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I need help with amp terms...

Discussion in 'Amps and Cabs [BG]' started by BassGuitarNerd, Apr 2, 2005.


  1. I am still a little new to the whole amp scene. I have had my bass guitar for about 2 years now and I still only have my little 15 watt amp that came with it. I am going to buy a new one but i am a little confused by the terms they use. Can someone describe to me what the differences are between the following. This will help not only me, but anyone else who is confused. Thank you! :)

    Preamp

    Power amp

    Head

    Cabinet

    Stack

    This might seem like a really stupid post but it would really help me out. If there is any additional info i might need please post it. The only thing i know about are combo amps, but when I need something a little better I will need to learn what all those terms mean. Thanks again! :)
     
  2. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    1st off the faq sticky at the top of the forum has tons of info, so does the search function

    Preamp - a device for amplifying the low level signal of your pickups to a line level suitable for inputing into a poweramp. also usually contains eq

    Power amp - takes the line level from a preamp and amplifies it to a speaker level signal capable of driving speaker cabinets

    Head - contains a preamp and poweramp

    Cabinet - this is a box with one or more speakers

    Stack - generally refers to a head on top of one or more cabinets
     
  3. Mcrelly

    Mcrelly

    Jun 16, 2003
    Minnesota, USA
    your "amp" is probably what is refered to as a "combo" or "combo amp" it has a 'preamp','amp' and 'cab' all in one box.

    Preamp: is an electronic circuit that take your very low voltage guitar signal and makes it bigger, plus it usually consists of tone controls like bass, mid, treble etc... when this is in a separate box from the amp or cab it is called a preamp. this voltage level is usually sent to a power amp or a mixer.

    AMP: or power amp takes the preamp signal and makes the voltage even louder to be sent to a loudspeaker or cab. the signal out of a power amp should ONLY go to a speaker cabinet designed to handle these voltages.

    Head: is a combination of a preamp and power amp in one package.

    Cabinet: is a box with loudspeakers in it. make sure the wattage rating of the cabinet is about same or more than the 'amp' or 'head' can put out at maximum average level.

    Stack: is the pile of equipment sitting on the stage like: cabs poweramp and preamp.

    Rack: usually if you move your equipment around to different performances or 'gigs' you will put you preamp and poweramp and other devices in a 'rack' or special case where you can mount these devices so that there are protected from damage of move from home to car to gig etc....

    there are many things to consider before moving up, but that depends on how much money you have to spend, how loud you need to play, whether you bass speakers are just for you to hear yourself or for the whole room to hear you, how much you like to carry in one trip, sound quality or your tastes.

    I've been playing for six years and play mostly at a kids church service, loud, but not bar loud, but I currently would not be very happy without the system listed in my signature, which cost me about $2,000 USD not including my $600 ric. but just to move up a bit from what you got and get some thing louder and maybe good enough for a basement jam. if you got a 100-200w combo with 2 10" speakers or a 12" or a 15" you can expect to spend at least $400 USD new In my opinion. check out yourkville, SWR, ampeg combos
     
  4. Thanks for the help!
     
  5. Joe Beets

    Joe Beets Guest

    Nov 21, 2004
    You can use your little 15 watt practice amp to demonstrate the principle of T.O.F. You will need to know this when you go out to buy new gear and when you start playing in a louder setting, like when your guitar player gets a new Rogue 100 watt stack. Turn the volume on your amp up slowly as you thump away on the "E" string with your other hand. At some point, probably sooner than you'd like, the tone will break up and each note will sound like a series of short farts. This is called T.O.F., or the "Threshold of Farting". When purchasing new gear, especially combo amps, avoid gear that makes this sound. Unless,of course, T.O.F. is the sound you're after.
     
  6. BassIan

    BassIan Supporting Member

    Apr 27, 2003
    Cupertino, California
    This has been covered before, but I beg to disagree. Many people on this site prefer to power their cabinets with amplifiers that sometimes double the cabinet's rated power. This is because given the dynamic signal of a bass, the amplifier will rarely be applying its full voltage to the speaker cabinet. There are two camps here, but the one thing that is agreed on is that clipping the amp (driving it too hard into power amp distortion) is BAD (unless you are using a full tube power amp, then it's SWEET). Regardless of setup, always keep an eye on this.

    Just wanted to make sure this was clear.
     
  7. Magic Smoke:
    All amps have magic smoke in them, it's what makes them work. Abusing your amp often lets the magic smoke out. You don't want to do this! If you see the magic smoke escaping from your amp it means that catastrophic failure is eminent. Sometimes magic smoke can escape without your seeing it (it is magic after all) and the amp will stop working or start behaving oddly. If this happens, take your amp to a reputable repair guy and ask him to refill it with magic smoke. He'll be happy to do so, albeit at a price.
     
  8. Heh, Thanks everyone! :smug:
     
  9. Mcrelly

    Mcrelly

    Jun 16, 2003
    Minnesota, USA
    what I meant to say was "at least the same wattage as your cabs" I agree that more power to cab rating is preferred for best sound, but I was thinking in terms of moving UP to another cab, say he buys a 300w cab it would be great to have 300w (into number of ohms of cab) rather than say 100w. 300w amp might be cheaper than a newbie trying to afford a 600 or larger amp.

    for a couple of years I ran 350w (4ohm) into two 250w (8ohm ea.) cabs. sounded loud, but not extremely dynamic. now I run 1200 (4ohm) into two 300w (8ohm ea.) cabs. sounds great