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Tag: preamplifier

BC109 Direct Coupled Preamp

It’s a very nice, warm, full-tone preamplifier. The soul of the circuit is two BC109 transistors. These are old, well-proven types. Interestingly, the base of transistor T2 is connected to collector T1. This is called direct coupling, and the signal is transmitted between stages without attenuation. This means that there is no capacitor, resistor or transformer between the two transistors. This makes it less repressive to the guitar signal. This circuit does not distort, that is, only when the guitar volume is at its maximum.

This is the first version:

Direct Coupled Preamplifier with BC109 Transistor
Direct Coupled Preamp Schematic

In this video it works on 9v voltage, see:

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LM386 Overdrive Effect

LM386 overdrive: easy, cheap, and fast to make. This is known and popular audio amplifier circuit with a fairly simple but good sounding overdrive guitar effect. Neither the operation of the complex.

LM386 Overdrive Guitar Effect
LM386 Based overdrive guitar effect

BS170 mosfet guitar signal to the already worsened. the R8 potentiometer regulates the amount of signal to the 386. If you have more than that the chip can handle, then the signal will be distorted. That is, the overdrive. So it is quite dry and rough sound. And of course it’s good for us. Listen to:


High voltage tube guitar preamplifier with 12AX7

The high voltage tube guitar preamplifier project is an adaptation of the famous tube preamplifier to suit the DIY’ers demands. Searching the net, I’ve never come across similar idea, so I decided to share this version of our very popular design. This a classic, conservative design, that easily matches other musical devices.
The preamp contains one channels of real-tube, high-gain circuit. This circuit uses JJ ECC83 (12AX7) tubes. Circuit uses a stabilized 12V DC voltage.

High voltage tube guitar preamplifier
High voltage guitar preamplifier circuit

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