Class AB Audio Amplifier LM3886

[@davidluther3408]

GOOD ILLUSTRATION BUT BUT,WITH THE THERMODYNAMICS PART YOU ARE MAKING ME TENSE.HOW WOULD THIS WORK IF YOU HAVE 8 OHM SPEAKERS? IT SEEMS YOU WOULD ONLY BE GETTING HALF THE WATTAGE.

[@KissAnalog]

Thank you! Without heat sinks, they do get hot pretty fast. At this point it is well below what this device can do, so I think it would put the same power out at 8 ohms to get the same temp;) I’ll get heat sinks on it so it can put out max power - I hope:)

[@barneylinet6602]

These are rated a 38 watts RMS into 8 ohms. Figure that a class AB amp will dissipate an amount of heat equal to the RMS audio power, or roughly 38 watts of heat at full output. For two amp chips this is 74 watts of heat! You need a BIG heat sink!!!!! If these chips get too hot, they go into protection mode and then you will get lots of distortion. I would recommend a finned heat sink about 30 square inches as a conservative design. If you are driving 4 ohm speakers you need a heat sink twice as big.

[@KissAnalog]

@@barneylinet6602 Thank you - that is great information!

[@24tcwarrior]

I have a question, when chosing a power supply for a rail to rail op am (LM3886) do we care about the current flowing into the supply voltages inputs (should there be any current or none), if the input voltage is independent from the input signals? I am looking for power supplies that can produce +/-24 Vdc but I am not to sure if we care about current. As well as, does the current from the power supply effect the output current from the LM3886? Meaning if we wanted something like a 5 amp output, do we need a 5 amp power supply with the specifications of something with outputs like +/-24 VDC, 5 Amp, 120 Watt?

[@TRONMAGNUM2099]

I was going to tell you to try this amp. I just got a LM3886 amp kit. So far I am liking it. I think you and JohnAudioTech need to do a collab. As far as I can tell you guys have the most informative channels when It comes to audio.

[@KissAnalog]

Thank you so much!! John and I are just now working on a way to collaborate;) I love his Channel!

[@IceTorch051]

For a complete test you will need a heatsink so the amp doesn't overheat and a speaker. Using a resistor for load is not sufficient because resistor doesn't give back EMF like a speaker does. And btw, it's always a good thing to have a low pass and high pass filter on the amp. Few years back one lets call it night club has replaced 10 HF drivers in about a month. I came to check what was happening since they were using our speakers, and they don't break often. Their technician would just replace the bad driver and call it a day. What was burning the tweeters was their cheap amplifier, which on its own is a fine amplifier, but it didn't have a low pass filter on 20 kHz, and one of the dimmers was inducing a lot of noise at about 40 kHz or something like that. That noise was picked up by non balanced audio cable and amplified amplified it and send to a speaker. Nobody could hear it, but the tweeter was getting full constant power from the amp when the amp was turned all the way up, and over time it would burn the voice coil of the tweeter. We upgraded the input with balanced cables, since the amp had balanced inputs, and put the LP filer on the input of the amp. The problem never happened again.

[@KissAnalog]

Thanks for the great feedback!! I’ll have to get some new videos up and I’ll be happy to hear more great information!

[@versace885]

Hi Eddie, I like the detail description and I love your enthusiasm. Thank you for a another great Video.

[@KissAnalog]

Thank you! I appreciate it!

[@TuiCatNZ]

Neat board. Very flexible ac voltage input. 20-94volt according to spec sheet.

[@KissAnalog]

Thank you!

[@sc0or]

If you check the datasheet it better works at 35V. Any other voltage will cause bigger distortion at high power (>40-50W depending on a load resistance).

[@KissAnalog]

Yes, but I was keeping the voltage low enough so not to distort and I think it was high enough to bias everything well enough. It actually tested pretty good don't you think? Thank you for your feedback - and I will test this amp again as this is one of my favorites right now.

[@sc0or]

@@KissAnalog Yes sir ) I'm thinking about this amplifier for my DIY project during a lockdown. Your information is appreciated.

[@KissAnalog]

Thank you!

[@wimpep1388]

Great video! I am just surprised about how far the gain setting resistors are from the LM3886 chips also the buffer caps are quite far away. In all the datasheets and design notes they outline everywhere that these components should be placed very close to the chip to prevent oscillation. In any case the amp seems stable, I wonder now how important that is.

[@KissAnalog]

I’ve been looking at this and it is interesting. It is fairly small board and not a lot going on so it is probably ok some cases not to have an ideal layout. I’m like you - I like to keep things tight and I know you have lots of experience from watch your channel - which is one of the best on KZbin!!

[@TheChariot7]

Sir I want to know whether the board will be delivered in India and what will be the charges.

[@KissAnalog]

Thanks for asking! Do you have Amazon or ebay there? If not do you have alibaba or aliexpress? I'd be very interested to know how our friends in India order this type of thing.

[@sesioramadhan5137]

brother, can i get the schematic and The PCB layout?

[@frontier9]

He didn't make it, would have to reverse engineer to draw it up.

[@KissAnalog]

Yes, thank you - I was waiting to respond so that I'd have time to reverse engineer;) I'll get back when I have more info.

[@shean-koklim4197]

fantabulous, thanks!

[@KissAnalog]

Thank you!

[@paulwarwick2540]

Hi, been learning a lot from your channel last few months, so thanks for all your effort ... , I now have this board and a Kaiweets desk supply to begin my journey. If I wanted to review building the power supply into the board, do you have a video about a power supply that would best suit this board? Would it be DC like the test or AC?

[@KissAnalog]

Thanks Paul! Sounds like you are having fun. Do you want to use DC or AC power?

[@paulwarwick2540]

@@KissAnalog Cool, so as a novice the best pointer would be one where you feel a simple solution would give a decent result from this particular board. I'm in the UK so AC will be 240/220. I've found lots of kits and have several old items that have boards that convert to DC. What i'm probably missing is enough understanding which approach would be best for this board ... it seems like managing the AC voltage straight into this board would be simpler? Ultimately im looking for this project to allow me to replace components one at a time to see how I like the sound ... once again without your channel I wouldn't have made it to this basic level , tyvm

[@newENIO11]

how do you bypass the preamp section?

[@newENIO11]

is it as simple as moving the jumpers?

[@KissAnalog]

The jumper labeled GND and IN - I think you use those to run your signal into (removing the jumper). Otherwise the pin labeled Out is the output of the preamp and that is jumpered to the IN pin. Does that make sense? check the traces on the bottom of the board and you can see which way the route. Let us know if that works for you;)

[@DandyDon1]

The LM3886T was at one time manufactured by National Semiconductor. This board is no longer available from Amazon.

[@KissAnalog]

Thanks DandyDon! Here is one that looks good too: amzn.to/3yYm7ip

[@DandyDon1]

@@KissAnalog Just like batteries...... Heat Sinks not included, but definitely needed. :o) What I do not see though is a connection for the mute feature. A design which was used in a musical instrument product required 40v DC to operate it. I don't know how 15v DC is enough with this design on Amazon.

[@billkalina3089]

Hi! I assume you can bypasss the input stage if you have a preamp?

[@KissAnalog]

Great question Bill - thanks for asking. Yes, there is an input port for a preamp input.

[@teamnery1747]

@@KissAnalog is it as simple as moving the jumper?

[@KissAnalog]

Sorry I don't get good notices for comments under others... yes, it is just where you plug the input into.

[@friedmule5403]

Great video again as always, glad you again did explain your setup and the important details all the way, like heat, scope readings and 60 deg is autch temp! :-) When I see how small this amplifier is and how few components it is made of and compare that to some of the amplifiers you can buy where they are the size of 2 shoe boxes with over 1,000 components and 80 Lbs, I can't help wondering the reason. Can you maybe please explain why?

[@KissAnalog]

Thank you Fried Mule! Yes that was hot;) I’ll get a heat sink on it for the next video... when I show the data sheets, it will help explain how these replace so many parts. Also, I’ll add an ac power supply, so that will add parts and weight.

[@friedmule5403]

@@KissAnalog So the reason is that a lot of these components are integrated in to the chip (IC):-) But that have to be both good and bad, wary easy to use, almost all parts in no space. Against that you can not select your own PNP''s, resistors or op-amps and that gives a lot less design freedom but do on the other hand, save you a lot of money:-)

[@versace885]

Hi Eddie, I also want to tell you, I like the way the screen comes on, hee hee

[@KissAnalog]

Thanks! LOL

[@justinmurphy2227]

ANY class amplifier needs a heat sink from the start at any voltage or load. I'm surprised that the KZbinr (sorry no one shares their name) was, surprised, by this. These are designed to be put into a case with a heat sink immediately as drop-ins.

[@KissAnalog]

Yes you are right! I was trying to show how very little power heats this up, and how a heatsink was needed. BTW, I give my name at the beginning of the videos;) Eddie Aho, and here's a link to the follow up with the amp mounted, for test, to a heatsink: kzbin.info/www/bejne/oXelq2NrmsqLnLM Thanks for the great feedback - Hope to hear more from you soon!

[@justinmurphy2227]

@@KissAnalog I compete in car audio and would love to build my own amplifier. I know they make mono, full range, already assembled DC amplifiers. I run 4 speakers for my front stage....2 wideband 3" drivers that play from 250hz to 20khz. Then, for midbass, two 7.1" mini woofers. My sub is a 15" which I will power with one of my 1k watt amplifiers. I want to run one mono amp per speaker for my front stage. I'm meeting around 75 to 100 watts from each amp. Help me with this project sir! I've had 3 spine surgeries with 2 multi-level fusions. I now have nine screws of which three have backed out and need surgery again. Thursday to see what the plan is. I'm very humble would love some help to find these for amplifiers and build some type of heat sink for them. Maybe I can work with you on a video and get my first video out there as well LOL. you obviously have the equipment and know what you're doing and I could have many many more projects for you which could easily turn into videos! My email is [e-mail] and my Facebook profile where you can message me from.... facebook.com/profile.php?id=1648520005 Thank you sir.....so much!

[@KissAnalog]

Thanks for the great ideas! I’ll email you. My last few weeks have been crazy busy, but I like your ideas! I hope the surgery plans go well - sounds painful - I’m sorry.

[@davidluther3408]

WHAT I MEAN IS MOST SPEAKERS ARE 8 OHMS,SO IF YOU USING 8 OHMS THE DATA WILL BE DIFFERENT.

[@KissAnalog]

That’s true David. I’ll put a heat sink on it and give a more complete test. Thanks for commenting!

[@huyhoang88gemstone]

tôi có thể dùng nguồn đôi 40vac cho nó được không. thanhs

[@afaudioelektronicprojeck]

Mr. Minta sekema dan layoutnya...driver amplinya

[@KissAnalog]

Thanks!

[@yourajbadgujar7837]

which class is best for high quality audio?

[@KissAnalog]

Class A is what most prefer I think but I think class D might be better for high power.

[@pa3eka]

Good hot amp ? Or Good heater with amplification Lol

[@KissAnalog]

Yes Bert - a double benefit;)

[@iLuvSoldering]

Real hot

[@frontier9]

I'm surprised you didn't put a heatsink (at least so far into the video) 10.30

[@KissAnalog]

Thanks Michael! I made a couple more videos on this amp. Here’s one with a heat sink:). Class AB Heatsink LM3886 kzbin.info/www/bejne/l5nadXqsiryEb80

[@barneylinet6602]

I'd rather have a pair of Macintosh MC 30s. Only a two orders of magnitude difference in cost. Performance is similar......

[@KissAnalog]

Hi Barney - I used to have a pair that I recapped, but they were stolen:(

[@user-Steppo_Tilli]

Why investigate a deliberately fake microcircuit on a deliberately incorrectly wired board? .. For video?

[@KissAnalog]

Thanks for the question. Why do you think this is a fake microcircuit? Why do you think it is wired incorrectly? It seems to run great. Have you seen the other videos in this playlist? kzbin.info/www/bejne/oXelq2NrmsqLnLM

[@user-Steppo_Tilli]

@@KissAnalog Because the board is from China, and the originals do not come from there! I don’t understand why the world doesn’t ignore the Chinese market of radio components? Greed prevails and you want to buy for nothing, but only cheese in a mousetrap is for nothing!))

[@elektron2kim666]

I think you ruined the video with the oscilloscope filling up 10 minutes. Texas Instruments don't lie much.

[@KissAnalog]

Sorry about that. What part should I have left out?

[@elektron2kim666]

@@KissAnalog As an example, I understand any graph without knowing all the buttons and functions on that machine. Maybe it's me. I think I would record some music through the wires.

[@KissAnalog]

Great point - thanks!