AMPs -> Heads? Cabinets? Huh?


New member
I've always been wondering. About stack amps, they consist of a head and a cabinet right? Whats the difference between the two amps? Why does it always come in the form of head + cabinet. Also, some live bands have cabinets without heads. Either way, I'm confused. Anyone care to explain?
By Head+Cabinet, you mean combo right? So are you asking he diffence between stack amps and combo amps?
Amplifier heads are units where the preamp and poweramp stages resides. Usually amp heads have tubes for tube amps but there are solid state amp heads as well.
Cabinets are meant to house speakers that receive signals from the preamp and poweramp.

Combos are called combos because the speakers and the preamp/poweramp...come in 1 piece.

Hope that kinda sums it up.
??? 8O

OK I will start from the beginning.

Stack amps: the stuff you see at rock concerts. Small rectangular power unit on top of a square speaker cabinet. Able to Like up to 8 speakers(2 4X4 cabs). Flexibilty lies in that the two units are modular. Mix and mach possible. Think of the huge marshalls in Davis.

Combo Amps: the whole amp is one single unit and cannot be seperated. Think fender. Flexibilty lies in fact that here is less hassle when moving gear about.
BlackMoo said:
Is there a diff in sound freq. or tone between the 2?

There are differences once you have the flexibility to modify the build and dimensions of the cab as well as the speakers it is equipped with.

Are these factors audible? Yes, very audible.

As a rule of thumb, having a head rather than a combo allows you to swap between different cabs (each with different specs), rather than being restricted to just one.

Portability is hard to gauge. A head is easier to carry (my Univalve for example can be ported around in a small equipment bag) but is dependent on whether the final play area is equipped with a cab.

The combo is heavier amd bulkier but facilitates immediate plug-and-play.
I think what you saw as "cabinet without head", is actually performers using rack mount pre-amp, effects & amp module. Very much like pro-audio stuffs normally packaged into 19" flight case for convenience.

Major brands (marshall, mesa, SWR....) do produce 'high end' rack mount equipments. These are normally placed way behind or the side of stage.

Bass performer more often uses such config than guitarist, as their amps are very heavey and powerful.

Combos are more often used by guitarist as their amps are normally not that high power, as combos are more affected by rattle problem caused by heavy bass sound. The guitar voice is more mid range, less rattle, so this problem is not common. A combo is much more convenient and light than rack equipments.
BlackMoo said:
Looks like I've got alot to learn about amplification...

heh. me too.

i notice most gigs don't have speakers; they just provide the combo amps for you. So sometimes you just can't use the head you bring? (assuming there's no power amp in.)