Feel free to ask questions. I'll do my best to answer.

Friday, May 24, 2013

Beyerdynamic DT770M

This is my first measurement of these phones:

It disturbed me that the difference in the bass was so large--the left side has ample deep bass, the right side doesn't.  So I decided to do a little investigation.

First I took the headphones apart to measure the raw driver.  You can see I was unable to hold left side tight to the measurement rig b/c the wires are fastened pretty close to the housing and I have no desire to try to solder these again.
From this point forward, the red line will be the right, the left line will be in blue.  Anyway, the raw driver measurement doesn't show anything to be concerned about. Good news I thought.

Next I put the drivers in the housing without damping material just to see what would happen.
Eureka!  There's are bass problem.  So I was hoping it was just some problem with how the driver was seating in the cup.  I removed them both to add the damping material (plus an extra cotton ball), and sealed every potential air leak I could find hoping that the reseating would fix the problem.
Not exactly, but it did remove that 6kHz notch. :)

Ready to surrender for the day, I put the stock pads back on for another measurement to see how it might compare to the first measurement:

The extra cotton definitely changed the bass tuning a bit and changed the shape of the treble response.  I'm guessing the time domain would look a little better b/c of that.

Next I held them loose on the measurement rig to see what effects the seal has.
I contacted Beyerdynamic to see what they think and how to get it fixed.  Let me know if you have any suggestions.  I'm stumped.

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