Besides sharing our subjective impressions with you, we want to give you some objective data. We measured the frequency response and sound pressure of the headphones by means of an audio analyzer Euraudio PRO600S with the default calibrated third-octave microphone. The measurements were performed on pink noise at a maximum volume of the headphones outputs of the semiprofessional audio interface E-MU 1820. The microphone was wrapped into a thick layer of foam rubber and pressed against the headphones’ ear-pad.
So you can note a very deep and flat bass smoothly connecting to the bottom middle. There is a reduced section at the joining point of medium and high frequencies, and a sudden rise at a range of 5-8kHz, which is noticeable to the ear. Anyway, the frequency range and sensitivity of these headphones is very good.
Here, we can see an undulating diagram with a stress on middle bass and the middle of the high-frequency range. This must be a feature of all Grado products. The minor rise in the top middle adds a slight coloring to female vocals and to the sound of many musical instruments while the slump at 4kHz explains the rather narrow scene created by these headphones and, probably, the lack of stress on vocalists’ smacking sounds. These headphones are over 3dB inferior to the junior model in terms of sensitivity, yet it is more than enough for any application.
The frequency response of the Sennheiser HD 600 is a treat to the eye even though it differs from the curve you can see at the manufacturer’s website.
A separate diagram with the difference in frequency response between the Grado SR325i and Sennheiser HD 600 helps avoid the irregularity of the measuring equipment and show the difference between the two models. The diagram is constructed with a step of 1dB. Blue marks the advantage of Sennheiser, red marks the advantage of Grado.
The increased middle, the more emphatic bass and the specific high frequencies of the Grado headphones become apparent. Note that the frequency response of the two headphone models almost coincides in the medium-frequency range except for its top octave.