HiFiMan Deva (and the assumptions behind the HE5XX)

Discussion in 'Headphones' started by purr1n, Nov 1, 2020.

  1. purr1n

    purr1n Finding his inner redneck

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    The short story is that HE5XX was released, a few FR measurements were dropped, and then suddenly it seemed that almost everyone assumed that the HE5XX was a reskin of the Deva and got their panties in a twist. How dare Drop reskin a Deva and call it an HE5XX? How dare Drop invoke the name of the glorious HE-500 and use the Deva drivers! Surely Drop is deceiving us and we must call them out on this for their shamelessness!

    Will, Drop's product guy, attempted to explain that there actually was some effort to create a custom headphone with the HE5XX (of course from HFM's parts bin and bag of know-how), but his explanation satisfied no one. Of course not! Once everybody on the Internet has been wronged (whether rightly or wrongly), the pitchforks must come out. In times such as this, steadier minds must prevail.

    upload_2020-11-1_19-29-23.jpeg

    So let's proceed with various analyses. I don't know the total answer quite yet, I so will be doing this along with you.
     
    Last edited: Nov 1, 2020
  2. purr1n

    purr1n Finding his inner redneck

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    Here is the frequency response of the Deva right channel (red) compared to the averaged L and R responses of the HE-5XX. The Deva pads were used. The pads look the same other than the color and have the same dimensions. The stuffing on the Deva pads do feel slightly more resistant to squishing. The face of the Deva pads look like they are stuffed a more, even though external dimensions are the same. The stitching where the cloth face meets the pleather side are more flush with the face on the HE5XX pads. I will show photos of the Deva vs the HE5XX pads in a later post.

    The Flat Plate Coupler (no ear structure), which I will now fondly call scraps, because it really was made from scraps, was used because I get the most consistent and repeatable results from this. Also, the rig, because it doesn't have an artificial ear and on a flat surface, is much more resistant to minor placement and seal inconsistencies. Note that this rig has not changed since the V2 measurements in from Changstar, maybe 2012?

    Deva R Channel (RED) vs HE5XX (GRY)
    Deva using Deva pads
    Frequency Response
    Scraps Measurement Rig (aka FPC)
    upload_2020-11-1_19-37-30.png

    We can see that the HE5XX does measure in frequency response somewhat close to the Deva. The Deva's bass actually peaks and starts to roll off 20Hz higher than the HE5XX - there is some recovery toward 20Hz so it's not down so much relative to the HE5XX.

    The midrange "shark-fins", seen in some orthos, are in different spots. It's not uncommon even within a a single headphone for these shark-fins to be off slightly, but in this case, they are off significantly. The 8kHz peak is consistent between the two headphones. However, the Deva has a near 5kHz which does not exist on the HE5XX. The Deva also has a peak of higher amplitude in the top octave near 13kHz. I'm ignoring the stuff past 15kHz.

    Certainly there are similarities. It does seem possible that the Deva and 5XX could use the same driver and that the differences are a matter of manufacturing tolerances with the driver or the pads being slightly different.

    Let's continue to explore.
     
    Last edited: Nov 1, 2020
  3. purr1n

    purr1n Finding his inner redneck

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    Now let's do more of an apples-to-apples comparison using the same HE5XX pads on the Deva. Little by little, let's whittle away possible causes of differences. The Deva with the HE5XX pads is in Orange below.

    Deva R Channel (ORA) vs HE5XX (GRY)
    Deva using HE5XXpads
    Frequency Response
    Scraps Measurement Rig (aka FPC)
    upload_2020-11-1_19-52-6.png

    Whoa, what happened to the bass! It seemed to drop a lot more when Deva is using the same pads as the HE5XX. The 8kHz peak dropped a bit, but the 13kHz peak has jumped a bit. It's actually looking more like the HE5XX driver is not the same as the Deva driver.

    Maybe it's fair to say that the HE5XX driver is similar to the Deva driver, or based on the same tech. But so are all of HFM's headphones in the sub $500 range.
     
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  4. purr1n

    purr1n Finding his inner redneck

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    Photos of the Deva and HE5XX pads. The Deva pads have less squishy padding - at least it feels that way. The stitching on the Deva pads is more on the face on the pad, as opposed of the HE5XX pad where is is more or less on the edge of the face. Measurements above would seem to confirm that the pads are slightly different.

    pads.jpg
     
  5. purr1n

    purr1n Finding his inner redneck

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    Keeping the pads the same (5XX), let's take a look at distortion

    Deva (HE5XX pads) R channel
    Harmonic Distortions
    upload_2020-11-1_20-19-16.png

    That's actually very good and better than the HE5XX from 200Hz and above. The HE5XX produces more 2nd harmonic above 200Hz. Below 200Hz, it's similar, although it would appear the HE5XX may have a slight upper hand because of the lower 4th harmonic. HE5XX distortion results below for comparison:

    [​IMG]
    [​IMG]

    It's looking more and more that the HE5XX driver is not the same as the Deva driver.
     
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  6. purr1n

    purr1n Finding his inner redneck

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    Here are the CSDs. Both Deva and HE5XX exhibit low level continued vibration of the diaphragm. The peaks are different though. The Deva is a noticeable higher amplitude ridge (red color) at 13kHz. Otherwise Deva trades a small peak just past 5kHz for the HE5XX's 8kHz.

    HiFiMan Deva R Channel, HE5XX pads (for apples to apples driver comparison)
    FPC Deva R (5XX pads).jpg

    For reference, HE5XX CSDs below (see also: https://www.superbestaudiofriends.o...iew-and-measurements.10082/page-4#post-323472)
    [​IMG]
    [​IMG]
     
    Last edited: Nov 1, 2020
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  7. purr1n

    purr1n Finding his inner redneck

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    I think we have enough information here to determine that the HE5XX is not a reskin of the Deva. All things being equal (or even unequal), the HE5XX has better bass extension than the Deva. The distortion characteristics are different with the Deva performing better above 200Hz with the HE5XX having more second order; and the HE5XX performing marginally better bellow 200Hz with less fourth order distortion. The frequency response, verified with CSDs, show two additional peaks on the Deva, just above 5kHz and at 13kHz.

    Also, the pads don't appear to be the same either. I don't know if that counts, but I think it does count a little as yet another little difference.

    As for the headband, having a chance to try out the Deva headband, my preference is still for the HE5XX headband. The HE5XX headband is wider at the top. There is less padding on the HE5XX headphone, but the padding is more complaint. The extra width feels more comfortable on the top of my head. I am one of those guys with Klingon ridges at the top of my head, so skinnier headbands like the Deva place too much pressure on the ridge. I tried it on a while ago and it still hurts! Also, I should mention that the ratcheting mechanism on the HE5XX is a little bit easier to deal with. It's easier to actuate and move while staying in place. The Deva's ratchet mechanism binds slightly. It takes more force to move, and when it slips, I end up moving it several more notches than I wanted to. I felt I should mention this now that I've gotten my hands on a Deva. I wouldn't say that the Deva headband is better. Maybe it looks better, but the ergonomics aren't as good as the HE5XX.
     
    Last edited: Nov 1, 2020
  8. purr1n

    purr1n Finding his inner redneck

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    Lessons learned:
    1. Let's not be Internet Twitter hosebags and jump to conclusions. I mean, I too was probably thinking WTH when evidence was presented that the HE5XX and Deva had similar frequency responses (the fact is, a lot of HFM headphones have very similar frequency responses) - fortunately I got to my senses and put on my Spock hat.
    2. Let's give Drop the benefit of the doubt. There seems to be a love-hate them for Drop where people almost want to see them fail, yet love buying their products because they provide good value. Drop doesn't always knock it out of the park every time, but they do provide fantastic deals more often than not. Let's face it, we would be worse off without them.
    3. Frequency response alone is not the end-all be-all. There is way too much emphasis on this one single measurement and this measurement can vary too. Quality of seal can affect bass extension and placement inconsistencies can result in shifting of peaks and nulls in the mids and highs - there things tend to be very measurer dependent. Lets get more data before arriving to conclusions. In our Internet society where facts seem to be played with or even distorted, let's at least hold ourselves to a high standard.
     
  9. purr1n

    purr1n Finding his inner redneck

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    More data. Impedance.

    HiFiMan Deva Impedance
    YEL = Free Air
    GRN = On Head
    upload_2020-11-1_21-42-23.png

    Drop x HiFiMan HE5XX
    Impedance
    YEL = Free Air
    GRN = On Head
    [​IMG]

    Now this is interesting. Orthos are usually known to have a flat impedance. If this is what I think it is and principles of dynamic drivers apply (maybe somewhat), it could be that the small impedance bumps could represent Fs or something similar. In this case, the bump for the HE5XX is at a lower frequency. Could this be why The HE5XX has lower bass extension compared to the Deva?

    After all these years, we keep discovering stuff. I don't know if this will hold for other orthos, since these two headphones do seem to be underdamped.
     
    Last edited: Nov 1, 2020
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  10. purr1n

    purr1n Finding his inner redneck

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    Off the the top of my head and before I forget. We're seeing orthos that are of lower and lower impedance. The Verum between 8 and 12-ohms. And now this at 17 to 18-ohms. While I don't see an issue with anyone here, I think it's important to understand that we are getting close to speaker loads. These headphones are efficient, so I doubt there will ever be a problem. However I can see see cases were people want to run them at small desktop speaker volumes and crank up the bass 12db to Aphex Twin or FSOL. A sustained 30Hz bass drop running into 18-ohms at loud volume could light up your small iFi, Magni, Atom, etc. These amps were never designed with these loads in mind.
     
  11. Baten

    Baten Friend

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    Superb investigation. You definitely proved my personal conclusion ("likely to be the deva driver") wrong purr1n. Hats off.
     
  12. Vtory

    Vtory Illogical Spock

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    Excellent analysis. This would clarify the most critical confusion of those keeping eyes on he5xx.

    I am a little surprised Deva has nicer harmonics considering 5xx’s double-sided magnets. Comfort comparison also different than expected.

    Any comments on how devas sound subjectively?
     
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  13. Ardacer

    Ardacer Almost "Made"

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    Similar drivers in similar enclosures might measure in a similar fashion, might sound similar, who would have thunk.

    Distortion measurements are a dead giveaway it's not the same thing. I suppose the impedance peaks are indeed fs, as a result of the driver and enclosure differences.
    Perfect example of how looking at things from just a single point of view can be very misleading. This is similar, somewhat, not a mere reskin for sure.
     
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  14. Eric_C

    Eric_C Friend

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    Thanks Marv. I was definitely leaning towards the reskin conclusion myself, but what you've presented helps put that notion to rest.
     
  15. cameng318

    cameng318 Acquaintance

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    Thanks so much for taking time to make the comparison! There's more than enough data verifies Will's claims.

    They probably did tuned the magnets to have asymmetric strength, as asymmetry typically causes more 2nd order distortion. Deva is probably tuned closer to 50/50 ratio. I'm curious how they managed to have the same sensitivity, maybe they didn't opt for the strongest magnet for DEVA.

    Not only the Fs shifted down for HE5XX, but also the shark fins shifted down for the same ratio. After reinvestigating my T20RP after the T60RP thread, the shark fins are the resonance modes of the diaphragm. This suggests they either tuned down the tension or made the diaphragm thicker. I lean towards the former since Will implied it, but he also mentioned the coating, which might affect the thickness. However, the trace thickness to substrate thickness should still be the same, which I found to have the most impact on timbre.

    Now the choice is harder to make, BRZ or the GT86? DEVA is technically the better headphone with lower distortion (tighter diaphragm is technically better just because it's harder to manufacturer), but the HE5XX has better FR and may subjectively sounds more pleasant. Anyway, I'm gladed as a consumer to have choices at these performance to price.
     
  16. cameng318

    cameng318 Acquaintance

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    Also echo on the low impedance. It draws around 18 mA peak when drives at 90 dB SPL, which would push a lot of the small amps out of the class A region. 2 mA peak at 72 dB SPL would throw typically consumer electronics out of whack. Op amp usually sounds exponentially worse when drawing more than 1 mA. These headphones should at least be used with somewhat beefy amp.
     
    Last edited: Nov 2, 2020
  17. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Given both that HFM headphones often measure similarly and that planars in general seem more prone to unit-to-unit variations, though somewhat contradictory when considered together, I don't think there's enough evidence to argue one way or the other without more data points from additional pairs of the two headphones. (No, I don't think that's is worth pursuing.)

    I do recall that planars, especially HFM and Audeze, seemed to have more distortion variation among units of the same type. Was it Tyll that had data on that? I think we've tested some of that in the past too. Plus, there are plenty of stories about unicorn-grade planars.

    Or, hell, you could look at the HD650 when they recently changed factories. AFAIK, they used all the same parts. Only the assembly part changed. Doesn't even necessarily have to be any differences in the parts (supposedly) to get surprisingly different results. We all know Sennheiser is generally pretty consistent otherwise, so goes to show weird shit can happen.

    Maybe it's a reskinned DEVA. Maybe there are more significant tweaks. Maybe it's something entirely different.

    I still get the sense there's some marketing BS and Force hand waving at play here. But Drop's claim that this isn't just a reskinned DEVA seems plausible too.

    And while I'm still not convinced one way or the other, I'm not sure I really care enough about this. At worst, it's a misleading product, and at best still a product that obviously is not a resurrected HE-500 (not exactly hidden info to figure that out). These concerns are not anything I'd say carry much significance. It's a cheap planar that might capture some amorphous and vague spirit of what made the HE-500 what it was, and seems @purr1n thought it sounded decent for what it was without necessarily knowing, or at least mentioning, all...this.
     
  18. mk801

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    Didn't the HE-500 have a similar impedance bump at below 100 Hz (~85Hz)? More like a blip here due to the scale of the impedance-axis. Just presenting stuff that I remember encountering along the way well before this HE5XX business.

    [​IMG]
     
    Last edited: Nov 2, 2020
  19. rhythmdevils

    rhythmdevils Best SBAF member of all time

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    What’s the market for a cheap headphone that requires a “beefy” ie expensive amp to drive them? Kind of a strange place these phones have put themselves in.

    I guess the HD650 is the same but I doubt the he5xx scales much.
     
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  20. cameng318

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    Current constrained output stages like the ones from CMOY, O2, phone dongle, laptop, and cheap soundcards are likely to crap out even at normal listening levels.

    Output stages with quiescent current around 10 mA like the Vali Coaster might get loaded too much, that the distortion would be dominated by the out output stage instead of input stage.

    The both of the Magni should be good enough for normal listening levels. The relatively big surface mount transistors in 3+ and 8 parallel op amps in Heresey should be able to deliver 10 mA with ease. Though listening too loud may still got affected.
     
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