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Integrated amplifier

Sophia Electric
91-03 300B

Manufacturer: SOPHIA ELECTRIC, Inc.
Price (when reviewed): 45 900 PLN



Provided for test by: HI-END DISTRIBUTION

SOPHIA ELECTRIC is a small family company with a seat in Vienna – but the American Vienna, Virginia. Run by Mr Richard Wugang, it is mostly known for excellent vacuum tubes, including the 300B. However, it also offers amplifiers that are based on these tubes, as well as loudspeakers. We are testing the company’s integrated amplifier based on the 300B tubes in the SET configuration.

here are names that we automatically associate with some type of a product. For example, Ancient Audio is associated with tube amplifiers, Takatsuki – with the 300B tubes, etc., while the former company’s first product were loudspeakers and Takatsuki also offers an amplifier. It is similar with the American SOPHIA ELECTRIC company. It was set up in 2001, offering the 300B “Mesh Plate” tubes, but already a year later it offered an amplifier that made use of them.

It was a design based on the legendary Western Electric No.91-A amplifier – the similarity of the names is no coincidence. It was a monophonic device designed at the end of the 1920s to be used in cinemas, based on 300A (output) and 310A (control) triodes. Sound in cinemas was a priority then, as the cinema was the most profitable branch of the entertainment industry. Loudspeakers and amplifiers used for the purpose were given special attention and a lot of money was invested in research, thanks to which we are dealing with high-quality audio today.

One of the special features of sound systems at that time was a combination of low-power amplifiers with high-sensitivity loudspeakers. The Western Electric amplifier that used the 300A tube, the predecessor of the 300B, offered 5-6 W of output power, so it needed loudspeakers offering sensitivity over 100 dB. Such an arrangement has its advantages and disadvantages. The former include low distortion (the lower loudspeaker sensitivity is, the taller they usually are) and a very high speed of response to an impulse – loudspeaker membranes almost do not move. When it comes to drawbacks, the ones that are mentioned most often are low linearity, limited frequency response and sensitivity to noise produced by amplifiers.


Last year we celebrated the eightieth anniversary of launching the 300B tube, the perhaps most famous amplifying triode in the history of audio. It offered higher power than its predecessor, the 300A and it was more linear. It was for the new tube that the design of the No.91-A amplifier was modified, becoming the basis for the first Sophia Electric amp. The modifications did not result from some crazy idea and they were not brought about by an impulse. The person behind the new design was Mr Dr. DWU, the father of Richard Wugang, the CEO of Sophia Electric. Mr Dr. DWU was in love with tubes and tube technology. He, as well as his son, who built his own amplifiers when he was 10 years old, owned a rich collection of “vintage” amplifiers, including a lot of Western Electric monoblocks.

Out of this love, the 300B tubes with the Sophia Electric logo were born, aiming to combine the “magic” of the sound of original tubes from the 1930s and 40s with the requirements of our times, i.e. lower distortion and broader frequency response. The same approach was used by the company in its transformers – as they are also made independently. They are based on EI, i.e. traditional core, they also use dividers made of paper similar to the paper that was used in WE amps. However, the material used for the core and the winding method are new developments. One of the unique features of the Sophia Electric transformers is their small size which helps to obtain broader frequency response (in this respect, they resemble transformers used by another American company – Manley).

The electric design reflects some of the best technologies from many years ago. So, there are: point-to-point assembly, coupling and power supply capacitors selected on the basis of listening, as well as a rigid cabinet. Apart from the abovementioned amplifier, Mr DWU was also inspired by RCA and Klangfilm company designs. However, his own designs are not a copy, but something that Jeff Day called “reinterpretation” in his review. When Mr Wugang’s father died in 2007, the know-how did not die, as he had recorded all his observations in the Green Book, Mr DWU’s compendium of knowledge. It is the source of ideas that, taken together, gave us the 91-03 300B amp.

| 91-03 300B

Tubes | The 91-03 300B is a stereophonic tube amplifier, operating in the SET mode (Single Ended Triode). On the input, it has a double 6SN7 triode. Half of it operates in the preamp, while the other half controls the output tube. There, in turn, is a directly heated 300B triode. In the standard version of the amplifier, the control tubes are Chinese NOS products, but at an additional price we can order matching Sophia Electric blue glass Grade A 6SN7 tubes.

Also when it comes to output tubes, these can be the classic basic Sophia Electric model – i.e. everything is fine, but at an additional price we will get the Royal Princess 300B tubes, i.e. the highest model made by the manufacturer, which, as we can read in company materials, is higher than both the mesh version made by the manufacturer, as well as the carbon version. The 5U4G/5Z3PAT power supply tubes are available in a Chinese NOS version. And there is one more version of the amplifier: Super quiet where noise and hum have been additionally minimized. We are testing the basic version, but with the Royal Princess 300B output tubes.


Sophia Electric engineers used all the knowledge they had gained in the past to build the new flagship tube – the Royal Princess 300B model. The manufacturer says that it retains the best advantages of both the Princess Mesh Plate and the Princess Carbon Plate 300B models. It is also supposed to guarantee sound similar to the original 300B Western Electric tubes, while being “many light years ahead of any 300B tube that has ever been made”, including both the Sophia Electric Princess Carbon Plate 300B, as well as the Princess Mesh Plate 300B – two models that have gained recognition all over the world.

On the outside, the Royal Princess 300B tubes look similar to the carbon Princess 300B version (they share the same glass bulb), but the design philosophy was completely different in both cases. Their inner construction and the materials used for production are also different.

Price: 5,950 PLN/pair

The name of the 91-03 model is a direct reference to the name of the Western Electric amp. This is a “middle” model manufactured by the company, belonging to the 03 series. In 01 series there are orthodoxically designed monoblocks, offering classic sound for this type of devices. The 05 series includes top-of-the-range solutions and the distillation of the best technologies and solutions that the company has to offer. The tested amplifier is, as Mr Wugang puts it, a 01 amp in the same cabinet with a preamp. Its sound is supposed to be a combination of classic Western Electric sound and the requirements set by contemporary audio, mostly regarding broad frequency response.

The look | It is a tube amplifier with a dual-mono tube power supply unit. It looks like a classic amplifier of this type, i.e. the tubes are located on the upper panel, behind them there are transformer casings, while at the front, on the low front panel, there are knobs. As for style, the device is close to amplifiers having a modern graphic design, if we consider QUAD devices to be almost identical replicas of amplifiers from the 1930s and 40s, and the products of the Polish company EGG-SHELL as a breath of modernity.

It is a design which makes us think of the 1970s with their functionality and almost laboratory-like “purity”. The cabinet is made of thick aluminum panels, silver on the top and at the bottom, and black on the horizontal elements. The transformer casings have been made in a similar way. There are two chromium-plated knobs on the front panel – one for volume control and one for the inputs. There are five inputs and their gold-plated RCA sockets are located on the rear panel. They are situated far from one another, so we can use any interconnects we like. Attention must be paid to the reverse (compared to what is currently commonly accepted) location of the left and the right channel – the right (red) channel is on top. A similar arrangement can be found in Mark Levinson’s preamps from the 1970s.

The output transformers are wound by the manufacturer, just like the power supply transformer and chokes in the PSU. The power supply unit is larger than stated in the specification, as the transformer has the power of 220 W. It has a double secondary winding for anode voltage. The inner cables are made of OFC copper. The power switch is located at the side, near the power outlet. It is a solid, accurately made device. I only missed descriptions on the rear panel – there is only a sticker there.


The amplifier was placed on the upper panel of the Finite Elemente Pagode Edition rack and in the audio path it replaced a two-piece system costing over 300,000 PLN, consisting of the tube Ayon Audio Spheris III preamp and the transistor Soulution 710 power amplifier. Signal was sent from the output of the SACD Ayon Audio CD-34 HF Edition (№ 1/50) player. Power was supplied using the Hijiri SM2R “Sound Matter” cable, while signal was sent to speakers with a NOS cable: American Insulated Wire Corporation WE16GA.

Recordings used for the test (a selec- tion)

  • Charlie Haden & Chris Anderson, None But The Lonely Heart, Naim naimcd022, CD (1997)
  • Nat ‘King’ Cole, Penthouse Serenade, Capitoll Jazz/EMI 94504, “Super Bit Mapping” CD (1952/1998)
  • Patricia Barber, Companion, Premonition Records/Mobile Fidelity Sound Lab UDSACD 2023, SACD/CD (1999/2003)
  • Peter Gabriel, So, Realworld/Virgin SAPGCD5, SACD/CD (1987/2003)
  • Ron Carter, Uptown Conversation, Embryo Records/Atlantic/Warner Music Japan MTCJ-6007, “Atlantic Original Collection | Vol.7”, CD (1970/2005)
  • The Oscar Peterson Trio, We Get Request, Verve/Lasting Impression Music LIM K2HD 032, K2HD Mastering, „24 Gold Direct-from-Master Edition UDM”, Master CD-R (1964/2009)

While testing the Sophia Electric amplifier, I was in the middle of my preparations to the Audio Video Show 2019 exhibition where I was planning to hold four different workshops (five meetings). One of the topics pertained to the role of the double bass and percussion in recordings. Thinking about that, I prepared a set of albums that I tested with an expert, Marcin Oleś. And I also used these albums to test the American amplifier. Perversion? 8 W with the Harbeth M40.1 and bass? You would be amazed how perfect it sounded!

Already the monophonic, classic recording of Nat ‘King’ Cole’s 1952 album Penthouse Serenade showed something that would later return with almost every recording and every album – amazing culture. It is sound that flows, fills the room with sound in an unaggressive way and without imposing itself. It creates large phantom images without bringing them closer. So, the leader’s piano was fantastic in its “presence”, about a meter behind the line connecting the loudspeakers, while the remaining instruments were heard behind it.

What is interesting, the percussion was not compressed into a narrow line, but – I do not know how this is possible, but that is the way I heard it – it came out at both sides of the piano, giving it solid background. The focus on the axis was brilliant and it was not about the presentation coming apart, resulting from uneven response of the left and right loudspeaker. It was a realistic illustration of the situation on stage where the piano is more audible and the percussion situated at the back sounds quieter, as it is played more quietly – for such recordings, musicians had to modify their ways of playing the instruments.

It is intensive sound in the sense that we get the impression that the whole energy contained in the recording is transmitted to our room without interference and obstacles. However, this is a completely different kind of energy than the one we get with a majority of other amplifiers – tube or transistor ones. Here it is energy that softly fills our room with sound. It does not scratch a place out for itself, but enters our world like silk.

That was well demonstrated by the next album – We Get Request by The Oscar Peterson Trio. This was energy! There was swing, rhythm and dynamics! It is because it is an incredibly rhythmical amplifier. Additionally, it offers great resolution – natural resolution in an ideal proportion with selectivity. So, I could hear a completely different kind of reverberation than on the previous album. However, most of the instruments and their proportions were surprisingly similar to those from Cole’s album.

The frequency response may be surprising – it is very broad. We read about it in company materials, Mr Wugang emphasizes this in every interview I have read, but it is different when you hear it from someone and different when you hear it yourself. It is an amp that does not pretend to be powerful, i.e. does not go particularly low on the bass, but it will be difficult for us to check this, unless we use electronically generated bass. With acoustic music, we will get a reliable picture of the double bass and percussion foot with their fullness, density and excellent decay.

It will be similar on the other side of the spectrum. The percussion plates were open, sonorous and had considerable weight. They were also soft and silky. They were, to be direct, incredibly natural. It is not the last word in selectivity, as the way they strike and the weight of the strike are not as well differentiated as with the best amplifiers that I have heard. However, if I remember correctly, the differences are not big at all and without a direct comparison they are negligible.

The way the tested amp builds 3D images in space is outstanding and one of the best I have ever heard in my system. We get large planes, there is breath and the sound stage has a lot of depth and width. However, in the first place, the instruments are perfectly correlated with reverberation. If it is a recording with closely located microphones, like in the two previous albums, everything is closer and it is larger. If the microphone is further away, like on Charlie Haden’s and Chris Anderson’s album None But The Lonely Heart, recorded using two microphones, the image is located further away.

It was incredible that the amplifier did not let the double bass and piano to be reduced, and it perfectly illustrated where these instruments were placed with respect to microphones. So, there was a lot of volume and the message was firm and powerful. At the same time, we instantly knew how different the type of recording we were dealing with was. After a moment, the “cognitive shock” resulting from a completely different perspective was gone and it was possible to listen to music without paying attention to technology – an incredibly important thing.

Sound was always in front of me, behind the line connecting the loudspeakers. Despite this, I had the impression that it was tangible and that it was an intimate meeting with the artist. This is what the best tube amplifiers (usually SET amps) sound like, perhaps due to the fact that the amplifier perfectly maintains the proportions between individual ranges and planes. Let us listen to Mercy Street from Peter Gabriel’s So album in order to hear what I mean.

The leader’s vocal is duplicated there. There is the main track, but right an octave below Gabriel’s soft quiet vocal was added to complete the whole recording. The additional vocal material was recorded early in the morning, right after Gabriel woke up – the aim was to obtain such an effect of sadness and melancholy. The Sophia Electric amp perfectly demonstrated that, wonderfully merging this into the fretless, five-string Yamaha bass guitar (BB5000) that was played by Larry Klein (bass guitar player, music producer, two Grammy awards winner, Joni Mitchell’s husband at that time).

I had no problem with how low the bass went, how filled it was or what energy it had. It was incredible how the 8 Watts filled my room with sound, with the Harbeth loudspeakers that are difficult to drive. I could not hear any overdrive or flattening of sound resulting from it. The vocals were not sharpened, either. It is not an amp that would make them more round, anyway.

The highest treble and its aliquots are shown in a silky pleasant way, but vocals are neutrally presented, i.e. without warming up or rounding the attack . If there are some more sibilants in the voice and they are slightly emphasized in the recording (it is so with Gabriel’s and Patricia Barber’s vocals), the amp will show it. So, it will work in a different way than a majority of amps with the 300B, as it will not “trim” anything. It is good, as it demonstrates how neutral (whatever we might say about it) the device we are dealing with is.

However, it must also be said that the tested amp is not the Alpha and Omega. It is, in the end, a very low power amplifier and, as a result, it is characterized by limited current efficiency. That is why more powerful amps, also tube ones, such as the Kondo OnGaku and Air Tight ATM-3211, present music with even greater swing and go lower on the bass. The reference system with a transistor amplifier was also more focused, showed 3D images of instruments more accurately, without losing sight of the whole event. However, none of these amps offered such silky smoothness (perhaps except for the OnGaku amp) and such naturalness as the Sophia Electric. Such is life.


While writing these words, I am listening to Ron Carter’s Uptown Conversations album. It is a multi-track recording typical for the 1970s, with low resolution and imperfect imaging. Despite this, the Sophia Electric amp dealt with the problems effortlessly. It showed everything I am talking about. It did not hide, back up or color anything. However, there was such truth in it and so much music that the recording technique became much less important. It was only important to the extent it created the music. The tested amplifier showed it exactly this way. If this is not high-end, I do not know what is… It is a beautiful example of how classic elements can be combined with modern solutions.

The look | The Sophia Electric 91-03 300B amplifier has a compact casing thanks to thick aluminum plates it is made from. Most information was already given in the introduction, so let us only add a few details. There is a red LED on the front panel indicating turned on power. Loudspeakers can be connected to one of two taps of output transformers – for 4 or 8 Ω impedance. Transformers are subjected to a copper “ageing” process (ageing consists in softening metal), as then they sound like a few decades old Western Electric transformers. The device stands on four plastic feet and there is no remote control.

The inside | The inside features the oldest known assembly technique: point-to-point, i.e. without the intermediation of a PCB. It is time-consuming and therefore expensive. It is also limited – every product sounds slightly different and in this way one cannot ensure 100% repeatability. However, it is thought that the technique yields the best results. Tube bases and other elements are attached to a glass fiber plate that is attached to the upper panel of the amp. This is to help reduce vibrations.

There are MKP coupling capacitors with the Sophia Electric logo in the path, made to order by some American manufacturer. There are also nice resistors, as well as vintage cathode capacitors. If someone wants, the capacitors used can be replaced with other (e.g. oil) ones for an additional price. Preamplifier tube bases and sub-assemblies are enclosed within metal screens in order to reduce noise and hum.

The design is symmetrical in the sense that each channel is identically built, including the power supply unit. There are as many as four chokes here – perhaps for the output and control tubes. Signal is supplied via handmade cables made of high purity OFC copper in Teflon pipes. Volume is regulated using a black Alps attenuator with a small engine; control was not made use of, however. It is the most classic classic :)

Technical specifications (according to the manufacturer)

Output power: 2 x 8 W/4 or 8 Ω
Input sensitivity: 450 mV
Input impedance: 100 kΩ
Frequency range: 12 Hz - 35 kHz (+/- 3 dB)
Residual noise/hum:
Super Quiet version: 0.9 mV | Standard version: 2 mV
Distortion: 0.18% (1 W/1 kHz)
Required break in time: 50-100 h


Reference system 2018

1) Loudspeakers: HARBETH M40.1 |REVIEW|
2) Line preamplifier: AYON AUDIO Spheris III Linestage |REVIEW|
3) Super Audio CD Player: AYON AUDIO CD-35 HF Edition No. 01/50 |REVIEW|
4) Stands (loudspeakers): ACOUSTIC REVIVE (custom) |ABOUT|
5) Power amplifier: SOULUTION 710
6) Loudspeaker filter: SPEC REAL-SOUND PROCESSOR RSP-AZ9EX (prototype) |REVIEW|
7) Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|


Analog interconnect SACD Player - Line preamplifier: SILTECH Triple Crown (1 m) |ABOUT|
Analog interconnect Line preamplifier - Power amplifier: ACOUSTIC REVIVE RCA-1.0 Absolute-FM (1 m) |REVIEW|
Speaker cable: SILTECH Triple Crown (2.5 m) |ABOUT|

AC Power

Power cable | Mains Power Distribution Block - SACD Player: SILTECH Triple Crown
Power (2 m) |ARTICLE|
Power cable | Mains Power Distribution Block - Line preamplifier - ACOUSTIC REVIVE
Power Reference Triple-C (2 m) |REVIEW|
Power cable | Mains Power Distribution Block - Power amplifier - ACROLINK Mexcel 7N-PC9500 |ARTICLE|
Power cable | Power Receptacle - Mains Power Distribution Block: ACROLINK Mexcel 7N-PC9500 (2 m) |ARTICLE|
Power Receptacle: Acoustic Revive RTP-4eu ULTIMATE |REVIEW|
Anti-vibration platform under Acoustic Revive RTP-4eu ULTIMATE: Asura QUALITY RECOVERY SYSTEM Level 1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RPC-1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RAS-14 Triple-C |REVIEW|
Passive filter EMI/RFI: VERICTUM Block |REVIEW|


Speaker stands: ACOUSTIC REVIVE (custom)
Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|
Anti-vibration platforms: ACOUSTIC REVIVE RAF-48H |ARTICLE|

  • HARMONIX TU-666M "BeauTone" MILLION MAESTRO 20th Anniversary Edition |REVIEW|


Phono preamplifier: Phono cartridges: Tonearm (12"): Reed 3P |REVIEW|

Clamp: PATHE WINGS Titanium PW-Ti 770 | Limited Edition

Record mats:


Headphone amplifier: AYON AUDIO HA-3 |REVIEW|

Headphones: Headphone Cables: Forza AudioWorks NOIR HYBRID HPC