Surround Effect and Listening Impressions

Going into this review I was curious as to just how convincing the G933/G633 headphones' 7.1 channel surround sound effect was going to be, considering these are producing all channels in the mix from a single driver per ear cup.

With multiple headsets on the market featuring discrete drivers for the multi-channel mix, Logitech’s decision to opt for a standard stereo driver setup might seem odd for a flagship 7.1 product; but simulated surround is nothing new. Left/center/right positioning is simple to implement from stereo drivers, but is it really possible to convince a listener that a sound is coming from behind them?

The Surround Effect

The surround channels presented to me as I listened through some home theater demo material were surprisingly accurate. Here's what I heard:

  • Center channel: Both drivers are used at equal volume, and no effects seem to be employed. Depending on how you hear mono this will seem to be directly in front of you, or perhaps in the center of your head.
  • Front left and right: The “center” channel is used to create the illusion that the speakers are actually in front, and not just in the extreme left and right. Thus, left is actually left-center; right is right-center. The feeling of a front left/right speaker is realized quite effectively.
  • Surround: The left and right surround channels in the mix are simply the untouched L and R channels from what I could tell. With “front” L/R using the center channel to make the sound feel forward, the surround L/R sounds like it’s coming directly from your sides. Which, of course, it is.
  • Rear surround: As these are 7.1 headphones there must be a rear surround, and this back L/R effect is less effective. Unlike the front L/R effect it was harder for me to place where the sound was coming from, as the rear surround was just distinct enough for me to determine that it was different (it almost sounded like it was below my ears); but I never had the impression that the sound was behind me.
  • Subwoofer: In surround, the .1 (as in 5.1 or 7.1) is the discrete subwoofer channel, also known as LFE (low frequency effects). To that end the G933/G633 is still only working with a pair of 40 mm drivers, which are of course also charged with the reproduction of all other frequencies at the same time. How did the headsets do? Bass is certainly not exaggerated but still very good; extended, dynamic, and controlled. I would equate the sound to a very good pair of full-range loudspeakers, but they fell short of a dedicated sub (individual levels can be adjusted to taste).

Overall the surround effect was really good – and far better than I expected. I'd equate the experience to a really good sound bar. Nothing beats well set up discrete drivers in a home theater, but a sound bar can give you a nice front surround effect (and sometimes more). For a pair of stereo headphones to provide a convincing surround effect is very impressive, and a testament to the surround effects from Dolby and DTS. Even though I didn't find the “rear surround” for a 7.1 mix convincing, the 5.1 performance overshadowed this.

Dolby vs. DTS Headphone:X

To briefly compare the two available options, the effect using the Dolby setting was less spacious, but perhaps more directionally accurate. With DTS Headphone:X, I felt the effect was a more three-dimensional than the Dolby setting. DTS Headphone:X offers a pair of options to let users customize the simulated “width” of the sound field, but even at its default it was very wide, and actually made Dolby seem rather flat by comparison. However, when listening critically to material mixed in 5.1 and 7.1 Dolby TrueHD, the Dolby setting offered a surprisingly precise, directional surround.

In the end, for movies I preferred Dolby, and for gaming and all other content I preferred DTS Headphone:X, which was a little more exciting and spacious. This is all personal preference, of course.

Stereo Listening

Finally, I tried out Logitech's Pro-G drivers without any surround effects using some familiar source material. Both the G933 and G633 offer digital audio via USB (or wirelessly via 2.4 GHz with the G933), and also via a passive 3.5 mm audio input. Both headsets include the necessary 3.5 mm cable (which also contains an inline volume control and mic).

Before continuing I'll point out an interesting aspect of the design; the position of the 40 mm drivers, which are angled slightly in toward the ear.

A view from the front actually shows the angle a bit better:

Such an angle is used to great effect with the well-regarded Audio Technica AD700X, and helps to provide more realistic imaging (the positioning of the sounds within the virtual stereo stage) for those "audiophile" headphones. I was curious to see what effect it had with these headsets with 2-channel listening. To that end I began with both uncompressed (16-bit, 44.1 kHz) music from CD rips, and then on to compressed music via Amazon and YouTube. The sound from the internal DAC was admirable, with very good clarity and good dynamics.

Moving on to high-resolution music files required the use of the 3.5 mm input, which was fine with me as I needed to test this out anyway. It is unfortunate however that those seeking greater bit depth won't have a choice in the matter, as the internal DAC is unfortunately limited to 16-bit audio (with a sample rate of up to 96 kHz). This won't pose an issue to most users, but it's worth noting that a wired analog connection will be required for not only high-res music, but also to hear uncompressed 24-bit/48 kHz Blu-ray audio (Dolby TrueHD, DTS Master Audio) without downsampling.

Use of the 3.5 mm analog audio input means the digital-to-analog conversion and amplification is going to occur at the source (i.e. your sound card or portable device), so the quality will vary. For this review I used my Calyx M as a source, a high-end digital audio player (DAP) with a Class A headphone amplifier. I used high resolution 24-bit (88.2 kHz and 96 kHz), as well as native DSD files for my listening sessions.

The Calyx M DAP was used to test high-res music files

The word I thought of when attempting to describe the sound of the G933/G633 is "balanced". There was very little coloration to the sound; in this case, a slight rise in the midrange was all I could detect. Dynamic shifts where handled well, even complex passages were free of obvious congestion, and detail resolution was quite good. These didn't resolve the finest details from high-res music like a pair of 'audiophile' headphones in this price range can, but I found the slightly smooth presentation to lend itself well to modern music.

Overall, Logitech impressed me with their approach to the sound of these headphones. I would actually place these ahead of some dedicated stereo headphones I've owned for critical music listening, and they certainly offer a solid 2-channel experience that gets closer to the source than I would have expected from a "gaming" headphone.

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