Introduction: Portable Amplifier

Picture of Portable Amplifier

So you're trudging through the woods, just you, your guitar, and your amplifier. Suddenly, a large bear approaches and you have no option but to shred him with your insane guitar skills! (running is not an option, as everybody knows that you never run from a bear, you fight him)

Unfortunately, there are no power outlets within sight! Steeling yourself for your grisly demise, you try to play a song acoustically.. but it's not loud enough. As the bear reaches over you with his jaws, you wake up. And are aware of the need for a portable amp. But, since you are a musician, you are obviously at poverty level and can't afford a small portable amp. So what do you do? You build one, for free of course, out of everyday parts.

Step 1: Collect Your Materials.

Picture of Collect Your Materials.

For this project, we will actually be using an Ibanez bass amp, and a bass guitar (my electric guitar isn't in yet, and the amp is obviously far too big to be portable, and this was just laying around).

Also, please keep in mind that this is a simple proof of concept project (proof for myself), and is in no way safe, complete, stable, smart, etc.

Basically, what we are going to do, is take this combo amp, and run it off some batteries, to make it portable. Why? Read the intro ;)

So what you need (and you should be able to find this anywhere in your house, friend's house, roommates gym bag, etc.)

2x9v batteries
2x9v battery clips
Wire (thicker is better, try 10awg)
Alligator clips (preferably 4)
Switch (SPDT)
Duct tape

Step 2: Wiring Things Up.

Picture of Wiring Things Up.

Once you've collected all your materials, go ahead and dismantle your entire amp. There are lots of screws, if you don't know which ones need to come out, take them all out. Just make sure you keep them separate, so you can put it back together later if you so choose.

Now, this amp in particular, takes a 120V current from the houseline, and steps it down to 13v for use with the amp. However, I am lazy, and don't really care what happens to this amp, so we're just going to completely bypass the stepdown converter, and hook up a sheer 18v directly to the mainboard. It's all solid state, so the worst that'll happen is a battery might explode, or you'll burn out the ICs. Hope you don't want this amp anymore.

So, basically, what we'll do, is wire the two batteries in a series, attach the negative to the mainboard, and the positive to a switch (because we're bypassing the built in switch). And that's pretty much it, as far as wiring goes. To wire two batteries in a series, attach one positive terminal to the other's negative, and then use the free positive and negative terminals to attach to your actual destination. I find that the little 9v battery clips are the easiest way to do them, although I could only find one of them when I did this project.

Step 3: Stick It All in There.

Picture of Stick It All in There.

Now that you've hopefully gotten it all wired up, turn it on and give it a test run. Due to the increase in voltage, you'll have a nice little distortion effect. If you have everything working correctly (the little blue LED in the front turns on for me), then go ahead and stick it all in the case (or build your own!).

That paper towel is down there only to insulate the connections from touching the case and shorting out. Totally optional, if you're good at insulating your connections individually. Obviously secure everything with duct tape, and jam it all in there, making sure to reconnect the speaker.

Step 4: Go Shred!

Picture of Go Shred!

Now that you have it all back together, attach a strap, or a belt clip, or a belt, and take it out and show your majesty over all things with ears!

Congratulations! Now, make it better. Because this is just a quick, 20 minute project that I threw together in my free time.

Some things to do better:

Either use exactly 13v in batteries, or get a stepdown converter.
Make it so that everything fits.
Use the built in switch.
Work on extending the battery life.

I have no idea how long the batteries last, but obviously don't expect to be playing any concerts or shows with this setup.


tehnoloog (author)2016-03-10

Use lighweight Li-Po batteries!

~15V (4S) Li-ion hobby battery plus charger start from €20.- in hobbyking.

These range from 1Ah to 20 Ah and can be heavily abused (DIY portable boombox or bass amplifier).

MarkTBSc (author)2014-11-26

To be honest, I'm amazed two PP3 batteries would power this amp at all! The standard Alkaline model is specc'd with about 500mAh capacity and they're designed to discharge over 20 hours, giving you 25mA draw. At 18v that's almost 0.5 watts for the whole system. If you try and draw at 100mA then you'll get maybe 1 hour out of the batteries and they'll be burning hot. Even that will only get you 1.8W. I'd switch over to 3 4.5v 4Ah Alkaline lantern batteries. Drawing at their rated current of 200mA, you'll have almost 2.5W to play with and the power will last for over 10 hours. Also they're not too heavy and you're not messing around with Lead-Acid or Lithium.

muddog15 (author)2014-04-09

Also. Little deer feeder batteries are light.

muddog15 (author)2014-04-09

12v battery works better. Or maybe a voltage regulator.

PCvsMac (author)2008-04-18

Hello again :) Something that has been confusing me: Would it simply not be easier to have, let's say a 12V Lead Acid battery (from a car, maybe) and simply strip a male computer cable (the end where it plugs into the power supply, which I believe in America is 2-prong 120V) and attach some alligator clips to it and plug the other end (when you want to plug your amp in) into the power feed of the amp?

finfan7 (author)PCvsMac2008-04-29

the problem there is weight. An amp can be very dense. (high weight to volume ratio) The same can be said for a car battery. So the weight of the car battery would easily double the weight and volume of the amp. That would not be conveniant.

PCvsMac (author)finfan72008-04-30

That is fair enough then. But would it still be possible? And how about using a really small car battery?

ElvenChild (author)PCvsMac2010-09-30

mac won again

ac1D (author)ElvenChild2011-01-26

You think?

ElvenChild (author)ac1D2011-01-26

I know

finfan7 (author)PCvsMac2008-05-01

It would work but I have never seen any small car batteries. I had a better idea though. I saw someone say somewhere that they had a circuit that would switch the power source to the next battery when the first one got too low. I thought it should be combined with a set of rechargable 12v camera batteries. Total price equal to a car battery but with longer battery life and no replacement costs within the near future.

rocketman221 (author)finfan72008-07-24

use a small sealed lead acid battery like what is used for backup power in an alarm system. I have some 12 volt 7AH batteries and they only weigh about 5 pounds.

PCvsMac (author)PCvsMac2008-04-18

Also, someone please reply! Thanks, I hope to hear from anyone soon!

ElvenChild (author)PCvsMac2010-09-30

it is still winning

ElvenChild (author)PCvsMac2010-09-30

mac won

cody316 (author)2010-09-16

Thanks to you, i can impress chicks ANYWHERE now! nice instructable dude, and ill thank you ahead of time in case i ever get into an encounter with a bear!

arcane2rox (author)2010-04-02

Legenary intro to the instuctable! I have to say that I am a musician along with several friends of mine and we are all at poverty.

northconnor (author)2009-12-21

Nice job. Does it go to 11?

scott! (author)2009-08-30

Dude, nice intro, that cheer'd me up! :D lol

RelaxedSoup (author)2009-08-06

Maybe you could try using rechargeable batteries, and when the amp is plugged in, have the batteries charge. Perhaps you could also make a bypass switch, that, when plugged in, will let you switch between charge and battery bypass... hmmm. My old 15 watt amp is 500 miles away, when I get it back I'm definitely going to try that. Also, nice instructable, if I had a nickle for every time I've had to fight off a bear with my guitar...

ironsmiter (author)2007-05-06

IMHO, 15 min isn't nearly long enough :-)
At most, those standard 9-volts are gonna give you 1200 mAh (for Lithium-Ion), more likely 560 mAh and that's not much. Rechargable Nicad "9-volt" batteries produce closer to 7.2 volt, putting you at 14V, with the added bonus of being rechargable... but with a lower total capacity(about 120 mAh) but that could be fixed by running in serial and parallel.
If the circuitry can run at 12 Volt... use a pair of 6volt lantern batteries.. or better still, a "sealed lead-acid" battery out of an old UPS, or new from the store...

"(a)add to the already heavy weight,"
yep, but 5 pounds for the 8Ah battery i found for $12

"(b) cost more than amp itself"
how cheap was that amp, and where can I get one? ;-)

"(c) most likely leak at some point."
Eventually, those 9-volt batteries are gonna leak too....
Modern sealed batteries have very little chance of leaking and can be safely used in any orientation...just don't cook them, or they'lll off gas and that's bad for your circuits.

"I've been meaning to look into some higher voltage batteries"
even with the 2x9volt.... you SHOULD try to use some kind of voltage/amperage regulation... even more so, with bigger, more expensive batteries...

Would make a FUN collaboration...
Here, I'll start :-)

And consider putting the batteries down, on the bottom of the case if the back panel is removable. it'll make it seem lighter, through better load balancing.

use a 12-volt rated switch(like the one you're using now :-) and mount it on the case... splice into the 13volt wires, sending one straight to the battery, and the other to the second battery terminal, by way of the switch(interrupts the circuit when "open") ...
Now, when it's plugged in, 13 volt goes to the amp as normal.... when the power goes out, you flip the switch, and presto... battery backup power.

If you get really funky, Remove the transformer completely...
in it's place, wire in a "battery tender"... and of course a battery.
Now, when it's plugged it, it runs off the combined might of the trickle charger and the battery... when it's OFF, but plugged in, the battery is charged/maintained at peak readiness... when It's unplugged, throw the switch to ON, and rock out!

Since it's all ICs... and I see what appears to be on-board voltage regulation, you could probably drive it with anything from 11.5 to 18 volt(at least that's what the ICs in my radio are rated at), and let the beastie take care of itself.

And for heavens sake, GET SOME ELECTRICAL TAPE! $1-2 a roll el-cheapo from the store is just fine... or, if you wanna get spiffy, a $5 bag of heat-shrink tubing from the local mothership... er, I mean Radioshack... or wherever. If you're gonna be hacking electrical stuff... electrical tape, and a soldering iron will be your friends :-)

tundrawolf (author)ironsmiter2009-07-30

The smallest amp I have is a Fender Eighty-Five. I was looking at the schematic, and the most DC voltage on the mainboard is 40 VDC. That'd take a minimum of 3 12v batteries to match-that's a lot of weight for an amp that is already kinda hefty.

ironsmiter (author)ironsmiter2007-05-06

dang.. posted too soon... Tower Hobbies has a 4.5Ah 12V Starter Battery and it's matching charger for about $10 a piece... would add a total of 5-6 pounds for both, plus the wiring...

uzerzero (author)ironsmiter2007-05-06

I'm gutting everything out of the inside that I won't need (120V input, voltage regulator) which lowers the weight quite a bit. I tested with a 12v wallwort, and it will run off 12v. So that battery and charger from tower hobby should work pretty well. However, I'm moving soon and really can't spend any money, but if somebody wants to donate a little bit, that would be great! As for the charger, I'm thinking of perhaps building a breakaway cable, and coiling it up inside the amp. Either that, or put everything, adapter and all, inside the amp, and run an extension cord. As for the price on the amp, I received it as a gift as part of a combo set. It's retail price runs at around $70 though. But you can find any number of similar amps for $30-$40. I underestimated on the price. Until I either muster up enough money to purchase that battery and charger, I'm just going to keep the 9V batteries in there for now. Makes a good conversation piece :)

uzerzero (author)ironsmiter2007-05-06

Thanks for the good tips man. I do use electrical tape 99% of the time, but I left my last roll on my windowsill, which rendered it completely useless. I'm republishing this to a collaboration, so any ideas for department stores that would carry any products, etc., would be great :) On another note, my guitar comes in this week. :)

jkoznek (author)2009-06-28

Check out . They have solar panels. I was thinking a 20v solar panel and some rechargeable 9v. I think I saw a 20v panel there 12" x 9". That could be used as a "back panel" to the amp with the circuit inside. You get the compact size and weight plus a renewable energy source. could go to goodwill and pick up some old computer speakers that are 9v and use a 3" x 9" 9v panel and a 1/8" to 1/4" plug converter to plug into your guitar... not as loud and won't be able to hold the same kind of bass but it would work w/out frying your amp :P

backcountry (author)2007-05-07

You want a really portable amp? Try one of these:

they look god awful

Khurs (author)backcountry2008-02-06

I bought one about a year back, they give off about 1.5w. They sound terrible, even with a quiet guitar

snotty (author)2008-03-30

Need more details for transformer pinouts. Can anyone point us to some general instructions for bypassing different kinds of transformers? That would be awesome! I really like this project but I'm having a hard time adapting it to my "RK 20rc Rocktek" amp. I want to put it on my bicycle for critical mass rides and maybe even make it pedal-powered later. -Yeah

Khurs (author)snotty2008-04-09

I just pulled mine out then linked the cables. This allows the switch to work and reduces the weight greatly

timgray (author)2008-04-08

It did save me from several bears, though

timgray (author)2008-04-08

I did a similar thing to my samick bass amp, and cooked it... So I checked the voltage on the back of the transformer and got 12 volts, sounds good right? I probly should have check to make sure it was 12v DC, It wasn't. It lasted a while but the sound quality and volume gradually deteriorated until I ended up with silence. Very sad but it was cool while it worked. Anyway I just built a new rig, perhaps I'll tell y'all about it later...

PCvsMac (author)2007-06-24

DUDE! I created my first Instructables! I have made myself a guitar amplifier out of spare parts, running from a 9V battery, and yes, it is portable. I am not sure if it works, but I think I am on track. Let me know if I have made any mistakes or recommendations, Visit it here.

pinkpooj (author)PCvsMac2008-02-23

You took it down...

PCvsMac (author)pinkpooj2008-02-24

Yeah, sorry about that. Apperently I needed to take it down as it did not contain pictures. Anyway, it was not a real isntructable and it did not work, so I removed it. I appologise for any inconvienice caused.

pinkpooj (author)2008-02-23

I have a Roland Micro Cube that runs on 6 AA's, or a cable. It lasts for about a week.

ipatch (author)2008-02-03

hey man just connect a car battery to an DC converter and plug it in its easier and lasts longer

shaunak (author)ipatch2008-02-04

A car battery supplies DC power.. why a converter? But really, those square batteries have a worse life than 1.5V D cells. Ps: you could also try Ni-cd batteries.

ipatch (author)shaunak2008-02-10

WOW my bad i ment an AC Inverter! Good Job Ian way to say the complete opposite... my bad...

LasVegas (author)2007-05-04

This had the potential of being a great instructable; Had you taken the time to experiment, refine the process (alternate battery choices) and present a finished project rather than the results of your first attempt. As it is, it's rather lacking.

uzerzero (author)LasVegas2007-05-04

Once I have some more time, and some more money, I will definitely put together a much more thorough instructable. I've been meaning to look into some higher voltage batteries, i.e. some camcorder ones, etc., especially since they are rechargeable. And those 9V batteries have lasted a good 15 or 20 minutes of testing so far. Perhaps this should be a collaboration.

Danny (author)uzerzero2008-01-14

Maybe buy some rechargable 9v's and add a solar panel on the top, im sure the bear will probably wanna play a harmony after u beat him and your battery can stay on solar power!

Metal4God (author)2007-07-19

this is useless if you have a half or triple stack

Danny (author)Metal4God2008-01-14

I feel this comment was to show you knew what a half stack is? congradulations.

You have vastly different requirements for portability than I then.

i dont half a half stack :-{ but i want to get a triple

wingman246 (author)2007-07-12

i have but thing to say... isn't usually the devil instead of a bear who you have to bust a massive maamajama for?

stevoIution (author)2007-05-05

If you were really keen you could use a car/motorbike battery.

uzerzero (author)stevoIution2007-05-05

I could. But (a) that would add to the already heavy weight, (b) cost more than amp itself (c) most likely leak at some point. 9V does me fairly well. If need be, I could even create a bank of batteries that will switch once one is depleted.

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