Click pics to enlarge. The left-most red caps are the output coupling caps.
Review: Eastern Transmission Audio 6N3 Preamp, Part I
Letter from Shenzhen (23-3): Second Spring
Note: 12/4/23: Due to the recent Failure of the Volume Pot, this Preamp is now not recommended!
Part II, on Mods (Cap and Cable change) had been published. Revelatory!
Part III, however, covers a serious failure of the volume pot. Highly annoying!
Part IV, on JAN GE 5670 tubes and more.
Now, the story of this Preamp is kinda interesting, with a major twist that involved Cable Change. The Cables involved were detailed in my last article (use link, or just roll down).
Seller I have noticed this seller for a long time. The offerings are classic in looks and interesting electronically. The logo says Eastern Transmission Audio (ETA from now on). I was actually primarily interested in one of their more expensive preamp offerings, the one using the unusual 3A5 direct-heated triode (one great-value option is packaged with an exceptionally interesting solid state 1969 Class-A amp; during the winter I almost hit the button, but now it’s spring already...). I decided to test out this very low-priced offering first. As I have a pair of brand-new Russian 6H(N)3 from another device, I bought it without tubes for RMB 255.
About The Heart of the Preamp is the circuit board (only amplification). For those who like to DIY, they can just buy the circuit board for less money than a good beer. The 2x 6N3 (double triode) are used in an SRPP configuration. There is an upgrade option, which replaces the 2x 0.33 uF, 400V, Rifa caps with upmarket Mundorf’s. I stuck with the basic version. The board is connected to a very basic solid state PS. There is only one input and one output, and a very small volume knob.
Sound and Issues When I first slotted it into my regular system (in lieu of the 6J4/6P6P Preamp and using the BRZ FU-50 amp), I was immediately shocked by the sound. The gain is even higher than the regular 6P6P Preamp, not surprising given that it’s SRPP. The Gain is such that it would be unusable for a lot of people. But, as I use SET amps and they all have a volume knob, I dialed down the volume of the BRZ amp (yes, if not maxed, that changes the impedance a little) and that helped. The sound was a bit on the aggressive side and a little lean, not unusual for a Russian double-triode. After much run-in, it smoothed out a little but still sounded more one-dimensional and I missed the richness of my 6P6P Preamp.
I removed it from the system and re-installed the 6P6P Preamp and lived happily with the system for quite a while. I opened the ETA and contemplated mods. Yes, I could change out the caps with Oil Caps (my preference is for the Russian ones, though they are a little too pricey now). Maybe the signal wires. There is not much room for a larger volume pot. I left it opened and put it in a carton box under the table.
Sometime later I discovered the Belden 8451 (see Cable article link on top). The sound is similar to the Canare L-2B2AT, but a little warmer. After comparisons, I changed out the Canare one-by-one, and the system became completely cabled with Belden. I don’t want you to misunderstand, the system did not sound that different than before. Whatever extra warmth was very subtle, but it benefited the BRZ FU-50's slight inherent leanness.
Recently, not sure what’s the next step, I put back the ETA’s bottom plate. I said to myself, what the heck, let me listen to it once more before modding it. So, I slotted it back into the system. Holy! For the second time, I was shocked by what I heard.
Of course, the Gain problem is exactly what it had been before, just that it has become less annoying. The tonal quality with the Russian tubes is still slightly on the lean side, but no longer somewhat frayed at the edges. Images are more solid. That it is highly listenable is shown by the fact that violin music, especially baroque violin without vibrato, has become highly sophisticated. This is aided considerably by the superb rhythm and pace. Compared to the 6P6P Preamp, it shows a faster transient, a leaner but tactile bass, at least as much resolution, more rhythmically alert and perhaps slightly more clarity, and all this from what is basically a stock tube.
What happened? I had to really scrutinize this question. Obviously, the synergy with Belden 8451 contributed significantly. But I think the nature of the 6P6P preamp is also a factor: its sweeter and likely less dynamic nature makes less of the difference between Canare and Belden. These two cables are like my two hands - I know them so well. At least so I thought, but now I know even more.
It’s been almost one month since the ETA went back in, and I feel no compulsion at all to change it out. For the measly sum, it has allowed me to learn more about my system. The funny thing is, 2 days ago, I re-opened up the 6P6P Preamp and studied for ways to modify it! It shall take some work but is on the agenda.
(added 2/20/23) Here is an anecdote that serves as a cautionary tale. Just yesterday I had an accidental discovery. One channel of one pair of 8451 went out and I discovered at one end the + was not even soldered (such was my skill and haste!). Miracle that it had played by just sheer minimal contact (well tugged into the trough) for so long! I swapped in a pair of Canare and, guess what? Before this I was puzzled that I was lukewarm to Amanda Beyer's new Biber album (Harmonia Mundi). Puzzled because she and her ensemble Gli Incogniti have long been favorites of mine. Today, I re-listened and had a totally positive experience! It's more rhythmically sophisticated now. So, cabling makes a difference, and titration is complicated sometimes by different effects on different musical material. There is no perfection, but perhaps it's not a good idea to use just one type of cable throughout. Such are the vagaries of cable swaps!
Tube Rolling Haven’t done any so far. The most obvious would be the 5670, which are not expensive. If you really want to splurge, you can use WE2C51/396A. For starter, I’d recommend the Russian 6H(N)3 rather than the Chinese 6N3. Although the latter is very good, and smoother, I’m confident the Russian one is a fine tube and it’s sold by others on TB for as low as RMB 10 each (you have to put up with running them in). At some point, I shall get some 5670.
A Word on SRPP As PP implies, it works the tube hard and some say may shorten tube life. SRPP usually has high gain, which goes to say that it has drive, but could be overdone for many systems. SRPP has long been favored by the Japanese (likely my Wavac PR -X2) and the Chinese seem to like it too. Westerners use SRPP less. There are a few other 6N3 SRPP preamps on TB. The minimalist one from Hubei that sells for RMB 189 tempted me, as it also uses a tube rectifier; but then there are just too many interesting things on TB (including the same seller’s 6J1/6P1 transformer output headphone amp/preamp) and one cannot have them all.
Is this for you? The VERY HIGH Gain is the question you have to answer. If you are a cellphone or BT guy whose source output is on the puny side, it may work well. If you are a regular audiophile with a decent system though it will take work to integrate it. If your amp has no volume knob, your options are limited. The ETA likely is very revealing (and demanding) of cables. The big question of gain aside, I’d think it is much more suitable for warmer systems than leaner ones.
Nothing is perfect, right? Now I have not one but two imperfect but lovable Preamps. Now, where’s my perfect preamp? Or, for that matter, perfect cable?
Tube Rolling Haven’t done any so far. The most obvious would be the 5670, which are not expensive. If you really want to splurge, you can use WE2C51/396A. For starter, I’d recommend the Russian 6H(N)3 rather than the Chinese 6N3. Although the latter is very good, and smoother, I’m confident the Russian one is a fine tube and it’s sold by others on TB for as low as RMB 10 each (you have to put up with running them in). At some point, I shall get some 5670.
A Word on SRPP As PP implies, it works the tube hard and some say may shorten tube life. SRPP usually has high gain, which goes to say that it has drive, but could be overdone for many systems. SRPP has long been favored by the Japanese (likely my Wavac PR -X2) and the Chinese seem to like it too. Westerners use SRPP less. There are a few other 6N3 SRPP preamps on TB. The minimalist one from Hubei that sells for RMB 189 tempted me, as it also uses a tube rectifier; but then there are just too many interesting things on TB (including the same seller’s 6J1/6P1 transformer output headphone amp/preamp) and one cannot have them all.
Is this for you? The VERY HIGH Gain is the question you have to answer. If you are a cellphone or BT guy whose source output is on the puny side, it may work well. If you are a regular audiophile with a decent system though it will take work to integrate it. If your amp has no volume knob, your options are limited. The ETA likely is very revealing (and demanding) of cables. The big question of gain aside, I’d think it is much more suitable for warmer systems than leaner ones.
Nothing is perfect, right? Now I have not one but two imperfect but lovable Preamps. Now, where’s my perfect preamp? Or, for that matter, perfect cable?
Posts
No comments:
Post a Comment