Letter from Shenzhen (24-2): 3 Preamps, 3 Amps and 2 Loudspeakers
Douk T8 Pro, Part I
Douk T8 Pro, Part II here
Why should you be a long term reader of this blog? It's very simple. Aside from the fact that very very few trade or e-sites refuse monetization (think the garbage ads 6 Moons pile on you page after page, which is why I hardly read them and try never to cite them - I despise them, and shame on you if you read them regularly for free without thinking about your mental cost), very few audio sites re-visit audio equipment regularly (Stereophile commendably has some periodically and HiFi News has very good referencing to older versions too). Very few sites even mention older equipment (Thumbs up for Stereophile to continue to upload their vintage contents, and HiFi News to have Tim Jarman's Column on vintage stuff). We do here, and we sometimes re-think our opinions. And you shall find some examples below if you read carefully. Grant you, we mostly "review" el-cheapo new stuff or re-visit older stuff, but we do it very seriously. We tell it like it is, over a long period. This article is both an update on some equipment previously covered, as well as the introduction of 2 new Preamps. Not earth shattering things, but interesting nonetheless. As for music, at least for classical aficionados, our coverage is concise but very good.
In fact, I think the best thing about our approach is to tell you how to go about it, or rather how we go about it, not what is better than what. One can learn from the most simple experiments. To achieve good sound, one must listen a lot and read less (apart from this site, since it won't empty your wallet, LOL). Especially, you should not read sites like Audioscience. The measurements are OK, but the opinions are trash. Subjective evaluation is kintergarten level. I have only contempt for them. But they sell. It's a pity Chinese manufacturers routinely send things to them, even high end stuff like Matrix.
First, some catching up, or what I'm doing.
2 Loudspeakers (Beydas/Stirling LS3/5a Redux)
I direct you to my article that describes when I just came back from the US a few months ago. My Beydas "LS3/5A" "11 ohm" (basic info in Chinese here) sounded deadly dull. And I spent a lot of time to get the "old sound" back. It came back eventually, but I never was sure of why. Such are the vagaries of HiFi sometimes (whole process described here).
BUT, I got a new angle maybe a month ago. I swapped in the "15 ohm" Beydas "LS3/5A" (basic info in Chinese here), and the initial sound was not good at all either. Yes, more open in the treble (it has always been the case) BUT seriously deficient in mid-bass and bass ("official spec" has it as 10 db less extension than the "11 ohm"). Now, this was a virtually new pair, because when I went back to NYC last time, I gave my run-in pair to Andy. As I ran them in over a month, the sound gradually became fuller and some useful bass emerged. Right now? It's marvelous! I just listened to Sibelius Symphony No. 4 (Gothenberg SO/Rouvali, Alpha). This is a heavily brooding piece. Although this version is distinctive and lighter than usual, the double bass must have impact and, when partnered right, it does. In absolute terms, with the 3/5 it's just a hint, but that is more important than anything else. A hint of deep bass is a tactile and suggestive bass, very worthy (even the real LS3/5A is like that too, just a hint). Wonderful!
Yes, right now, despite the lighter bass, the "15 ohm" sounds better than the "11 ohm" but it had on occasion been the opposite before. One thing I did think of: If you haven't used a loudspeaker for a while, it takes a while for it to re-capture its former prowess. YMMV. But, if you use flea powered amps like I do, it makes sense.
2 Amps (BRZ FU-50 and SE 6L6) and Another (APPL 300B) Redux
I had spilled much ink on these 2 BRZ amps, and they remain my daily staple. It's really astonishing how much improvement I got from "upgrading" the stock Rifa caps with USD 0.25 "Solen" (here). Both opened up considerably in soundstage as well as enhanced in tonal opulence! The FU-50 (basic info here) remains ahead in most respects (though the 6L6 [basic info here] is likely fuller in the bass). Both are just super bargains! Now that kits like Elekit (which I have long championed before but have reservations now) have gotten over-expensive (and unnecessarily big) I'd urge starters to consider these 2 very cheap amps (that come with useful tubes, not as extras). Mind you, like my favorite Sun Audio, these are simple, pure tube in the signal path (which I usually prefer, but not always), whereas Elekits now are very much solid-state-regulated in the control grids to achieve higher power and better dynamics. I actually have no qualms about things like solid-state use like constant current source (my ICL amps use that); it all depends on the resultant sound. I do think I can hear a trace of ss influence in the Elekit, but not in ICL. As for the cheap stuff here, as you can see from the links, aside from swapping in other tubes (still cheap), IF you can solder and change just a wire or two and swap a cheap cap in you can gain a lot!
Unlike Aiyima and Douk, with whom I have some kind of loose relationship (always declared) I have none with BRZ. In fact, I probably frown upon BRZ's voracious replicas of solid state FM Acoustics at super-bargain prices (though I'd not mind to hear one in my own setup if I get the chance). Price is their advantage, but I do believe they have a certain know-how: to make the best sound just above the technical safety red line (and that is why I'd NOT recommend you to plug in KT66 in the 6L6 amp; I have GEC KT66 but I'd not use it - also as US 6L6GC sounds just delightful in this amp!). Within limits, these amps run in my system hours a day for months without any problem. That's good! I've QC'ed it for you (and my samples are like yours, just randomly ordered from the net), provided you stick to rules.
But hierarchy remains. The Ultralinear 6L6 (or EL34) is still not as tactile as the FU50 run as Triode, and the FU50 still does not have the full sized presence of the APPL 300B amp (here, as yet still bone stock!). But switching between them is fun, and it reminds one that Ultralinear is not quite Triode, and running a Tetrode/Pentode as Triode is not the same thing as a Direct-Heated Triode. This has always been my long-term belief and this humble trio actually confirms it. There's no end to comparisons, and this blog compares more stuff than others. My point is you can learn a lot from even cheaper equipment (provided they are good). If you buy all 3 of these it's still way cheaper than a stock Elekit without tubes, but I wager you learn a lot more.
New Production Tubes
ALL these sellers out there say to you, this 300B is better than that one but few of them have really heard the old-stock WE300B's. I tell you ANY new one will not match up against old stock. I refer you to my recent article. That's not a sound you can get from buying an expensive replica tube today. So much nonsense out there it's really astonishing! IMHO, one should start with an honest and reasonable modern 300B tube, like the affordable Linlai that comes with my superb APPLause 300B amp, or a Russian basic tube. All so-called upgrades, like graphite or mesh plates, or gold pin this and that, sound different, but better? Not to me. YMMV. New "Western Electric"? Takatsuki? No thanks to all of them. In case you're interested, here's a 300B Shootout, from more than 20 years ago, LOL!
If someone has the dough, more power to him! Spend a lot on tubes is OK, but I'd buy only old-stock tubes (for 300B, WE before early 80's). Even if I have the dough, I'd NOT buy any of these boutique replica power tubes (be it 300B, 2A3 whatever). This is to emphasize that it's ridiculous for someone on a budget to spend more on tubes than the machine. Put the ridiculously priced current production "WE" 300B in an Angela amp and it's still an overpriced mediocrity. Better, put them in an Elekit, but it's still an Elekit. This is true for boutique components too, be it expensive caps or resistors or even transformer swaps. There is only so much improvement one can get from tweaking. Cheap mods are a lot of fun; expensive ones almost always end up in disappointment. No matter how you mod a Subaru it will not be a Ferrari; better enjoy the Subaru as it is!
Unlike most reviewers out there, I have been a tube addict for over 30 years, and I have a huge stash of very worthy old-stock tubes (and even more lesser ones, LOL!) In terms of tubes, I can max out the potential return in almost any amp. I can tell you what's a worthy upgrade and what is not. Driver tubes are worth experimenting with. As one goes down the line, the tubes become more useful. It's always good to have a few 12AX7 and 6SN7 around, for example, as they are used in so many amps. I sympathize with beginners on a budget. They read everything on the net, and end up buying different Russian and Chinese tubes of little import, when they should take the bigger step and bid on some good used old-stock tubes on Ebay etc. Power tubes are more problematic but, as I say, I find modern boutique tubes underwhelming. As mentioned above, I'd not spend too much...Last, incidentally, personally I feel Russian and Chinese 300Bs are very good tubes because 1) they have been making these for decades; 2) perhaps Triode are easier to make than Tetrodes/Pentodes with their additional elements; 3) I bet you Chinese 300B parts are used in many other boutique 300Bs. There is a huge amount of undesirable trade secrets out there. As for other DHT like 2A3 and 45, modern ones are just basically tweaked out 300Bs.
That's a lot of digression. Now to the Main Course.
3 Preamps (Eastern Transmission Audio [ETA] 6N3, PJ Miaolai SA-1000, Douk T8 Pro)
This came by in an unusual way. As I tube rolled the BRZ A08 6L6/El34 Amp I employed some better sounding but lesser gain tubes, like the 6SN7/L7 (with adaptor). As detailed in the link above, I prefer the larger envelope tubes (as usual). Which means there's an opportunity to use higher gain tube preamps. As mentioned in the link also, I tried the ETA 6N3 Preamp, but its defective volume pot makes it impossible to get a proper volume.
So I dragged in another two candidates...both are hybrids, tube buffered IC Preamps. Both are debutants here.
PJ Miaolai SA-1000
I actually still don't know why I bought this. During a previous 11.11 it was just so ridiculously cheap at barely over 200 RMB (around USD 30) that curiosity got the better of me. I actually got it before I got the ETA 6N3.SRPP Preamp. Reason? This came with a pair of Russian 6N3 so I later ordered the ETA without tubes at a savings of 50 RMB. Cheapskate, yes!
This is a Preamp, with 4 Inputs and 2 Outputs. It's based on the N5532 Opamp (not easily replaceable). It sports dual Tone Controls and Headphone Output. It runs on 12V DC (I used my own heftier SMPS PS). One Russian 6N3P in each channel serves as buffer (probably just paralleled, unlike the ETA's SRPP). More in pic at bottom. BTW, there is a new version with Bluetooth and remote control. Caveats The RCA sockets are of the most "basic" quality, which is true of many Chinese products at this price level. The outer casing of one got stripped as I pulled my MIT T3 interconnect out. Yes, this happened to my 6J4/6P6P preamp too. On both, 1 down, 3 to go. Make sure you don't use connectors that grip too tight.
When the PJM arrived, I fired it up and was assaulted by the crazy high gain and grainy sound and basically put it aside for a long long time. I never thought I'd write about it. I basically wrote it off!
Fast forward. I poached the stock Russian 6N3 for the ETA Preamp. At first, it was not so good, but after some mods and a hiatus, it was suddenly OK (chronicled here). And so I enjoyed the ETA for a while.
Fast forward to now. Since I could now use a higher gain preamp with the BRZ 6L6 Amp I decided to give this PJM Preamp a try. I put back in the 6N3 Russian tubes and was surprised. Perhaps due to the fact that I have run the tubes in thoroughly in the ETA, it had become much smoother. In fact, the run-in Russian 6N3 (and perhaps the run-in preamp) seems to be be fairly smooth. Too bad I don't have any WE396A/2C51 or even 5670 around (not even in HK).
vs ETA Comparison with the ETA (both using the same set of Russian 6N3) was fascinating. The all-tube circuit ETA (SRPP), which has had its caps and hook up cables modifed (link above), sounded not quite as fast as the also high-gain PJM. But the basic sonic signature is very similar, not surprisingly since they use the same tube. The midrange is virtually identical. The ETA has a little more top-end air and nuance, but turning up the Treble a little on the PJM brings the two closer again.
Headphone Output I tested it with my Grado SR-80E and it was decent enough!
Douk T8 Pro (7-Band Equalizer Preamp)
This is a fascinating one. It stands out for having a 7-band Equalizer. Also, it has both Balanced (XLR) and RCA Inputs and Outputs (just one set each). My unit is on loan from Douk. Again, this is an Opamp based Preamp (JRC2068D and N5532; see top pic for more detail), with Russian 6N1P buffer. Runs on 12V DC. Price is around RMB 650 (USD <100)
I don't have any balanced stuff here in SZ to try it out, but keep in mind that it can serve as an XLR to RCA convertor and vice versa.
I ran it first with the stock Russian 6N1P. Sound was surprisingly decent. Even then, I noticed that the sound is faster in transient than either 6N3P Preamps above. As I use my own SMPS PS with digital display, I noticed instantly that this preamp draws a much higher current than the others. At turn on, it transiently hits even 1.5A, but very instantly normalizes to just under 1A. Not surprising, as there are a total of >10 Opamps in the signal path alone. This is double the current of the 2 preamps above. With all the Equalizers flat (12 O'clock) sound was a shade plain, perhaps even betraying its opamp origin, if just a shade. So I proceeded to:
Equalizing The Equalizers are centered at 50, 125, 315, 750, 2K 6K, 16K Hz. I'm not at all a student of equalizers, so I don't even profess any knowledge about whether these are effective points, well chosen or not. I also don't know the slopes nor the +/- db offered. Just like how I dial in subwoofers, I think these should be used judiciously and with great restraint. As my system is fairly balanced and neutral, I felt no need to equalize at either end. Instead, I almost on impulse, and randomly, bumped up the 750, 2K and 6K to around 2 O'Clock. The idea was to raise the (upper) midrange a little. Well! It worked better than I thought! First, the slight paleness filled out. Any negative effect of Opamps was diminished. These settings worked for me, but for your system it might be otherwise.
Tube Rolling Unlike 6N2, where you have to use an adaptors to roll tubes, and unlike 6N3, where there are few substitutes, 6N1 has pin compatible direct substitutes. You can directly plug in 6DJ8 (family) and 6CG7. These are tubes that many people who play with modern stuff like Schiit have in their arsenal. I just happened to have brought some of these over for my BRZ amp tube rolling using 6N2 adaptors. 6DJ8 The Amperex Holland brings about a much greater refinement than the stock Russian 6N1. 6CG7 But my heart belongs to these. The Matsushita were a shade dry, but the GE proved just about perfect. Moist, but dynamic and refined. Now, where are my RCA Clear tops? Tube rolling effect is greater than equalizing. Some people would say that, though pin-compatible, these are not exact equivalents. But, why worry? This is all about equalizing, right? After I rolled in the 6CG7 I felt absolutely no desire to roll others and proceeded to compare:
vs 6N3 Preamps The Douk sounded so right that I totally forgot it has Opamps in it (especially when equalized). The low strung PJM didn't really sound transistory but in comparison was less three-dimensional, and smeared in terms of imaging. Even the all-tube ETA fell behind. By a good margin, with the transient sharpness, airiness and good tonal control, the Douk simply sounds more present, and involving, and by a good margin.
vs Douk E6 This article took a long time to write. I compared the participants multiple times, both with Russian tubes and with tube rolling. Now, with everything going on, I haven't fired up my Douk E6 in ages. Despite its quirkiness regular readers know how much I respect this little gem. Suffice to say, equipped with the GE 6CG7 the Douk T8 Pro did not loose too much ground. Best, it conveys the drama and narrative in the music as well. The E6 is for sure a little airier and luxuriating in the treble but not by as much as you think. That translates to great praise for the T8 Pro.
Suffice to say, lately I have been largely using the T8 Pro. I periodically rolled in the ETA and the PJM but I always revert back to the T8 Pro. That says a lot. I think I'd purchase my sample.
Thoughts
- 6N1P vs 6N3P Based on this limited experiment, I'd say it's more fun with the 6N1P, more rolling old stock possibilities!
- PJ Miaolai This is a pretty good Preamp, but not in the first tier. For its ridiculously low price, it can serve as a good switchboard, with 4 in and 2 out! AND, Headphone Output!
- Douk T8 Pro This is an excellent Preamp! Its Equalizers can even out its own mild deficiencies, and maybe your system's! I'm pretty sure I've not gotten to the bottom of it! For those who run both balanced and RCA, it's even more useful! Highly recommended! A niche product, but one that I heartily endorse.
PJ Miaolai. Engineer David of UMI said this is a poor layout not designed for the best sonic outcome. No matter. I wonder if the 2 Blue Caps are for tube coupling. 1.0uF 100V only.
Posts
This is just a gander. Looking at the douk, the blue electrolytic are the input caps. Blue films are the interstage coupling caps, parallelled . Differential inputs become single ended into the equaliser, then redivided into differential after the tubes.
ReplyDeleteThx for the input! That makes a lot of sense! If I ascertain which ones are the output caps I shall try to do some mods.
DeleteHave you tried to replace the Op Amps or do you feel there is no need because of the equalization?
ReplyDeleteNo. I feel it's pretty good with the old stock tubes and mild equalization. I don't usually dabble in opamps, as these items are not really my main interests, though I try to give them a good outing. Would be glad to hear about reader's experience too! I'm sure like tube rolling it's interesting.
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