Build a DIY Guitar Amp Mini Amplifier - LM386 Amp Head PART 1
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- čas přidán 7. 05. 2019
- Make a DIY Guitar amp! This mini guitar amplifier is easy to build and fun to play! The best micro amp is the one you make! This simple electronics project uses a LM386 amplifier chip with a real wood head and speaker cabinet. ➤Subscribe to my channel: goo.gl/p1xmZJ
Be sure to check out Part II to make your DIY speaker cab.
These amps have a great tone, and sound like mini tube amps! With a battery installed you can literally play your guitar anywhere. To Build this guitar amp, you'll need an LM386 chip, a dip 8 socket, capacitors(three), a 10 ohm resistor, some prototype board and 2 quarter inch jacks.
By request I've added some affiliate links(I earn a commission when you purchase here) to some parts, tools and amps:
🎸Cool little kit:
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📻Assembled amp boards:
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🎚Chips:
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🎸Mini Marshall:
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🎸Mini Danelecro:
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Tools:
🔧Solder:
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📎Solid core wire:
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✒Soldering Iron:
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Full parts list here and step by step here as well:
vintagemusictech.blogspot.com...
It uses recycled headphone speakers. - Věda a technologie
playing at the end was phat
Thanks Frank! i built it into a tea metallic box, with a few changes. I added some switches, LED on indicator and put an LDR between gain pins. Then i made a 555 oscillator and coupled the LED with the LDR so the amp has now a cool tremolo (i love tremolo, i could have tremolo for breakfast and lunch). I didn´t have the rheostat but used a 20k pot and it kind of works, need to improve that. Ah, and a capacitor in series with another pot, in parallel to the oscillator LED, so you can go from a square tremolo to more like a triangular one. Keep doing videos like this!
That sounds cool! I love trem too, and I like to put a switch between the gain pins for a bit of a overdrive pedal simulation. You could add a 10k and 1k pot to the legs of the output pot(10k in line, 1K to ground) Btw, I've been a fan of your "Abbey Road/ A Day in the Life" videos- really great work. New sub here!
@@FrankOlsonTwins thanks man, its mutual! I'll be changing the pots as you suggest
Thanks man, this was really helpful!!
Glad it helped!
Hahaha love it! Nice tones with your speaker too!
Thanks! The sound it records is bigger than it looks!
Well done!😊
Thank you! 🙏
Very nice video
Thanks for checking it out!
Hello Frank, I love this little amp and your instructions are great. I plan to put the amp in a small wooden cigar box to go with my cigar box guitar. I am wondering if I can replace a speaker at the output instead of a 1/4" jack?
Sure, either is fine. In this case, the jack is just a convenience to plug other speakers into the amp. Thanks for checking it out!
You should put a 300nF coupling cap between the inverting input and GND to stabilise the internal offset when changing the gain through pin 1 and 8, which would also make sense to couple instead of shorting to prevent affecting the AC. JohnAudioTech has a pretty good schematic for it. Also, I like your use of a 10 nF on the input to limit the low end so it doesn't clip as hard. The lm386 can have issues supplying enough current for the bass, which can be worsened further by having a speaker too small for it. That is, if you're looking for the best possible amp that is, if you want better overdrive, you've done it correctly.
Speaking of overdrive, you can make a pretty sick pedal with to 386's in series.
Yeah, I was going for "the simplest amp that remains stable." I've tried coupling the gain pins to each other with a cap, but didn't care for the limited response. But, I will have to try coupling the inverting input to ground. That might clean it up a bit in the lower volume ranges. Thanks!
It sounds a lot better than those cheap marshall style Chinese 3 watt 9v amps.
I have one that i bought solely for the purpose of putting a better amplifier into it, as the sound is pretty awful from the amplifier that's already in it lol
Agree, the stock LM386 chip amp is hard to beat for it's size, simplicity and price!
Great video, website and project Frank. Thank you off to Jaycar to buy some parts :)
Thanks! Good luck and let me know how your project turns out!
@@FrankOlsonTwins Hi Frank, can I assume that the 0.047 and 0.01 caps are uF ? Also would a 10K linear pot (rheostat) be suitable for the volume control ?Thanks
@@MrPnew1 Hey sorry for the late response- I just saw this comment.
Yes, all values are in uF. If you haven't purchased a rheostat yet, I'd say go for a lower value. The output impedance of most Lm386 chips is 8 ohms. You can match that closely to the value of the rheostat, which is why I'm using 10 Ohms. I'd say you could go up to 100 ohms or even 1K, but it might shorten the life of your chip. 10K might work or it might give you a limited knob range where the rheostat works in the range between 0 and about 100 ohms(just a guess here). Rheostats tend to be expensive these days($5+). The rheostat isn't necessary for a working amp, however. But it will make it easier to keep the crunchy guitar tone you want when you have the amp cranking.
Better if you'll add
film capacitor on 1 microF between 1 and 8 leg. And
emitter follower on the input.
Good advice!!
Hi there, nice little amp! ... what would be the best 3w (or even 1w) speakers for a guitar? i don't want it to sound harsh or distorted when playing high gain presets from my vst amp sims. Thanks!
Speakers are the most subjective thing about these amps. You can use this amp with anything from a 2" speaker up to a 4x12" cabinet. I'd look for a decent full range computer speaker to tear apart. The fun part is finding something unique to make a great sounding speaker/cabinet from. One thing I look for is All-paper speakers(no foam surround). I also like old alinco speakers from car radios, table radios or tape recorders. 1"x"5" ovals, 3"x5" ovals, 4", 5", and 6" round speakers all sound great with this amp. Good luck! I don't currently have a source for a "new" 3 inch paper speakers for these amps but I'm sure a bit of searching online will yield quick results. Good luck!
Perfect!
Can this build on lithium battery?
Sure, that would be fine if you keep the voltage between 5v and 12volts
If i can offer one tip, it's that a replacement tip for your soldering iron with a bit more thermal mass (larger tip) would make such a difference to your soldering. Won't make it work any better but would help you make it much prettier. I made the mistake of using the finest tip i could find for so long, moving up to a tip with a flat edge on it is NIGHT AND DAY. Anyway, i'm off to peruse your channel to find the video for the little speaker cabinet - i want to build something like that.
Good tip ;) I do like flat iron tips, especially for heavier things like cabling. Makes it a bit easier than having to "use the side" of the tip. Perhaps I'll get some with my next parts order. Thanks for watching!
Being a good bit older and shakier I tend towards as short a tip as I can get. I am recently retired from Boeing where I worked on R and D, most of my soldering was on 34 to 48 Guage mag-wire and micro strain test so my joints were about a mm in size or less. I prefer to use Weller stations with tips that only stuck out about an inch or so from the handle.
Have you ever built the ruby or noisy cricket amps? I believe they are very similar but those have a pre amp buffer section, just wondering if they make much difference to the sound.
Nice concise video btw, great looking project
Yes, I have built the ruby. It's worth building one to see if you like it, but I tend to stick with the simplicity of the straightforward 386 builds. Thanks for watching!
@@FrankOlsonTwins thanks for the contents and the quick reply!
the out put jack can be use with headphone ?
Generally yes, It will work with headphones. It might be too loud for many heaphones, so use the volume control to check the level.
can you use this circuit as a pre amp and run it into a second circuit... or even 2 circuits to 2 speakers ?
yes both options are possible. i have a live video about making one of these into a fuzz style pedal, which is similar to a preamp you're describing. There are many stereo circuits for the lm386 online, you should be able to find something without too much effort.
i want the material in the board simplified pls
Is there maybe a breadboard diagram?
So interesting. Which is the output impedence? Does it work even on a regular 4x12?
I believe the impedance is 8 ohms. You could safely drive pretty much any cabinet with this, from 4 to 16 ohms.
I was wondering why you coiled the positive wire around the ground wire on the output jack, is it to increase the current? The reason I asked is because there is a guy here on CZcams that some people say is a second Tesla who says you can multiply the current by winding a wire around itself and that the output current is multiplied by the number of turns that the wire is wound around itself. I was always taught that current cannot be multiplied by a transistor is supposed to do that. Thanks and thanks for the video.
I twist some unshielded wires together to try to cancel out hum if it gets picked up by the positive output wire. The grounded wire on the output will act as a shield to some degree.
Could you please explain a little bit more what you are trying to say or tell me what video to look for?
@@libervolucion Long story short : When the current flows through a wire, it generates an electronmagnetic field around it which has a determined direction of rotation according to the direction of the current (Ampere's theoreme). Coiling positive and ground wires, travelled by same current but in opposite direction, will generate 2 electromagnetic fields that will counter each other so there is almost no more electromagnetic field. It is done to avoid electromagnetic disturbance in the circuit that could lead to sound distortion.
Can I use a 120v power running through a transformer stepping down to 12v to power the amp?
Sure, but you'll have to convert it to DC, and you probably don't want more than 1 or 2 amps current. That's exactly what most wall wart "transformers" do.
Hi, does it work if I add an alternative 1/8 in jack so I can play audio straight from my phone using headphone jack without any adapters?
Yes, but you might need to use a stereo input jack and run both of the signals to the input of the chip. You'll get a mono sound, but then you'll get both stereo signals. The alternative would be to build 2 circuits and hook each up to it's own speaker for stereo.
@@FrankOlsonTwins I see, thank for your explanation,
Does the amperage of the circuit depend on the wattage of the speaker? like having a 10 watt speaker on a 9v power source makes the circuit draw 1.1 amps?
i am very new to electronics, sorry if its a stupid question.
Hi, good question! The concept you're referring to can loosely be called output drive. It is affected by the voltage, as you suspect, higher voltages require more current/amps. However, the chip itself is designed to have certain properties such as current draw. It's usually stated on the data sheet for the chips, so designers know the maximum limits. They ratings are usually in milliwatts or watts. External things will affect output drive slightly, such as a very high or low speaker ohm load, but speaker wattage isn't really a factor.
As a side note, generally speaker wattage has little effect on an amp, EXCEPT when it's too low. A speaker that is totally overdriven will eventually burn up the voice coil.
@@FrankOlsonTwins Thats interesting, so hooking up a 10w speaker and a 100w speaker dont really affect the circuit?
will they sound different? or up to a certain wattage they wont be driven as much as they should?
Yes, they will sound different but they will both work. Speakers are rated for efficiency, and a large 100 watt speaker will generally be less efficient than a 1 watt or 10 watt speaker. So, yes you can hook these amps up to a 4x12 cabinet, but they will sound different than listening through a smaller speaker. Whether they sound better or worse depends entirely on the speaker and the listener!
Hi! Are you using a pedal or is the distortion from the amp? Tanks!
Amp only, the pedal is a high gain switch!
I only have 1/4 watt resistors, is there a good substitute from the 1/4 watt range that will work?
You could try making this with 1/4 watt resistors. I'm sure that would work fine. Or, you could double them up to make 1/2 watt values.
I have to troubleshoot everything now, built it all with no results.
1 - 220uF eletrolitic
1 - 100nF ceramic or poliester capacitor.
Both in parallel in the vcc in. Respecting the eletrolitic polarity sure.
1 - 10 ohms + 57nF from pin 5 to ground.
If you're using lm386-N for sure.
👍😆
U'll have a cristal clear sound
And if u wish gain just insert a 4k7 pot + 10uF eletrolitic from pin 1 to pin 8.
👍😆
Does it work on an semi acoustic guitar
yep!
Great project. I can't wait to try it. I was hoping to use a 4ohm speaker I already have, and solder it to the output for a stand-alone amp instead of using a separate cab. You mentioned that pretty much any size speaker would work; does the same go for the impedance?
Also, I wanted to add another pot for tone control. Any advice?
4, 8, or 16 ohm speakers should all work just fine with the amp. You'll know if the amp doesn't agree with the speaker because the tone will start to sound really muffled or really thin.
As far as the tone pot: you could try one before the input or at the output. Think about how a guitar tone knob works, that'll get you in the ball park.
Let me know how it turns out!
@@FrankOlsonTwins Thanks so much for the reply. Waiting for parts to arrive, but I'll let you know how it goes.
*Subscribed*
i want to try it too, i want to see the schematic.
Do a google search for the Lm386 datasheet, in the applications examples you will find the schematic for a 50 gain and a 200 gain circuit
That's basically what I do for every project, download the datasheet and compare it to few schematics. Data sheets are a great way to get all the pertinent info for a given chip/tube/circuit/component.
What are the SPECIFIC materials you used? What kind of transistors, capacitors etc.?
Hey Dabi, check the link in the description, it has a full list of the exact parts needed to build the amp. vintagemusictech.blogspot.com
Yes, these caps are measured in uf. 25 ohm rheostat for the "output" pot, 10k might not work well. If you can't find 25 ohm you could use 8 or 10 ohm. In fact, you don't "need" the rheostat, if you are willing to use your guitar volume for the gain/volume. Check oft the "smokey" amp, they have minimal parts- no pots.
is the 9v input source ac or dc?
DC.
do i need to put a variable resistor from pin 1 and 8 to control the gain?
Up to you. You could put a jumper there to make it "Full gain" or you could leave it open to set the gain to "twenty percent." Personally, I prefer to use the full gain jumper and just use my guitars volume knob to control the gain. A variable resistor will do control the gain the same way, except it won't interact with your guitar's pickups. I don't usually bother with it though. I just jumper the pins.
@@FrankOlsonTwins thanks, looking forward to your future projects.
So could you in theory hook that head up to a cab? What’s the impedance?
Yes, pretty much any impedance from 2 to 16 ohms. And it will be pretty loud!
@@FrankOlsonTwins don’t the impedances have to match or it will damage the cab?
With a small, solid state device such as this- the impedance is a non-issue really. It puts out around 1 watt or less and you won't risk damaging the cab. You might notice a different sound if there's a big mismatch(for example, a 2 ohm or 32 ohm speaker), but that's about it. Theoretically, I guess you could burn up the chip if the impedance is too low(like less than 2 oms) but even that seems pretty unlikely.
However, with any higher powered amps always stick to the impedance recommend by the manufacturer.
@@FrankOlsonTwins ah okay, I understand. Your advice is much appreciated! Something like this will make messing with audio circuits MUCH easier!
can sound be clean? or it is always distorted, how can i change it
Change the gain/distortion by changing the gain resistor for the chip. I used a "Jumper" for full gain. In that case, it will always sound distorted. If you use a potentiometer you can change the gain by turning the knob to clean up the sound to your liking.
What value should it be?
Hi, great video! Can i use a Headphone jack instead of a Speaker in the circuit?
Sure! If it's too loud you might need the rheostat option(the last connection in the video), or add a 10 ohm resistor to ground right before the output (headphone jack). Check out where the 10 ohm resistor is added here: www.minidisc.org/schem.gif. Or you could add it between the speakers positive and negative terminals.
@@FrankOlsonTwins Thank you!
no problem!
Can I use a tube rectifier as power supply?
I wouldn't... You only need between 5v and 18v. You could get that from a free/cheap wall wart at any thrift store!
thanks!
@@FrankOlsonTwins
Can we use pedals?
Sure, it takes pedals pretty well!
Build it works nice but potentiometer didnt work.
Would you please show it clearly. can i use 50k ohms poteintiometer
Hello,
A pot isn't required. You can use your volume control on your guitar to control the volume. Unfortunately a 50k Ohm pot will probably not work. You need a 10 or 20 ohm rheostat, which is like a wirewound potentiometer.
Can you name everything in there in here (written) plss🥺
Does it work in an Electric Violin?
Sure, it should work fine with electric violin!
@@FrankOlsonTwins do you have a list of components?
Full parts list here and step by step here as well:
vintagemusictech.blogspot.com/2019/05/make-mini-amp-for-guitar-lm386-chip.html
Don't forget to subscribe! ;)
What is the power supply on this?
Any d.c. voltage, 5v-18v. You can use a phone charger brick, pedal power supply, 9v battery, etc.. most common is 9v battety.
Does this mini amplifier have a pre amp stage in it ? If it doesn't, do you connect one off screen or did you connect the mini amplifier directly to the guitar jack?
Everything is as you see it in the video. The amp needs no preamp; it's already inside the chip. The output goes straight to the speaker. Here's another way to think about the hookup: czcams.com/video/Ts4dBCGG4rk/video.html
Ow! thanks for responding. you don't know how much helpful your work is. I have another question about the power device (the power source) that you talked about. what is it? its voltage, current output..ect , can i use a simple 9V battery, for example, instead?
Yes, a 9v battery works perfectly. Alternatively you could use any power supply from 5 volts to 18 volts. Very small current is required, you could run it off a any wall-wart style brick with 500mah. But really, most people just use a 9v battery. Good luck!
@@FrankOlsonTwins Oh I see, a 9V battery would be easier to obtain. i wanted to ask you too about if you have a schematic representation of the circuit, something more detailed?
Look up the Little Gem amp. Similar schematic.
Hi.
I do not recomend bending the pins beneath the board. It will be difficult to ŕemove the component in the future. 👍😆
Jinete denso
is it 12 v or what?
Most of these chips are between 5v and 18v. Some variants are 5v to 12v. This one is running at 9v.
Will this work if I make a cab with bigger speaker?
yes, any size speaker will work. It will even work with a 4x12 cab!
@@FrankOlsonTwins that's really good to know! Thanks for the info. Also what about connecting the amp through a powered speaker? Like a Bluetooth speaker that's not broken? Will it work or will it break the speaker?
That could work if you keep the mini amp volume low. There might be an impedance mis-match, so it might sound bad. I don't think you'd break the blue tooth speaker, but you might wreck the blue tooth amp.
@@FrankOlsonTwins hi sorry i have questions again. I got this old speaker and opened it only to find some kind of circuit. There were capacitors and resistors. Should I take them out or can I leave them be and just plug the amp to it?. It is a passive speaker by the way. Also I can use a 9v PSU instead of a battery right? Sorry I'm really new to the DIY world
No problem! There's no harm in trying to see if it works as is. It might work fine with the little circuit engaged. But if it doesn't simply remove all of it and go from there. And yes a 9v psu will work fine instead of a battery. Good luck!
Is the LM386N-1 or LM386N-3 better for an amp like this?
I've used both, they are both fine. The N-1 is about half as loud as the N-3, depending on the speaker you use. I run either one off of a 9v power supply.
@@FrankOlsonTwins okay thank you!
@@FrankOlsonTwins is there an LM386 you like the best for an amp like this?
Good question. I usually like these amps to be pretty quiet, so I go with the LM386N-1 and I use small speakers( 2" speakers). You can always plug it into a bigger guitar cab and it will be louder, but for me I like a desktop amp to sound like a small amp. Also, I find the smaller sound inspiring when playing. You could buy one of each chip and switch them out(make sure you use a socket, that would be easiest). Then, you can get a feel for which one works better for you. I think the chips are about $1 each, and sometimes less. When I order, I do sometimes order spares, in case I accidentally touch the pins on one while installing. That's a quick way to kill the chip!
@@FrankOlsonTwins Okay thanks I'm making a cabinet with a 6'' ill send a video when I'm done
I have built 5 circuits similar to these and all of them don’t work,
I have one that works that I found in a box of old electronics that is similar to this circuit why does that one work and all the ones I have built not? I know my chip is fine
Hmm, hard to say without seeing the circuits. But, I've had chips go bad simply by touching the pins. It can happen quickly, and you might not realize you did it. If you've triple checked your schematic and your other parts all appear to be good, I'd try a new chip.
Also, it's good to swap out the electrolytic capacitors for new ones. If they over heat, they can hum or simply stop working.
How much did this cost to build
Approximately $10 dollars plus the cost of shipping the parts, if built as shown.
$1 only amp without jacks and case
@@Kojima_dreams WTF? Really?
@@Kojima_dreams really? Pray tell. Did they fall off the back of a truck 😎
@@MrPnew1 you can buy imported assembled amps like this for about $1 each, check out ebay. But it's less fun and less educational;)
built it and it didn't work. Would you happen to know what went wrong?
Triple check every joint against the schematic. Mark each correct one with a highlighter. Make sure the polarity of the electrolytic caps is correct. Make shure the polarity of your power cable is correct. Also check your output wiring and speakers. If it still doesn't work try a new chip. Some are extremely sensitive to static, if you touch the wrong pins with a charge on your hands, it won't work. It's happened to me several times.
@@FrankOlsonTwins Okay, thank you! Will this work if I plug it into a guitar amp? Or do I specifically need a cabinet?
If you plug it into a guitar speaker it will work, but if you plug it into a guitar amp (specifically, if you plug it into the input of a guitar amp) you will likely destroy the input stage of the next guitar amp. These generally put out about one full watt , which is suitable for speakers but not other device inputs.
And so would it work if instead, I soldered a headphone jack where the speaker cabinet was supposed to be soldered in? Or could I not replace a headphone jack with the mono jack?
Yes, you could hook up a headphone jack up in mono, by connecting both positive(Left and right) contacts to the positive output wire. It will ne very loud in the headphones, so be careful with the volume!
Where does the output jack go, where does the rheostat go what is the jumper from 1to 8 for , which capacitor what side cmon man you talk like we already built it. Be specific.
You make some good points! I included the schematic/layout at 00m:21s to "fill in the gaps" of the assembly. I drew the schematic as a layout which would look similar to the assembled circuit. So, if you follow along with the schematic, it makes the build more understandable. Generally, when I'm building any circuit, I print out the schematic and the layout(often they are different) so I can get a firm grasp of what part goes where. I omitted the Rheostat from the schematic for clarity, as I know most people won't use it(it's not really necessary). It sits between the capacitor and output jack. That's why one leg goes from the output capacitor to pin 1 on the rheostat, and pin 2 connects to the positive output jack. For the output leg of the capacitor, I'm referring to the capacitor on the schematic that says "out"(220uf).
The jumper from 1 to 8 controls the gain, so open would be gain of 20, closed would be gain of 100. So, when it's jumped, your guitar volume becomes the gain adjustment.
There's a more complete assembly guide at vintagemusictech.blogspot.com/2019/05/make-mini-amp-for-guitar-lm386-chip.html