Help regarding audio amplifier..

Discussion in 'General Electronics Chat' started by sarang2502, Jan 3, 2010.

  1. sarang2502

    Thread Starter New Member

    Mar 10, 2009
    Hello forum members,

    It would be great if someone helps me out,

    I am having four speakers, 6 ohms and 8W each (Mercury).
    I want to use them in amplifier circuit and play music through my PC/Laptop.
    I have searched many circuits for it. But am totally confused about how much watt output circuit should I use.

    Here are some which I found, please review it and let me know which is suitable, or if anyone has any other idea please suggest me.

    Thanks in advance.

    This audio amplifier project is a class AB audio power amplifier using a TDA2003 module power amplifier. It is easy to construct and has only a few external components. The module is designed with short circuit and thermal protection. It can drive loads as low as 1.6 ohm and is capable of delivering over 10 watts from a 16 V DC power supply.

    The power supply required for is 8 - 18V DC at 1 Amp or more. Maximum output power will only be obtained with a power supply of greater than 1A at 16V DC, and using 2 ohm speakers (or 2 by 4 ohm speakers in parallel). However approximately 4W RMS can be obtained with a 12V DC, 1A supply into a 4 ohm load.

    Audio Amplifier Circuit Diagram


    The major circuitry is contained in the amplifier module. C1 is the input coupling capacitor and blocks DC signal, so does C3 which is the output coupling capacitor, and C2 which blocks DC from the feed back loop to the differential input. R2 and R3 set the level of feed back. C4 and R4 provide a high frequency load for stability where loudspeaker inductive reactance may become excessive. C5 and C6 provide power supply decoupling or filtering.
    There should be no problems with the stability of the circuit, however if you do, make sure the power supply filtering and leads are adequate


    10W Audio Amplifier with Bass-boost
    Circuit diagram:

    P1_________________22K Log.Potentiometer (Dual-gang for stereo)
    P2________________100K Log.Potentiometer (Dual-gang for stereo)
    R1________________820R 1/4W Resistor
    R2,R4,R8____________4K7 1/4W Resistors
    R3________________500R 1/2W Trimmer Cermet
    R5_________________82K 1/4W Resistor
    R6,R7______________47K 1/4W Resistors
    R9_________________10R 1/2W Resistor
    R10__________________R22 4W Resistor (wirewound)

    C1,C8_____________470nF 63V Polyester Capacitor
    C2,C5_____________100µF 25V Electrolytic Capacitors
    C3,C4_____________470µF 25V Electrolytic Capacitors
    C6_________________47pF 63V Ceramic or Polystyrene Capacitor
    C7_________________10nF 63V Polyester Capacitor
    C9________________100nF 63V Polyester Capacitor

    D1______________1N4148 75V 150mA Diode

    IC1_____________NE5532 Low noise Dual Op-amp

    Q1_______________BC547B 45V 100mA NPN Transistor
    Q2_______________BC557B 45V 100mA PNP Transistor
    Q3_______________TIP42A 60V 6A PNP Transistor
    Q4_______________TIP41A 60V 6A NPN Transistor

    J1__________________RCA audio input socket

    This design is based on the 18 Watt Audio Amplifier, and was developed mainly to satisfy the requests of correspondents unable to locate the TLE2141C chip. It uses the widespread NE5532 Dual IC but, obviously, its power output will be comprised in the 9.5 - 11.5W range, as the supply rails cannot exceed ±18V.
    As amplifiers of this kind are frequently used to drive small loudspeaker cabinets, the bass frequency range is rather sacrificed. Therefore a bass-boost control was inserted in the feedback loop of the amplifier, in order to overcome this problem without quality losses.

    • Can be directly connected to CD players, tuners and tape recorders.
    • Schematic shows left channel only, but C3, C4, IC1 and the power
    supply are common to both channels.
    • Numbers in parentheses show IC1 right channel pin connections.
    • A log type for P2 will ensure a more linear regulation of bass-boost.
    • Do not exceed 18 + 18V supply.
    • Q3 and Q4 must be mounted on heatsink.
    • D1 must be in thermal contact with Q1.
    • Quiescent current (best measured with an Avo-meter in series with
    Q3 Emitter) is not critical.
    • Set the volume control to the minimum and R3 to its minimum
    • Power-on the circuit and adjust R3 to read a current drawing of
    about 20 to 25mA.
    • Wait about 15 minutes, watch if the current is varying and readjust
    if necessary.
    • A correct grounding is very important to eliminate hum and ground
    loops. Connect to the same point the ground sides of J1, P1, C2, C3
    &C4. Connect C9 to the output ground.


    18W Audio Amplifier
    Circuit diagram:


    Amplifier parts:
    P1_____________22K Log. Potentiometer (Dual-gang for stereo)

    R1______________1K 1/4W Resistor
    R2______________4K7 1/4W Resistor
    R3____________100R 1/4W Resistor
    R4______________4K7 1/4W Resistor
    R5_____________82K 1/4W Resistor
    R6_____________10R 1/2W Resistor
    R7_______________R22 4W Resistor (wirewound)
    R8______________1K 1/2W Trimmer Cermet (optional)

    C1____________470nF 63V Polyester Capacitor
    C2,C5_________100µF 3V Tantalum bead Capacitors
    C3,C4_________470µF 25V Electrolytic Capacitors
    C6____________100nF 63V Polyester Capacitor

    D1___________1N4148 75V 150mA Diode

    IC1________TLE2141C Low noise, high voltage, high slew-rate Op-amp

    Q1____________BC182 50V 100mA NPN Transistor
    Q2____________BC212 50V 100mA PNP Transistor
    Q3___________TIP42A 60V 6A PNP Transistor
    Q4___________TIP41A 60V 6A NPN Transistor

    J1______________RCA audio input socket

    • Can be directly connected to CD players, tuners and tape recorders.
    • Do not exceed 23 + 23V supply.
    • Q3 and Q4 must be mounted on heatsink.
    • D1 must be in thermal contact with Q1.
    • Quiescent current (best measured with an Avo-meter in series with Q3 Emitter) is not critical.
    • Adjust R3 to read a current between 20 to 30 mA with no input signal.
    • To facilitate quiescent current setting add R8 (optional).
    • A correct grounding is very important to eliminate hum and ground loops. Connect to the same point the ground sides of J1, P1, C2, C3 & C4. Connect C6 to the output ground.
    • Then connect separately the input and output grounds to the power supply ground.



    A 15 watt amplifier made using discrete components. Sergio designed this circuit for his Electronics Level II course.


    This amplifier uses a dual 20 Volt power supply and delivers 15 watts RMS into an 8 ohm load. Q1 operates in common emitter, the input signal being passed to the bias chain consisting of Q8, Q9, D6, D13 and D14. Q8 and Q9 provide a constant current through the bias chain to minimize distortion, the output stage formed by a discrete darlington pair (Q2,Q4) and (Q7,Q11). The last two transistors are power Transitors, specifically the 2N3055 and MJ2955. The 7.02K resistor, R16 was made using a series combination of a 4.7K, 680 Ohms, and two 820 Ohms. The 1.1K resistor, R3 was made using a 100 Ohms and a 1K resistor. You can use this circuit with any walkman or CD player since it is designed to take a standard 500mv RMS signal.



    You can use this powerfull amplifier
    in any small audio project. It is very small (6.5 x 4.5 cm).It outputs 10W and uses a 9V battery.


    Componets List
    R1 : 6 Ohm
    R2 : 220 Ohm
    R3 : nothing
    R4 : 10 KOhm pontesiometer
    C1 : 2200 uF / 25V
    C2 : 470 uF / 16V
    C3 : 470 nF / 63V
    C4 : 100 nF
    C5 : nothing
    C6 : nothing
    IC1 : TDA 2003


    8 Watt Audio Amp electronic circuit diagram

    Here is the schematic for an 8 watt audio amp. This amp can be used as a simple booster, the heart of a more complicated amplifier or used as a guitar amp.



    C1 - 10uf Electrolytic Capacitor
    C2 - 470uf Electrolytic Capacitor
    C3 - 0.1uF Disc Capacitor
    C4 - 2000uf Electrolytic Capacitor 2200uF
    R1 - 2.2 Ohm Resistor Anything Within 10%
    R2 - 220 Ohm Resistor Anything Within 10%
    IC1 -LM383 8 Watt Amp IC ECG1232


    1. IC1 MUST be installed on a heat sink.
    2. C3 is for filtering and to prevent oscillation and should not be omitted.
    3. The circuit can be built on a perf board, universal solder board or PC board, the PC board is preferred. I built the circuit on a perf board and had to add extra inductors, capacitors and resistors to prevent oscillation.
    4. The circuit draws about 880 ma at 12 V.
    5. By swapping the values of R1 and R3, you can turn this amplifier into a guitar amp with no preamp required.
    6. If you can't find 2000uF, then replace C4 with a 2200uF unit.
    7. If you add a 0.2uF capaciitor in series with a 1 ohm resistor to the output you can prevent oscillation of the circuit under certain conditions.
  2. Mike33

    AAC Fanatic!

    Feb 4, 2005
    As a safety margin, most people run their speakers at 1/2 the amp's output power. So if you are rated at 8W, you could do 4. Now, I believe (and someone will comment, I'm sure!) that if you run the speakers in parallel they will share the load, and you could use the full 8W, perhaps leaving a margin of safety and say 6W.
    But for now, I'd assume a 4W amp. Then you can crank it and not worry.

    For home use, 4W is actually going to be pretty darn loud!!
    I would build the nice, simpl, final 8W amp you've listed and just be careful on how loud I turn it up (mostly, speakers will tell you they aren't happy with how much they are being driven before they blow, unless you crank it up suddenly!). You could add a series resistor to the volume pot to limit the amount you can turn it up, or modify the circuit's gain...
  3. Audioguru


    Dec 20, 2007
    Amplifiers and speakers are not operated at full blast all the time except for old acid rock noise. The power ratings for speakers is supposed to be the max continuous power at certain listed frequencies. But speaker manufacturers lie about power.

    An 8 watt power rating indicates a cheap or tiny speaker. Most half-decent speakers are rated at 60W or more.

    The "10W" amplifier with bass-boost on your list has an output power of only 0.8W into an 8 ohm speaker (1W into 6 ohms) for a couple of minutes with a brand new 9V battery that will be seriously overloaded.
  4. sarang2502

    Thread Starter New Member

    Mar 10, 2009
    The speakers are of Mercury 4.1 system with woofer. The amplifier circuit is crashed. Speakers are useless. Maybe i can make a 4 speaker system.
    When i opened speaker case, there is printed "H Y 6Ω 8W"...
    Please help.
  5. sarang2502

    Thread Starter New Member

    Mar 10, 2009
  6. sarang2502

    Thread Starter New Member

    Mar 10, 2009
    2X12 W HiFi Amplifier circuit


    Here is the circuit of a 2X12 watt HiFi amplifier circuit using IC TDA 2616 from Phillips.A quiet simple and robust circuit using very less components.This makes the circuit ideal for a portable power amplifier.The circuit delivers 12 W power on 8 Ohm speaker for each channel at +/- 12 V dual supply.

    The TDA2616 is a stereo power amplifier IC comes in a 9-lead single-in-line (SIL9)
    plastic power package (SOT131). This IC is specially designed for mains
    fed amplifier circuits, such as stereo radio,tape and television .The IC has good gain balance of both channels and Hi-fi in accordance with IEC 268 and DIN 45500 standards.Also the IC TDA 2616 has special inbuilt circuit for the suppression
    of noise signals at the inputs, during switch-on and switch-off.This prevents click sounds during power on and power off.

    Circuit Diagram with Parts List.


    All capacitors except C10 & C9 are ceramic.
    All capacitors must be rated 50V.
    Use a well regulated and filtered +/- 12 V dual power supply that is able to provide at least 2 A continuous current.

    TDA 2616 Pin assignment & layout.
  7. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    If u are unsure of what u are doing, then I suggest this site and learn everything written about audio amps.
    After that I am sure you will me more than satisfied.
    U can built a better sound system after that.


  8. Audioguru


    Dec 20, 2007
    This is what I posted on another website's forum two minutes ago:

    The Mercury company publish 3 different power ratings:

    1) The zipped file owner's manual says 30W RMS and that the woofer is only 4" and the satellites are 3".

    2) The first page of the sales sheet says 6 watts RMS per channel-Satellite and 24 Watts RMS Sub-woofer.

    It also says a rediculous 1980 watts PMPO.

    3) The specifications page says Sub-woofer: 15 Watts and Satellites: 9W each.

    The Philips (NXP Semi) TDA2616 amplifier IC is not made anymore and has been withdrawn.

    Its datasheet shows that its output was 6W per channel at clipping into 8 ohms with a plus and minus 12V supply. Its output was 10W per channel into 4 ohms. It might give 6W into each of your little 3" speakers when two speakers are in parallel for each channel.
  9. sarang2502

    Thread Starter New Member

    Mar 10, 2009
    Sir, i searched for the IC in markets and found that it is available here.
    Please suggest that should I go ahead with this circuit?
    I found it to be best suited.
    In Parallel, I can use all four speakers.

    But it has output of 12W on 8ohm load. So, will my 6ohm (3") speakers work properly in parallel connection? If any changes in circuit should be made then please suggest me.

    Also I want to know that will the circuit require more than 2Amps current?

    Thanks a lot!

    Last edited: Jan 5, 2010
  10. Audioguru


    Dec 20, 2007
    Why not use a stereo amplifier IC that is still being manufactured? Then it can be replaced if it fails or you can make more amplifiers.

    Only if its power supply is plus and minus 16V.

    The datasheet shows 10W into 4 ohms with a plus and minus 12V supply. Then the output is probably 12W into 3 ohms so each little speaker will have 6W.

    The datasheet does not have details like most other amplifier ICs have on their datasheets. Since its output will be 12W and it will heat with another 12W then its total power is 24W. Its max continuous current will be 1A at plus 12V and 1A at minus 12V.
  11. mahwish qazi

    New Member

    Apr 26, 2010
    i need an power audio multistage amplifier circuit of 5 watt not using amplifier IC but discrete elements for our projct urjently till 2morrow..:( :'(
  12. Audioguru


    Dec 20, 2007
    I think your teacher wants you to design a simple 5W audio amplifier.
    There are thousands of 5W amplifier circuits on the internet but your teacher will search and find the one that you simply copy.
    little katty likes this.
  13. little katty

    New Member

    Apr 26, 2010
    mahwish here
    we have searched many frm the net nd all r rejected by our teacher..
    v have 2 submit the project on hardware 2morrow nd even dun have a circuit yet..:(
  14. Audioguru


    Dec 20, 2007
    Your Engrish is horrible.
    If you are studying how to simply copy designs by others then here is a discrete 2W amplifier that gives 5W when its supply voltage is increased:
    little katty likes this.
  15. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    OP's teacher is in this forum just in case you didn't know. :D
  16. Audioguru


    Dec 20, 2007
    Frequently when a school kid wants us to do his homework for him his teacher logs in and tells him NO!
  17. little katty

    New Member

    Apr 26, 2010
    thanx alotttttttttttttttttt:) guru ...
    well whz that teacher????????????:rolleyes: