18W Class-B Audio Amplifier with Tone Controls

18W Class-B Audio Amplifier with Tone Controls

18W Class-B Audio Amplifier with Tone Controls

General Description for 18W Class-B Audio Amplifier with Tone Controls

The particular circuit configuration, allowed to push the NE5534 exceptional capacity of driving the output transistors near to its limits, enabling the whole amplifier to deliver relatively high power outputs without problems. Despite the complication added by the tone controls, the amplifier has an input sensitivity of 130mV RMS, allowing to connect directly to its input the most disparate audio sources without the need for a separate preamplifier. For this reason, it was possible to obtain 18W into an 8 Ohm load using a power supply voltage of +/- 20V. In order to satisfy repeated requests by correspondents, a medium power audio amplifier incorporating tone controls in the feedback path was finally designed.Total Harmonic Distortion figures are astonishingly low, much lower than comparable audio amplifiers using a single-IC audio amp. To avoid an excessive increase in parts-count, due to the addition of the tone controls, a simple amplifier circuitry was designed on the same guidelines of the successful 45 Watt Class B Amplifier, but using the excellent NE5534 IC instead of a discrete component op-amp to drive the output "dumper" transistors. An interesting feature of this amplifier is the absence of any kind of setup.

Parts for 18W Class-B Audio Amplifier with Tone Controls

P1______________50K  Log. Potentiometer (or 47K)
                     (twin concentric-spindle dual gang for stereo)
P2______________20K  Linear Potentiometer (or 22K)
                     (twin concentric-spindle dual gang for stereo)
P3_____________100K  Linear Potentiometer
                   (twin concentric-spindle dual gang for stereo)
R1_____________820R  1/4W Resistor
R2______________68R  1/4W Resistor
R3_______________1K8 1/4W Resistor
R4______________10K  1/4W Resistor
R5_______________1K  1/4W Resistor
R6,R7__________100R  1/4W Resistors
R8_____________330R  1/4W Resistor
R9______________47R  1/2W Resistor
C1_______________1µF  63V Polyester Capacitor
C2______________33pF  63V Polystyrene or Ceramic Capacitor
C3______________10nF  63V Polyester Capacitor
C4,C5____________1nF  63V Polyester Capacitors
C6_____________120nF  63V Polyester Capacitor
C7______________22nF  63V Polyester Capacitor
C8,C10_________220nF  63V Polyester Capacitors
C9______________22µF  25V Electrolytic Capacitor
C11,C12________220µF  25V Electrolytic Capacitors
IC1__________NE5534   Low noise Single Op-amp
Q1____________BD440   60V 4A PNP Transistor
Q2____________BD439   60V 4A NPN Transistor
J1______________RCA audio input socket

Perpetuum mobile STEAM ENGINE made of glass

Electronics Tutorial #1 - Electricity - Voltage, Current, Power, AC and DC

Basic / beginners Electronics Tutorial / course / lesson - Voltage, Current, Power, AC and DC
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Nikola Tesla - http://en.wikipedia.org/wiki/Nikola_T...
Thomas Edison - http://en.wikipedia.org/wiki/Thomas_E...

In this tutorial I cover the following:

* Some history about electricity / central power stations / electrification. 
* Science of electron flow in a conductor / wire
* I use fluid dynamics in a pipe to explain voltage (pressure), current in Amps (flow) and consumption in Amp hours (rate of flow).
* We look at AC (alternating current) and DC (direct current) on the UNI-T UT81B scopemeter
* We look at how voltage / pressure is required to charge a 12 volt battery
* What is electricity? / How does electricity work?

Topics for future videos in this series:

* Ohms law, resistance, power, energy
* Electronic components - diodes, transistors, FETS, capacitors, digital logic gates, integrated circuits, 555 timer.
* Series and parallel circuits
* Op amps and feedback

Power Amplifier with voltage regulator 4 × 50 Watt TDA8588

Power Amplifier with voltage regulator 4 × 50 Watt TDA8588

   The TDA8588 is a multiple voltage regulator combined with four independent audio power amplifiers configured in bridge tied load with diagnostic capability. The output voltages of all regulators except regulators 2 and 3 can be controlled via the I2C-bus. However, regulator 3 can be set to 0 V via the I2C-bus. The output voltage of regulator 2 (microcontroller supply) and the maximum output voltage of regulator 3 (mechanical digital and microcontroller supplies) can both be either 5 V or 3.3 V depending on the type number. The maximum output voltages of both regulators are fixed to avoid any risk of damaging the microcontroller that may occur during a disturbance of the I 2C-bus. The amplifier diagnostic functions give information about output offset, load, or short-circuit. Diagnostic functions are controlled via the I2C-bus. The TDA8588 is protected against short-circuit, over-temperature, open ground and open VP connections. If a short-circuit occurs at the input or output of a single amplifier, that channel shuts down, and the other channels continue to operate normally. The channel that has a short-circuit can be disabled by the microcontroller via the appropriate enable bit of the I 2C-bus to prevent any noise generated by the fault condition from being heard.

Speaker protection

    If one side of a speaker is connected to ground, a missing current protection is implemented to prevent damage to the speaker. A fault condition is detected in a channel when there is a mismatch between the power current in the high side and the power current in the low side; during a fault condition the channel will be switched off. The load status of each channel can be read via the I 2C-bus: short to ground (one side of the speaker connected to ground), short to VP (one side of the speaker connected to VP), and shorted load.

Muting 

    A hard mute and a soft mute can both be performed via the I 2C-bus. A hard mute mutes the amplifier within 0.5 ms. A soft mute mutes the amplifier within 20 ms and is less audible. A hard mute is also activated if a voltage of 8 V is applied to pin STB. 

Temperature protection 

     If the average junction temperature rises to a temperature value that has been set via the I2C-bus, a thermal protection pre-warning is activated making pin DIAG LOW. If the temperature continues to rise, all four channels will be muted to reduce the output power (soft thermal clipping). The value at which the temperature mute control activates is fixed; only the temperature at which the thermal protection pre-warning signal occurs can be specified by bit D4 in instruction byte 3. If implementing the temperature mute control does not reduce the average junction temperature, all the power stages will be switched off (muted) at the absolute maximum temperature Tj(max)

Power Amplifier with voltage regulator 4 × 50 Watt TDA8588

60W MosFet Audio Amplifier

High Quality, powerful unit: 90W into 4 Ohm load Also suited as guitar or bass amplifier

60W MosFet Audio Amplifier

60W MosFet Audio Amplifier Description

To celebrate the hundredth design posted to this website, and to fulfil the requests of many correspondents wanting an amplifier more powerful than the 25W MosFet, a 60 - 90W High Quality power amplifier design is presented here.

Circuit topology is about the same of the above mentioned amplifier, but the extremely rugged IRFP240 and IRFP9240 MosFet devices are used as the output pair, and well renowned high voltage Motorola's transistors are employed in the preceding stages.

The supply rails voltage was kept prudentially at the rather low value of + and - 40V. For those wishing to experiment, the supply rails voltage could be raised to + and - 50V maximum, allowing the amplifier to approach the 100W into 8 Ohm target: enjoy!

A matching, discrete components, Modular Preamplifier design is available here:Modular Audio Preamplifier.

Notes:

• In the original circuit, a three-diode string was wired in series to R10. Two of these diodes are now replaced by a red LED in order to achieve improved quiescent current stability over a larger temperature range. Thanks to David Edwards of LedeAudio for this suggestion.
• A small, U-shaped heatsink must be fitted to Q6 & Q7.
• Q8 & Q9 must be mounted on large heatsinks.
• Quiescent current can be measured by means of an Avo-meter wired in series to the positive supply rail and no input signal.
• Set the Trimmer R10 to its minimum resistance.
• Power-on the amplifier and adjust R10 to read a current drawing of about 120 - 130mA.
• Wait about 15 minutes, watch if the current is varying and readjust if necessary.
• The value suggested for C1 and C2 in the Power Supply Parts List is the minimum required for a mono amplifier. For optimum performance and in stereo configurations, this value should be increased: 10000µF is a good compromise.
• A correct grounding is very important to eliminate hum and ground loops. Connect to the same point the ground sides of R1, R3, C2, C3 and C4 and the ground input wire. Connect R7 and C7 to C11 to output ground. Then connect separately the input and output grounds to the power supply ground.

Parts:

R1______________47K   1/4W Resistor
R2_______________4K7  1/4W Resistor
R3______________22K   1/4W Resistor
R4_______________1K   1/4W Resistor
R5,R12,R13_____330R   1/4W Resistors
R6_______________1K5  1/4W Resistor
R7______________15K   1/4W Resistor
R8______________33K   1/4W Resistor
R9_____________150K   1/4W Resistor
R10____________500R   1/2W Trimmer Cermet
R11_____________39R   1/4W Resistor
R14,R15___________R33 2.5W Resistors
R16_____________10R   2.5W Resistor
R17_______________R22   5W Resistor (wirewound)

C1_____________470nF   63V Polyester Capacitor
C2_____________470pF   63V Polystyrene or ceramic Capacitor
C3______________47µF   63V Electrolytic Capacitor
C4,C8,C9,C11___100nF   63V Polyester Capacitors
C5______________10pF   63V Polystyrene or ceramic Capacitor
C6_______________1µF   63V Polyester Capacitor
C7,C10_________100µF   63V Electrolytic Capacitors

D1___________1N4002   100V 1A Diode
D2_____________5mm. Red LED

Q1,Q2,Q4_____MPSA43   200V 500mA NPN Transistors
Q3,Q5________BC546     65V 100mA NPN Transistors
Q6___________MJE340   200V 500mA NPN Transistor
Q7___________MJE350   200V 500mA PNP Transistor
Q8___________IRFP240  200V 20A N-Channel Hexfet Transistor
Q9___________IRFP9240 200V 12A P-Channel Hexfet Transistor

45 Watt Class B Amplifier

45 Watt Class B Amplifier Description

45W into 8 Ohm - 69W into 4 Ohm Easy to build - No setup required

45 Watt Class B Amplifier

45 Watt Class B Amplifier Description

The main design targets for this amplifier were as follows:

• Output power in the 40 - 70W range
• Simple circuitry
• Easy to locate, low cost components
• Rugged performance
• No setup

These goals were achieved by using a discrete-components op-amp driving a BJT complementary common-emitter output stage into Class B operation. In this way, for small output currents, the output transistors are turned off, and the op-amp provides all of the output current. At higher output currents, the power transistors conduct, and the contribution of the op-amp is limited to approximately 0.7/R11. The quiescent current of the op-amp biases the external transistors, and hence greatly reduces the range of crossover.

The idea sprang up from a letter published on Wireless World, December 1982, page 65 written by N. M. Allinson, then at the University of Keele, Staffordshire.
In this letter, op-amp ICs were intended as drivers but, as supply voltages up to +/- 35V are required for an amplifier of about 50W, the use of an op-amp made of discrete-components was then considered and the choice proved rewarding.

The discrete-components op-amp is based on a Douglas Self design. Nevertheless, his circuit featured quite obviously a Class A output stage. As for proper operation of this amplifier a Class B output stage op-amp is required, the original circuit was modified accordingly.

Using a mains transformer with a secondary winding rated at the common value of 25 + 25V (or 24 + 24V) and 100/120VA power, two amplifiers can be driven at 45W and 69W output power into 8 and 4 Ohms respectively, with very low distortion (less than 0.01% @ 1kHz and 20W into 8 Ohms).

This simple, straightforward but rugged circuit, though intended for any high quality audio application and, above all, to complete the recently started series of articles forming the Modular Preamplifier Control Center, is also well suited to make a very good Guitar or Bass amplifier. Enjoy!
Notes:
2N3055 and MJ2955 transistors were listed for Q8 and Q9 as the preferred types, but many different output transistors can be used satisfactorily: TIP3055/TIP2955, TIP35/TIP36, MJ802/MJ4502 amongst others.
Discrete op-amp output transistors Q6 and Q7 do not require any heatsink as their cases remain at ambient temperature. Power transistors Q8 and Q9 should be mounted on a black, finned heatsink as usual.

Parts:

R1______________18K  1/4W Resistor
R2_______________3K9 1/4W Resistor
R3,R6____________1K  1/4W Resistors
R4_______________2K2 1/4W Resistor
R5______________15K  1/4W Resistor
R7______________22K  1/4W Resistor
R8_____________330R  1/4W Resistor
R9,R10__________10R  1/4W Resistors
R11,R12_________47R  1/4W Resistors
R13_____________10R    1W Resistor


C1_______________1µF  63V Polyester Capacitor
C2_____________470pF  63V Polystyrene or Ceramic Capacitor
C3______________47µF  25V Electrolytic Capacitor
C4______________15pF  63V Polystyrene or Ceramic Capacitor
C5_____________220nF 100V Polyester Capacitor
C6_____________100nF  63V Polyester Capacitor

D1,D2,D3,D4___1N4148  75V 150mA Diodes

Q1,Q2________BC560C   45V 100mA Low noise High gain PNP Transistors
Q3,Q4________BC556    65V 100mA PNP Transistors
Q5___________BC546    65V 100mA NPN Transistor
Q6___________BD139    80V 1.5A NPN Transistor
Q7___________BD140    80V 1.5A PNP Transistor
Q8__________MJ2955    60V 15A PNP Transistor
Q9__________2N3055    60V 15A NPN Transistor

18W Class-B Audio Amplifier with Tone Controls

18W Class-B Audio Amplifier with Tone Controls

18W Class-B Audio Amplifier with Tone Controls

In order to satisfy repeated requests by correspondents, a medium power audio amplifier incorporating tone controls in the feedback path was finally designed.

To avoid an excessive increase in parts-count, due to the addition of the tone controls, a simple amplifier circuitry was designed on the same guidelines of the successful 45 Watt Class B Amplifier, but using the excellent NE5534 IC instead of a discrete component op-amp to drive the output "dumper" transistors.

The particular circuit configuration, allowed to push the NE5534 exceptional capacity of driving the output transistors near to its limits, enabling the whole amplifier to deliver relatively high power outputs without problems. For this reason, it was possible to obtain 18W into an 8 Ohm load using a power supply voltage of +/- 20V.

Despite the complication added by the tone controls, the amplifier has an input sensitivity of 130mV RMS, allowing to connect directly to its input the most disparate audio sources without the need for a separate preamplifier.

Total Harmonic Distortion figures are astonishingly low, much lower than comparable audio amplifiers using a single-IC audio amp.

An interesting feature of this amplifier is the absence of any kind of setup.

The power supply is straightforward. The parts values suggested are suited to power a stereo version of this design. For a mono amplifier a less powerful mains transformer can be used, having a 30V Center-tapped or 15 + 15V secondary winding, rated at about 24 to 30VA or 0.8-1A.

Notes:

Q1 and Q2 power transistors should be mounted on a finned heatsink of at least 100x50x25mm.

+ and - 22V is the absolute maximum permissible voltage supply for NE5534: please do not exceed this limit.

In the event you obtain a higher voltage from your power supply, you can consider the use of a regulated supply. Please see Simple, Efficient, Regulated Power Supply.

Parts:

P1______________50K  Log. Potentiometer (or 47K)
                     (twin concentric-spindle dual gang for stereo)
P2______________20K  Linear Potentiometer (or 22K)
                     (twin concentric-spindle dual gang for stereo)
P3_____________100K  Linear Potentiometer
                     (twin concentric-spindle dual gang for stereo)

R1_____________820R  1/4W Resistor
R2______________68R  1/4W Resistor
R3_______________1K8 1/4W Resistor
R4______________10K  1/4W Resistor
R5_______________1K  1/4W Resistor
R6,R7__________100R  1/4W Resistors
R8_____________330R  1/4W Resistor
R9______________47R  1/2W Resistor

C1_______________1µF  63V Polyester Capacitor
C2______________33pF  63V Polystyrene or Ceramic Capacitor
C3______________10nF  63V Polyester Capacitor
C4,C5____________1nF  63V Polyester Capacitors
C6_____________120nF  63V Polyester Capacitor
C7______________22nF  63V Polyester Capacitor
C8,C10_________220nF  63V Polyester Capacitors
C9______________22µF  25V Electrolytic Capacitor
C11,C12________220µF  25V Electrolytic Capacitors

IC1__________NE5534   Low noise Single Op-amp

Q1____________BD440   60V 4A PNP Transistor
Q2____________BD439   60V 4A NPN Transistor

J1______________RCA audio input socket