MC-275 Taiwan Team's Road to Reproduction
Over the decades, McIntosh can be said to be one of the few famous brands that has always maintained its prominent image. At that time, its first stereo power amplifier, the MC240, was officially launched. Its output per channel reached 40 watts, while the total harmonic distortion was only 0.5%. It was considered a classic at the time, but if we talk about the most famous one through the ages, McIntosh's MC275 vacuum tube amplifier is the dream lover of audio lovers around the world. It has to be the McIntosh275. The MC275 was launched in 1961. It was designed by Sidney Corderman, co-creator of McIntosh, and the McIntosh design team, and then born.
After 13 years of continuous exploration and listening to customer feedback, in 2023, the Gaolifeng Taiwan team launched the 6th generation flagship MC-275 amplifier. The belief that the team has been pursuing! After many trials and combinations, the KT88 tube is customized for the first time and is exactly the same as McIntosh. Both the structure and parameters are the closest to the old version of the bile duct. When paired with the customized Gollo Feng bile duct, the sound is better than the Russian * Golden Lion, EH" It has charm, is quieter and has more stable quality, no matter the cost. The components and carefully selected matching tubes make the sound more authentic and flavorful than the modern replica tubes on the market. The entire machine is completely handmade, so the construction period is relatively long. The independently developed automatic bias adjustment technology for vacuum tubes is the first on the market. What the 275 does not have (detailed introduction below), the sixth generation flagship version can also be used as a combiner or a power amplifier. The stereo mono channel can reach 75W, and the mono channel after bridge can reach 150W (equivalent to a stone machine). 400W), such a large power, whether it is hundreds of thousands of large floor-standing 15-inch speakers or flexible Boxes with ultra-low sensitivity can be pushed with ease, and the tube amplifier's vocals are more mellow, delicate and emotional. The soul transformer of the amplifier, the sixth-generation flagship transformer adds a purification module for the first time, which means that a new frequency conversion working method is used to stabilize the output voltage, that is, the frequency is changed once in each cycle of the output AC voltage, such as the first cycle It is 50Hz, the second period is 120Hz, and the next period returns to 50Hz. The sound quality will be better than using a fixed higher frequency. All transformers are one-to-one according to McIntosh 27 5 are wound with precise algorithms, and all are made of single oxygen-free copper material with a purity of 99.99%. It is emotional and has full thrust. No matter how hard it is, the speaker can be pushed easily under 275, and the sound is sweet, soft and natural. Careful, open and wide sound field, listening to large-scale orchestral music is especially exciting. The all-gold-plated design of the previous generation circuit board is extended to make the quality more stable and long-lasting. You can easily feel the distinct parts, the ups and downs of the music, the thick and full sound base, and the rich and powerful low frequency, making the music full of power and vitality. 
Pursuing distortion-free and color-free right-characteristic custom tubes
The flagship version of the customized replica KT88 high-power RF tube is a right-characteristic tube. Unlike the left-characteristic power tubes such as 300B845, the gate works at a positive voltage and has a gate current. The gate of the left-characteristic power tube works at a negative voltage, has no gate current, and is easier to design. The right-characteristic tube reduces input impedance interference due to the existence of gate current, and is very good at using high-power drive, while the left-characteristic tube only needs voltage drive. If the customized KT88 tube MC-275 is to output 75 watts of maximum undistorted Class A power, it requires a certain amount of power to drive. Generally, a triode or a high-transconductance collector-emitter quadrupole is used, and the pentode is connected to a triode for driving. It is also useful to drive a transformer. The custom tube design just overcomes this coloration and background noise, so as to better and more stably play the taste of the tube.
KT88 is a beam power tetrode with a maximum anode dissipation power of 42W. In an audio amplifier, two tubes can achieve 75W of power when used as AB1 push-pull output. KT88-T can also be used in electronic voltage stabilization circuits. KT88-T is similar to 6550 and can be used interchangeably.
UH…………………………………………………………….6.3V
IH……………………………………………………………..1.6A
Maximum Rating
Anode Voltage…………………………………………..800V
Second Grid Voltage……………………………………..600V
First Grid Voltage………………………………………..200V
Anode Power Dissipation…………………………….42W
Second Grid Power Dissipation……………………8W
Anode plus Second Grid Power Dissipation……..46W
Cathode Current……………………………………… 230mA
When the first gate resistor is self-biased
Pa+Pg2≤35W 0.47 MΩ
Pa+Pg2>35W 0.27 MΩ
When the bias is fixed
Pa+Pg2≤35W 0.22 MΩ
Pa+Pg2>35W 0.10 MΩ
Inter-electrode capacitance
Tetraode connection method Triode connection method
Input capacitance……16 9.3 PF
Warm and rich live performance
The biggest charm of the sixth-generation flagship MC-275 is its gorgeous texture and clear transparency. The mid-frequency is smooth and elastic. The three-dimensional sense of human voice singing is prominent. The sound field is very wide, the left and right are pulled far away, and the front and back layers are very clear. This feature is toxic for appreciating string music and human voice. The piano solo can especially bring out the texture of large and small beads or jade plates. Under the condition of unchanged output power, the dynamic fluctuation ability of the customized version of KT88 always makes the music more expressive. It takes time for the ultra-high frequency to loosen and soften, but the MC275 makes people admire the air and overtones as soon as it is turned on. The details are naturally revealed, the sound quality is noble and emotional, and the violin is charming. In large-scale orchestral music, no matter how explosive the music is, the flagship version has never been weak. Compared with the fifth generation, the strong kinetic energy always attracts attention and makes people linger.
Product name: The sixth generation of Taiwan flagship version Gao Lefeng MC-275
Output impedance group: 4Ω 8Ω 16Ω
Output power: 75W for stereo mono and 150W for mono bridge method
Tube model: Four selected KT88 tubes, three selected 12AX7 tubes, four selected 12AT7 tubes
Frequency response: 10Hz-50kHz
Harmonic distortion: 0.5%
Signal-to-noise ratio:》98dB
Input sensitivity: 400mV
Fuse specification: Fast-dissolving type 250V3-4A size is 6×30 or 6×32
Power supply voltage: 220V 110V can be adjusted manually
Overall size: 410*360*230mm (length*width*height)
Product use: Can be used as a post-stage or can be used as a combined power amplifier with RCA audio line input XLR balanced input can only be used as a post-stage and needs to add a pre-stage
Precautions for electron tubes
Electron tubes have the lowest distortion and the best sound when they are preheated. They have the longest working life when they are fully preheated, so it is recommended that customers wait for a while after turning on the machine and the sound will get better and better as it ages.
The normal life of electron tubes is several decades. If used under the above description, there is no need to consider changing tubes frequently.
When changing tubes, you need to pull them upwards, and try not to swing them left and right, otherwise the tube pins will loosen. Once oxygen enters the tube, the electron tube will basically be scrapped, so you need to pay more attention.
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