Sony MDR RF4000K Specifications, Tests and Review

The wireless headphones Sony MDR RF4000K allow unrestricted movement, which increases the comfort of using the headphones. This feature is particularly popular with headphones for casual use. However, a certain limiting factor of wireless headphones compared to wired ones is a certain delay in sound transmission between the source and the headphones (but almost indistinguishable for the average user) and the need for regular charging. Unlike wired headphones, wireless headphones are charged separately. The transmission range offered is up to 30 m. The maximum range represents the maximum distance from the audio transmission source that the headphones can be used for wireless audio transmission. However, the maximum communication range can be affected by obstacles such as people, walls, etc.

This type of headphones has a design that surrounds the entire ear to improve isolation from external noise. As a result, they provide a great quality of listening without interference. However, unlike on-ear headphones, they are usually heavier and less suitable for frequent wearing. The weight of the headphones is 300 g.

The sound quality can be affected by many factors. When it comes to frequency range, a wider range will allow more detail to be heard during your listening session. However, it is important to note that the ability to perceive frequencies varies from person to person. The average person is able to hear frequencies in the range of 16 to 20 000 Hz. That is why headphone manufacturers usually focus on the 20 to 20 000 Hz range. If the lower values are lower, headphones are better able to reproduce bass tones, as these represent frequencies up to approximately 256 Hz. Conversely, values from 2 048 Hz upwards are treble. Thus, headphones with a high upper limit will provide a much more accurate reproduction of high tones. Headphones Sony MDR RF4000K have a frequency range of 10 - 22000 Hz.

The headphones are composed of many various components, one of the most important is the diaphragm. Diaphragm transforms the electrical signal into sound and therefore its quality affects the overall listening experience. There are three types of diaphragms: thin, medium-thick, and thicker. A thin 6 mm thick diaphragm responds quickly to high frequencies but less sensitively to bass. The medium-thick 10 mm diaphragm provides a balanced sound profile, allowing you to enjoy both bass and treble. The thicker 20 mm diaphragm is more sensitive to higher frequencies but has a poorer bass response. These headphones are equipped with the 40 mm.

These headphones have a battery capacity of 550 mAh. In terms of headphone battery life as a significant factor in the purchase decision, it depends on what you want to use the headphones for and potentially how often you will be able to recharge them. Headphones with up to a few hours of battery life are more suitable for home use as they will require more frequent charging. Headphones with a battery life of around 10 hours or more are already more suitable for commuting and shorter journeys. However, nowadays you can also find headphones on the market that have a battery life in the higher tens to hundreds of hours. In this case, you do not have to worry about your headphones simply running out of power on longer journeys, and you will not have to deal with constant recharging. The battery life of the Sony MDR RF4000K reaches up to 10 hour(s).