This little guy is a cigar box turned amplifier for guitar practice or MP3 player. The idea behind this amp was to get a classic sound from a classic looking enclosure while re-using existing materials. This cigar box hails all the way from Nicaragua, and it’s wooden resonance gives it a beautiful, natural sound. The amplifier can be powered off a 9V battery or with a 9VDC power adapter. It has a volume knob and tone contour knob to set balance bass and mid tones. With a 1/4″ Switchcraft stereo input jack, an 1/8″ TRS adapter (not included) can give your MP3 player or phone the nostalgia of a 1960’s transistor radio. It’s a great looking addition to your shelves or coffee table while its portability lets you take it with you to the beach or picnic.
Here’s a demo of a previous build featuring Alex Wilson of Supersun. Results may vary.
Based on the Mitsumin Valvecaster circuit, this simple design is a 12AU7 preamp running on a mere 9V DC. I’ve found this thing to be useful for guitar, synth, and samplers giving a warm, lively edge to any small signal. It features Volume, Tone, and Gain controls. High gain results in a warm vacuum tube break-up while lower gain provide sonic color and texture.
Here are two audio samples of the triode. The first is made with two synthesizers (a Korg DW-6000 and a Novation Xiosynth) while the second is for guitar (a Johnson Telecopy). The first is recorded direct with no signal processing added except for a 6dB signal boost in the clean signal of the last set. The guitar samples were recorded on a Tascam DR-07 with a Bulgera 333 amp. Each section features a clean section followed by an effected section and so on. Each effected section adds more gain and volume each time through starting in the middle ranges and increasing to higher range. Maximum tone roll-off is demonstrated on the second variation of both demos.
This reverb stomp-box is based around the Belton Digilog reverb modules with a MOSFET driver circuit and JFET recovery. Separate Dry and Wet controls allow for a wide variety of saturation control. Toggle switch activates a pair of Germanium clipping diodes for a “dirty” reverb sound.