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Can someone break these down into layman terms

Discussion in 'Amps and Cabs [BG]' started by Soapbox Prophet, Aug 21, 2001.


  1. okay, im relatively new to playing bass, its been a year or so, and I still don't know what all the terms used mean when a company is laying down specs for an amp.....like here, are the the specs for an ampeg extreme series cab....now what do each of these mean? and how do they matter?

    Component 1: Magnet Weight : 109oz
    Component 1: Size : 1x15' Cast
    Component 1: Voice Coil : 4'
    Component 2: Magnet Weight : 30Hz
    Component 2: Size : 2x8'
    Component 2: Voice Coil : 2'
    Component 3: Magnet Weight : 14oz
    Component 3: Size : Bullet Horn
    Component 3: Voice Coil : 1.25'
    Crossover Frequency : 200Hz / 4KHz
    Frequency Response (-3 dB) : 40-18KHz
    Maximum SPL : 122dB
    Nominal Impedance : 4 or 2x4 ohms
    Program Handling : 600 Watts
    RMS Handling : 300 Watts
    Sensitivity : 98dB
    Usable Low Frequency (-10dB) : 33Hz

    alright, any help is good help. thanks!
    christopher
     
  2. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    Ok, my try:

    You can pretty much forget about magnet specs and construction data.

    Now the crossover frequency:
    It tells you that the lowest speaker
    (15') gets the signal up to 200Hz, the two 8s get 200Hz-4kHz and the tweeter anything above that.

    Frequency response: the frequency area that can be delivered by the cabinet with a volume deviation of up to 3dB (since it's a logarithmical value, 3dB means half as loud, +3 dB is twice as loud.

    Maximum SPL: SPL - sound pressure level
    122dB is the maximum volume that the cab can deliver without excessive distortion.

    Impedance: same as resistance, but in an AC circuit.
    Only important with regard to your amp. When amp can only handle loads down to 4 ohm, you can only use one cab with it. If it can handle 2 ohm, you can use two in parallel.

    Program and RMS: Two different methods of measuring the power a cab can handle, with different signals.
    RMS is more preactical as it shows the power that the cab can handle over a longer amount of time.
    Porgram, music or peak power shows the power peaks that can be handled.

    Sensitivity:
    A signal with the power of 1W is fed into the cab and the volume is measure 1 m away from the box.
    The higher the dB rating, the more volume you can get from your amp.

    ULF tells you the lowest frequency that is not quieter than 10dB compared to the rest of the signal.
     
  3. MikeyD

    MikeyD

    Sep 9, 2000
    Pretty good post, JMX. It should be pointed out that +3 dB reflects a doubling of power, not loudness. To our ears, it takes about a 10 dB difference to seem twice as loud. Of course, that means ten times the power.
    It reflects the volume at 1 meter that the cabinet would produce at its maximum rated power (300 watts RMS in this case). Whether or not this corresponds to excessive distortion is another issue. The power rating (and hence the derived volume figure) usually deals with the ability of the drivers to dissipate heat. Excessive distortion could occur if the cabinet is driven to higher wattage levels (if briefly) - or at even lower power levels if at extremely low frequencies. For example, it probably doesn't take that much power to make coils bottom when feeding an 8 Hz. signal into the cabinet.

    - Mike
     
  4. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    Thanks for the corrections. :)
     
  5. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    Well I would say - just listen to it and if it sounds good buy it - don't worry about the specs!

    That's a "layman's view"!! ;)
     
  6. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    Well, I think you should at least know about power handling and max.SPL/SPL 1W/1m.
    It sucks when it sounds great in the shop (it almost always does) and you get buried live or at rehearsal.

    Knowledge is power. And will save you money in this case.