[SSandDigital]

A990Z has some flubby bass because of the Double Air Dampening System.

What is Double Air Dampening System?
Audio Technica surround the driver with a plastic cage. There is a doughnut shaped large piece of foam inside the cup. The cage then rests on top of the doughnut shaped foam, which creates a second chamber. Hence the Double, and the air dampening being made from foam my guess.

How does a boutique headphone designer dampen his headphones? I looked up how ZMF dampens his headphones. He uses antislip foam against the cup. And then outside rim of he uses some sort of dampening foam, it's not dynamat. And he uses some sort of fiber filling that I see used in vintage speakers.

My plan, will order ballistic acoustic dampener.

See pics below to see what I did to just experiment with this idea:

My findings: It's a start. I already prefer the sound of this over the DADS bass system. I think will be improved once I get acoustic dampening material for the outer housing rather than foam and some poly fiber filler.

 

[SSandDigital]

Round Two!

Goal:
- Control the bass. Bass monsters.
- Control the resonance from bass was hearing, and ringing from treble.
- Get rid of the hollowness I heard.

Materials Used:
Ballistic acoustic dampening
Simple Foam Cushion from Michael's craft store

Method:
- Placed ballistic around the circumference of the headphones
- Small pieces of Ballistic around the driver cage
- Ballistic essentially anything plastic.
- The final I just placed a large round piece of the white foam into the cup.

Success?
- Testing with various genres of music, such as Jazz, Trance, Metal and OST, Orchestral
- Yes I think so. The bass is tighter. The hollowness is gone. The SS is maintained. The ringing from the treble is definitely gone.
- I did this all by ear, I don't have measuring equipment. I tried to get these to sound as close to the JBL L20T3 speakers. With obvious limitations to a closed headphone, I think I succeeded.

Do I recommend?
- Yes I definitely recommend experimenting. I have no idea how they measure, this is just by my ears, but I believe A990Z needs some help.