Here the guitar power amplifier circuit which will deliver about 100W audio output. This is transistored amplifier, heatsink is a must.
The speaker and line out connections allow up to two 8 Ohm speaker cabinets (giving 4 Ohms), and a line level output for connection to a direct injection (DI) box. The level is about 1.3V (or +5dBm) at full undistorted output - change the 560 Ohm resistor to modify the level if desired.
The two 1 Ohm resistors must be rated at 10 Watts (they will still get quite hot, so mount them well away from other components). These can be mounted to the heatsink with small brackets if you want to keep them a bit cooler - remember to ensure that the heatsink can handle the extra heat input, as these two will add about 10 Watts of additional heat energy. The four 0.1 Ohm resistors should be 5W types. The amp is otherwise quite conventional. Use the parallel arrangement as shown, anything less will cause the transistors to be operated outside their safe operating area, which will result in the eventual failure of the output stage.
Make sure that the two bias diodes are mounted well clear of anything that gets hot - including the heatsink. These diodes are the two in series. All diodes should be 1N4001 (or 1N400? - anything in the 1N400x range is fine). A heatsink is not needed for any of the driver transistors.
The life of a guitar amplifier is a hard one, and I suggest that you use the largest heatsink you can afford, since it is very common to have elevated temperatures on stage (mainly due to all the lighting), and this reduces the safety margin that normally applies for domestic equipment. The heatsink should be rated at 0.5 degree C/Watt to allow for worst case long term operation at up to 40 degrees C (this is not uncommon on stage).
Make sure that the speaker connectors are isolated from the chassis, to keep the integrity of the earth isolation components in the power supply.
The speaker and line out connections allow up to two 8 Ohm speaker cabinets (giving 4 Ohms), and a line level output for connection to a direct injection (DI) box. The level is about 1.3V (or +5dBm) at full undistorted output - change the 560 Ohm resistor to modify the level if desired.
The two 1 Ohm resistors must be rated at 10 Watts (they will still get quite hot, so mount them well away from other components). These can be mounted to the heatsink with small brackets if you want to keep them a bit cooler - remember to ensure that the heatsink can handle the extra heat input, as these two will add about 10 Watts of additional heat energy. The four 0.1 Ohm resistors should be 5W types. The amp is otherwise quite conventional. Use the parallel arrangement as shown, anything less will cause the transistors to be operated outside their safe operating area, which will result in the eventual failure of the output stage.
Make sure that the two bias diodes are mounted well clear of anything that gets hot - including the heatsink. These diodes are the two in series. All diodes should be 1N4001 (or 1N400? - anything in the 1N400x range is fine). A heatsink is not needed for any of the driver transistors.
The life of a guitar amplifier is a hard one, and I suggest that you use the largest heatsink you can afford, since it is very common to have elevated temperatures on stage (mainly due to all the lighting), and this reduces the safety margin that normally applies for domestic equipment. The heatsink should be rated at 0.5 degree C/Watt to allow for worst case long term operation at up to 40 degrees C (this is not uncommon on stage).
Make sure that the speaker connectors are isolated from the chassis, to keep the integrity of the earth isolation components in the power supply.
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