Hifiman Sundara Open-Back Planar Magnetic Headphones - Official Thread

See I have a different hunch…that in fact the Sundara, HE4XX, HE400i and Deva all use the same (or at least very similar) drivers, and it’s the pads that are the main differentiator between them. Just take a look at Oratory1990’s measurements of them all below.

Sundara (likely original pads): https://www.dropbox.com/sh/654wxtmhlq0dhqa/AAD75QfJfKih_8QL-a1O9bESa/Hifiman%20Sundara.pdf

HE4XX: https://www.dropbox.com/sh/654wxtmhlq0dhqa/AAAB2SVYvAYTKwn44x3tcqZBa/Hifiman%20HE4XX.pdf

HE400i: https://www.dropbox.com/sh/654wxtmhlq0dhqa/AAD2c-oE5YmNovJZLa_foGLZa/Hifiman%20HE400i%20(preliminary).pdf

Deva (wired): https://www.dropbox.com/sh/654wxtmhlq0dhqa/AADPEKwIqSbIZcPdKwgHMiV1a/Hifiman%20Deva%20(wired).pdf

They all show dips and peaks in the same or very similar places, just in various amounts, and with different amounts of bass roll-off, both of which could be mostly explained by pad differences (pad seal being a major factor for bass extension of course). As you and Oratory now use the same GRAS 43AG measuring rig, I overlaid your measurement of the Sundara with the new revised pads (thin green line), with his measurement of the Deva (wired, orange line):

These are very similar frequency responses. And I don’t think it’s a coincidence that it looks like the new Sundara pads and the Deva pads are the most similar of all the HifiMan pads, both having the ‘bulge’ you were talking about (the pleather wrapping further around the edge to the ear-facing pad surface), and using the same materials. The only difference being the Deva pad’s slightly oval shaped inner ring that is not perforated like the Sundara’s, which could explain the minimal differences seen in the frequency responses above.

Now all this could easily be confirmed or denied, if either you, Oratory or someone else with a GRAS 43AG has several of these different models, swaps the pads between them and re-measures. Apart from your Sundaras (with revised pads), do you have any other HifiMan headphones on hand?

1 Like

I just reviewed the 400i (2020) and the Deva and they definitely weren’t the same drivers.

3 Likes

Okay this isn’t true. HiFiMAN generally aims for a similar tuning, so if all you’re looking to compare is FR then you’ll see a similarity between their lowest end models and their highest end models. This by no means indicates they’re using the same drivers. You can even tell just by looking at the differences in impedance and sensitivity.

Sundara:

  • Impedance: 37 Ohms
  • Sensitivity: 94 dB

Deva:

  • Impedance: 18 ohms
  • Sensitivity: 93.5 dB

Moreover, they aren’t all using single-sided magnetic arrays. In fact, the Deva’s driver surprisingly uses a double-sided magnetic array (unlike the Sundara), so these are very different transducers, even if they share similarities in overall tuning. I spoke with Fang Bian about this as well, and he mentioned that while we in the digital media space key in on certain parameters, like whether or not the magnetic array is single or double sided, there are a lot more parameters that go into transducer design - like diaphragm thickness, magnet strength, adhesive material and so on. These other parameters are likely also why the Deva simply doesn’t perform as well as the Sundara, in spite of the fact that it’s using a double-sided array while the Sundara does not.

This means that you can’t expect to throw Sundara pads on a Deva and have it sound like a Sundara, even if the FR is similar. You also can’t expect an HE-400i to sound like a Sundara just by throwing Sundara pads on it.

This also kind of goes into the whole question of what else is contained in FR beyond simply tonal balance, and while I do agree that many of the things we call ‘technicalities’ are captured by FR, this is also likely to be much more fine-grained information than you see in the graph overlay you’ve provided.

9 Likes

Ok read ‘very similar drivers’ as ‘very similarly tuned drivers’ in my previous post. What I was getting at is I suspect the main difference between these headphones is due to the pads, especially considering the significant difference in FR you heard and measured from the Sundara with the original and revised pads. I think it would be interesting and fun to test this theory by swapping pads between them and re-measuring if you have several of the models on hand :slight_smile: In fact, due to the similar design between the Sundara and (old) HE400i, and between the Deva and (new) HE400i, you could even do an informal blind test with them as well.

A quote from Hifiman’s founder - “Everything matters.”.

If you take two identical headphones but use different glue to assemble them they will sound different.

I don’t think there’s too much information you can draw from changing pads around.

It has been a while since I listened to the Sundara and have never heard the original HE400i, so I can’t comment there.

However, between the Deva and the new HE400i, pad changes will not get close to eliminating the differences between them.

You can read my comparison here:

How do you know a pad swap won’t make a big difference unless you try? :slight_smile: @Resolve has shown with his measurements that a pad change on the Sundaras significantly changed their sound, and Oratory1990 has measurements of several headphones showing sometimes drastic changes between pads.

The pads do influence the tuning yes, but I don’t think it’s quite as simple as just swapping pads - especially across models. I have a Deva here so i’ll give that a shot if I can (this could be interesting on its own). But importantly, as it relates to the Sundara, the only way to tell would be to have an old Sundara in and then pad swap to see if it is indeed just the pads. But this I can’t confirm since I don’t have an old revision.

2 Likes

Thanks that would be great, I’d be very interested to see those results. Yes to confirm the effect of the revised Sundara pads a swap with the old ones would be ideal. Maybe Oratory has access to both, seeing as his job is pretty much to measure headphones.

I literally said “everything matters”. Of course swapping pads will change things.

My point was you can’t draw conclusions about internal construction and how that relates to the entire line by doing some pad swaps.

I’m not saying it won’t make a difference to FR, it almost certainly will (whether they will be similar or completely different I do not know) but it will not improve the parts were the driver doesn’t perform as well on the HE400i as on the Deva (speed, detail etc.)

I’m curious. Why do you think it is likely oratory1990 measured the original pads? The measurement is dated Dec 2019.

Because his measurements differ significantly from @Resolve’s below (raw uncompensated, using the same GRAS 43AG rig), which we know were with the new revised pads.

And they differ in the ‘right’ way too. Although not as accurate, Resolve’s original measurements using his old rig (compensated) showed the Sundaras with the original pads having more pronounced dips at 1-3kHz and 6kHz and a peak at 3-5kHz, relative to his measurements of the new unit with the revised pads, see below.

Original:

New:

These more pronounced dips and peaks with the original pads are just what you see in Oratory1990’s measurements compared to Resolve’s of the new Sundara with revised pads using the same measuring equipment as Oratory (first graph in this post), strongly suggesting Oratory’s measurements were using the original pads. Oh and the dates on his graphs don’t really tell you anything - that’s just when he measured them, and since he mostly just measures headphones people already own and send in to him, they’re not necessarily recent purchases.

Again, we don’t know when the pad structure changes happened, and we don’t know if that’s solely responsible for the changes to the tuning. If anything, the differences here just support the initial suspicion that some reviewers got old stock units - although I’d have to ask him where he got it from. Regardless, unless one of us has them both side by side, with both pads (and/or potentially the pads that are sold separately from HiFiMAN directly), we won’t know what’s responsible for it. It’s just speculation otherwise. I’ll keep an eye out for an older unit to see if that’s doable because I’d personally really love to do this comparison and get to the bottom of it.

But at the very least, if you follow the purchase advice noted above (i.e., buying from a reputable dealer with a return policy and not through used sources), you should feel confident you’re getting the better measuring headphone.

4 Likes

I just wanted to mention that the above red line HEQ compensation curve of the Sundara is exactly how I hear them, even though the Gras measurements are probably more accurate. It is just ever so slightly elevated from 4 kHz and above, along with a bit of forwardness around 11-12kHz. Compared to the Clear, the Sundara is definitely brighter, and surprisingly has more air and midrange detail to my ears. The Clear is still my favorite, but the Sundara actually competes in many areas, and I often prefer it with all my favorite classical/instrumental music.

3 Likes

So I asked Oratory1990 and it does seem like the Sundara he measured had the original pads. He also responded to my hunch (my emphasis):

What do you think about my hunch that the main differences in frequency response between the Sundara, HE4XX, HE400i and Deva are down to their pads, especially considering the very similar FR of the newer Sundara version with revised pads to the Deva, as I showed above, which use very similar pads?

Pads certainly affect the sound a lot more than people would often think. I’d go as far as to say they’re as important as the actual driver.

For anyone who doesn’t know Oratory1990, he’s a highly knowledgeable professional acoustic engineer who measures and helps design headphones for a living as part of the company he works for. So from his answer above I think there’s good reason to consider my hunch as plausible (or at least possible).

2 Likes

So this is something I completely agree with. I don’t think anyone has said anything to the contrary, merely that it’s not the only thing involved in the tuning. Moreover, pad tunings are often unique to a specific headphone. This means that while the pads make a huge contribution to the tuning of a headphone, you can’t just swap pads around to different headphones and expect it to sound like the original headphone.

By the way, yeah Oratory is a very helpful person in this community and he’s responsible for much of my knowledge base as well. Definitely someone to look up to and learn from!

2 Likes

And I completely agree too :slight_smile: Swapping pads around will not make different headphones sound exactly like the original. However, in some cases, such as within a generally similar ‘family’ of models that may have very similar driver base tunings, swapping pads may get you pretty close, that’s all I’m saying. My hunch is that the headphones I mentioned are one such close family, but of course that can only be confirmed or denied through measurements of pad swaps.

1 Like

Yeah definitely there’s a chance it could end up being primarily (if not solely) in the pads, but we don’t know until we test it. I need to get my hands on an old revision to do that because there’s also a chance the driver revision that happened a long time ago is responsible for the FR changes we see. I do think it’s more likely that it’s to do with the pads, but I’ve seen some counterexamples where it wasn’t clear. This could be down to other factors as well, like positioning on the rig or test environment - so the bottom line is that we can’t be sure yet. The other big question in my mind is what’s being sold for the standalone pads, whether it’s the new version or the old version.

2 Likes

I did speak to one person who says they got a replacement pair of pads and they were the same as the ones on their revised Sundaras, and I’ve actually ordered that pair of pads I posted photos of myself now (Hifiman call them ‘Pali Pads’), so I’ll see what they’re like in hand.

2 Likes