Imaging vs Soundstage
- Dec 3, 2022
- 9 min read
Updated: Dec 4, 2022
Case Study between Sennheiser HD660S vs Hifiman Sundara
Previously, I thought soundstage was everything for realistic and enjoyable experience. Now I have experienced Sennheiser HD660S, I feel now that imaging has a bigger effect on realism or immersive experience.
Definition
First off, let's discuss parameters and definitions that adds to the 3-dimensional mental image of sound. All three of these factors combine to make the virtual stage of the sound in our minds:
Imaging: Direction or angle of sound source. Although by most definitions, imaging does not include distance, I do want to add layering as part of imaging.
Instrument Separation: Sounds that occur at same time, can be heard as distinct instruments. Some define imaging and separation together.
Soundstage: Size or distance where the sound is coming from.
Most people will say imaging is only on the direction of sound, not the distance (which is more related to soundstage). I would agree before I heard HD660S also. Soundstage is an easier concept. This is the macro scale of the sound. Do I feel like I'm listening to the music in concert hall, studio, vs a small room? That is clear.
But imaging can also include micro scale distance information. For instance, I hear guitar playing at my 2 o'clock 10 feet away. Then there is a handheld maraca sound that is coming from same direction as guitar, but it sounds further away at 12 feet. This is not soundstage. There can be multiple layers that enhances the imaging.
Some people include separation under Imaging in their definition. That is fine. There is no right or wrong here. It is just how we put mental map to the sound. Imaging and separation are definitely related. Having good separation adds to the imaging. And weak separation also reduces imaging effect. But I just want to keep these distinct, because HD660S and Sundara do have different effects in all these parameters: imaging (including layering), separation, and soundstage.
(Note that when I say Imaging here, this is for music only. This is how we perceive the sound and create a virtual stage. This is not absolute directionality accuracy required for fps gaming. Neither Sennheiser HD660S nor Hifiman Sundara are good for fps gaming.)
With the definition out of the way, let's talk about the 2 headphones used in this comparison. Hifiman Sundara is the one at the left. Sennheiser HD660S is in the middle. Ignore the Sennheiser HD560S. I use that for gaming and not used in this comparison.
Sennheiser HD660S
For Sennheiser HD660S, we might need an essay on history of Sennheiser headphones. Just kidding. But we do have to talk about HD600 and HD650.
Sennheiser introduced HD600 back in 1997. It is neutral and mid-focus headphones that is well known for great vocals and timbre. Then came HD650 in 2003. HD650 has slight modification to the tonality (mainly warmer). For past 20 to 25 years, these 2 headphones have been considered benchmark and best-in-class mid-priced headphones. Today, they are basically considered legendary in their sounds.
Massdrop (not called Drop) collaborated with Sennheiser to make Massdrop x Sennheiser HD6XX. HD6XX is sonically the same as HD650, but build is slightly different. HD6XX is basically a cheaper alternative/replacement of HD650.
However, there are some drawbacks in HD600 and HD650.
Soundstage: These have very intimate sound; enclosed or small soundstage.
Imaging is not very good. Often referred to as 3-blob imaging. There is center image at 12 o'clock, right image at 3 o'clock, and left image at 9 o'clock; everything in between is fuzzy.
"Sennheiser veil": I don't think anyone listening to these headphones by themselves will notice it. But when compared to other highly resolving headphones, the "veil" shows up. It is basically lack of detail and clarity, which is compounded by the warm, lush, and wet sound of these headphones, particularly the warmer HD650.
High impedance: Both headphones have 300 ohm impedance, which is not a good fit for portable music devices like phones. I'm not sure how valid this issue is, because these are open-back headphones that most people will use indoors. As with many mid-tier and up headphones, these do need good amplification to sound their best.
I actually demo'ed HD600 or HD650 at electronics store in Japan 20 years ago. I don't remember which one I tried. One thing that stood out as a negative to me was the lack of soundstage. It was too intimate. At the time, I already have mid-focused Sony MDR-CD900ST (though not nearly as good as HD600/650), and I was looking for something with soundstage. Unfortunately, I went with v-shaped Audio Technica headphones. That was a huge mistake. V-shaped can sound exciting at first listen, but then there is no vocal connection. It took me years after that to realize my error and get back into music with more neutral headphones. But I digress...
In 2017, Sennheiser released HD660S. The Legend Continues. (That is Sennheiser's marketing slogan for HD660S). It supposed improved on the shortcomings of HD600/650:
Soundstage: Yes, improved. But still small in size.
Imaging: Yes, significant improvement. Not only address deficiency in HD600/650, HD660S is best-in-class and better than Sundara. More below.
"Sennheiser veil": Gone.
Impedance: 150 ohm.
However, HD660S only received average reviews. One of the biggest reasons is price and value. HD660S was released at $500 MSRP. Street price was initially $450-$500. Majority of the online reviews were done using that as price comparison to competition headphones. As result, HD660S received many average reviews.
There are also reviewers that enjoyed HD600/650 sound, and found HD660S to be unrefined. Obviously, everyone has their preferences. To me, HD660S sound is an improvement. And put it on par to compete (and beat) with Hifiman Sundara.
Currently, price should not be a factor. Sennheiser has dropped their prices recently. And the HD6x0 series of headphones competes well with the market.
Sennheiser | HD600 | HD650 | HD660S |
Amazon link | Check HD600 Price | Check HD650 Price | Check HD660S Price |
Price as of Dec 2022 | $278 | $315 | $299 |
Released | 1997 | 2003 | 2017 |
Impedance | 300 ohm | 300 ohm | 150 ohm |
Sensitivity | 97 dB | 103 dB | 104 dB |
Weight | 260 g | 260 g | 260 g |
Amazon link | Check HD600 Price | Check HD650 Price | Check HD660S Price |
Hifiman Sundara
Hifiman is Chinese companies that has focused on planar magnetic headphones. Recently, it has introduced many headphones that provide "audiophile"-level sounds at entry-level prices. And its mid-tier offering is also very solid, basically with Sundara. When Sundara prices dropped from $400 to $350 to $300 over last few years, many consider Sundara to be the best value king in this mid-fi market.
My first entry into mid-fi sound is with Hifiman Deva. I got it as refurbished for $180. Deva is quite unique in that it has a detachable bluetooth dongle. It can be purchased standard (with dongle that can be used in wireless bluetooth mode) or wired (without dongle). Since then Hifiman updated Deva to Deva Pro. There is minimal sonic changes. Main changes are color (brown to black) and cabling (single cable to left earcup on Deva, to split cable to left and right earcups on Deva Pro).
Hifiman sound in general can be characterized by neutral sound, details and clarity, imaging, instrument separation, and open soundstage. Of course each model at different price tier will have their own pros and cons.
Downsides of Hifiman Sundara and Deva headphones are:
Dry and analytical sound: Vocals and timbre are no match against Sennheiser HD600/650/660S.
Comfort: This is highly personal. Planar magnetic headphones tend to be heavier. And with that weight, headphones' earcups, pads, headband need to distribute that weight. Unfortunately, I find Deva and Sundara just passable in comfort.
Quality Control: There are reports online of higher than normal QC issues with Hifiman headphones. My take is that QC issues seem to be real. These are defects (channel imbalance, dead driver, buzzing, creaking, etc) that should have been caught at the factory before they are shipped to customer. However, it is very hard to assess the severity (or probability) of the issue based on online forums. Chances of getting a bad unit is still likely low, but something consumer should be aware of.
Difficult to drive: Although planar magnetic headphones do not have high impedance, they tend to have have low to very low sensitivity. This is confusing and difficult situation for entry-level market segment. New audiophiles spend $100-$150 on Hifiman headphones, then realize they need to almost double their budget and spend another $100 to buy an amp.
Hifiman | Sundara | Deva Pro | Deva Pro (Wired) |
Amazon link | |||
Price as of Dec 2022 | $299 | $289 | $159 |
Released | 2017 (original) 2020 (revision) | 2020 (Deva) 2021 (Deva Pro) | 2020 (Deva) 2021 (Deva Pro) |
Impedance | 37 ohm | 18 ohm | 18 ohm |
Sensitivity | 94 dB | 94 dB | 94 dB |
Weight | 372 g | 360 g | 360 g |
Amazon link |
What Makes Realistic or Immersive Sound?
Many people use the term soundstage to talk about realistic or immersive sound. Is soundstage the biggest factor? It is definitely a factor, but I don't think it is that deciding factor.
Having a soundstage vs not having one is super important. Once soundstage is present, is larger soundstage better? Larger soundstage can actually be detrimental. It can make a studio recording sound like it is in a concert hall. It will cause vocals and instruments to sound recessed and too far away.
In terms of soundstage comparison between HD660S and Sundara, Sundara has clearly larger soundstage than HD660S. On HD660S, I feel I'm on the stage with the band. Vocals are very forward, maybe only 5 feet away. And instruments are off to the sides 5-20 feet away. On Sundara, everything is scaled up. I feel like I'm listening to the band in 1st row in the audience. Vocals are further away, maybe 10-15 feet away. And instruments are even further away.
Both have soundstage, just different scale. Soundstage here is not a deciding factor on realism. It just depends on your preference and expectation.
Sennheiser HD660S: Layering
With the smaller soundstage, HD660S actually produces more imaging information and instrument separation. The difference is layering. Some instruments sound closer, while others sound slightly further away. This layering just really enhances imaging and separation; bringing music to life.
Plus, the vocal presence is very forward on HD660S. This just provides a bigger contrast on vocals vs instruments. So even with a smaller soundstage, HD660S sounds more realistic and lifelike.
Hifiman Sundara: Soundstage and Instrument Separation
As mentioned, Sundara has larger soundstage. That is probably the only clear advantage that Sundara has over HD660S. Sundara is not bad in the other attributes, but just does not differentiate from HD660S.
Sundara has good imaging and separation. Instruments are clearly separated in direction. Even in the busiest tracks (where many sounds are playing on top of each other), Sundara's planar magnetic driver is very fast and can play each tune distinctly. In very extreme cases, where there is just jumbled mess of sound, Sundara actually outperforms HD660S. An example is The Holy Men by World Saxophone Quartet. I can close my eyes, can imagine and identify each sax instrument easier on Sundara.
In general listening, Sundara feels 2-dimensional with instruments. It is like a wall of instruments. I can only hear direction/angle, but no variation in distances of the instruments.
The 3-dimensional feel only comes after combining vocals and instruments. But even the vocals vs instrument layering is not as drastic as HD660S, likely due to less forward vocals on Sundara.
Conclusion
What is more important to immersive experience? Often people only mention soundstage. For sure, having soundstage vs no soundstage is the first step. Once soundstage exists, larger and more expansive soundstage does not mean more realism. Imaging (particularly layered imaging) adds the 3-dimensional immersive experience, even with a smaller soundstage. So in terms of realism and immersive experience, HD660S wins over Sundara. In case those of you care about how HD660S and Sundara compares in other factors, I will compare them below:
Tonality
Sundara is more neutral. It has more balanced bass/mids/trebles. HD660S is more mid-focused. HD660S sounds warmer in overall tonality in comparison to Sundara.
Bass: HD660S bass is more prominent. It is more voluminous and has more body to the bass.
Mids: HD660S dominates as it is mid-focused.
Trebles, Sundara wins, as HD660S trebles slightly recessed and lacking. As is, HD660S has less detail in the trebles. Something that can be fixed with EQ.
Vocals & Timbre
Sennheiser HD6x0-series is the benchmark for vocals and timbre. And HD660S is no exception. Since HD660S is mid-focused, it is not surprising it has great vocals. They sound warm, full, thick, and lush. And that goes with instrument timbre also.
In comparison, Sundara has dry and analytical sound signature. Vocals on Sundara will sound more recessed. If I just listen to Sundara by itself, I would say it is balanced. But once in comparison to HD660S, Sundara's vocals are recess.
Clarity & Detail
This is a draw, except for trebles where Sundara wins, because HD660S is recess in the trebles. It is not a big difference. It is something I wouldn't notice except in most critical listening. Once I EQ HD660S, trebles just open up and they are comparable.
Energy & Fun Factor
I listen mainly to alternative and pop music. There really isn't much bass in these genres. The energy comes from drums and kick drums. HD660S is a warmer headphone, there is more impact in bass and low mids. So there is HD660S has more energy and more fun to listen too. Sundara just sounds analytic in comparison.
Current Gear
I bought Sennheiser HD660S when the prices dropped in fall 2022. I was thinking I can use it for vocals. I wasn't expecting it be an all-around headphones. I was really surprised how well it performed technically, and how it actually outperformed Sundara. It kind of throws out my incorrect assumption that planar magnetic has better technical performance.
My new default headphones for music is now Sennheiser HD660S. And my go-to headphones for gaming is still Sennheiser HD560S.
I am getting rid of Sundara, because I still have Deva. Although Sundara is better than Deva, they are just a bit too similar and redundant. I have 5 headphones, 4 IEMs, 3 TWS. Too much gear. I believe (and hope) HD660S is enough to satisfy my audio gear needs for a long while.
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