This is a pair of dynamic drivers used in Monster Turbine Pro earphones offering super heavy bass. See below video about the review of this $400+ earphone:
2 pieces of front cover spacer (for air sealing in installation)
Measurement is done by an IEC711 coupler, a customized USB sound card and Win10 PC running ARTA software.
Open Space measurement – meaning the install the driver only to the front cover, and leave the back end open to free space.
Frequency response (open space): notice the bass and sub-bass bands are boosted 5dB, and well extended to 20Hz! This is where the super bass coming from!
Impulse response (open space)
Cumulative Spectral Decay (open space) – note even with super bass, the 300-1kHz band has very consistent decay, meaning the bass is clean and won’t interference other bands.
Burst Decay (open space)
Close space measurement with IE800 shell– meaning the install the driver is fully installed in to Sennheiser IE800 shell .
Frequency response (close space) – notice the bass going even higher after being installed in shell, others band are not impacted.
Impulse response (close space)
Cumulative Spectral Decay (close space) note the decay getting more consistent after being installed with shell.
Burst Decay (close space)
Frequency response with different earpads and positioning
The driver by itself is very balanced and fine tune won’t be necessary. this section helps you to understand the impact of earpad and its position on the frequency response. See following curve – Red curve is when using a sponge earpad while loosely inserted, you can see the lose on bass due to leakage; Green curve is sponge earpad and correctly positined; Blue is a silicon rubber earpad, you can see it seal the ear canal better and not only boost bass, but also increase the variance at treble – see 8kHz and 12kHz.