13 February, 2024

UMI 1:1 Sun Audio 300B VT25 ICL

Click pics to enlarge. Not exactly on this occasion but close enough. Station B in front. Center, Philips AK601 CDP and Melos 222 Preamp below Sun Audio VT25 and DIY 45 amps. Left, from top, Micromega Duo transport, Micromega Solo, Elekit 8230 2A3 amp, Philips cheapo CD-771, Micromega Duo Pro DAC, PS of Melos 222 and Bryston 4B. To the right, note the Ruark Crusader II in front of the B&W Matrix 801 Mk II. Note the "wall" on the right side was a partition using steel cabinets. In the back (actually near the entrance) is Station A. CDPs in use are the Revox 221 and Pioneer T-07A, second and third from top, below which is the MFA Magus B Preamp. Amp usually a Rotel 870BX.

Letter from Hong Kong (24-6): The Longest Days, Part III

Written in Shenzhen

Part I
our gathering on Jan 28th in Chaiwan
Part IIthe next day, starting with the amazing den of Taimonsing. 

January 29, chez moi to finish
After being cooped up in the RCA Warehouse of Taimonsing, we had a late lunch. Then the 3 of us headed back to my old place in Pat Heung. Now you know why I fired up all my amps late the night before - in preparation for their visits! I planned out a program for them. Equipment was more or less as before (Station B described here; see Top Pic for Station A).

Program/Station A For a starter, I first fired up the B&W 801 Matrix Mk II. CDP was the Revox 221. Preamp MFA Magus B to the Rotel 870BX. I played mostly Until the End of the World. We didn't listen to this for very long as it's not the main program...

...then, after Program B finished, icefox the taskmaster asked for the Rotel amp to be replaced by Bryston 4B, which we did. Fortunately I was able to produce 2 XLR to RCA adaptors for use (no RCA inputs; there are actually a pair of professional TRX female sockets which I presume would take 1/4" phono plugs). With a lot more power than Rotel, the sound was drastically different, much fuller but less clean, the Rotel being faster in bass transients. But, as the 801 loves current, overall this was for sure an improvement. The Bryston had not been run for a long time, and it was probably a little murkier than when optimal, and there were occasional small popping noises...

...That was not all: see the UMI section below...

Program/Station B We spent the bulk of the time here. The Ruark Crusader II was used. CDP was the lowly Philips AK601 (CDM4/TDA1543). Preamp Melos 222. The program was to let them hear 2 Sun Audio amps, the 300B and VT-25, and an ICL/Softone 300B. Below you will find the reasons why I programmed it so.

Sun Audio 300B As mentioned before, this was built not on the 2A3/300B kit (2.5 and 3.5K taps) but on the Sun VT-25 kit, using the 5K ohm tap of the output trannies, so a "mismatched" amp of less than usual power (say between 4-5 watts). 6SN7's are a pair of old RCA's. As before, the 300B's and 274B are all 50's WE. The reasoning was to have them hear WE tubes. They have heard a lot, more than I (especially icefox) but not so often outside WE equipment or in humble SE amps. To my ears, this amp has the most WE qualities, including that elusive 撩撩吓 feeling. Many of the tracks on Until the End of the World have quite a bit of electronic ambient sound, swooshing and undulating. The effect is much enhanced in the amp. icefox incidentally might have found some of it a little "hea" (Cantonese for relaxed).

Sun Audio VT25  6SN7's are a pair of old suspended filament GE's. We heard first the white based WE VT25's with the WE 422A rectifier. The idea is also to hear WE tubes, albeit less famous ones (in particular, the 422A is much less regarded than the 274B). To my ears, sound was good (though some clipping is inevitable), but definitely less subtle and more yang than the 300B. And of course, sometimes the amp shows some clipping (1.x wpc)...We later changed to 274B and the sound improved markedly!

ICL/Softone 300B (here) I've always been an ICL/Softone fan. Very good designs for very sensible money, even now. The idea is to compare the WE equipped Sun Audio 300B amp with one using common tubes. The 6SJ7 (essentially a 6J7 without top cap) here is old stock glass GT with metal bass. 300B's a pair of old Shuguang's. Note that in its use of tubes this amp has a shade of the WE91A in it (though it is thoroughly modernized, with things like constant current source). Humble tubes. Sound is quite good, but modern, and certainly more powerful than the Sun.

UMI 1:1 Transformer (here and here) Surprise! I brought this one over from Shenzhen just for this occasion. The effect was unbelievable!
  • Inserted between CDP and Preamp It immediately improved the performance - across the board. Wider soundstage and better dynamics. It helped to bring the Sun VT25 closer to the 300B, but what was truly amazing to me was that, when used on the ICL, it kind of brought the modern amp (with modern tubes) at least a little bit closer to the old Sun with WE tubes. The ICL amp suddenly became less a straight-shooter and a little more suave!
  • In Station A Again, inserted between the Revox CDP and MFA Preamp, the sound took an unbelievable turn for the better. Pushed out envelope. Much cleaner and more dynamic! We played the Burmester CD2 (long oop; pirated on TB) and it was just fab! Taimonsing rated this one as the greatest improvement.
  • I gave the UMI to Taimonsing to make the rounds among the circle as I want more opinions. I'm looking forward to the feedbacks! U shall read more in this blog in due time!
  • WE 274B All agreed that this tube makes the most difference. In fact, although it's very expensive, the 274B in the VT25 amp gets my vote for the "best value" WE. Although the 274B is subtle, sinuous and tactile in its upper reaches it's amazingly powerful in the lower reaches. In fact, the way it fills out the lower end may be a character trait (I think Taimonsing will agree with me). If there is just one WE tube you should get, this is it.
  • WE 300B Personally, I think the real WE 300B is just a phenomenal tube. For me, its sophistication is way over any modern replicas. But, as mentioned above, the 274B is even better entry into the magic of WE. It's the essential portal.
  • SET? Now, you may not know that both my guests, Taimonsing and icefox, are not SET fans! In fact, at their dens, you shall not find any SET amps! All PP amps! Well, for the SET amps I demonstrated on this occasion, their comments are fascinating. "...don't sound like the usual SET amps we have heard..." I take that as a compliment! Yes, indeed, many SET amps are just way too lean and meager, but they are not for me.
  • Sun Audio Tamura Another note here on Sun Audio and Tamura transformers. If you ask me, I don't think I can easily find SET amps better than Sun Audio at any price. They are just superb value for money, and its a pity that they are so low-keyed and invisible in the US market. Mind you, for this round, I also screened Elekit 2A3 and my DIY 45 Amp (WE412 driver, Tango trannies), but I did not offer them for tastings as I thought their sounds would not be exactly what my guests were looking for.
Pics of the Food the Night before

1 comment:

  1. I think Sun Audio is about to take off in the States. Go search devonjas on youtube and instagram. He's the posterboy now for horns, tubes, vinyl, diy and vintage audio. Stock up if you haven't already :)