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Beyerdynamic DT 931 Headphones&lt>Introduction&lt>Beyerdynamic has long been a name synonymous with headphones. They were in fact the first company to develop a pair of dynamic headphones with their DT48 back in 1937. The DT 931 is currently Beyer’s flagship pair of headphones which combines their years of experience in both the hifi and professional market.&lt>Beyerdynamic was established in 1924 by Eugen Beyer. Eugen constructed some of the first amplifiers and loudspeakers for film applications when sound was first being introduced into cinemas. He has also been credited with designing the world’s first dynamic headphones and the world’s first dynamic interviewing microphone. Beyer currently produces a whole range of professional and consumer microphones, headphones and conferencing systems which are respected the world over.&lt>Specifications&lt>Headphone Type: Utilizes dynamic transducers based on an open circum-aural principle.
Frequency Response Range: 5-35,000Hz
Nominal SPL: 96dB
Nominal Impedance: 250 ohms
Total Harmonic Distortion: = 0.2%
Weight (without cable): 295g
Headband pressure: ~ 2.5N
Termination: 1/8” Gold Plated Stereo Jack Plug (a 1/4” stereo jack plug screw in adaptor is included)
One Year Limited Warranty&lt>These headphones’ specifications didn’t differ greatly from the rest of the headphones seen in this review. It featured the same open, dynamic and circum-aural design principles as seen in all other headphones except for the Grado SR325 which sports a supra-aural design. The only specification which really sets it apart from other headphones is its amazing frequency response. The frequency response range on the DT931 is truly remarkable. It is definitely the widest range seen in this review.&lt>The 250 ohm impedance of the DT 931 definitely requires some form of amplification. I have tested these headphones without an amplifier utilizing a portable CD player and acceptable volume levels can be achieved but sound quality is severely degraded to the point where it’s not worth using them.
The nominal SPL rating on the DT 931 puts it on par with others in the test. It’s 2dB lower than the Grado unit and 2dB higher than the AKG unit. Although, the 931’s SPL isn’t as low as Ultrasone’s published figure of 90dB, Beyer’s 96dB SPL shouldn’t be cause for alarm.&lt>The THD was a welcome addition to the list of the DT931’s specifications. We can see that their quoted figure of 0.2% is very low which theoretically gives minimum distortion or coloration. &lt>The weight of this unit was about 40-50g heavier than other units seen in this review. Whilst 295g is hardly heavy, keeping weight to a minimum especially in a headphone design usually makes the unit more comfortable especially over extended periods of time. The rest of these headphones’ specifications including their warranty period and termination were standard and didn’t differ greatly from other units in this review.&lt>Features<P>These headphones feature high gauss neodymium magnets, computer aided design (CAD) ear cups, a new diaphragm material, coiled cord and patented “breathable” viscose ear pads.<P>The DT931’s magnet system also features precision coil winding to allow for more detailed imagery and reproduction. This also helps to give the DT931 it’s amazing frequency response and neutral tone.<P>The CAD ear cups were the other component responsible for the DT931’s amazing frequency response. They have been custom designed to offer the greatest frequency response whilst minimising distortion and coloration. Judging by the frequency response graphs they have largely succeeded in achieving this.<P>The coiled cord and viscose ear pads form some of the comfort features of these headphones. Viscose is actually a type of rayon; it is silver/grey in colour and feels similar to velvet. Beyer made the unusual step of including a coiled cord with the DT 931. Whilst this cord design may seem handy and quite tidy at first it becomes more of a hassle if extra cord length is required.<P>Finally, this unit also featured a double headband design with separate left and right locking adjustment mechanisms. The double headband features an adjustable inner headband constructed of a soft material (similar to felt) connected to an outer headband which is constructed of sturdy plastic. This design ensures that the listener receives maximum comfort with no build quality compromise.<P>Build Quality<P>The DT931 headphones have an all plastic construction. The outer headband on this unit was constructed of extremely sturdy plastic which seemed stronger than both the HFI-2000 and the K 501. As stated above the outer headband has a purely structural function and lends nothing to the unit’s comfort. Keeping this in mind, Beyer opted to make the outer headband as strong as possible with no regard for comfort as it does not come in contact with the listener’s head.<P>The unit’s ear cups are made from similarly sturdy plastic with Beyer’s durable viscose material on the inner side. The swivelling mechanism on this unit was also sturdier than that seen on other units in this review. It features two plastic semi circular posts which are attached to the unit’s main outer headband. These semi circular arms have a locking design on their ends which allow them to secure the ear cups firmly whilst still making it possible for a user to remove the ear cups for pad replacement if necessary. Most other ear cup swivelling mechanisms simply locked with the ear cup at the point where it met with the headband. This design was sturdier because it attached the headband to the ear cup via two points instead of the standard one.<P>The double head band design also allows the user to easily replace the inner headband should it become soiled/damaged or worn out. This was a far better option than other headphones which either have no padding or offer padding which is not easily user replaceable.<P>Comfort<P>These headphones proved to be very comfortable but were not quite up to the comfort levels offered by the AKG K 501. The main problem of comfort stems from the DT931’s ear pad design. Although Beyer has attempted to keep their ear pads “breathable” I still found that heat buildup became an issue after several hours of use. There was simply not enough air circulation inside the pads to keep the ear cools during long listening sessions. This was no doubt due to the viscose material’s tendency to retain heat. The velvet found on the Sennheiser’s HD 600 and the material found on the K501 did a far better job of allowing air to circulate inside the ear cups. Apart from this Beyer’s ear cup design was very spacious and well padded which made the headphones quite a comfortable experience. They were definitely not as uncomfortable as ear pads found on the SR325 or HFI-2000 headphones.<P>Beyer’s head band design was also intelligent with a space between the inner and outer headbands allowing for ample air circulation. This ensured that there was no potential heat build between the two headbands. Adjusting the head band size on this unit was not as easy as the simple push/pull mechanism found on the Sennheiser and Grado Labs units nor was it as easy as AKG’s self-adjusting head band. It did require the user to remove the headphones from their head to adjust the locking mechanism which controls the inner headband. I found this headband design to be slightly more troublesome than the others featured in this review but it should only need to be adjusted once.<P>Beyer’s connecting cord also proved to be another source of concern. First off, Beyer chose to attach the connecting cord to both ear cups which can be cumbersome. Although this practice is not uncommon it would’ve been nicer to see a single sided connecting cord as found on the HFI-2000 and K 501.<P>Secondly, the connecting cord is coiled similar to a telephone handset cord. This poses a big problem if you intend to use anywhere near Beyer’s advertised 3M cord length. I found that the connecting cord starts to pull on the headphones after about 1.5M of cord which is a great hassle if you like to sit further away from your components. These headphones are also quite light at 295g so the cord’s pull can quite easily dislodge them from your head which places the drivers in a less than optimal position. At worst, if you have a slightly smaller head it would be quite possible for the connecting cord to pull the headphones straight off your head which could potentially damage them. I found this cord far more distracting than that found on the Grado Labs unit as my components are situated some distance from my chair. I found that the best and maybe only way to remedy this problem was to utilize a good quality headphone extension cable.<P>Overall, the DT931’s comfort was above average except for the two quirks mentioned above. The heat build up in the ear cups may not pose as a problem in colder countries so your mileage may vary. The connecting cord on the other hand was quite a problem. The coiling may seem neat at first but it proves to be too impractical if you like to utilize the full length of your cable.<P>Tweaks and Possible Improvements/Modifications<P>Many people claim that this pair of headphones with certain systems can be overly bright. This may be true in some cases so many users have found ways to connect resistors to increase this headphones’ impedance. This rolls off the treble and creates an even more linear frequency response graph.<P>If you decide to try this modification make sure that it is wired correctly and your resistors have room to dissipate heat. As always poor quality resistors may result in signal degradation leading to poor performance. Find the details about the modification here. We have opted not to review any pair of headphones in this review with tweaks/modifications as it may pose as an unfair advantage to a particular pair of headphones.<P>