How to achieve awesome mid bass
I have recently received many questions about mid bass. Instead of making several replies I have opted to make this post. Questions and additions welcome.
This is one of the most complex and misunderstood topics in car audio for the following reasons that I will explain.
1. Phase
You must be able to grasp the concept of sound in the incremental phase domain as well as sound in the frequency domain. I will explain.
2. The cars dimensions
The car itself conflicts with good mid bass response do to various interior dimensions of a typical automobile coinciding with the physical size of sound waves in this frequency range.
3. The misconceptions
The misconception that poor mid bass is due to low amplitude in this range. More won’t help. I will explain.
4. Futile attempts
Many of the attempts people make to increase mid bass response only make it worse including gaining up, expanding crossover pass band, adding more speakers, and placing the mid bass drivers in an enclosure.
The term mid bass can be interpreted many ways. In car audio however this band is pretty much set as the band between 50hz and 250hz. This is due to many reasons that are beyond the scope of this article. What’s important to understand is that in the 50hz-250hz range humans are the very least sensitive to variations in frequency response but we are the most sensitive in this range to changes in phase. As frequency rises above 250hz the opposite becomes true. Humans become less aware of phase response and much more aware of frequency response.
Phase
Phase is the angle measured at a given point on a sound wave.
Here you can see that from where Homer sits the sound wave arrives at his ear at one angle but below you can see that when he changes is position relative to the speaker the angle of the sign wave changes as well.
he can’t hear any difference in the sound. But when you add a second speaker things change.
Now his brain is picking up one sound coming from two different places. His brain knows its coming from two different places partially because the phase angle is not the same. When this happens your brain will red flag this sound information as “invalid