Audio Tone Control Using The TLC074 Operational Amplifier

Audio Tone Control Using The TLC074 Operational Amplifier

Posted by: Claire

On: 25 Jul, 2014

Viewed:1,116 times - 1 hour, 8 minute, 20 second ago

Downloaded: 1 times - 5 year, 143 day, 11 hour, 35 minute, 32 second ago

Category: Audio

Audio Tone Control Using The TLC074 Operational Amplifier Rating:
4
83 out of 100 based on 322 user ratings

Are you want to make audio tone control? In this time i want to write about audio tone control using TLC074 like on title above. The design and function of a stereo high-fidelity tone controlusing a single TLC074 quad operational amplifier. A rail...

Are you want to make audio tone control? In this time i want to write about audio tone control using TLC074 like on title above. The design and function of a stereo high-fidelity tone controlusing a single TLC074 quad operational amplifier. A rail-to-rail operational amplifier is used to provide a midpoint supply voltage and signal ground, allowing the use of a single powersupply.

1. Introduction

Tone controls allow the frequency response of the audio system to be adjustedto compensate for the response of speakers and their enclosures or the listeningroom, or to simply provide a more pleasing sound.In this design, a variation of the classic and very popular Baxandall1, negativefeedback tone control circuit provides the familiar Hi-Fi tone control withcut...flat...boost response for both bass and treble frequencies. A single basscontrol adjusts both channels simultaneously and a single treble control adjustsboth channels.A pair of slide pots adjusts the volume of each channel independently. The circuitprovides a gain of 6 dB at the maximum volume setting when both tone controlsare at their midpoints (flat).

2. Circuit Description

Each of the two separate channels of the tone control circuit is basically an activefilter built around an IC operational amplifier. An active filter design was chosenover a passive filter circuit because active filters have the frequency-responseadjusting components located in the feedback loop of the filter amplifiers,providing much lower THD, little or no insertion loss, and a symmetrical responseabout the axis in both boost and cut, compared with most passive designs. Eachchannel also includes an input buffer amplifier to provide some gain and isolationfrom source impedance variations.A block diagram of the right channel of the tone control circuit is shown inFigure 1. The left channel is identical.

audio tone control using the tlc074 operational amplifier 1.jpg

One dual-element slide pot adjusts the bass response from approximately–20 dB of cut, to flat, to approximately 20 dB of boost for both channelssimultaneously. Another dual-element slide pot adjusts the treble response ofboth channels through the same range.Mid-range frequencies are not affected by the tone controls. An overall flatresponse (no boost or cut at frequency extremes) is obtained when the tonecontrols are at their mid-point position.The composite frequency response range curves shown in Figure 2 are providedby the component values indicated in the schematic (Figure 3).

audio tone control using the tlc074 operational amplifier 2.jpg

A single TLC074 quad operational amplifier IC contains all the amplifiers requiredfor buffering and filtering both left and right channels. A TLV2461 operationalamplifier IC is connected to provide a virtual ground for proper operation of theTLC074 from a single supply voltage.

Figure 3 shows the tone control schematic diagram.

audio tone control using the tlc074 operational amplifier 3.jpg

The input buffer amplifier provides a gain of approximately 2 (RF/RIN) with thespecified resistor values. Input capacitor C1 blocks dc and sets the minimumlow-frequency response of the tone control circuit at approximately 16 Hz (–3 dB)with the value of 2.2 μF. Volume control R1 has an audio taper to provide aperceived linear response in volume, proportional to the physical position of theslider. The adjustment range of the buffer amplifier is from 0 V to approximately2 times (6 dB) the audio signal input voltage.

The tone adjusting action in each channel of the tone control circuit is providedby an equalizing amplifier (or active filter) created by placing afrequency-dependent negative feedback network around an operationalamplifier. Almost any overall gain-versus-frequency characteristic can be definedby the design of the feedback network.

3. Tone Control Frequency Response

The overall tone control circuit frequency response can be shifted up or down bychanging the values of capacitors C7, C9, C11, and C12 in the tone adjustingnetworks.To shift the frequency response downward, for example, increase the values ofthe capacitors in the tone adjusting networks. Doubling the values of C7, C9, C11,and C12 shifts the break frequency downward a full octave (Case B, Figure 4).Conversely, halving the values of C7, C9, C11, and C12 shifts the breakfrequency upward a full octave. (1 octave up = ½Cx and 1 octave down = 2 Cx.)

audio tone control using the tlc074 operational amplifier 4.jpg

Note that to keep the boost and cut break frequencies the same, the value of C7must equal that of C9, and the value of C11 must equal that of C12. In addition,although the bass and treble break frequencies can be adjusted separately ifdesired, to maintain the overall shape and symmetry of the response, all fourcapacitors must be increased or decreased by the same factor.

Figures 5, 6, and 7 are measurements from the TI Tone Control EVM (SLOP109),using the TLC074 IC amplifier. All measurements taken with Vdd = 5 V, Vin =100 mVrms, RL = 47 kΩ, and f = 3 kHz.

audio tone control using the tlc074 operational amplifier 5.jpg

audio tone control using the tlc074 operational amplifier 6.jpg

audio tone control using the tlc074 operational amplifier 7.jpg

4. Summary

The familiar Baxandall Hi-Fi tone control is updated from vacuum tubes withmodern high-performance operational amplifiers. Two channels (for stereo) canbe implemented using only two very small IC packages and a few small passivecomponents. This design places the frequency determining components in thefeedback loop of an operational amplifier, reducing distortion and insertion loss,and providing symmetrical boost and cut responses.

Keywords related to Tone control circuit #passive tone control circuit #active tone control circuit #tone control circuit using 4558 #tone control circuit using transistor #bass mid treble tone control circuit pdf #3 band tone control circuit #lm358 tone control circuit #simple tone control

Related Posts

Motorola Hi Fi Power Amplifier Electronic Circuit Diagram

This is a very simple, low cost, Hi-Fi quality power amplifier. You can build it 5 ways, like it’s shown in the table (from 20 W to 80 W RMS).

  • The first thing that you must do, is t...

Amplified Ear Electronic Circuit Diagram

This circuit, connected with 32 Ohms impedance mini-earphones, can detect very remote sounds. Useful for theatre, cinema and lecture goers: every word will be clearly heard. You can also listen to ...

Fet Audio Mixer Electronic Circuit Diagram

How to build FET Audio Mixer

This simple circuit mixes two or more channels into one channel (eg. stereo into mono). The circuit can mix as many or as few channels as you ...

25W Mosfet Audio Amplifier Electronic Circuit Diagram

This is high fidelity, high quality 25W HiFi audio amplifier circuit delivers great audio performance. You don’t need pre amplifier circuit for this design since it can be directly connected ...

Amplifier Timer Electronic Circuit Diagram

This circuit turns-off an amplifier or any other device when a low level audio signal fed to its input is absent for 15 minutes at least.
Pushing P1 the device is switched-on feeding any appli...

Portable Headphone Amplifier Electronic Circuit Diagram

Portable Headphone Amplifier Circuit Based 3 Transistors

his simple headphone amplifier circuit can be directly connected to other compact devices such as CD player, W...

As the fastest growing demand of circuit and wiring diagram for automotive and electronics on internet based on different uses such as electronic hobbyists, students, technicians and engineers than we decided to provide free circuit and wiring diagram base on your needed.

To find circuit and wiring diagram now a day its easy. E-learning through internet as a right place to search an exact circuit and wiring diagram of your choice and it's much fun and knowledgable. On internet you will find thousands of electronic circuit diagrams some are very good designed and some are not. So you have to modify them to make them according to your needs but some circuits are ready to make and require no changes.

There are many categories of circuit and wiring diagrams like automotive, audio circuits, radio & RF circuits, power supply circuits, light circuits, telephone circuits, timer circuits, battery charger circuits etc. There are many types of circuit and wiring diagrams some are very easy to build and some are very complicated, some are so small and some contain huge list of parts.

We provides free best quality and good designed schematic diagrams our diagrams are free to use for all electronic hobbyists, students, technicians and engineers. We also provides a full educational system to students new to electronics. If you are new to electronics you are a student or a electronic hobbyist and want to increase your knowledge in electronics or want to understand electronics in a very easy way so this is the right place for you we provide electronics beginner guide tutorials to easily understand complicated electronic theory. Our mission is to help students and professionals in their field.