The four types of amplifiers are solid-state or analog, tube, modeling or digital, and hybrids.
Solid-state amplifiers are called thus because they have transistors for the preamp and power systems and not tubes. These amps are very durable and rarely, if ever, need repairs or replacement. Normally, they have a clean tone, however some have been known to have several distortion channels as well.
Tube amplifiers are favored among artists for their warm, fat tone and organic distortion. With the same wattage, these amps will be louder than solid-state. Most amps of this type can change between separate channels quickly and easily. The tubes that give these amps their name will require replacing over time as they tend to fall apart.
Modeling or digital amplifiers use digital processors to imitate the sound of the tube technology. With the imitation software, these amps can make many different sounds. They have programmable effects that will change the sound as the artist desires. Some are designed to go directly into the recording device.
Hybrid amplifiers put the best parts of the other amps into one package. These hybrid amps use tubes as well as the solid state power of analog amps. Valvestate amps have tubes in the preamp section to create the tube sound and the solid state in the power section. This way power tubes do not need to be used in order to create the same sound as the tube amplifiers.
Beyond the different type of amplifiers, amps come in different configurations. Combos, short for combinations put together amplifiers and speaker into one unit. You can buy amps separate and speaker units. This allows you to customize amp and speaker combinations at your will. This also makes the entire thing easier to carry as the parts are separate. This combination is normally called a stack.
The way the amplifier is constructed makes a difference. For one the width of the wood used can determine the quality of the sound. If the wood is too thin, then the vibrations might shake the paneling loose. The wood should be at least a half an inch thick in order to maintain structural integrity and give out a good quality sound. Some amps have open backs and others are completely closed off. Those with a closed back will have a better bass sound.
The Size and Power of Speakers vary greatly and are reflected in the price and intended application of the speakers. Amps designed for practice are normally solid state or a combo of solid state and modeling with low power ratings of roughly thirty watts or lower. They are typically small, eight or ten inches as most. There are few tube amps that can be found. Speakers deigned for rehearsals or playing for a small crowd tube or modeling amps twelve inches in size with at least fifty watts are ideal. When performing loudly or for a large audience the power rating should be upwards of a hundred watts. Twins or combo amps with two twelve inch speakers can be used for this as well. This is where a stack would come in handy.
Most amplifiers have built in effects that can distort the sound of the guitar player. When buying an amp, the effects that are built into it should be considered. If one does not have the effects you want, then consider a different amplifier.
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