Sennheiser 4.50BTNC audio cable sound quality

[denial1976]

Well, I use these headphones for few years and when deciding which model to buy, beside my individual sound quality range, i wanted the ones which came with the availability to connect by audio cable, so I could use them on my old before-bluetooth-era devices.

So I fetched the above mentioned model, and while using it via bluetooth connection everything seems fine, but while connected by audio cable, sound seems weak, thin, low frequencies dissapear, something like additional amplifier is missing. So far I tried to use headphones on the smartphone and with Sony D-CJ01 portable CD-R/RW player. On both devices I received the same weak sound.

Am I doing something wrong or that poor sound should be due to some failure? Honestly, headphones are bought as used and that jack seems somewhat wobbly.

 

[unpluggged]

This is normal for this kind of headphones. They rely on heavy DSP to sound decently, and in passive mode they often sound bad.

See this for example:

 

[solderdude]

Well, I use these headphones for few years and when deciding which model to buy, beside my individual sound quality range, i wanted the ones which came with the availability to connect by audio cable, so I could use them on my old before-bluetooth-era devices.

So I fetched the above mentioned model, and while using it via bluetooth connection everything seems fine, but while connected by audio cable, sound seems weak, thin, low frequencies dissapear, something like additional amplifier is missing. So far I tried to use headphones on the smartphone and with Sony D-CJ01 portable CD-R/RW player. On both devices I received the same weak sound.

Am I doing something wrong or that poor sound should be due to some failure? Honestly, headphones are bought as used and that jack seems somewhat wobbly.

I have seen quite a few BT headphones that apply some form of EQ that differs when using the wired input and BT reciever.
So they do not have the same tonal balanced when used with BT.
There are also plenty of BT headphones that do not do this and sound 'similar' in both modes (except for volume).

I have not measured the 4.50 so don't know if this is the case here too but reckon some form of EQ is used in the BT signal path as most will be using it this way.
The 'analog in' is usually just for convenience. Add to that in a lot of cases that analog input won't even work when the battery is dead. There are a few that can be used in 'passive' mode where the analog signal is routed directly to the internal speaker and not through the internal amplifier.
In those cases the sound signature will be quite different but at least you can still use it this way.