Uncover the secret of great vacuum tube sound

                     Uncover the secret of great vacuum tube sound

Do you also like to listen to vacuum tube speakers? The pleasant sound it produces comes from the vacuum tube circuit, and many factors are taken into consideration to achieve such a pleasant sound quality. The author will share with us his experience in self-study of vacuum tube circuit technology, teach us how to select vacuum tubes and analyze the impact of different factors on sound, and reveal the secret of good sound.

Why vacuum tubes sound good, of course, has its unique conditions. You can see the clues from the characteristic curves of vacuum tubes and transistor characteristics. Vacuum tubes are used in speakers because of their charming sound, so many people must listen to vacuum tube speakers. Many people also want to learn vacuum tube circuit technology, but since I taught myself 30 years ago, there are few or almost no vacuum tube circuit courses in Taiwan. There is a lot of data on the Internet, but it seems that they don’t understand it. How to learn vacuum tube circuit technology? , share my learning process here.

Learn introductory vacuum tube circuit technology

For basic introductory data and theory reading, I recommend two books. The first is the RCA RC-30 1975 Hand Book, which was a reference book for learning vacuum tubes back then. Of course, it is a reference book that you must read carefully. You will need to look for information carefully. During research, I found out where it is.

The second book is Valve Amplifiers (Fourth Edition) Morgan Jones. Please download it from Google. This book carefully teaches you the calculations of various basic circuits, allowing you to understand the screen voltage and screen voltage of various operating points during circuit design. flow, screen resistance, bias, bandwidth, etc.

6DJ8 vacuum tube characteristic curve

When these basic calculations are used in future circuit design, we will not just see the circuit, but will consider more conditions. These conditions will affect the circuit design. When considering the selected vacuum tube model, circuit architecture combination, etc., how to match the combination? Most consistent with the overall circuit design goals. After studying the above data carefully, you can only get started by applying it to circuit design and calculation.

How to choose the best vacuum tube

Want to learn more about vacuum tubes? There is no explicit knowledge in the original factory data. As for what vacuum tube to use, you need to carefully study the original technical data of the vacuum tube. Only by studying it in depth can you understand how to best use this vacuum tube? How to achieve the best balance between screen consumption, screen pressure, screen flow, power output, safety, durability, and sound quality. When you see more circuits, you can quickly see the advantages and disadvantages of this circuit and its designer. idea.

After you have considerable experience in designing circuits and making machines, you can quickly and correctly judge the problems of the machine. When you slowly see the circuit, you will have a sense of its operation, because the circuit design is static, but the circuit operation is dynamic. Only here can you Make sure that the circuit design is close to the expected actual operation. Otherwise, the actual operation is often not as good as expected. That is to say, when designing the circuit, you must take into account the various dynamics of the actual operation. Slowly, the circuit design will be consistent with the actual operation. Expectations are close to the same.

In addition, you should also have a deep understanding of the output transformer's core material, winding method, relationship between primary impedance and power tube working line, frequency response, etc., so that you can make the best choice when choosing an output transformer in the future.

Understand the impact of different factors on sound quality

The next step is to have certain experience and understanding of most brand series, such as Rubycon, Nichicon, Panasonic, Philips, ROE, Rifa, CDE, Wima, UCC (Sprague), Epcos, etc. You also need to understand capacitors and resistors made of various materials. Capacitors include electrolytic capacitors, PP capacitors, laminated capacitors, tantalum capacitors, etc.; resistors include wire-wound resistors, metal film resistors, carbon resistors, non-inductive resistors, etc.

The related use of these parts has an impact on the sound. Having a certain understanding of the internal structure of your commonly used vacuum tubes will help you make correct judgments when choosing NOS vacuum tubes. It will also be helpful when purchasing new manufactured vacuum tubes. New and old ones There are many vacuum tubes, and you need to have a deep understanding of how to choose them. After all, they are the main components used.

In addition, you must have the ability to use other active components such as transistors, MOSFETs, OP AMPs, and ICs. Sometimes they are used in power circuits or auxiliary circuits, or even in combination. Don't just limit yourself to vacuum tubes. Every component has them. Advantages and disadvantages, you must be able to use their respective advantages to form your own ideal circuit.

In addition, you must have certain experience in using various wire materials, single-core and multi-core, thickness, isolation or insulation layers. In addition, wiring is also a knowledge. The wiring on the circuit is divided into receiving signals and transmitting signals. How to route the wires? The key point to consider when wiring is to avoid interference. Whether the wires should be twisted or run at right angles depends on inductance and stress factors. The standard for wiring is to put your ear against the speaker and no hum will be heard when the volume is turned up to maximum.

Wiring will also affect the sound performance. Inductance factors, induction factors, etc. can only be experienced individually. Of course, there are also solders, fuses, socket plugs, switches, VR, etc. You also need to have a certain understanding of them to avoid spending a lot of money on places that have little impact.

The above experience can help you choose the materials you need. You can choose all the best materials, or you can choose to spend money on materials that affect the sound quality more. Only by constantly trying can you have a certain ability to adjust the sound.

Finally, in the material part, it is reminded to use the best tube holder CMC, otherwise it is to use a large eight-pin vacuum tube. It is important to avoid the problem of poor contact.