Correcting hum, buzz or distortion in audio amplifier projects

[@kyle8952]

That trick with putting a 1K resistor across the input is gold. Solved all my problems

[@shyamprasad674]

YEAH HE IS RIGHT🤩🤩 I am very Happy Now🎉🎉

[@scottk7679]

Fantastic practical pointers. This video has addressed several issues that I have had building small amplifiers. Thank you for sharing your knowledge!

[@JohnAudioTech]

+Scott K Glad it has helped you out. In my early days, I was stumped as to why amplifier circuits I built were not behaving properly even though I was sure I had the components all correct. It turned out to be these little "gotchas" that foiled my efforts.

[@jstro-hobbytech]

@@JohnAudioTech i've been an ass to you in the past john. i have mental illness which makes me act erratically from time to time. i've spent like 2 months in a place for people with ptsd and i'm apologizing to everyone i was a dick to. from the bottom of my heart john i'm very sorry. i've learned alot from your videos. i know you love leds and i happen to have a massive collection of every kind you can imagine. would you happen to have a po box and i can send you a kit of goodies to play with. along with some surprises perhaps. ask eddie over at kiss analog, he can attest that i'm telling the truth and i honestly feel horrible for being a jackass. name is joey from cape breton. he'll know who you speak of. id understand if you didnt accept my apology.

[@AUDIOFOX33]

SO clear info no blabala just answers!End of video is deadly !Thank you man!

[@vishalj27]

Exactly what I am looking for the past few weeks. I didn't find that much perfect and easy solution anywhere else. I have these issues with TDA2030 and now I know Nice Job 👌

[@sutharpiyush71]

How you done it bro? 🤔

[@vishalj27]

@@sutharpiyush71 This may help, www.instructables.com/id/DIY-21-Class-AB-Hi-Fi-Audio-Amplifier-Under-5/

[@sutharpiyush71]

@@vishalj27 I'm already using an amplifier. A home theatre system 4.1. Can I use a Resistor between RCA Input? Do you think that can help to reduce humming sound?

[@vishalj27]

@@sutharpiyush71 That can be a problem of ground loops. I made an amplifier by myself and these tips work for me.

[@sutharpiyush71]

@@vishalj27 The tips on video?

[@chance1986]

Thanks for this useful explanation. I like how you addressed the different sources of noise and provided separate solutions for each. I learned a lot.

[@tallnrough68]

Just wanted to tell you this helped me solve an interference issue I was having with my headphone amplifier.... I was getting strange buzzing at random times , kind of like in your video. I put resistors across the input terminals and almost all of the issues went away.... thank you very much !

[@JohnAudioTech]

Thanks for the feedback! Good to hear when my video is helpful.

[@tallnrough68]

JohnAudioTech as a token of my gratitude I would like to send one of my amps to you to take a look at and keep. If you accept, please let me know where to send it to

[@tallnrough68]

not sure if you got my last message ? did you ? about my headphone amp ? also, it would be cool if you did a video on potting liquid or potting epoxy, if you have not already

[@rich1051414]

If you don't fully encase the amplifier you can get really weird and illogical hum coming though. One of my circuits hummed when people walked by, and I racked my brain figuring out why, when the issue turned out to be an acrylic window I had on the chassis to allow the internals to be visible. I solved the issue with some copper mesh(I ripped apart a copper scrub pad and used it as a emi screen under the acrylic).

[@jarret9438]

You could have filtered all that out instead.

[@CaribbeanGTR]

I enjoy your Tech Videos. This is better than going to University to go learn the same stuff. I have basic electronics knowledge so I can follow all the things you're talking about, and from previous videos I now understand the difference between the various Class A, B, AB, D; what's push-pull and why they are called that too. Need to acquire some scopes now.

[@varunkavil3154]

start grounding did helped a out, thank you sir

[@anti_globalista]

Usually people don't have this issues You produced by reducing DC (PSU) filtering. But a lot of them have grounding issues (me included, with diy preamp). I think proper grounding is THE topic to be discussed and explained with some real life examples. And I have seen Your excellent video "STOP hum and buzz in your amplifier projects !"

[@dealio82]

Next do a video on choosing the right filter cap :D

[@anindyamitra5091]

Sir, I kindly request you to make a video about, "humming" problems in a preamp board to power-amp board connection, where both of the boards individually doesn't produce any noise themselves when connected independently. The boards being placed in a metal chassis with common power supply.

[@ot4kon]

Probably a ground loop. Isolate the pre with an isolated DC to DC converter.

[@adammorris5253]

Great video! Could you do a video on choosing the amplifier chip? What to look for on the data sheet, or any more practical advice would be greatly appreciated.

[@JohnAudioTech]

Adam Morris That is a very good suggestion. Added to my list of future videos.

[@gamingcndorito]

My amplifier looking like the first example 😁😁. What I notice also is that most of the noise will go out when is solder. I have a lot of problems and noises because the protoboard is only making contact with wires but not tied down (soldering) but finally I made one and the only problem is the noise when you touch the input cable which now I can fix it by adding a 1k resistor as you pointed. Thanks

[@MatthewPeoples-ll2mg]

Great job nice work. Thanks for sharing your experience 😊

[@joohop]

your a good teacher my friend , have you thought about building bigger say 100 watts ATB

[@ADRIANNORMANNINA]

Great video!, I have had these same problems with the TDA2050, now I know

[@celtichongy]

Excellent suggestions John, thank you for sharing.

[@cornevanzyl5880]

interesting... in electrical engineering in circuit analysis, we learn that it doesn't make a difference because its connected to the same node= same voltage. thanks I'll keep these things in mind for future projects

[@researchandbuild1751]

That shows you the difference between theory and practice, dude. Real wires have resistance and inductance. Star grounds must be used

[@CaribbeanGTR]

Do you know the ILP Electronics complete Hybrid Amp that require no external components apart from the Power Supply, rectifiers and Filters? The specs are mind blowing. Would love to see how the test out on a bench with the scopes. Incredible freq response from 10 Hz - 1000 Khz in some cases and 0.01 THD on the mosfets. Output from 30 - 180 WRMS. Low cost.

[@SuperSupplyGuy]

I remember a good sentence from Radiofun232. He said in a good quality Amp everything has to be Connected. Every knob and especially the metal Case. I'm experementing with a Mix of analog and digital circuits and noise is a big issue. Digital noise is horrible. The best way around are Star shaped gnd Lanes as you explained it in this vid. Is that the right term? "Star shaped lanes" don't know but you get what I mean. This can't be said to often. Good Video :)

[@mohitgoel6739]

Hi John, My amplifier TPA3111 is producing pop noise everytime on enabling it. I have enquired form TI forum about it but didnt get any help. Do you know the solution to get rid off pop noise?

[@dhaka88o28]

Thank you sir. Very good video. Waiting for the next

[@jorgevbass2776]

Hi thanks for sharing this info! I'm making a bass amp (only power amp stage, because i a have a external bass preamp) but when i connect the bass preamp to amp (hi z output) i have a lot of hum noise but when i try to connect another source (for example the laptop output jack) the sound its clean (its a mono amplifier using the same connection and wire used to connect the bass preamp) what could it be?

[@rogert151]

I'm trying to modify a used computer subwoofer into a Bluetooth speaker using some junk parts I have lying around, this helps, Thanks for the good info, what are some common audio signal voltage levels, for example on headphone output ?

[@amitghosh6966]

Please do a video on What is Ground loops in audio amplifier circuits and how to remove them. Searching on Google for this gives confusing answers

[@amitghosh6966]

Again I have some questions- 1. If the Signal and Ground wires are twisted, does it reduces humming and Noise instead of using shielded cable for input ? 2. You have used Plastic boxes as cabinets for your amplifiers in some videos. But if a metal cabinet is used, will it result in humming (the transformer and amplifier circuit being the same cabinet) ? If so, how to reduce humming in that case ? 3. Can a potentiometer be the reason for increase in hum or noise in an amplifier circuit due to impedance mismatch ?

[@JohnAudioTech]

1. Yes. twisted pair can reduce noise picked up on the wires. Shielded leads are a better option if needed. 2. Metal is better at shielding but you should avoid ground loops caused by the metal casing if the input, power and output grounds are connecting to it. 3. Possibly. You should use the minimum potentiometer resistance that will work for your circuit.

[@easygeorge3161]

@Sound Speeds 2.5mm to 3.5mm adapter connected to headset of phone , then to 3.5mm to 1/4 phono (,mono) then inserted to mixer using aux send and mic input,, ,, dial does not hum but when you try to dial a number, a loud humming comes up,,, how do I fix this ?

[@HillOrStream]

Great video, lined up all the usual suspects for prosecution!

[@NissanInfinitiGuru]

I have a 2002 Tahoe and I'm getting really bad ground loop humming to the rear speakers. Based on my research I discovered it's bad rear radio unit which fixes the issue temporarily if replaced until it goes bad again. My big question is, can I add something right on the speaker to isolate the humming noise without replacing rear radio unit?

[@bukenyachristopher4308]

You're the best bro,thanks

[@brucermarino]

Excellent as usual! Thank you!

[@DanubioRodriguez]

what capacitor can be used in my tda7377 i listen noise from fan atx need add a cap, noise in high freq

[@waynewayne3709]

If your using dual rail volt ie plus and minus 18 volts or more then this type of amp chip does not need coupling cap to the speaker.. How ever using just 1 supply say 18volt..zero. Then use 3300uf to the speaker at the chip out put. Also look at the date chip in of rhe chip you have..

[@stealth418]

This is likely how dubstep was discovered...

[@Rainbow__cookie]

Lol

[@SineEyed]

Do you have a video where this star ground or whatever is used in a working circuit and clearly identifiable? I've heard you mention it in a few videos but it isn't self evident on your breadbaord..

[@amitghosh6966]

I have two questions here- 1. I have an audio amplifier board based on LA4440 ic and I powered it using a 12 Volts 3 Ampere transformer and used twisted wires at inputs and outputs along with a 47 K stereo potentiometer for volume control. I used 5 Inches speakers. The problem is that the amplifier makes loud humming all the time even without any input signal and turning up and down the volume potentiometer makes no difference in humming sound. What should be done to reduce humming ? 2. Secondly, if I connect a usb mp3 module with Bluetooth function to the amplifier board using the same transformer after connecting a 5 Volts regulator, there is also a constant beep sound along with the humming sound but when the module is disconnected the beep sound stops but the humming sound remains. What should be done to reduce both the Humming sound and the Beep sound ?

[@JohnAudioTech]

It could be a mains frequency hum. Be sure you have a good sized filter capacitor in use. A 4,700uf 25 volt capacitor is a good start. It also sounds like a grounding issue. Google star grounding for more information.

[@amitghosh6966]

@@JohnAudioTech I have a 4700 uF supply capacitor. My amplifier board has 4.7uF input caps and a 47K stereo potentiometer connected before it and I connected an usb mp3 module to the amplifier via the potentiometer but since that was producing a constant loud beeping noise I disconnected the module and tried using the amplifier with my mobile phone to play music but even then the amplifier is making Humming sound all the time, even when nothing is connected to the amplifier. Turning up and down the volume when nothing is connected makes no difference in humming sound. I request you to please publish a video on how to connect an audio amplifier circuit to an USB mp3 module (the one that is used to play music from flash drives and memory cards and also via Bluetooth) so as to have very lower noise and humming.

[@anindyamitra5091]

An amplifier that I made (using transistor push-pull), works fine (no hum or buzz, no unwanted feedback) but when I plug in any other appliances (specially reactive load) on the same 220V A.C. line, there is a loud "click" sound (very annoying), it also occurs when the amplifier's power supply transformer is plugged out(not while plugging in) of the mains. I had an amplifier that had STK4141 chip used in it (without any preamp or tone control circuit), which didn't have that issue. Can you explain, why this is happening? And how to attenuate it?

[@JohnAudioTech]

The amplifier is picking up the noise on its input. Be sure the input is well shielded. You may need to filter the AC power input. The most basic filter is an AC mains rated safety capacitor.

[@anindyamitra5091]

Exactly, I got your point, I had checked everything except the input, now it is fixed, thank you very much. I had tried filtering the AC mains using a 0.33uF 400V x2 capacitor, parallel to the transformer's 230V AC side, but that didn't work, though, checking the input did reduce most of the noise, thanks again, for mentioning the input fix.

[@orojasp]

Thanks a lot for sharing this!!!

[@zardozica]

Hi John, learned a lot from this. Have a question for you. I just started making my own guitar pick ups and some, but not all generate a loud hum when put into an amp. When I touch either the pick up or the metal parts of the cable, the hum goes away. Am I acting like a giant capacitor and would a low pass filter fix this?

[@JohnAudioTech]

+zardozica The ground side of the cable (the shield) should be used to connect the metal parts of the guitar to help shield the electrical noise from the sensitive coils and amplifier input. Also be sure the amp is properly grounded at the power plug.

[@DonnieMulligan]

Did you connect the 100k resistor in series or parallel? I am doing a similar project.

[@seangonzales7236]

Hi john want to build a an amplifier using lm3868 but one of the part is very hard to find the Polypropylene (PP)0.1 uF 25 Vac 63 VDC Series: MKP416 , Manufacturer Part No: BFC241641004 what is the substitute for this part. thank you, your tutorial is very good

[@JohnAudioTech]

+Sean Gonzales You can get by with about any .1 uf film cap.

[@seangonzales7236]

thank you very much God bless

[@selvaselva1071]

Great video man lots of stuff in it.

[@silenozcefas1562]

Hello, I have that horrible noise I connect my turntable to a pre-phono in and out to a sansui amplifier on tape, even if I plugged in the ground wire that horrible sound follows, what can I do

[@andymouse]

Whats your favorite audio forum or channel please ?...cheers.

[@Kenshindegozaru]

Can you make one about the hiss? Im making a new cuad tda2003 that haves too much hiss, compared to a dual tda2003 I have from 9 years ago. Same inputs, inside a metal grounded box and all, but a lot of hiss. They are not bridged. They are 4 separated channels. They are cuad because Im making a crossover config.

[@djtazzmtl]

Hi John, nice video! I'm building a audio mixer using Tl072 op amps. I seem to be suffering from the 3rd problem. There's a low frequency buzz, butt everything else seems ok. Audio comes in clean, I do NOT get any kind of weird distortions or oscillations when touching the PCBs. So I think we are good there. My PCB is 4 layers and I have dedicated ground plane. I.e: Not using star ground. Also to note for now I'm using two AC/DC adapters as voltage splitter config I.e +15V virtual ground -15V. Any thoughts?

[@Canadian_Eh_I]

Did you find a solution? I have the same problem. Running 6 Icepower amplifiers active directly to the speaker drivers (2 3way) and I get a nasty everpresent 120hz hum. I think its coming from the boards.

[@robertneill3057]

Add rectifier diode decoupling capacitors either across the AC input (330nF to 470nF) or across each diode (100nF to 220nF). Would be stuffed if the mains adaptors are sealed shut. Most mains adaptors now have anti-tamper fasteners requiring specialized driver heads.

[@easygeorge3161]

I get a lot of humming while using my phone through the mixer ,, what device ,, which way is the best way around .. which isolator is the best one to use .. (inexpensive

[@afrog2666]

I like that you`re using a sony walkman player :) I have a model that isn`t available anymore, small touch screen one.. The battery has been dead for a whil, but I want to replace it, it`s a single LiPo I think, tiny battery, I think its about the same that is in yours. Does anyone know a place that ship those batteries to scandinavia? I can`t find them here in norway, and don`t want to order from china and wait 6-8 weeks :/

[@adeshization]

i am not understanding the star ground ... is it not that it is still connected to the same component and/or wire as the case may be .... or is it to make a shorter connection to ground so that it won't hum,osscillate or so ? hmmmmmmmmm ????????????????????????????????????????????????????????????????

[@HillOrStream]

Glebs Litvjaks Exactly. Actually the wires all have a complex impedance to be more exact, a combination of inductance, resistance, and capacitance

[@adeshization]

Glebs Litvjaks understood ... thanks ...

[@Indrajit9191]

Hi. Does a ground loop isolator also reduce the native sound quality of an amplifier?

I'm trying to reduce the noise of a PAM8610 module. I can reproduce this strange sound issue also when I touch the 3.5 jack input connector. When I increase the volume then the noise is also increases. How can I solve it? Does the resistor solve the issue? How to do that on this board? This is a picture of the module: www.haoyuelectronics.com/Attachment/PAM8610-Audio-Amplifier-Module/PAM8610-Audio-Amplifier-Module-6.jpg

[@arnoldbryansanchezcoila5753]

I have a problem when I approach a phone generates emaciated noise.

[@99hari55]

I have a tda2030 bridged amp total 4 ic .2 ic for each channel...its intermittend humming i meen creeeee ....high frequency sound for 2 seconds...why its happening...next is when i connect dvd player humming is high without audio signal....why....?

[@tigerelectronics5966]

Im currently working on a amplifier using the tda8561q chip, but I'm confused. There's a pin named Signal ground, should that be separate from all other grounds or should it go to my star ground point?

[@JohnAudioTech]

The pins must be tied together. However, the input signal ground lines should be returned to the signal ground pin. The power supply ground should be returned to the ground pin but do not connect it at any point on the trace the links the two ground pins together or on the signal ground side. The power supply ground should have its own trace leading to the ground pin. I'm assuming you're making a PC board.

[@tigerelectronics5966]

Thank you for helping me out! This is a question that has been bugging me for a very long time!

[@peteralexanderharrison9309]

I have a Marshall amp, the MP 50 FX, and I can’t get rid of the hum!!!!! Anybody have any suggestions, thanks a lot, Peter

[@raycasleong8325]

Thank you very much.

[@paweldun]

i put a 2,2k resistor crossing right and ground input and another in left and ground input and problem solved

[@saqibsami7967]

Hi, 2.2k tricks work only for mobile input. Speakers makes buzzing with noise when connected to laptop. Any suggestions ?

[@briggsmedia]

Great points - thanks!

[@prashanthb6521]

I cant thank you enough for this video sir, Subscribed, Thanks :)

[@jeetlodaya775]

Great video

[@MattMediaAU]

What's the name of your cat?

[@chrisremington2963]

my amp will hit loud than go to a low distortion,what could it be?

[@JohnAudioTech]

Could be a thermal issue (getting too hot) or instability.

[@chrisremington2963]

I burned the power wire

[@yomayraramireztopshelf3443]

I am having the same noise problem. I just wished I knew all this cuz I have no clue what your talking about ...help me plz...im going to do a video to show you maybe youll be awesome and help me....I am going crazy

[@VipulKumarOfficial]

How can i communicate u over email i hv some problem in my preamp schematic i want to show you

[@cinimax646]

Can I get diagrams?

[@rizsarwar2713]

hi try ferrite bead like the ones you get on tv power cables.

[@Radio478]

Thanks, very helpful

[@watup110875]

The first board setup, looks like some of my rat nest builds. lol 😄

[@snaprollinpitts]

thanks John

[@jonashinz3322]

„....yeah, this thing has issues...“

[@mohamedhomrani9251]

Great work %

[@jadimabuyu]

I have a LM1875 Amplifier which is our school project that outputs a buzzing sound when no audio is being played. When I reduce the volume the buzzing sound also reduce its amplitude. The sound is very good and clean when music is played. Can you help us?

[@JohnAudioTech]

The amplifier is just picking up electrical noise. Be sure the input wires are twisted together or use shielded cable all the way to the input connector. If the hum goes away when disconnecting the music source, then noise gets in from the music source or its wiring. You can try to reduce the input impedance by placing a resistor of around 4.7K ohms across the input.

[@jadimabuyu]

JohnAudioTech the input wires are twisted. I even tried removing the input wires itself the static is still present. Connecting a 4.7k ohms didn't also work. When I touch any ground points on the circuit the static stops but when I touch the positive input it intensifies the static. Is proper grounding the problem?

[@JohnAudioTech]

Sounds like you need to connect the amplifier's ground to a proper earth ground. Be sure the power supply your using is safe in doing this.

[@jadimabuyu]

Is there a alternate solution for this? In our country we only have 2 prong plugs. Nothing for earth ground. Thanks

[@JohnAudioTech]

When you connected the resistor, did you connect it from input line to input ground? What is your music source? If it is low impedance, like a headphone type music player, you can use a lower value resistor, 1K ohm or less. Touching the input and ground affects the noise like you say indicates a high impedance noise source and the resistor should cure that. It always works for me.

[@salahibrahim633]

Thankyou ihave this probleme but now is dispeared

[@aljivenalejo3904]

Well far more reason I do double impedance load just put under 22k ohms after filter caps And before filter caps

[@HimanshuSharma-dm8ol]

Good music

[@neodiy]

mini step down transformer and inductor will do the job much superior

[@electrolance7505]

I put notes for special traces on schematics for dumb pcb layout engineer to adhere

[@swagathunnithan5092]

This thing has issues🤣.

[@joohop]

your a good teacher my friend , have you thought about building bigger say 100 watts ATB

[@JohnAudioTech]

+joohop Please see my transistor amp video I did not too long ago. It is a discrete circuit that can make 100 watts with the correct output transistors.