History develops in a spiral. It's time to create a tube amplifier. It turned out to be not at all easy. It was necessary to turn off the postulates of the transistor vision of the world within ourselves, to rebuild everything under the tube one. There is practically nowhere to get knowledge: books on lamps have mostly gone to the trash. I had to dig up the Internet. It took about a year to find knowledge and an acceptable scheme for repetition.
At first I wanted to make A class with 2 6P3S in parallel, but rejected this scheme. I thought 6 watts would not be enough. Then I came across Manakov’s 6E5P - GM 70 23 watt A class circuit. For eyes. Difficulties began where I did not expect. 1 where to find IRON. My feet took me to the oldest cinema in the city. It turned out that the smoking room was alive. In the basement there were LOMO U 013 tube amplifiers lying and waiting for me (inscription on the nameplate). 2 clock on 6Р3С. The unshaven electrician gave me four of them and a whole box of 5Ts3S. My breath was spiraling with happiness. The iron was twisted from there to 30 kg. The manufactured output trance passed 35 kHz without decay. I made it from two Ш plates placed on top of each other, I borrowed the idea from Demchenko. I soaked the coils with an ointment made from wax welded with transformer oil (I came up with this myself). The cross section of the iron is 18 cm square. weight 7.5 kg. Look here:
The next problem with the socket under the GM-ku is not present and is not expected. I solved it in my own way: a flange was machined from stainless steel in which the skirt of the lamp is secured with a screw-pin,
The flange itself is attached to the top panel of the case, and the contacts are removed from a powerful military connector and brought to the required diameter with a drill.
As I gained knowledge in tube science, I decided that the coupling capacitor was worse than the coupling trans. Then I came across A. Shalin’s diagram, kindly posted for everyone to see:
And I must say it’s very laconic. I found from the network about 20 circuits on GM 70 and 211 lamps, but I immediately liked Shalin’s circuit, I decided to stop with it, contacted him, asked how the interstage trans was designed, and made it according to his recommendations. For which I thank him very much. From theatrical hardware, the -3dB band turned out to be 8Hz 38kHz:
The GM 70 filament is powered by a torus. In an electrical goods store you can find tori for illuminating display cases with 12V halogen lamps
In this 200 W trance, 12 V is wound in 2 wires. Minimal alteration and you have 20V with an ideal midpoint.
The anode GM70 is powered by the TS180, can you photograph it? It was made according to the doubling scheme on 5Ts3S. For each kenotron there is a capacity of 20 microfarads * 500V, extracted from those amplifiers and then 2 capacities in parallel
choke 10 Gn 12.5 cm of iron is almost half the output and the main capacitance MBGV is 200 μF * 1000 V. In the reference book on containers it is said that it works well in pulse mode, which was the reason for choosing it. Actually, I stole this food again from Demchenko, in his?ongaki’s scheme. Although you can’t stupidly repeat it, one kenotron is connected incorrectly. The grid bias here is all just 4 fast diodes, a P filter, although there are already electrolytes and not BG, there is nowhere to get them. But at least the shunted K40U9. and the throttle is the simplest from the TV set 5-0.08. With a quality mark. And also a resistive divider to adjust the mixing. Everything seems to be okay with GM nutrition.
Now 6E5P is powered by its own transformer for iron, similar to the interstage one, it’s even a pity to waste it there, it’s too good. anode according to the scheme as a grid one for GM 70. Heat with a midpoint. Everything is simple here. How many diagrams had to be revised to simply say this.
The hard stuff is over. Although there is one more trance. I'll tell you about it later.
Weight with the housing per channel gained 28 kg. I would recommend starting to build an amplifier with the chassis. Because installation on plywood often ends there, unless electrical injuries happen to loved ones.
Here's what it looks like before painting.
The output trans was placed on top of the amplifier. It is closed with a large stainless steel cylinder (from household goods - a container for food) under a small separating trans (a mug with a torn off handle) and another MBGV, to which I soldered 2 ears for fastening.
I made the volume using an autotransformer. The hardware, if you can call it that, was taken from a Kip amplifier with 2 tubes.
it turned out to be a permalloy and skipped the band linearly up to 55 kHz, and my generator does not generate any further. P iron 1.2 cm rod type.
There are 5500 turns of 0.1 on 2 coils with taps for 12 switch positions. 35 H winding inductance. In our city there is a certification center; in the laboratory there is a device that measures elephant Hn, so here’s a chocolate bar and there. Measure. This is a hint where to find the L meter.
is a radio tube developed and produced in the Soviet Union. Designed to enhance power audio frequency, in radio transmitter modulator circuits, in broadcast amplifiers and generators. Its power is high, but somewhat less than that of a triode.
Typical operating parameters
- Type of electrode system - triode
- Heat - direct
- Base - special
- Decoration: glass
- Lamp anodes were made of copper, steel or graphite.
The tube was often used in short-wave amplitude modulation radio transmitters to control the level of the output signal by varying the voltage at the anode of the output generator tube. It was also used in broadcast amplifiers, for example TU-5-3.
Among radio amateurs, the GM-70 has found widespread use in homemade structures low-frequency amplifiers designed for high-quality sound reproduction. The advantages of the lamp are low internal resistance, high output power, linear current-voltage characteristics. It is capable of delivering up to 15 W in class A, up to 40 W in class A2 and up to 170 W in class B2.
Queen of triodes called GM-70 by radio amateurs for its high power and linearity of characteristics, as well as the beauty of its appearance.
In this circuit, the cathodes of the driver tubes are placed on the ground, therefore there is a fixed bias. A 6P3S in triode connection works as an output driver. The main power filter capacitors are located in the power supply itself. The amplifier blocks contain only a few non-polar capacitors of small capacity to power the input and driver stages.
History develops in a spiral. It's time to create a tube amplifier. It turned out to be not at all easy. It was necessary to turn off the postulates of the transistor vision of the world within ourselves, to rebuild everything under the tube one. There is practically nowhere to get knowledge: books on lamps have mostly gone to the trash. I had to dig up the internet. It took about a year to find knowledge and an acceptable scheme for repetition.
At first I wanted to make A class with 2 6P3S in parallel, but rejected this scheme. I thought 6 watts would not be enough. Then I came across Manakov’s 6E5P - GM 70 23 watt A class circuit. For eyes. Difficulties began where I did not expect. 1 where to find IRON. My feet took me to the oldest cinema in the city. It turned out that the smoking room was alive. In the basement there were LOMO U 013 tube amplifiers lying and waiting for me (inscription on the nameplate). 2 clock on 6Р3С. The unshaven electrician gave me four of them and a whole box of 5Ts3S. My breath was spiraling with happiness. The iron was twisted from there to 30 kg. The manufactured output trance passed 35 kHz without decay. I made it from two Ш plates placed on top of each other, I borrowed the idea from Demchenko. I soaked the coils with an ointment made from wax welded with transformer oil (I came up with this myself). The cross section of the iron is 18 cm square. weight 7.5 kg. Look here:
The next problem is the socket under the GM-ku - it does not exist and is not expected. I solved it in my own way: a flange was machined from stainless steel in which the skirt of the lamp is fixed with a screw-pin,
The flange itself is attached to the top panel of the case, and the contacts are removed from a powerful military connector and brought to the required diameter with a drill.
As I gained knowledge in tube science, I decided that the coupling capacitor was worse than the coupling trans. Then I came across A. Shalin’s diagram, kindly posted for everyone to see:
And I must say it’s very laconic. I found from the network about 20 circuits on GM 70 and 211 lamps, but I immediately liked Shalin’s circuit, I decided to stop with it, contacted him, asked how the interstage trans was designed, and made it according to his recommendations. For which I thank him very much. From theatrical hardware, the -3dB band turned out to be 8Hz 38kHz:
The GM 70 filament is powered by a torus. In an electrical goods store you can find tori for illuminating display cases with 12V halogen lamps
in this 200 W trance, 12 V is wound in 2 wires. Minimal alteration and you have 20V with an ideal midpoint.
The anode GM70 is powered by the TS180, can you photograph it? It was made according to the doubling scheme on 5Ts3S. For each kenotron there is a capacity of 20 microfarads * 500V, extracted from those amplifiers and then 2 capacities in parallel
choke 10 Gn 12.5 cm of iron is almost half the output and the main capacitance MBGV is 200 μF * 1000 V. In the reference book on containers it is said that it works well in pulse mode, which was the reason for choosing it. Actually, I stole this food again from Demchenko, in his?ongaki’s scheme. Although you can’t stupidly repeat it, one kenotron is connected incorrectly. The grid bias here is all just 4 fast diodes, a P filter, although there are already electrolytes and not BG, there is nowhere to get them. But at least the shunted K40U9. and the throttle is the simplest from the TV set 5-0.08. With a quality mark. And also a resistive divider to adjust the mixing. Everything seems to be okay with GM nutrition.
Now 6E5P is powered by its own transformer for iron, similar to the interstage one, it’s even a pity to waste it there, it’s too good. anode according to the scheme as a grid one for GM 70. Heat with a midpoint. Everything is simple here. How many diagrams had to be revised to simply say this.
The hard stuff is over. Although there is one more trance. I'll tell you about it later.
Weight with the housing per channel gained 28 kg. I would recommend starting to build an amplifier with the chassis. Because installation on plywood often ends there, unless electrical injuries happen to loved ones.
Here's what it looks like before painting.
The output trans was placed on top of the amplifier. It is closed with a large stainless steel cylinder (from household goods - a container for food) under a small separating trans (a mug with a torn off handle) and another MBGV, to which I soldered 2 ears for fastening.
I made the volume using an autotransformer. The hardware, if you can call it that, was taken from a Kip amplifier with 2 tubes.
it turned out to be a permalloy and skipped the band linearly up to 55 kHz, and my generator does not generate any further. P iron 1.2 cm rod type.
There are 5500 turns of 0.1 on 2 coils with taps for 12 switch positions. 35 H winding inductance. In our city there is a certification center; in the laboratory there is a device that measures elephant Hn, so here’s a chocolate bar and there. Measure. This is a hint where to find the L meter.
The lamp was used in short-wave amplitude modulation radio transmitters to control the level of the output signal by changing the voltage at the anode of the output generator lamp (anode modulation).
The lamp was also used in broadcast amplifiers, for example TU-5-3.
Homemade designs
The lamp has found wide application in home-made designs of low-frequency amplifiers, both for concert purposes and those intended for high-quality sound reproduction. Advantages of the lamp: low internal resistance, high output power (up to 15 W in class A, up to 40 W in class A2 and up to 170 W in class B2), linear current-voltage characteristics.
Lamp nicknames
“Queen of triodes” - called by radio amateurs for its high power and linearity of characteristics, as well as for its external beauty.
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See what “GM-70 (lamp)” is in other dictionaries:
General purpose(230 V, 60 W, 720 lm, base E27, overall height approx. 110 mm Incandescent lamp electric source of light ... Wikipedia
Black light lamp, or Wood's lamp, (English: Black light, Wood's light) a lamp that emits almost exclusively ... Wikipedia
Lamp: Wiktionary has an entry for “lamp” Lamp (Chile) Spanish. Lamp) ... Wikipedia
Black light lamp A black light lamp, or Wood's lamp, (English: Black light, Wood's light) is a lamp that emits almost exclusively in the longest wavelength ("soft") part of the ultraviolet range and produces virtually no visible light.... ... Wikipedia
Black light lamp A black light lamp, or Wood's lamp, (English: Black light, Wood's light) is a lamp that emits almost exclusively in the longest wavelength ("soft") part of the ultraviolet range and produces virtually no visible light.... ... Wikipedia
There are stories among sound lovers about the high sound quality provided by GM-70 triodes. But this is quite difficult to confirm and equally difficult to refute in practice, since these lamps are hefty. And therefore, for the practical implementation of an amplifier project on such piglets, large resources, money and time are required. Example of a picture from the general network access shown below. It is difficult to understand the sizes of lamps without having a comparison. But these sizes are not small, a little smaller than a loaf of bread. Probably as thick as a baguette of foreign invention.
And dealing with such sausages is not at all easy. It is characteristic that in the second picture there is a special bedside table for each two-stroke monoblock. This is not just a nightstand. This is a power supply, and it is made thoroughly. A normal tube amplifier like this can weigh 70 kilograms each. And these are not childish weight and dimensions and high heat generation. The drawing and specifications are shown below.
Moreover, if suddenly the result of one’s own design of an amplifier using such lamps turns out to be unsatisfactory, then who will publicly admit this?! No? Think for yourself, decide for yourself whether to have it or not.
GM-70 lamps have advantages and disadvantages. Also decide for yourself what to classify as what. Directly heated cathodes. Anodes can dissipate a hefty amount of power. To reliably drive the output stage, you need an additional resource in the form of a driver. The picture turns out to be beautiful, but the path is not easy. And yet the one who walks will master the road. Below is a diagram in which you can look for success. The circuit uses a standard output stage with differential connection of hefty matching transformers (150-200 W each) and cathode feedback for linearization. Incandescent background alternating current defeated by the use of handmade incandescent transformers with perfect symmetry.
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There is no need to be afraid of differential switching of transformers. All schemes are quite simple. The primary windings must be split and connected in series crosswise. And the secondary windings are connected according to the principle of expediency, in series, parallel or combined. By doubling the number of transformers, it is possible to play out the ampere turns and allow increased voltage, if lamps allow. But you need to keep in mind that transformers must have high degree symmetry. In practice this is difficult to achieve. That is why circuits with differential connection of outputs have not found widespread use. If you need to introduce a general feedback, then you need to add another amplification stage, reducing the transmission coefficient. Everyone must decide for themselves whether to introduce general environmental protection or ignore it. There are too many lies and verbiage in this topic.
Next to it there is also an Internet picture of an amplifier built on GM-70 lamps and made very carefully. The product turned out to be quite nice, and the author is very talented. However, this implementation is unacceptable to me. And not at all because a rubber enema flask is visible in the background. And only because a single-cycle circuit solution was used. By the way, the caps used are excellent. And the rest of the accessories used in the amplifier look great. But a moped is a moped, even with a Belaz engine. May the gurus forgive me. Amen.
GM-70 triodes are quite nice appearance. Their number is limited. But you can buy them here in proven pairs, at a price 25% lower than in Istok. Tube amplifier You can also buy such beauties here with prepayment. But it will cost quite a lot, from 220K and above. To purchase, just contact me by mail, discuss the price and delivery conditions, pickup is possible. After this, the person interested should call the phone number indicated on the website to discuss the details, and only then make an advance payment of 20% of the agreed amount to my Sberbank account. Having received the transfer, I send a notification and within two weeks I will call you back with confirmation of proper packaging of the product and readiness for shipment, and I will send photographs of this particular unit, opened and packaged, by email. For shipment, the buyer is required to transfer the remaining amount, after receiving which I carry out the shipment and email a copy of the receipt. If the buyer's circumstances have changed within the specified period of time, then the purchase can be refused. The listed deposit is not refundable. The amplifier has a 12 month warranty from the date of delivery. The warranty does not apply to glass sent by post or transported by a transport company. Sincere wishes to everyone good health and success.
Evgeny Bortnik, Krasnoyarsk, Russia, November 2017
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