Description.
This is the circuit diagram of a fully transistorized sub woofer amplifier that can produce an output of 100W.There are seven transistors including four in the output stage. The transistors Q1 and Q2 form the preamplifier stage. Transistors Q4 to Q7 form the output stage. Since no ICs are used the circuit is very robust and can be easily assembled on a general purpose PCB.

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Circuit diagram with Parts list.
100-w-subwoofer-amplifier-circuit

Notes.

  • The circuit can be powered from a +35V/-35V, 5A dual power supply.
  • Use a 100W, 12 inch sub woofer at the output.
  • All electrolytic capacitors must be rated 100V.
  • The transistor Q4 to Q7 must be fitted with heat sinks.
Author

800 Comments

  1. Seetharaman

    Hi Rohin check your email for my detailed reply.

    • hi, sir i have 150 watt, 8ohm, subwoofer ,its support to 4.1 home theatre audio board ???? once its can’t supprt then wich type of audio board i can use plzz tell me sit

  2. dear sir,i made this circuit but not working when i connect it to woofer R15 is burning please help me as soon as.waiting for your reaply

  3. J S Nagaraj

    Please confirm me wether this blog is genuine or wether this website is a fake

  4. P.Srinivasan

    Dear sir , i planned to keep the this amplifier kit ( including power supply unit ) into the sub woofer enclosure inside, there is any problem if woofer and transformer in one box ,

    SUB BOX DIMENSIONS KFC-W3013
    Sealed box volume 35.4 Litres
    Sealed Box Dimensions 475 x 362 x 299mm (19mm thick MDF)(WxHxD)
    Vented box volume 56.6 Litres
    Vented Box Dimensions 590 x 362 x 355mm (19mm thick MDF)(WxHxD)
    Port dimensions (labyrinth) (W x H x L) 38 x 324 x 546mm

    please advise me

  5. J S Nagaraj

    Mr. Srinivasan, there won’t be any considerable problem because most of the
    2.1 channel amplifiers contain transformers in them but try to keep a bit far from the speaker.Try to shield the transformer if not leave it as it is.

  6. J S Nagaraj

    Sir, Mr.Seetharaman
    I am not finding an exact input buffer and tone-control circuit for
    my STK4141 II amplifier board. Please help me with TOTAL amplifier circuit of the same.
    Thanking you,
    J S Nagaraj.

  7. P.Srinivasan

    Dear sir , i planned to keep the this amplifier kit ( including power supply unit ) into the sub woofer enclosure inside, there is any problem if woofer and transformer in one box ,

    SUB BOX DIMENSIONS KFC-W3013
    Sealed box volume 35.4 Litres
    Sealed Box Dimensions 475 x 362 x 299mm (19mm thick MDF)(WxHxD)
    Vented box volume 56.6 Litres
    Vented Box Dimensions 590 x 362 x 355mm (19mm thick MDF)(WxHxD)
    Port dimensions (labyrinth) (W x H x L) 38 x 324 x 546mm

    please advise me

  8. Seetharaman

    Hi Srinivasan you can use. once amplifier distortion sets in above 100watts the speakers voice coil will be damaged over prolonged operation.

  9. P.Srinivasan

    can i use 4 ohm kenwood woofer (400w rms power )for this circuit ????

  10. anwar sadath

    sir,
    i’m an electronic student.
    can you send me the circuit of 35/-35,5A dc dual power supply for 100w subwoofer amplifier?

  11. Pls send me the circuit for 2.1 home theatre for computer

  12. can i have the PCB shceme of this circuit ! my mail

  13. Kuttymani

    Hi sir
    I am a electronics student. How to assemble the (2000watts) 5.1 hometheater. Send to the subwoofer board name, transformer ( volts & amps), volume knob value, and etc… Assemble procedure mention tamil. Please send me…
    My e mail id : Pmanidece90@gmail.com

  14. Kuttymani

    Hi sir
    I am a electronics student. How to assemble the (2000watts) 5.1 hometheater. Send to the subwoofer board name, transformer ( volts & amps), volume knob value, and etc… Assemble procedure mention tamil. Please send me…

  15. seetharaman

    Hi Sairam you can use 4 or 8 ohms with 4 ohms the wattage will be 150 and with 8 ohms 75watts.
    Hi Shashidhar C1 is ceramic or polyester. C2, 3 &, 4 are electrolytic and C5 is ceramic tubular or disc. all capacitors are rated for a minimum of 50 volts.

  16. sir how many ohm should the subwoffer speaker should be used in this circuit

  17. shashidhar

    sir i have a doubt which capacitor to be used in this circuit whether ceramic titanium or electrolytic capacitor how can we know which to use in the circuits

  18. hey shraventh, i have built it and works wonderfully, for more info check all the comment posted from the begining and built it exacly how it says

  19. hello,sir plz send me 100w subwoofer pcb design.

  20. Seetharaman

    Hi Kaifpkm you use with the systems sub woofer output. if you do not have any sub woofer output from your system use a sub woofer filter project appeared earlier.
    Hi Arc use 1/4 watt for resistors, which has no wattage indication. For Q3,4 & 6 use a versawatt cooling clips. For Q5 & 7 use an extruded alloy heat sink not less than 12sq inch. Cooling fans are not required. If you use a torroidal core transformer even transformer will not get heated up.

  21. sir… is nessocery any filter board at input section

  22. arc_reactor

    helo sir, all resistors should be from 1/2 to 1 watt? transformer be on a heat sink or any kind of cooling system like DC fan? sir pls help.;’ tnx in advance’.;’

  23. M.M Yogesh

    actually there is a doubt to every body that what ratings sholud the power supply be…. (it is supposed to be 25-0-25 volt ac sec. supply…. and (mic6A14 diodes)…. and (4700uf/63 volt capacitors) should be used….. the output connected to a 100watts speaker sounds perfect….(MAKE SURE THAT Q4 TO Q7 SHOULD BE PLACED ON A MULTI FIN HEATSINK WITH HEAVY WEIGHT…… I WILL ALSO TRY TO PUT ON A SPEAKER PROTECTION CIRCUIT IN NEXT UPDATES….. THANKING YOU..:)

  24. krishna kumar

    i want pcb design of this 100 watt subwoofer amplifier

  25. seetharaman

    Hi Uday you can use a standard 24-0-24 volt 3amp capacity transformer with 5amps brodge rectifier and 4700uF 50 volt electrolytic capacitor and one number 0.1uF 63volt disc capacitor for positive and negative supply. (please refer to 150watts amplifier circuit for the power supply details)

  26. getting 35v d.c is the problem i am facing can you help me pls sir.and i did audio amplifier using this sight and its perfectly alright and working thank you

  27. seetharaman

    Hi Amar In place of 0.33 ohms (if not available you can use 3nos 1 ohm 2 watts in parallel) you can use 0.47ohms 5watts. In place of 560pF you can use any value from 100 to 470pF.

  28. Amar saigal

    can i use any other resister instead of R14(.33 ohm 5w)
    can i use any other capacitor instead of c5(560pf)

  29. arc_reactor

    sujeesh, try using a 100 watt speaker. check your power supply first; polarity of the rectifier diodes and the capacitor, replace R7 and check the components one by one. as stated above, all electrolytic capacitors should be at 100v. make sure that nothing is shorted. test it again first with a multi tester to see if you have an output then connect the speaker.

  30. hello sir,i didn’t got any reply for above comment

  31. Sir, i made this circuit when i tested this circuit with 8w,4 ohm speaker the resistor R7 starts burning.i made power supply with 27,0,27 transformer, 4,6A Power diodes and capacitor rates 4700 uf/63v. can you identifi what is the problem? Can you help me please?

  32. seetharaman

    Hi Sjees DC output from a full wave rectifier with filter capacitor will be V RMS of the secondary of the transformer multiplied with root2 (1.414 times). current rating will not change.
    Hi Kanmaa you can use 9amp transformer. your current requirement is only 2 to 3amps. if you use 9amps ensure that you provide fast acting fuse of 4amps for positive and negative rain. in the event of short circuiting speaker leads will not blow the output transistors as they are like to dissipate 400watts which is beyond their apability.

  33. I WANT TO KNOW ,IS THERE IS ANY PROBLEM IF WE INCREASE THE TRANSFORMER RATING FROM 5A TO 9A,IS THAT OK?,WILL THE AMPLIFIER WORKS SMOOTHLY?

  34. Thank you for your last comment sir,
    i want to know that what is the ratio or any eqation to find what is the rate of voltage increase for rectifiation and filtration,after these process,what about current? Decrease or increase?

  35. seetharaman

    Hi Sujeesh you require a DC voltage of +35 – 0 -35 volts at 5amps. Since the capacitors will be charged peak voltage, 1.4.4 times the RMS secondary voltage of the transformer. Hence you have to use 35 / 1.414 volt RMS transformer. That is 25-0-25 RMS secondary transformer rated for 5Amps. 27-0-27 will produce +38 -0- -38 volt DC. Can be used. Your peak power will be little higher, around 150 watts into 4 ohms load. but getting a 25-0-25 transformer is easy because it is a standard voltage 27-0-27 you made to order.

  36. Hai,
    i made this circuit and i want to make a power supply,i heard that when rectified voltage will increase. If so which transformer i want to choose? 35,0,35 5A,or 27,0,27 5A. Which is more efficient?
    Can you help me?

  37. Hai,
    i made this circuit, and i want a transformer.i heard that when rectified, voltage will increase. If so 35,0,35 5A or 27,0,27 5A transformer i want to choose,which is more efficient? Can you help me?

  38. seetharaman

    Hi Sinoj SWG is standard wire gauge. this represent the charector of the wire it dia current carrying capacity etc. (please refer to SWG Tables. A coin wound on a bare plastic former or without anr core material.

  39. Hi,
    what is mean by 16 turns and 22SWG air core coils in the transmitter circuit. What is SWG

  40. seetharaman

    Hi Sairam Without polarity and values up to 0.47uF you can use ceramic. from 0.1uF to 2u2 you can use polyester paper etc capacitors. 4.7uF and above use electrolytic capacitors, they are polarized hence take care of polarity while connecting. Here C5 has to be ceramic, C1 can be ceramic or polyester. others are electrolytic capacitors. For high frequency, coupling and decoupling use ceramic.

  41. sir i was asking about 100watts subwoofer please tell me wat capacitors should be used for c1,c2,c3,c4,c5 how can we find in circuit tat we have to use ceramic or electrolytic capacitor

  42. sir please tell me wat capacitors should be used for c1,c2,c3,c4,c5 how can we find in circuit tat we have to use ceramic or electrolytic capacitor sir please email me this information please please please please

  43. sir one more question i wanted to ask u …..
    is there any way to utilize telephone line’s voltage to operate a DSL modem????

    can we obtain 9 volts from our telephone line?

  44. seetharaman

    Hi Omer if you are taking up audio as your project you can use motional feedback amplifier project which will be new for the present eneration. go through the project details and if you have any doubt please donot hesitate to contact me,

  45. hi sir seetharman…….
    now i m in final year of BSC
    ((electrical engineering ))……..
    wilL u plz help me in deciding the final project ??
    please & if the project is related to sound systems in addition with other features n functions????
    plz give me some idea?

    i want a standard project …….. πŸ™‚
    i hope u’lL help me as ever
    i’lL wait for ur reply , thankss πŸ™‚

  46. inzaniachi

    thanks so much for the circuit. it has helped me so much but
    please i have an 8pin 741 ic show me how i can connect it instead of using transistors

  47. I need KIT for this particular circuit…pls reply me the details…

  48. SEETHARAMAN sir i send u email tht i want to buy this ready made circuit payment will be m\de to u please let me knw thanks

  49. ok thanks πŸ™‚
    and if u know a proper circuit diagram then do let me know ..

    thanks a lot sir πŸ™‚

  50. seetharaman

    Hi Omer SMPs for car amps are available with different voltages and current ratings. you can use them.

  51. hi sir seetharaman , i have a question to ask……..
    if i want to install an amplifier with voltage rating 18-0-18 in my car then how can i able to convert 12 volts of car battery in 18-0-18 ??

  52. seetharaman

    Hi Shubham Mosfets are best suited for high power amplifiers. IRF540 & IRF9540 are the best, freely available and inexpensive. The bias requirement per mosfet is 1.5 to 2.5 volt depends on the sample. For setting the standing current for both the output transistors you develop voltage between 2 to 6 volts between both the gates. adjust till you get a standing current of around 60 to 100mA through Mosfets.

  53. Thanks sir,
    sir please tell me, is it better to use mosfet or fet in the place of transistor in main amplifier, as mosfet can handle large current, and they dont require heat sink. They also dont have thermal runway as transistor do, when they are heated up.

    If yes then which mosfet shuld be used ,with what biasing resistance.

  54. seetharaman

    Hi Shbham Use a 100k log potentio-meter(three tags), preferred but if not available use 100k lin (not rheostat- 2 tags only). connect center of the potentiometer to C1. one end of the potentiometer to common(ground). Connect input between both the end of the potentiometer such that input signal ref is connected to common and actual signal is connected to other end of the potentiometer.

  55. Sir, can you tell where i can place volume, treble and bass controle in circuit.
    Tell me the components between which i have to use control. Plz dont tell me in the language of low pass filter and amplifier. And for these controles, may i use rheostat.
    Sir, can u tell me which transistors form filter and which amplifier.
    Very very thanks

  56. hi friends ….. does any one of u know about IC tda2052 ???
    if no then click this link to know about its efficiency and great and very easy design to built…….
    here’s the circuit of 3-way multisystem including 1 woofer and 2 speaker outputs……. can b used as a home theatre system too.. plz check out and ask me if u’ve questions about it…
    thanks πŸ™‚
    http://adf.ly/265514/circuits-master

  57. hi victor i’ve mailed you… please check it n tell me wat do u want to ask about this circuit , or any sort ov guideline…

  58. Sir where i can place volume controle in circuit, how can i give stereo input to single subwoofer as it is present in subwoofers which are commercial, as of intex etc.
    Thanks

  59. seetharaman

    Hi Rahul it should give at least some highly distorted sound of low volume with 12-0-12 volt DC. The recommended voltage is 35-0-35 you require at least +25- 0 – -25 for this circuit to function. 2N5296 is OK.

  60. hi seehtharaman sir
    My sub woofer circuit is still not working. I have made the corrections . my transistors are fine .I have tested them as well.The circuit is not responding at all.Is it because of Q4? I have used 2N 5296 instead of 2N 5294. I have tested it with a 12 0 12 2A supply.

  61. ok seetharaman sir……..
    thanks a lot….

    m gonna build this cct soon πŸ™‚

  62. seetharaman

    Hi Omer Connect it to ground(0 volt reference)

  63. ahaan….. thanks for the reply sir seetharaman…..
    i’ve read from the data sheet that i should connect these pins either to the GND or to -Vcc ……. so should i do the connection in this way ?? the IC wilL operate normalLy????

    • want? to be this circui sampl -1no plase conduct my mobil-no.9843946968

  64. ahaan….. thanks for the reply sir seetharaman…..
    i’ve read from the data sheet that i should connect theses pins either to the GND or to -Vcc ……. so should i do the sonnection in this way ?? the IC wilL operate normalLy????

  65. hi seetharaman , how u doin………. i have one question for u.. now a days i’m working with IC TDA7294 …….

    i have;nt done the connections ryt now….. but i cant understand how to deal with its standby & mute pins?????

    please can u suggest me how to deal with these pins of this IC???????

  66. thanks a lot seetharaman sir for your mail.I have got my answer.

  67. Hi seetharaman sir
    hope you remember me I have made the circuit but is not working. You told me to go to electronics hardware man .I went to him.yes you were right .Two of the transistors were connected in wrong way. i have again connected them in a proper way but still it is not working.Sir I have asked you is there a way to check the E,B &c configuration of the transistors using digital multimeter?Can you please help me with this circuit.I have even mailed you about this but could’t get your answer.

  68. ok thank seetharaman …. i’lL try….. πŸ™‚

  69. seetharaman

    Hi Omer for both the amplifiers you feed from the same power supply. plus, minus and common.

  70. ok Mr. SEETHRAMAN ……. but how will i do the connections of single supply with two amplifiers ???

    i mean should i connect in parallel or in series ??????? etc ?? with the amplifier ??

    & wat about the ground terminal ?????

  71. sir
    I went to an electronics hardware man, yes u were right. I made a mistake in connecting the E & B of the main transistors. Sir is there a way to know the EBC configuration of transistors using digital multimeter .Small transistors can be tested using that hole in the side but sir what about big transistors ??

  72. seetharaman

    Ho Omer you can use two amplifier with one supply, it should be rated for double the current of one amplifier. good quality filter capacitors are required. you can use double the value shown.

  73. please send me the circuit diagram and the components pliiiiiiiz

  74. hi mr. SEETHRAMAN…… i have a question that can i use two channels on a single power supply??????????

  75. VICTOR ,,,, yes you can ask me about this circuit….. i’ve built this

  76. can any one help me out with complete layout and components for this circuit coming to India soon wants to build for my house as gift for father

  77. HIYA MIKE PRESS MENU OR BLUE BUTTON ON THE PLAYER AND PRESS POWER BUTTON TOGATHER IT WILL REFRESH TO FACTORY SETTINGS IF NOT THERE MUST OVER LOAD OR SHORT CIRCUIT IN SPEAKER CHECK THAT

  78. Hi there, can you help me with my problem,……my AIWA NSX-K880 component is always in standby mode, it only displays a red light…
    when I press the power button nothing will happen….

    any related suggestions or any procedures to solve will do…

  79. seetharaman

    Hi Chanaka 28-0-28 @ 3amps will give you 40-0-40DC with 10000uF as filter capacitor for both positive and negative supply. which will give you > 90watts RMS into 6 ohms speaker.

  80. Hi MR. Seetharaman,
    can i use 28-0-28 3A center tap transformer for my 6ohms 100W
    sub woofer speaker? because i don’t have 35-0-35 5A transformer, and i used BD140 and BD139,instead of 2N6107 and 2N5294. but 2N3773 is same. pleas tel me these are suitable foe this amplifier. I’m from srilanka

  81. Seetharaman

    Hi Anish you can design, ensure current carrying tracks are wide enough to handle the current. ensure current carrying tracks are away from small signal tracks.
    Any chemist will be in a position to supply Ferric chloride.
    Add dilute hydro-chloric acid to give burr free edge finish. you can warm the solution little to improve speed of etching.
    Copper clad sheet available with base material phenolic, hylam or glass epoxy.
    Etched board is called printer wiring board.[should not be called as printed circuit board, as there is no circuit in it, it is just a board used for inter connecting (wiring)components, hence the name printed wiring board]

  82. Hi MR. Seetharaman,
    I dono where ask this question, my apologies if its wrong to ask here. will you answer a few questions?
    1. can i design the pcb design for this circuit using expresspcb?
    2. To etch our own pcb, where to get ferric chloride? I mean, will it be available in local shops, or it must be got in cities such as chennai?
    3. what is the name of the copper plated board used to print and etch the pcb?

    Thanks.

  83. Seetharaman

    Hi Subbu I am on it and inform you soon.

  84. Seetharaman

    Hi Victor Your box (45liters) can be of internal dimensions 50cm(W) X 36cm(H) X 25cm(D) sealed air tight enclosure with centrally, front mounted speaker. box can be of 20 or 25mm ply. joints should be sealed with white Fevicol, to make the enclosure air tight.
    Hi Manjula around 50 liters internal volume 8 to 12″ woofer of 8 ohms impedance and power handling capacity of 100Watts RMS power.

  85. dear sir ,
    what should be the cabninet size for this
    woofer size & ohms
    Dimention of the box?
    please reply
    thanks

  86. Mr Seetharaman

    Namaskar Sir mere pass Blaupankt ka Subwoofer hai 10 Inches
    for this perticular circuit muje Box Design chahiye ghar ke liye
    please help kar sakte hain ??

  87. subbu567

    Hi Seetha Raman-Have mailed you at Hotmail id-Kindly respond when convenient.Thanks

  88. edgardo rante

    i need complete disign of 100watt sub woofer amplifier with placement guide and part list.plz give me the link of full disign and diagram. thanks a lot

  89. Hengilbert

    2SC5200 can be used in these circuit too..

  90. Seetharaman

    Hi Kumar with 5amp supply your transients will be quite good.

  91. hi seetha. i put my home built 2ohm 12inch sub woofer with an adding lowpass filter.&sound is good as i thoght.but i use 3A tf.i cannot increase volume i think the problem is 3A tf.whats ur options?

  92. hi, i wanna ask u that can i use BUV20 in place of 2n3773 transistors????????

    my provider gave me these…….

  93. well done seetha im from srilanka.happy abt ur 100w ckt.keep it up!

  94. hi sir seetharaman…….. i wanna know from u dat , can i use MJ15004 or any other series of this transistor in place of output transistors … 2N3773 ????????????

  95. Bhaskara

    Dear Mr Seetharaman,

    In my marantz SR 73 AV Receiver, in one of its front Channels( Front Left ) a “pat-Chit” noise begins after 2 or 3 minutes of switching on, some times bit earlier. Initially when switched on it works very fine( there is a relay inside, which switches on the speakers after a brief delay, this may be the reason there is no such sound immediately after switching on) but this noise starts after some time. But sound/music out-put is very clear but with this noise. The sound persists even when the in-put volume is fully reduced to zero. I am compelled to use this device as just pre-amplifier with all its pre-outs connecting to my another 5.1 amplifier. Pre-outs are good and is working well.

    I am unable to locate the problem. I for once I thought out-put coupling capacitors may be leaking( no such indication inside! the cabinet) and the capacitors try to charge up swiftly thereby producing this noise.

    Please advise what is the problem with my amplifier.
    And how can I fix it.
    Kindly mail me at bhaskara.india@gmail.com

    Regards.
    Bhaskara N

  96. Seetharaman

    Hi Khetran You have to use proper heat sinks for driver and output transistors.

  97. And there wouldnt be any over heating problem right?

  98. Seetharaman

    Hi Khetran you can try BD139,BD140 or MJE340,MJE350 instead of 2N6107 and 2N5294

  99. Seetharaman

    Hi Omer MJ15003 will be the best substitute.

  100. hi seetharaman!! yar i’m using 2N3055 but its giving me hum sound..can u suggest me another alternate πŸ™ ??

  101. Hi,

    SEETHARAMAN

    I am implementing this circuit as part of my analog electronics project. Is there any replacement for 2N5294?

    And secondly reading above comments I am a bit confused now. Do I have to change any values in it? Some people are complaining that Q5, Q6 and Q7 along with some resistors are getting too hot. Do I have to change any component’s value or implement it as it is?

  102. hi seethraman, can i use 2N3055 in place of 2N3773 ???

  103. hi MISKO…. you can use 2N5303 as its alternate… i’m using this n working very well……….

  104. hi MISKO…. you can use 2N5303 as its alternate… i’m using this n working very well……….. πŸ™‚

  105. hi MISKO…. you can use 2N5303 as its alternate… i’m using this n working very well……….. πŸ™‚ good luck to..

  106. seethe did you complete that filter ckt?????????????????????????

  107. Sebin jacob

    Hi seetharaman sir,
    Do u have any good stereo to 5.1 converting circuit with delay.if u have can u please sent me.

    sebinsony@gmail.com

  108. hi seetharaman sir,
    can you tell me something about substitutes for 2N3773 because I cant find 2N3773 transistor.
    Thanks

  109. Seetharaman

    Hi Sebin it is the circuit you can use, though not exactly 5.1 still it is a good stereo to 5.1 converter, will sound great. in some converters for the rear left and right a small delay circuit is also included to improve and get theater effect.

  110. Seetharaman

    Hi Sebin this is what has been used in early days of surround sound development. Please go ahead you will enjoy with the new experience playing just good stereo music.

  111. ishan1211

    Hi friends may i have PCB diagram for this circuit, please upload it and pass me a link.

  112. sebinjacob

    hi seetharaman sir,

    I am looking for a circuit to convert stereo out to 5.1 out.I have found a circuit please see the circuit and see weather it is correct,and tell me if i need to make any change in this circuit.Also please sent me if you have any alternate better circuit.

  113. Seetharaman

    Hi Badboy I have gone through the circuit i have assembled only the power amplifier, the DC stability of out put stage is poor. i am just on the job will give a feed back soon.

  114. masoodalvi

    sir ,i want a 150 watt amplifier using igbt transistor.thanking you.

  115. seethee did you notice that ckt i sent to your mail???????
    did you try it?????
    what is its diffect????????

  116. Seetharaman

    2N5294 NPN BD139 and for 2N6197 BD PNP BD140 can be used.
    You can try using BD337 for NPN and BC327 for PNP.

  117. Hi sir,
    The circuit is very good and easy. But some Problem in this circuit. The transistor (2N5294) is not available in market. Which is the transistor who match from it.
    Please told me which is the another match transistor.

  118. Seetharaman

    Hi Burhan Mr Sebin is correct this capacitor is used for decoupling negative voltage to Q1 and Q2, hence it has to be reversed.
    Hi Sebin I recently tried TDA2050 push pull > 70 watts into 8 ohms load. The standing current is around 120mA after driving the amp for 1/2 hr with amplifier running quite warm and found that the standing current has returned back to 120mA. very stable with very low distortion. This IC is quite economical with very few external components.

  119. SEBIN JACOB

    hi BURHAN,

    The polarity of the capacitor c2 given in the digram is wrong please connect the positive of the c2 to the negative of c3 and negative to the r3 and r4 (JUST OPPOSITE OF THE POLARITY MARKED IN THE CIRCUIT THIS WILL SOLVE YOUR PROBLEM)please see that you are using capacitor rated more than 50v.

  120. SEBIN JACOB

    hi BURHAN,

    The polarity of the capacitor c2 given in the digram is wrong please connect the positive of the c2 to the negative of c3 and negative to the r3 and r4 (JUST OPPOSITE OF THE POLARITY MARKED IN THE CIRCUIT THIS WILL SOLVE YOUR PROBLEM)please see that you are using capacitor rated more than 50v

  121. hello seetharaman C2 (4.7uf 100v)is getting bold and then it is exploding after several minutes why it is happening like this DC offset voltage is getting negative voltage…..

  122. hi sir!
    I need a good 100w amplifier with high output for sub-woofer circuit diagram.
    If you have the circuit please send me my E-mail furhan_69@yahoo.com.
    Thanks.

  123. SEBIN JACOB

    HI SEETHARAMAN SIR,

    I NEED A GOOD 12V AMPLIFIER WITH GOOD OUTPUT FOR 8OHMS SUBWOOFER IN MY CAR IF YOU HAVE THE CIRCUIT PLEASE SENT ME AT sebinsony@gmail.com OR PLEASE GIVE ME THE LINK

  124. i like this site. i’m an electronics graduate..

  125. seethe plzzz send your e mail id.i sent you low pass fiter ckt i usinggg

  126. thanks a lot man ……. i will replace it tommorrow πŸ˜‰

  127. hemant Raidas

    hi,sir,
    what happen when we use +12/-12 in the replace of +35v/-35v…

  128. Seetharaman

    Hi Omer the transistor which is cool is defective it has got shorted the other one is OK. You replace the cool one. Since this circuit functioned for some time indicates the amp is ok. you require a better heat sink.

  129. hi seetharaman sir , i designed this circuit it worked very well but after some time i got fluctuating sound with hum…. and the output transistors were drastically hot… and now when ever i turn it on it gives hum sound and a lil bit input signal and my 1oo ohm 2watt resistor connecting to -35v also burned out many times… what is the problem πŸ™ and one thing more one of the output trasistor get so much hot whule the other is not so… where is the problem ?? is there any problem in output transistors? or any thing else going wrong?
    please please please please help me out… i love this circuit running accurate πŸ™

    i will be very very very thankful to you….

  130. Seetharaman

    Hi Sebin use an operational amplifier feed one signal to inverting input and the other signal to non inverting input. you get the difference between the signal (say L – R) now feed this this signal to an inverting unity gain amplifier you will get the other signal (R – L).

  131. Sebin jacob

    Hi seetharaman sir,
    how we minus left signal from right and right from left

  132. Seetharaman

    Hi Sebin L – R is Left channel Signal minus Right channel signal and R – L is Right minus Left signal. these two signals will become rear left and right signals.

  133. sebin jacob

    hi seetharaman sir

    sir i didnt understand about the L-R (left right)rear and right-left rear how we get this input from sterio input can u please explane this.

  134. sebin jacob

    hi seetharaman sir

    sir i didnt understand about the L-R (left right)rear and right-left rear how we get this input from sterio input can u please explane this.

  135. Seetharaman

    Normally Ahuja has taken care of it. has it developed recently or it is there from the beginning. you can use a timer relay through which you can connect output of the amplifier to a dummy load (resistance of suitable value and wattage) during switch on and after about 10 to 20 seconds you can change to speaker. if the problem has developed recently kindly contact Ahuja for tips.

  136. I have an ahuja 500watt amplifier when i switch on a big sound β€œpat” is coming out of speaker how can i prevent this sound

  137. Seetharaman

    Hi Sebin use a sub woofer filter for L + R signal feed it to Sub woofer amplifier keep that in front of you Left and Right signals can be used as front speaker signals.Now use L-R (Left – Right) signal for rear left speaker and R-L signal for Left Left Channel. This will give you a good surround effect with a good stereo signal. With mono signal all signals will shift to front center and rear speakers will become quite. (with mono signal L=R hence L-R will become Zero. Try and enjoy it. you will definitely like it.
    Hi Badboy if you are using the subwoofer appeared in Circuits today it should work perfectly. still if you have problem add 100 PF ceramic between inv and non-inv input of the first stage amplifier IC.

  138. seethe i make a sub filter with tl074.but when potentio meter full audio signal get cut and a hissig n burr sound genarate what to do?????? i,m going to quit

  139. sebinjacob

    HI SEETHARAMAN SIR;

    HOW CAN WE CONVERT STERIO AUDIO OUT TO 5.1 OUT. DO YOU HAVE ANY CIRCUIT.

  140. hello sebinsony, its wrong, please read mr. seetheraman reply dated september 19, 2010.

  141. SEBINSONY

    Hi Seetharaman sir,
    Sir please see the polarity of the capasitor c2 in the given circuit is it correct?

  142. Seetharaman

    Hi Jacob C5 is ceramic capacitor hence no polarity.

    February 21, 2011 at 12:21 am
    HI Lordsville I can suggest a very simple cross over which is just sufficient. Woofer through 300turns of 18SWG enameled copper wire (1mm dia wire will do)on 25mm dia plastic former wound for 40mm length. Mid range through 25uF non polar capacitor or 2nos 50uF electrolytic connected back to back and tweeter through 2.5uF non polar (here you can use a polyester or paper or 48β€³ ceiling fan run capacitor)or 2nos 5uF (4.7uF standard value) electrolytic capacitors connected back to back. I am using in my system an 8β€³ Philips 40Watts woofer, 6β€³ X 4β€³ Philips standard speaker as midrange and Philips 1β€³ Dome tweeter.

  143. Sebin jacob

    Hi Seetharaman sir,
    Sir please see the polarity of the capasitor c5 in the given circuit is it correct? sir my amplifier is now working fine.thank u so much 4 ur guidance through out my construction.sir i would like 2 make a cross over network for my speaker box which has a tweeter, speaker and a woofer can u please help me

    • Romeo Nnaemeka

      Sir, please, i need a simple but durable inverter (circuit diagram) that works on 6volts DC supply to give an output AC Of about 220volts to 230volts, with an output power of about 500watts. Please sir, I’m just a beginer in electronics that wants to be the best he can be in electronic projects. I had ever had this unerasable interest in electronics since my tender age, and i believe i can help improve the society electronically with your promising guidance and support. Thanks so much. I wish more greeze to your elbow.

  144. Seetharaman

    Hi Aris without test instruments it will be difficult. But practically you can find out by reducing the volume level to just audible level, when you are just close to the speaker. a choking type of sound indicates crossover distortion. at higher volume it will become almost normal sound.

  145. dear seetheraman,
    how do i know sir if the amplifier is having a crossover distortion?

  146. SEBINSONY

    hi seetharaman sir,

    With multimeter is it possible for me to check the standing current.How can i check it where i have to connect the red probe and black probe to find the standing current,which resistor value i have to change in order to adjust the standing current.With out input my amplifier output transistors are cool when i play songs for a long time (1 to 2 hours) transistor is getting heated up i think Q5 is getting hotter. Q7 is only producing normal temperature the heat from Q5 makes Q7 heated up.Kindly help me sir.

  147. Seetharaman

    Hi Sebinsony You may short the resistance R9 and 10 if the output transistors are cool it indicated your standing current is high. Check it should not be greater than 25 to 30mA. If it is too less then distortion will set in at low volume levels (crossover distortion)then add 10 ohms and try if it within limits leave it. if it is still less increase the value if it is high reduce the value and finalise now the heating should be ok.
    Hi Aris congratulations. with indicated transistors some consume little high current, with equivalent transistors you have to do little experimenting with R9 and 10

  148. i have completed this project and its working without any problem at all. my advice is to just follow the diagram and its components and there should not be any problem. this circuit works well.

  149. SEBINSONY

    hi seetharaman sir,

    my amplifiers output transistors 2n3773 is getting very much hot when it works for a long time i am connected it to a big heat sink and also a cooling fan is their still it is getting heated and also the metal case also getting hot due to the heat from the transistors.As u said if i put a link between r9 and r10 will it stops terribly heating or should i need to increase the value of any resistors. r12 is also getting little heated.every thing else is fine.kindly please help me sir..

  150. SEBINSONY

    hi seetharamansir,

    The q7 of my amplifier was shorted now the problem is solved.but r11 r12 r13 is getting little heated is it a problem.But when i play maximum volume the transistors q5 and q7 is getting heated so-much.what is standing current.

  151. Seetharaman

    Hi Jacob 2.2uF is 225K (2,200,000PF) 224 is 0.22uF 2.2uF any capacitor you can use non polar is preferable, if not available 2.2uF 63volt electrolytic you can use (take care of polarity). Voice will get through, that depends on the attenuation in the filter if the curve 40dB / octave you will get low volume of voice is it is 20dB it will be more etc. Fix a link between Q4 and Q6 base (shorting bias components D1 D2 R9 & R10)energise, if heating comes down you have to short R9 and 10 and try if things are ok try playing music(we are trying to reduce standing current). If they are still getting heated up, Q3 Collector emitter may be short.

  152. sebin jacob

    hello seetharaman sir

    today when i connected my amplifier the r12,r11,r13 is getting heated.
    r11 is getting very much heated and once it burned out also the transistors 2n3773.again i replaced it and when i give input all the transistors mentioned above are getting heated r11 is getting terribly heated.what happened to my amplifier i also replaced q6 also connections are all ok

  153. SEBIN JACOB

    hello seetharamansir,

    The vocal sound is not of the local radio it is of the input which i have given the vocal voice of the song which i played is heard in a very low through the sub woofer.can i connect a 2.2uf poly carbonate capacitor at the input of the filter in serious will it rectifies the problem,can you please suggest me a method.When i asked for 2.2uf polycarbonate capacitor the shop keeper gave me a polistor capacitor written on that 224k 400v Is that same as the one you suggest for the c1?

  154. Seetharaman

    Hi Jacob local radio is getting in, through connecting cables acting as antenna. all inputs should be protected with RF filter. may be 100PF capacitor can be used as RF bypassing capacitor.

  155. SEBINJACOB

    i have connected the filter and connected to my sub woofer.the problem is some vocal sounds are also heard through the sub woofer is there any solution to rectify this.

  156. SEBINJACOB

    HELLO seetharaman sir,

    MY AMPLIFIER 1.5k 2W RESISTORS IS SLIGHTLY GETTING HEATED IS IT A PROBLEM.SHOULD I NEED TO INCREASE THE WATTAGE (TO 5 WATT.
    i am also using a stereo amplifier with 2n3055 wit 12v duel power supply,is it possible to use the simple low pass filter (1k resistor with 470 pf capacitor)for this at the input,i have the doubt because this has a stereo input.

    ANY WAYS WITH YOUR HELP I COMPLETED MY AMPLIFIER AND IT IS WORKING GOOD THANK YOU SO MUCH SIR……….

  157. Seetharaman

    C2 is decoupling for R4 negative supply. use minimum 50volts capacitor. 2.2nf (2200PF) is red red red. 2.2uF will be written on the capacitor. 2.2uF is 2,200,000PF RED RED Green i don’t think you will get that color code.

  158. SEBINJACOB

    seetharaman sir,
    i am using a stereo amplifier with 2n3055 wit 12v duel power supply.is it possible to use the simple low pass filter (1k resistor with 470 pf capacitor)for this at the input,i have doubt because this has a stereo input.please see my previous post also and kindly replay me for all the doubts i have asked.because i am professionaly a business management student but i am very much interested in electronics from my childhood.

  159. SEBIN JACOB

    HI SEETHARAMANSIR,

    I COMPLETED MY AMPLIFIER AND JUST MADE IT WORK US AN AMPLIFIER (WITH OUT SUB FILTER)THE SOUND WAS EXCELLENT AND I LIKED IT VERY MUCH.I AM PLANING TO BUY A SUB-WOOFER FILTER WHICH COST ONLY 65 TO 75 RS.SIR WHAT IS THE COLOR CODE OF 2.2UF NON- ELECTROLYTIC CAPACITOR IS IT RED-RED-RED.I GAVE INPUT FROM MY MOBILE AND WHEN I PLAYED THE SONG NO HUMMING SOUND WAS THERE BUT WHEN I MUTE THE MOBILE SMALL HUMMING SOUND IS THERE ALSO I FIND THE CAPACITOR C2 (4.7UF 250V)GOT BULGED AT THE TOP,WHAT IS THE PURPOSE OF THIS CAPACITOR
    .THE HIGH VALUE RESISTORS ARE ALSO GETTING LITTLE HEATED WHEN I GAVE MAXIMUM INPUT AND WORKED FOR HALF AN HOUR,IS IT A PROBLEM.

  160. Seetharaman

    Hi Jacob you are correct. please go ahead constructing all the best.

  161. SEBIN JACOB

    HI SEETHARAMAN SIR
    we have to connect this low-pass filter (1k resistor &470pf capacitor) at the input signal right.I mean before the c1 capacitor.

  162. Seetharaman

    Hi Jacob this is to avoid stray pickup of HF and resulting in hf instability. If amplifier, filter net work, power if all are in one metal chassis then not required. if not it is better to provide it as general precautions to all power amplifier to avoid the amplifier getting over driven by high frequency from previous stage or through stray pickup, which will lead to severe distortion or instability.

  163. SEBIN JACOB

    HI SEETHARAMAN SIR

    AS YOU SAID IF I ADD A 1K RESISTOR IN SERIES TO THE INPUT AND A 470 PF CAPACITOR IN PARALLEL WILL MY AMPLIFIER GIVES MORE BASS, AS I AM USING IT AS A SUB WOOFER AMPLIFIER.IF I AM USING A SUB-WOOFER FILTER IS IT NECESSARY TO USE 1K RESISTOR AND 470PF CAPACITOR, WILL IT MAKE ANY IMPROVEMENT IN THE EFFECT.WHERE I HAVE TO CONNECT THIS SIMPLE LOW PASS FILTER BEFORE THE SUB WOOFER FILTER OR AFTER THE SUB WOOFER FILTER.

    SIR U R HELPING ME A LOT.THANK YOU SO MUCH SIR.SIR WHICH PLACE ARE YOU FROM.I AM FROM INDIA

  164. Seetharaman

    Hi David for a class room you have to concentrate on voice frequencies rather than low frequency. a full range speaker (Hi-Q) will be ideal. say 6″ X 4″ or 6″ will be ideal in a small air tight enclosure of say 4 to 8 litres internal air volume. you can use TDA2040 amp with a passive tone control appeared in our circuitstoday earlier.

  165. Seetharaman

    Hi Jacob you have to increase the capacitor to 2.2uF for sub woofer application

  166. SEBIN JACOB

    HI SEETHARAMAN SIR,

    I HAVE COMPLETED FIXING THE COMPONENTS ON THE PCB.I AM GOING TO USE THIS AS A SUB WOOFER AMPLIFIER WITH A SUB WOOFER FILTER,SHOULD I NEED TO CHANGE ANY OF THE CAPACITOR VALUES TO GET MORE EFFECT.YOU HAVE SAID IN YOUR PREVIOUS POST DATED 4TH MAY TO Increase C1 to 2.2 or 4.7uf non electrolytic capacitor to improve low frequency response to 10Hz or so, with the present value the roll of will be above 50Hz itself.

  167. I’m a teacher, and I would like to use in class room. I have a wireless microphone. I need at least 20w, with the smaller woofer size. What woofer you recommend? Where do I insert volume and treble pots? Best Regards.

  168. Seetharaman

    Hi Bad boy the positioning of the speaker in your room can affect the sound inside the room. even the phase mismatch due to distance between your ear and different speakers ( sub woofer and satellite speakers) can also give raise to this problem. Try by relocating and by adjusting the angle of your speakers can definitely improve the response in side the room.
    Hi Jacob if you are very particular you can use 3nos 1 ohm 2watts resistance in parallel. but 0.47 5 watt is good enough and it will not affect the performance.

  169. SEBIN JACOB

    hi seetharaman;
    i have got all the components in the circuit except .33ohms 5W resistor. Instead of that i got .47 5W is that enough,or is their any substitute for that kindly help me.

  170. seetaaraman i complete my sub.it have a awesome boom sound.can hear up to 150-200 meters from my home but it dosin’t have the jerking power inside my room????????? why mydear

  171. Seetharaman

    Hi Jacob sorry for the delayed reply. You have to use insulating kits for the output transistors, while fitting them on to the heat sink.(mica or plastic washer with non metallic insulating bushes – washer and transistor surfaces to be smeared with silicon conductive grease to improve the thermal conduction). If you use + & – 35 volt DC for supply and 8 ohms speaker the output will be around 75watt RMS. with + – 40volts the output will be 100Watts RMS into 8 ohms speaker. With + – 22volt supply the output will be 100 watts into 4 ohms load. To avoid humming you have to use perfect layout. use large value filter capacitors with one more diode and filter capacitor after main filter capacitor as pi filter. connect power supply zero volt reference the chassis earth at only one point, that too at the amplifier input socket. use thick short length of wire say 2.5sq mm less than 3 inches to connect the power supply to the amplifier.

  172. SEBIN JACOB

    Thank you omer
    Thank you so much
    once i complete this project i will tell you how it is for me ok bye.

  173. hi sebin jacob , yes i have designed this circuit and its working very well…. humming sound is produced when u use capacitors of less value to remove this humming sound ( if produced) use capacitors of higher values with the supply… i:e 4700 Uf’s minimum…… i m using 6800 Uf capacitors…with 25-0-25 transformer… and 3ampere diodes bridge….
    if u want a design of power supply then plz visit this link …. n do comments plz… πŸ™‚

    http://adf.ly/265514/circuits-master

  174. SEBIN JACOB

    Hi seetharaman

    I am aware about the sub-woofer filter. Kindly please read the doubts i am writing below.

    My doubt is regarding the watts. It is said that we get 100 w output, is it for 4 ohms or for 8 homes woofer. should I need to make any changes in this circuit(is this circuit correct).For the transistor 2n3773 body is the collector, so when we connect both the transistors to a heat sink the collector of both transistors 2n3773 get short through heat sink is their any problem for that. Should I need to use bigger heat sink for all the transistors, or for the Q5 and Q7 big heat sink and for the rest small heat sinks? Some amplifiers produce humming sounds is this a good amplifier which is very quite when it is at the ideal state expecting your replay and helps.

    Hi omer;
    I hope you had completed and start using this circuit. How is it? Is it a good one? Does it produce any humming sound at the ideal state? Do you made any changes in this circuit to make it works? Help me please I am interested I this circuit I need to built this after considering your opinion I am waiting for your replay.

  175. SEBIN JACOB

    Hi seetharaman

    I am aware about the sub-woofer filter. Kindly please read the doubts i am writing below.

    My doubt is regarding the watts. It is said that we get 100 w output, is it for 4 ohms or for 8 homes woofer. should I need to make any changes in this circuit(is this circuit correct).For the transistor 2n3773 body is the collector, so when we connect both the transistors to a heat sink the collector of both transistors 2n3773 get short through heat sink is their any problem for that. Should I need to use bigger heat sink for all the transistors, or for the Q5 and Q7 big heat sink and for the rest small heat sinks? Some amplifiers produce humming sounds is this a good amplifier which is very quite when it is at the ideal state expecting your replay and helps.

    Hi Umer;
    I hope you had completed and start using this circuit. How is it? Is it a good one? Does it produce any humming sound at the ideal state? Do you made any changes in this circuit to make it works? Help me please I am interested I this circuit I need to built this after considering your opinion I am waiting for your replay.

  176. Seetharaman

    Hi Sebin Mr Omer is correct, you have to use a low pass filter before feeding the signal to the amplifier.

  177. SEBIN JACOB

    hi omer

    my doubt is shoud i need to make any changes in the given circuit.Will this circuit works.My sub woofer is of 8 ohms 100w.Is some amplifiers produce humming sounds and some disterbance,what is ur opinion abt this circuit.

  178. hi SEBIN JACOB , i have experienced TDA 2030’s and also this circuit… with respect to wattage this circuit is more strong… but if u want pure woofer output from this circuit then u should use a subwoofer low pass filter before this circuit….I hope it will fulfill ur requirement..

  179. SEBIN JACOB

    I am using a simple sub woofer with ic tda2030X2 the out put is not satisfactory for me.Is this circuit good for home sub-woofers i want good bass (thumping sound) please help me.I will only start making it only after your replay.i am having a transformer of 25-0-25 will it gives +-35 when rectified,is that ok for the best working of this circuit.

  180. SEBIN JACOB

    hi Mr.SEETHARAMAN,
    I have made the PCB for this circuit i have doubt regarding the watts. It is said that we get 100 w output,is it for 4 ohms or for 8 homes woofer.should i need to make any changes in this circuit.For the transistor 2n3773 body is the collector,so when we connect both the transistors to a heat sink the collector of both transistors 2n3773 get short through heat sink is their any problem for that.should i need to use bigger heat sink for all the transistors or for the Q5 and Q7 big heat sink and for the rest small heat sinks,i am expecting your replay at the earliest.any ways you are great in electronics and you have the helping mentality also.

  181. Seetharaman

    Hi Aris for 10inch woofer say with soft textile rubber cone with free movement sealed 35 to 45 liter internal volume will be the best. If it is a tight rigid cone full range speaker, around 60 liter sealed enclosure with internal volume will be ideal. Make it front center mounting that will be the best. For 8″ woofer I am using 50 X 30 X 16 cm external with 20mm wood board carpet felt fitted on the internal surface of the enclosure. external measurement with 20mm ply board of 75 X 45 X 20 cm for 10″ and 12″. These sizes were based on Philips audio application book and suitably assembled by a carpenter for me by using Philips 8″ & Luxco 8″ woofer – bolton 10″ & Luxco 10″ and JLS 12″ full range.
    .

  182. hello everybody, hi seetharaman
    i have finished this project already together with its filter. they are both working very well. by the way sir seetheraman, what is the ideal size of the speaker enclosure? im using a 10 inches speaker. tnx.

  183. Seetharaman

    Hi KVS perfectly ok. only thing is you will get less wattage with +, – 24volt you will get around 32 watts into 8 ohms speaker and 64 watts into 4 ohms speaker. Put a link between Q4 and Q6 base the current drawn by output transistors should fall down, if other things are connected properly. If current is still high and 100 ohms are getting heated up check the transistor orientation

  184. hi seetharaman. thanks for your kind reply. but now i’m using 2x24v smps. one smps +v connected to other smps com. this connection is i’m taking as com. and taking other two end as +24v & -24v.

  185. hi seetharaman,
    thank you for answering my question.
    :)))

  186. Seetharaman

    Hi KVS earth is nothing but 0 volt reference of +35 and -35 supply. you can just go though the plus minus supply as reference
    please refer to the following power supplies appeared earlier in this column.
    Dual Power Supply using LM 320 and LM 340
    40V dual power supply

  187. hi, to everyone.
    i again reply my problem in above (February 27, 2011 at 4:31 am)
    my transistors are slightly socked. and 100 ohm,2w resistors heating up. i check my all connections are correct.
    i have one doubt, should i connect the speaker one end+input signal one end+input supply(35v) com+input smps supply(230v) earth?
    now i’m earth one not connect in my circuit others all connected. should i connect earth with com?

  188. Seetharaman

    Hi Momok Connect 100K potentiometer common (one end) to ground, slider of the potentiometer to C1 and input between ground and the other end (free end)of the potentiometer.

  189. hi omer….
    thank you for the advice…
    it did work
    its awesome…
    it sounds really good… thank you admin.
    thank you omer…

    i only have one question…of where to put my potentiometer for the volume?
    ty

  190. ah..admin..

    can you post how did you solve for the resistor values?

  191. Seetharaman

    Hi Bad Boy it should be a sealed enclosure, kindly seal the hole. make the cabinet air tight by using adhesive sealant on all joints.

  192. hai seetharaman i just built the box with te size 50*40*25 but i made a mistake i make an air hole of dia 4” .is it cause any problumee????????????????
    still the output is awesome.if any change is occur wether i seal that air hole??? anser meeee yaar

  193. hi MOMOK… no the thikness does’nt matter . your connections must b complete and accurate…. yes all the grounds should b commonly connected. . . . . just u can measure the current across all the transistors to know that if they r working or not??
    and also u can check by touching them if they r heating up then they r working………

    at the end , make sure that all ur connections are accurate…

  194. hi omer.
    we have done the circuit. using BD140 and BD139 as substitute, as it was suggested on the previous post..

    but we have encoutered some problems

    -the output voltage on the output of the amplifier reach 17V…what do you think the problem was???
    -should all the grounds be connected as common one???
    -we have design the layout on pcb wizard on a 4 by 6 inch board will the thickness and distance of the connection from each other will give big affect?
    -how will we know if transistor is working?

  195. ho MOMOK…….. btw ur english is good dnt underestimate ur self man πŸ˜›

    n ur alternatives are as…..

    2N3773 = 2N5303
    2N5294 = D313
    2N6107 = B857
    BC108 = BC109

    i hope u will find ……..

  196. hello, thank you for this design, but just got problem looking for
    bc108
    2n6107
    and 2n5294

    is there any alternative replacement could you recommend to me,thank you,

    sorry for my bad english

  197. thanks OMER for your kind reply.
    i’ll go to check that and again reply to you are.

  198. hi, KVS i think u r facing the connection problems…..
    plz check ur (( BCE )) connections of all ur transistors….

    i think u have wrongly connected ur (( B C E )) connections……..

  199. hi. have a good day to all.

    i have build this circuit.
    but it’s not working.
    100ohm,2w resistors are heating and the transistors are slightly socked when it touch.
    i can’t get where is the problem and what is the remedy.
    anyone knows to rectify this problem please explain me.

  200. hi seetheraman ……. i have successfully designed this circuit …… i m using 20-025 power supply with 6800Uf capacitors with 3 amp diodes bridge …

    the amplifier is connected directly to my pc… the sound is good but there is lil bit hum sound which sometyms become loud…. i dnt know where is the problem and only one transistor is heating up others remain cool… where is the problem ???
    plz guide me setheraman i will wait for ur kind reply… thnkew πŸ™‚

  201. Seetharaman

    Hi Gopi the gain of the amplifier is around 70. To get 100Watt RMS your input should be 30 / 70 = 400mV RMS. To achieve you may to add one pre amplifier stage with a gain of 10 it should take care of your problem.

  202. Seetharaman

    Hi Bad boy for a 12″ woofer an internal volume of 40 to 60 liters will be ideal. Center front mounted sealed enclosure of 50cm hight 40cm width and 20 to 25cm depth will be most suited. The wood thickness should be 20mm and inside walls should be covered with carpet felt or glass wool to avoid coloration of sound.

  203. hai guyzzzzzzzzzz im successfully comlplete my amp .and buy a 12” subwoofer …if any one have the sub bod size please uploadd