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My Treasure – "Wrinkles like grooves bring audio wisdom" – 'I loved it more than a meal three times a day' By Otomeijin (August 26, 2005) One of the ways to enjoy audio equipment is to handcraft an amplifier by ourselves. In those days "radios" were prevalent and there were many radios manufactured by makers. Even so, many amateurs tried handcrafting radios because it was interesting. In regard to the audio equipment on the other hand in those days, many of them were radio-phonographs. Although LPs had emerged and we were able to listen to high-quality tones, they were not yet prevailing and not many audio amps for home use manufactured by makers were sold. Even if they were sold, they were naturally too expensive at that time. Therefore, amateur radio enthusiasts including boys and grownups used to handcraft their own amps learning in references and magazines that introduced imported technology from overseas. In those days we made vacuum tube amplifiers (except for some diode, semiconductor devices had not been developed yet) because "otherwise we could not obtain good-quality amps," while nowadays we made vacuum tube amps by ourselves because we want them first of all. So I think the current handcrafting of vacuum tube amps is being done by amateurs in pursuit of high-quality tones as a kind of their hobby. At that time, not a few young boys tried making their own amps with a slogan of "A man like me should be able to make an amp collecting parts" and many of them actually tried. Even now, many of them remain as an expert amateur craftsman of amps, and I hear some of them have become the owner of amp makers.
In my case, I made PP (push/pull)-type Williamson amps such as a 6V6, 6BQ5 and 6AR5, and a 12AX7 pre-amp with a high tuner. As you may know, such numbers as 6V6 means the name of vacuum tubes that are used. I made them by my knowledge and technique that I learned in radio technology magazines and LP technology encyclopedias or by watching my brother-in-law handcrafting amps. First, I decided what kind of amp I would make, taking into account available money I had, and then decided the design of a circuit. Since I did not design the circuit by myself, I selected my circuit design from magazine articles on amp making and from references compiling circuit designs. Based on the circuit design shown on the photo below, I made a parts list and then went to Akihabara. I had plenty of time so I walked around Akihabara thoroughly searching for inexpensive parts, purchasing a resistor at this store and vacuum tubes at that store. Though I remembered the face of the store manager and salespersons, they did not remember me that only dropped by once in a while. When the total price of vacuum tubes and parts was 1,010 yen at a discount, I asked the store manager to make it just 1,000 yen at further discount. But he turned down my request, saying, "Sorry, this 10 yen is our very profit." I understood what he said. Later on after I got work, I also used his remarks so often as an excuse in my refusal. Although it cost me only additional 10 yen, it was a good lesson for me.

Up to this stage I had been serious myself, but on the next stage I smiled staring at those parts I had purchased. I measured the size of the parts and made a detailed layout drawing. I made a chassis of a pre-amp of aluminum board. I made a main amp with unpainted standard-size inexpensive aluminum chassis. I had to process the materials all by myself for cost reduction, making holes by a hand drill and a chassis punch. Most of my amps were the same type as the current models with a rectangular chassis attached with a transformer, electrolytic capacitor and vacuum tubes on its surface.

I especially refined the pre-amp with its power being supplied from the main amp, and with vacuum tubes attached horizontally making the height of the pre-amp as short as the variable condenser, and with a selector lamp switching on/off. It was really good-looking as shown on the above drawing. Making the chassis was quite a job for me without any processing machine like a press or a bending machine, or without a platen. With my desire for better design and without enough tools, I made troublesome efforts, but simultaneously it was interesting. I bended an aluminum board of 1mm thick by pounding it with a wooden material on a concrete block in my garden, and made holes for the tuner dial and pilot using a chisel and hammer. The aluminum board was so soft that it sometimes became wavy and scratched due to the concrete block. I felt "ouch!" but it was no use crying over spilt milk. I felt sorry but the only way I could take was to finish my amp with that spoilt aluminum board, polishing the surface afterwards using sand papers. Could I get a patent for a utility model?―I am kidding, but the lacquer finish looked fairly good. You can enjoy your handmade amps, but you can get an even better finish if you make an order with your own design drawing to a chassis maker. Although there are a variety of chassis design nowadays that is colorful or grain-finished, we could never think of such design in those days.

When I completed the chassis, I soldered the ports and started to attach the chassis with main parts and wires. This made me feel happy and I just ignored my mother's remarks such as "It's time to eat," "Have you studied yet?" or "It's high time you went to bed," just saying "I'll do in a minute!" After wiring and checking repeatedly to my satisfaction, I put the vacuum tubes in and turned on the switch without loading (i.e., without connecting it to the speaker). Before turning on the switch, I was prepared so that I could immediately turn off the switch in case of trouble, and so as to protect my body in case the electrolytic capacitor should have exploded. This made me feel thrilled. If no accident, I measured the voltage using a tester and examined if it was not irregular. Then I turned off the switch for a while and examined if there were those parts that had irregularly heated so carefully that I would not get an electric shock. Actually, I was so excited that I often got an electric shock. Next, I connected my amp to the speaker, turned on the switch, and confirmed the buzz sound when I touched the input hot spot in an instant. From this stage on, I felt satisfied. Connecting cables to the input ports of my handmade amp, I played back a radio and record. Then the sound came resonantly. At this point, my heart beat triumphantly. If the sound was not good as I had expected, I felt depressed immediately―What could I do? If I express the process of my feeling while making an amp, it is as follows: Serious – smiling – happy – thrilled – satisfied – triumphant. The best part of vacuum tubes is that they are something humane. The vacuum tubes are not so small as semiconductors and you can do wiring manually without using a printed wiring board that is complicated like a miniature. Compared with semiconductors, vacuum tubes are voluminous and give an impression not sharp but heavy. They let you feel at ease as if they were illuminating like lamps. Don't you think this feeling is similar to that we have for locomotives in good old days?
	Next week I will skip the topic about the cartridge and speakers and meet our readers' requests. I will start "Seminar by Otomeijin, a fossil man of half a century ago, on making vacuum tube amplifiers"based on my past experience. I will explain about electricity and so on in an easiest-to-understand manner to those beginners who would like to make their own amp for the first time. As an instruction material, I will use a "2A3 single stereo amp," which Hi-Fi Do, a distributor of the Sun Audio equipment, provides. The "2A3 single stereo amp" (shown on the left photo) is the father of vacuum tube amplifiers.

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