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
Any salvageable amplifier,
soldering Iron and lead
cutting tools(wire cutter, strippers and the likes)
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
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
-->some tone stack designs.
This may vary as to what is available that you have right now.
but for my design I used
Step 2: Testing
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
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
Step 5: Power Amp Section
Step 6: CIRCUIT PROTECTION
-->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.