[Sonic Defender]

This request is for those head-fi members who just love figuring out audio puzzles. I think I have a very audible example of either (a) impedence mis-matching between source and headphone, or (b) the effect of mechanical damping/low impedence design. This is a little difficult to explain so please bare with me.
 
I have found a Sarah McLachlan song (Into the Fire) from her album Solace that with low impedence headphones (confirmed on my HF2s and DT 770 80 ohm) that at a particular passage repeated throughout the song seems to cause a very distorted bass response generated from a sub-bass signal. However, when I play this same song through my DT 880 600 ohm headphone, regardless of the source (Valhalla, Creek solid state amp, iPod video+E11) the sub-bass signal is smooth and full. There is nothing wrong with either of the low impedence headphones, and playback volume was not an issue.
 
If anybody is interested in replicating this the sub-bass pulse occurs as the chorus begins with Sarah singing the line "and into the fire...". There is at least one other instance besides the chorus where this sub-bass pulse happens which will also trigger the distorted response. There is no doubt that the high impedence 880 makes it through the passage without a hitch which leads me to suspect the reasons I listed above for the low impedence headphone issue, either the result of a signal high-lighting impdeence mis-matching, or as I take it, the related effect of using more mechanical dampening. I know it is a strange request, but I do not enough about the science of sound to understand what is going on. Thanks for any thoughts you might have on this trivial, but interesting observation of mine.

 

[stv014]

It would be better to make the comparison with the same headphones, but different (level matched) sources, or the same source with or without an impedance adapter. Maybe the DT880 simply has better bass response with lower distortion than the others ?
 

 

[brod]

Quote:

At least for the DT770 I can confirm that it is prone to bass quality related problems.

Can you elaborate on this please? What problems does the DT770 have, and are you referring to all models or just the older 'pro' versions?

 

[stv014]

Edit: removed as not really relevant to the topic
 

 

[Sonic Defender]

I must confess ignorance of how dampening actually functions. I had always believed that dampening while helping in some respect, actually degregated sound quality. Are you able to elaborate on the information you have presented in how it relates to my question? Or, are you able to suggest a good learning resource instead? Thank you for taking the time to banish the clouds of ignorance from my mind!

 

[stv014]

Well, you mentioned having problems specifically with low impedance headphones, so I thought damping may be an issue at least to some extent. A high damping factor (voltage source) does reduce transducer distortion compared to a low one (current source). Although it is not a large difference, so I admit it may not be the real explanation in your particular case, therefore the information I posted above was not really relevant. Perhaps the DT880-600 is simply a better headphone than the other ones. The ability of dynamic headphones to reproduce loud bass with low distortion does vary significantly.
 

 

[shadow419]

Re-posting this here :
 
 
Strange indeed, since the E11's output impedance was measured by Voldemort as 0.5Ω.  On my Incipio f38's (32Ω) I can hear the passage you're talking about fine and without any distortion.  HD 25-1 II's (70Ω) barely even register anything, but not surprised since sub bass is a weakness on these. 
 
edit: This is from my home pc w/ O2 amp.

 

[stv014]

I should have read the OP more carefully, if the DT770-80 distorts with the E11, but the DT880-600 does not at a similar loudness, then that is clearly a problem with the headphones and is not related to impedance. It is either just worse than the 880, or maybe there is hair or other debris in the drivers.