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Positive Feedback ISSUE 53
Model 91-01 300B SET Amplifiers
as reviewed by Jeff Day
These Sophia Electric Model 91-01 300B mono amplifiers make you want to jump up out of your listening seat and dance naked before the musical gods, and I can promise you that it will effect your wife, mistress, girlfriend, boyfriend, or significant other in the same way, which means your life is about to become a lot more interesting. Yesirre, nude listening sessions are going to be part of your future with the Model 91-01 300B mono amplifiers from Sophia Electric, and you will not have to worry about having a Hi-Fi gut anymore because you'll be all fit and buff from all that dancing around and such. Go ahead and laugh, but I'm serious!
But I'm also getting ahead of myself, so let me rewind, and start at the beginning of this story to bring you up to temperature slowly (recommending a physical checkup with your Doctor at this point is probably prudent as well—you've been warned!).
Sophia Electric is a US-based company located in Vienna, Virginia, which designs, builds, and sells a full line of handcrafted high-performance vacuum tube Hi-Fi electronics, as well as several loudspeaker designs that are designed to work synergistically with them.
Richard Wugang is the President of Sophia Electric, and just so you know, Richard is one of us. That is to say, Richard has a consuming passion for great music and Hi-Fi, but unlike most of us, Richard came from a banking and finance career where he did quite well, which allowed him to dive into the deep end of the pool, so to speak, and to pursue a special shared dream to design, manufacture, and offer exotic high-end vacuum tube Hi-Fi gear to music lovers and Hi-Fi aficionados.
"Shared dream?" you ask. That's right, shared, as Richard's passion for audio comes by way of a family affair, as Richard's father also has a passion for all things audio, and in particular the study of vintage vacuum tubes and amplifiers. Richard's father encouraged him at an early age to get involved in the audio hobby, and Richard told me, "I started learning to build tube amplifier projects based on Western Electric circuits when I was 10 years old. I hand wound the transformers and punched the chassis for each project. By the time I was fifteen, I could redesign circuits freely with the tubes I had on hand, and I optimized the output transformers to match the new designs."
Richard's father, Dr. DWU, recorded his research results into why those vintage vacuum tubes and circuit designs produced such marvelous musical performance in meticulous detail into his green colored spiral notebook, or as I will call it, the 'Green Book': "Ten years ago, my father gave me his Green Book, where he recorded his research results into how those vintage designs achieved such sonic magic, and he asked me to help him bring his audio dreams into reality, and that is how Sophia Electric got started."
As you might imagine, I was quite curious about the results chronicled in Dr. DWU's top secret 'Green Book' that he gave to Richard. After all, how many people do you know that have chronicled a lifetime of research results into the aspects of vintage audio technology that are primarily responsible for the audio 'magic' that vintage gear seems to be so easily capable of?
As you would expect, the 'Green Book' is closely guarded 'intellectual property' so I didn't get to thumb through it, but I was able to wheedle a couple of basics out of Richard about how its results influence Sophia designs. Some of the important elements of the Green Book approach are things like using the best in vintage circuits, incorporating the best design elements of vintage transformers into modern high-performance transformers, the best vacuum tubes currently available, and to not be afraid to incorporate techniques and materials that came to light after the vintage period passed that can make that old vintage magic have a second coming (easy boys).
That Vintage Western Electric Black Magic
The SET aficionados among you already know that Western Electric circuits are legendary among the cognoscenti, even a kind of Holy Grail, and are considered a fount for transforming recorded signals into musical life. Some of you think I'm just talking about the rediscovery of Western Electric single ended triode circuits by the audio community back in the 1980s, but that's only part of the story. Western Electric circuits were adapted, or modified, for playing live music as well as recorded, and some of the greatest Fender guitar amplifier circuits from the 1950s can be traced back to licenses from Western Electric and ATandT (Western Electric – 1872 to1995, R.I.P – was the research and development arm of ATandT).
So Western Electric's circuits, designs, and innovations were used in signal amplification, like the Vitaphone that first brought sound to movies, or the electrical recording method used by record companies in the 1920s along with the Orthophonic phonograph that was used to play them back, or the Westrex optical sound technology, or the Westrex cutter system for recording stereophonic sound in a single-groove (thank you WE!), and Western Electric also licensed circuits, or aspects of their circuit designs, to be adapted for amplifying musical instruments for live music, such as Fender guitar amplifiers and others. From audio and movie sound, to cutter heads, to amplification for musical instruments, or just about any other signal to music application you can imagine, Western Electric was there. That's impressive.
Keep in mind that Richard has been designing circuits based on classic Western Electric circuits since he was 10 years old, which I also find impressive. So I think we can forgive Richard if he doesn't want to elaborate too much about how he has optimized those circuits around concepts gleaned from his own hard-won experience, and the observations recorded in his Dad's Green Book.
Richard told me, "The beauty of the WE 91-A circuit is its simplicity, however, the circuit needs a serious re-do to get the best performance …" with today's state-of-art modern loudspeakers, sources, and transformers.
For example, Richard told me that the original Western Electric 91-A amplifiers used WE 310A's as driver tubes that are now both excruciatingly expensive and hard to find (used WE 310A's go for about $500 a tube these days if you can even find them), making them a poor choice for a modern production amplifier with customers who want to keep their amplifiers running in tip-top shape for the long haul.
Richard also said that the Western Electric 91-A circuit needs modifications for other reasons as well, like addressing its lack of high-frequency extension. As good as that original WE circuit was through the mid-range, it did not offer much high frequency extension, so that needs to be addressed for the circuit to perform at its best in modern Hi-Fi systems.
The same thing goes for the original Western Electric transformers too, they're magic in the mid-range because they were originally designed for cinema use to amplify the voices of the actors, but they'd don't have good bass extension, which in high-performance loudspeakers that go very deep in frequency extension, like my Westminster Royal SEs, that just isn't going to allow the listener to hear what they're capable of.
Then there's the fact that the original WE 91-A circuit was designed to put out 5.6 watts per channel at 300V plate voltage and 60ma in plate current. The reason for the conservative power output was that Western Electric wanted an amplifier that was easy on tubes so a theater owner could put the amp in place and forget about it, knowing that it would reliably provide service for the next 30 years without issue, and the low stress on the ultra-reliable WE vacuum tubes provided that.
The original WE 9-A1 circuit was also very sensitive to local AC voltage differences, and that's acceptable for the USA market for which it was intended and tolerances were quite good in most places, but that's an issue that needs to be addressed for products that see worldwide distribution in today's world where the electrical grid can vary quite dramatically from country to country.
So Richard and his team at Sophia Electric totally redesigned the WE 91-A circuit for a new driver tube choice, the Sophia Electric 6SN7 ST, which was chosen for its linear performance and its ability to deliver enough voltage swing to drive a 300B tube with aplomb. The new SE circuit was also designed to be less sensitive to local AC voltage differences, which makes it possible for Sophia Electric to market its 91 style amplifiers in Europe as well as in the US, an important marketing consideration. The SE 91 style amplifiers also use much better output transformers to deliver better bass and high frequency extension to better match today's state-of-art systems.
So as a result, Sophia Electric Model 91-01 300B amplifiers have an optimized circuit that differs from early WE versions in order to maximize performance in modern Hi-Fi systems. So it is not a replica of the classic WE 91-A circuit, but rather it is Sophia's interpretation of the WE 91-A sound and music playing ability, but with new tube choices, and new transformer technology.
Richard told me: "Surprisingly the end result of the Sophia Electric 91-A style amplifier is that the vintage WE 91-A amplifiers and SE 91-01 amplifiers sound very similar, except that the SE 91-01 is also able to extend that sound to the frequency extremes. Both circuits have pursued the max voltage swing with minimum distortion from the driver stage. As a result of adapting the circuit to use the SE 6SN7 ST as the driver tube, the SE 91-01 amplifier can deliver 8 watts from a single ended design with zero global negative feedback. The original WE 91-A amplifiers only had 5.6 watts of output because they were operating at much lower plate voltage at 300VDC plate and 60ma in current. We feel the Sophia Electric Model 91-01 300B mono amplifiers are quite an accomplishment for us, as a pair of vintage WE 91-A amplifiers would command $50-$80,000 in Hong Kong and China. While the new production SE 91-01 has a wallet friendly price of $4000 with all of the vacuum tubes."
So, friends, here's my take on all of this: Many of the great discoveries that exist now, and those that will come into existence in the future, are the result of "standing on the shoulders of giants." This is what Richard and his Dad have done in their own pursuits with their SE 91 style 300B amplifiers. I also think it's really cool that Richard and Dr. DWU gave a respectful nod of the head to those giants of yore by naming their company Sophia Electric. Western Electric, Sophia Electric—get it?
There's also that Sophia part of Sophia Electric's name, the implications of which will be immediately recognizable to those who love learning and knowledge, as it is where our contemporary word 'philosophy' is derived from, as in philo-sophia, which quite literally means the love of wisdom. It's obvious that both Richard and Dr. DWU love wisdom, the wisdom of past ages encoded into those timeless Western Electric circuits, and the wisdom that is yet to be searched out and discovered, while standing on the shoulders of the giants of the past while looking to the future. So my friends, I think the approach to the design of the SE Model 91-01 is really, really, cool, and I just want to give a nod of respect towards Richard, Dr. DWU, and all those at Sophia Electric for what they've accomplished in the SE Model 91-01 300B amplifiers, man you guys rock!
Let's talk a little bit more about transformers: So while the classic Western Electric circuits are musical magic, they were designed with components in mind that can now be improved upon, like transformers, and so they can be optimized for those improved components to realize an even higher order of performance. So while that sophia, that love for wisdom, that led Richard and Dr. DWU deep into the study of those classic Western Electric circuits, also allowed them to recognize that the vintage transformers used in those circuits were responsible for a lot of the musical magic those circuits were capable of. That led them to listen to and study vintage Western Electric, UTC, and Acrosound transformers, which are considered among the best in vintage transformer designs. Dr. DWU and Richard came to the conclusion through listening tests that it was vintage transformers with 50 to 80 years of 'aging' on them that sounded the best, and that aging contributes a lot to the magic sound that vintage gear is capable of.
So the challenge for Richard and Dr. DWU in designing new transformers was to get the magic sound that the best vintage transformers had after 50 to 80 years of aging, yet to also improve upon what they might not have, like high 20Hz to 20KHz bandwidth, or low values of hum and noise. After all, those vintage transformers were designed when most music and film sound systems were restricted to between 40Hz and 60Hz on the bottom, and around 12KHz on top, so those vintage transformers were designed with that in mind so were limited in how well they could do at the 20:20 extremes or beyond. So despite the brilliance of those transformer designs, they can be improved upon for modern high bandwidth systems.
So transformers are the beating heart of an audio circuit, and the composition and structure of the transformer core is important, as is the composition and nature of the wire, and how the wire is wound onto the core, and the type of insulation and potting used matters too. So it shouldn't come as any surprise to those who have been around audio for a while, that everything you do in designing and manufacturing a transformer will affect its sound quality and its ability to play music.
Richard told me, "The WE 91-A circuit has been studied worldwide and can be well understood by those willing to put in the time. However, the real secret to the WE 91-A sound is in the output transformers. Output transformers make all the difference."
When Richard designs transformers he considers there to be two tiers of transformer design prowess:
"The first tier of design is to deliver the transformers' design specifications. This in itself is hard enough to accomplish for manufacturers worldwide. There are only a handful of people around the world who can deliver both quality bass extension and quality high frequency extension in a transformer design. Any experienced audiophile can hear the sonic difference between different brands of transformers, even if they have the same specifications. That is where the art and taste preferences of the designer affect the outcome of the final sound of the transformer."
"The second tier of transformer design is related to the difference that art and taste bring to the voicing process of the transformer design. So in this tier there is a competition for the best sound and musical performance from the transformers. In my designs I go for that vintage sonic flavor that only 50 to 80 years of aging can give a transformer. I want a sense of natural warmth, and a sound that makes my spirit happy when I listen to the music. I want superior detail, superior timbral textures, and without the sound being at all bright. I want the fresh and vivid colors inherent in the music to come through. I want the transformer be able to do the big swings in dynamics, to have speed, and to have low distortion. I want there to be a big sense of space around the instruments."
"A Sophia Electric transformer out of the box can have the best qualities of a vintage transformer that has been aged 50 to 80 years, but it'll be able to excel in other areas that no vintage transformer will ever be able to match. I do this by applying modern high-tech science through materials science, and through heat, cold, magnetic, and aging treatments that replicate the aging process and provide a vintage flavor. An analogy would be to make new production wine that tastes as good as a 50-year old specialty wine."
"Wire is important. As we all know, interconnect and speaker cables can make a sonic difference. If five feet of interconnect can make a difference, or 10 feet of speaker cable can make a difference, then 2000 feet of transformer magnet wire surely can make a huge difference! Surely, the secondary winding would make a huge difference in the output transformers! We have done a lot of research into transformer material choices; winding method optimization; special heat, cold, magnetic, simulated aging, and crystal alignment treatments applied to the transformers; to make our transformers really special in the way they sound."
The Light from Within
So what's left when you have the best in an amplifier circuit, and transformers that are designed to perfectly complement that circuit's performance, not to mention blow your mind? Well that would be picking the best vacuum tubes currently available for the circuit.
The vacuum tube complement that is provided with the Sophia Electric Model 91-01 300B mono amplifiers are the Sophia Electric Princess mesh plate 300B tubes (normal retail is $450 per pair), the rectifier tubes are vintage Chinese JAN grade 5Z3PA (normal retail is $40 per tube), and the stock driver tubes are Chinese 6SN7s.
The Sophia Electric Model 91-01 300B mono amplifiers that Richard provided for review are completely stock, except that Richard replaced the stock Chinese 6SN7 driver tubes wit the new Sophia Electric 6SN7 with the ST bottle shape that he is really excited about, and are available as an option, an option that he highly recommends as and upgrade from the stock tubes (retail for the SE 6SN7 ST is $100 per tube for Grade A, or $80 per tube for Grade B). I didn't have a spare set of Chinese 6SN7 tubes to compare to, but I can say the SE 6SN7 ST tubes Richard provided are stunning to look at with those gorgeous ST bottles, and if it were me I'd pay the extra $200 just to be able to look at them, however, Richard says they also offer a substantial improvement musically and sonically, so it sounds like a no-brainer decision all the way around.
So to cut to the chase, the Sophia Electric Model 91-01 300B mono amplifiers use a premium variation of the Western Electric 91-A circuit, custom SE transformers that just ooze cool factor and great sound, and some of the very best vacuum tubes that are currently available. So what do 300B monos with a superb circuit, exotic high-performance transformers, and some of the very best vacuum tubes available today sound like? Read on.
System and Synergy Stuff
All listening for this article was done using my System 1 that is optimized around my Tannoy Westminster Royal Special Edition (SE) loudspeakers. If you are not particularly familiar with single ended triode (SET) vacuum tube amplifiers, you might not know that these low-powered works of audio art (8 watts in the SE Model 91-01's case) require careful matching to high sensitivity speakers to perform at their full potential and to produce 'live' volume levels. If you match an SET amp to a loudspeaker that is too low in sensitivity the amplifier will not have enough power to adequately drive the loudspeaker to normal listening levels, and an SET amp's tonal characteristics can vary quite widely if it doesn't see a relatively stable speaker impedance. The Westminsters relatively high sensitivity of 99dB with 2.83 Volts at 1 meter and stable impedance make them a natural match to SET amplifiers of about 5 watts and up, and my West's turned out to be an extremely nice match with the Sophia Electric Model 91-01 300B mono amplifiers.
The review pair of Sophia Electric Model 91-01 300B monos did not come with any power cords, but as I understand it that was an oversight, and they normally ship with power cords. In my case the missing stock power cords doesn't really matter, as I generally ditch generic power cords the first chance I get and replace them with either the superb Sablon Audio Robusto power cords, or the equally superb Acoustic Revive Power Reference power cords, depending on which has the better synergy with the equipment I'm reviewing. The reason I change out power cords is both about the ultimate level of performance the component is capable of, and making sure that I have the most synergistic match possible to show the component under review in its best possible light. High-performance power cords can make a remarkable difference in the ultimate level of performance, and that's one of the things that I want to find out about a component under review—what is it really capable of in the best of circumstances? In the case of SE 91-01 that ultimate level of performance is quite impressive.
Speaking of synergy: I've been using the EMT TSD-15 phono cartridge (with Auditorium 23 step-up transformer) in combination with a Sablon Audio Robusto power cord on my reference Leben CS-660P power amplifier, which gets the best performance I have yet been able to realize out of it. It turned out though that the combination of EMT/A23 and Robusto just did not compliment the Sophia Electric Model 91-01 300B monos amps in the same sort of way, making them sound a little dull and lifeless overall, and weirdly, sounding a little screechy on the strings, which is pretty much the opposite of what I would have expected. Go figure.
However, when I put my Clearaudio Virtuoso Wood phono cartridge on the VPI Classic tonearm in place of the EMT, and used the Acoustic Revive Power Reference power cords to feed the juice to the Sophia Electric Model 91-01 300B monos in place of the Robustos—I was listening to the Nirvana Unplugged in New York LP at the time—it was one of those 'Wow!' synergy moments that just make you shake your head at the spectacular results. The sound really opened up with sparkle and life, became infused with tone color, and the amps made the music really swing with energy and presence! Who would have thought that would happen! Making sure your associated equipment is the best possible match is essential to getting the best from any piece of equipment of system. It's not always true that what's good for the goose is good for the gander, and in this case what was best for the CS660P was completely different than what was best for the SE 91-01.
The combination of Sophia Electric Model 91-01 300B monos, the Acoustic Revive power cords, and the Virtuoso Wood cartridge ran circles around my Leben CS-660P stereo amplifier, Robusto power cord, and EMT combination in musical terms—at about half the latter's cost—making the amps really sing and swing, and making me want to jump up out of my seat and join the action on the 'dance' floor!
That is the first time in my experience than any amplifier has so clearly shown the Leben its heels in terms of musical expressiveness. One of the things I love about the Leben CS660P, and the reason it has maintained center stage in my system for such a long time, is its ability to make the music come alive. It's a great amplifier. The Leben CS660P has met its match and then some in musicality with the Sophia Electric Model 91-01 300B monos, and that's really something, because the CS660P has done the same musically to nearly every other amp it's gone up against, so you can imagine that that really got my attention, as well as elicited my admiration.
I'm listening to my copy of an old Analogue Productions test pressing of Bill Evans Trio's Waltz for Debbie on the Sophia Electric Model 91-01 300B monos right now as I write this, and I have to say the resulting musicality and sonics is just blowing my mind. First of all, I think the timbre of the instruments is completely believable, with an effervescent presence that is full of color and emotion that just has to be heard in person to be fully appreciated. Richard is not just engaging in good marketing when says these SE 91-01 amps are something special—they are. The Trio's drum kit sounds so utterly natural though the Sophia Electric Model 91-01 300B monos that it is really quite amazing, I don't think I've ever heard sticks on cymbals sound so correct timbrally, and so utterly mesmerizing. Same thing with Bill's piano, which elegantly portrays the beauty of the music in unsurpassed style through the Model 91-01 300B monos.
Bassist Scott LaFaro's playing is just amazing on Waltz for Debbie, and you really get the sense of musical virtuosity he displayed while recording this album, which was shortly before his death in a car accident. I know this is going to sound really nerdy, but the pitch definition and articulation of the individual notes on Scott's bass is just so amazing with the Model 91-01. Not only that, the Model 91-01 is better at reproducing a natural sounding bass line, in the way the bass notes wash over my body in a tangible and physical way, than any amp I've ever come across. What Richard has done in designing the transformers of the SE 91-01really pays huge dividends in the bass region, and the SE 91-01 betters any other amp I've heard in the way it handles bass.
The stellar bass performance of the SE 91-01 really made me stop and think that there's a lot that can be attributed to a contribution from that intriguing transformer design, and that transformer may be a lot of the why behind why this amp plays music so well and sounds so good. I'm not sure I can really put my finger on it in any specific quantitative way yet that I can articulate, but the SE 91-01 just delivers a musical experience in unparalleled fashion, and sounds fantastic while doing it, and very much in the same way that Richard says he voices the trannies in that second tier of transformer design.
Part of the magic of the SE 91-01 is the way it allows the music to flow along in tempo in such a liquid and utterly natural way, and the way the dynamics interplay with that temporal flow to really make the melody lines come alive. I think that aspect of its performance plays a large role in what makes the SE 91-01 so absolutely captivating in its ability to draw me deeply into the feeling of the music.
This is a big deal. For music lovers and audio nuts alike. The Sophia Electric Model 91-01 300B monos have a rare ability to amplify my emotional connection to the music, in a way that I rarely encounter in an audio device, and that only my Tannoy Westminster Royal SEs seem to do as easily (and in an even greater measure—you do get what you pay for in the West's). Once heard, once felt, this main-lined, amplified, emotional connection to the music is very, very, addictive, and the SE 91-01 300B monos possess that ability in spades.
The SE 91-01 really delivers on the sonic side of recordings as well, and it projects a huge billowing soundspace that fills my room from top to bottom, side to side, and front to back (it is an indicator of how effective the SE 91-01 is in the very deepest end of the bottom octave where the movement of really low frequency air in a room gives what people refer to as a 'sense of space').
In fact, it is with the SE 91-01 that I first noticed an amazing ability that my Westminster Royal SE loudspeakers are capable of, which is to energize and 'light up' a room with the music in an extremely visceral way, so visceral that you can feel the music sound waves physically wash over and interact with your body. This 'supercharger' effect that the SE 91-01 brings to my Westminsters kicks in at live music-like levels beginning around 90dB, and it'll unhinge you from your normal perceptions about what the high-fidelity reproduction of music is all about.
My Westminsters, with the SE 91-01 mono amps in place, well it's like the emotional connection to the music goes through a step-function around 92dB or so that just supercharges the listening space, immersing me into a tangible, visceral, musical experience that just makes me want to jump out of my seat and get my ya-ya's out. Only a dead man could not respond to that level of stimulus!
Listening to Lucinda Williams' World Without Tears showed that the SE 91-01 monos throw an extremely deep and wide soundstage, with solid images portrayed in natural three-dimensional sizes, which also emerge in impressive clarity from a very black background of the recorded acoustic. The interesting thing in the way the soundstage is presented is that it seems that there is infinitely deep layering in how images are portrayed in the dimensions of the soundstage, and there's a natural reverb that surrounds the musicians in a positively surreal way that adds to the music's feel in a way that I never seem to get tired of. Notes seem to decay infinitely off into the reaches of the soundstage and soundspace, giving a sense of richness and beauty, which is unsurpassed in its ability to engage me as a listener. Man, these SE 91-01 300B monos are positively intoxicating set up as they are in my system with the Westminsters. Fuck!
I've enjoyed a lot of really, really, good audio amplification in my days, and from the best vacuum tube Hi-Fi designers in the world: single ended triodes with 45 tubes, 2A3 tubes, 300B tubes, 300B tubes interstage coupled to 845 tubes, and on and on; single ended pentode amps, hybrid amps, push-pull amps, solid-state amps, you name it, but I've never enjoyed the way an amplifier played music in my home like I've enjoyed this relatively inexpensive ($3500 a pair without tubes) Sophia Electric Model 91-01 300B amplifier design from Richard Wugang and his father Dr. DWU.
The Sophia Electric Model 91-01 300B mono amps make me get excited about the music coming through the speakers, they make me happy, and they make me want to jump up out of my listening position and dance about, or grab my guitar and play along, or in other words, to behave like a complete moonstruck musical lunatic. Nothing else has made the music and me come so convincingly alive in my home.
The Sophia Electric Model 91-01 300B mono amps are music lover amps, and they play blues, jazz, rock, pop, country, classical, and anything else you care to listen to with equal aplomb. They make you want to tap your foot to the music, or even better jump up out of your seat and pull your girlfriend into your arms while you waltz around the room dancing the night away. They'll make all your appropriate body parts hard as a rock, and you'll probably finish your waltzing around by flinging off all your clothes. Really. So be really careful who you invite to your listening sessions, it'll suddenly matter a lot.
The Sophia Electric Model 91-01 300B mono amps are audiophile dream amps, they have great sonics top to bottom, bass articulation that is the best I've heard, and the SE 91-01 nails all of the nerdy audiophile things like soundstaging, imaging, sense of space, and transparency in such a beguiling way that even music lovers that don't give a rat's ass about audiophile-type sonics will appreciate its prowess.
I recommend these amps heartily, and I'd give them my normal 'two thumbs up' endorsement, but that just wouldn't capture what these Sophia Electric Model 91-01 300B mono amps are capable of, so I've invented a new rating, the 'two hard nipples up' recommendation, which is the highest award I've given out to date.
In all seriousness, I haven't had this much fun reviewing and writing about a piece of Hi-Fi gear in a long time, and I'd like to acknowledge Richard Wugang and his father Dr. DWU for creating such a musically satisfying piece of Hi-Fi gear, and for offering it for sale at such an accommodating price. My hat is off to you, Richard, Dr. DWU, and all of you at Sophia Electric—very nicely done! Jeff Day
Price: $3500 USD without vacuum tubes, $4000 USD with full set of vacuum tubes, and $4200 as reviewed with the optional premium SE 6SN7 ST vacuum tubes.
Web address for Sophia Electric: http://www.sophiaelectric.com