Find out the minimum load your amp can handle.
Every bass amplifier has a specific minimum load that it can handle. Usually, 4 or 2 ohms. An amp that handles 2 ohms minimum can drive any speaker or speaker combination that creates a 2 ohms total load or higher. The minimum load of your amp is usually specified at the speaker output on the back, and also in the manual.
Make sure the speaker, or combination of speakers, does not produce a total load below your amps minimum load.
Every speaker cabinet produces a specific load. Most cabinets for bass produce either 4- or 8-ohms load, in rare cases 2-ohms. This value is known as the speakers’ impedance.
If using two cabinets together the total load (aka impedance) will not be the sum of the two cabinets’ load together, but a division based on a specific calculation.
If all speaker cabinets have the same impedance, then the calculation is easy. Simply divide the impedance by the number of speaker cabinets you intend to connect to the amp.
Example 1: 2x 4 ohms speaker cabinets: 4 divided by 2 = 2 ohms.
Example 2: 2x 8 ohms speaker cabinets: 8 divided by 2 = 4 ohms.
Example 3: 3x 8 ohms speaker cabinets: 8 divided by 3 = 2.67 ohms.
If using two speaker cabinets with different impedance together, the total load will not end in an even number. For example, one 4-ohm speaker paired with an 8-ohm speaker will produce a total load at 2.67 ohms.
We recommend using cabinets together that has the same impedance, but if you insist, here’s the formula to calculate the total load when using two cabinets of different impedance:
(impedance of cab 1 X impedance of cab 2) / (impedance of cab 1 + impedance of cab 2)
So, in our example: 8×4 / 8+4 = 32/12 = 2.67 (meaning you need a 2-ohm amp to drive the cabinets).
A calculation for using three or more cabinets of various impedances is even more complicated, but the only such combination that makes any sense in our opinion is to use 2x cabinets with 8 ohms impedance together with 1x cabinet with 4 ohms impedance. That will produce a 2 ohms total load.
For any other combination of cabinets with different load, here’s the calculation to find out the total impedance:
1/Total impedance = 1/Imp of cabinet 1 + 1/Imp of cab 2 + 1/Imp of cab 3…and so on.
The examples above are when the speakers are connected in parallel. All EBS speaker cabinets, no matter if you connect them one-by-one to the amps speaker outputs or connect one cabinet to the next and then to your amp, will result in a parallel connection. Some cabinets from other brands can also be connected in series. That requires a different calculation. We recommend you ask the manufacturer for details if you use such cabinets.
Make sure the power rating of your cabinet can handle the output of your amp.
Every cabinet has a power rating. This is not always written on the cabinet. On our website, you will find the specifications for each EBS cabinet.
If the power rating is expressed in “Watt RMS”, it means the continuous power that the cabinet can handle over time. If it only says “Watt”, check with the manufacturer if it means the continuous or peak output, and make sure you get the value for the cabinets continuous power handling.
Once you know the continuous power handling of your cabinet and using a single cabinet, we recommend that the value should exceed the amplifiers’ continuous output at the matching impedance of your cabinet.
So, a cabinet that can handle 300W RMS at 4 ohms, should not be used with an amp that produces 500W RMS at 4 ohms since that will mean a risk of damaging the speaker.
However, if the cabinet can handle 300W RMS at 8 ohms, it probably is safe to use with an amp that produces 500W RMS at 4 ohms, since the amplifier is then likely delivering around 250W RMS at 8 ohms. Did you follow?
The power output for the amplifier in RMS at 2 and 4 ohms is usually found in the manual or the specifications online. The output at 8 ohms is not always mentioned, but if you have the output at 4 ohms, you can roughly divide that by 2 for an estimation of what it will produce at 8 ohms.
If you are not sure about your amp’s continuous output, ask the manufacturer. Sometimes amplifiers are marketed with the peak value since that is simply a higher value that sounds more impressive to say, but it is more accurate to speak about the continuous output.
What about the power rating when using more than one cabinet?
When using two cabinets together, we recommend that the power rating of the weakest cabinet should at least match the amplifiers’ output at the total load that the combination of cabinets produces.
Any other concerns regarding power handling?
Yes, the power handling of a cabinet is reduced when reproducing extremely low frequencies. So, for example, when using a 5-string bass with a small cabinet, you need to be careful not to push the cabinet too hard. Same thing if you use extreme EQ settings and add a lot of low-end, especially with a smaller cabinet.
So, I got the impedance and power handling concept.
What is more to consider?
The experienced output of your bass rig is not only dependent on the power output of your amp. The physical appearance of your cabinets and the total area of the speakers involved contribute as well. The rule of thumb is the more volume (as in size) the cabinets contain, the more low-end they are capable of producing. And, the larger the total area of the speakers, the louder they will play as well.
Another important figure is the sensitivity of the cabinet, which is sometimes mentioned as the efficiency of the cabinet. It’s a huge difference in the output between a cabinet with a 95dB sensitivity and one with 105dB, even if they have the same power rating. A higher sensitivity usually means a louder cabinet at any given power rating.
The internal design of the cabinet and how it matches the speakers, as well as the porting of the cabinet are important factors too. Most EBS cabinets have a port on the front of the baffle, except for the ClassicLine 210 which is ported on the back.
!CAUTION! An important safety note.
We do not recommend using cabinets with only ¼” input jacks with an EBS bass amplifier. If you do, it is at your own risk.
When connecting a powerful bass amp to a speaker cabinet using ¼” contacts, you may get serious electrical shocks from touching the housing of the ¼” contact when it is connected to the cabinet due to the high voltage of the signal from the amp.
If you are forced by circumstances to use that, keep all equipment turned off until you have connected the speaker cab to your amp, and do not touch any metal parts or the contact on the back of your cabinet when the amp is turned on.
When possible, please use Speakon contacts at both ends of your speaker cable for your own and others’ safety.
Common questions:
How can an EBS ProLine 410 be rated to handle a frequency range of 70-18000 Hz and still sound good with a 5-string bass when the low B string’s foundational frequency is around 31 Hz?
The frequency range specified for an EBS cabinet relates to what a single speaker used in the cabinet is rated at. So, in this case, that means the rating of a single 10″ speaker in the cabinet. That means the total area of the four speakers and the size of the cabinet, which also contributes to the low-end handling, is not taken into account in the specified range.
Also, when you hit the strings on your bass, the string produces several overtones along with the foundational bottom frequency. Since the human hearing is weaker at lower frequencies, the brain has figured out ways to compensate for that. One is by using the information from the frequencies that these overtones produce to create an illusion of hearing the notes fundamental, lowest frequency clear, even when they are so low the human ear can impossibly hear it.
This is considered in the design process of an EBS speaker cabinet. The cabinets are designed to work in conjunction with how the human brain and hearing works, with extra attention to the reproduction of the low-midrange where the overtones appear. Instead of trying to compensate for the reduced hearing capability of low frequencies by boosting more low frequencies, which generally only produces rumbling noise that prevents a solid, audible, bass tone in the mix.
Why is EBS making the 1×12” cabinets in 8 ohms only?
A single 1×12” cabinet has some limits. One is the amount of power it can handle. To reduce the risk of blowing the speaker, and also to match the output volume with the size of the cabinet, we make them in 8 ohms only. That reduces the output of most amplifiers to fit the single 1×12 cabinet for an optimal sound and secure operation. Even at 8 ohms, we would not recommend the strongest amps (the EBS 802 or Reidmar 750) to drive a single 112 cabinet since the risk of blowing the speaker would be high.
Where can I find covers for my EBS cabinet?
Some EBS cabinets in the ClassicLine are delivered with a cover. These include the 810, 410, 212 and 210 of the ClassicLine series. Covers for the 112 ClassicLine (that also fits fairly well for the NeoLine 112) can be ordered through our webshop. It is also possible to order extra covers for the ClassicLine 410 & 212 by contacting EBS. For other models, we recommend external suppliers such as
http://www.tukicovers.com/amp-speaker-covers-bags/ebs in the US and https://www.amplifiercoversonline.com/ in Europe.