Nobsound E6 Part II Douk

Click Pics to enlarge. Top, Andy's JBL Station. From L (top) to R (bottom), Technics SP10 w/ Dynavector DV505; Garrard 401 w/Odyssey RP1; E6 on plinth; Dared 2A3 amp.

Nobsound E6, Part II: Cap Mods, Feedback from NYC
Letter from NYC (23-1): Update on Andy’s System

Update 4/22/23: Empty circuit board photo added. Shows which cap is which. 

Note: Part I is the Main Review. For those who first encounter the E6 here in this page, please read it for main info - this is a follow up, but it’s full of useful info. Part III, on Phase Reversal and more on Microphonics, has also been published. 

The Miracle Continues 

As I mentioned in Part I, the Nobsound E6 is that miraculous product. Here we strive to make it even better!

Capacitor Mods As I mentioned in Part I, given the tiny size of the PCB that is studded with surface mount components, the only mods possible (within the ultra-compact chassis) are the 4 coupling caps. The stock is pretty standard generic MKP2. As you can see from the pics, on the side that has only one, there is no concern. BUT, on the side that has 3 jammed close together real estate is a real problem. Make sure you scale with the tube socket in mind and you shall see how little space there is.

Which Cap is What They 4 grey caps are Input and Output Coupling Caps. Value is unusually high at 1.0 uF (5% tolerance, 250V). After I un-soldered them, I noticed they are numbered C1, C2, C3, C15 on the PCB. This is highly unusual. In the usual circuits, the left and right are named with some symmetry, like 12 for R and 22 for L; 13 for R and 23 for L. Not here! The PCB tracks are sophisticated, double sided, sandwiched and copper traces are not visible except for slightly raised outlines. I could only trace C2 to the volume pot, and so it’s an input cap. I inquired and fortunately got an answer after I did my mod: C2 and C3 are Input Caps; C1 and C15 are Output Caps. Now, that is helpful for planning.

https://m.tb.cn/h.UsNmXVa?tk=bpX3dlUIHxn Capacitor Choice I cannot emphasize enough the importance of this. I don’t mean (preconceived) sonic merits, I mean size!!!! 250V caps are smaller than 400V ones, but they can still be pretty big. There is very little room. I ordered 4 types (dirt cheap), and the most “expensive” ones, so-called “Solen” that I used with success to mod my ETA Preamp (here), were just a little too big, and I finally resorted to the Audiophiler ones. I replaced all 4 with same. For US (Parts Express) and Europe readers, perhaps check out the cheap and good “German” Audyn caps which I used to modify my Dynaco PAS3 (here). The smaller the better! Dispel the thoughts of using PIO Jensen, or Beewax or whatever! Won’t fit! You have been warned.

While we are on boutique caps, most of them cost as much as, or more than this device itself. It’s your choice, but I think dollar caps today sound very good, as per my Dynaco and ETA efforts linked above. And, most of them, French Solen or German Audyn, to name just 2 mentioned here, are for sure made in China. The rest of the deduction you do yourself.

Well, here’s actually a thought. For one of the caps on the crowded menage a trois side, you can solder wires and move the cap to the other side (affix it with blu-tac or glue), which has more space. So, perhaps it’s possible to have somewhat larger caps after all...

Sound The Audiophiler Caps cost RMB 3 (for 4). One can extrapolate how much the stock one's cost. BUT, the effect is mightily impressive! Everything got significantly better. It’s not a question of better high’s or better mid’s or low’s (though it is better in all of these, but nothing predominates). No, it’s a much more organic kind of better everything, including control, integration, dynamics, noise level and, ultimately and very simply, how much one is at ease without noticing this or another deficiency. After the bar is raised, I really think this tube can do no harm whatsoever. Proceed with confidence! A rough estimate, the magnitude of improvement by cap mods is as much as moving from the Chinese tubes to the Russian ones mentioned in Part I.

Ultimate Mod Fantasies Well, one solution is to move the PCB outside its straitjacket of a chassis! Mount the PCB in a larger box, use rubber washers to isolate it and for shock absorption. Use whatever caps (even huge vintage oil caps) you like. And, yes, solder wires to the PCB and use a “better” pot is a possibility. Personally, I look down on expensive resistor ladder pots. Many of us prefer the more natural sound of carbon pots (yes, even Shindo). It’s your move. Why are we talking about this? Well! This little thing is worth it!

E6 fever in New York City

I’m really shocked how the E6 has taken my NYC friends by storm.

Lenco TT with STAX (and SME).

Andy How come I know so many Andy’s? Well, for regular readers, this Andy is not the HK one I mentioned in my recent Guangzhou Show reports. He is my NYC analog guru and leader of the gang there (we have a wechat group). Regular readers need only to search this blog and find my numerous NYC articles (here for one). Well! Andy and I know each other’s taste very, very well (yes, we have small differences, but they are highly consistent and reproducible, and we know what the other will feel). As reported before, he spends his daytime downstairs with his 2 horn systems. As purveyors of DHTs, of course we are all interested in the unusual E6. And so, Andy bought one - and really liked it:

• He mostly uses Analog. In his Dining Room JBL Station (pics in this article, previously reported in detail here, but it is very different now), he employs three turntables with 4 tonearms: 1) Garrard 401 w/Odyssey RP1; 2) Technics SP10 w/ Dynavector DV505; 3) Lenco Double Decker w/ Stax and SME 3012 Series One. Except for the Stax Cartridge, the TT output goes into Citation I, then via Tape Out connects with E6 which then drives the Dared 2A3 amp. He hasn’t done much comparison, but his gut feeling is the E6 sounds as good as most much of his preamps.

• The Stax setup deserves a special mention. Andy found out that the E6 almost miraculously can serve as the 10 db Booster amp (the E6 is around 16 db, with a volume knob) for his Stax ESL cartridge (reported in detail here; this cartridge is highly unusual, amplitude device, no RIAA needed; the output goes into a decoder, which must be used, and then into a Booster amp. The original Booster was FET, but Andy said the E6 is simply better!

• In his Altec Station, he has also briefly tried out the E6 to good effect. With CD, his Sony SCD-777ES benefits from the warmth of the E6.

• 
  In his main mega system upstairs (reported in detail here), Andy has tried the E6 to good effect as a booster for phono going into the ARC Reference 2 Line Stage. As the noise level is low, he finds it very useful wherever signal boosting is needed. The latest is this: Quote: “...I’m testing one between the equalizer of the DS E1 optical cartridge and ARC Reference II line stage. It’s doing a good job toning down the solid-state characteristics of the IC op-amp equalizer...” Here though Andy finally detected some microphonics, which he said were largely absent downstairs.

• Andy bought a few more to use in all his systems. And our friends have followed suit! The cohort so far has bought >10 and have depleted Ebay! I hope more reports to follow.

Mark Now, this is yet another insane friend whose big systems I have reported in detail before. Well, he bought one and then 3 more! See right screenshot for his comments.

There are more to come later from the other fellows...

2J27 Supply Woes For us, and for the foreseeable future, buying a few tubes is not a problem. But for a popular manufacturer, which likely buys 10K tubes at a time, it’s a big problem. There’s no great stash in China, nor Russia. So, in my estimation in a few months E6 shall not be available. If you are interested, now is the time to act.

Summary

• A great product Our NYC friends have all experienced very high-end before and together we are still stunned by the performance of this little thing!

• Serving as Booster Amp (or buffer) To sum Andy's experience, the E6 is worth trying out wherever you want a little buffering warm sound, or extra gain of up to 10+ db. It can serve well in many circumstances, particularly for analog fans, all thanks to the excellent engineering and the LOW NOISE (when the tube is good). My thinking: actually, all these fellows own several preamps and others could possibly fill the same shoes (but many of their vintage ones are noisier). But the difference with the E6 is that it's tiny and one is much more inclined to use it rather than pile up another big box into the system. A connected E6 looks smaller than the junction boxes on some interconnects (think MIT, Oracle etc).

• Microphonics is an issue that still looms on the horizon. So far, the NYC crowd did not have much microphonics, and they haven’t even switched to the Russian tube yet. For me here, as detailed in Part I. I use Russian tubes and don’t have the problem anymore. But we're on the watch for it.

• This is the kind of product Cheaptubeaudio exists for, and we are proud of really exploring it in depth. We have our author Shawn P to thank for it. It was after talking to him that I decided to try it out (chronicled in Part I, link on top of page). Incidentally, Shawn P has also gotten one and in due time we shall have his experience too!

Andy's Decca Cartridge through Citation I and the E6 (see setup above)!