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12 comments / Posted by Bruce Ohms

Introduction to Impedance

Impedance is something that can make or break your amp- literally! Even a general understanding of impedance can be a real lifesaver. This article will cover the basics of impedance and how it applies to your bass heads and speaker cabinets, specifically with matching them together.

Ohms and Impedance

The term impedance is used to describe a circuit’s resistance to electrical flow. An easy way to remember this is by thinking of the word impede. When the electricity from your amplifier flows to your cabinet, some of it is impeded. The amount of electricity that is impeded is the impedance. The impedance is measured in ohms, commonly represented with the Greek symbol Ω.

The higher the impedance is, the more resistance there is. This means that a cabinet with an impedance of 8 ohms will pull less power from your amplifier than a cabinet with an impedance of 4 ohms.

Oftentimes, you will hear musicians or engineers use the term load when discussing impedance. In this instance, this term simply refers to the bass cabinet or bass cabinets hooked up to the amplifier.

Impedance: Practical Application

If this all seems complicated, fret not! You don’t necessarily need to understand the technical ins and outs to save your amp from a fiery death. We will walk through a practical example below using a Carvin Audio B2000 bass amplifier and BRx10.4 cabinet.

This is the back panel of a Carvin Audio B2000. On the bottom right hand side, it lists the output power at each impedance. The B2000 puts out 2050W of power at 2 ohms, 1300W at 4 ohms, and 700W at 8 ohms. The amp has a 2 ohm minimum load, meaning that it will not be able to handle a load that is below 2 ohms.

Carvin Audio B2000 Bass Amp Back Panel 

B2000 Bass Amp Back Panel- Note Output Power Ratings On Lower Right


The Carvin Audio BRx10.4’s back panel shows that it has an impedance of 4 ohms. When paired with the B2000 head, this cabinet will receive 1300W of power from the head.

Carvin Audio BRx10.4 Back Panel

BRx10.4 Bass Cabinet Back Panel- Note Impedance Rating of 4 Ohms


If you decide to use an 8 ohm cabinet, the B2000 will put out 700W of power into that cabinet. To get the full 2050W of power from the head, you need to provide a 2 ohm load and will likely have to hook up multiple bass speaker cabinets (since 2 ohm cabinets are very uncommon). This is where we have to go back to math class for a little bit!

Combining Speakers

Let’s say you’re playing a big gig and want to bring along two Carvin Audio BRx10.4 bass speaker cabinets and wire them in parallel to the head- that is, hooking up each cabinet to the B2000 with its own speaker cable. To calculate the total impedance of this load, we will use a simple formula (assuming the impedance of each cab is the same):

Impedance of single cab / Total number of cabs = Total impedance

Plugging in the numbers from the BRx10.4 (just like in math class!) the formula looks like this:

4 ohms/ 2 cabinets total = Total impedance of 2 ohms.

So, using two BRx10.4 cabinets will give you an impedance of 2 ohms and pull 2050W of power from the B2000. You cannot hook up any more cabinets at this point, as you have already reached the specified minimum impedance of 2 ohms!

If you are using two 8 ohm cabinets, the total impedance for your load will be 8/2 = 4 ohms. If you want to use four 8 ohm cabinets, the total impedance will be 8/4 = 2 ohms.

Carvin Audio also offers an impedance calculator application that calculates the total impedance of all cabinets in your load. So if you want to double check your math or just don’t want to do math, this handy app is a lifesaver! 

Click Here to download it from the App Store.



  • Posted On July 02, 2016 by Ken Klosterhaus

    Back in the early ’70’s, my band wanted the clarity of Traynor Amp heads that we saw The Frost use, and the sheer awesomeness of Marshall stacks. We bought as such. My lead sounded like mud pies bubbling up in a lava pit when I leaned against it – but the sound man assured I was coming out loud and strong. I went to Ed Smith, who worked on major group’s equipment, and he told me the Traynor head did not match the impedance of the Marshall stack and would be very expensive to change. But, couldn’t I have added/subtracted more stacks, wired in parallel, to get the proper impedance? This always bugged me. Ed Smith is long gone and so are the Traynors and the Marsh cabs.

  • Posted On June 01, 2016 by bill Booker

    I Have a Carvin BX500 amp and a BRX 210 (4 Ohm cab). I also have a 10 Inch Eden 1 × 10″ Extension speaker. I have been hooking the Eden 1×10″ extension speaker to the extension speaker port on the back of the BRX210 cab and setting the BX500 to 2 ohms. Is this correct, or should I plug the Eden extension speaker to the back of the BRX500 amplifier and set it to 2 ohms?

  • Posted On June 01, 2016 by Boyd Garrett

    As a practical application of the example given above, if I plugged the second BRx10.4 into the “External System” on the back of the first BRx10.4, would that give me 2 ohms impedance? Or would they be effectively wired in series?

  • Posted On June 01, 2016 by Raymond Bennett

    to the man who blew his speakers, when you replaced you’re speakers you needed 4 ohm speakers, because what they do is run 2 4ohm into 8ohms, then the same with the other 2, then when wired properly the final load will be 4 ohms, I think you were running 2ohms and it couldn’t take it .

  • Posted On June 01, 2016 by Michael Sulkey

    “The Carvin Audio BRx10.4’s back panel shows that it has an impedance of 4 ohms. When paired with the B2000 head, this cabinet will receive 1300W of power from the head.”
    I was wondering, if the back of the BRx10.4 says “Maximum Power 1200 Watts”, and it’s receiving 1300 Watts, is that going to damage the speakers or electronics?

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