Home Audio Stereo HiFi High End Power Amplifier Class A Model A70 100-200W

Launched a new generation of flagship HIEND pure power amplifier products, dedicated to the fans who have been paying attention to and supporting us. The new product adopts a new design, new technology, and new concepts. It has more than 30 years of experience in fever and a deep understanding of music. Joined People-oriented, enjoy music as the purpose, good sound is the last word, completed the interpretation of music as the purpose, with low distortion and high fidelity as the purpose, created today’s A70 flagship pure power amplifier.

We decided to design this A70 after careful consideration. It should not only have the pure Class A output power of the A-65, but also have the dynamic performance of the P-7100. We know that the Class A output has less distortion and the sound is slightly warmer. It is low efficiency and high power consumption, while Class B output has a little more distortion than Class A, but the power consumption is much smaller, so combining the advantages and disadvantages of the two types, a relatively reasonable P-7300 pure power amplifier is designed.

The Class A output power of the original A-65 of Accuphase is 8 ohms and 60 watts, so let’s calculate how to meet this requirement. First, we need to calculate the operating voltage and current required for pure Class A 8 ohms and 60 watts. Due to the maximum output power of the amplifier It is determined by the power supply voltage. For a fully symmetrical circuit using positive and negative power supplies, the maximum output amplitude does not exceed the power supply voltage. If the output exceeds a part, it will cause clipping distortion, which is not advisable in the design of power amplifiers.

So the maximum effective output voltage should be the supply voltage divided by square root 2

The maximum output power is equal to the square of the effective voltage divided by the speaker impedance (8 ohms is used here)

Then 60 watts output power needs plus or minus 31V voltage, which does not consider the voltage drop value of the power tube. Under normal circumstances, it should be plus or minus 35V power supply voltage to output 60 watts of power.

Since 8 ohms are required to output Class A power of 60 watts, then the power is equal to the square of the current multiplied by the load impedance, and 2.74 A is required. If the power transformer cannot output this current, it will not work. The actual value is divided by the root sign 2 = 1.94 A, in Fully symmetrical pure Class A state, up and down

Transistor currents cannot cancel each other out, and a bias current of 1.94 A/2=0.97 A is required in static mode. Since each channel of this P-7300 uses 10 pairs of power tubes for parallel output, each pair of power tubes only needs 100 mA of static power. The current can meet the Class A output of 60 watts per channel. The emitter resistance of the power tube is 0.22 ohms, then adjust and test the voltage across it to 22mV.

The official parameters of the original Accuphase P-7100 are 8 ohms output 125 watts and 4 ohms output 250 watts. According to the measurement of its power supply voltage, it is completely underestimated. We don’t care about this, just give me a reference basis, we combine the actual situation, It is considered that the general household has 8 ohms, 200 watts, 4 ohms, 400 watts output power, and there is no pressure to listen to the big dynamics and push the 12-inch 90db or more speakers. Therefore, according to the calculation, it is concluded that the positive and negative power supply voltages of 58V can meet the requirements.

A good power amplifier power system is like the heart of a person, and the power reserve power is like the blood of a person. Young people are full of blood and have a steady stream of power. Watching foreign excellent audio equipment, they all pay attention to the power part, so our P-7300 is a The output power is 200 watts, but the transformer uses 1200 watts, the filter capacitor uses 320,000 microfarads, and the power reserve is very sufficient. Some people may ask, what is the purpose of doing this? In fact, it is to be able to easily deal with the scene when the big dynamic bursts, such as the Strauss symphony, the normal playback only has an output of 10 watts, and the output of more than 300 watts is normal when the climax comes. If there is no large capacitor and high-power transformer, there is no With enough reserve power, the woofer will be uncontrollable and will be muffled. This is what fans say about soft feet.

~A good power amplifier is not that expensive~

High-end imported audio has now become a luxury item, which has nothing to do with many ordinary people. Firstly, manufacturers deliberately increase the price for profit; secondly, manufacturers have to increase the price in order to pretend to be mysterious; There is such a memorable sentence: “If the price of top equipment such as Krell and Cello is unreasonably expensive, then the price of FM Acoustics is simply unreasonable!” How unreasonable is FM fever equipment? It is said that a stereo amplifier The price of the speaker is nearly 60,000 U.S. dollars, and the 25th anniversary edition of the monophonic power amplifier 2011 (only 25 pairs in total) is asking for 125,000 U.S. dollars; the price of its speakers is said to have reached the point of “full of evil”. It is even rarer.

There is indeed someone’s technology in it, but does it have to be so expensive? Even with such a question mark, I also want to make a work with a sound that can be compared to the “harmful”, but the price must be civilian. A good power amplifier is really not that expensive.

There is no standard for whether a power amplifier is good or bad, so why do “good power amplifiers” sell for 100,000, 200,000, or even millions? What’s so good about it? I don’t know if you have thought about it? Open the lid and see that the materials used in the “famous machine” are worth the money? I am afraid that the parts in a “famous machine” that sells for 100,000 yuan will not exceed 10,000 yuan, so why can it be sold so expensively, because the music it plays fits your ears, making you sound physically and mentally happy and closer to nature sound, what is high fidelity? That is the natural voice, for example, when your friend is talking to you, some people’s voice is round and thick, you feel good when you listen to it, and some people’s voice is sharp, you feel uncomfortable and frown, but this is also true The sound, and it is not distorted, because his voice is the original genuine one. It is not more real than this when it comes out of his mouth and into your ears. This involves a good sound source is also very important, otherwise no matter how good the “name” Machine” You also want to escape after hearing that, haha.

In expensive phones, the cost of components actually accounts for a very small part, and the cost of research and development is even more expensive. The expenses of a “famous phone” R&D team are beyond your imagination, but they are from a “famous phone” manufacturer. Soul, their understanding of music determines the grade of “famous machine”, and each of them must be an expert in music appreciation.

On the other hand, looking at the so-called masters in China, they always like to say “the reason why you are expensive” to fool consumers who don’t know much. There is nothing wrong with this sentence, but their so-called truth is actually bullshit. So-and-so “supplement capacitors”, so-and-so “supplement resistors”, and so-and-so “supplement tubes”, the sound is so good, but there is no “reason” to compare with the original machine, there is only one sentence “it is the original machine”, It’s ridiculous. I’m not saying that “supplement components” are bad, but don’t rely too much on them, because supplements have their own personality. If you don’t know how to use them, it may backfire. Regardless of the quality of each part, it is not good. The difference between bad and bad depends on the user. There are classic examples of this kind of amplifier in Europe and the United States. Very good-sounding power amplifiers are designed with very common components. PASS is one of these examples.

Over the years, while I was making power amplifiers, I was thinking and researching, and a few “whys” popped up in my mind every day. Finally, I figured out that if you want to make a good power amplifier, you must have a good circuit. My understanding is “circuit “It is the “pedigree” of the power amplifier. You can look at many “famous machine” manufacturers who have not changed the fixed line for several years or decades. There are small improvements every year. Yes, so the products of each “famous machine” manufacturer have their own unique voice.

Components are “clothes”, which can only be used for “decoration”, including supplements, so my understanding is “the line is a person’s lineage, then the components are a person’s clothes”, the line is very important, the line is determined, then The sound style has basically been determined. Using different components in the design can not change the style of this power amplifier, but can only modify the tone of this power amplifier. This is like the “prince” who will always be aristocratic. Bloodline, clothes are always his decorations, the same reason.

It has been 43 years since Accuphase was founded in 1973, and the goal of Accurate Phase, which was named when it was founded, has not been relaxed. Why was it named after “precise aspect” back then? Because the person in charge has long known that accurate phases are a necessary condition for a good voice. This is the belief his family has always kept, and of course it is one of the secrets of his family’s good voice for 43 years. Focus: A chassis is exquisitely crafted, noble, and sturdy, and it seems that it will not break after decades of use. 2 Although each channel indicates 125 watts, the power supply is super large, and the net weight of the body is as high as 48.5 kg. The low-frequency control and thrust are excellent, but not rough at all, the sound quality is beautiful, the transparency is feminine, and the resolution is high. The fourth low-frequency control and thrust are excellent, but not rough at all. Suggestion: Versatile personality, all kinds of speakers can show their advantages. Accuphase is a manufacturer with a long history. I visited the original factory, and they gave me the impression that they are a very strict, conservative, Hi-End manufacturer with a strong Japanese spirit. In order to serve users, some parts have been stored for more than 30 years. However, I rarely hear about the failure of its products on the market. Perhaps this is one of the reasons why parts can be stored for so long? If you think Accuphase is an old-school manufacturer that is stuck in its ways, you are wrong. From the day they started their business in 1973, they knew that the source of good sound was Accurate Phase, which is also the origin of the label name. To this day, there are still many audio fans who don’t know what phase is? What is the importance of phase? But they told us the secret of good sound as early as 43 years ago, and accurate phase is becoming more and more important today. Whether it is amplifiers, speakers, digital sources, or cables, engineers are all pursuing accurate phase performance, and use it This is where you get the key to a good voice. Over the past 43 years, they have introduced new models very cautiously and are not greedy for too much. As for the preamp, it has been updated from the original 20 series to the 50 series, that is, 2850 and 3850. Don’t think that every remodeling is for the price increase, they are really more refined, and the AAVA volume control system adopted by the 3850 is changed to a balanced structure, and the perception mechanism of the volume control is also The power transformer has also been changed to make the left and right channels independent. In addition, there are many subtle improvements. In short, Accuphase will not let consumers suffer, and I believe they will continue this spirit. And what about the downstream stage? Accuphase power amplifiers are easy to identify. As long as they are pure Class A amplification, there must be an A in front of the model, such as A-36, A-47, A70, and A200. Class AB amplifiers are divided into stereo machines and mono machines. There is only one mono machine, which is the M-6200, while there are P-4200, P6100, and P7300 stereo machines. If you want to see the output power from the model of the rear stage, it is useless. For example, the A-36 has only 30 watts per channel (net weight 22.8 kg), and the A-47 has only 45 watts per channel (net weight 32.1 kg). The A-200 only has 100 watts per channel (net weight 46 kg), which is not comparable to the model. Not to mention the Class AB P-4200 (90 watts per channel, net weight 28.9 kg) and P-6100 (110 watts per channel, net weight 42.7 kg). As for the P-7300, it has an output of 125 watts per channel (8 ohms) and a net weight of 48.6 kg. Output Power-to-Weight Ratio When you see this, you may find something different about his family, which is the “output power-to-weight ratio”. Why is the output power of his power amplifier so small? But the body weight is so heavy? This is what makes Accuphase amplifiers so popular, and it is also one of the key points that gives consumers confidence in their products. Although the output power of his 8-ohm load is not large, it can withstand a 2-ohm load when listening to music normally, and the short-term withstand power can be as low as 1 ohm. No other manufacturer can achieve such a mark. For example, although the P-4200 only outputs 90 watts per channel at 8 ohms, it can output up to 360 watts at 2 ohms and 500 watts at 1 ohm. In fact, you can think of the P-4200 as a power amplifier with an output of 360 watts per channel. Why is the output power of the Accuphase power stage not very high when loaded with 8 ohms, but the body is so heavy? Of course, the power supply is very solid, and the cabinet is also very solid. The weight of the power stage comes from these two places. Seeing this, you should understand the value of the Accuphase power amplifier, right? The heart of the post-stage is the power supply. If there is no solid power supply, those high current and high power outputs are just “claimed”. Once they encounter large dynamic music, they will immediately go limp. Of course, the cost of a solid power supply is high, which is why the Accuphase power amplifier is sold at such a price. However, in good conscience, the pricing of Accuphase power amplifiers is actually very reasonable. As long as you have used their power amplifiers, you will definitely agree with me. The P-7300, which was remodeled after 7 years, is the top stereo power amplifier of his family. Its predecessor was the P-7100, which was launched as early as 2008. After so many years, the upgraded model was launched. The remodeling can be said to be quite cautious. The internal technology of the P-7300 is inherited from the A-200 pure Class A power amplifier and the M-6200 mono power amplifier. dB, if it exceeds 0dB, it will be red, indicating the beginning of distortion. The 0dB point is also the 100% output point. Generally, it is impossible for the pointer to hit the red area when listening to music, so don’t worry. Below the meter head, on the left is the meter head switch button. You can choose Normal, Hold for 3 seconds, Hold for unlimited time, or turn off the meter head light. In the center is the power switch. Next is the Input switch, and on the far right is the Gain switch, which has four levels: Max, -3dB, -6dB-, and 12dB. This set of gain switches is directly connected to the input stage of the P-7300, converting the gain size at the source. There are two sets of lights on the top of the meter head, the left side shows the status of the meter head Hold, and the right side shows the status of balanced or single-ended input, and the status of bridged, normal or dual amplifiers. Looking at the cabinet of the P-7300, its panel is very thick at 20mm, and the left and right handles and the rear handle are also very large, giving people a sense of 100 points of trust. The heat sinks on the left and right sides are huge, but the edges are rounded and painted with a gray surface treatment, which will not scratch hands and feet. This is also the “thoughtfulness” of the Japanese. There is a crossbeam connection in the center of the heat sink, which strengthens the huge heat sink on the one hand, and provides the vibration suppression ability of the heat sink on the other hand. When you come to the back panel, you can see four sets of huge speaker cable terminals, two sets for each of the left and right channels. This kind of speaker cable terminal is very strong, which makes people feel the factory’s intentions. There are two sets of RCA terminals and XLR terminals under the huge speaker cable terminals, one of which is written Bridge, which means that the unit can be bridged into mono. In the bridged state, each channel outputs 500 watts (8 ohmic load). In addition, there is an XLR terminal to switch between American and European standards, which is also very considerate. If it is American, you have to choose 1, 2, positive and 3 negative, and European rules choose 1, 2, 3 positive. Don’t get it wrong, it will make the music signal out of phase. Finally, there is an important switch on the back panel, which is Normal, Dual Mono, and Bridge. Normal is the two-channel usage state, and Dual Mono is the Bi Amping usage mode. There is no need to explain the bridge. Such switching design also shows the thoughtfulness and thoughtfulness of the designer.