Low Cost 150 Watt Amplifier Circuit

In this project, we’re building a simple 150 watt amplifier circuit.


This is the cheapest 150 Watt amplifier circuit you can make,I think.Based on two Darlington power transistors TIP 142 and TIP 147 ,this circuit can deliver a blasting 150 W Rms to a 4 Ohm speaker.Enough for you to get rocked?;then try out this.

TIP 147 and 142 are complementary Darlington pair transistors which can handle 5 A current and 100V ,famous for their ruggedness. Here two BC 558 transistors Q5 and Q4 are wired as pre amplifier and TIP 142 ,TIP 147 together with TIP41  (Q1,Q2,Q3) is used for driving the speaker.This circuit is designed so rugged that this can be assembled even on a perf board or even by pin to pin soldering.The circuit can be powered from a +/-45V, 5A  dual power supply.You must try this circuit.Its working great!

The preamplifier section of this circuit is based around Q4 and Q5 which forms a differential amplifier. The use of a differential amplifier in the input stage reduces noise and also provides a means for applying negative feedback. Thus overall performance of the amplifier is improved. Input signal is applied to the base of Q5 through the DC decoupling capacitor C2. Feedback voltage is applied to the base of Q4 from the junction of 0.33 ohm resistors through the 22K resistor. A complementary Class AB push-pull stage is built around the transistors Q1 and Q2 for driving the loud speaker. Diodes D1 and D2 biases the complementary pair and ensures Class AB operation. Transistor Q3 drives the push-pull pair and its base is directly coupled to the collector of Q5.

Circuit Diagram & Parts List .

150 watt amplifier
150 watt amplifier circuit diagram

PCB’s for this project can be ordered through PCBWay. We shall upload a sample PCB file (for download) shortly.


  • Remember TIP 142 and 147 are Darlington pairs  .They are shown as conventional transistors in figure for ease.So don’t get confused.Even though each of them have 2 transistors ,2 resistors and 1 diode inside ,only three pins ,base emitter and collector are coming out.Rest are connected internally.So its quite OK to assume each of them as transistor for ease.
  • Use a well regulated and filtered power supply.
  • Connect a 10K POT in series with the input as volume control if you need.Not shown in circuit diagram.
  • All electrolytic capacitors must be rated at least 50volts.

Power supply for this circuit.

A  +40/-40 unregulated dual supply for powering this amplifier project is shown below.  This power supply is only enough for powering one channel and for stereo applications double the current ratings of  the transformer, diodes and fuses.

amp supply
Power supply for this project

TIP 142 & 147 Internal diagram and pin out.

TIP 142-TIP 147 Pin Out Diagram and Schematics
TIP 142-TIP 147 Pin Out Diagram with Schematics

Note:- We have explained how to create a schematic of this circuit and its PCB using an online EDA tool – EasyEDA.  You may read the article to understand how to draw and develop a PCB of this circuit.

We have more related list of  Amplifier Circuits that you may like to visit;

1. 2 X 60 Watts Stereo Amplifier Circuitis designed using LM4780, an audio amplifier IC that can deliver 60 Watt RMS output power per channel to  8 Ohms speakers.  Advantages of using this IC are low harmonic distortion compared to other IC amplifiers of similar category and a power supply rejection rate of 85db. In addition it require minimum components and a built in mute function.

2. Headphone Amplifier CircuitThis is a simple circuit which uses only 3 transistors, that can be used to drive your headphone. It can be easily built by any one and can be powered using a 3 volts battery.

3. Mosfet Amplifier Circuit This circuit is designed using two Mosfet’s and one transistor; which makes it an easy to build circuit. It can deliver 18 Watts output power to 8 ohms speaker or 30 watts to 4 ohms speaker; you can do it the way you like it. Another advantage of this circuit is the minimal use of components.

4. 40 Watts Amplifier using TDA1514 TDA1514 is a high performance hi – fi amplifier from Philips. It requires a dual +25/-25 volts supply. Advantages of using TDA1514 are low THD, mute standby feature, thermal protection and other features. It can deliver 40 watts of output power to an 8 ohm speaker. You need a proper heat sink for the desired reliability of this circuit.

5. 2 X 32 Watts Stereo Amplifier CircuitThis circuit is built using TDA2050 which is a 32 Watts Class AB Audio amplifier IC (monolithic) . This IC has many features like thermal shut down, low THD, short circuit protection etc. This circuit uses Two of these IC TDA205o; one for each channel.  An 18 volts dual power supply is required to power this circuit.



  1. Seetaraman thanks for explaining technically but I’m not that technical 🙁 What should I do with my MM to test it? Should I put current measuring on Tip142 base to collector?

  2. seetharaman

    Hi Andy for a class B amplifier with signal only they should conduct otherwise it should not draw any current theoretically. One output transistor will conduct for 180deg of the input signal and the other balance 180deg. But due to mismatch between the transistors it is not practicable. This will give raise the transfer of conduction from one transistor to other one, may for a small angle both may not conduct. This will start giving crossover distortion.(high volume level will sound ok but very low volume signal will be highly distorted. To avoid this a small forward bias is given to the output transistors (without signal say 50 to 100ma, such that they conduct little over 180deg so there is a overlap between their conduction). This current is called standing current. This is normally measured in the collector circuit of the output transistor without any input signal.

  3. required from any one good amplifier circuit + its PCb

  4. Seetharam what did you mean collector current without any input signal. Can you please clarify?
    I am hearing alot of distortion from my circuit 🙁

  5. seetharaman

    Hi Verma guaranteed RMS output is >100 watts with 8 ohms speaker and >150watts with 4 ohms load. it is recommended to use 8 ohms speaker as there is no protection circuits used, only simple fuse protection against short circuit of the output is provided.

  6. Wat must be d impedance . . .8 or 4 in ckt it is givn 8 n in description 4. . . . .

  7. Tanx ,n wher can i learn d basics of audio amp

  8. seetharaman

    Hi Varma 10″ or 12″ with free cone movement, not a rigid one.
    Hi Andy TIP142 collector current without any input signal.

  9. N can u plz giv me a link wher i can learn basics abt audio amplifiers . . .

  10. Tanx again for ur response ,which kind n size of driver is better for subwoofer using d above 150w ckt. . .

  11. Hi Seetharaman thanks again. Sorry regarding my little tech knowledge but I need spoon feeding :). When you said check standing current through output transistors, it should be around 50 to 100mA. Which are the output transistors those TIP ones? and I check collector to emitter? Which one you’re refering the output transistor?

  12. And, Can u plz send me a subwoofer ckt using tda1562q . . . .plz do reply

  13. Well tanx a lot seetharaman for ur response ,can u plz giv me d links of subwoofer filter appropriate for dis ckt . . .

  14. Well tanx a lot for ur response ,can u plz giv me d links of subwoofer filter appropriate for dis ckt . . .

  15. seetharaman

    Hi Andy you may feed a quality music from your ipod, through a volume control of 22K or 47K to the amplifier and listen. If the quality is good then amp is ok. if not check standing current through output transistors, it should be around 50 to 100mA. if not check the output transistor wiring. check the circuit thoroughly for errors correct them. it is a proven circuit with the transistors recommended.

  16. thank u SEETHARAMAN for ur imediate response. it has worked for me. am fine now

  17. Hi Seetharaman thanks for response. Is there a way that I can check it without preamp? cause a hi gain of distortion is coming from the speaker. I tried a one transistor pre amp but still nothing came out with mic maybe need a more powerful pre amp?

  18. seetharaman

    Hi Mos connect 10 ohms 25 watts as dummy load in place of speaker and check the voltage across this resistance, it should be just a few milli-volt. if it is high check for mistakes in the component / wiring.

    Hi Andy the input requirement for the rated output is 200mV RMS Mic signal will be around 1 to 3 mV. Hence you require a pre-amplifier gain of around 70 to 200.

  19. I read on this forum that one needs a pre-amp to this amplifier for mic maybe this is my problem I will build a small pre amp and see.

  20. hi admin.mos from nairobi and am pleased with ur circuit. its awesome, except for one problem i experience at startup of the amplifier where i hear a thud noise from the speaker . what should i do coz the voltage there is 35v dc. plz assist before my speakers blow off. thank u in advance

  21. seetharaman

    Hi Varma use this amplifier after the sub-woofer filter. From your DVD player feed the sub woofer output directly to this amplifier using a potentiometer to balance the Low Bass level.

  22. can anyone plz tell me how 2 use dis ckt for a subwoofer

  23. Today I’ve changed the transistors. Only loud distortion is coming out nothing from mic 🙁

  24. I think I am using wrong transistors. The guy of the electronic store told me that BD243c;BD241 and BD244c are good instead those Tip transistors but when I saw their datasheet they are not darlington :(. So I have to go and get the right equivalents if I don’t find them.

  25. I was very enthusiaistic about the amp, after reading comments. i took time and did things diligently, i did everything from scratch including making my own PCB
    getting transformer made from custom shop,I built the amp, but I was totally dissapointed with the experiments result,

    I used 50-0-50v 5amp
    when i measure the voltage was around 58-60v
    Audio input is around 12-20mv
    i used 1.5E 6w instead of .33E 7w which turned to red hot the moment i turned the power on
    later i changed the resistor to .5E 10w same thing it turned red hot with internal wires visible.
    i had to switch it off before it is burnt.

    Can any one help me troubleshoot the amp.

  26. Mordis Ellis

    Here i have an HWCAT IC CSC2003P,Is there any simple circuit you can suggest for me?

  27. Mordis Ellis

    Seetheran,i have here an IC2822,Which circuit can i design using it?give full details pliz.again on dealing with a 150w amplifier i can’t find the nf capacitors.and my havit HV-A35 amplifier ic is burnt so i cant find LM4863D IC which one can i replace with?please help.

  28. Olasubomi Idowu

    I was actually looking for a 600watts amplifier design from the foundation to the finishing of the project.

  29. Yes for sure I did that but I did this circuit on a bread board to test and I’m thinking that certain components not contacting well.

  30. Seetharaman

    Hi Andy you require both plus and minus supply. with + & – 12 volt you will get distorted low sound.

  31. Hi Seetharaman thanks for response. I cannot make this circuit work with 12v supply don’t know why 🙁 . I am using 243C 241 and 244c instead of the Tip142/41/147 transistors.
    I connected a mic to try to hear something but nothing till now.
    Still testing.

  32. Seetharaman

    Hi Hengilbert Thanks for your observations. your ideas are correct but these components need not be mounted on the heat sink, the circuit will get over compensated, hence it can be just nearby. The presets are always a problem for the constructors, with least tools hence it is always preferred to eliminate these complexities to enable them to have successful results without any disappointment, in the first attempt itself.

  33. Hengilbert

    Hi Seetharaman,

    you can mount the tip41c to the heatsink alongside with tip142 and 147.Adjust it first to minimum and slowly adjust.
    or with the original circuit,you must put the diodes near the heatsink to sense the heat.

  34. Mordis Ellis

    I have again the two IC’s (CSC2822 and CSC2003P)so i’m wondering which circuit can i construct with those two?

  35. Mordis Ellis

    Hi!i have a havit HV-A35 Speake with built in amplifire with an ic LM4863D which is damaged and so i can’t find it in stores,which one else can i use to replace the LM4863D?PLEASE GIVE ALL SUITABLE IC’s.

  36. Mordis Ellis

    Which transistors can i use except the stated ones?i’m in Lesotho.

  37. Seetharaman

    Hi Hingilbert it is ok but the preset adjustment will be critical and over a period of time they give problem and out put current will raise damaging out put transistors, the modification of the above site also will give thermal compensation as above but for the indicated preset problems.

  38. Seetharaman

    Hi Mordis all capacitors are rated for 50volts. if you can give us what is available in your place we can suggest you which one you can use as equivallent

  39. Mordis Ellis

    Hi! I want to deal with a 150 watt amplifier but the problem is that the voltages of the capacitors are not stated and i cn’t fint some of the transistors in my place,coul anyone please help with the voltages?i’l b more than happy if i can get them.

  40. Seetharaman

    Hi Andy this amp will give some highly distorted sound. with plus and minus 12 volt from the 12 volt transformer. nothing will blow.

  41. Hi I am trying to work this ciruit with a 12v transformer to a 2w speaker. Do I blow them both?

  42. Seetharaman

    Hi Mike of course you can substitute a 10+10 stereo amplifier. you can place it in between the pre-amp out and 10 watt stereo amplifier.

  43. ….so purely op-amp and no other elements needed??

  44. hi there, is it ok instead of two amplifiers(10w rms) i will substitute a stereo aplifier at the same wattage??

    …and where do i place this circuit?..is it ok to place it after my preamp? (my preamp is also an op-amp)….

  45. Seetharaman

    Hi Mike you can use two operational amplifiers in one, connect Left channel signal to non inverting input and Right channel signal to inverting input the out signal will be left – right signal feed it to an amplifier of around 10 watt RMS and place speaker at the rear left. Carry out vice-versa you will get R-L signal; feed it to another 10watt amplifier and place the speaker at rear right. with mono signal your sound image will appear at the front center other speakers will be dead. with stereo signal you will get the surround effect.

  46. Hi there, do you have some additional circuit use to generate multichannel and incorporate it with existing two channel(Right and Left)???

    other suggestions?………

  47. Seetharaman

    Hi Dieudonne you have to use PNP and NPN power transistors with zener diodes etc please refer to active series pass regulators.

  48. Dieudonne

    And can i use 2x100ohms 1watt on either power (+/-) as a pass regulator?

  49. Seetharaman

    Hi Dieudonne it is not possible in this application as the load current is not constant and varying one as per the volume level kept at the amplifier (power delivered), hence you have to use series pass regulators for both positive and negative supply.

  50. Dieudonne

    Hi i want to regulate the power of my transformer from 45v to 35v by using a POT. Which resistant should i use.

  51. Seetharaman

    Hi Mark012 connect a 4.7k in series with the slider of the control to input of the amplifier. add 470 PF in parallel to R7. Now connect 0 volt reference bus to chassis at the input socket. (earthing to chassis from 0 volt bus should be done at one place only multiple grounding will give raise to severe hum).

  52. Hi, I want to ask the same, about connection PCB ground and chassis earth. Do I have to wire direct link or put some resistor or diode?

  53. Hi there. At the end of my preamp there’s a 47k pot. Should I put some component between pot an input of amplifier or not? Does it change input gain of power amp? And what about conection of a PCB ground and chassis?

  54. Seetharaman

    Hi Mic inter change the speaker terminal and try the feed back phase will change still no effect reduce main amplifier coupling capacitor to lower value may be 2200pf or so. most scientific method will be introduce a graphic equalizer bet ween pre amp and main amp and reduce level of each pot at a time and one pot or two should solve your problem.

  55. hi there, my next problem is the noise feedback created when i put my microphone near to the loudspeaker….

    do you have some circuit design or suggestions to eliminate this feedback?…

  56. hi,….ok so no need to replace my output transformer…thanks for helping,,,….

    ok, I will try it…

  57. Seetharaman

    Hi Mic your filter capacitor should be at-least 10000uF. your amplifier ground and booster amplifier ground should be connected at only one place. ensure no hum is introduced from the main amplifier. you may have to give a overall feed back to first amplifier from booster amplifier out put to linearize the amplifier. with this your amp should work fine.

  58. Hi there, I’ve change the biasing resistors and have a current of 29mA and the music is good but i am not satisfied because there is a humming noise……is it because of the power supply? or still there is another problem?,…my power supply by the way is not regulated only filters….

    or should i increase the power of my output transformer to greater value because i have only 50watts?….pls…help me…

  59. hi, can you email it to me your schematic diagram of transformer coupled booster?

    actually I made an experiment, from 470 ohms i reduce it to 300 ohms, and i find out that the music is ok, but i notice when i decrease the volume i heard humming noise…

    i will wait your design, thanks….

  60. Seetharaman

    Hi Mike without input to your coupling transformer check the current drawn by the out put stage (2 X MJ2955)if it is around 25 to 50mA, it is ok if less increase 12 ohms to 15 etc. If high reduce to 10 etc. Once you are satisfied now feed the input to coupling transformer through a 1K pot. Now check whether the distortion is reducing. now vary the drive to coupling transformer and listen.

  61. My power supply is 12V,6A. I’m using transistors value of MJ2955…..

    so, what should I do with my coupling transformer?….

  62. Seetharaman

    Hi Mike Your 25 watt amplifier will saturate the driver transformer cores. this will lead to severe distortion. your bias resistances are OK but you have not mentioned the supply voltage to your push-pull add on circuit and about the PNP transistors whether they are germanium or silicon to give further comments.

  63. hi there, i build a transformer coupled push-pull amplifier using PNP transistors. My plan is to boost my 25W amplifier. But then, i come up with distortion, both input and output transformer are center tap and biasing resistors R1=12ohm, R2= 470ohm….can you help me solve my problem……

    and pls. email it at micburn18@yahoo.com.. thanks…

  64. Seetharaman

    Hi Dieudonne you can use up to a maximum of 35-0-35 volts transformer for this circuit.

  65. Hi Mr.Seetharaman, I have compiled amplifier by all the instructions (change R8 and R9 to 10watt, put a 470p cap on colector-base on both darlingtons, have a zobel network – 0.1uF with 10R 1watt, change C1 to 100uF, crossover distortion diodes are 1x 1N4007 in series with 2x 1N4003 and 12ohm resistor, have a 40-0-40 DC 270mV transformer, use 2x 8 ohm celestions speakers) but when turn ON the amp, there is a huge low noise and sound isn’t clean, there’s a still some distortion. What now? I got a good RMS power but and lot of noise too….??? Do you suggesting to continue with this amp and find a solution or made another for myself??? Im a musician and want something fine “selfmade amp” for myself.

  66. Dieudonne Dorwu

    can i use 50k pot/100k pot instead of 10k pot.Because i only got 50k and 100k pots.

  67. Adil Shamim

    hi i build this circuit when i power on my speaker blow (4 ohms 80 watts) i used 45 0 45 power supply .any one solve this problem

  68. Seetharaman

    Hi Mark012 it looks like your speaker impedance is low hence with high volumes the peak out put current exceeds the safe limit of out put transistors. You can increase emitter resistance to 0.47 ohms 10 watts. You kindly refer to my motional feed back amplifier the protective diodes in parallel to output transistors and the Zobel network also can be included as additional protection.

  69. I need answer! If anyone knows a solution???

  70. Mr. Seetharaman, problem solved about output, it was my mistake about R7. But…I have another problem now. Everything works great until push up volume to about 8/10. Darlington transistor blows up at that volume! What now? I have a large heatsink from older amplifier and think that’s not a problem.
    Should I change R8 and R9 to 7-10 watts or what?
    Thanks for responding….

  71. hai

    this circuit is perfect, but if the load is 8ohm 8″speaker with tweeter and use la 3161 head pre + baxandall tone circuit system need for hearing quality



  72. Dieudonne Dorwu

    I used 5w0.33 and when i aplified it, the transistors went off. Because i couldn’t the 7watts. And i ask can i use 10watts.

  73. Seetharaman

    Hi Mark012 these are perfectly OK. Try by i ncreasing C1 from 10uF to 47uF. already the amplifier gain is around 100, hence i feel your input level is insufficient drive the amplifier.

  74. Hi again Seetharaman, I still have a problem with not enough output power!?! On my PCB I use 2x bc556 instead of bc558/ R8 and R9 are 2x 0.33 5W resistors/ diodes are 1x 1N4007 + 2x 4003 in series with 12ohm resistor. Everything else is like this original circuit.
    Is this componets are problem or something else???
    Thanks for helping and responding…

  75. thank you a lot for the circuit. i have finally made it but with omission of R1 and R7. for me its working better than having the two resistors in place. from Nairobi Kenya

  76. i tried it but wont work at all. do not know what to do

  77. Seetharaman

    Hi Mark012 with 42-0-42 DC supply you should get more than 160 watts. May be your input drive is not sufficient. You require 300mV RMS input signal for the rated out put. Just try connecting 100uF 25 volt in parallel with 33 ohms (R10) the sound should become bold. You can try with 45 0 45 volt 6Amps power supply. As with lower impedance speakers you require a higher peak current capability from the power supply.

  78. Mr.SEETHARAMAN, I try this circuit amp with good hi-gain guitar preamp and I got a about 60-70W RMS at 4ohm (2 speakers parallel at 8 ohm 100W each)!?! I compare my amp with a guitar amp “Marshall AVT 50 (50W power)” at the maximum power and looks like almost the same output power. So what’s a point to get a 100-150W RMS with this amp schematic.
    TIP 142 and 147 works at 100V and can handle 125W maximum. I use 42-0 -42 volts at 4A.
    Sory if I’m boring you but I need at least a 100W RMS power for live gigs playing…
    Is this circuit realy give a 150W RMS power or I did something wrong???
    Thanks for understanding….

  79. Seetharaman

    Hi Richard Tip142/147 are Darlington pair with a current gain of around 1000 but C5198 is just a transistor with a gain of just around 60,hence cannot be used.

  80. @kambo
    I’ve used 1/2W resistors. Not much current gets through them so i believe 1/4W could be used too

  81. Very good project and extremely efficient for driving subwoofers. Just add a potensiometer between input and source and let there be music!

    Just install efficient heat spreaders on tip/bdw, they get HOT!


  82. What is power (watts) of the rest of resistors used on this 150w amp.

  83. plz help equivarent of ceramic capacitor 103 and 2k470j how do i convert them to uf.

  84. Hi circuitstoday, i would like to ask favor from you can you send me please PCB layout of 100watts subwoofer, 150watts & low pass filter. just send it to my email ad. thank you very much for youre help.

  85. Hi, this amplifier looks promising… I want to use it on a 4Ohm subwoofer, a 25-0-25 ac transformer 6Amp should be appropriate, right?

    Seetharaman could i have a project description sent in my email? Thanks in advance xhorium@hotmail.com

  86. hey……
    i’m myanmar.
    220volt amplifier circuit diargram see.

  87. Seetharaman

    Hi Marko12 you can use this amp with suitable guitar preamp. you can fix this also in side a good solid speaker enclosure

  88. I want to try to build this amp but can I use it as a guitar amp? How good is this amp for a guitar and a guitar cabinets

  89. 24-0-24v, 5A. Power supply for 150w amp will it be okey?

  90. Seetharaman

    Hi Sebin you can do that. it will be a nice sub woofer amplifier. Kindly add a 330PF ceramic disc capacitor between Q3 collector and base.

  91. is it possible o connect a bass filter before the input and use it as a sub woofer amplifier

  92. BIju Ghosh (India,WB,Howrah,santagachi)

    no comments it work fine….i built this one,very good circute

  93. gud day, seetharaman,. nice IC. can i use 12 amperes as a power supply to tda2030? LM4702 is not available here in our place..

  94. Seetharaman

    Hi Rogelio LM4702 (a power amplifier driver IC)will give an output of more than 60volt drive for the output transistors which as per their application data 300 watts RMS power with least distortion. you can use +100 & -100 volt supply to get 7 volt RMS with quite low distortion of less than 0.001% . Anice IC to try if available freely i the market.
    you may go through national datasheet


  95. hi, seetharaman. tnx 4 the reply last feb 23,. uh, can i ask u what is the output power of LM4702b?

  96. ,seetharaman..tnx 4 d rply.. I thought u will send me the project capability and limitati0ns to my email..? U said dat in ur c0mment ryt? C0z u said, the space here is n0t sufficient.. I didn’t receive an email fr0m u..

  97. Seetharaman

    Hi Tel refer my earlier comment
    Hi Laeka to enjoy high fidelity music you require a good soft thumping low frequency reproduction. this can be achieved through a good quality medium to high power amplifier. it is not that you will be blasting always at 150watts but with modern digital equipments capable of producing 90dB dynamic range you can enjoy the music without any distortion creeping in. This circuit is a simple straight forward good design, that is an added advantage.

  98. Seetharaman

    Hi Tel the project limitation is 150 watts into 8 ohms speaker. this limitation is due to the thermal resistance of the output Darlington pair transistors. send me your email id i will give you full description. here the space may not be sufficient.

  99. ,and also can u give me the project description of this circuit? Tenk u..

  100. ,seetharaman..tnx 4 d rply, i hav an0der questi0n. What is the pr0ject capability of this circuit and its limitati0ns? Pls rply..tenk u s0 much.

  101. Seetharaman

    Hi Tel +44 – 0 -44 volt 2Amp supply will be just right. If you are assembling stereo amp with this use RCA-Phono sockets for the input. (most rugged and fail safe)
    Hi Laeka to enjoy high fidelity music you require a good soft thumping low frequency reproduction. this can be achieved through a good quality medium to high power amplifier. it is not that you will be blasting always at 150watts but with modern digital equipments capable of producing 90dB dynamic range you can enjoy the music without any distortion creeping in.

  102. what is the general objective of this project pls reply thanks

  103. seetharaman can you please give me the complete computation of this circuit? i need it so badly, our submission of this project is fast approaching…plssss.. and what kind of babay jack am i going to use? mono or stereo?

  104. seetharaman i need ur reply,, is my power supply right? it has 44 for positive and 44 for negative?

  105. Seetharaman

    Hi Rogelio wattage is V (AC voltage available across speaker terminals with load)square divided by impedance of the speaker. hence you will get half the out put for 8 ohms instead of 4 ohms. that is 50watts.

  106. gud day,! thanks a lot seetharaman,. uh, wat will be the power output on 8 ohms?

  107. Seetharaman

    Hi Rogelio +/- 30 volt can be used. the power output to 4 ohms speaker will be around 100Watts. you require only a 2amp supply for stereo 4amps that is all the requiremen, which TIP142/147 pair can handle.

  108. hi seetharaman, can i use a +/-30 15amp to the tip147 & tip142.?

  109. This amplifier is amazing, i have build the amplifier several times, but the Amplifier is too complicated, at times when i assemble it in Mono, it works well, but when i do it in Stereo, i have problems, then the transistors are very sensitive and quick to be blown, that is my problems, but i usually run the amplifier with a +/- 35v instead of +/-45, why do i keep having this problems?? please any help forwarded to me at dnkwenti@gmail.com will be appreciated, my greetings to you all.
    ……………….PEACE AND GOOD LUCK………………..

  110. Seetharaman

    Hi Crystel you can use 2nos capacitors in series with parallel distributing resistances, can be 2.2K 0.5watts.

  111. ,can someone tell me wat capacitor can i replace in the p0wer supply of this amplifier. The 63v is n0t available here in manila.. Only 50v I need a reply.. Plss…

  112. itsme_chad

    does know the alternate transistor for bd708

  113. hi sir seetharaman im done with the circuit tnx…
    i have a question i have amplifier konzert av 301 with
    22 0 22 volts and A1941/C5198 transistor.. if i make the transformer 35 0 35 does make the amplifier add its watts? this will not damage the amplifier? tnx

  114. tnx seetharaman.. am drilling the pcb.. i hope it works… tnx

  115. Seetharaman

    Hi Richard you can use TIP41C in the place of TIP41.
    TIP41 Vceo 40 Volt
    TIP41A 60 Volt
    TIP41B 80 Volt
    TIP41C 100 Volt
    But for the above parameter there is no other difference between them.

  116. sorry its not bc558 its tip41c.. can i use that? tnx

  117. Hi admin there is no bc558 available.. bc558c is only available here can i use that transistor? tnx

  118. HI seetharaman

    i am very happy to meet you in this site after long time

    what about 500w pa amp still construction is going on?

    i am very eager to do that amp

    thank you

  119. please give a practical transistor combination for the npn and pnp darlington transistors.eg,tip147 is (tip41+d718+in4007).

  120. Stephen Payne

    As for a mic input, you would need a pre-amp to get enough gain.

  121. Stephen Payne

    As stated in this article, you need a good quality power supply. In my experience you need power supply decoupling caps very close to the amp circuit. In addition a cap(10-100pf) from C to B on the TIP41 helps a lot. Also, you can add a 100pf(approx) from input to common. It is fairly easy to scab in these caps on the bottom of your board.

    As posted earlier in this thread, addition of an RC network on the output adds stability.

    I am working on a layout that incorporates these suggestions. I will post when it is ready.

  122. hi all i hv tyied above circuit with 1)R8 & R9=10watt.33ohm 2)R3 &R5=33k(33000ohm) 3) power supply =35-0-35 4)audio in =mic 5) pcb lay out stephen’s
    my prob is when i give it voltage input tip142 & 147 get warmer plzzzzz anybody who has tried it tel me what is the basic or main problem in it
    response me soon plzzzzzzzz

  123. using mic this circuit is not working:( pcb lay out used is Stephen’s design…..

  124. hi Seetharaman i have try this circuit as my project with 35-0-35 i/p supply, 8ohm 100watt, but i need to knw about i/p if i use a mic will it work? or what can i do to input audio?

  125. hello, for those people making this amp there first project make sure not to use imitation output transistors, especially residing in Philippines!marami kasing fake!

  126. wat will happen if the output terminal and the input terminal for power supply is near from each other???
    hum noise???

  127. Hi seetharaman did you remember me what about 500w pa amp

  128. i am happy to know that this circuit is funtioning well. but i want to ask if we can use a supply of 30 0 -30v. i also wish to request for the 1500w inverter circuit. i am waiting pleaseeeeeeeeeeeeeeeeeee.

  129. shailendra007

    hi, i was made this project on general p.c.b but it was not working , what was reason i dont know ,please help me

  130. Seetharaman

    Hi Caloy 3 diodes are just sufficient to operate on Class B mode.
    Hi Basha you can turn a thyristor on with the positive gate pulse but cannot control with gate pulse there after. You have to reduce the current flow through thyrister below its holding current to switch off.

  131. Is there any thyristor which turns on negative gate voltage and turns off on positive gate voltage.

  132. Stephen Payne

    I got good results with 3.3K resistors in place of the 33K resistors.

  133. how many bias diodes do you require which will work the best???

  134. Seetharaman

    Hi Edcube the quality can be improved by adding one more diode and a 10 to 22ohms resistance in series with the existing 2 bias diodes D1 and D2. Ensure the no signal currnet through the output transistors are within 50mA.

  135. I built this amp. It works but the crossover distortion is quite bad especially at low power levels. It can be seen very clearly on an oscilloscope. It seems the comment previously posted by somebody is true. (That comment is gone though – removed?.) This amp is OK as long as you are not looking for high quality sound.

  136. thanks for that info mr.seetharaman…32-0-32 is not available here…

  137. seetharaman

    Hi Caloy you can use 24-0-24 which will produce dc 34-0-34. with 3amps current capability will ensure 125watts into 4 ohms speaker. with 8 ohms speaker 62watts will be delivered.

  138. is it ok if i use 24-0-24 transformer for this project????

  139. Seetharaman

    Hi DAN46 TIP147 is a PNP Darlington pair. you can try using BD140 with TIP2955 in Darlington with 1N5404 / BA148 diode as indicated in the above pin out details.

  140. Plsssss!!! I ned d cal for dis amp.as much i can get.i ned it 4my writup.cal 4rm d power suply,stages cal and power consmp&los.u can email me.thaankss in advanc
    my email is boyolu4real@yahoo.com.i’m watin badly

  141. HI pls how can i get the tip147 transistor?? or can i use tip3055 for tip147?

  142. is it ok if i use .47 ohm 15watt resistors for R8 & R9???

  143. Seetharaman

    The one off test model is under rigorous tests.

  144. Pls i ned diag4 d +/-45v dualpower suply witout IC

  145. Pls can i build +/-45vdual power suply witout using IC?i ned hlp on d circt diag

  146. mr.seetharaman


  148. Seetharaman

    Hi Segzy you have to use both positive and negative supply. with one supply only it will not work.

  149. Is it comp 2use dual pwer suply 4d amp?can i use+45v btwn d +ve tminal&GND 4d amp?can i also 12-0-12 voltage doubler 2obtain 48v 4d amp

  150. thank you very much. I found the collector emitter short and hope it was due to the heat sink (as I forgot to fix them on first power on). I will do the rest of the modification and let u know the results.

  151. Seetharaman

    Hi Saju checkup for transistor collector emitter short (though base emitter and base collector is ok). check the polarity of bias diodes. R5 = R3 = 3.3K (3K3). have you fixed HF stability components. 1k with 470PF at the input. 100PF between collector and base of Q3. fix 0.1 uF ceramic disc in positive and negative power supply rails. with this it should work. all the best

  152. hi caloy
    The PCB been adopted from the diagram on the web.

  153. I am using +/- 35V with 5Amp fuse. And also have the PCB which is available on net. I have gone through your earlier comments and doubts whether the fuse is blowing because of the HF instability?. The very first time when I swiched the Amp on it amplified the signal. There after no respose to the input also!!!!!!?
    All the componets are in good condition
    kindly advice me what to do.

  154. hi, Seetharaman
    I have tried the circuit but the fuses on both + and – power supply keeps blowing. I have done the visual inspection could not find any wrong connection. please advice me

  155. Seetharaman

    Hi Adnan you can use 0.47ohms 5watts resistance for each transistor, so that each transistor is taken care from over current(equal distribution of current will take place) all will share the current equally.
    Hi Saju a simple fast acting fuse can protect the speaker from burnout.
    Hi Caloy only 900mA will be consumed the balance is the additonal capability of the power supply, that will be in reserve. nothing will happen to the components. if you have a 40 watt bulb connect to your domestic mains which is capable of 5KW before blowing the fuse, the 40 watt bulb will consum only 40 watts not more than that.

  156. is there a possibility that the device will be destroyed???

  157. what will happen if i use a 2 amp power supply on a device that requires only a 900mA of current???

  158. can you provide speaker protection circuits for the amp


  160. Seetharaman

    Hi Adnan proper way of paralleling with emitter split resistance it can double the power with lower impedance speaker. with 45-0-45 and 4 ohms speaker you can achieve 300 watts,

  161. if we use 2xTIP147,2xTIP142,TIP41 in parallel @ 45-0-45v 4A
    will the output of amplifier increase from 150watts?

  162. Seetharaman

    Hi Saju you can use down to + – 25 volts. Note the resistances R3 and R5 are 3.3K ohms.
    Hi Jack The amplifier gain is set at 100. (R4 / R2)
    With 45 volt supply and with 8 ohms speaker to achieve 42 volt pk to pk ( 42 / rt2 = 30 volt RMS i.e 30 X 30 / 8 = 112.5 watts RMS) you require 42V pk pk / 100 = 0.42V pk to pk.
    For clues in construction please go through my comments from the beginning.

  163. hi, Seetharaman
    Can we use +/- 35V supply for this circuit.

  164. Jack Daniel

    Hi, Seetharaman, I’m Jack Daniel
    this amp is look simple to build, can you please explain what is the full specification such as
    min & max of DC Voltage for this circuit.
    Secondly what is the input signal voltage peak to peak, so we don’t overload the poweramp circuit which can create unwanted distorted sound.

  165. Seetharaman

    Hi Adnan it should be 10-0-10 volt 25 Amp capacity (6-0-6 shown is incorrect) transformer will be best suited as you have to take care of saturation voltage of transistors. collector to collector shorted indicates that they are all on the same heat sink without insulation. otherwise the circuit is in order

  166. Seetharaman

    please refer to my earlier comment:
    seetharaman says: June 25, 2010 at 9:18 am Hi Bryce You can connect the volume contron in the input terminals of the amplifier. cold end to common, pot variable point to input coupling capacitor and signal between the earthy end and the other end of the potentiometer.
    you can use 50 K for 47K. ( JIS is 25K 50K 100K but western preferred value std is 22, 47, 100)

  167. Seetharaman

    Hi Caloy you can use 0.47 ohms. it will affect the performance of very low impedance speaker as the peak current through the output transistor will get limitted. with speakers of 4 ohms and above it will not matter.

  168. is it ok if i use .47ohm 10 watt resistor for R8 & R9 ???

  169. Seetharaman

    Hi Caloy no possibility at all. The amp will draw the required current only though the power supply is capable of 6amps. Here it is designed for 5mA only, so nothing should happen

  170. is there a possibility that the bc558 transistors will explode if i use 6 amps of current ????

  171. Seetharaman

    Hi Adnan yes you are correct as per calculation. the circuit to which you are going to feed should be capable of handling the voltage, current and power.

  172. if we give 50-0-50v 4 ampere means 400watts of power and suppose our amplifier is of 75% efficient then AC output is 300 watts?is this true or not

  173. Seetharaman

    Hi Adnan the power supply gives the power to amplifier after consuming some it delivers the balance as power output to speaker(efficiency). amplifier power output cannot be greater than power supply capability.
    Hi Mounica in the spec there is a small mistake it should be 4 ohms system 300 watts 8 ohms system 150 watts. if your woofer is 4 ohms, use 4 ohms tweeter in parallel (in phase) with woofer through a non polar capacitor of 5uF if system is 8 ohms use 2.5uF(you can even use ceiling fan capacitor, if non polar is not available). if you feel the volume of tweeter is quite high then add a 22 ohms wirw wound 10 watt pot in series with tweeter and adjust for just matching volume level with woofer, while playing good music.

  174. is there any relation between DC supply power in watts and amplified power in watts?

  175. Seetharaman

    No these analog amplifier’s efficiency cannot be increased. To acheive higher efficiency you should go for class d amplifiers.

  176. can we increase the efficiency of this amplifier?

  177. Seetharaman

    Hi Caloy 0.4 is not a standard value you can get 0.47uF (470n). 39PF is just 39PF only.
    This amplifier though it can be called as class B. it is just class AB push pull amplifier.

  178. what is the capacitance code of 0.4uF & 39pf capacitor???

  179. Seetharaman

    Hi Sagar leave the center tap use the full winding it will be 24volt. use a bridge rectifier and filter capacitot to get 24 volt dc output.
    Hi Adnan yes you can give both the channel inputs at a time.

  180. can i give two inputs (both right and left) at a time???

  181. can i give two inputs(both right and left) at a time?

  182. if i have 12v center tap transformer how can i get 24v from it

  183. Seetharaman

    Hi Caloy with 5 watts the output current can be 4amps continuous with 7 watts it will be 4.6 amps. in fact with audio in it will be only varrying current hence 5 watts is more than sufficient. if you want to drive with sine wave at full power continuous then use 7 or 10 watts. you can use freely available diodes 6A1 four numbers.
    Hi Adnan yes you are correct you can use 2nos 10uF in series to achieve 5uF. (resistance in parllel formula will hold good for capacitors in series).

  184. if 6 amp bridge rectifier is not available…what model of diode should i use???

  185. Seetharaman

    Hi Nightingale first you can start with a variable power supply using LM317 which will be useful for all your projects. then you can proceed with projects using around 20 components and useful for domestic requirements.

  186. Seetharaman

    Hi Adnan it will be limitted to your power supply capability. That is 64 X 4 = 256watts of energy is available. say if the amplifier efficiency is 80% then you can get around 200watts. againg this is dendant on the output transistor capability its thermal conductivity etc.

  187. you tell me last time that if i bridge this amplifier it will give me 900w @ 4ohms but it will require 4 times current and you suggested me 32-0-32v @12amp transformer right but if i use 32-0-34 transformer @4A how much output will decrease in bridged mode?

  188. nightingale

    hey m a first year engineering student,i want to know some initial and interesting projects as i havent studied alot yet..reply soon

  189. Seetharaman

    Hi Caloy you can use 6amps transformer as the requirement is just 5 amps it will be better to use slightly a higher rated transformer.

  190. is it ok if i use 6 amp transformer for the amplifier???

  191. Seetharaman

    Hi Caloy the circuit diagram is correct. component list shows IC as TL084 it should be TL082. C5 is not shown but 220 ohms is shown in the pcb layout, change it to 0.4uF and out put resistance R10 is shown as 100 ohms, it should be 220 ohms. the first photo of the assembled module is correct. the circuit is working ok.

  192. if i make this amplifier two times and bridge them then what will be the calculated output if using 35-0-35v @4A transformer? plz calculate it and tell me and show the calculation that will be helpful to me??

  193. patrick vaz

    Hi Seetharaman,
    Thanks a heap, spot on, except for 2 nos internal resistors of 10K, which can be managed,
    regards & Cheers!!!

  194. patrick vaz

    Hi Admin,
    Pls can u let me know what is the equivalent Transistor for UN4211, Iam new in bangalore (india) and iam unable to find the transistor nor any help from the shop vendors regarding equivalents

  195. Seetharaman

    Hi Patrick BC107 transistor is the equivallent

  196. MR.seetharaman,,,when will you send the pcb layout…i’ve already bought the components…

    i made a pcb layout using double layer pcb…

    will you pls check it….

    will you pls give me your e-mail account and i will send you my pcb layout & check if there are errors……..

  197. MR.seetharaman,,,when will you send the pcb layout…i’ve already bought the components…

    i made a pcb layout using double layer pcb…

    will you pls check it….

    will you pls give me your e-mail account and i will send you my pcb layout & check if there are errors…

  198. Seetharaman

    Hi Adnan for a cross over frequency of approx 3KHz you require 3.3uF for 8 ohms load and for 6ohms it will be around 5uF. 100 volt is chosen to take care of the output voltage swing of the amplifier. capacitor should be in series with the tweeter. the whole thing should be in parallel with the woofer.
    yes i will send

  199. will you plz mail me the circuit of 500watts amplifier with shreya????

  200. you tell me in 2nd last comment to use 5uf 100v capacitor for 50watts tweeter tell me how will i decide the value of capacitor according to input of amplifier and speakers for connecting in parallel same as u tell me?
    is the capacitor connect in series or in parallel?

  201. Seetharaman

    Hi Adnan feed connect the meter in AC voltage range across speaker, feed some loud music to the amplifier. read the maximum AC voltage reached by the meter. this voltage square devided by 6 will give you the power outpur. For getting RMS power you have to feed 1KHz sine wave input and go on increasing it till the sound is clear without any distortion. measure the AC voltage and calculate as above.

  202. Ive made this amplifier using 35-0-35 transformer 2x3300uf 71v capacitors with 2 0.1uf ceramic with 6ohms 150watts woofer
    how can i calculate the output power using multimeter tell me the method plz?

  203. plz send me the pcb diagram of above amplifier and also the power supply circuit?

  204. Seetharaman

    Hi Adnan you can connect you tweeter in parallel with the woofer through a 5 uF 100 volt non polar capacitor.
    Hi Emmi I have replied to your email

  205. i have connected a 150watts woofer for base and i want to connect a tweeter of 50w 4ohms in parallel tell me how can i connect tweeter?

  206. hi seetharaman your given circuit is producing more distortion there is no clarity

    i gave 12v to it

  207. ive made this apmlifier using 35-0-35 transformer 2x3300uf 71v capacitors with 2 0.1uf ceramic with 6ohms 150watts woofer
    how can i calculate the output power using multimeter tell me the method plz?

  208. Jack Daniel

    Hi, Seetharaman, if you don’t mind, can you please provide some details about the power supply which will robust enough for stereo channel?
    Do we have the full specifications for this circuit.
    I am interested to build one for my self.

  209. Seetharaman

    Hi Emmi you can use this circuit befor your tone control circuit. if no tone control circuit use with your sub woofer or 150 watts amplifier.

  210. Thank you for your quick reply

    i have to use your circuit after my Aux circuit or use instead of it

  211. hello today i have sent a mail to you (seethasub at hotmail)

    please check it and kindly send me reply please its very urgent

  212. Seetharaman

    Hi Nidesh it can be TIP41 A or B or C. TIP141 is an NPN darlington not our requirement
    Hi Caloy i will mail you soon
    Hi Shreya the design is getting frozen still some reliability test have to be completed. pl wait.
    Hi Emmi the PCB layout and copper track will be send to you soon