Sony cordless headphones: TMR-RF850R and MDR-RF840RK.

Overall, very similar devices but with some significant differences in detail. The most annoying problem of the older set (TMR-RF850R) is the sudden white noise when the input signal disappears and the transmitter switches off automatically - it just blows my head!

On the newer set (MDR-RF840RK) this is fixed (and some other annoyances) but they have introduced another annoying feature (yes, build in features) - very bad and drastic sound level normalization. It is so bad that if you listen to a song the volume can noticeable fluctuate up and down! Also the max volume is so low that is not enough to drown some ambient noises...

As a very general conclusion - I would not buy again any of this headsets if I needed to.

TMR-RF850R

Mediocre design and sound quality.

Pros:

• loud sound
  
• comfortable

Cons:

• sudden loud noise when the signal disappears !!!
• extremely difficult to fit properly on the cradle !!!
  
• manual rotary channel tuning
  

MDR-RF840RK

Good design but mediocre sound quality.

Pros:

• very good design
  
• easy to fit on the cradle
• easy channel selection
• very quiet when the input signal is missing !!!
  

Cons:

• very bad automatic volume normalization !!!
  
• as consequence - not loud enough sound - I can easily hear ambient noises even on max !!!

Update: I have made a small movie illustrating one of the problem with the older set.




Specifications: MDR-RF840RK
Main Features:
* Transmission range up to 100m
* 40mm driver units for deep bass response
* Hassle-free recharging by placing the headphones on the dock (headphone charged via electromagnetic induction)
* Automatic On/Off for headphones making your batteries last longer
* Rechargeable Battery will keep the music going
General Data:
* Open Air Type: No
* Closed Type: Yes
* Dynamic Type: Yes
* Wearing style: Over band
* Driver unit (mm): 40.0
* Frequency response (Hz): 20 - 20,000
* Magnet: Ferrite
* Power ON indicator: Yes
* ON/OFF function: Power turns ON automatically when headphones are worn
* Mute function: Volume level decreases when RF signal is weak or not received
* Diaphragm: Pet
* Volume control: Yes
* Battery number: 2.0
* Battery type - normal: AAA
* Battery type - rechargeable: Ni-MH
* Battery life - normal (h): 28.0
* Battery life - rechargeable battery (h): 18.0
* Recharging time - from 0 to full (h): 16.0
* Weight (g): 300.0
Transmitter:
* Transmission type: RF
* Signal range (m): 100.0
* Charging stand type: Standing
* Battery charge method: Automatic
* Battery charge indication: Yes
* Power ON indicator: Yes
* Distortion rate (% at 1 kHz): <1
* Transmitter frequency range (Hz): 30-12,000
* Transmitter power ON/OFF: Signal transmission starts when audio signal is detected
* Available channels: 3.0
* Stereo mini jack input: Yes
* RCA jack input: Yes
* Weight (g): 220.0
Supplied accessories:
* AC adaptor: Yes
* Rechargeable battery: Yes
* Connecting cords: Yes
* Plug adaptor: Yes
* Dimensions:
* Width (mm): 112.0
* Heigth (mm): 245.0
* Depth (mm): 310.0
Please be aware that the features/specifications can differ from country to country.