Introduction: DIY Cheap Solid-state Amplifier (from Salvaged Parts)

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About: i love building and recycling things, since i was young, music/gaming/BMX

Living in a third-world country, amplifiers like marshall, fender, line6, peavey and others are just too expensive for poor guitar players like me, since most amps are toys for the rich boys. So with a mix of inspiration and imagination I came up with this design and idea. I always wanted to have an Amp head since they look way cooler than combo amps, so this gave me an inspiration for my new build an amp head, (this instructable can also be used for making a combo amp).

If you have any practice amps that you have not used or somehow not working anymore, then it is the best time to give it a make-over, I'll give you an inspiration on how to give your amp a new breathe of life.

In this instrcutable I will build an amplifier out of salvaged parts from existing guitar amp that I have and add other circuits to give new sound to the amp. One good thing about this is that it is cheap.

I salvaged a damaged 10watt practice amp and a 150watt PA amp that I have a long time ago, I made other circuits to give the old amp a new sound.

You have the option to build it in a combo type manner or a cool looking amp head.

Step 1: Gather the Parts

Before I made my amp I had to search and build other circuits to give it a new sound.

Materials:
Any salvageable amplifier,
soldering Iron and lead
cutting tools(wire cutter, strippers and the likes)
wires
tester
drill
breadboard(fro prototyping and testing circuits before soldering it)
PCB, Ferric acid(if you like to etch)
universal PCB(if you hate to etch)
components(resistor, opamp, transistors, diodes, capacitors etc.)
9-12volt power supply(use to test your circuit) or a 9v battery

--------additional circuits---------
I decided to build the simplest circuits (since I it is difficult to find most of the parts needed for complex circuits especially in the country where I am from). any circuit you can think of can be used whether it is a transistor, op amp or valves(but I would discourage you with using valve pre amp since it would just kill the beauty of the valve sound if you pair it with a 10 watt practice amp it is not worth it).
-->Tonemender from runoffgroove
-->Trotsky overdrive from beavis audio
-->LM386 design
-->ua741 design
-->some tone stack designs.

Materials(Casing)
This may vary as to what is available that you have right now.
but for my design I used
-3/4" plywood

Step 2: Testing

Before we could mash up every circuit we have and built to one useful unit you need to test them first.
First test the amp itself. The 10watt amp that I had, was a pain in the ass to fix, since it didn't have any schematics I had to pay close attention as to what part need replacements. 

If you are using a 10watt amp same as me, chances are the power amp section has the TDA2030 IC, perhaps the pre-amp section would be anywhere from a 4558 or a TL072. I will talk about how I resurrected the amp. First the problem with it is that the TDA2030 it was busted since it was originally fitted with a very small heatsink, I took it out since I do not need it. There was bad oscillation  when the amp is cranked up, since TL072's from my experience would oscillate or hum due to the wear on it over time or it experienced some bad case of malfunction, since the original board had the 072 mounted directly with no IC holder, I took it out and placed holders and placed new 072's. after that the amp sounded well even if I cranked it to 10.

The circuits that I have build were also tested to ensure that everything would sound good. I had to build a separate power supply for my additional circuits since the power supply section of the 10watt amp does not have a regulator.

Step 3: Putting Them Altogether

Depending on what kind of guitar amp you salvaged or recycled most amp would follow this design [preamp-->poweramp-->speaker], the key to making this ible successful is knowing where to alter the existing board to make it useful. Knowing where the power amp section input and the output of the pre amp section is very important since this is the junction where the major alterations would be done.

If the amp you are using is equipped with IC's better check what IC is it, and look for the data sheet. The data sheet will give you an overview of anything you need to know about the chip especially the pin configuration.

Step 4: Solder and Wire Them Together

Now that the amp is almost finish all you need is to connect the dots and finish everything.

Step 5: Power Amp Section

I had a 150watt PA amp that I dissected. Since most PA amps have Microphone inputs and sometimes they lack tone controls. I traced the circuit where the Power amp section and pre-amp section meets and cut them out. Now I can attach an input jack directly to the PowerAmp section. Re-cased the entire thing since I gutted out some unwanted circuits.

Step 6: CIRCUIT PROTECTION

THIS IS THE MOST IMPORTANT PART OF BUILDING ANYTHING THAT INVOLVES ELECTRICITY.

-->always put a fuse on the power section,
-->avoid exposing bare wires, my work may look like a mess but every bare wire are wrapped in electrical tape.
-->use heatsinks, most of the IC's used in the power amp section should be paired with a heatsink to prevent heat from destroying it, if you are a paranoid parrot like me, you could add CPU fans to ventilate everything.
-->DOUBLE CHECK or even triple check your circuits from short and other hazards that can destroy your circuit or cause electrocution on you.
-->Your tester is your best friend, learn how to use it wisely
-->if unsure you can ask guys here in instructables for help or sign up on electronic forums to help you out.

Step 7: Casing

Casing is all up to you, my amp has a wooden frame, the front panel is hard type of plastic which I do not know what material it is made from.

Step 8: Other Things

Since the circuit has some components that heat up, heatsinks should be placed on it. I also decided to put CPU fans to ventilate everything inside since I made a very small amp head, it also adds a "cool" factor to me. I added some LED lights inside just to make it look more cooler. You could add footswitches if you like (I will still be building mine). Effects send and return is also a good addition to the circuit.

Step 9: Test Driving the Amp