Q-tron Audio PA12B 2x25W Push-Pull Tube OTL Power Amplifier
Product code:Q-tron Audio PA12B 2x25W Push-Pull Tube OTL Power Amplifier
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Crystal-clear sound emerges from the silence
An OTL power amplifier born from Nordic craftsmanship, combining transparency and control
High linearity and low-impedance drive achieved by meticulous Futterman-derived design
The output stage of the PA-12 features a Futterman-derived circuit optimized by Q-tron using modern components and analytical technology. The Futterman design, born to drive speakers directly without an output transformer, provides excellent linearity across a wide bandwidth through push-pull operation.
Q-tron advances this traditional design by combining proprietary balance adjustments and stabilization designs, achieving both unwavering control and high transparency even under complex speaker loads. This allows accurate reproduction of the finest musical nuances.
Each channel is equipped with two 6C33C tubes, securing a maximum output of 25W. Even at 10W output, the distortion rate is below 0.1%, and at 1W, it achieves an extremely low distortion of 0.01%.
Noise floor below 100 dBA — active noise reduction supporting silence
The PA-12's quietness is supported by active noise reduction technology.
The noise floor is below 100 dBA. Hum and power-related noise are thoroughly suppressed, allowing delicate signal transients to emerge beautifully.
Nordic precision design — a fusion of 10mm aluminum chassis and PtP wiring
The main board is built on a high-quality PCB, but the parts that directly affect sound quality are carefully finished with point-to-point wiring by skilled engineers.
Designed throughout to suppress mechanical vibration and unnecessary noise, including a 5kV ceramic solder support and a 10mm thick aluminum chassis. All parts and manufacturing are done in Sweden, ensuring high reliability and long-term durability.
Ideal automatic adjustment - advanced auto bias system
Optimization is performed automatically even when replacing vacuum tubes, making it easy to maintain so you can always enjoy music in the best condition.
A new standard for high-end OTL amplifiers that combines quietness, power, and naturalness.
The PA-12, which combines three elements at a high level, naturally depicts the expression of music, regardless of genre, from classical to jazz to vocals.
This is an OTL amp that sets a new standard, combining the beauty of tube amps with modern precision.
| vacuum tube | 6C33C x4, 6H2n-EB x5, 6H6Pi x2 |
|---|---|
| output | 25W (at 8Ω, distortion rate less than 1%), 20W (at 4Ω, distortion rate less than 1%) |
| Distortion rate 1kHz | At 1W < 0.01%, at 10W< 0.1% |
| Frequency characteristics | 5~100kHz/-1dB |
| power bandwidth | 10~100kHz/-1dB |
| Rise time | 0.5μs(microseconds) |
| hum and noise | < -100dBA |
| Output impedance | <0.5Ω or 1.5Ω |
| Input sensitivity | <2.5V (at full output) |
| input terminal | RCA phono + XLR |
| dimensions | 430 x 240 x 400 mm, (W x H x D) |
| weight | 21kg |
The Q-tron PA-12 is an innovative push-pull design vacuum tube amplifier that redefines the possibilities of OTL amplifiers. In addition to the anti-phase Futterman circuit, we employ a unique distortion and noise reduction circuit to achieve an unprecedentedly pure and transparent sound. It delivers sound quality comparable to Class A amplifiers and performs well beyond its realm.
The appeal of the PA-12 lies in its outstanding textural purity and rich tone. Bringing out the essence of the 6C33C power triode, the high range sparkles with vibrant clarity and the low range is powerfully expressed while maintaining extremely precise pitch control. Unlike traditional tube amplifiers, it avoids crossover distortion problems and provides a deep sound field and three-dimensional sound image.
Another noteworthy feature of the PA-12 is its speed in responding to transients (instantaneous changes in sound) and its sensitivity in the high range. With no DC blocking capacitors in the signal path, natural, organic details remain fully controlled. This also conveys bass lines with great clarity and great definition. Capturing all the subtle nuances of music and resolving every detail in any recording, it delivers a listening experience that is both moving and technically superior.
The PA-12 is a true reference-grade amplifier with an extremely low noise floor and extremely accurate reproduction of low-level detail. It captures the essence of music, delivering sound with excellent transparency and clarity, and eliminating unnecessary 2nd and 3rd harmonic distortion.
For those seeking the sonic purity of a tube amp, but with the clarity and resolution of the best solid-state designs, the Q-tron PA-12 is a top choice. In systems where the 25W/ch output is suitable, this amplifier is a true game changer, unleashing the true potential of OTL technology and delivering the musicality and precision audiophiles demand. Highly recommended for anyone looking to take their listening experience to a new level. * 『See “Enjoy The Music”
This machine consists of 11 vacuum tubes. 6H6Pi x2, 6H2n-EB x5, 6C33C x4. Miniature tubes are generally spheres similar to 12BH7A and 12AX7.output tubewas originally designed for use as a regulator, and has an impressive size. It has three horns on its head. When you press the power switch on the front panel, after 1.5 seconds you will hear a light clicking sound from the relay, and the current in the large toroidal transformer will slowly start up. After 90 seconds a second click is heard and plate voltage is applied. After another 45 seconds, the speaker's short circuit is released and you can listen to music. At this time, the edge of the switch lights up green for the first time. It also monitors DC leakage to protect your precious speakers. Please note that if you turn on the power without connecting the speakers, the protection circuit will be activated. Due to the specifications of the 6C33C, it takes 10 minutes to stabilize, so it will probably take more than 30 minutes for the sound to stabilize. The sound I heard was amazing. Whether it's classical or jazz, it has a great sense of realism. No matter what kind of sound you hear, it's really stable even in parts with transients. The volume of the sound in the mid-low range is moderate and pleasant, and you can feel the spaciousness. I was also impressed by how the plucked sounds of the difficult guitars and shamisen came out clearly, and by the high range of the trumpet. This is probably due to the rise time being 0.5 microseconds.
The sound is precise, but it’s not the kind of monitor sound you’d hear in a professional studio; it’s more the kind of sound that lets you really enjoy music. The speakers used for the listening test were the Altec Valencia, which has a high efficiency of 100dB. I have driven them with numerous amplifiers so far, starting from Yamaha’s B1 and McIntosh’s MC240, but the sound produced by the Q-Tron this time seemed the best so far. Listening to music through these speakers gave me a sense of happiness. The compatibility must have been very good. However, when listening with the low-efficiency TAD ME (with half the impedance and an efficiency of 82dB at 4 ohms), I didn’t experience the same level of satisfaction. Of course, it’s still a good power amplifier for music playback, but since the output of this OTL amplifier is 25W, it might feel slightly lacking with low-efficiency speakers. With speakers of 90dB or higher, however, it should be able to provide sufficient volume. Both balanced and unbalanced inputs are available.
This amplifier wonderfully broke the preconceived notion of 'what a good amplifier should be.' It reminded me that there are still things in the world I do not know. *See 'Radio Technology' for reference.
