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Help a newbie with some amp ?'s

Discussion in 'Amps and Cabs [BG]' started by bassplayerjojo, Feb 22, 2002.


  1. I have recently decided to upgrade my amp system, I am currently running through a 150w combo amp. I have my eye on the Gallien Krueger 1001RB Head:

    (Low-540W@4ohm, 340W@8ohm, 1kHz.
    High-50W@8ohm, 5kHz.
    Continuously Variable Speed Fan.
    Ultra low noise S/N>90dB, Clip LED and
    10dB Pad, Volume, Mute Switch and Mute LED.
    5/4 String Bass, Adjustable Contour and Presence.
    Bass Specific Series Four Band Active.
    Boost, Tweeter Level with Hi-Cut Switch
    and Woofer Level with Crossover Switch.
    XLR, Level Control, Ground Lift and Pre/Post Switches.
    Send, Return and Tuner Out.
    Two 1/4" and Two Bi-Amp Connectors.
    18 lbs.)

    and a 410RBH to go with it.

    (8 ohms or 4 ohms.
    800 Watts.
    4xGK-Paragon 10B200-32
    Cast Frame, 10", 200W,
    32 or 16 ohms High Presence Voice Coil.
    GK-Paragon 5H50-8.
    50Hz to 19kHz + 5dB.
    103dB.
    Switchable Bi-Amp/Full Range, Horn Power Limiter,
    L-Pad High Frequency Attenuator,
    Switch (Bi-Amp/Full Range).
    1xBi-Amp Connector.
    1x1/4" Full Range Only.
    All Birch Cabinet, Black Carpet,
    16 Gauge Steel Grill,
    Nickel Plated Castors,
    Custom Tooled Interlocking Corner System
    and Dual Front Loaded Ports
    92 lbs.)

    My first question is about the ohms. Not sure how that all works. If 4 ohms gives me 540w, wouldn't I always want to run at 4 ohms? What is the benifit of running at different ohms? Which brings me to the next question...on the rear panel of the cab it says 400w 8ohms, its just lettering there, its not a switch. Now if I wanted to change that and run at 4 ohms, how would I go about doing that?

    Now I'm already paying $750 for the head, and $900 for the cab. Another question I have is, what exactly does a preamp do, and should I get one? I'm not really all that concerned with money.

    And my last question I promise..Eventually I'm going to be expanding my rig. Can I buy another cab (say a 115 or a 210) and run it along with my 410 throught the same head, and what effect will this have on my wattage and ohms?

    Thanks in advance for all the help =)
     
  2. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    Solid state amps can operate into loads down to a minimum impedance (2 or 4 ohms for most amps). The higher the impedance, the less power delivered.

    The cabinet you are looking at is 8 ohms impedance, period. Depending on the drivers inside you might be able to rewire it to 16 ohms or 2 ohms, but definitely not 4 ohms.

    The benefit of running at different impedances is when you add another cabinet, if it is also 8 ohms the total impedance now becomes 4 ohms and the amp can still drive this OK.

    A lot of people feel as if they are being robbed if they don't get full power out of their amp at all times, but it's a tradeoff so you can add extra cabinets later. Many combo amps deliver full rated power to their speaker(s) but then you can't add extensions.

    So how much do you lose having only 340 watts instead of 540 watts? 2 dB in maximum volume is all, this is noticeable but not a large amount. To sound "twice as loud" to your ears an amp has to be 10 dB louder, which is ten times the wattage!!