The Sennheiser Experience (Momentum, HD650, HD600)

This is a “special” review, where I gather my thoughts about Sennheiser Momentum (over-ear), and at the same time I also talk about Sennheiser HD650, HD600 and their general phylosophy. I have been owning such headphones repeatedly for years, without ever writing a proper review for them.

I chose to buy the Sennheiser Momentum after becoming more and more intolerant to in-ear monitors. I wanted something with a similar signature to Westone UM3x, and I was only aware of poor quality portable closed headphones. Luckily, in the last 2 years or so, the closed can market has changed (and improved a lot), and after examining several frequency response graphs on Innerfidelity website, I decided to take the plunge and purchase the Momentum (Over-Ear).

The Momentum (over-ear version) is a closed headphone that shares a lot with well a amplified Sennheiser HD650, in regards to tonal balance and snappiness. The midrange is perfectly spot on, just as it happens with the HD580 / HD600 / HD650, and the other departments aren’t lacking. These Sennheiser models moderately relax the high frequencies, so the midrange jumps forward, and one can listen without having to focus on details.
The Momentum can’t deliver the same great amount of air the HD650 does, though, and the HD650 is much more capable of portraying large spaces and has certain qualities to the upper midrange and treble department, that confer voices, guitars and other instruments greater presence. The Momentum is a bit darker and lacks the same sense of “sparkling” realism, but its tone is still very believable, full and intensely colored. The Momentum can, at the same time, be relaxing, fulfilling, involving. When well amped, the Sennheiser HD650 also has more bass depth, power and resolution than its smaller sibling. Conversely, a poorly amped Sennheiser HD650 has poor recovery of the impulse, resulting in a loose sound, excessive midbass and untimely sense of pacing.
The snappiness exhibited by the Momentum – even out of a smartphone – isn’t present in poorly amped Sennheiser HD600 / HD650.

The Momentum (over-ear) is an impressive closed headphone. Sennheiser nailed the dampening, and understood that the driver needs to be big. It seems the right combination of things they already knew, after the closed headphones they had been making in the former years.
The Momentum (over-ear) have provide an impressive level of isolation, almost comparable to that of in-ear monitors, without the same discomfort. I can easily listen to music on the road or in subways, without ever overwhelmed by the noise. I can still hear it (especially in the latter case), but it doesn’t break the listening.
Just as a matter of additional information, Sennheiser put out also other two models, the On-Ear, whose frequency response looks pityful, and more recently the Momentum 2.0 (or M2), which I have listened to, for a few days. The Momentum 2.0 are quite good. They are similar to the Momentum, with a bit bigger cups, and more comfortable for some people. They sound a bit airier, acoustic guitars are more realistic, soundstage is bigger, but midrange is lacking in comparison, colder. I prefer the Momentum 1.0.

The Sennheiser HD650 is a side-step compared to the HD600. They both improve strongly in balanced mode (or push-pull), probably simply because power is delivered more easily. In single ended, even with a good amount of amplification, the bass can still be too loose, and the treble too recessed with the HD650, so that everything can sound too laid back compared to the HD600.
Some years ago, some audiophiles used to talk about single ended Sennheiser HD650 being “veiled” between 4-8 kHz (lower treble), perhaps because their systems weren’t powerful enough. Used in balanced mode (which is the way personally I could finally hear it well amplified), the HD650 has superior technical abilities to the 600 which push the former far ahead. The bass is no longer loose, everything is much faster and more detailed, and it doesn’t sound dark or overly laid-back.

The HD600 balanced has a very natural, balanced tonality, is fairly quick and detailed, and has absolutely remarkable impact. It really is a very hard-hitting, very dynamic and visceral headphone. Its imaging however is not the best, and the soundstage is a bit small. It’s not diffuse either, though – the imaging is definitely crisper and more defined that it is in a single-ended system.

The HD650 is a bit different. It doesn’t have as natural of a tonality, and is still much warmer and more colored. It also isn’t quite as hard-hitting, forward, or visceral, though it still is very impactful. It is, however, substantially more detailed and refined. It images better, though the soundstage isn’t the biggest either. It is a lot more transparent, and seems to get out of the way of the music better. Also, the HD650 has a very organic, liquid quality to its sound which the HD600 doesn’t have.

The Sennheiser headphone family gives me the possibility to mention an issue I have been thinking for a while: although there are several more capable headphones (especially in the electrostatic and orthodynamic domains), that have more extension in both bass and treble, a larger soundstage, better instrument separation, faster transients (and so on…), they don’t necessarily improve the listening experience, but often end up distracting the listener with something unnecessary, even overwhelming. One of the most representative examples involves listening to the Stax SR-007. It has such capabilities that time, the listener will feel like put in an acquarium, where the different sound layers are the equivalent of undersea creatures. When listening to experimental-psychedelic music from the ’70s, the overly dissecting capabilities of an Omega 2 can get too close to suggesting the LSD trips that might have inspired the musician, whereas headphones like the HD600 / HD650 (or several others – or speakers, even high-end one) convey the musical flow as a more compact message directed to the subject, without drowning him in the portrayal.