[BigAund]

hi,
 
I recently bought a set of Mb Quart 805 Demo phones from Ebay - they are the ones that used to be used for listening stations in HMV, Tower records with an armoured cable etc... I was sold them as being 100 Ohms but in the process of removing the armour from the cable I had to remove and resolder and in doing so noticed some markings on the driver - see picture:
 
 

 
You can see the driver is marked with 400Ohm and 0.1W - what does the 0.1W imply, something to do with sensitivity? I understand about the Ohms but not the rest - Can anyone help?? Also I don't know if the marking 50F (on Left) has any relevance?
 
I have used these with my iphone 4 and Fiio E6 - its not the loudest but I like it.
 
Many Thanks
Aund

 

[Gwarmi]

 
 
Are they marked anywhere on the headphone as being 100ohm? ~ this model I believe came in
300ohm and 400ohm variants.
 
This for example being the 300 ohm.
 

 

[BigAund]

No markings at all apart from those on the Driver - I think they may have been OEM and re-badged as they aren't marked as Mb Quart or any other brand.
 
Do you know what the 0.1W on the driver means?
 
thanks

 

[Gwarmi]

Quote:

No markings at all apart from those on the Driver - I think they may have been OEM and re-badged as they aren't marked as Mb Quart or any other brand.
 
Do you know what the 0.1W on the driver means?
 
thanks

 It appears that the 0.1W would be related to the headphone's sensitivity ~ plenty of folk on here with
 superior mathematical skills to my own, but this appears to be the case in order to give the
 headphone's actual SPL.
 
 

Sensitivity

Sensitivity is a measure of a transducer's output when driven with a specific reference input.

Headphone manufacturers often loosely use the term "efficiency" where sensitivity should be used.

Headphoneefficiency (power in/power out) is a type of sensitivity, but efficiency is usually not an

important characteristic to measure for headphones (see Efficiency vs Sensitivity).

Common "units" for headphone sensitivity are "dB/mW" and "dB/mV".

This notation is an inappropriate simplification,^[5] but what these mean are dB SPL (sound pressure level)

measured in a standard ear for a 1 kHz sinusoidal headphone input of either 1 milliwatt or one millivolt.

Technical notation would be "dB ref. 20μPa/mW" or "dB ref. 20μPa/mV".

One can convert between these two references if the impedance is known.

 

[zeno]

Looked up some info online....
Apparently that is the maximum power input....For example my AKG K340s are...
 
Maximum Continuous Input (per chan.): 9V (200mW) approx. 117 dB SPL
 
The ones in question here are 100mWs.