Name: op-amp preamp for a vintage console
Uploaded: 2026-08-04T14:08:12.571Z
Duration: 1 min 17 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Specialised Topic in Science

112.51.c.1.

112.51.c.2.D.

Design Example: Vintage Mixing Console

A sound engineer at a music company faces a challenge. The output from their newly acquired studio&#x27;s vintage mixing console is insufficient for modern recording equipment.To resolve this, the engineer needs to design an audio pre-amplifier using an operational amplifier, to boost the signal level.The pre-amplifier should amplify the audio signal by a factor of 10, have an input impedance above ten kilo-ohms to prevent console overloading, and cover the entire audio spectrum from 20Hz to 20kHz.The op-amp model 741 is chosen because it can handle the required frequency range without significant gain loss.The engineer uses the non-inverting operational amplifier configuration to meet the requirement of a gain of 10 and high input impedance.The gain of a non-inverting amplifier equals one plus the ratio of the feedback resistor to the resistor connected to the inverting input.To achieve a gain of 10, a 180-kilo-ohm feedback resistor and a 20-kilo-ohm input resistor are selected.This design effectively boosts the console&#x27;s output, enabling it to drive the digital recording equipment.

design example: vintage mixing console

A sound engineer at a music company recently encountered a problem. The output from their newly acquired studio&#x27;s vintage mixing console was too low for the requirements of modern recording equipment. To rectify this situation, the engineer decided to design an audio pre-amplifier using an operational amplifier (op-amp) to boost the signal level.
The specifications for the pre-amplifier were clear. It needed to amplify the audio signal by a factor of 10, have an input impedance above 10 kilo-ohms to prevent overloading the console, and be capable of covering the entire audio spectrum from 20 Hz to 20 kHz.
The engineer chose the op-amp model 741, a popular choice in audio applications due to its ability to handle the required frequency range without significant gain loss. This model would ensure that the pre-amplifier could adequately amplify the signals across the whole audio spectrum.
To meet the requirement of a gain of 10 and high input impedance, the engineer decided to use the non-inverting operational amplifier configuration. The gain of a non-inverting amplifier equals one plus the ratio of the feedback resistor to the resistor connected to the inverting input.
To achieve the desired gain of 10, the engineer selected a 100 kilo-ohms feedback resistor and a 10 kilo-ohms input resistor. This combination would provide the necessary amplification while maintaining an adequate input impedance to prevent overloading the mixing console.
This carefully designed pre-amplifier effectively boosted the console&#x27;s output, enabling it to drive the digital recording equipment successfully. The result was a seamless integration of vintage and modern equipment, ensuring the preservation of the unique sound qualities of the vintage console while taking advantage of the capabilities of contemporary digital recording technology.

A sound engineer at a music company faces a challenge. The output from their studio&#x27;s newly acquired vintage mixing console is insufficient for modern ...

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Education

JoVE Core

Electrical Engineering

Unit 1

Operational Amplifiers

KEY TERMS AND CONCEPTS

Learn by watching this video about Design Example: Vintage Mixing Console at JoVE.com

op-amp preamp for a vintage console

A sound engineer designs an op-amp pre-amplifier for a vintage mixing console. The console’s output is too low for modern recording equipment, so the signal must be boosted before it can be used. The goal is to build a preamp that raises the audio level without changing the console’s character.

The design must meet three clear requirements. It needs a gain of 10, an input impedance above 10 kilo-ohms so the console is not overloaded, and a frequency range that covers the full audio spectrum from 20 Hz to 20 kHz. To meet these needs, the engineer chooses the 741 operational amplifier, which can handle this frequency range without a significant loss in gain.

The circuit uses a non-inverting op-amp configuration. In this setup, the gain equals one plus the ratio of the feedback resistor to the resistor connected to the inverting input. The engineer selects a 100 kilo-ohms feedback resistor and a 10 kilo-ohms input resistor to reach the target gain of 10.

This choice also helps keep the input impedance high enough for the vintage console. The pre-amplifier then boosts the console output so it can drive digital recording equipment successfully. The result is a smooth link between vintage gear and modern recording technology.

Op-Amp Preamp for a Vintage Console

operational amplifiers

Operational Amplifier Pinout and Signal Use

An operational amplifier, or op-amp, is a flexible circuit building block used in many electronic designs. It can act like a voltage-controlled voltage source, and it can also be used to create a voltage- or current-controlled current source. When resistors and capacitors are connected to its terminals, an op-amp can perform mathematical operations on signals. Op-amps are able to sum signals, amplify a signal, integrate it, or differentiate it. These features make them useful in practical...

characteristics of opamp

Op-Amp Gain, Feedback, and Saturation

An operational amplifier, or op-amp, is an electronic circuit component used with other circuit parts to carry out a signal-processing task. It is often described with an equivalent circuit model. In that model, the output section includes a voltage-controlled source in parallel with the output resistance, R o. The model also shows the input resistance, R i, which is the Thevenin equivalent resistance seen at the input terminals. The differential input voltage, v d, is the difference between...

A sound engineer designs an op-amp pre-amplifier for a vintage mixing console. The console’s output is too low for modern recording equipment, so the signal must be boosted before it can be used. The goal is to build a preamp that raises the audio level without changing the console’s character. The design must meet three clear requirements. It needs a gain of 10, an input impedance above 10 kilo-ohms so the console is not overloaded, and a frequency range that covers the full audio spectrum...

inverting and non-inverting opamps

Op-Amp Gain: Inverting, Noninverting, Buffer

Operational amplifiers can be used as inverting, noninverting, and buffer amplifiers. In these circuits, the output voltage depends on the input voltage and the resistor setup around the op-amp. In an inverting amplifier, the input voltage is sent through a resistor to the inverting terminal. The non-inverting terminal is grounded, and a feedback resistor links the inverting terminal to the output. Using Kirchhoff's Current Law and an ideal op-amp model, the gain can be found. This circuit...

sum and difference opamps

Op-Amp Adders and Subtractors

Operational amplifiers can be wired to add or subtract signals. In these two op-amp setups, the summing amplifier combines several input signals into one output, while the difference amplifier compares two inputs and amplifies their difference. A summing amplifier is also called an adder. Input signals, such as audio signals, enter through input resistors. These resistors send currents through the feedback resistor, which produces an output voltage. Using Kirchhoff's current law and Ohm's Law,...

characteristics of practical op amps

Op Amp Noise Rejection and Buffering

Practical op amps are used to separate useful signals from unwanted noise. A difference amplifier should ideally amplify only the difference between two input signals. In real circuits, though, the output depends on both differential gain and common-mode gain. The common-mode rejection ratio, or CMRR, measures how well an op amp rejects common-mode signals. Common-mode signals are the same on both inputs. A higher CMRR helps an op amp ignore noise and amplify the wanted signal, such as music...

integrator and differentiator

Op-Amp Circuits in Cruise Control

Op-amp circuits are used in cruise control systems to help cars keep a constant speed. In these systems, operational amplifiers, or op-amps, can work as integrators and differentiators. Both circuits use resistors and capacitors, which makes them compact and cost-effective. An integrator circuit produces an output that is proportional to the integral of the input signal. It is made by replacing the feedback resistor in a standard inverting amplifier with a capacitor. The output and input...

cascaded op amps

Op Amp Stages in Series

Operational amplifiers can be connected in series as separate stages. This cascade works because op-amps have very high input resistance and very low output resistance. Those properties help each stage keep its input-output relationship while driving the next stage. In a cascaded op-amp circuit, the output of one stage becomes the input of the next. Each stage adds gain to the signal as it passes through. The overall gain is the product of the gain of each stage. This design can improve...

instrumentation amplifier

ECG Signal Amplifier Design

An ECG signal amplifier helps an electrocardiography machine measure the heart’s electrical activity. ECG electrodes detect tiny voltage changes on the skin that come from depolarization of the heart muscle during each heartbeat. These signals are in the microvolt range, so they can be easily hidden by noise or interference. To solve this problem, ECG machines use an instrumentation amplifier. This amplifier boosts the ECG waveform while reducing common-mode noise, which is interference that...

key terms and concepts

See how a non-inverting 741 op-amp preamplifier boosts a vintage mixing console signal to match modern recording gear across the audio range.

Op-Amp Preamp for a Vintage Console | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

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Ask questions and define problems related to specialized topics of study based on observations or information from text, phenomena, models, or investigations;

112.51.c.1.A.

Scientific Method

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Apply science practices related to specialized topics of study to plan and conduct investigations or use engineering practices to design solutions to problems;

112.51.c.1.B.

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112.51.c.1.C.

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112.51.c.1.D.

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112.51.c.1.E.

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112.51.c.1.F.

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112.51.c.2.C.

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Op-Amp Preamp for a Vintage Console

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