Stereo Tone Control Component List

INTEGRATED CIRCUIT

• TL072 : 2
• TL071 : 1

RESISTORS All 1/4W

• 22K ohm (red, red, orange) : 10
• 10K ohm (Brown, Black, Orange) : 10
• 1K ohm (brown, black, red) : 3
• 100K ohm (brown, black, orange) : 3
• 100 ohm (Coffee, Black, Coffee) : 4
• stereo/dual potentiometers 100K ohm : 3
• stereo/dual potentiometers 10K ohm : 2
• mono/single potentiometers 10K ohm : 2

CAPACITORS

• 1uF/25V electrolytic capacitor : 4
• 10uF/25V electrolytic capacitor : 1
• 4.7uF/25V electrolytic capacitor : 2
• 6.8nF (682) polyester capacitor : 2
• 1.5nF (152) polyester capacitor : 2
• 47nF (473) polyester capacitor : 2
• 1nF (102) polyester capacitor : 2
• 100nF (104) polyester capacitor : 4
• 2200uF x 25 V electrolytic capacitor : 2
• 1uF nonpolar capacitor (105) : 5

Stereo Tone Control PCB Layout and Component Placement

Power Supply Circuit

The power supply type for the stereo tone control is symmetrical and regulated and on its output we use +15 and -15 VDC. The LM7815 will deliver stabilized +15VDC and the LM7915 will deliver stabilized -15 VDC. For symmetrical source, the TL072 VCC range will be 7V up to 36V, so you may use a pair of regulator IC LM7805/LM7905 up to LM7815/7915.
Below is the schematic diagram, pcb design and component layout:

Schematic Diagram 4in1: 100W RMS Power Amplifier With VU, Power Supply and Tone Control

Part Lists

Active Components

• IC TDA 7294 : 1
• IC 7812 : 1
• IC LM3914 : 1
• Diode Zener 12V : 2
• IC 4558 : 1
• Diode 1N4148 : 1
• Rectifier Bridge Diode 6 A : 1
• LED : 11

Resistors

• 390 Ω – 1/4w : 1
• 680 Ω – 1/4w : 1
• 1K Ohm – 1/4w : 2
• 2k2 Ohm – 1/4w : 3
• 2k7 Ohm – 1/4w : 1
• 3k3 Ohm – 1/4w : 1
• 5k6 Ohm – 1/4w : 1
• 8k2 Ohm – 1/4w : 1
• 10K Ohm – 1/4w : 4
• 20K Ohm – 1/4w : 2
• 22K Ohm – 1/4w : 3
• 30K Ohm – 1/4w : 1
• 47k Ohm – 1/4w : 1
• 10R ohm – 1/4w : 1
• 56R Ohm – 2w : 1
• 2K2 Ohm – 2w : 2
• Potensiometer 50K Ohm : 3

Capacitors

• 100pF nonpolar capacitor disc / ceramic : 2
• 6n8F nonpolar polyester capacitor : 2
• 10nF nonpolar polyester capacitor : 2
• 100nF nonpolar polyester capacitor : 6
• 220nF nonpolar polyester capacitor : 1
• 2.2uF/63V electrolytic capacitor : 1
• 10uF/63V electrolytic capacitor : 5
• 22uF/63v electrolytic capacitor : 2
• 100uF/63V electrolytic capacitor : 2
• 4700uF/63V electrolytic capacitor : 2

100W RMS Power Amplifier PCB Layout

Component Placement

This is a single channel (mono) audio system. For stereo audio system, you need two similar circuit and make some changes such as: use higher transformer current, higher diode current, higher capacitor value for the power supply module. Use only one power supply. Use stereo potensiometer and connect to the two boards using cable.

Here is the circuit diagram of stereo digital volume control. This circuit could possibly be applied for upgrading your manual volume management within a stereo amplifier circuit. In this particular circuit, push-to-on switch S1 controls the forward (volume enhance) operation of the two channels while a identical switch S2 controls reverse (volume reduce) operation of the two channels.

In this digital volume control circuit, the IC1 timer 555 is set up as an astable flip-flop to deliver low-frequency pulses to up/down clock input pins of pre-setable up/down counter 74LS193 (IC2) through push-to-on switches S1 and S2. To adjust the pulse width of pulses from IC1, you may possibly replace the timing resistor R1 by using a variable resistor.

Operation of switch S1 (up) triggers the binary output to increment while operation of S2 (down) triggers the binary output to decrement. The highest count being 15 (all outputs logic 1) and lowest count being 0 (all outputs logic 0), it outcomes in highest and lowest volume respectively.

The active high outputs A, B, C and D of the counter are utilized for controlling two quad bi-polar analogue switches in each of the two CD4066 ICs (IC3 and IC4). The two of the output bits, when high, short a part of the resistor network comprising series resistors R6 thru R9 for one channel and R10 thru R13 for the other channel, and thus manage the output of the audio signals being fed towards the inputs of stereo amplifier circuit module. Push-to-on switch S3 is utilized for resetting the output of counter to 0000, and thus turning the volume of both of those channels to the lowest level.

Transistor type: Q1 – ztx384 ; Q2 – BC415p
The circuit’s peaks frequencies is at 5000 Hz for a cleaner and more penetrating sound.

Tone booster is the “fix” version of tone control circuit. Tone control is a type of equalization used to make specific pitches or “frequencies” in an audio signal softer or louder. A tone control circuit is an electronic circuit that consists of a network of filters which modify the signal before it is fed to speakers, headphones or recording devices by way of an amplifier.

Tone control allows listeners to adjust sound to their liking. It also enables them to compensate for recording deficiencies, hearing impairments, room acoustics or shortcomings with playback equipment. For example, older people with hearing problems may want to increase the loudness of high pitch sounds they have difficulty hearing.

Tone control is also used to adjust an audio signal during recording. For instance, if the acoustics of the recording site cause it to absorb some frequencies more than others, tone control can be used to amplify or “boost” the frequencies the room dampens.

Download Tone Booster circuit in PDF file:

Tone Booster Circuit

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Active Tone Control or ACTOR is an active electronic audio circuit that serves to increase the Loudness (Bass and Treble audio signal), because it uses the Baxandall system. This circuit does not use a potentiometer so that the output audio signal can not be controlled. S1 is used as an option if the circuit is enabled or disabled (bypass).

This circuit works with 12V DC power supply. Above circuit used to be a single channel, for stereo application you need two identical circuit, parallel the supply, and use DPDT switch.

The circuit build based on ordinary tone control circuit, using two low cost transistors FCS9014 in each channel, so there are will be four transistors in this 12v stereo tone control. Take a note that you must connect the circuit before the amplifier module. The output of tone control must be connected to the input of the amplifier. Any small signal NPN transistor such as BC547B, 2N3904, C828, or C945 can be used to replace FCS9014.

There are will be four potensiometers used for this tone control circuit: volume level, bass level, treble level and balance adjustment. For better result, use better components with small tolerance value for example metalfilm resistors, MKM capacitor etc.

This circuit powered with 12V DC power supply, you may use regulated power supply for better performance. Just use regulator IC of LM7812 to get regulated voltage.

Resistance value of resistor R1 is left up to the user depending on gain needs, R2 is unknown – for? experiment purpose. The op-amps are not critical, any standard ones could be used (eq: 741, LM324, etc).

Power supply used for this circuit depends the op-amp IC used. Use the IC datasheet to know the recommended voltage. Some op-amp IC needs symmetrical power supply to work, just find the op-amp which require general power supply (asymmetrical). A regulated power supply will be better for this circuit.

For better sound performance, use high quality component such MKM capacitor (non polar), tantalum capacitor (bipolar), metalfilm resistor, etc.

Download basic tone control circuit in PDF document:

Basic Tone Control Circuit Diagram

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This Hi-Fi tone control circuit can be operated with wide range supply voltage, 12V – 24V DC. Three potensiometers used for sound adjustment: volume level, bass and treble level.

Use good components (such as metalfilm resistors, MKM capacitors, tantalum capacitors, good cable quality) and stabilized/regulated power supply for better sound quality output, of course it will be need more cost.

The quality of components, cabling and power supply will affect the quality of the output.

This is a stereo audio tone control circuit which build based on IC? LM1036. This circuit will controll bass/treble level tone, volume and balance between right channel and left channel (input 1 and 2 ). You may use this circuit for stereo applications such as car radio, TV and audio systems, mp3 player, dvd player, ipod and more. An additional control input allows loudness compensation to be simply effected. The circuit should be works with supply voltage 9V to 15V DC.

Tone control features:

Wide supply voltage range, 9V to 16V
Large volume control range, 75 dB typical
Tone control, ?15 dB typical
Channel separation, 75 dB typical
Low distortion, 0.06% typical for an input level of 0.3 Vrms
High signal to noise, 80 dB typical for an input level of 0.3 Vrms

Schematic diagram:

Pre-Amp + Tone Control Components List:

Resistors:
R1, R2__________________ 220R
R3, R4__________________ 4K7
R5______________________ 2K2
R6______________________ 1K

Capacitors:
C1, 2, 7, 8, 17_________ 10 uF ecap
C3, 4___________________ 47 nF
C5, 6___________________ 15 nF
C9______________________ 220 nF poly
C10_____________________ 100 uF 25V
C11, 12, 13, 14, 16_____ 100 nF
C15_____________________ 1000 uF 35V
C18, 19_________________ 10 nF

Misc.:
IC1_____________________ TDA 1524A
IC2_____________________ LM 7812
P1______________________ 50k linear switch pot
P2, 3, 4________________ 50k linear pot
X1, 2, 3, 4_____________ RCA jack
D1______________________ Diode 1N4004
L1______________________ Red LED

Circuit Works:

All signal processing is done within the TDA1524A by voltage controlled amplifiers and voltage controlled filters. The IC provides a fixed voltage (~ 3.8V DC) at pin 17, and this is used by all the variable resistors to provide an adjustable DC voltage to the appropriate control pins.

Current sensing is used to provide a flat response when R5 is connected to pin 17, and a loudness contour when disconnected. 100 nF capacitors are used on each pot to decouple any AC signals from the control inputs. 10 uF capacitors are used to couple both input and output audio signals whilst blocking DC. R1 and R2, are to ensure stability with capacitive loads. R3 and R4 make sure there are no DC spikes at the output sockets if the load is switched. C3 and C4 control the loudness contour. C5 and C6 control the treble turn-over frequency. C18 and C19 have been added to roll off the gain above 70 kHz. Low volume settings coupled with treble boost was causing HF instability in some instances. This should no longer be a problem.

C15, 16, 17 provide power supply filtering. D1 provides protection in case of incorrect supply polarity. The LED is a power on indicator and may be omitted if not required, or preferably mounted on the enclosure. If you are not using a switch pot, you can connect an external switch across the P1 switch pins, or connect a wire link there and switch the power supply.

The power supply is critical to the noise? performance of the pre-amp. An on board regulator is provided to reduce mains hum. If you wish to use it with a car or other 12V battery, then you should omit the 7812 regulator, and place a wire link between the regulator input and output pin positions on the PC board. Do not short to earth! This will be necessary because the regulator must have an input voltage at least 2-3V greater than it”s output, for it to maintain regulation. However the regulator will not be necessary with a battery supply.

If using a plug pack, it”s output voltage should be 15 to 18V DC. Because most plug packs have poor regulation, one rated at 12V DC will often be around 15V when lightly loaded. The current drain of the pre-amp is less than 50 mA, so many 12 V unregulated supplies may be adequate if you have one. Replace D1 with a wire link if necessary, making sure you have the supply polarity correct!

If you are using a 15-20V supply for your power amplifier, you can use that as your pre-amp supply as well. Make sure you test the voltage first in all cases.

Download the Pre-Amp + Tone Control Circuit Manual in PDF:

Preamp and Tone Control with TDA1524A Manual

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Download TDA1524A Stereo-tone/volume control circuit:

TDA1524A Datasheet

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