Finally i coated the aluminum plate with plexiglass (acrylic sheet colored dark gold) I ordered the output transformers in a local workshop, (Greece / Thessaloniki). All parts are mounted on the aluminum plate. The most convenient way to develop my idea was to use an already existing design.Ĭhassis are made of wood, and i build the whole construction in an aluminum plate (3mm thick). This simple and clever design was exactly what i had in mind. Once at a certain point, I came across the designs of the Decware SE EL84 Zen amp, which had quite good reviews among the tube amps DIY and Single Ended tube amp builders. Obviously such a construction requires the appropriate speakers, particularly horn type designs, so that the output of the amp can reach an efficiency satisfying level.
LM386 Power Amp A half watt power amp to use with headphones or small speaker.You don’t have to have anything but the poweramp to make a nice and simple practice amp. For more info check out the LM383 datasheet. Check out also Craig Anderton’s LM383-based practice amp. Kills batteries, but ok with wall wart supply. Drives nicely even a little bigger speaker. For a little bit higher power I’d go for National Semiconductor’s LM383 chip. ST Microelectronics’ TBA820 is also an interesting piece of silicon. You can use LM386 with headphones and a small speaker. National Semiconductor’s LM386 is a very simple chip that will give you ½ watt of power with battery operation. There are few IC’s that could be used with just a few external parts to do the trick. For headphones, I’d use this simple dual opamp design. There are several options for a practice man power amp. Remember that the bigger speakers you drive the shorter the battery life will be. If you want to play along with others, you might want to have a little speaker mounted in your amp. Battery life is long and the amplifier will be cheap and can be fitted into a small housing like a cigar box. If you want to practice without disturbing others, choosing headphone operation might be an ideal choice. Speaker or HeadphonesĪ practice amp can drive a pair of headphones or a few watt speaker. If you want a no-compromise EQ, use Len’s Three Band Active Baxendall EQ on his Practice Man. A Big Muff Tone Control will also make a nice and simple EQ. You can have a simple one band tone control circuit like explained in the Design Your Own Distortion-article. There are many different type tone controls. Adding a simple preamped mixer (like the one at AMZ) to the circuit after the preamp will do the trick. You might also want to add a walkman input for playing along to your favorite CD’s. It has a two channel preamp with a mixer control.
Or you could make a two channel opamp preamp so you could have a separate clean and distortion channels. Len Galasso has a nice design called PracticeMan. A simple preamp would just be your favorite distortion effect pcb mounted in the same housing with the amp. On the other hand, a simple preamp would make the amp much more versatile, but also it will increase cost and complexity a little bit. You don’t need to have a preamp in a practice amp. Well, build yourself a battery powered practice amp that you can take with you anywhere. Or maybe you want to warm your fingers backstage when your stack is already on stage. Or you left your Marshall Stack to your bassist’s garage, and wake up in the middle of the night with a great riff humming in your head. You can’t drag your 4×12 cabinets with you, and hate the feeling of playing unamplified. Well, what a great chance to practice your guitar playin’. Say you’re going to spend your two week vacation in a small cabin in middle of nowhere, where there’s nothing but time. Practice Amp Designs By Rikupetteri Salminen