Sennheiser HD 222 Headphones Review

Sennheiser’s reputation as a manufacturer of high-quality stereo headphones was established largely by their pioneering work with non-isolating headphones— which they call “Open Aire.” The ear cushions of these phones rest lightly on the ears and do not attenuate outside sounds. Although special design techniques are required to develop a uniform low-bass response from phones that do not seal around the ears, as a class they are much more comfortable to wear than conventional circumaural or sealing-type headphones.

Recently, Sennheiser has added circum-aural phones to their product line. The newest is the HD 222, which weighs only 9 ounces (exclusive of the cord and plug). Its foam-filled ear cushions surround the ears, providing considerable isolation from outside sounds, yet they are so soft and comfortable that one does not have the feeling of pressure and weight that is typical of so many sealing phones. The molded-plastic headband has an adjustable inner vinyl strap that fits around the head and distributes the already light weight of the phones over a large area so that they can be worn for extended periods without discomfort.

The earpieces contain dynamic transducers with a rated impedance of 600 ohms. The German-made HD 222 phones are rated by DIN standards to deliver a sound-pressure level of at least 94 dB for an input of 1 milliwatt (0.77 volt). The maximum continuous-input rating is 0.2 watt (11 volts). The harmonic-distortion rating by DIN standards is less than 0.1 per cent.

The Sennheiser HD 222 phones have a lightweight, straight (uncoiled) 10-foot cord fitted with a molded plug. The suggested retail price of the phones is $120. An accessory 10-foot volume- and balance-control cable is available for $22.20.

Laboratory Measurements

Our headphone test coupler is essentially identical to the standard ANSI type, upon which a pair of headphones can be mounted as on a wearer’s head. A calibrated microphone inserted behind one “ear” cavity measures the sound-pressure level created by that earpiece. The frequency response of the HD 222 phones was measured with a drive of 0.77 volt, equivalent to 1 milliwatt into its rated 600-ohm impedance. The bass and lower-midrange output was good, varying only about ±3 dB from 20 to 400 Hz. Above that frequency the output dropped off smoothly to a minimum in the 1,000- to 5,000-Hz range, where it was roughly 10 dB less than the average bass/midrange value. The output then increased sharply above 5,000 Hz, reaching a maximum at 10,000 Hz before falling steeply at higher frequencies. The maximum high-frequency level was about the same as the highest low-frequency reading. This sort of frequency-response measurement is not unusual in headphones, since it reflects the characteristics of the coupler as well as those of the phones.

The average sound-pressure level below 400 Hz was 97 to 98 dB. We also measured the sound-pressure level at 1,000 Hz, with the 0.77-volt drive level, as 90 dB. The impedance was an almost constant 600 ohms (as rated) across the audio range.

The harmonic distortion of the headphones’ acoustic output was measured at frequencies of 20, 1,000, and 5,000 Hz, using a number of input voltages up to 12 volts. At middle and high frequencies the distortion was very low, ranging from 0.2 to 0.5 per cent at inputs from 0.1 to 12 volts. The latter, which is slightly higher than the maximum continuous-input rating of the phones, produces a very high sound level, more than 110 dB in the midrange. The 20-Hz distortion was only slightly higher, measuring between 0.6 and 1.4 per cent over the same range of input voltages.

Comment

The test data confirm that the Sennheiser HD 222 has very low distortion, more than adequate sensitivity, and a very good bass response. Since the frequency response measured on a headphone coupler is certain to be different from that existing in a human listener’s ears with the same phones, we listened at length to the HD 222 with different types of program material, comparing its sound with that of other phones with which we are familiar.

First, we must say that these were among the most comfortable phones (of any type) that we have ever used. In many respects we found their soft cushions to be more comfortable than most open-air phones we have worn. One has almost no sense of wearing phones; there is no pressure on the top of the head or on the ears and none of the feeling of confinement that so often results from extended headphone use.

The sound, to our ears, tended to be somewhat “bottom heavy." If the program had lots of highs or was artificially brilliant, the balance of the HD 222 often improved the sound and made it most listenable. On the other hand, if the program was lacking in highs, as in AM reception, the result was often a rather dull quality. The excellent low-bass response of the HD 222 also made it a most revealing indicator of the presence of 60- or 120-Hz hum in the audio signal (this is often a problem with high-quality sealing phones, but rarely with open-air types). On the positive side, we found that the HD 222 could play at high volume levels without significant audible distortion at any frequency and with a worthwhile degree of acoustic isolation provided by its sealing ear cushions.

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