Mozart Sonatas cycles all of a sudden? For me, her (Naive) recording goes to the top of the list, surpassing the recent Mao Fujita and William Youn. Compared to Leonskaja, she is less sumptuous but more naturally sparkling. For those who don’t want a Mozart mega-dose, her earlier recording of PC 21 with the ASMF under Marriner is impeccable (Onyx), and it closes with several solo piano pieces, including a superbly subtle K330. Her other Onyx and Decca albums are all worth exploring.

Since we were on Prokofiev PC2, I found another older but highly worthwhile recording (with the PC1) by unknown-to-me Ukranian pianist Anna Shelest and the Janacek Phil under Niels Muus (Sorel). Great sound and playing all around.

It’s very common now for pianists to experiment with improvisations and instruments like fortepianos, old pianos, even harpsichords and clavichords etc, but few has taken things to the dimension that Anthony Romaniuk does. On Perpetuum (Alpha) he plays on many keyboards, including synthesizer! Most are short classical pieces but some are improvisations. A string of short pieces (beloved by this chic label’s producers I must say) can lose traction after a short while but somehow Romaniuk maintains interest. I shall later explore his earlier album in the same vein, Bells.

Polish jazz pianists seem to make a specialty of playing Bach (like Jacques Loussier did long ago). Marcin Masecki’s new album with the MACV (on the obscure Warsaw Chamber Opera label) has one concerto each of Bach, CPE and Mozart. NML indicates “arranged by Masecki” but I hear only some embellishments and jazzy cadenzas. He has an earlier album of Bach concertos with pianist Piotr Orzechowski (Decca), on which he plays a Wurlitzer and Orzechowski a Rhodes! The latter instrument was played at a very slow tempo (surely due to the slow response), not suitable for all listeners, but a curiosity!

Polish Organist Julian Gembalski delivers a superbly idiomatic Bach Organ Concertos (despite the name, these are solo works) album (Musicon). These can sound boring in lesser hands, but here they live and breathe. Wonderful style and sound!

Chamber Music

Heading the list is the recording of the 2 masterpieces of Mozart’s String Quintets, K515/6 by the Ebene Quartet with Antoine Tamestit (Erato). Not since the augmented Grumiaux Trio (Philips) have I heard a more competitive recording! This recording shades out the very good one by the augmented Van Kuijk Quartet (Alpha) but the latter’s Mozart Quartets are just wonderful and among the best!

I listen to every recording of the wonderful Brahms Horn Trio. Among the current crop, my favorite is Marie-Luise Neunecker, as usual coupled with the Ligeti homage. How can this recording not be good, as it features the usual partners of one of my favorite violinists, Antje Weithaas (BIS)!

Anything by Tetzlaff and associates is not to be scoffed at. The latest is Schubert’s Piano Trios with Lars Vogt (Ondine), who has passed away recently. The tempo is slow, the playing detailed yet gentler than usual, but given the circumstances (of Vogt's passing), one possibly reads a little more into it. Worth exploring. For a different way of playing, from a different era, listen to the same pieces performed by Grumiaux, Fournier and Magaloff (Philips mono, on Tidal).

Speaking of the Brodsky Quartet, their Golden Oldies album (in celebration of their existence) of encores is more fun than usual (Chandos). Very sweet!

Saxophone
The classical Saxophone has basically been usurped by jazz. But it does not need to be so. A fresh force is Huw Wiggin. His new album Rhapsody (Onyx) features more new works than the older Transcription dominated Reflections and is better for it. I enjoy his new album better than many a new jazz album!

Either/Or: 2 Preamps
Recently, I was loaned a Nobsound (Douk) E6 Preamp, which uses the unusual 2J27S Direct Heated Pentodes. The chassis is very small and the tubes sticking out are big (almost size of a shorter vintage 6SN7) but the sound is big (Review here). Before this, I have been using the modified Eastern Transmission Audio (ETA). In a nutshell, the diminutive Nobsound has a bigger, bolder sound, bigger images, but less control. The ETA has somewhat smaller images but greater depth and better dynamic gradations.

I stream mostly on NML, which has a leaner sound sometimes. I also do Tidal, which seems fuller, but colored. With some recordings, neither seem perfect. Sometimes switching from one preamp to the other brings improvement, even change of view of the performance. Let me just cite 2 examples using albums covered above.

When I streamed the Van Kuijk recordings with the ETA, I frequently feel the sound to be a little on the white side. This is a consistent observation of the Alpha label. When I switched to the Nobsound, the strings instantly became just a little fuller sounding. Just what it needs. On the other hand, when I streamed the Schubert Trios with the Nobsound, things are just not as woven as I’d like. Switching to the ETA firms up the piano and knit things together.

You get the gist. Which one is more accurate? I don’t look at it that way. Truth, whether in audio or politics, has many facets. In audio, unlike in reality, we can search for truth as long as we want. Nothing is forced down our throats.

 

Eastern Transmission Audio Preamp II 6J4 6P3P Solen Wima

Click pics to enlarge.

Review: Eastern Transmission Preamp, Part II

Cheap Mods: My Two Preamps

Letter from Shenzhen (23-8): Materialistic Does Not Equate Costly

Note: 12/4/23: Due to the recent Failure of the ETA Volume Pot, this Preamp is now not recommended!

Eastern Transmission Audio Preamp, Part I

Part III, however, covers a serious failure of the volume pot. Highly annoying!

Part IV, on JAN GE 5670 tubes and more. Pot fixed.

In Part I, I mentioned I was contemplating mods. Indeed, even after I was pleasantly surprised by the very good results I was getting then, I still proceeded with my plans.

Since I had been using the thin, soft and excellent (dirt cheap too) Canare L-2B2AT as interconnect (here), I resorted to changing out the signal cables in both my Preamps with this Cable. BOTH Preamps employ generic Chinese shielded cables that are very thin (this makes them very easy to work with and solder). The Canare is already a very thin 25 AWG, so I estimate the ones in the preamps to be 30-32 AWG or more. This doesn't mean thinner is worse, but there's a limit, and quality of copper matters.

Eastern Transmission Audio Preamp (ETA)(Original Review here)

• Transformer Shock Absorption I refer you to my previous Dynaco PAS3 mod on how important it is to isolate transformer vibration. I don’t have much around, so I put 2 slabs of Heat Shrink between the 2 Power Trans screw terminals and the chassis.

• Cable Change I changed out the Input Signal Cables, the Cables from the pot to the board and from the board to the Output. For the first 2, I had to work around the Tiny Volume Pot, which is more prone to heat damage than larger pots. I incidentally found out the pot is 50K. While application of solder to the prongs is quick, I quickly learned it’s better to pre-tin the wires and the prongs before welding them together.

As soon as the first notes sounded, I knew the change was ALL for the better, and I should have done it earlier. As anticipated, sound was freer and fuller, more fleshed out in the mid-range, and bass was fuller too! Remarkable!

• Capacitor Change I procrastinated on this. The stock is (supposedly) red Wima (0.33, 400V). What the hell, I decided to buy some to try out as it’s not difficult to do. I bought 2 used 0.33 400V vintage TRW (RMB 17 including postage). Despite never having been a Solen fan, I also bought several “Solen”. At RMB 1.5 each (and RMB 8 postage), they cannot be the real thing, but they do look the part. The 0.33 pair I bought is 630V (but one is quite a bit larger than the other); I also bought 2 pairs of 400V ones, 0.22 and 0.47). When I loosened the Circuit Board, I noticed it said 0.22. I’m not sure if this board is from ETA. However, 0.33 shall give a fuller bass, which suits this amp. I thought about it and finally decided to install the 0.33 “Solen”.

Well, well, sound was just as expected. Sound became not only fuller, but more subtle and flowing in a way. In fact, bass now was quite awesome, tight and with heft. There was a downside. Treble was slightly rolled off compared to the Wima, partly due to slightly slower transients. But this SRPP circuit can take that. In fact, the Solen and Wima, real or not, seem to be both fine and similar in signature to the real things that I know well (e.g., the plainer sound of Wima and heftier bass of Solen). I’d think the 0.22 “Solen” and the vintage TRW would be both worth a try. When I get the urge perhaps...Right now, I’m satisfied! This is now a completely different amp from when I received it. And I don’t even have the urge to change the cheap Russian 6N3P, so finely detailed and musical it is now.

A few days later, I moved on to my other Preamp.

6J4 6P3P Preamp (Original Review here)

• Transformer Shock Isolation This Power Trans is larger and has 4 screws. So, I threaded a sliver of PVC cable skin (harvested from Mogami) onto each screw and re-bolted the trannie to the chassis.

• Cable Change This Routing was more complicated in this case. As noted from the Addendum to the article above, in contrast to the schematic, the Volume Pot is actually put last, before the Output. I saw no need to change all 4 Inputs, so I just changed one, from the Input to the Selector. Then, the Cable to the 6J4; then the cable from the 6V6 to the Volume Pot and finally from the Volume Pot to the Output.

Although both have high gains, this preamp has a diametrically opposite sound signature to the ETA. Nonetheless, the sound was also definitely significantly improved. In this case, it brought more clarity and detail and tempered a little the occasional over-luscious sound. Transient speed was also definitely improved. I’m very satisfied.

• Capacitor Change? Yes, I shall do it soon. But this circuit is more complicated and I’m not sure which cap would have the biggest effect. I shall inquire the builder. I’d think one of the 0.22 caps (stocks are generic; I’m thinking of using the Wima removed from the ETA for the job - wouldn’t that be just perfect recycling?)

Conclusions:

• 1. Cable change makes a big difference. And combined experience (not just these 2 preamps, also my FU-50 amp!) shows the Canare L-2B2AT does a very fine, even tempered, job. If your preamp sounds too dull or too bright (like many DIY efforts that use awful, silver-plated wires), it may just help. Highly recommended to all. I’d like to do the same with my APPL amp, but all the soldering joints are topped with some kind of red sealant that removal might be a problem (see pic in review article).

• 2. Cheap caps can sound good! In fact, I have heard just too many esoteric and crazily high-priced caps sound bad (in my considerable experience listening to DIY products, the more overloaded it is with boutique components, the more the tendency to sound wayward). Despite the stock cheap capacitors (mostly generic, with a few Wima, Bennic etc) in these 2 preamps, they sound reasonable, and the designers have voiced them within a budget. After the necessary cable change, caps could be icing on the cake. But keep in mind a pair of the 0.33 Mundorf caps would equal the price of the ETA preamp! Maybe cheap for you, but I’d like to maintain my sense of scale. Now, I don't actually encourage you to buy the cheap "Solen" caps except as experiment and with an open mind. If you have the time and curiosity, however, I'd welcome your feedback.

• 3. I didn’t test out the singular effect of transformer isolation as I have written about it before (see PAS3 article quoted above). I’m not the only firm believer, read the many positive comments left by the readers!

BRZ FU-50 Amp

Click pics to enlarge. The black wire is Canare L-2B2AT.

Review: BRZ FU-50 SE Amp, Part I
Letter from Shenzhen (23-7): Is the "Little" 300B a 300B at all?

Part II is very short, a Capacitor change for the better, embedded in another article.

Also, consult this article, which shows that the amp can do a much better job with even higher efficiency loudspeakers!

Part III covers 80 rectifier and even WE 274B use.

This is a long delayed “formal” review of an amp I have long used and have “previewed” before (here). It’s a highly deserving amp on its own and a tremendous bargain. Before, I had to write about cables to prep for my Eastern Transmission Audio Preamp article; just as I have to write this article to pave the way for my coming article on moding my Preamps, which is highly fascinating, to say the least.

The Reputation of the FU-50 Mostly in Chinese media, FU-50 has been touted as the “little 300B” because it was said that when operated in triode its curve is almost the same as 300B.

https://m.tb.cn/h.UK1tryS?tk=Au3xd8ffgnn

TWO Versions This amp is widely available everywhere, under many vendors. The FU-50 is operated in Triode mode, said to yield 8 wpc. There are 2 versions with different drivers. I deliberately chose the pentode driver version, for reasons I alluded to here and here. The Soviet 6J8P (6米8) has western equivalents, like the 6SJ7 (a classic WE era 6J7, with different pin-out [without the top cap]; so, in a significant way, this design bears a resemblance to the WE 91A circuit, which has the 310A/6J7 driving 300B) that is favored by many SE amp designs (like my Softone/ICL amps, here and here). There is also a version that uses the double-triode 6N8P (6SN7) as driver, but that’s a different animal, which you might like if you own good old stock tubes that are now very expensive (I do, but not here in China). The 6SN7 design brings it too close to many other 300B amps, like my Sun Audio (and its myriad clones here in TB). You, however, depending on the tubes you have, may want to choose otherwise. At around RMB 900, it's a bargain.

Build Fabulous! It’s a very beautiful amp, and smaller in size than usual (though slightly larger than my Sun Audio and ICL). Better than many “high-end” offerings if you ask me. The milled aluminum is just luxurious. Inside, the amplifying parts sit on a high-quality circuit board, with good parts and wiring to the rest. Yes, a choke. Nice. It’s also gratifying to see that, in contrast to the others, the amp actually uses a quality signal cable, my preferred (and dirt cheap) Canare L-2B2AT! Great! On the other hand, if you DIY, you can buy just the board, cheap!

Stock Tube Sound It comes with a Chinese 5Z4 instead of the Soviet 5U4M pictured (yes, the TB page says this in small print at the bottom). It comes with Soviet 6米8 and very well -built Beijing FU-50. Sound was very nice out of the box (perhaps slightly lean).

Reliability Absolute. This amp runs for umpteen hours a day, with no problem. I use it with my Beydas LS3/5A.

Issues None. Which is why I use it as routine. My APPL suffers from a loose socket problem that emits annoying popping noises occasionally, not completely eliminated even with tube shield on (here, which however, is not present in Shawn P and R Salamat’s samples). Sonically, it’s a different matter, as below.

Tube Rolling I have 3 amps here. The Aosibao came with a Soviet 5U4M, which I sometimes use in the others. For shared use, during 11.11 I bought what I considered to be reasonably priced rectifiers here: 80’s Philips 5R4WGA (GT bottle; RMB 164); early Chatham 5R4WGA (potato masher; RMB 145 - this is a great bargain!); Tung-Sol ST 80 with adaptor (RMB 244 + 20). I may write an article on rectifiers later. Suffice to say, all of these sound better than the stock Chinese 5Z4. The stock Soviet 6米8 is actually quite good, steady and spacious in sound, though with smaller images. My sub, the Raytheon 717A (RMB 400 for the pair) sounds very different, as it imparts more texture and solidity to the sound, bigger imaging too though the soundstage is perhaps not as deep. Too bad I don’t have the WE version here (used in my Yamamoto 45 amp). I finally re-capitulated too and got the Soviet 50’s FU-50RY (RMB 140 per pair) and they further improved the sound in terms of texture and dynamics. So, you can see that, even discounting the costs of the rectifiers, which I use in all 3 amps, there is still a premium to maxing out the potential of the amp but it's small (RMB 540, which is a little more than half the price of the amp). It should be said that the stock tubes are decent. Better tubes improve things a bit, but perhaps not on the transformative level, so one should buy wisely. For the rectifiers, the 5U4M has a drier sound (not nearly as good as their ST bottled ones). The 5R4WGB is significantly sweeter; the 5R4WGA (potato masher) a little more detailed and forceful. I mostly alternate between the two. The 80 with adaptor is a totally different animal - softer but so rich and sinewy; I sometimes enjoy it at nighttime.

vs 300B So, is this a small 300B that is deserving? Well, yes, but it depends. Even in stock forms, the APPL (which, despite its quirks, I rate very highly) sounds a bit more organic and luscious, at a little more than twice the price. With all the tube upgrades, the FU-50 closes the gap, but not completely. Tonally, the 300B is still more sophisticated. Although the FU-50 is rated at the same 8 wpc, I don't think so; power is noticeably a little short of the 300B, and its clipping/saturation are somewhat less benign than the 300B. But it’s very revealing of what’s upfront (my next article on my Preamp mods). Suffice to say, at its best, for not much money, with or without tube upgrades, it’s a winner. There is NO SET amp that can put out as cheaply as much power, and with as much finesse (I'm pretty sure it outshines SE EL34, 6L6 etc). If your budget is limited, this is a prime consideration. Even if you can spend more, this is a great lesson on how much can be accomplished for so little. Mind you, I’m comparing it with the APPL 300B, which I rate higher than many bigger named 300Bs (but quirky!). In fact, the more I listen, the more the BRZ seems to sound like the usual DHT amp, whereas the APPL sound has qualities that are hard to describe (may be another article). So, an average el cheapo 300B might have a harder time facing up to this amp. All this is based on the harder to drive LS3/5A. On my more efficient Sansui floorstander, the FU50 faces the 300B on more equal footing, with an exciting drive and transient prowess, but I haven’t done that in a while (initial impressions)

There have been significant changes in my system. Simple cable upgrades to my Preamps (article to come) have brought them to much higher levels of performance. Also, the addition of a pair of Xinshi 新时 597 passive “supertweeter” has also snapped things into focus. The system is highly satisfying. Previously, occasionally I wondered if the BRZ is a little on the lean side. No longer. I may yet to do a little cap change to see if I can extract even more out of it.

Recommended if you have tight budget and efficient loudspeakers, do not have too much real estate and prefer a tube sound that is closer to neutral rather than obviously smoky or cloying.

Keep in mind, greater than 90% of my time are spent with this amp (I listen for more than 10 hours a day). If it's good enough for me, it may also be for you!

Schematic

Dynaudio Excite X32 Lab12 Preamp Mark Levinson ML9 Weeput Bluetooth Cambridge DacMagic Plus

Click Pics to enlarge. Dynaudio Excite floorstander. Linn loudspeakers sold. Right rack ML9; center, Marantz, Cambridge, Weeput; left McIntosh combo.

Letter from Hong Kong (23-4): ELO Home Visit, From Below-Par to Highly Enjoyable

As I was instrumental in the selling of his Avalon Avatar to my friend, I have known Seven for almost half a year. Since then, we have been texting on hifi matters. He has a tendency to buying and selling often, sometimes reselling quickly, and equipment come and go like merry-go-round.

At first the performance of his setup was quite mediocre at best and did not arouse my interest at all. I admire his courage but the purchases he made are not things that I would usually consider. Recently, when he said he would like to try McIntosh amp, I told him about my bitter experience with my Dynaudio Compound 2 and McIntosh MC7300. Of course, like many Hifi lovers, he bought it anyway. Luckily, he actually bought the Dynaudio Excite X32 and Lab12 Preamp based on my recommendation.

He said he compared the X32 with Focal floorstander and Wharfadale Jade 5 and preferred the Focal (a name I also respect) to Dynaudio. He also told me the Lab12 Pre was not as good as his other DIY preamp.

Well, sometimes you never know! I just want to verify if what he said is in line with my ears, so one day I went to his rented space purely for hifi listening (what a luxury!) after work since it is just a stone throw away from my workplace.

Powered by his McIntosh combo and Marantz CDP, we tested the Focal against the Dynaudio. It was apparent in the interim the sound had improved from quite mediocre to acceptable, though still with some booming in the mids and lows. My preference was with Dynaudio and, after prolonged listening and sharing views, he came to my views and eventually sold the Focal. The Lab12 Preamp was not played on this occasion.

After a very short period of time, he bought a classic Mark Levinson ML-9 Amp and hooked it up to the Lab12 Pre. I revisited, bringing with me my Luna Orange speaker cables (that I have previously reported on) to see how it would sound in his setup. On this occasion, the CDP sounded OK, but was nothing to write home about. Then, I spotted a tiny Bluetooth device (oddly named Weeput, 小沛知音, from China) that was hooked up to a Cambridge DacMagic Plus. I immediately streamed Tidal from my cellphone to his BT device. Sound completely trumped his Marantz CDP, which in comparison sounded tired, veiled and lacking in sparks. While the McIntosh combo sounded rich, fleshy, slightly coloured and musical, Lab12 Pre/ML9 provided more details and better imaging, but with a leanness and slight austerity that was not to my taste. Luna Cable came to the rescue and once again shined with its true orange colour. The sound became more organic and musical, with good bass and convincing soundstage. Everything began to make sense, PRAT was preserved, and I was starting to enjoy the music tremendously through the BT device and Tidal music - what a transformation from before! Yet, a trace of hadness is still detected .

I also suggested he paired the Lab12 Pre with his McIntosh Amp. Surely, the next time I visited, it was hooked up and immediately uncovered a perfect synergy - the neutrality and speed of Lab12 paired perfectly with the lush and big sound from McIntosh. Previously on the verge of being dumped, the Lab12 Pre had become the last piece of the jigsaw puzzle that completed the picture! I am happy that the Lab12 has found a good home!



I then played the songs from my playlist, with different genres, and Seven was enlightened since I have opened up a whole new world of music to him and he found it so fascinating! He said he had never heard his setup's performance to be so good. He has upped his understanding of music 升呢 big time lol. Once you taste the best, you can no longer settle for less (not quite yet, but I like the rhyming)!! But, right now, I can spend extended time to enjoy music at his place, and that does not happen often to me.

The surprises for me are the superb quality of the Weeput 小沛 BT receiver/DacMagic combo as well as the quality of McIntosh Amp (all it just needs is the right preamp to pair with)!

Incidentally, I also found out on why before he and his friend had preferred Wharfadale. The bass coming out from the speakers was big and with copious quantity. However, to me it's lacking in finesse, timbral accuracy, details and shimmer. Musicians played as if they just had a hearty meal and were ready for a siesta, which to me is a big NO. What really shocked me was that I found out why his peers prefer that type of sloooow sound. They mainly listen to Canto pop with limited dynamic range! They seldom listen to any other types of music and actually enjoys SLOW sound even when it is supposed to have PRAT!

Shenzhen Audio Show III

Letter from Shenzhen (23-6): Shenzhen Audio Show, Part III

Roll down or click links for Part I and Part II.

Note: Coverage of the show follows no particular logic: Very good is Green; Good is Yellow; and Average is Red. Believe me, I'm very lenient! More so towards others than myself!

***

Raidho CH Precision HK distributor Roksan (no relationship with the UK brand) showcased a large Danish Raidho with Swiss CH Precision. Smooth and balanced sound that I recognize as CH. What’s better than their showing previously in HK is that Raidho blended in completely whereas before a bit of disjoint could always be detected (common problem of ribboned loudspeakers).

 

Simaudio Scansonic Also Roksan offerings. The Danish Scansonic were driven by Canadian Simaudio. While the sound was good, it was not quite as smooth as the Raidho room. A trace of grain was evident. What’s with these Danes’ obsession with ribbons? Don’t forget, there is Borrensen too (formerly with Raidho).

Showfeel 宿优 This is a bigger soundbar, and the sound was surprisingly enticing. There is a down-firing woofer, and the sound was coherent. Like the popular Tivoli, there is also a model that is a stereo pair. Much cheaper than Western rivals, like B&W and Meridian, it deserves to be better known.

rossofiorentino Hegel Gold Note HK distributor Changye showcased the striking rosso looking rossofiorentino with Hegel (which has a reputation of easily matching most gear). Sound was quite balanced and easy to like. If you look at the pic, the Gold Note CDP (or transport) shows total time, so it was not playing. Sound then had to have come from the Hegel Streamer that displays Roon (yellow paper star) as I don’t see a Hegel CDP. Not sure if GN DAC was used. At the other end of the room, on silent display were French Atoll electroniques and Finnish Penaudio loudspeakers.

German Physiks In HK this brand has a small presence, and at shows we usually see a small room and a smaller model, so I was pretty happy to have encountered this pair of much larger ones (not even close to flagship I was told). Due to the size, it was understandably placed along the long wall in this room of limited width. Driven by its own massive electronics (and Esoteric CDP) sound was quite good, but with piano recordings the bass was not the most focused. Given the short distance of listener to setup, I still rate it a good effort. As a good friend had a pair, I know the sound quite well (and quite like it), and so I chatted with the 2 salespeople, who were ultra friendly and perhaps happy to talk to people (this was not one of the more popular rooms). Of course, we talked about its omni-directional rival MBL. I told them how much I disliked the MBL electronics, and they laughed and told me an anecdote about how MBL self-destructed its tweeters at a show. Funny guys!

Xuyingge Audio 许英谔 Named after the designer, who is quite old now and a veteran of electronic designs. They make everything in this room, from Digital front ends to amps to loudspeakers. All with reasonable price tags. IMHO just too many loudspeaker models, and the finish were not very good. A larger floorstander (last row, second from right, with a black sign placed on top) was playing. Sound was not bad, good bass but a kind of grainy on top.

Jolida Neat I was surprised to see Jolida here in China. It had had a long presence in the West, well known for their budget offerings, but not much seen in HK. From 2017, it had morphed into Black Ice (pricier). In this room I was disappointed that no Black Ice (or Glass) could be found. Sound with the small Neat bookshelf was decent, but I wished I had heard the iconic IOTA on silent display.

Soundaware 享声Amphion Soundaware is from Nanjing. Outside of my radar but likely fairly well known in the west and in Singapore (where the “US” website is based). In the small room the streaming and amplification gear did a good job with the Finnish Amphion loudspeakers.

Franco Serblin Prima Luna Although Franco Serblin had long passed, his company (as well as his former one) is still going on, but the smaller products on silent display are getting even weirder in looks. Man, are we paddling or playing lacrosse here? The large floorstander driven by Prima Luna tube amps sounded good, but not exceptional. For me, there are many Chinese amps more interesting than Prima Luna, like those from Analog Sound and Line Magnetic in Part I. Mind you, Prima Luna is made in China too, 

LALS Kinki LALS is a Taiwanese company with Shenzhen base, sold in Europe too. The Taiwanese proprietor told me the factory used to make JBL drivers. They have kind of a professional, or TAD-like look, and are horn based. Some higher models have alnico magnets and silver coils. Sound with Kinki electronics and a Chinese tube amp was only so-so. I think not enough power. We heard the smaller model unfortunately. I'd like to hear these again under better circumstances. I told his wife the negative connotations of “kinky” and she was really surprised. What's in a name? Plenty!

Audes Audio Analogue Estonian loudspeakers Audes (with AMT) looked very nice. I was really surprised that Italian Audio Analogue had really gone upmarket! Long ago, I had their Puccini integrated for a little while. Not the most controlled but musical. At the time the Bellini/Donizetti separates were the next step up (not that expensive). Forward to now, the last 2 named opera composers are in Anniversary editions, with much heftier build and price tag. Sound was, as expected, on the warm side, and quite decent.

Quested Mymei 艾美 Mymei is a company that specialized in digital streaming. Through the UK Quested active monitors the sound was not bad.

Humble Offerings from Elac and Musical Fidelity. Did not stay.

Silent Display of Kreisel and Starke, unknown to me

Not Acapella, I assure you (not that it matters). Chinese loudspeakers and amps.

Didn't like the looks and sound when I peeked in, so left.

***End of Show Report***

Notes: 1) There were quite a few rooms of Chinese Cables and Power Conditioners, which I just skipped; 2) I scanned through the top floor of AV, nothing much of interest; 3) I also did not cover the many rooms that sold LPs and CDs, though I bought 3 bargain LPs @rmb 15 each, and I don't even have a TT here - it's kinda like Dr. Strangelove's arm, which hasn't completely lost its memory.

Postscript: 1) This being a show that is manageable in size and not very crowded, I actually got to sit down and appreciate some of the stuff. So, I get to report more in detail. Thumbs up; 2) average sound is definitely superior to that of the large HK AV Show in August. It's not a coincidence as HK exhibitors Roksan and Changye had better sounds here than in HK; in HK I often do not stay for more than a minute because of subpar sound; 3） There are a lot more of interesting Central and Eastern European Hifi here than in HK, but then I haven't really been in a HK show for a few years. My last coverage of the HK show was in 2015! 4) Almost no German presence here! That's just fine with me. No time wasted with MBL (electronics), Burmester, Symphonic Line, Einstein, Clearaudio, etc. More than 90% of the German Fi are not good sounding nor interesting to me. Ditto US and UK Fi. No Naim, Audio Note, Wilson, McIntosh, furnaces like VAC, VTL etc. We all need a change of scenery, but some of the brands I mentioned may perhaps show up in the large Guangzhou show in May, which I may or may not attend.