You may be wondering why I am using four tubes. The reason is to get 50 watts without pushing them right to their limit. My tube manual gives two setups for EL34s in ultra linear. Both require a 6 k ohm transformer. Both setups use exactly the same voltages but one says you get 20 watts at 0. 34 percent distortion and the other says you get 34 watts
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at 2. 5 percent distortion. The applied voltages are the same except for the AF grid drive voltage. They are just driving them harder to get more power and more distortion. Connecting four tubes in push-pull parallel lowers the load resistance to 3 k, which almost matches a transformer I have already bought, and gives more power with not a lot of distortion. I could almost live with it with no global feedback. I don`t know how Eico got 50 watts with two tubes but it is likely I am remembering it wrong and they were actually 35 watt amplifiers. See farther down this page. This is the amplifier I`m going to build. The tube manual data is for cathode bias so I`m going to see if I can`t simplify the circuit. The screen voltage regulator is already gone and if I can eliminate the negative voltage supply I`ll have a really good circuit. I`ll post it under its own heading on the front page when it is finished. Because of the extremely low powers at the low frequency end, from the Hammond transformer, I measured the distortion at various frequencies at 12. 5 watts (6 dB below maximum rated power. There is no reason to do the same for the Edcor. Distortion in the bass is readily apparent because all of the harmonics are in the range of a speaker to reproduce. Also most of the power in pop music is in the bass end. Just think of those cars with subwoofers that rattle the windows in your house as they drive by. Even in jazz or...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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