Overview Sun Audio VT25 300B Philips AK601

Click pics to enlarge. Top, 300B amp built using Sun Audio VT25 kit with minor mods (see text below). The WE 274B and 300Bs are worth much more than the amp!!!!

Overview: Sun Audio

Glory: Western Electric
Letter from Hong Kong (24-1): Sleepless Night in HK

These days I go to Hong Kong to run errands perhaps every one or two weeks. To avoid crowds, I’d be on the Metro by 6:30 and be in HK around 8:30. I’d go for an early dim sum breakfast, then attend to things and return to Shenzhen well before the evening rush hour. I had largely avoided the Rush Hour all my life and that won’t change.

Last Wednesday, when 17 of us old Wah Yan Kowloon boys (Class of ‘72) gathered at the Cragengower Cricket Club (CCC) for dinner. This marked the first time I had dinner in Hong Kong in three years. Food was very good but even better were the wine brought over by two of the boys. I particularly enjoyed the Talbot Saint Julien (Second Growth).

Too late to go back to Shenzhen, so I got back to my old house around 11 pm and promptly fired up my SET amps. I went back and forth between my Sun Audio VT-25, my Sun Audio 300B (“mismatched” 5K transformers, using the VT-25 kit) and the Elekit 2A3 (TU-8230). I rummaged through my many boxes and dug out some precious tubes. Source was a lowest of the low end Philips AK-601 CDP. Preamp was the Melos 222 and loudspeakers the Ruark Crusader II.

Click pics to enlarge. Above, Station B Last Time. 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 CDP, 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. Note the Tile Floor.

I had written a little about the great sound of this Station B when I went back to the house last time (pic above, article here). Yet on this night the sound was even better, indeed exceptionally good; in fact, better than ever probably, and that goes back more than 20 years.  Yes, only flea power was on hand; yes, it was late and I was not listening very loud. But it was simply magical. As I wallowed in the splendor of the Triode, I asked why. I don’t have answers, but let me talk more first about some of the amps and tubes.

Overview: Sun Audio

I probably know more about Sun Audio than most people out there. I thank Hong Kong's Reference Audio for that. More than 20-25 years ago, they sold tons of Sun Audio kits in HK, at irresistible prices (like 1000 USD, including tubes). Many of my friends (like Hoi and I) bought more than one. They are fantastically finished, have a small footprint, easy to build and service and, most importantly, sound just fabulous. I know about all their models, and have heard most of them, and they haven't changed at all. I have myself (and helped others) converted some of them (like to 45). I have even met the father and son (here in my Guide to Akihabara). Unjustly, Sun Audio is not well known (or available) in the US, and that's just too bad. If you ask me, their amps sound better than those of most competitors. As the price of kits like Elekit has escalated to (for me) unreasonable level, I'd think Sun Audio offers a much better bang for the money. More below. The most iconic Sun Audio Amp is the 2A3. Indeed the basic circuit is there, and everything else are variants. Here is a bit of what I wrote in my DIY article:

• Example - Sun Audio 2A3/300B amplifier Back a decade ago, through my yahoo forum, I must have played a role in the popularization of Sun Audio kits, particularly in HK. I must say I have never met a Sun user who doesn't like his amp. But in the forum, where there are a lot of DIY people, including some well known figures, the very simple design did meet with various criticisms. Some of the people built kits by another kit maker (say kit B) and made every conceivable upgrades recommended by a respected electronic guru. A friend had a fully decked out kit B that used all manners of chokes and it went up against my Sun Audio. I personally feel, despite the simplicity, the Sun more than held its own. If not for my awkward position I'd call the Sun the outright winner. I wanted to support kit maker B and so did not really fully air my opinion. And what do I know about circuits to argue with the guru, who I also happen to like? As much as I respect electronic know-how, the experience taught me to keep an open ear, to say the least! My convictions were further strengthened when, over many years, I heard many decked out and not inexpensive DIY amps went up against the Sun amps. I am sorry to tell you all of them did not sound as musical. Now, I know fully well the Sun amps are not the ultimate in anything, and they are not cost-no-object designs to begin with, but they have continued to hold up amazingly well over the years. The designer had used his ears well and balanced things deftly to make simple yet engaging statements, thereby trumping much DIY grandiosity in the process. That is something called "art", which the majority of DIY people fail to understand.

That rings even more true today. In fact the electronic guru I mentioned had gone on to design for major companies. But my position holds. I'd think Sun Audio can compete with the best of them. The Wavac's (MD-300B and higher end EC) surely have more poise and drive, and the Verdier is no slouch, but the Sun Audio keeps up. What I'd love is to size up the Chinese APPL with this Gold Standard!

2A3 This is the foundation of Sun Audio. The output transformer has 2.5 and 3.5 ohm taps. This kit can be easily converted to use SE pentodes, tetrodes (even 45, my fav), etc. The 2A3 amp has long secured its place as the best. Not much can touch it. Second hand units trade quickly and price remains firm.

300B (LE) This is just a variant of the 2A3, using some simple mods for filament of 300B. Sound is under-rated. Very good, if you ask me. I used to have one of these (not the one I have now using mismatched VT25 kit) and imho it killed most of the competitors.

VT25 This one has a transformer that has 5K and 8K taps. The 8K is used for the VT25/10, and likely can also take the VT62/801A. Power rating is meager but it actually works quite well! My friend used it well to drive his Tannoy Black (here). For my experience see below.

Push Pull Amps Despite Gizmo's enthusiasm I don't like these. Totally dismissible compared with vintage. 

Preamps They seem rather simple. Never heard them.

As you can see from the above, I vouch for their SE amps, but not the rest.

Resource It's pretty amazing that Reference Audio has continued to sell Sun Audio products after almost 30 years! In fact their bilingual official website now is very informative of Sun Audio stuff. I direct you to the Sun 2A3 and you can go on there to view all other Sun models! Mind you, I think that's all fine with HK readers, but I don't think Reference Audio is authorized to sell US 120V products.

Listening Notes 

• Sun Audio VT25 Last time I listened to the thoriated RCA VT-25 and the formidable WE 274B and it was wonderful. This time, I listened to the WE VT-25 with the (lesser)WE 422A rectifier, and I think it was even better, mesmerizingly subtle and refined. No matter how you tube it, this is a fabulous amp that belies its ultra-low wattage (rated 1.3 watts, probably lower) if your loudspeaker is sensitive enough. I note that I can probably also use (thoriated) VT62/801A, and may try it next time.

• Sun Audio 300B This time (see top pic) I gave it the royal WE treatment and, boy oh boy! The beauty is beyond words. The very subtle articulation surpasses even that of the VT-25, though the latter was a little more yang. It made Until the End of the World, an album that I have listened to umpteenth time, sound like a new album. The pulse was sheerly riveting! Paradigm of Rhythm and Pace (PRaT)!

• Elekit 2A3 (TU-8230) After all that, the Elekit could only came in a distant third, even with old-stock Single Plate 2A3. BUT, it still has that subtle articulation that I like even without WE tubes. Which leads me to...

• Philips AK601 CDP As a basic sonic signature was retained whether WE was in the chain or not, I must credit this very humble CDP for the great sound on offer! This is an ultra low end CDP using CDM4 transport and 16-bit TDA-1543 with 4x Oversampling. And it has a captured generic red-white interconnect (I will upgrade it in due time). Regular readers will know I love the sound of this type of CDP (for a start, see this article).

• vs Shenzhen In a link earlier in the article, I made no bones that my HK setup is superior in sound to my SZ setup. The room, the equipment, they all make a difference. But I still am happy with the sound of my current SZ setup, which will be updated in a coming article (some new players).

I was so intoxicated by the sound that I listened till 3 am. Sleepless night indeed!

Schematic of Sun Audio VT-25 amp (from Reference Audio)

View from the Government Education Bureau in Kowloon Tong.

The right-most hill is the symbol of HK, the Lion Rock  

Kowloon Wah Yan, a Jesuit School

肉丝炒面，深水埗 大利

HK Staple, so-called Singapore Noodles！