Readers are advised to proceed with the construction of the presented circuits only after understanding the concepts from the core. Not adhering to this can lead to failures and frustrations.

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Saturday, January 7, 2012

How to Make a Hi-Fi 100 Watt Amplifier Circuit Using 2N3055 Transistors

The amplifier circuit explained here was built and tested by me and am extremely pleased by its performance and also ruggedness as far as maintenance and handling is concerned. Basically, the entire configuration is a symmetrical class A amplifier incorporating an input filter stage, an intermediate driver stage and a powerful symmetrical output stage consisting of the versatile 2N3055 power transistors. The circuit efficiently drives a 100 watt 4 Ohms speaker with inputs derived from any audio source like a cell phone or DVD player etc.
Before you learn how to build this interesting and useful 100 watt amplifier circuit using 2N3055 transistors, a prior understanding of the involved circuit configuration would be very handy, let’s begin the explanation with the following points:

Circuit Description

A quick glance at the given circuit diagram makes us conclude that the output configuration is not symmetrical, since the transistors T15 and T16 are both NPN types.

The input stage of the circuit begins or initiates with a symmetrical differential preamplifier stage consisting of the transistors T1, T2 and T3, T4.

T5 and T6 are positioned as the current sources which are further extended as the driver stage consisting of the transistors T7 and T8.

However a closer inspection tells us that of course the wiring is symmetrical, having the transistors T11, T13, T15 at the upper section acting like special booster transistor package.

Similarly the lower section also employs identical super booster stage consisting of the transistors T12, T14 and T16.

The above two sections are perfectly complementary to each other, with reference to the diagram which indicates their emitters being terminated to a common point through the resistors R25 to R27 and via R28 to R30, this effectively that the wiring is exclusively symmetrical by nature.

The output stage is able to produce a massive 200,000 times amplification factor with comparatively very low quiescent current drain.

The quiescent can be set by the adjusting the preset P1.

Due to a non critical nature of the circuit, the entire project can be easily built over a general purpose PCB, however the layout of the components or rather the placement and the ratio of the distance of the components must be kept as identical as possible to the layout of the circuit diagram.

Though a common heatsink may be used for the entire set of the output devices, I personally used separate individual heatsinks for each of the transistors. This saved me from the headache of using the cumbersome and low efficient mica isolation kit between the transistors.

The inductor is kept for improving the dynamic nature of the circuit. It is built by winding 20 turns of super enameled copper wire over the 1 Ohms resistor itself. The wire is selected to be close to 1mm in thickness.

Though not absolutely necessary, for better thermal stability the transistors T9 and T11 and also T10 and T12 should be glued together, preferably by attaching the respective pairs face to face.

The quiescent current should be ideally set to 50 mA through the following initial procedure:
Short the speaker terminals,

Connect a DMM set at current range in series with the positive of the power supply to the circuit,

Next adjust the preset such that the meter reads an input of 50mA, that’s all, the amplifier’s quiescent current is set and now the connections may be restored for the normal operations of the system.

The power supply circuit is also shown along side and as can be seen there’s nothing special about it and may be built using the shown ordinary sets of components.




Parts List of 100 watt amplifier circuit


R1 = 430 K,
R2 = 47K,
R3 = 330 Ohms,
R4, R5 = 12 K ,
R6, R7, R20, R21, R22, R23, R24 = 1 Ohm, 3 Watt, Wire Wound Type
R8, R17 = 68 Ohms,
R9 = 100 K,
R10, R11, R12, R13 = 5K6,
R14, R15 = 12 K,
R16, R19 = 100 Ohms,
R25 = 10 Ohms / 2 Watts,
P1 = 100 Ohms Preset, Linear
C1 = 1 µF / 25V,
C2 = 1 n, CERAMIC,
C3, C4 = 100Pf
C5 = 100 n,
C6, C7 = 1000 uF / 35 V,
L1 = 20 turns of enameled 1mm copper wire over R24,
D1, D2 = RED LED 5mm,
All other diodes are = 1N4148,
T1 = Matching BC546 pair,
T2 = Matching BC556 pair,
T3 = BC 557B,
T4, T7, T8 = BC 547B,
T5, T12 = BC 556B,
T6, T9 = BC 546B,
T10 = BD 140  
T13 = BD 139  
T11, T14 = 2N 3055  
General Purpose PCB,
All the transistors T10, T13, T11 and T14 ae mounted on suitable heatsinks



The original design, (courtesy - elektor electronics)






94 comments:

  1. I know this circuit. Its crescendo... the best ever i had in my life. Mine is working fine...12 years now. no error at all. The driver BD139/140 can be replaced by C2073 and A940.

    ReplyDelete
  2. PLZ TELL THE SPEAKER RATINGS LIKE 8 OHMS/1WATT OR SOMTHING LIKE THAT PLEAASE ITS URGENT

    ReplyDelete
    Replies
    1. Speaker must be rated at 4 Ohms/100 watt RMS

      Delete
    2. This circuit gives 45W into 8 ohms and 65W into 4 ohms. The sound quality is superb.

      Delete
  3. Also please can you show me how to connect the transistor on the PCB. please help i am new to this transistor.. i have a to-3 package which has only 2 legs. the base and the emitter...furthe the collector part is the rest of the metal body.. plz help

    ReplyDelete
    Replies
    1. Please refer to the 2N3055 datasheet for knowing the pin details.

      By the way they must be mounted on heatsinks, not on PCB directly.

      Delete
  4. thanks for sharing this interesting looking cirucit. I look forward to maybe trying this out with some 2n3055s. By the way the power supply schematic shows a "dual" or center tap output. But your circuit shcematic has just 25V -GND. What is the correct voltage ... +25 GND -25 or +25 - GND ?

    ReplyDelete
    Replies
    1. You are welcome.....one of the terminals of R1,R2,C2,C6,C7 are connected to ground point, or the (0) point of the power supply.

      Delete
  5. supply. 32-0-32 5A. that is the best, T10 T11 T13 and T13 are directely exposed to 5A. The rest of the circuit, supply can be given through two diodes IN 4007. It will deliver only 1A max. That good for small transistors so as to keep distortion minimum as possible. U can give voltage from 27-0-27 to 34-0-34 max.

    ReplyDelete
  6. In actual crescendo circuit, The instead of LED D1, there is 5.6V zener and 47uf capacitor connected in parallel. Same as in the other side D2 also. Why there is a LED here ? Is it for thermal stability ?

    ReplyDelete
    Replies
    1. LED is used for eliminating noise which is normally a problem with the zeners.

      Delete
  7. TDA1557Q is mosfet amplified duel amplifier 100 + 100 Watt IC... :)

    ReplyDelete
    Replies
    1. :-O :-) :-D Thanks very much.....

      Delete
    2. Fine, every one is running after the amplifier power output rather than the quality of sound. The sound produced from these types of crescendo circuit is better than you hear from theater.

      Delete
  8. @ power supply circuit.... what should be the rating of the transformer? And what type those diodes connected in full bridge in the power supply circuit?

    ReplyDelete
    Replies
    1. The details are provided in the diagram.

      Diodes can be 1N5408s

      Delete
    2. I have a few questions and I hope someone can help me with these. I am building this circuit and in the Circuit Description Column it mentions the R25 to R27 and via R28 to R30. I see R25 but not R26 to R30 or am I missing something?
      The resistor between T8 and T7, what number resistor is it and the value?
      Then I see R18 in the drawing but not on the parts list, what is the value to R18.

      I appreciate the help,
      Thank,
      Tony

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    3. please check out the updated (original) circuit in the article

      Delete
    4. Thank you Swagatam. Now with the original do I use the components values from that or do I have to redo the whole circuit to the original schematic.
      And thank you for your quick response.

      Delete
    5. I think there's hardly any difference between the diagrams, you may continue with the previous components.

      Delete
  9. Thats it ... thats the crescendo baby. This circuit was famous in 90s. I still have the picture of printed PCB softcopy with me. This PCB was last produced by HITECH company, now they stopped producing electronics goods. Thats made the end of this PCB board. No one can reprint the board without permission. Then people are forced to relay on other circuits. The beauty is, this is a marvelous design and can handle low frequency (low bass) without any problem. Almost no other modern circuits can beat the flat frequency response delivered by this amplifier. The only thing is You should give 28-32V dual supply, 4A-5A current for superb low bass effect.
    The very first crescendo circuit is published in elektor magazine on December 1982 :-)

    ReplyDelete
  10. Hi, everybody. yes, it is a great amplifier. I tried it on a veroboard but hum is too much. anonymous says he has the PCB soft copy. will you pls email it to nkanil.klm@gmail.com?
    Anilkumar

    ReplyDelete
    Replies
    1. I have posted the circuit dude.
      Lancy Felix.

      Delete
    2. Hi sir, can you send PCB soft copy to my mail:- k.amit2000@gmail.com

      Delete
  11. Sir,
    I want to made this audio amplifier circuit. But in the amplifier circuit you show the 25V supply and in power supply circuit there is 30V.
    What is co-relation between them. secondly, I want to known the rating of center tap transformer you have used.

    Sudesh

    ReplyDelete
    Replies
    1. After rectification the voltage may rise upto 30V, but it won't be a problem because the amplifier can handle upto 40V

      Delete
  12. Hi Anonymous can u please sent me the pcb soft copy of the amplifier. My mail id patnaik2surya@gmail.com. thanks in advance.

    ReplyDelete
    Replies
    1. can you send PCB soft copy to my mail:- manujamicro1@gmail.com

      Delete
  13. I had posted the amp PCB diagram ( with both sides) dude. Use photoshop, make more darker circuit and print in on copper clad glass epoxy board :-)
    Anyway this amplifier got a special powers supply board with an input 27-0-27 and 18-0-18 AC and the output is 27-0-27, 18-0-18, +-24 and +-12v DC supply (This is for tape deck, transistor pre-amp, tone control etc.. I have the same amp + powersupply board on my old deck and powersupply board contains transistors like BD139, BD140 etc.. i dont want to reverse engineerer that stuff.... The above power supply circuit is ok for the main amplifier as told by 'Swagatam Majumdar' but actually 4700ufx4Nos capacitor is there in actual board....
    Finally my name is Lancy Felix :-)

    ReplyDelete
    Replies
    1. Thanks for the help Lancy, keep it up mate:)

      Delete
  14. Hi Lancy, will you please send me those PCB designs? My email is
    wedt400@gmail.com .Thank you.

    ReplyDelete
  15. do you have any sub woofer pre amplifier circuit for this power amp if you have mean's wiil you please send me (kanagarajbe114@gmail.com)

    ReplyDelete
    Replies
    1. You can use the following circuit, just add a low pass filter at the input of the amp:

      http://homemadecircuitsandschematics.blogspot.in/2012/04/how-to-make-simplest-100-watt-mosfet.html

      Delete
    2. Thank you sir,and i want single supply transistor power amplifier circuit I have o-24 transformer 5amps

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    3. I am sorry kanagaraj, I do not have any such circuit presently in my blog, I will try to update it if possible soon.

      Delete
  16. sir hoe to increase left right bass depth without using tone controles (only using pre amplifier) if you have any circuit like that give me

    ReplyDelete
    Replies
    1. You can replace the preamplifier with this circuit, it will work as both preamp and low pass filter:

      http://homemadecircuitsandschematics.blogspot.in/2013/06/make-this-low-pass-filter-circuit-for.html

      Delete
  17. sir i want one automatic battery charging circuit (12v) i want that circuit automatically sence low battery and start charging and cut the charging when the battery is full

    ReplyDelete
  18. Hi Kanagaraj, You can make this circuit:

    http://homemadecircuitsandschematics.blogspot.in/2012/02/how-to-build-automatic-6-volt-12-volt.html

    replace the feedback 1K resistor with 100k pot and remove the series 1N4148 diode.

    ReplyDelete
  19. sir hoe to cut below 80HZ in low pass filter circuit

    ReplyDelete
  20. sir i want buffercircuit & bass boost circuit using op amp

    ReplyDelete
  21. what is the different between digital ground and analog ground and how to joint these two grounds

    ReplyDelete
    Replies
    1. it's a big explanation, cannot provide it here....these grounds are intended for providing discrete paths for analogue and digital signals, they should not be joined.

      Delete
  22. Hi everyone!
    Would somebody send me a PCB design of Crescendo Amp from the shematic up there..Will be very grateful :-)
    My email; linjo456@gmail.com
    Thank you !

    ReplyDelete
  23. Sir,
    I have built this circuit and its working nice . Thanx for the circuit .
    I am connecting this amp to woofer and tweeter so how I should connect them by creating passive crossover . What values of capacitor and inductor should be used ?? What kind of Inductor to be used ??

    ReplyDelete
    Replies
    1. Don't use passive filters, use active filters as it will enhance the effects rather than deteriorating.

      You can use the circuit IC2A/B section of the circuit shown in this link, use it in between your amp and music input:

      http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-your-own-active.html

      Delete
  24. Sorry for the delay yar. I have forwarded the PCB diagrams . Anyway am using passive filter only for the above amplifier. Mine is BOLTON, model no 305 BN2. Its some what old but very simple construction and awesome filter. Its good choice to wind coils rather than buying. The modern multiple coil crossover is worth useless. Just open any old 10" or 12" audio box, (70's to 90's is good... Old is Gold) measure the coil gauge, ID, OD, and height of that wound core, no:of coil in a single layer. Perimeter =Pi*D. You could easily calculate the total coil length. The only important thing is coil thickness.. the more the better. You could recalculate with simple equation also.
    Otherwise measure with wire gauge, measure the inductance... done :-)
    Lancy Felix.

    ReplyDelete
    Replies
    1. That's great support Lancy, Thanks very much.

      Delete
  25. Hi Anonymous, could you please send me the PCB layout for this "Crescendo" amplifier. My email is agungprie2010@gmail.com.
    THank you in advance..

    ReplyDelete
  26. hi Anonymous,could you please send me one regulated power supply circuit with output short circuit protection(12V/3A)

    ReplyDelete
  27. Would it be okay if i use all the smd component instead of through hole component ,can my circuit behave diffrently under smd components ????

    Please answer ......

    ReplyDelete
    Replies
    1. yes you can use SMD, the circuit will work perfectly with them too, no issues.

      Delete
  28. there are 2 types of 3055 transistor. first one is 2N3055 and other one is TIP3055. TIP3055 is a big transistor. 2N3055 is like a normal transistor. which one is good for this amplifier. I cant understand the L1 . How can i make it in home. I'm stuck in this plese reply me soon.

    ReplyDelete
    Replies
    1. Both the transistor types are almost identical with their specifications, only the package is different.

      You can use any of these as per your convenience....I have updated L1 data in the parts list.

      Delete
  29. can you post a completed circuit with all parts

    ReplyDelete
  30. please some one send me the PCB soft copy. my email- manujamicro1@gmail.com

    ReplyDelete
  31. The value of L1 has been updated in the parts list.

    ReplyDelete
  32. http://i00.i.aliimg.com/photo/v0/309836240/TIP3055_Power_NPN_Transistors_ST.jpg

    http://img.bhs4.com/fa/d/fadf150f65b8acbacfb586f7ab802d0a80dced83_large.jpg

    checkout this links and tell me the witch transistor is good for this circuit. please some one send me the PCB soft copy. upload that and give me the download link.

    ReplyDelete
    Replies
    1. as mentioned in my previous comment, both the transistors are good and rated almost equally, it depends which one you prefer as per your convenience.

      Delete
    2. http://i00.i.aliimg.com/photo/v0/309836240/TIP3055_Power_NPN_Transistors_ST.jpg

      then can I use this transister

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    3. yes you can use them, be sure to add large finned heatsinks to them

      Delete
  33. is there a good quality bass in this amplifire.

    ReplyDelete
    Replies
    1. No, it does not include bass control, you will have to add it externally

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    2. no no I mean the sound. can i get a good bass sound from this

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    3. you can get god bass only after including a bass/treble circuit at the above amplifier input

      Delete
  34. do you have is there any subwoofer circuit schematic. if you have please send me. Because i want a good bass. thats what i like

    ReplyDelete
    Replies
    1. I'll try to include it soon in this blog and give you the link....

      Delete
  35. in our city there was a young man. he makes subwoofers in home and sell them. but i dont have money to buy that. he has many types of subwoofers. like 5.1 , 2.1 , 7.1. now he is not here. but i want to make one. quality bass sound subwoofer circuit diagram. thats what i need. if you have that send me. i will give my email. thankz

    ReplyDelete
    Replies
    1. presently i do not have it, i'll try to post in soon and let you know.

      Delete
    2. ow do you have above amplifire pcb diagrame?

      Delete
    3. sorry, presently the pcb design is not there with me...

      Delete
    4. I have seen your link, yes you can use it with the above circuit

      Delete
    5. ...and please do not include external links, i'll just keep deleting them.

      Delete
  36. how can i contact you for a personal matter immediatly pleaseeeeeeeeeeee

    ReplyDelete
  37. This looks like a very nice amplifier, thanks for the detailed schematic and items list! I have just ordered the components and I'm excited to get started!

    I have one questin though - I can't seem to figure out the recommended power suppy voltage/current. I'm confused with the shchematic sayin "Tr1, 2 x 25" Do I need a dual transformer, or?

    If I only need one, will 30 Volts at 5 Ampere be suficient? Can less do it?
    Im planning on winding my own transformer, so no need for "standard values" :)

    ReplyDelete
    Replies
    1. Thank you!
      The transformer needs to be a center tap transformer, that is with two sets of winding on the secondary, rated as 24-0-24V at 2amps or more.
      you can use a transformer rated at 30-0-30V/2amps also.

      Delete
    2. Thank you very much. If I want to make 2 of these amplifiers, one for each channel, can i just make two identical amps and ground them to the same "0" on the transformer (offcourse with twice the current), or do I need 2 seperate center-tapped windings with their own respective "ground/0"

      Delete
    3. separate power supplies won't be required, you can use the same supply, just by making the grounds common...

      Delete
    4. (+) ans (-) supply lines will also need to be joined as common rails for both the units....

      Delete
  38. So, ff I measure between;
    + & 0 = 25V
    - & 0 = 25V
    + & - = 50V

    Correct? :)

    ReplyDelete
  39. Hi guys, could you please send me the PCB layout for this "Crescendo" amplifier. My email is ttararo@gmail.com.
    THank you in advance..

    ReplyDelete
  40. hi Lancy Felix

    is it possible for you to send me a pcb layout for this amplifier?
    my email address is ttararo@gmail.com

    much appreciated.

    ReplyDelete
  41. Hi again

    I have built the amplifier, and i am getting an amplified signal out of the speaker, but it is very quiet, and a bit distorted. I tested the voltage over all the tranistors, and its at approximately 35 volts, except the T7+T8 - they are only showing between 0,1 - 1V. What could I be doing wrong?

    ReplyDelete
    Replies
    1. No, there's definitely something hugely wrong with your connections or the parts.

      Once built and set the output should provide a large amplification, even without any input music you should be able to hear a big Hiss on the speaker.

      did you adjust the quiescent current as suggested in the article??

      Delete
  42. I adjusted the P1 with an multimeter in series with (+) to the power supply, but no matter how much I djusted the 100Ohms preset, it only showed around 3-5mA

    ReplyDelete
    Replies
    1. there's something not correct in your circuit, check all the connections many times you should be able to locate the fault...I built this circuit some 10 years ago and succeeded at the first attempt.

      Delete
  43. sir i need regulator power supply for luxion 1watt led i want to connect 8 led's input voltage 24v

    ReplyDelete
    Replies
    1. use the following circuit

      http://homemadecircuitsandschematics.blogspot.in/2013/06/universal-high-watt-led-current-limiter.html

      Delete

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