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just got my new rig!! some questions!?

Discussion in 'Amps and Cabs [BG]' started by BLonge, Feb 2, 2005.


  1. BLonge

    BLonge

    Jan 8, 2005
    Massachusetts
    aight i have a new peavey firebass 700 head (700@2 475@4 275@8) and a used peavey tvx 4x12. things loud as hell and i love it so far. this is my first rig,a big step up from my combo, so i have some questions:

    the cab is rated for 4 ohms..is there a way to ensure that my cab is getting the correct amount of wattage so it doesnt get damaged or anything? and how do i know that my amp is operating at 4 ohms?

    also, my amp has DDT speaker protection. is anyone familiar with it and how it works? should i be concerned if the red light is coming on? i guess when the red light comes on it is compressing the signal..but when should i be concerned that its working too hard or something?
     
  2. Brendan

    Brendan

    Jun 18, 2000
    Austin, TX
    Unless it has seperate inputs for 2, 4, and 8 ohm operation, your cab is getting however much power the resistance of the cab alows.

    For instance, if the input says "2 ohm minumum" it means when you plug your 4 ohm cab in, the head sees it as a 4 ohm load, and puts out the rated power. Same with an 8 ohm or 2 ohm load. Just don't got lower than 2 ohms (two 4 ohm cabinets)

    You're fine, in other words. It'll handle the power the head is giving it, and the head is only capable of putting out so much power at 4 ohms, so you're not going to wreck the cab just plugging it in.
     
  3. Congratulations. Now go buy some earplugs or you will regret it 20 years from now.

    There might be a rating sticker on the back of the cab that says something like "4 ohms 300 watts". If the amp is capable of 475 watts output into a 4 ohm load you want a cab that can handle the power. A 100 watt cab played at high volume might be in trouble, but if the cab is rated over 250 watts or so you should be OK. If you hear a lot of distortion from the cab you know you are pushing it too hard.

    A solid state power amp will typically drive anything from 2 ohms and upward. The output of the amp varies with the reactive load of the speaker cab, and the impedance of the cab varies as it is driven. In short, don't worry about it, the amp is delivering the right amount of power.

    I'm not overly familiar with DDT, but I believe it is an automatic compression circuit. It is designed to protect the power amp from exceeding its limits and distorting. If the light flickers sometimes that's OK, but if it is on all the time you are probably boosting the low frequency EQ too much. Boosting the lows a lot demands a lot of the power supply.

    Rick B.
     
  4. BLonge

    BLonge

    Jan 8, 2005
    Massachusetts
    yeah the cabinet can handle 450
     
  5. Brendan

    Brendan

    Jun 18, 2000
    Austin, TX
    You're fine, power wise. You can generally put anywhere from 2-3 times the amount of power and be fine (you just don't need to turn it up to 10. More like, 4). I regularly put 700 watts into a cab rated for 300, and there's never been a problem. It's almost impossible to "overpower" a cab as long as you keept the volume reasonable. Cranking a 1000 watt poweramp into a 1x10 will do damage, but if you're merely using it at an appreciable volume, you're fine.

    Obviously, you shouldn't try to use 2000 watts to make a 200 watt cab compete with two half stacks, but you're just as likely to damage a cab if you're trying to make a 100 watt amp compete with the same. But then that'd be underpowering a cab, and driving the amp into clipping.