The Sennheiser HD 598 Cs are the closed-back variation of the popular HD 598. They deliver a good sound quality with a few improvements thanks to the closed-back design but also some drawbacks for more critical listeners. On the upside, they're slightly more versatile because they isolate better than the open back model but not enough for commuting or traveling.
The Sennheiser HD 598 Cs keep the same aesthetic as the open HD 598. The earcups are closed compared to the perforated back of the open model, but the build quality is the same, as well as the slight bulkiness of the design. You can skip, play and pause tracks with the added inline controls but you can't change the volume, which is slightly disappointing. Unfortunately, the different padding on the earcups feels a lot less comfortable than that of the regular HD 598, although it does isolate listeners a bit better.
The Sennheiser HD 598 CS look pretty much indistinguishable to the open HD 598, especially at a distance. However, upon closer inspection, you will notice the slight difference in the padding and the closed-back earcups that have a matte finish instead of the perforated metal back like the regular HD 598. They look pricier than their actual cost giving them a somewhat high-end appeal. They only come in the understated black color scheme, which shouldn't be an issue for most listeners but they won't stand out in a crowd.
The Sennheiser 598 Cs are decently comfortable headphones, but they're not as well padded as the open 598 variations. The padding used for the ear cups on this model is a bit stiffer, which makes the headphones feel tighter on the head. This results in a fit that's a bit more tiring to wear for extended periods of time unlike the open 598.
The 598 Cs, unlike the open variation, have a cable with an inline remote that provides basic call/music and track skipping functionality. Unfortunately, the button is not very responsive, and the lack of volume controls is a bit disappointing.
Like the Beyerdynamic DT 770, the HD 598 Cs are bulky, and the earcups do not fold or lay flat to take less space. They're not particularly portable headphones, and they're not designed to be. And although they're not as big as some of the higher-end models of the same series, they're still too cumbersome to carry on your person without a bag. They also don't come with a case or pouch, which is slightly disappointing.
The build quality for the Sennheiser HD 598 Cs is above average but slightly weak at the joints. The headband is reinforced with a metal frame, and they feel sturdy enough to withstand a fair amount of physical stress. Unfortunately, the swivel hinges are a little thin and seem like the most likely area where they may get damaged.
These headphones are stable enough under normal, casual listening conditions but they're not intended for and won't be ideal to use while running. They're a bit bulky and sway a lot under strenuous activity. On the upside, the cable will detach if hooked on something provided you do not lock them into the earcup.
The Sennheiser HD 598 Cs are a good-sounding pair of closed-back headphones. They have a well-balanced Bass reproduction, but those with glasses or long hair may experience less Bass under certain conditions. The mid-range and treble range are also well-produced, but vocals and leads may sound a little forward. On the other hand, they don't have an as open and immersive Soundstage as the open-back variation.
Excellent Bass Range performance. The overall bass response is nearly flawless and within +/-1dB of our Target Response, if you can achieve a proper seal with these headphones. The plot shown here is the average of 25 measurements done on 5 human subjects. We noticed that subjects who have long hair or wear glasses with arms that aren't flush to their temple measured less bass.
Good Mid Range performance. Low-mid is very well reproduced, but mid and high-mid are consistently overemphasized by about 3dB. This tends to push vocals/leads to the front of the mix.
Decent Treble Range performance. The 5dB dip around 5KHz has a small negative effect on the detail and articulation of vocals/leads. Also, these headphones may sound slightly sibilant. (Sharp S and T sounds).
Poor Consistency. The lower regions of our over-ear and on-ear headphones are measured on 5 human subjects, 5 times each. We noticed that subjects with glasses or long hair didn't achieve a seal as good as other subjects, and therefore experienced a significant drop in bass. However, this wasn't apparent to them until we made the measurements. We noticed that glasses with arms that were not flush to the temple, had a bigger impact on the bass measurements.
Very good harmonic distortion performance. The amount distortion in the Bass Range is slightly elevated, but humans aren't very sensitive to low frequency distortion. The Mid and Treble ranges show very little distortion, regardless of level.
The Sennheiser HD 598 Cs naturally isolate more than the open 598 due to their closed-back design. They also leak a lot less. However, compared to some other closed-back headphones their isolation performance is below average. They will let in enough noise in loud environments to be distracting when listening to your music at average volumes. They also leak quite a bit, so the people around you may hear what you are listening to.
Poor isolation. These headphones don't isolate any sound below 300Hz. However, the closed-back earcups of the HD 598 Cs achieve an average amount of isolation in the Mid Range, by attenuating the sound by about 12dB. In the Treble Range they achieve about 32dB of isolation which is good.
Poor Leakage. These headphones leak sound over the relatively broad range of 400Hz-4KHz, which covers parts of Mid and Treble Ranges. However, the overall level of the leakage is not very loud.
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