A homemade guitar amplifier is a cheap alternative to a store-bought amp. You can make your homemade amp to your own specifications, and because you put it together, you'll be able to carry out maintenance quickly and effectively. There are two main types of amplifier: tube and solid state. Tube amps use vacuum tube technology to amplify the sound, and solid state amps use transistor technology. Tube amps have less parts, so they're easier to assemble, but they require more maintenance than solid state amps.
Decide which type of amplifier you want to build. If you want a vintage sound, go for a tube amplifier. If you are more concerned about reliability and do not wish to carry out much maintenance, choose a solid state amplifier.
Source the parts. There are three main components in any type of amp: the preamp, power amp and speaker. The number of cathodes and resistors and type of turret board will depend on which type of amp you're building. The easiest way to get all of the parts is to purchase a homemade guitar amplifier kit. The amp kit will come with a schematic, which is an essential guide for building the interior circuit. Only the most experienced professionals should attempt to assemble a homemade guitar amp without referring to the schematic. Most amp kits come with a cabinet, but you can purchase cabinets separately as well. (Kit makers will often sell cabinets and other parts individually.)
Set up a suitable workspace. You'll need enough space to lay out all of the homemade guitar amp components.
Check the parts for damage. Any metal part that has rust should be discarded and replaced.
Prepare the cabinet. Ideally, your cabinet should be oversized in relation to your components. Aim for a cabinet that is at least four inches larger than the diameter of the speaker. This will give you plenty of room to work. There should be a shelf for the preamp and a separate compartment for the power amp. The speaker will be screwed in to the interior of the cabinet.
Insert the preamp. The preamp has all of the dials and input jacks. It should sit snugly in its compartment with the front panel exposed.
Fit the power amp. Position this close to the preamp for easy wiring.
Load the speaker into the cabinet. There will be a series of holes running around the edge of the speaker cone for you to screw the speaker into the amplifier cabinet.
Complete the circuit. Consult the schematic and insert the relevant cathodes, resistors and capacitors in the correct position. Then solder all the parts together using a soldering iron.
Test the amp. Plug in to the amp to make sure it is fully working, then, if you chose, you can enclose the back of the amp.
Screw the speaker in tight enough that it doesn't rattle, but not so tight that you can't remove it in the future.
Make sure that your work area is well ventilated.