Q-tron Audio PA12B 2x25W Push-Pull Tube OTL Power Amplifier

Q-tron's OTL (Output Transformer Less) amplifiers provide clearer and more expansive sound quality compared to other tube amplifiers. By eliminating the output transformer required by ordinary tube amplifiers, it avoids the distortion and frequency response limitations caused by transformers and improves the clarity and response of sound. In particular, the Futterman circuitry is uniquely designed to achieve low impedance without the use of a transformer by configuring the output stage in a push-pull arrangement, resulting in a low output impedance and excellent balance. In addition, it features active noise cancellation technology to reduce noise to less than 100 dBA and a design that achieves very low distortion without excessive feedback. It has also proven to be reliable and have a long service life due to the minimal use of vacuum tubes. All components are designed and manufactured in Sweden and use high-quality components to ensure high performance over time.

Thanks to its unique driver circuitry, distortion is reduced to one-tenth that of other OTL amplifiers, and the PA12 is an OTL amplifier with two 6C33C tubes per channel. This unique driver circuit allows for an output of 25W. Even at an output of 10W, the distortion rate is less than 0.1%, which is very good for a tube amplifier. In addition, the distortion rate at 1W is even lower at 0.01%, and the active noise reduction technology keeps hum and noise very low.

The amplifier is mostly built on a large PCB, but uses point-to-point (PtP) technology for critical components. Ceramic solder supports are used that withstand 5 kV, and the chassis is made of 10 mm thick aluminum, which provides excellent mechanical stability and completely eliminates noise caused by vibrations.

The Q-tron PA-12 is a tube amplifier with an innovative push-pull design that redefines the possibilities of OTL amplifiers. In addition to the out-of-phase Futterman circuit, it uses a unique distortion and noise suppression circuit to achieve a pure and transparent sound that has never been seen before. It offers sound quality comparable to Class A amplifiers and performs beyond that very realm.
The appeal of the PA-12 lies in its outstanding texture purity and rich tone. Bringing out the essence of the 6C33C power triode, the high frequencies sparkle with life-filled clarity, and the low frequencies are powerfully expressed while maintaining extremely precise pitch control. Unlike traditional tube amplifiers, it avoids the problem of crossover distortion and provides a deep sound field and a three-dimensional sound image.
Another noteworthy aspect of the PA-12 is its speed of response to transients and the delicacy of its high frequencies. With no DC-blocking capacitors in the signal path, natural, organic details are reproduced in a perfectly controlled manner. This also makes the bus lines very clear and conveyed with a great sense of definition. It captures every minute nuance of music and resolves every detail of any recording, providing a technically superior listening experience that impresses the listener.
The PA-12 is a true reference-grade amplifier with a very low noise floor and extremely accurate reproduction of low-level detail. It captures the essence of the music, achieves a sound with excellent clarity and clarity, and eliminates unnecessary secondary and tertiary harmonic distortion.
For those who want the sonic purity of a tube amp, but with the same clarity and resolution as the best solid-state designs, the Q-tron PA-12 is definitely a top-tier choice. If the 25W/ch output is the right system, this amplifier is a game changer, unleashing the true potential of OTL technology to deliver the musicality and precision that your audio files demand. Highly recommended for anyone who wants to take their listening experience to a new level. *『Enjoy The Music.

The machine consists of 11 vacuum tubes. 6H6Pi x2, 6H2n-EB x5, and 6C33C x4. The miniature tubes are generally spheres close to 12BH7A and 12AX7. The output tube was originally designed for regulators and is impressively large. It has three horns on its head. When the power switch on the front panel is pressed, after 1.5 seconds, a light click of the relay is heard, and the current of the large toroidal transformer slowly rises. After 90 seconds, a second click is heard and the plate voltage is applied. After another 45 seconds, the short circuit of the speaker is released, and you can listen to music. Only then does the edge of the switch light up green. It also monitors DC leaks to protect important speakers. Note that if the power is turned on without connecting the speakers, the protection circuit will work. Originally, the 6C33C is a sphere that takes 10 minutes to stabilize due to specifications, so it will take more than 30 minutes for the sound to stabilize. The sound I heard was amazing. Whether it's classical or jazz, the sense of realism is amazing. No matter what kind of sound is heard, it is really stable even in transient areas. The swelling of the sound in the mid and low frequencies is moderate and pleasant, and you can feel the spaciousness. I was also impressed by the sound of plucking difficult guitars and shamisen, as well as the high frequencies of the trumpet. This may be due to the fact that the rise time is 0.5 microseconds.

The sound is precise, but I think it's not a monitor-like sound like you hear in a professional studio, but a sound that allows you to enjoy music. The one I used for the audition was Altec's Valencia, which has a high efficiency of 100 dB. I've played it with a number of amps, including the Yamaha B1 and the Macintosh MC240, but I thought that the sound I played with the Q-Tron this time was the best I've ever heard, and when I listened to music on this speaker, I felt a sense of happiness. It must have been a good match. However, when I listened to it with the ME of TAD, which has low efficiency and half the impedance (1 efficiency is 82 dB in 4 ohm equivalent), I didn't get that much happiness. Of course, there is no doubt that it is a good power amp for music playback. The output of this OTL amplifier is 25W, so it may feel a little inadequate when playing with low-efficiency speakers. However, I think that speakers of 90dB or more can ensure sufficient volume. You can choose between balanced and unbalanced inputs.

It was an amp that brilliantly broke the preconceived notion that a good amp would look like this. It taught me that there are still things in the world that I don't know. *See Radio Technology.