Looking for more tips/techniques to increase the passive noise reduction without changing the Fostex
cups or sound signature of the drivers. I've already found all the mods I need for the sound I like. Now
I just want to get them as close to noise isolating as my Pioneer Monitor 10.
These are the cup mods that I've tried so far:
1. Thin leather inside grills outer most part of cup
2. Acoustic absorbing Foam over the leather
3. Speaker Sponge over the foam (more for sound quality than isolation)
4. Plumbers Putty sealing and filling in all the gaps and open spaces to prevent reflections.
5. The stock supra-aural pleather on ear pads seamed to give the best bass and noise isolation.
I experimented with circumaural velour, cloth and pleather but none could match the stock pads.
For the size/shape of my ears and head, supra aural seems to create the best seal. The Pioneer
Monitor 10 is very close to supra-aural and its isolation is the best I've heard.
My measurements were completely subjective.
I found airplane pressure plugs that gave a rating of 22 dB reduction and compared them to some
other headphones. I had a high velocity 20 inch fan blasting to simulate the low frequency rumble
inside an airplane cabin. I tried to find reference documentation on the noise reduction specs of
my headphones, but none of the numbers seemed accurate. Beyerdynamic spec sheet pdfs http://www.manualslib.com/manual/215376/Beyerdynamic-Dt-150.html
showed 20 dB for my DT150, but they showed much less in my tests. Pioneer had no isolation
numbers. This website had some #s but they also seemed incorrect:
long foam plugs = 32 dB almost removed all of the fan noise
airplane pressure plugs = 22dB could still hear some fan
MEElectronics M2P-BK = 22 dB
Pioneer Monitor 10 = 20 dB
Modified Fostex T20v2 = 18 dB
Pioneer SE-30A = 18 dB can only hear fan on silent parts of music
beyerdynamic DT150 = 12 dB start to hear fan over less dense music
AKG K240 600studio =0 dB