Howard.Gayle@cmu-cs-g.arpa (08/16/84)
I had a chance to compare a David Clark H10-40 headset with a Telex E-951 on a long trip, including flights of 4 hours with each headset. The Clark had foam ear seals without cloth covers. Both sets have electret mics. Noise reduction: Clark wins. It was noticeably quieter. However, the Telex was quiet enough for the airplane (Warrior) and the amount of flying I normally do. I never noticed any ringing or deadness in my ears, even after 4 hours with the Telex. Construction: except for the mic boom, the Clark seems extremely well built. For example, the plugs look gold plated, and the wires are crimped onto terminals which are then screwed to the plugs, rather than just being soldered. The mic boom, however, looks rather kludgy, as if it were added on to an earlier headphone-only design. The Telex looks flimsier, but in practice didn't give any trouble. The Telex mic boom can be rotated so that it can be used on the left or the right. Mic quality: the Clark mic is very small, and is subject to a lot of wind noise from cabin vents or an open storm window. When worn close to the mouth, for maximum noise reduction, it pops whenever the wearer speaks a plosive consonant, like p. This can be corrected by moving the mic farther from the mouth, but then noise reduction suffers. The Telex mic does not have these problems. Comfort: Wearing the Clark was like having my head in a vise. All the weight was concentrated on a small point at the top of my head. I got a headache after a long flight. It was constantly slipping and needing readjustment. The Telex was much more comfortable, with the weight distributed more evenly, though it also slipped to some extent. Weight: Telex is lighter. Conclusion: I'll take the Telex. A headset does no good if it's too painful to wear. The Telex has enough noise reduction for the kind of flying I do, and if I needed more I'd look first at the Telex deep muff D-1040/E-1041 (I think) series. Of course, headset evaluation is subjective. Everyone has a different head, and does different flying.
mlf@druxv.UUCP (Fontenot) (08/17/84)
One word of warning about the Clark: if it's too tight, and you try to ease the pressure by spreading the earphones apart, it can break (guess how I found out). I think that a small portion of the metal strap (midway between the earphones) has been heat-treated and can be bent, but the remainder of the strap is very brittle. If you must bend it, try to apply pressure only at the midpoint of the strap.