[aeromojito]

I have a pair of Ausdom M07 headphones that have decent sound except one thing. There is a big peak around 1500Hz with dips at 900 and 3600Hz. I have been toying with them and measuring with a makeshift mic and RTA. There is a 15dB difference between the dip and peak. Adding adhisive-backed felt inside reduces the peak by 2db and the dip by 3db but shifts them to 1kHz and 2kHz. The lows, highs, and 3600Hz dip are the same. Adding a round cotton pad raises the dip by 2dB and lowers the peak by 3dB but also lowers the low bass by 3dB. The biggest difference comes from removing the back completely. This smoothes the dip and peak so there is only a 3dB difference instead of 15. Im thinking the srivers may be better suited for open headphones. The problem is the headband attaches to the back of the cups. I would have to drill them full of holes to make them open. So how much of the back needs to be opened? Im not worried about isolation or leakage as these have vented earpads anyway.

 

[aeromojito]

Here is the FR graph from Ausdom. Mine is basically the same except the lows rise up to a higher 100Hz peak. I have noticed that some changes in sound don't change the measurements much. Cotton in the cups reduces the ringing effect but the response is only slightly different.
[ATTACHMENT=3956]20170113_212116.png (120k. png file)[/ATTACHMENT]