So I have asked questions about amps,,but I have seen it said here many times that the cabinet design/ efficiency is critical. So I have to ask which cabinets are considered to be if great design/ efficiency. I am specifically curious about Markbass,being that’s what I see most often in Guitar Center,and in FB Marketplace..They make some very light 4x10 cabs and Inwonder if they are good or not..Love to hear your thoughts.
Markbass specs are generally pretty good and the gear is widely considered to be quality.
First I will say, the specs are not a perfect indicator of performance, partly because there is no standardization in the process for developing specs. IMHO specs are most useful for comparing cabs within the same product line. When comparing cabs across product lines they may not be as useful. Why? The way specs are developed across product lines may vary. When comparing specs across brands, the specs are ballpark estimates at best.
The spec that relates to efficiency is Sensitivity. Most commonly with bass cabs, Sensitivity is expressed as the SPL measured at 1 meter when 1 Watt is applied. For example:
- Sensitivity = 97dB 1W/1m.
This says 1 Watt is applied and 97dB is measured at 1 Meter.
When you double the power, you expect a 3dB increase in SPL.
- 1W = 97dB
- 2W = 100dB
- 4W = 103dB
- 8W = 106dB
- etc
You can use the Sensitivity rating and the 3dB rule to do an estimate of how loud a cab can play at rated power. Use RMS or AES power ratings. Do not use Program or Peak power ratings.
For example let's say your amp has a 250W power rating. If we continue our sequence we get:
- 16W = 109dB
- 32W = 112dB
- 64W = 115dB
- 128W = 118dB
- 256W = 121dB
Since our amp is rated 250W, the rig is a few watts shy of the power required for 121dB calculated.
Speakers develop power compression as the approach performance limits. So at some point you start to get less then +3dB when you double the power. Therefore real world SPL will tend to be a bit lower than calculated SPL.
If you know the 1W sensitivity and the RMS or AES power rating, you can estimate how loud the cab can play using the following formula:
- Calculated SPL =10Log(Power) + Sensitivity
Let's assume our speaker is rated for 400W RMS and the Sensitivity is 97dB 1W/1m.
- Calculated SPL at rated power = 10Log(400) + 97 = 123dB
This is an estimate of the max SPL the speaker can produce based on the RMS power rating.
With our 250W amp
- Calculated SPL = 10Log(250) + 97 = 120.97dB
Other Useful Info
- If the Sensitivity is based on 2.83V, you have to consider the impedance. 2.83V at 8 ohms is = to 1W. So 97dB 2.83V/1m at 8 ohms is the same as 97dB 1W/1m. However, 2.83V at 4 ohms = 2W. So you need to subtract 3dB to get the 1W/1m rating. 100dB 2.83V/1m at 4 ohms = 97dB 1W/1m
Normally extension cabs are connected in parallel. So when you add a matching cab: combined impedance = 1/2, combined power handling = 2X, combined sensitivity = +3dB.
We have one speaker rated 400W with Sensitivity = 97dB 1W/1m. Let's assume it's an 8 ohm cab. For a pair of the cabs connected in parallel:
- Combined impedance 1/2 of 8 = 4 ohms
- Combined handling = 2 x 400 = 800W
- Combined Sensitivity = 97 + 3 = 100dB 1W/1m