Combo Amp to Speaker Cabinet for Under $40

Introduction: Combo Amp to Speaker Cabinet for Under $40

About: I am King of the cheap guitar, I like to make stuff. I am not good at everything, but I am not afraid to try. I play bass, harmonica and guitar. I like to find great deals on music equipment. Something inex...

Since I am a musician on a budget, known to my friends as "King of the Cheap Guitar", when I needed a speaker cabinet for some of my amps, I did not buy one, I built one, well sort of. This project took patience to find what I was looking for, and then it took me a long time to get around to doing it. Once I started the whole process was about 3 hours, including cleaning and drying and fixing a torn speaker.

For this project you will need:

Dead Combo guitar amp (with good speakers)
Speaker wire
Plasti-dip spray (optional)
1/4 inch mono jack

Philips Screwdriver
Soldering iron and solder
soap and water

For the speaker repair you will need
Elmers glue (I used clear)
paper towel
Bamboo skewer

Step 1: Acquire the Combo

I got this idea to find a dead amp and use it as the shell for a speaker cabinet. An empty cabinet can cost upwards of $200, and this way I would already have the cabinet. I lucked out and on Craigslist found an old Peavey Amp with the amp part missing, but the shell and speakers were intact. I contacted the seller and bought it for $30. When I saw it, I knew I had just what I wanted. 

The amp was gone, but there were two 12" Scorpion speakers, so I not only had my speaker shell, I had speakers! In a previous life this box was a Peavey Stereo Chorus 212. On a side note, you can score these amps cheap because they are solid state, but let me tell you they are a great sounding amp. Clean headroom for days! Clean and chorusy, lots of fun for clean tone, and takes pedals well too. Check out this video

Step 2: Testing the Speakers

Once I got it home I used a shop vac to remove the dust elephants hiding inside, and dug up some wire to make a quick and dirty harness to test the speakers. Since I eventually wanted a 4 ohm load, and these speakers are 8 ohms each, I wired them in parallell. Read about speaker wiring here It is important to match the impedance of your cabinet to your amplifier, if you do not want to possibly fry your precious tube amp. Solid state is much more forgiving.

I used 12 gauge 2 conductor jacketed speaker wire, because I had it on hand already. The Scorpions sounded good and I was really digging the sound, when I heard something funny and realized there was a tear in one cone. Before the project went further a repair was in order.You can buy replacement baskets for the Scorpions, one thing really cool about them. But the basket was almost the same price as an entire speaker ($80) So quick side trip:

Step 3: Break to Repair the Speaker

Removed the speaker, used canned air to blow all the dust off and examined the tear. Since it was not too big, less than an inch I chose not to replace the cone. I used single ply paper towel and tore a piece a little larger than the tear, soaked it in clear Elmer's glue and then using the blunt end of a wooden skewer, carefully worked it into place. Did the same on the back for good measure. Let it dry about an hour while I did other things. I did not take pictures of these steps, but here is the repaired speaker. Normally I would lightly spray paint, or use a sharpie to color the repair black, but t his cone is well, not black.

Tested it and it sounds fine. Back to the main project

Step 4: Take It Apart and Clean It

Removed the speaker cover, and then removed the four screws holding the speakers to the baffle (I used a small tupperware container to hold screws and parts. Helps keep me from loosing them. Stick a magnet in the bottom and steel and iron parts stay put).
Removed the upper back cover where the amp would have been and the lower. And removed the crappy casters that were on it. They were about 1 1/2 inch, and stuck on everything. Hit her with the shop vac and and then warm water and a dishcloth. Not trying to make it look perfect, just removing the major dust and nastiness. This had probably been sitting in a storage locker for a long time. Notice that the speakers don't perfectly match. This means one was replaced at some point.

I used Plasti Dip spray to cover some holes in the Tolex covering, and also to coat inside the case and reduce any rattling. In theory at least. This product dries to a matte finish so what the heck.

Step 5: Wiring and Re-assembly

Now that the speaker is repaired and the shell cleaned, time to put it back together. I used part of my test wiring harness since it iwas already wired in parallel, and the speaker lugs were on it. I used a leftover project box from Radio Shack, Drilled two holes in it and put a new 1/4 inch mono jack, and ran the wire out a hole in the back of the box. The box is hot glued and screwed to the top of the amp using some screws I found in the shell during dis-assembly and clean up. I used some wire management clips I had leftover from another project and screwed those directly to the case to keep the wires out of the way, and neater. I could have painted the wire jacket black, but I wanted to finish it and ROCK!

I left it open back, since it is mainly for guitar, I am considering making a piece of ply to cover the openings left in the back to see how it sounds both ways. Eventually I want to order different grill cloth and make the speaker cover, well cover the whole thing.

Step 6: Plug It in and ROCK!

Right before I finished, I decided to black out the orignal logo and shiny chrome sides. I used the plasti dip spray, if I want to I can just peel it off and it is back to shiny. 

I plugged in my Trusty Epiphone Valve Jr. Head and warmed up the tubes, and let her rip. Like all Scorpion speakers, these break up pretty nicely at mid volume. And yet I could play cleanly too and get a nice sound. Since this amp has no eq, only a gain control you really get the sound of the speakers and the guitar.

Next I grabbed the reason I wanted this cabinet so bad, my 1967 Fender Bassman! Since the output on the Bassman is 4 Ohms,  I wired this for 4 ohms. Most cabs are wired for 8 ohms, or 4 if you stack them. The amp sounds great, breaks up and distorts nicely, and cleans up by rolling back the volume on the guitar.

Like I said I am the King of the Cheap Guitar. I set out looking for an amp shell to turn into a cabinet, expecting to buy speakers and wound up with a working rig for $30, some spray on rubber and bits and pieces from the garage. I will likely replace the speakers at some point, when I get a really good deal, and then use these to build some smaller 1x12 speakers for other amps. 

Don't tell me wife, but I have about 9 amps in total. and they all are going to visit this speaker cab at some point.

BTW if you have a working amp that would fit this cab...

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Epilog Challenge V

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Epilog Challenge V

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1 Person Made This Project!


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5 Discussions


3 years ago

Just an update, I gave this cabinet to my son's roommate, he had bought his own '67 Bassman head, and being a college student had no money left. As far as I know 2 years later he is still using it.

So remember if you can help out another musician, do it!


3 years ago

So I get installing the 1/4 inch mono jack on the "new cab", but on the other end of things (the Epiphone Valve Jr.), do you use a "line out" jack? I have a Vox Da5 with a "line/phones" jack in the rear. Will this put all of the power of the Vox into the cabinet? Or do I need to modify the Vox or add some other kind of "output to cab"


Reply 3 years ago


Sorry for the slow response. What I was doing is building a cabinet to use with a separate head. A combo amp like yours is both the cabinet and the head in one. You would not be able to drive a speaker with the line out/phones jack, that has a very low output and would not give enough power for the speakers.

A small amp like that one often has a speaker that is designed to sound good with that particular amp, so you would not gain anything really. You might be able to use the line out to go to a mixing board, and then to a PA, but I doubt it would sound like what you want.

They no longer make the Valve Jr. but you can often find them online pretty cheap. They were a very basic tube (valve across the pond) amplifier, just one knob for gain/volume. It is a good first foray into the tube world because it will drive 4 ohm, 8 ohm and 16 ohm speaker cabinets. I have been interested in getting an Orange Micro terror or a Hotone purple wind to use with yet another cabinet made from a broken amp.

By the way, welcome to the guitarist world, soon you may acquire a lovely disorder called GAS (Gear Acquisition Syndrome). I started with one acoustic, one electric and a Peavey decade practice amp. Now over 40 years later, I have about a dozen guitars and basses, plus a mandolin and dulcimer. Then the amps, Including the ones out on permanent loan to my kids, 7 amps and at least 4 and maybe more speaker cabinets.

And I just got into Cigar Box guitars, and so I plan to build a Cigar Box Amp too.

Keep rocking!



6 years ago on Step 6

Very nice, FCD. I've looked at a few cooked amps that had the speakers still installed and thought the same. Seeing it actually done is inspiring!