Headphones and Earphones
- Written by John E. Johnson, Jr.
- Published on 18 July 2011
On the Bench
As with our previous earbud and headphone reviews, I put the NuForce NE-700X earbuds through our bench tests. The microphone was connected to the earbud through a 1/2" section of surgical tubing. That is about as close as I can set the test up so that it mimics the ear canal. The volume was adjusted to 90 dB for the tests.
At 20 Hz, distortion was less than 2%, which is excellent.
At 1 kHz, distortion was less than 1%, also an excellent performance.
And, at 10 kHz, again, less than 1% THD+N.
IMD was the lowest I have ever measured for this type of product, and low IMD is critical to good sound. It means you get lots of detail and no smearing or muddiness in the sound, and that was exactly my experience. At $65, no wonder they are a best-seller on Amazon.
For the frequency response, I illustrate the spectrum beginning at 100 Hz so as to make the high frequency portion of the graph easier to see. It shows the typical rises and dips that we have seen with all earbuds. I suspect that it is due to the driver being so close to the eardrum, and the sound bouncing off the walls of the tubing, causing cancellation and augmentation. Note that the same pattern of response is shown when exact models of the human ear canal - including material that simulates human skin - are used to measure frequency response of earbuds, so it is not because I am using surgical tubing.