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.




    we also have other types of transformers but with less than 3A, my phone number is +256779268591 please i need your help on this gud time

    • Seetharaman

      Hi Moses use the full winding without center tap of 15-0-15 3amps transformer. It will be 30 Volts. Use one more transformer in the same way in series ensure it gives 60 volts end to end if not interchange one of the transformers secondary winding connection. it will be 60 volts end to end. and use the inter connection between transformer as center tap. Now your power supply of 180 watts is ready. this can easily power your amplifier one channel. do the same for other channel also.


    Hi mr seetharman i have almost made all my connections but my main problem is the transformer. we only have 15-0-15 3A transformer in the market please advise me about this,i also need the pcb connections in my email(alelem@rocketmail.com) may be if possible the videos.thanks

  3. I am looking at this circuit and cannot understand how 2 X 1n4007 diodes are able to bias the output transistors (darlingtons) into conduction, surely you would need at leat 4 diodes, to bias the 4 Vbe junctions? Yet many have built it and say it works well, what am I missing?


    I WAS thinking of using 15-0-15 3A AND 15-0-15 2A in series coment on this sir.

    • Seetharaman

      Hi connecting two transformers in series will increase the voltage but the current will be the same, if they are identical transformers. this is the basic. Please conduct the experiments and give a feed back by using different complex combination of transformers. please check your mail.


    thanks mr seetharman for u reply but there is one thing confUsing me about the transformer coz last time u told me to use 2nos 15-0-15 3A transformer and connect in series and it will give 30-0-30 6A my question is what about the TIP 142 AND 147 transistors which requires maximum current of 5A, WONT THEY OVER HEAT WHEN I USE THOSE TRANSFORMERS IN SERIES SINCE THEY WILL PRODUCE 6A.


    sir i think sending me a full report may also help me understand this amplifier into details.please i need a report for this design on alelem@rocketmail.com thanks


    Thanks alot Mr seetharman for your reply coz you have given me another hope of coming out with what the project requires and i think i need to know how you are coming out with some of this calculations of like the output power, input signal and the output voltage of the power supply.may be on my email;alelem@rocketmail.com, good day sir.

  8. Alele moses

    sir, i was able to get 0.47 5W resistor that you told me about except that i couldnt find the 15-0-15 5A transformer and am going to use 15-0-15 3A TRANSFORMER and i will try to measure the output voltage.what do you suggest about the fuse coz am still using the 5A fuse and am going to use the 6A10 diodes in the bridge but am not going to change other components in the power supply appart from what i have stated above.i hope i shall go to the amplifier after the power supply.thanks alot mr seetharman for your wonderfull work i have already learnt alot even before finishing the project.meet tomorrow.

    • Seetharaman

      Hi Moses you can use 2nos 15-0-15 3amp transformer in series to get 30-0-30 6 amps. with the above power supply and 4 ohms speaker you will get 150 watts output with 8 ohms speaker around 100 watts out put power with an input of 300 milli volt rms signal.


    i have failed to get 15-0-15 5A TRANSFORMER and am thinking of using 15-0-15 3A transformer. in this case what will be the output in volts of the power supply, what about the output of the amplifier in watts,and what will be the magnitude of the audio input.please we have only 3A transformer and less in the electronics shops of our city and thats why i have choosen now 15-0-15 3A transformer thanks, your reply will be appreciated

  10. so i could just slap 5 9volts on this bad boy just to see if the circuit works aye?


    Thanks alot mr seetharman.i tried looking for the 15-0-15 5A transformer but i didnt find it in the all of our city but instead i found 15-10-15 3A transformer and our laboratory technician advised me to use it and determine what it will give at the output of the power supply and my question is what will be the output voltage of the power supply if i use 15-0-15 3A TRANSFORMER, what will be the output of the amplifier,and what should be the magnitude of the audio input,will there be any adjustment in the other components like the bridge rectifier and other components in the amplifier.thanks your respond will be appreciated sir and i hope i will learn alot from this project.


    am going to look for 15-0-15 5A transformer but can i use 6A10 diodes in the rectifier circuit instead of 6A5 thanks.what other alternatives are there for 0.33 ohms 7W resistor coz i dont have them in our electronics shops.

    • Seetharaman

      Hi Moses 6A5 is 6Amps 500Volt PIV rectifier. 6A10 is 6Amps 1000Volt PIV rectifier. you can use. In place of 0.33 ohms you can use 0.47 or 0.5 ohms 5watt if both are not available use two nos 1 ohm 2 watt in parallel. you please send me your mail to seethasub@hotmail.com


    thanks alot mr seetharman for your wonderful work i want to use acombined bass cut and treble out filter please advise me about the connections and if possible send me the details on my email including how to connect it and the circuit including my new circuit and again am having problem of getting a transformer for the power supply am in uganda and today i checked all the electronics shops in our city but i didnt get transformer 30-0-30 5A, i got only maximum of 18-0-18 3A i didnt get 0.33ohms resistior for amplifier but all other components were there except diodes for the power supply instead a got 6A10 and i wanted to use it instead.please advise me about the possible adjustments and if possible the circuit diagram on my email coz i dont want to give up for this amplifier.i also have a maximum of 12-0-12volts power supply in our laboratory and i prefered it instead of assembliong anew power supply please advise me about the possible adjustment for this power supply and the circuit diagram of the adjustment.thanks

    • Seetharaman

      If you can get 15-0-15 volt 5 amp transformer can be used as voltage doubler circuit to feed +40 & -40 volts to amplifier. You can use the dual supply indicated in the following link. That can be adopted for any voltage.

      You can use the passive tone control using TL072 appeared earlier in Circuits today can be used with the above amplifier

  14. Interesting concept. Can you tell me where is it mainly useful? I mean in which cases we can frequently use this?

  15. Alele moses

    i wanted to put this circuit into another use.please help me about this and may be how to connect it for another use.

    • Seetharaman

      Hi Moses please give for what use, then we can suggest.

  16. will it maintain clearity like hi-fi systems,
    plzz reply am thinking to go for dis

  17. moses akwenya

    these circuit schematics are very good for electrical/electronics/computer/telecommunications engineering students

  18. Hi, i want to use this 150 watt amp or your 100 watt sub woofer amp circuit for my car. is it possible. how to convert 12v DC to 36v/45v DC. pls help. if possible send via email. thanx



  20. helow. good to u sir.
    this kind of circuit amplifier, will it work in astereo circuit??

  21. Neeraj verma..

    Plz sir if you have a 12 audio stereo amplifire circuit then plz give me..

  22. Pls sir can dis cct be used as a subwoofer amp? if yes den how…?

    • Seetharaman

      Hi you can use this amp as subwoofer amplifier. feed audio input to the amplifier through the sub woofer filter, appeared earlier as a project in circuitstoday.(sub woofer frequency will be in the range of 80 to 120Hz).

  23. I have try this circuit and it works effectively.

    • yes the two power transistors TIP 142 / 147 need a proper heat sink…

      TIP 41 does’nt need it

      • youngest C

        I used a 450watts-8 ohms speaker bt it rather got blown out. pls wat is the problem?

        • hi youngest C ……
          We have built this circuit about more than 1000 times this works well and perfect..
          If you are facing any type of problems regarding this circuit then you can contact us any time….. we are here for your assistance

          We have a complete tutorial ( images as well as videos ) of this circuit’s building procedure…

          If you are realy willing to built this circuit with perfection then contact us below given mail…. we are here to solve your problems… thanks , have a good day

          • PURSHOTHAMAN

            dear sir
            can we usded this circut as a stereo with the same power supply +45_45 volt ,or any other changes required .please advise in details .

    • Sipirian Simpo

      Ofcourse u need to use passive heatsinks b’se thoz are high power transistors

  24. youngest C

    Pls sir, its just 1 output of the amp, what abt d other speaker? tanks

    • hi ……
      We have built this circuit about more than 1000 times this works well and perfect..
      If you are facing any type of problems regarding this circuit then you can contact us any time….. we are here for your assistance

      We have a complete tutorial ( images as well as videos ) of this circuit’s building procedure…

      If you are realy willing to built this circuit with perfection then contact us below given mail…. we are here to solve your problems… thanks , have a good day

  25. sir pls share PCB lay out and the analysis of this circuit 150 watts.

  26. Soumadeep Saha

    The 33 ohm resistance in the circuit where -45 volts is applied is burning out and glowing red hot… What seems to be the problem…

    • Seetharaman

      Hi Saha It looks like your TIP142 is dead short. Kindly do a cold check of TIP142 between collector and emitter. Anyway check all the connection ensure you start with a DC voltage of plus minus 30volt DC and an 8ohms speaker. If every thing is in order use 45 volt DC supply with 8 ohms speaker. Since this circuit doesn’t have output short circuit protection circuit built in, (as we have maintain least component count)hence use 3amp fast blow fuse initially in positive and negative dc supply line to protect the output transistors. Once the system is healthy replace the fuses with 5amps.

      • Soumadeep Saha

        Thank but there seems to be another problem… I was using another pre amplifier with this circuit and I accidentally opened the connection for negative feedback thus increasing gain and bursting the 100 uF cap…Since then I am getting a voltage from ground…(i.e ground is at a higher potential)

      • Soumadeep Saha

        And can you tell me a test to know if BC558 is fine and also can you suggest an alternative…

  27. Hello every one i have made this circuit it is eorking but the output of this amp is very low even when i onnected a 12″ 150 watt speaker with 30-0-30 l5 amp transformer so could any one tell me how should i get full 150 watt output frm my speaker plzzz

    • sorry in the above comment i have typed 15 amp transformer but it is only a 5 amp transformer sorry for my bad typing

    • Seetharaman

      Hi Sagar what is the impedance of the speaker. it should be 4 ohms with 30volt supply to get 150 watts. input signal to the amplifier should be at least 600mV rms (line level) if it is less add a simple 10 gain pre-amplifier between source and the amplifier.

    • hi ……
      We have built this circuit about more than 1000 times this works well and perfect..
      If you are facing any type of problems regarding this circuit then you can contact us any time….. we are here for your assistance

      We have a complete tutorial ( images as well as videos ) of this circuit’s building procedure…

      If you are realy willing to built this circuit with perfection then contact us below given mail…. we are here to solve your problems… thanks , have a good day

  28. i tried this 150w amp the first time with tip 142,147 and 41c it worked well but it is over heating.however i discovered that tip 41 and 41c are different in value so i am working on that now.

  29. mark magpatoc

    i also want to know if it can work even if the supply is less than 40. tnx

  30. mark magpatoc

    sir , i just want to ask if this circuit can amplify inputs coming form mp3. and if this is mono-channeled


    Sir, Assembled the circuit for 150w power amp,it did not work.we are getting only humming noise. Initially DC supply connected was 17V dc dual supply for try out.is it necessary that max volt to be connected.what may be the reason,out put base voltage is max(13v) on both 142 &147 power transistors.would you kindly let me know the reason also please forward ref.voltages.
    Regards kindly reply\Chandrashekar

  32. Ismael Issah

    Thanks to u guys for the education. l want to try my hands on this Amp (150 W) and want to ask, does TIP141 transistor the same as the TIP142 transistor in this circuit? And therfore can l replace TIP142 with TIP141?

  33. iddy fadhily

    pls mr i need to sarcet diagram sherwood amplifer model no ra-11114t prias help

  34. hi can any one tell me that if i use this amplifier with 4ohm load then ???

    • hi, this amp cannot support the 4 ohm load because it has only two transistor at output.it will overheat on 4 ohm load and will burn.at low bass it will be ok.

  35. Christian

    First of all, sorry if this is a stupid question. But I’m total newbie on audio amplifiers! With that said, now to the question:

    I have a couple IRFR2497, can I use this layout and replace Q1 to Q5 with those? I understand that I might need to have different values on resistors and such.

    Kind Regards

  36. Soumadeep Saha

    i would like to know the wattage of the other resistors

  37. please share the information related to digital storage oscilloscope….

  38. Hi Seetharaman,

    I’m planning to build this circuit. Since I’m going to make a stereo, I need to double the power rating of the transformer. I’m planning to order a 30-0-30 10 or 12A transformer. Could you please let me know if that will be enough? If that’s the case, more importantly, I would also like to know which diode I should use for the bridge rectifier. Can I use two P600A in parallel? what would be the voltage drop?

  39. hi all, i have built this amp 7 times, each time i am left with an amp that has fail each time with +v rising to full psu volts the neg supply dies to 0v. the speaker 0 volts has half volts at this point. the – supply falls to zero. the npn o/p device has on, 3 times blown its guts out. i found a circuit by vellman 100w 200wmp kit and noticed that the 150w amp is a stripped down version of the 150w one. i am a electronic design engineer in the u.k. and notice that using a scope i have found that this design is as stable as a brick in custard, sorry guys, but with all the mistakes in and on the circuit it shoud have been fully noted with corrections and fully tested BEFORE it was issued to the net. i have never found a circuit to SO DODGIE. and released to the public.
    Unless someone can save this amp from distruction each time i conect it to a power supply i would all avvid builders to not to bother with this design. i have used a power supply (dual) +/- 2v to 100v this amp has failed at +/- 15v @6a and it still blow up ? my fear is regardless of layout(s) and i have tried 4 different methods and layouts including one from the original pictures AND IT STILL BLOWS UP?

  40. can i use a 30-0-30 v 8amps trafo for a stereo amplifier?

    • Seetharaman

      you can use but ensure that for each channel positive and negative bus add a 3A fast acting fuse to protect the output transistors against load short circuit as there is no protection circuit included in this simple design.

      • iddy fadhily

        plias tell me oll transistor use for this amplifier

  41. Hi, I’m here to find transistor tip 147!
    The type of transistor, the transistor, which is the same.
    I am Iran
    Two’m Goodbye
    This is just a quick answer.
    Similar tip147 transistor is?

  42. prudencio g.peritos jr.

    I had been adding BD 139 and 140 to my second amplifier with TIP 2955 and TIP 3055 AND ITS WORKING GREAT when i convert to stereo its working great,thank you for this site,I learned and gained more knowledge about amplifier…

  43. dioniz edward

    can i have the data analysis of the circuit because my friend asked me why did i use BC 558 and not other kind of transistor i didn’t find an answer can you help please?

    • you can use other transistor but this is good and cheap.if your friend is intelligent then you can ask to him for other transistor.

  44. Dear sir,I did ​​this ampli but I have a problem, that in the entrance of audio I have a wave signal (12V, f = 1Hz), but I obteint in the output of the amplifier square signal ? why? it’s logic? please advice

  45. prudencio g. peritos jr.

    Atlast i had been enjoy my amplifier using BDW 83c and 84c with Passive Baxandall Tone control its working great. Now i assembled another amplifier using TIP 3055 and TIP 2955 its working great also,,,and i plan to add another transistor using BD 140 and BD 139.,,hoping it will work soon

    • well hello Mr.prudencio g. peritos jr could you post your amp ckt video plzz , i have done this amp ckt but it’s output sound is very low could you plzz guide me( i have used 30-0-30 ,5 amp transformer also but it’s output is less)

  46. Hello again! My TIP41 is overheating and suddenly my R10 (33 ohm) fried/busted. Please help me. 🙁 tnx!

      • Thank you very much, sir! The base and collector of my tip41 was shorted 😀 Sorry for late reply. Now its working! Thanks again!

  47. Can i use 1 heatsink to transistors; tip41, tip142 and tip147?

  48. sir robin just a little bit correction to my email add and this regards with the PCB of the 150 watt power amplifier circuit i am asking to please send me a layout, thank u & more power

  49. 12 December 2010 at 1240H
    a very nice circuit and thank u so much for sharing! by the way sir robin can u pls share me a PCB layout of the 150 Watt amplifier circuit. Thank and please, more power and GOD Bless…

  50. Nice one circuit, thanks for sharing it! By the way cAn anyone send me the pcB layout for this circuit.. Thanks again.! God bless!
    My email – erm.sk8er@yahoo.com

  51. Im having a hard time looking for a 120V to 30V step down transformer for this circuit. Can somone please tell me where I can find these components? Post or send a link if possible please

  52. nitin khandelwal

    what is the basics theory to design such type of circuit?how shall we start to think to built such circuit if we beginer of electronics?…which comp. is required or not?..how can we justify which comp. is connected at perticular place.if i use 4 darlington then what happen if any link there to know about these plz tell me.


    pls sir i need a circuit diagram of audio receive,

  54. hello Mr. Seetharaman
    well i have gone through your circuit and its quiet intresting so i have done it on a pcb but it aint working so could you help me how to check it or what to do plz….

  55. jagadeesan

    Hello Seetharaman sir!
    it very interesting working on this circuit.
    Sir i have used 32v-0-32v 8amps transformer for this circuit you have mentioned to use 30v-0-30 3amps transformer but i am using 8amps wil it create any problem?
    and in this circuit the output terminals from pcb is having 46v when checked with voltmeter when checked with no input,

    • your transformer is ideal for this circuit.after rectification you will get 45v which is good for this amplifier.

  56. Prudencio G. Peritos Jr.

    thanx bro i sent you an email with the link which i got the PCB layout,,,hoping your reply soon with you suggestion or advise

  57. Prudencio G. Peritos Jr.

    You are right Rohin,,when i checked the output with the tester ,i put it at 250 volts,,and i found out that there’s a voltage came out…that,s why the music is not clear…I add some 2 resistors and now the diction is clear alredy..i used 16 sqr inch heatsink because the Q1 is so hot,but the Q2 and Q3 is normal,..can you suggest me regarding this problem, please,.
    I used TURKISH PCB Layout,,,using BDW83C and 84C,,with TIP 41 and BC556…with POWER supply of 24-0-24v,6A…Please suggest me regarding the Q1 is so hot…Longing you reply soon.

    • hi bro, as you said that there is some volt on output so there is some fault in you design. you used good alternative transistor so problem is not due to alternatives transistor.if your q1 is going hot n hot it will blow after some hour.first wash it with thinner then check polarity of all capacitor and good look at ground pin.you please give me link of pcb layout and component list that you used in your circuit because my guess is that you didn’t wrong anything problem due to any wrong component and wrong value resistance.my email id is rohin.sharma83@yahoo.com.

  58. Prudencio G. Peritos Jr.

    Thanks rohin ill check it…and you will know further

  59. Prudencio G. Peritos Jr.

    Sir, i have done already assembled this amplifier, using BDW83c and 84c, it is very loud but the diction or wording of the music is not clear..and Q1 is very hot even I am using 3″ x 3″ heatsink…please help me, what shall I do regarding my amplifier..
    Hoping your reply soon. Thanx.

    • dear bro ,i already made this amp. amplifier is beautiful and clear sound and loud too.it seems that there is something wrong in your amp. R2 should be 220 ohm.if everything is fine then problem is due to alternative transistor.and made this amp as it is.don,t use its updated version where some one put more components like pf and resistance. check the output of amp with multimeter put the scale to dc 200v plus and it should be zero.if there is some volt then you did something wrong.

  60. hello sir i have build this amplifeier with 24v &1amp transformer and there is too much distortion i use speakers of 35 watt 6ohm
    please answer what should i do?

  61. sir why does the sound not amplified?? i change all the transistors that i use. what should i do???

    • if you made it on pcb then pcb may be short one track to another or your flux is not removed on pcb .wash it with thinner or if you made this amp with additional component like pf and resistance then remove them.their is minor fault in your circuit or you fit wrong way any component.

  62. hi sir
    can you please tell me how to convert this amplifier into stereo?

  63. Prudencio G. Peritos Jr.

    hello sir,
    what transistor can i replace TIP 142 and TIP 147?can i replace also

    TIP 41? for matching Q1, Q2 and Q3

  64. i used 45v vdc and i have a pre amplifier connected in a 150 watts amplifier. then i try, the circuit is good and theirs no problem on it . but i confused i try to volume at 50% with a load at input at no power then i turn on the fused blow out together wid tip 142,147 whats the problem on it sir?

  65. HI sir i have a 142 & 147 with amplifier,when i playing this its too hot.can i chenge 142 & 147 to tv’s power horizental transisters like sd1410,sd1550.Please reply.

    • Dissanayake

      TVH-out is not a darlington transistor and it is low current and high voltage drive transistor. You have to try with larger heat sync and cooling fan can apply. in other hand you have to replace 142 & 147 only with darlington types.

    • Seetharaman

      Hi Chhotu The power is RMS voltage available across speaker terminal, V square / speaker impedance. It is clear that for higher power you have to raise the voltage or reduce the speaker impedance. your heating up may be due to higher no signal current for the output transistors, chech the D1 and D2 loop.

  66. sir please tell me how you decide the output power as here you have said its cheapest 150 watt amplifier circuit.

    • Dissanayake

      Basically output power is depending on the supply voltage and impedance of the speaker. P(out) = sqr(V-10)/R.
      V: supply voltage (45v)
      R: impedance of the speaker (8Ohms)
      here 10 is the voltage drop by the darlington.

      you can increase the output power by reducing the R or 10.V
      to reduce the 10V drop you can apply more output darlington in parallely with 0.33/7W resistors.

  67. Good day sir, I built 3 of this wonderful amp without any problem, except for the “excessive heat” of the Darlington pair. I used a fin type 3″x5″ heatsink for each transistor. I know I can use a bigger heatsink but my question is, what causes the Darlington pair to “overheat”.
    Pls. reply to my e-mail…..

    Thanks and more power…

  68. sir i have a 44v-0-44v 5a tranformer . After using capacitor 60v-0-60v is available ,i can use this circuit for this psu?


      hey prithvi, go ahead do not worry about supply. you can use this t/r. but take care that you have to use filer condencer of 75 workig volt.do not forget it.it is better to use instead of 63 woring volt cond.and one more thing ,use 33 ohm one watt resistences as a current limiting resistences to connect positive and negative supply of an amplifier.if you do not use these resistences then both the tr, tip 142 and tip 147 blown off in less than a second. because i have tested this amplifier today.it works well.

      • Dissanayake

        Manohara, applying 33 ohms resistors is not recommended. because the power amplifier is consuming variable current while it is working. so voltage drop across the 33 ohms is variable. Think the amplifier consuming about 1Amp current. so voltage drop across the 33 ohms is (V=IR) 33Volts. the power supply is about 40V the voltage of the amplifier is about 10V. So this is not the right way. Prithvi, I recomended you to increased voltage of all the capacitors up to 70 volts or more. and Vce of all the darlington transistors should be at-least 80V. Vce of all the other transistors should be at-least 120V.

      • thank you for reply .i was waiting for the reply for 3 days after that i tried it from 32vac to 56vac(45vdc-79vdc) from a 550va 8 kg transformer and i used 4 transistor per channel, my two 120mm 8” speaker’s blown . But transistors are fine ,this amp pays back every thing with less hifi quality.

    • Seetharaman

      Hi prithvi all the transistors may blow up. Never use higher than 30 – 0 – 30 Volt RMS @ 3 amps transformer.

      • sir i have asked tis que. bcos i have spent time and inr 2k for making 44-0-44 5a with auxilarary winding 12v 2a transformer . I have used parallel 142 and 147 with no problem or blowing of transistor and i used bc 556 for pre amp.

  69. sir? if rectifier diode in the power supply is 6A05. its okay sir? tnx sir and God bless always^^

  70. Hi samshith,in reply to your request.I am happy to announce to you that i can give you all necessary information you need on this amplifier circuit and other audio system information.I am the MD/CEO of my own electronic fabrication centre,I have trained alot of people and also written some book on sound system and electrical gadget.Should you are interested contact me via my email.

    • akshay kalbhor

      statement: design an audio systm f a fitnes clb f an area 700 sq.feet with glass windows and conseald sealing with following specifications
      instruction mikes,cd/dvd player,appropriate signal conditioning ckt,suitable pre and power amplifier ,7 band grafic equalizer,volume control,tone control,sound level indicator,distortion cancelling ckt,power supply with sht ckt protection and power on indicator,speaker should be column and sealing ,mixed arrangement.

      amplifier enclosure ,half schematic ,sample drawing of sealing and column speaker,connection diagram….

      please let us no it………..by tomorrow….it’s very urgent sir………..help us….it very urgent……….

  71. prudencio g. peritos jr,

    sir, as per power supply diagram c1 and c2 is 4700uf,,,c3 and c4 is 100nf,,,100nf is no available in our market,,,what capacitor shall we replace this 100nf capacitor? please confirm…thanx

    • Dissanayake

      the minimum of C1 and C2 should be 4700uf electrolytic and c3 and c4 should be around 100nf and should be in Mylar type. (68oouf, 10000uf also better for steady current).

      c3 & c4 are acting as high-pass filter and reducing high frequency oscillations in the power supply. any value between 0.1uf (100nf) and 0.22uf (220nf) are ok for c3 & c4 (both c3 & c4 should be same)

  72. prudencio g. peritos jr,

    hi sir, 30-0-30 volts is not available in our market, can i used 24-0-24 volts transformer 6A ?,,thanx

    • Dissanayake

      The supply voltage is important factor of output power of an amplifier. There is no doubt to apply this transformer to this amplifier. only thing is the output power will be low than the given value.



  73. Prudencio G. Peritos Jr.

    Sir, thank you so much for answering my comments… Have a nice day,,,God bless you

  74. Hello sir Seetharaman, I’m from Philippines, Manila I would like to ask if what speaker should I provide building this amplifier using all same active and passive components except that I’m only using 4Amp 30 – 0 – 30 transformer.

    I’ve just build this right this morning and it seems working fine without smoke appears only that I don’t have a speakers yet. I’m a Student!

    Thank You Sir!

    • Seetharaman

      Hi Ljay. You can use 100watts 8 Ohms 12″ full range speaker, in an air tight 65 litres inner capacity enclosure.
      Hi Ray use 6A10 to be on the safer side.

    • Dissanayake

      I tried this circuit with several darlingtons and three way speaker system. also I applied integrated speaker protection circuit to the output of the amplifier. it is recommended to transistor amplifiers because to protect the valuable speakers. the amplifier has very good low frequency (bass) response and it is recommended to apply good low pass filter at the input of the amplifier was trying to oscillating at high frequencies. I thing it is good to apply two way or three way speaker system with good bass woofer rather than a full range speaker. you can also apply a good cross-over circuit for hi-quality music response.

      • Hi,

        Can you pl give the integrated speaker protection circuit diagram that you have added in this circuit so that i can make this circuit as a more efficient one.

        Appreciate your assistance.

  75. Seetharaman

    Hi Prudencio By keeping the flat surface dowm and ensuring that the pins are pointing to you. Left side pin is emitter center top is base and right is collector.

  76. i’m olso interested on constructions of amplifier circuit, but i dont have enough basic obout transistors. i’m doing electronic 2 in computer system engineering. so can you please help me to find more information by sending me some simple circuits to construct.

  77. The designed is ok d output power is recommented.the heating effect is mush as power suply increases what could be done to use circuit at +70 & -70volt look forward to hear from you.mail me dialinton power transistor that can withstand 80volt

    • Hi Togor,concerning your request contact me via my email.I promise to give you better power darlington transistor that can withstand 100 volt and 45 amp.Am MD/CEO of BODNIK TECHNOLOGIE VENTURE here in Nigeria.And i specialised on sound system fabrication.

  78. prudencio g. peritos jr,

    sir, can you give the pin out of this transistor BC 558,the store did not give the pin out,,,im beginner,,,thanx



  79. Seetharaman

    Hi Pankaj 12″ 150 watts woofer is best suited in an air tight enclosure, with an internal volume of 45 to 60litres.

  80. sir can I use a 12inch 150 watt sub-woofer driver with this circuit?????

  81. Hi sir if i build this amplifier in two channel it will work or not? Plz reply..,

    bert from mindanao, philippines..

    Via MebApp.com

  82. samshith triprayar

    sir, i would like to made it. So help me. I want to know capasitor4700uf volt?

  83. Deogratia

    Dear Sir.
    i am happy to get in contact with you, please i need your help concerning this amplifier, When i assemble the amplifier in Mono, it works well, but when i make it stereo, the left channel or right channel will not work, i inter changed all parts from left to right, one chanel still maintain this fault, Please what can be the solution to this? do i need to assemble a split power supply using the same transformer or two transformers for this amplifier, then my second question is that, can i bridge this amplifier to Mono to get more power out-put that can drive my 4 pieces of 21Inches speakers for commercial use? please my email address is(dnkwenti@gmail.com) any help from members here would be appreciated, i am happy to share with good hearth people.

  84. sir please help me I want to use this circuit for subwoofer how can I use it??????
    Can I use a low pass filter??????
    if yes then please provide me the circuit diagram….

  85. Seetharaman

    Hi Spharow with 24-0-24 transformer with 8 ohms speaker the output power will be around 60 watts. You require an input of not less than a signal level of 250 mV. Use a pre amplifier with a gain of 10 to 25.

  86. But having this 24V 0V 24V is not loud enough for me to play my e.guitar?what’s the power of the speaker do I need to use?Or do I need to put preamp before it,plz repz…

  87. Thank you so much, I already found out the fault. The positive line of the of the speaker is shorted unto the ground..tanx..:)

  88. Hi sir, good day.
    If I build this amplifier in stereo it will work or not?
    please reply.
    thank you.

    Via MebApp.com

  89. Benson githaiga

    Hi Sir its my desire to work on this circuit very soon,please send me this page in my email to facilitate my study and reference as i work on the project.thanks God bless

  90. I have done this schamatic but went i combint the p.supply on power Ac…the
    Power ampl. Have sound sudenly for a second sound stop…just hear the voice tottt………

  91. isaac hlengani

    Thanks for the good work,
    Thats very powerful amplifier.
    I’l try to construct it coz it is visible and understandable,
    God bless you keep it up to assist us as student.

  92. hi! sir, can i ask? what is the wattage value of all the resistor and the voltage rating of all the capacitor’s?

  93. Dear Br. Seetharaman…I have 2 requests
    1)I want to assemble this 150W amplifier (TIP142/147)..But from where I can get the PCB layout or readymade PCB kit…
    2)Can u please sent me ur email address..cause I have one old Tone control PCB by Visha electronics..of the circuit published in Elektor India.long back..i think in 80s.I dont have the circuit diagram..if i have ur email address I can attach the photograph of the same for ur kind perusal…I tried a lot for this..pls help me out..
    With hope..

  94. Thats very kind of you sir, you’ve been a blessing to us.

  95. Seetharaman

    Hi Tosin they are power Darlington transistors with freewheeling diodes and currnt limitting resistors. You can fabricate then by using TIP2955/ TIP3055 matched pair (Any High Voltage high power)output transistors with BD140/BD139 (any high voltage medium power)with IN5404 or IN5819 as freewheeling diodes .

  96. I want to know if there are other transistors which can replace tip142, tip147 in the diagram because these ones are not available in my area now. Thanks for the good work

  97. Seetharaman

    Hi John you can use 10KuF 63 volts in each supply line. (both positive and negative voltage). You can always use a higher power amplifier with a little lower power handling capacity speakers, nothing will happen. The other way, the distortion generated by the lower power amplifier can damage the voice coil of the higher power speakers.

  98. prudencio g. peritos jr,

    thanx a lot sir,,,MAY GOD BLESS U

  99. is it ok if i used a 80 watts amplifier to 150-200watts speaker ??? thanks

  100. can we use a 10k uf 63 volts capacitor in the power supply?

  101. Seetharaman

    Hi Rusty TIP41 is NPN, which is required here. TIP42 is PNP with which you will blow the output transistors.





  103. Seetharaman

    Hi John no need to use screws just slide on the clip.

  104. Seetharaman

    Hi John it is a must, for TIP142 & 147 you require a large extruded alloy heat sink. for TIP41 a clip on will do.


    Good day , I have Query, Ive biult the 150watt amplifier but have a problem. In the write up it calls for a TIP42, but in the diagram it calls for a Tip31. when I connected up with Tip42 r4 burnt up including Q4 & Q5. on replacing them it burnt Q2 ,Q3 Q4,Q5 R10, c2.
    I had a30volt supply. could you throw some light on this.
    Regards Rusty. rhearder@intehom.co.za

  106. heatsink for the three TIP are needed??? please answer thanks

  107. Seetharaman

    Hi Prudencia please refer my earlier comments on this
    December 15, 2011 at 9:46 am

  108. prudencio g. peritos jr,

    hello sir. as per diagram Q1 is TIP 41? or TIP 141,,likewise the capacitors ,the volt was not given for every capacitor listed in diagram,,,

  109. heatsink is needed for tip142 tip147 and tip41 ??what kind of heatsink is it??
    Thanks seetharaman..
    Pinoy ako

  110. Seetharaman

    Hi Many connect a 22k or higher value potentiometer for volume control. Connect one end to 0 volt line and the other end to input and potentiometer’s center pont(slider) to audio in of the amplifier.

  111. tnx seetharaman, i using for my mobile sound system big horn tweeter if you have more compatible amps for tweeter can i request more fabor.

    Tnx and more blessing to you and CT….

    Respectfully yours,

  112. how are you to connect the variabel resistors to vary the volume

  113. Seetharaman

    Hi Gilbert reduce C2 from 10uF to 1nF. Add a 47PF from Q3 collector to base. Why do you require so much for tweeter power?

  114. Sir Seetharaman
    A nice day, if I use for tweeter power amlifier this circuit what is the modification.
    Tnx alot Gilbert…

  115. Seetharaman

    Hi John with low value potentiometer while it is set at extreme ends will get burnt, hence a fixed resistance is preferred.

  116. Seetharaman

    Hi John you can use 3nos 1 ohm 2 watts (which is standard and freely available)resistance in parallel to get 0.33 ohms 6 watts.

  117. what if r8 and r9 is not available in the market ? what should be replacE ?thank !

    from the philippines PINOY !

  118. Seetharaman

    Hi all capacitors should be 50volts or higher

  119. in this schamatic 150w ampl. the all capacitor did’t swo how much volt u can put?c1,c2,c3……including the power supply c1,c2,c3,c4…..all this capacitor did’t swo how much can put?pleeeseee…….imfom. me…this ergent!!t.Q…

    can i use 6A in transformer > the value of others will affect ? help me tnx

    • Sipirian Simpo

      The pins for the audio output of any audio system. E.g Radios, mp3 etc

  120. how many watts in R1 , r2 , r4, r6 , r7 and r10 ..thanks



  121. seetharaman sory for asking you a lot of cuestions but i measured 75watts into 8 ohm load.if i use two pairs of tip14x conected in paralel i will take 150watts rms ito 8 ohms?thanks for your help!

  122. Hello sir I am having some douts…….
    1. I am having a (24 w 4ohm)*2 speaker,is dis circuit suitable for powering it
    2. Normally in stereo circuit we hav 2 inputs (R&L)but in dis circuit i can find only one.. So do i hav to make 2 circuits for stereo output I.E (150w circuit * 2)?..

  123. hi sir i made this circuit.its working grest!!can you sugest me a tone control circuit for this amp?

  124. seetharaman

    Hi Rush you can use two capacitors in parallel. it will suit. you can use ceramic or polyester capacitor rated for 50volts or higher

  125. Hi sir,

    Plz suggest me about query posted on February 13, 2012 at 8:12 pm

    thanx a lot

  126. Seetharaman

    Hi Spharow check the bias diodes D1 & D2 direction, the end with a white band is cathode.
    Have you insulated Q1 & Q2 from heat sink with proper mounting kit.

  127. I’ve assembled it but the moment i run it, the wire from power supply(+) is melted and burn the wire..(0) is on the ground and (-) is on the collector of tip147..I’m just using 24v 0v 24v..what’s the problem?I’d rechecked it over and over again but the circuit is just rightly connected..

  128. Hi Tmaxx226,
    The 300VA transformer should do just fine for the stereo application, but I recommend using the 500VA instead, having a little more power than recommended is always better in amplifiers.

  129. any circuit available which converts from 60 W audio o/p with 16 ohms res to 150 Watts 16 ohms.

  130. seetharaman,

    Will a 300VA 30-0-30 toroid transformer produce enough power for a stereo application of the amplifier? Or would it be best to use a 500VA transformer? Thank you for the help!

  131. Hi Sir,

    I have done my 150W amp as per ur instructions and its working gr8.

    Sir, now i going for subwoofer low pass filter shown in https://www.circuitstoday.com/subwoofer-amplifier

    But, as per ur suggestion for 0.18uf(C1)we can use 0.1uf & 0.082uf in parallel. So,please let me know which type capacitor i can use for 0.082uf? Is it disc type?
    Thanks again…………. Have a nice day..Happy valentine day….

  132. Hi Sir,

    I have done my 150Watt AMP as per your instructions and its working fine.

    Thanks for your help.

    I want to assemble subwoofer low pass filter shown in https://www.circuitstoday.com/subwoofer-amplifier
    But, i didn’t get 0.18Mf(C1)in market.So,
    As per your suggestion for 0.18Mf we can use 0.1Mf+0.082Mf.
    So, please let me know 0.082Mf is which type of capacitor? Is it disk?

  133. seetharaman

    Hi Jam +45volt should get connected to TIP142 collector and -45volts sholud get connected to TIP147 collector. zero should be connected to terminals shown as earth. (speaker’s one end, C3, R7 and input common terminal)

  134. hi sir, just wanna ask.. on the circuit proper, where should we connect all of the ground? and also, should the -45V be connected with the grounds as well? pls reply. thanks.

  135. One last (possibly stupid) question.
    I’m making it with 2n3055/MJ2955 darlingrons. Their rated power is 116W 60V 15A, the rating of the TIP147/142 is 100V 10A 125W, so will there be any drop in the output or will it increase/remain the same (my guess is drop)? Or will the output impedance handling change? (Will be used as a driver for a sub, the sub is 250W rms 4 ohm). I’ll be using a 45-0-45 ~10A supply.
    Thanks in advance.

  136. I assembled two units for stereo but every time i test it, one unit blows!!! I tried to separate their power supply but still the same…( I already busted 10 pairs of TIP142 and TIP147) I continued troubleshooting but I can’t find any defect in the circuit,The latest part replacement of the Darlington pairs were OK, I guess I must have bought fakes TIP 142 & 147….
    The sound is good. I used this this Ckt. to drive my Subs and center speakers….. I’ll send some pictures later….

  137. seetharaman

    Hi Rush the PCB shown is perfect the layout is also correct you can go ahead.
    Hi Panos the maximum output with +42-0–42volts DC can produce 200watts into 4 ohms load.
    Hi Noel 4700uF can be 63volts DC or more. C1 & C2 & C3 can be 25 volts
    HiToC use 2N3055 MJ2955 with BD139 and BD140 as darlington.

  138. 1. can’t u give the condenser What volt in use=4700uf ?v
    =C1,C2=10uf ?v
    =C3=100uf ?v
    2. the transformer 5A can use more then 5amphere?

  139. Will this work, because i’m too lazy to go out and buy the TIP142,147 now, won’t making it with 2n3055(I know 2n3055 is not darlington but I’ve added another transistor to make it like that also without the other transistor it will work too) darlington do it? (of course 2n3055 with MJ2955)

  140. hi ser,i am panos from greece and i want you to tell me the maximum rms watage i can take of this amplifier.

  141. samshith triprayar

    hi sir,
    i try this amp. I’am very sad this is not woking.
    D1 and D2 and R5and R3 is very very hot

  142. sir .. for this circuit that you posted is it necessary or do we need to add an preamplifier ? if yes how ? thanks

  143. Sir….. If i using +/- 50 volt DC power supply its need to be change R6 value??

  144. sir can i connect another pair of tip142 and 147 in a parallel connection. what will happen the rms will be increases? thanks

  145. seetharaman

    Hi Rush007 TIP142/147 pair output is limited to 150watts maximum into 4ohms load with +35 0 -35 volts DC and around 100watts into 8 ohms load with +42 0 -42 volts DC.
    BDW83C/84C 150watts into 8 ohms with +52 0 -52 volts DC and 250watts with +48 0 -48 volt DC.
    Since peak current is going to be quite high layout and the gauge of wire used are very important. Please take care.

  146. Sir….. actually i want 150Watt RMS(on 8Ohm)& 300Watt RMS(on 4Ohm).
    can i get this by using BDW83C / 84C pair.

  147. Sir…How many RMS output can i get from this circuit for 4Ohm/8Ohm woofer with using BDW83C / 84C pair instead of TIP142/147 pair which suggested by you. Have A Nice Day.

  148. Seetharaman

    Hi Rush007 no need for any other modifications, just replace the output transistors with a good heat sink.

  149. Thanks very much Sir………but let me know what changes needs to do in original 150W circuit with BDW83C / 84C. Have a nice Day……

  150. seetharaman

    Hi Rush007 you have to use >150 watts amplifier for good transient with 150Watts speaker (always use an amplifier with a speaker with less capability, with higher capacity speakers the amp distortion will be transferred to speaker and damage it) . Use DC 50-0-50volt 3amp power supply and use BDW83C / 84C pair for the output, with good large heat sink.
    you can use the sub woofer filter appeared in our projects
    No PCB layout available you may use standard universal boards.

  151. Thanks for response sir…..Request to you please give me suitable sub-woofer filter or sub-woofer output pre-amp circuit diagram for this 150 watt Amp.

    And sir what is the recommended sub-woofer and DC +/- Volt for this 150 Watt circuit because my requirement is to use 12″-150W-8Ohm Sub-woofer.

    Thanks Again sir….. And Wish u Happy New Year.

  152. seetharaman

    Hi Basi +40-0–40 volt DC not AC. AC 30-0-30volts
    Hi Rush007 you can use with a suitable sub woofer filter or the sub woofer output of pre-amp / amplifier

  153. Sir, Can i use this AMP for my sub-woofer(12″-150W-8Ohm)

    Please suggest me..Thanks.

  154. Hai seetharaman..
    Plz help me..
    I have used irf250 4 mosft pwr amp volt why..?

  155. Bryan Laroya

    thank you sir seetharaman……….,i will do your advise…

  156. hi, sir thanks. the circuit was great. but if you use 8ohms speaker the output of 150watts rms, it become 75watts rms. in mono. thank you sir you are great.. if you have a 1000 watts rms pls send me thans hers my email normzhie@yahoo.com

  157. Malik Umair Latif

    Specify the speaker, How much inches?

  158. seetharaman

    Hi Bose you require smaller clip on heat sink for Q3, and extruded alloy heat sink of around 16sq inches for output transistors Q1 & Q2.

  159. seetharaman

    Hi Bose you can use 0.47 ohms 5watts resistance. for 4 ohms speaker better use 0.33 ohms, this can be achieved by using 3nos 1 ohm 2 watt resistances in parallel.

  160. sir i dnt get the resister 0.33 ohm what can i do ,can any other resister is enough or else .33 ohms is required
    thank u,

  161. Seetharaman

    Hi Bryan it is working great. please go through all my comments. Q3 should be TIP41 NPN transistor.

  162. Oops, finally it was working awesome….
    But there was huge distortion when connected (just connected but not played any music ) to the computer output directly without a pot.
    Is it normal with this Amp or is there any mistake in my construction. I have used 10000uF caps as filters.

  163. And I was also tried with 24-0-24 transformer, but the problem still exists.

  164. Hello sir,
    I have built this circuit, but when I have checked the output voltage it was displaying around 110 volts at 0 input signal btw I was running on 40-0-40 transformer. when I have connected my subwoofer the diaphragm coming out from its neutral position and stays over there until I turned off the power supply.
    I have rechecked the circuit many times every thing was ok, and replaced all transistors, but the problem still exists.
    Any idea on this.?

  165. bryan laroya

    sir can you clarify the Q3?….cause in diagram its TIP41 but in the description above its TIP42!…thats all sir!!!tnx……..





  168. Seetharaman

    Hi Pekka Langer you have to use 30-0-30 V RMS AC @ 5 Amps secondary transformer of good quality.

  169. Pekka Langer

    And i got it wrong again… not 60-0-60vac.

  170. Pekka Langer

    Sorry. i meant 30-0-30 vac and 60-0-60 vac

  171. Pekka Langer

    i was thinking about rewiring the secondary on a microwave oven transformer, how many amps would the new cable in the secondary need to be rated for 35+35 vac.
    5A on 35vac or 5amp on 90vac ?
    a fitting transformer around here would cost about 100euros

  172. seetharaman

    Hi JRY all ceramics as per PCB are required for the stability of the amplifier. The circuit is the basic one for good quality components and layout. since both are not practicable you have to add these components to avoid the shortfalls

  173. Thanks Seetharaman! That did the trick, I love this amp, works perfectly.

  174. @ seetharaman base on your schematic dia. you have C1 TO C3 but on your pcb layout you have C1 TO C11,, ceramics is not included on your schematic dia. it is nessesary or not

  175. seetharaman

    Hi Tomy it looks like crossover distortion. may be at high volues it is sounding clean and at low volumes it is having distortion. If this is your problem, when your out put transistors are highy mismatched this happens, you can reduce this by measuring the output tansistor collector (any one) current and raising it to 50mA, if it is too low by including a 1/2 watt resistace of 10 to 27 ohms between D1 and D2 such that you achieve the results. do not exceed 75mA.

  176. Hi Seetharaman,

    I really like the simple design of this. My problem is distortion that is coming out if I try to lower the input signal with any resistors. I’m using this amp to power a 4ohm subwoofer. I have the amp connected to a line level low frequence output of my main amp. I put this amp together based on the exact components that you recommend. I connected 0V to the chassis ground (close to the transformer). I have also connected input common to the same ground point. I’m using 16gauge or larger wires and bus perf board. I can not hear distortion if I don’t use any resistance on signal input. If I try to put 3K normal resitor or 50k pot to the input signal, I get distortion. I have also tried to connect 220PF and 1000PF disk capacitor between the input signal and ground, but no effect. I’m doing probably something obvious wrong, but I just can not understand what that is…

    Your help would be highly appreciated.

  177. thanks also to SEETHARAMAN for the ground detail..
    this amplifier is 100%

  178. This design actually work..
    I followed every steps and it worked..
    I have now an amplifier that has a very clear output.

  179. seetharaman

    Hi Joy AC RMS X sr. root 2 will be the DC output without load (DC output = V RMS X 1.4.14). With load it dpends on the regulation of the transformer. hence with 32-0-32 you will get 45-0-45 volts DC.

  180. joy thomas

    Hai seetharaman

    I woud like the 100 watt rms Poweramplifier, I can use 32 0 32 ac out put transformer, how much dc volt will come the rectifier out put.

    thanking you

  181. seetharaman

    Hi Johnda ground should be connected to 0 volt reference supply as there are both negative and positive voltages are used to energise the amp. please refer to amps power supply circuit

  182. seetharaman

    Hi Navales you have to use only darlington transistors in this circuit. with regular transistors it will work in low voltage as you raise the voltage the no signal current will increase to full rating and beyond and destroy the output transistors. you have to adjust bias etc, which is a the basics. try to use the published circuits as it is for positive results as the published circuits are well tested.

  183. I have changed the 2 power transistors to a1904 and 5198, a 500 watts power transistor of KONZERT amplifiers then it works to a supply -12 o +12, but during the time I powered it into a -30 o +30 volts… 5A fuse blows… now my question is… what is the difference of tip darlington pair transistor among other transistors? if there is a replacement for that tip transistor that is cheaper than tip… can you please tell me or send it to my email..navalesaryan@yahoo.com. i need your help… thanksssss… your reply is highly needed and appreciated. good afternoon.

  184. uhhmm…
    im still new in making amplifiers..
    my problem is the power source..
    where would put the ground?
    I think its not in the negative

  185. in this schamatic 150w ampl. the all capacitor did’t swo how much volt u can put?c1,c2,c3……including the power supply c1,c2,c3,c4…..all this capacitor did’t swo how much can put?pleeeseee…….imfom. me…this ergent!!t.Q…

  186. plese send 2000watts rms amplifier circute diagram
    my mail id

  187. seetharaman

    Hi Vash you please refer to my sept 17th comment that site gives you the updated modifications and layout, use them for your success.

  188. can anyone send me a layout on this circuit because i have still dificulties on it i already troubleshoot it but it’s still not working

  189. hi

    plz never minde i have not understand in english.
    plz give me a woofer circuit 200w
    easy circuit
    and power full bass controler
    and max speaker 8″ +5″*2
    Thanx all

  190. seetharaman

    Hi NKWENTI there is no protection circuit available for this simple amplifier. you have to take care of speaker impedance(not less than 8 ohms), peak DC supply voltage(+40 and -40 volts should not be exceeded at any time) and loose contacts in speaker connection. you cannot bridge, any mistake will destroy all the transistors may be rectifier and power pack also may blow off.

  191. Hello.
    I found this site interesting about this amplifier. My problems with the schematic is this, After i assembled the power amplifier in stereo mode, only one channel was working, the other channel only humm and only the TIP 147 gets hot, but as for the other channel, it gives me good sound, also why is it that the amplifier gets damaged very fast??

    Then please i am really interested to build this amplifier in bridge mode, can i just build the amplifier and bridge it just like how TDA 7294 is bridged?? can i please have a simple circuit for speaker protection that can be used with this amplifier??
    Any support will be appreciated.
    Thanks all

  192. Hi Admin thanks for response the thing is on the output even if I connect them together the positive and negative polarity no distortion sound comes. It should make a disortion sound if amp is alive I think.

  193. Riyazzkhanzz

    I like the circuit and i like to build it in stereo.what changes should be done in the power supply(ie;Ampere of the transformer).

  194. hi….since i completed my amplifier,every time i connect 2 60watts speakers i always experience a hum sound whenever i turn the pot to the end but when i only connect one 60w speaker,it does not occur.what should be the problem and what should i do because i really need to connect the two speakers???please help…

  195. HI ALL
    IVE CLEARED ALL MY PROBLEMS WITH THIS ONE CANT USE A 10K POT ONLY 1K INLINE TO AMP AND IT WORKS GREAT I DIDNT BELIEVE THE SCHEMATIC AT FIRST THATS Y I DID IT TO CHECK FOR MYSELF IM SURPRIZED ITS ACTUALLY A POWER LITTLE AMP FOR THE MONEY IF SOMEONE WANTS A PCB EMAIL ME(ejhgbb@gmail.com).instead of bc558-bc556 transformer 36v-0-36v regulated 50v,otherwise all the rest by the book.txs for a great sight and txs mr SEETHARAMAN for the power supply circuit u send me.
    cheers john

  196. I did this amp but instead of bc558 I used bc556 and I connected a 10k pot but its not working correctly lot of hum I’ve done a few amps with success but this one has me puzzled,are the bc556 the cause used a 36- 0 36 volt trx,iu know its low but even if it pushes out 50w I’m happy.what could the problem be any help pls. When I measure output volt on speaker line I get 42ma but as I turn the pot it goes to 200ma plus then down again.at full volume not bad but down bad. Help pls

  197. Hi seetharaman
    i just got the Tip 142 and i am don with this circuit.it is working perfect for me,i love it.
    SEETHARAMAN i must say i am greatful for your asistance.
    Pls can i get the circuit diagram for 12volt car amp with a output of 140watt,pls i need this one so bad.
    I will be waiting tanks

  198. Its a very simple but effective amplifier,completed mine about a week ago and it works great.But the speakers i have are only 60w so instead of putting 220ohms i put 2k to retard output and improve the stability.

  199. hi seetharaman.
    Pls want the resistor that can step down 25v,15v and 12v to 3v and 5v pls.
    I will be waiting tanks.

  200. admin

    Reply to ANDY

    2200 uF/ 16V capacitors are not at all sufficient

    Use the one i shown in the power supply circuit

  201. seetharaman

    Hi Cooldon kindly list what is available in your market (even it is not Darling-ton transistor) then i can suggest.
    Hi Vysakh is correct use with 50 volt DC rating.

  202. check your rectifier output. If need please add 4700mfd capacitor for filtering

  203. I am hearing alot distortion. Is this maybe because of the capacitors that I used to the rectifier. The caps are 16v 2200uf.
    Any help please?

  204. it’s a simple but huge power amplifier, nice…..

  205. Hi seetharaman,
    I am jst coming back from the market,i still can get 2SD2390 (2SB1560,Pls help me i need to biuld this circuit.
    I will be waiting,

  206. seetharaman, i’ saw the reply tanks every much

  207. WINSTON,i most say tanks man.i am so much greatful

  208. seetharaman

    Hi Winston you can use 0.5 ohms 10watts. Maximum voltage is plus minus 45 volts DC. 32-0-32 volts @3amps maximum for unregulated supply.

  209. hi…i was wondering instead of using a pair of 0.33ohms,can i put a pair of 0.5ohms for replacements.And what is the maximum voltage for amplifier?please reply i need to conclude.

  210. seetharaman

    Hi Cooldon you can use 2SD2390 (2SB1560 is the PNP pair of this) as replacement. in place of 1.5k one 1k and 470 ohms in series or you can use 3.3k in parallel with 2.7K if available.

  211. Hi somebody,
    Hi everyone,
    am cris from JOS IN NIGERIA.pls i need somebodys asistants pls.i want biuld this circuit.but when i went to the market to buy the parts they dont have R1 1.5 and Q1 Tip 142 pls i want the replacement for this componet.pls send it to my email,youngcooldon@yahoo.com