This is the schematic of the final design including the tone stack but leaving out the volume, balance, and sonic controls. The right half of the circuit is John Broskie's original White cathode amplifier with a pair of 5687s as output tubes. This lowers the output impedance to about 27 ohms (gain remains the same) and allows me to set the quiescent current at 17mA per section to preserve tube life while still achieving high current swings with lower distortion. I've increased the size of the output capacitor to get a better lower frequency response at lower load impedances and added good quality audio caps in parallel with the electrolytics. I also added a fuse after the output capacitors to protect the headphones just in case the electrolytic fails someday.
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The 10M resistors (R5 and R13) on the grids of the 12AU7s are not strictly necessary. I included them, however, because I was going to build the amp in stages. I knew that at some point I would want to power it up to measure bias voltages before the volume and tone controls were wired. I needed these resistors to ground the grids and set the proper bias points. I could have just as easily used temporary clip leads to ground the grids when measuring voltages, but adding resistors was not that much extra trouble.
The Fender tone stack is a pure boost tone stack. Unlike the equally well-known Baxandall tone stack, the Fender stack cannot provide bass or treble cut. But, since I never listen with bass or treble cut, the Fender stack offered fewer components and complete capacitor coupling thereby avoiding the use of an additional coupling capacitor from the plate of V1. Like all tone stacks, the Fender tone stack has an insertion loss, in this case approximately 18dB. The "boost" actually comes relative to this loss. In the Fender stack, the mid control is only really active if there is bass and/or treble boost. When the bass/treble controls are off the mid control becomes another volume control.
The parts of the stack form several high-pass filters. The upper part is a high-pass filter through the 250pF capacitor into the treble control whose wiper feeds the next stage. The high-pass bass filter (through the 0.47uF...
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....
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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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