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Amp basics

Discussion in 'Amps and Cabs [BG]' started by StingrayKid21, Feb 10, 2002.


  1. StingrayKid21

    StingrayKid21 Holding down the low-end since 1996.

    Oct 7, 2001
    Portland, OR
    Hey everyone,

    I have a confession to make... I am extremely confused about how the whole amp deal works with seperate components, i.e. amp heads, power amps, cabinets. I am thinking about upgrading to a new amp setup but I don't want to buy another combo amp. I look at all the different amps and cabs available but its a little intimidating. For instance, the cabs have ratings for RMS wattage and Program wattage... what does that mean? I don't want to buy a great cab and a lousy amp or vise-versa and I definately don't want to destroy a cab by running too much wattage through it. If anyone knows of a website or anything that explains how all of this stuff works then I would really appreciate it!

    Thanks!!
     
  2. lo-end

    lo-end

    Jun 15, 2001
    PA
    Ok well I can go over some of the basics with you. To start off, most beginner amps are "combo amps," or amps that have a preamp, poweramp, and cabinet all in one. The preamp is the part of the amp with the little knobs that modifies your sound. The poweramp amplifies your sound to make it loud. The speaker cabinet is the actual speaker that everything goes through.

    When you buy a preamp, all you get is the sound-shaping device.

    When you buy a poweramp, all it does is clean amplification. Or, it just amplifies but doesnt shape your sound at all.

    A speaker cabinet is just an enclosure with one or more drivers in it to make you hear everything.

    A head is a preamp and poweramp in one that you can hook up to a cabinet.

    I will explain RMS and program later.
     
  3. Ty McNeely

    Ty McNeely

    Mar 27, 2000
    TX
    RMS is the limit of steady power that can go into your amp at one time. Program (or peak) is the most that you can have going through it at one time.
     
  4. StingrayKid21

    StingrayKid21 Holding down the low-end since 1996.

    Oct 7, 2001
    Portland, OR
    Hey,

    Thanks for the info lo-end. Just knowing the difference between a power and pre-amp is very helpful. I noticed on your profile that you have an SVT-4 Pro... that is an amp head that has both a power and a preamp, right? That is what I am hoping to buy eventually, but right now I'm working on buying my second Stingray. Would an SVT-4 Pro work well through a 4x10 cab or would it be too powerful? And if you have time to explain the whole RMS program thing sometime then that would be awsome!

    Thanks!
     
  5. lo-end

    lo-end

    Jun 15, 2001
    PA
    Yes, an SVT-4 has a preamp and poweramp in it. All proper bass heads have both of these in them. (By the way, the SVT-4PRO also has a built in compressor, crossover, and 9 band graphic EQ :cool: )

    And no, it would not be too powerful for a 4x10. I use a Mesa/Boogie 4x10 with mine and it is perfectly safe. When you bridge the SVT-4PRO's dual channel poweramp, it puts out 900 watts RMS into my cab's 8 ohms. My cab handles 600 watts. You might think this is unsafe because my SVT-4 can put out more power than the cab can handle, but this is not necessarily true. This is what is called having "headroom," and is a good thing. The extra power can only hurt your cabinet if you have the thing really crank up; luckily my Mesa can get REALLY loud, so I never have problems with overpowering it.

    Here's a thread I started back in October about the definition of headroom. There are some good explinations in here:

    http://talkbass.com/forum/showthread.php?threadid=28783
     
  6. lo-end

    lo-end

    Jun 15, 2001
    PA
    Heres another newbie mistake: When some people buy their first real bass rig (head and cab configuration) they think that its ok to hook it up with instrument cable. This is WRONG! There is no immediate danger in doing this, but your instrument cable will get HOT and you will lose a lot of volume. Trust me, my little brother made this mistake when he got a Marshall 2x12 extension cabinet for his Fender Frontman 15G guitar amp.

    The proper thing to use is SPEAKER cable. There are many different kinds of speaker cables, some are terminated with 1/4" plugs, speakons, bananna plugs, or just wire screwed into binding posts. The cable itself can vary as well--you can use the side by side "lamp cord" configuration, or the twisted pair kind with a PVC jacket that is commercially made by companies like ProCo and Monster Cable. Whatever you use, try not to go thinner than 16AWG. 18 is kinda pushing it, especially if you like longer speaker cables.

    The reasons why you need speaker cable and not instrument cable are very simple. Instrument cable has a coaxal configuration and is shielded. It is also a much higher gauge (it's thinner) than regular speaker cable.

    Here are pictures of each to show the differences in cable construction:

    [​IMG]
    Instrument Cable

    [​IMG]
    Speaker Cable