Build an Inexpensive Powered Speaker | Make:

By Ross Hershberger
Time Required: 6 hours
Difficulty: Hard

Print this Project

MonoBox is a small, inexpensive powered speaker that amplifies the output of your headphone music player. It’s little but it’s loud! All the circuit parts are available from RadioShack. The speaker and cabinet are left to your preference.

You’ll learn how to assemble and solder an audio power amplifier using an integrated circuit (IC) chip, and how to choose a speaker and install it in a cabinet with the amplifier.

The core of MonoBox is a compact and efficient audio amplifier based on the LM386 power amp chip. It will run on 200mA of current using power supplies from 6V–15V DC. This gives you the flexibility to power it from a wall adapter, a 9V battery, or a car accessory outlet.

You’re probably thinking, “Sure, but it’s so small. Does it rock?” Fair question. The prototype has been exhaustively tested and it does indeed rock. Maximum volume output is 90dB, and with the added bass boost your socks will be rocked clean off!

December 18, 2012, 11:02 pm PDT

Parts
/
Tools

Parts

Nuts, for machine screws, #6-32 (2) from RadioShack.
Washers, for machine screws (2) from RadioShack.
Machine screws, #6-32 × 1½" (2) for mounting the circuit board
Fabric or screen, acoustically transparent, for the speaker grille
Box or other enclosure, approx. ¼ cu. ft. from RadioShack.
Dacron pillow filling, about ¼ cu. ft. for stuffing the speaker box
Machine screws, nuts and washers, to fit your speaker and box (4) for mounting the speaker
Standoffs, plastic, ¾" long, to match #6-32 screws (2) for mounting the circuit board. I made my own from ¼" plastic tubing.
Power plug, DC, (optional, for 9V battery) size N, coaxial from RadioShack.
9V battery, (optional) from RadioShack.
Battery holder, (optional, for 9V battery) from RadioShack.
Battery snap connector, heavy duty, (optional, for 9V battery) from RadioShack.
Sheet cork, solid cardboard, or foamcore board, (optional) to fabricate a speaker gasket if needed
Audio cable, ⅛" stereo plug to ⅛" stereo plug from RadioShack.
Wire, solid core, 22-24 gauge, in a variety of colors from RadioShack.
Loudspeaker driver, full range, 6Ω–12Ω impedance, 87dB sensitivity
Resistor, 10Ω, 1/4W, 5%, R3 from RadioShack.
Resistor, 10kΩ, 1/8W, R2 from RadioShack.
8-Pin IC Socket from RadioShack.
Audio amplifier IC chip, LM386, low voltage, 8-pin DIP package from RadioShack.
Printed Circuit Board, general purpose, for ICs from RadioShack.
Audio jack, stereo, ⅛", panel-mount from RadioShack.
Resistor, 100Ω, 1/8W, R1 from RadioShack.
Capacitor, 0.01µF 50V 10%, PC mount, for C1 from RadioShack.
Capacitor, electrolytic, 470µF 35V 20%, radial lead, C3 from RadioShack.
Enercell™ 9V/300mA AC Adapter, or suitable 300mA power supply with 6V to 12V DC output and type N center-positive plug from RadioShack.
Capacitor, electrolytic, 100µF 35V 20%, radial lead, C4 from RadioShack.
Capacitor, 0.022µF 50V 10%, PC mount, for C1 from RadioShack.
Capacitor, 0.047µF 50V 10%, PC mount, for C2 from RadioShack.
Power Jack, DC, size N coaxial, panel-mount from RadioShack.

Tools

Crayons and paper
File, round, tapered, small
Helping Hands tool from RadioShack.
Hobby knife from RadioShack.
Hot glue gun or caulking gun
Magnifying glass from RadioShack.
Marking pen
Pliers, needlenose
Rotary tool with cutoff wheel from RadioShack.
Ruler
Sandpaper, 100 grit
Scissors
Screwdriver
Solder, rosin core from RadioShack.
Soldering iron from RadioShack.
Wire cutter/stripper from RadioShack.
drill with drill bits

Steps

Step #1: Select your cabinet.

NextPrev

There are many options for housing your MonoBox. I've used nice old wooden cigar boxes; you could also use a lunch box or small toolbox. Choose something between ⅛ and ¼ cubic foot (equal to 6"×6"×6" and 6"×6"×12", respectively). Make sure it's deep enough for your desired speaker, and has one surface suitable to mount your speaker on.
NOTE: A box that can be tightly sealed against air leaks will provide the best bass sound.
Wood and plastic are good cabinet materials, as they're easy to work. Metal is more challenging. Almost anything relatively rigid can be used. Construct a box from cardboard in any shape you like, and cover it with colored duct tape!
RadioShack sells two project boxes that are about the right size. They're made of black ABS plastic that's very easy to work. They measure 7"×5"×3" for model 270-1807 (shown here), or 8"×6"×3" for model 270-1809.

Conclusion

Going Further

What if you really want stereo? Make 2 MonoBoxes! In each, connect only one channel (left or right) of the input jack directly to the amplifier circuit board, and use a SPST switch to connect or disconnect the other channel, so each box has its own mono (or 1-channel) selector switch.

Set both boxes to 1-channel, then use a stereo headphone splitter to connect both MonoBoxes to your music player.

Ross Hershberger

Peter123

To power the speaker you could also have a solar panel on top so during the day you can switch from battery power to solar power by just adding a switch.
fontmark

Found the diagram in the PDF.
- gbelectronics
  
  this wouldn’t work in britain would it. any suggestions on how to make it work. also dont know where id get the components
  - ALRUI
    
    No reason it wouldnt except youd need an adapter for the power brick (one of those travel adapters). Should be an electronics shoppe or order off the web.
Nick Normal

hi saulx350z, the diagram is one Page 2 of the project: http://makeprojects.com/Project/MonoBox+Powered+Speaker/2396/2 – it’s Step 15, or, if you can’t see that for some reason, here is the image: http://guide-images.makeprojects.org/igi/X3WB2Tny1O2xSlQb.large – hope this is what you were looking for.
Ross Hershberger

Volume: I measured peaks 90dbs at 1 meter distance before distortion set in. This was with an 8 Ohm speaker of mid/high efficiency. Not enough to throw a disco party but way above a typical computer speaker. I recommend a wall-wart power supply rather than a 9V battery for extended high volumes. Uses a lot of current.
Ross Hershberger

It depends on the speaker. A larger speaker may have reduced high frequency response unless it’s designed as a full-range driver. If you’re unsure I’d say build the amp circuit alone and try it with that speaker mounted on cardboard as described in the article. if you don’t like it you can change to a different speaker for the final assembly.
Ross Hershberger

I wish I could give a full answer. Do you mean it plays at low levels but stops completely when the volume is turned up?
Ross Hershberger

Note that a number of the Radio Shack parts like the circuit board and some of the resistors come 2 or more to a pack so you won’t have to duplicate the whole list when making 2 amps.
ambrosehone

Also, I guess I would also need to adapt the power for Australian sockets.
ambrosehone

*Complete Battery Overkill*
Also, I guess I would also need to adapt the power for Australian sockets. Hmm…..
Ross Hershberger

Stereo is covered at the end of the article. The LM386 amp chip has only one channel of amplification. The easiest way to go stereo is to build two of them. You have to make a small modification to the circuit at the input jack because the stock mono circuit connects right and left together. You would want one built with only the right channel connected and the other built with the left connected. Option: install a switch at the jack so you could switch to mono operation by connecting in the other unused channel.
tripsofjacks

I went into radio shack today and they had no problem helping me find all the items on the list. I’m going to build this over the next couple days. I found this on flipboard and thought it sounded too awesome not to try… I have never done a project like this, but your instructions appear well done. I will post on the outcome when I am done. Thanks for sharing this project.
tripsofjacks

My project is a sucsess, my amp is working well, and is really cool!!! Much thanks to the author for sharing these awesome and easy to follow plans!!!
Ross Hershberger

Note from the author here. I’m abruptly out of the country for work and have unreliable internet. Apologies for the lack of replies. I will read all responses and answer as soon as I’ve sorted out certain industrial laser issues and made my back north of the border. Thanks. Ross Hershberger
- rkan665
  
  so, when i plug in my amp via 9V battery or the enercell adapter 9V(dc) it makes a popping noise.. can anyone explaing that? regards, ryan
  - Suicidewafle
    
    That is simply a small burst of electricity moving through the speaker, and causing it to ‘work’. Like when you play music, but instead of a controlled signal it is just an uncontrolled current.
Michael Lewis

Looks like I’m going to answer my own posting: The author clearly intended to indicate by use of a triangular symbol that the LM 386 is the IC in the circuit. However, by adding the + and – signs to the input leads, he created the symbol of an op amp. This is a mistake that only a person with limited electronic knowledge would notice, since the square wave output of an op amp makes it clearly unusable as an audio amplifier.
- hollyjester
  
  I think you are incorrect, in that there should be + and – terminals on the schematic symbol
Scott W Vincent

Hauke, you need a log (audio) pot for audio signals. I don’t what exactly would be best for this circuit, but it seems that values between 10k and 50k are most common these days, though I’ve seen some amps that use 100k pots.
Scott W Vincent

That is very nice! I like how the lion artwork surrounds the speaker, looks great!
Fergal

Tim – Vocals are normally in the centre of a stereo recording. This means that they are present in exact same amounts on the left and right channels. Instruments tend to be placed more on one side than the other.

When making a mono speaker like this, the left and right signals get summed together. However, if at some stage during the construction, the polarity of either the left or the right channels is inverted, then anything in the centre, like the vocals, will get lost. This is because the vocals are now present as exact opposite signals on the left and right, and perfectly cancel out when summed.

This phenomenon doesn’t affect the instrumentation as they tend to be in different amounts on the left and right, and so do not cancel out when one side is subtracted from the other.

I can’t help you with regards the specifics of the circuit (I haven’t looked in detail at it yet), but a good place to start would be to look at the wiring of sockets and jacks – have you swapped a shield and a tip, for example?
Arnoldas Gribas

setup would be the same
yes it would be capable powering a bit more powerful driver, but don’t expect much because its only 1W
Arnoldas Gribas

very nicely done :)
distortion is boosted by increasing gain?
Hauke

i made a stereo version because i had enough parts left: https://www.dropbox.com/s/fqv7p5zpogspep2/lm386-stereo.jpg
- Pete
  
  Is there a schematic for the stero circui? I built the mono curcuit and am building a second but I dont know how to connect the two for stereo.
  - Zorro
    
    build two circuits. stereo line in has ground, right and left channel. use ground for both and left for one circuit and right for the other. the original version has left and right together in one circuit.
    - Pete
      
      Awesome. Worked great. My only issue is that the volume is half as loud in one speaker. I swapped speakers ad determined it is the circuit. Any immediate ideas. I’m assuming it is my craftsmanship to blame. I’ll probably have to make a new circuit.
  - Havok
    
    Really want to build a stereo Do this :
    Make 2 monoboxes In each, connect only one channel (left or right) of the input jack directly to the amplifier circuit board, and use a SPST switch to connect or disconnect the other channel, so each box has its own mono (or 1-channel) selector switch.
    
    Set both boxes to 1-channel, then use a stereo headphone splitter to connect both MonoBoxes to your music player.
    (I got this from the down of the article!)
    - jacob
      
      i was wondering if you could get a picture of this im starting out in electronics and such and i was wondering if you could upload a diagram on how to make the mono amp into a stero amp.
Scott W Vincent

Very nice! The pot is a great addition. I’m thinking of doing another some day with an option for line in level sources with a volume control.
Scott W Vincent

That’s interesting – thanks for sharing. I might try the 1 watt chip on my next build.
Ross Hershberger

Check your email inbox.
Jakub Czarnecki

I would say check that there is no short and make sure the chip is not in upside down
Hauke

yes
Ross Hershberger

I’ve checked with Parts Express and they have the $0.98 oval speaker tha twe used in some of the prototypes still in stock.
Ross Hershberger

Capacitor voltages are not critical, as long as they are at least 50% higher than the power supply that you’re using.
Ross Hershberger

The bass boost in the circuit can exceed the voltage swing capability of the amplifier. If you get distortion on bassy music consider using the EQ on your music player to turn the bass down. Or refer to the article and disable/remove the bass boost parts.
Ross Hershberger

We found in testing that some portable headphone players delivered a lot of noise when loaded with a high impedance. They need a lot of current drawn to shunt out and damp the high frequency hash in particular. That’s why the 100 Ohm input resistor. Terminating the headphone output with a higher resistance will result in higher noise on some source devices.
Ross Hershberger

Builder’s issues solved via email. He built it right, but had the worng IC chip. See his further comments below.
- rkan665
  
  can you help me?
Alec Spicer

I soldered, drilled the box, and the whole nine yards. I finally hooked up the power to see if it works but there is no audio. All I’m getting is a little bit of noise when I hook the power chord into the power jack. Ask me questions about the problem so I could give more detail and so I can get this awesome project to work.
- Jake T
  
  I’m having the same problem. I’ve double checked all my work but everything looks like it’s in place. The IC chip I bought the LM386N from radio shack. I don’t know if that might be a problem.
  - Havok
    
    Your IC might be upside down. (I think.)
praveen

I think its very helpful for me .
jerry

I want to have the option of my box being powered by a battery(in the box) and a wall plug. I know i’ve seen the instructuions here somewhere. can someone point me in the right direction?
- Hyrum Thomas Boston
  
  I actually did this with mine. I just with a simple solution of soldering a 9V adapter to the same positive and negative power leads on the power jack. This resulted in being able to use the power supply not only for a source of power but also for a charger for my rechargeable 9V battery. If you want to do this I would also recommend adding a power switch to the system so that it will charge better, instead of the amp chip using current sitting idle. You end up with a nice rechargeable amp that you can take anywhere. this is the link for the rechargeable battery I have: http://www.ebay.com/itm/New-9V-280mAh-Ni-MH-PP3-Rechargeable-Battery-/310406636702?pt=US_Rechargeable_Batteries&hash=item4845ad649e
Phil O

Awesome guide! I’m using a Nightfire Electronics LM386 kit I bought for $10 from Amazon. Saved me a little trouble assembling all the components. One comment on the circuit: looks like you bridged the input signals without resistors. I’ve read that this causes distortion and can even damage the source, because the two signals are essentially fighting to set “their” voltage on the same wire. It’s a good idea to run each signal through a 10k resistor before connecting them. But it seems that lots of people are following these instructions with no complaints, so maybe it’s not that important?
Pete

i did it. Awesome. powerful
gary green

Where Can I add a pot so I can have volume control?
- jeromymurphy
  
  Can you just use the volume control on your mp3 player?
- Zorro
  
  Ad pot at audio line in.
jeromymurphy

I had a great time building this. Great project for an amateur. My radio shack was sold out of the 8 pin connector so I used a 14 pin instead. Same cost, I just had to be careful what I plugged into and soldered. I used a speaker driver scavenged from an old Samsung surround sound. The speaker was flush with the face of the box so I used the metal lid from a canning jar with fabric glued in to finish it out.
Havok

Is it necessary to use an ic pc board? Reply!
bonsai171

Can this be modified to make a preamp and drive an amp instead? How hard would that be?
Havok

Hi in the schematic there are two triangles pointing down so, i am a newbie to this and schematics. so can you help me?
- bonsai171
  
  Those two arrows are ground connections.
  - Havok
    
    Thanks bonsai171, But there is only one positive connection.
    - bonsai171
      
      Ground is negative
      - Havok
        
        But there are 2 ground connections and 1 positive connections.Right?
bigredlevy

I made a veroboard layout:
http://2.bp.blogspot.com/-NnoOf5NSBOU/UXzBR6jy68I/AAAAAAAAAVQ/-4bTuU2QCM4/s1600/MAKE+Monobox+(2).jpg

my build:
http://levysounddesign.blogspot.com.au/2013/04/make-monobox-trash-speaker.html
Havok

Thanks bonsai171, But there is only one positive connection.
Havok

Hey, Ross there are 5 caps in the photos but in schematic there are 4 caps. But how?
- Pete
  
  Two of the caps “stack” together to get a higher value.
Havok

Thanks, Pete that helped a lot.
SkipF

I found an electronic crossover PCB via ebay in china…And I’m using a pair
of aluminum 2 way speakers; each speaker has it’s own amp. Power is a bit
funky. 2 18650 lithium batteries for the power, plus 2 14500 LBatteries for the
negative supply of the Xover.
Havok

Is it necessary to use an ic pc board?
SkipF

No… but it’s a whole lot easier. I used to build prototype cameras @Polaroid. Once we
got BOARDS, they worked a lot better than the WWrap or P2Point vector boards we originally
modeled the circuits with. 2 boards for $13.00…
Tommy

This is a cool project. I actually used a circuit similar to this to build a guitar amplifier into a cigar box (same workhorse LM386 and all). Only difference is that you would use a pot to control the gain. For any guitar players out there, you can very easily modify this exact same build (just sub out a couple of parts) to get a sweet-looking portable guitar amp. The following link shows the schematic (though it’s not my site or my work).

https://lh3.googleusercontent.com/-X8sUApMtOhM/UNEB4o8zwOI/AAAAAAAAArY/oQHvUsvDA2U/w500/amp-diagram.png
- Acacia460
  
  What speaker do you use? In terms of specs what works best for guitar?
- bjarnen96
  
  Is there any more information on this, or just the picture? I wasn’t sure about a few of the connections as well- specifically, if the wires were crossing over each other or actually connected in and around the chip socket. Thanks.
  - Tommy
    
    There is an instructable for the Little Gem at http://www.instructables.com/id/The-Little-Gem-Mini-Amplifier-Guitar-Amp-/. Between their schematic, and the image I posted above, things should come together nicely.
    
    The main difference between this schematic, and the one listed in this article, is that you have an extra potentiometer to control the gain (a must have with a guitar amp). I generally build my cigar box amps with a 1/4″ jack for a guitar input, and a 3.5mm jack for an iPod input. It’s nice to have something that you can play anything on. I’ve built about a dozen of these things, and I can’t say enough about them. This entire project can be assembled from RadioShack components for around $30-$35. I’ve also used allelectronics.com in the past in order to source cheaper parts (including a speaker).
    
    For my speaker, I went a little overkill and used a ~40-50 watt rated mid-range woofer. I was able to find one of these for about $5 (though allelectronics is listing something similar at $9 http://www.allelectronics.com/make-a-store/item/GW-2048/4-40W-SHIELDED-WOOFER-8-OHM/1.html). This is a much better speaker than you need in order to build out the project, but I liked my speaker so much that I ended up putting the same speaker into all of my designs.
    
    Please let me know if you have any questions!
    
    -T
Doug

I used a pvc pipe to house everything! its great
Havok

Can i use a 4 0hm 100watt speaker driver? Will it run on a 9 volt battery ?
Mark Stephenson (@MarkAStephenson)

My speaker is making a cracking/buzzing noise when played at all loud.
Organell

Is it really a good idea to short the left and right channels at the input jack? I don’t know about the output impedance of a typical phone/computer/mp3player but very few sources are really happy about outputs being shorted
- Phil Oertel
  
  I agree, it’s not a good idea to short them. Pass each through a 10k resistor before shorting.
  - Dave Jones
    
    Did you try this yet? I’m getting a lot of buzzing from my speaker even with no input (just power). I’m wondering if the resistors here will fix that…
maker mike

I think I noticed a typo in the magzine article… it says to run the off-board wwire from 4E to the outer tab of the audio input jack and from 5E to theleft and right tabs. This online article has the wires switched. I don’t want to short anything. Do any of the success stories have advice? Thanks in advance!
aktive0

i’m experiencing clipping/buzzing at 50% volume while sourcing from phone or laptop. is there anything that can be done? is this why people are recommending to add resistors before shorting? how exactly would i do that?
- Novaorbitdragon
  
  Did you use a 10kohm resistor
Jacob Stork

How can I fix this so that at high volumes the sound does not begin to distort and get fuzzy? I’m using 6×9 car speakers and I created two circuits and connected them together to make true stereo sound. Any thoughts or ideas on how I can fix this?
- Novaorbitdragon
  
  I’m getting the same sound
lasko

Will it work with a 3 Ohm speaker?
Acacia460

I’m building this today, but I wanted to make a modification or two. The problem is I’m an electronics noob. Someone mentioned that a way to add a volume pot would be to put it at the audio input, but there are two audio inputs, so how would that work? Would it make sense to add the volume pot after pin 5?

Also, someone mentioned current is an issue with low current if running from a battery. Could that be fixed by having several batteries in parallel?
Mike

I would like to try and add a rechargable battery and integrated charger into this circuit. Has anyone tried this?
Travis

How do you make a monobox for a subwoofer
jpeck

i built the box and it works. but i tried to substitute the stereo 1/8 jack with a mono 1/4 jack to play guitar through it and get nothing. anybody know what i’d need to do to get a guitar working with this design?
Rex

Can 1/4 watt resistors be substituted for the ones that are supposed to be 1/8 watt?
Jen

Cool. But what I want to do is take my dad’s old wood bookshelf speaker and power it with a micro usb rechargable power supply. Do I have to add an amplifier? I could leave it plugged in at home or charge it for on the go. Then I want to add an a2dp bluetooth ( via a a2dp headset?it has a 3.5 jack) and have my own little version of a portable sonos streaming device on my departed Dads old bookshelf speakers. This http://www.youtube.com/watch?v=XQ-vaNTqIPM and and your homemade portable speakers got me thinking. I have 2 of them and they’re great speakers. Since I have 2 stereo would be nice. Any ideas on how I would go about this? Thanks, any ideas I could get, I’d love to make this.
Jen

Found this,http://www.youtube.com/watch?v=tFGhPUzCirM but not a micro usb or rechargeable power supply.
aosetnuh

Volume and Bass/Trebble Control:
http://www-inst.eecs.berkeley.edu/~ee40/fa04/labs/acdc/EE40FinalProject-Part2.pdf
aktive0

Upcycle your old food tubs to make awesome sounding speaker cabinets!: http://www.youtube.com/watch?v=ZfIhq6xhRJE
Marco

Hi all,
I live outside the USA, and I’m a beginner, how can I replace this PCB with something else that I can easily find?
Thanks!
Nemanja

hi, can you give schematic with tweeter aded?
Vishal

I had follow exactly the same circuit and with almost same parts….i am getting a good amplified sound…but the problem is that when the 3.5jack is fully inside the phone (audio source) bass comes but the sound is very low, and when i plug out half of the 3.5jack in the phone a high sound comes but no bass also it is a little bit disturbing in high volume….

So what to do?? How to make clear loud sound with bass, as we listen in speakers that we bought from market….

plzz mail : [email protected]
Charlie

I just built this amp but I have the PCB hard-wired to the audio cable wires. It only works when the audio plug is pushed into my source half way. Push it all the way into the jack and no sound. Is this because the shield in the audio cable is really the ground, and both wires in the audio cable carry signal?
Charlie

My mono-box works great with my ipod, but I get no audio from my computer or radio. I’m happy that it is working great with the ipod. I tried 10k resistors on the source leads as suggested in a few of these posts and then I got no audio from my ipod too. I am back listening to my ipod with NO resistors on the leads. Go figure.
kc2dqp

Ross- love the build. HAD a lot of fun with it.

2 questions though-

1. do you have the part number for the PE speaker you used for this build?
and
2. How would one go about setting up a solar panel power back up in this build? I got a 9v panel on clearance when I was getting the parts..
- Hyrum
  
  I know the answer to your 2nd question. As he said in the description on step 13 “Your power source needs at least 300mA of current capacity. Voltage as low as 6V works for driving 4Ω speakers, but 12V is best for 16Ω speakers, so 9V is a good compromise.” So as long as the panel is at least 300mA it should work fine.
Charlie

Here is a short non-professional video of my MonoBox with a Maker Shed Color Organ Triple Deluxe II kit installed on top. The effect is cool.
Travis

What wattage can this unit produce at 8 ohms? Also how many volts will work above 9? I was told this can handle 12?
Jae

Hello. Just finished building the circuit. Checked everything and seems fine. Only thing is at around 70% volume on the ipod it distorts a lot (seems like the bass and even higher frequencies) I read the message that had similar issues but there was no reply.
I used a 1000uf cap that was recommended since my driver is 4 ohm. The frequency range (of the driver) is from way below 150Hz (50Hz) and goes to 22K. Another thing is the volume isn’t as loud as I had imagined. I would guess that 90db is pretty loud but to me the circuit seems too low in output. Used the LM386 chip. Any ways to trouble shoot this?
Hyrum

You said that it could be used with 16 ohm drivers. I have two 8 ohm 5″ drivers that are exactly the same. Could I use them in series?
- Travis
  
  Absolutely. Series will raise the ohms and parallel will lower it.
Niggamp

Hey! I’am a beginner to electronics. And i really want to try this out. So can you hook me up a easier schematic. I’am only 11 years old
Niggamp

Forgot to mention, if possible, Can you guys make a animation. (Anything is fine!). i’am not that beginner i made lots of complicated projects.
ALRUI

Heres a link to the schematic (its in the “project steps” #15 above)

http://makezine.com/projects/make-34/monobox-powered-speaker-2/

Keep at it, refreshing to see young people experimenting & using their hands to make things!
- Niggamp
  
  I asked for a Easier schematic or animation.. Well i already saw that! BTW Thanks!
  - ALRUI
    
    Thats what a schematic is & to my knowledge there isnt an “easier” way to show the circuit. What part about it are you having trouble with?
    - Niggamp
      
      It is very confusing to me. Especially when building in a perf board. And those power supply thing. LOL.
      - ALRUI
        
        Just think of it as a roadmap and follow the lines (wires).
Niggamp

Hey! ALRUI could you make a easier schematic for me? may be something like this:amazonaws.com/files.digication.com/M1fe471f05d04ba6c141449d65990ade3.jpg.

Thanks in advance!
- ALRUI
  
  The link is bad
  - Niggamp
    
    Try this :http://letsmakerobots.com/files/userpics/u18084/mouseyCircuitColor_FINAL.png
    - ALRUI
      
      Its the same concept just not in color and not with pictures of the components:-) The R’s are resistors, the C’s are capacitors, U1 is the amp chip, etc.
ALRUI

Any speaker experts out there? I have a nice 4″ Pioneer but its 4 Ohm. Not sure how it will work with the circuit seeing the specs state 6-12 ohm yet mentions changing C3 if using 4 ohm.
Luckymat

How many W has this speaker? And hot to increase power?
Harnon

Hello,
I have 2 speakers, 8 W – 6 Ohms each written on.
1) Does they match for this project ? Any mods to do for it ?
2) For doing the stereo , should it be necessary 2 separate power sources or is it possible to use one and share it ? If yes, how ?
Thanks for advice !
- ALRUI
  
  You would be fine with that since the LM386-4 is 1 watt output, also the one power source would be sufficent for powering 2 of these circuits.
  - Harnon
    
    Thanks for quick and kind reply.
    Soldering iron will be warming this WE…
robertfarrand

Is it possible to add something like this:
http://www.ebay.co.uk/itm/Rechargeable-Battery-For-CE-RoHS-Apple-MA005LL-A-400mAh-Li-pl-/300903003229?pt=UK_MP3_Player_Accessories_Batteries&hash=item460f37745d

How could you add this to make the speaker rechargeable?

Also where can you add a switch in the wiring to turn off completely even if a battery is still connected to stop killing the battery?
- ALRUI
  
  As for the battery rechargeable would be great but the problem is you would need a charging circuit or a quality external LiPo charger as LiPo batteries are extremely dangerous (explosion/fire hazard) when not properly charged! As for the switch just put a toggle switch in the – (black) line to break the circuit between the battery and ground.
Novaorbitdragon

Could I use a 4kohm resistor instead of a 10kohm for a 4ohm speaker
Hyrum Thomas Boston

Great project, I had a lot of fun making this. I have one problem though. If I wanted to use 5 smaller speakers instead of one big one, should I wire them in parallel or series? They are 4 ohm and 25 watt.
gbelectronics

This wouldn’t work in britain would it
soldes longchamps

Hot website uncovers the critical info on the gucci and also the reasons you have to take action straight away. soldes longchamps http://www.rep-search.com/
googolplex

If I wanted to make a stereo box, would I need twice the voltage to power the two drivers and the two LM386 chips?
- ALRUI
  
  The voltage will remain the same, when you add more complexity to the circuit the only issue would be current draw but in this case youll be fine.
  - googolplex
    
    Thanks a lot!
Alasdair

Hi I was wondering what the output wattage of the MonoBox is? I am interested in building it but not sure if it will be loud enough. Thanks.
- ALRUI
  
  It depends on which version of the LM386 chip you get is. According to the National Semiconductor data sheet for said chip the wattage is as follows:
  
  LM386N-1 0.325 watts, LM386N-3 0.7 watts, LM386N-4 1.0 watts
  
  I got the -4, with a small speaker in a small enclosed box it will be fairly loud given its size.
Lah

what about 12V amplifier? would it be the same?
Andreas Landoy

If I want two speakers in my box, do I have to make two circuit boards?
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Havok

Guys!, I thought i’d build this as it was useful for me. After looking at the schematic i found it confusing. So, Can any of you give me a ‘ready to transfer’ PCB layout. Any help would be appreciated. Thanks!
Havok

Could you guys give me a ready to transfer pcb layout.Thanks!
Havok

Could you guys give me a ready to transfer pcb layout.Thanks! Please, need it urgent. Need it by 1 week.
Garnet

Just finished my first mono box. I am getting sound that is very distorted and not loud. Does anyone have a suggestion to what is causing the distortion?
Steve

I am having the same problem as others – that after 50% volume I start to get distortion. I have played with capacitor values and that has helped some but no way do I get full volume without some distortion. Is there a fix or modification?
- ALRUI
  
  How many are having this issue, Im curious before I start my build.
- ALRUI
  
  Curious as to what vendors LM386 you guys are using as well as the dash # which designates power output of the devise.
- Charlie
  
  It might, just guessing here, have to do with the source. I noticed my iPod shuffle can play very loud and sound great, while my Android phone has distortion at higher volumes. I am going to try a headphone amplifier to see if it clears up the distortion from other devices.
glory0712

Can somebody help me get the amplifier circuit board? i don’t know where i can get the right one…they don’t have it at radio shark…if anyone knows a website where i can get the right,
- [email protected]
  
  Radio shack has them back in stock as of today (at least online) also mcr has them.
  - [email protected]
    
    Sorry typo MCM Electronics
Eleeg

On the schematic, pins 7 and 8 aren’t connected to anything. does this just mean they’re not being used?
Joey

The “parts” description tells about 3 or 4 different capacitor and resistor but in the video they use just a couple… how’s that??
- ALRUI
  
  In the text is a description of the options for a couple of the caps/resistors, likely the video shows the defaults only.
- ALRUI
  
  Anyone finished one of these up and posted results on YouTube?
Joey

Radioshack doesn’t ship to Europe… right? How can I do??
Charlie

My mono powered speaker box works beautifully, if I plug in an iPhone or iPod. Any other source, i.e. computer, non-iPhone, radio, record player (with headphone jack) does not play any music. No sound at all. Why would this work with Apple headphone jacks and not work with non-Apple headphone jacks? This is confusing and a little bit annoying. Any ideas out there? Thanks.
- ALRUI
  
  Hmm Im curious about this as well as Id like to plug in iPhone & guitar (through separate jacks). Anyone have an answer to this one?
- Charlie
  
  Not sure yet what happened, but I built two new amplifiers and they both work with all music sources, but, as in Animal Farm, not all sources are created equal. The iPod and iPhone have the strongest and almost distortion free signal that amplifies quite loudly. I’m really pleased. The other sources (portable radio, PC, and Android phone) all amplify but the signals are not as clear or strong (and give distortion at loud volumes). I am going to try a headphone amplifier to see if I can reach a state of happiness with every source signal. My original problem may have had multiple causes i.e. dirty jacks, not having volumes turned up enough, or a fluke in my construction (I’ll have to check this out when I get the boxes back from their recipients). I’ll post again if I come up with a definite cause.
  - ALRUI
    
    Did you give some as gifts? Cool idea!
    - Charlie
      
      I gave one to each grandson. I added the Maker Shed color organ kit (see my post earlier with the short youtube video).
Landon

Could this be made into a WIFI system by plugging the headphone jack into a WIFI enabled raspberry pi? Im curious about the power supply. Would this system work if the rasp was powered by a 5V micro usb?
Great DIY by the way, very clear and understandable.
Vesko

I made it but if the bass is too much it starts to crackle please help
- ALRUI
  
  What speaker did you use as it probably cant handle to low freq’s well without distortion. Also try to adjust the bass/treble on your input device (iPhone, etc.).
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JKLauderdale

This is an awesome project, I’m going to try squeezing a USB charging battery in there as well so the speaker becomes a backup charger for the phone/tablet.
- Chris Mitchell
  
  Plz let me know how it works out. I want to do the same
  - JKLauderdale
    
    Worked beautifully – I’m adding NFC charging to it, I’m wondering how many hours I can get from my little 10K USB battery to keep my 920 at full while streaming and playing at ~40% vol
kraw

I was going to add a small bluetooth receiver in there. I am new to this, so I was going to power it separately with a second 9v battery connected to a usb hub through a 5v regulator. I know this might sound like a dumb question, but what would be the best way to go about powering the speaker and the bluetooth receiver from the same source?
bailey

I just made this project to the tee using the instructions here and I cannot get sound to come through my speaker. All I get is crappy distortion. Can someone help me please?
- Chris Mitchell
  
  Are u sure u did everything right? Mean works great.
- Stevie Russell
  
  check for a bridged solder maybe?
- Stevie Russell
  
  really check your work! i was actually satisfied with how mine sounded and then i noticed the input was soldered on the wrong holes. oops. the quality is actually pretty much the same with it corrected though.
raybatesosj

These Kinivo portable speakers are my favs – http://www.amazon.com/dp/B004HHICKC/?&tag=431-20&ie=UTF8 can play excellent quality sound. They are overall very easy to use. The price is right and they are great for travel.
Marcos Rivera

Just put this all together and i’m getting really bad sound quality. its all distorted
Chris Mitchell

Just made the amp chip, it works well until I put my volume close to max, then it gets lots of distortion. I made a boom box backpack, I’ll post pics soon enough, sounds great so fa. This was my first soldering project BTW.
Chris Mitchell

I fixed the distortion problem. It was simple. I wasnt getting enough power to the speakers. I had 2 speakers hooked up but only one 9v battery. I ran two 9v batteries in parallel and it solved the problem. God they sound better than headphones and it truly does rock.
Guest

Can i request for the circuit diagram, please? Thank you.
- Andres
  
  its on the step 15
Andres

my local electronics store dont have the 470uF- 35v, can i use a 470uF-25v or 470uF-50v or a 500uF-35v?
- Andrew Terranova
  
  Stick with the correct capacitance valve and the higher voltage range.
Jordan Wong

I’m making a similar speaker to this using the same circuit for a school project, and I want to have two speakers instead so how would I connect the two speakers into the circuit?
- Jim Campbell
  
  Having made one similar to this, build 2 circuits, and route your left & right inputs to the separate chips. They are small DIP8 packages, so you could use a single DIP16 or 18 socket. I used an 18 pin socket, so I would have a 1 pin space between them.
paul

Hello i would like to do this potable speaker but can the amplifier hold up 2 speakers and can i put a wall adapter?
Stevie Russell

Great for beginners who don’t know how to wire something from a schematic. Can anyone tell me if i can just wire up a battery snap instead of the power jack? Also can i just wire a 3.5mm plug in place of the audio input jack?
- Jim Campbell
  
  Yes, and yes.
mikerogerswsm

I made a similar unit using a TDA7052, this runs on a lower supply voltage and has good power output. I used a 9V battery and mounted it in a cheap plastic food box. Very useful in conjunction with my portable movie player and to amplify mp3 or youtube sound from my tablet.
cb

can anyone offer any tips on how to add a potentiometer to the box?
Noah Hunt

Okay I have built this amp over 2 TIMES AND I AM SICK and tired of it not producing sound or very low sound. I seem to be doing everything right, starting to frustrate me I don’t feel like BUILDING a whole new one, I seriously need helP IF anybody could help me, that would be great e-mail me at [email protected]. Can anybody look at a picture and tell me if I’m doing it right if I show showed one.?
ryan d

here some tips in removing distortion,add a bigger value of decoupling capacitor instead of 100uf cap,this will help to filter more noise coming to power source
Ahmad Joor

i built one and its my first !
but the LM386 cracked when i connected it to the power
- ryan d
  
  maybe your ic did not resist the voltage that you connect,how many volts did you put on your circuit
  - Ahmad Joor
    
    A battery with a 12 v
sylvo

i live in Australia and radioshack don’t post to here and they are the only place i could find that sells the required parts, if you know of anywhere i could get most/all of this stuff that would be great!
ryan d

if the circuit does not work right,just check your work step by step,check the polarity of the ic,check the signal input,check the loose wire connection,check if there are solder bridges,and last check the power supply,it is best if you put an LM7809 voltage regulator to filter out unwanted noise coming from the power
source
ryan d

for those who strating with electronics,you can built it in the board of your choice,like perfboard,just follow the connection on the scheme.
ryan d

i think this bass-treble control schematic can be apply on the circuit
ron jacob

Nice HowTo, BUT the LM386 is not made for high power output or very loud
sound (max ~0.1W) Please be fair enough to tell the people that they will a lot of
distortion with that if they really want a monobox for outside music.
One may consider the LM383 instead.
- EarlGreyParty
  
  The LM386’s output power ranges from 0.3W (LM386-1) to 1W (LM386-4). Still not earth-rattling, but certainly enough for personal listening. And the LM383 was discontinued over ten years ago.
Andres

How could I make a stereo speaker without building two separate Monoboxes?
Andres

I made one monobox and i only got sound from the right channel so i made another one and it has the same problem. please help.
david

guys, please help me!!! The instruction is not on the website anymore!!!
William Lee

Wonder if anyone is still listening…

I have a whole bunch of drivers with a drivers with a resonance of 191 Hz and a sensitivity of 83 dB. circuit works but very bassy and distorted when turned up high. Any help on modifying the circuit?
Colin Parker

Can a bass/ treble be added to this circuit or anyone know where there is a schematic
Sanket

Can U Plz Post The Circuit Diagram for doing it on own perf board
R Muhammad Farhan

does anyone have the schematic of this project?
Paulo Henrique

Can I use a car speaker?
Philip Taht

Great project.
Just a comment on the suggestion in the article about tightly sealing the box. Certainly I would endorse this tip where the speaker is in the lid. However, consider this for a modification: In a tightly sealed box the movement of the speaker will be severely restricted. As the cone moves back it meets a great deal of resistance against the air trapped in the box. If there was a vent in the rear of the box the compressed air would be vented through the vent. The benefit obviously is that the speaker cone is free to vibrate more faithfully representing the varying voltage it is receiving. Also the venting of the air (=soundwaves) will give the impression of spaciousness as the out of phase waves bounce off the wall behind the box. There will be a less constricted feel to the audio. Experiment with the size of the vent; it doesn’t have to be a big gaping hole. Try bringing a small flame from say a cigarette lighter near the vent and see it vibrate.

Just a thought.
the way of the future

I have a pair of bare 3W speakers and I have never installed speakers before, can you recommend a reference for how to install them? The loudness seems to be very sensitive to how I hold the speaker so I imagine there is something to doing this right. Thanks.
Greg

Lessons Learned: Use a magnifying glass to identify any connections that may have mistakenly bridged. I had a very low signal coming from the speaker and determined that my problem was in fact a tiny trace of conjoined solder traces.

Now once I figure out why my 9v 200mA wall adapter won’t work I will update this.

Cool project though thanks for sharing.
Ayoub Gharbi

how to make amplifier
for system speaker :
6 ohm
300w max (programme)
50-20000 hz
87db/w (1m)

I have a device that : Muusikakeskus LG Extreme Dynamic Sound System FFH-8970
Stefan Zdravkovic

Can i use power source of 9v/1A?
Kumud

How can we modify the speakers to increase the output by 5-10 dB?

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