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[IEM] Dynamic vs Balanced Armature Bass

Discussion in 'Sound Science' started by SilentNote, Jul 22, 2019.
  1. SilentNote
    So it seems like dynamic driver bass is generally preferred to balanced armature bass. This can be observed by hybrid IEMs generally using dynamic drivers for their low frequencies. While there are exceptions like Sony IER-Z1R where the low frequency is driven by BA transducer (and done very well); generally dynamic bass seem to have more impact and BA bass tend to be an unsatisfying tap.

    What causes this? Is it distortion? But from what I know even IEMs with low distortion can demonstrate this difference. Is it frequency response then? Why aren't BAs simply tuned to have similar frequency response to the dynamics then?

    Anyone able to shine some light to this matter is much appreciated.
  2. castleofargh Contributor
    my official answer is that I have no idea. my less official answer is that we probably can't trust people's impressions. and my own hypotheses consider a situation more complicated than it might first appear to be.

    anytime we consider BA vs DD, we're in fact implying many more differences. like how a dynamic driver is usually used in a vented configuration or with at the very least some significant internal space to give some freedom to the driver. a vented setup will obviously feel different compared to a sealed ear, from the physical sensation, the amount of isolation from ambient noises, to possible occlusion effect when we move walk etc. people dismiss that because they like to think that they can treat sound in some purely independent and way, but that's obviously BS.
    as for some internal space inside a sealed shell, some BA drivers also work like that, so maybe we'd need to try and have this conversation between already 4 distinct types of configurations. more if we start to count micro dynamic drivers as being different from their bigger brothers.
    then, be it DD or BA, some IEMs do have some pretty nasty distortions in some places atypical place, or in typical places but in excessive amounts. for that the listening levels may play a big roll, as the typical nominal output of a BA driver is often rather low. looking at the specs for the BA drivers used in a specific IEM(specs from Knowles or whoever) might help. or at least try to get some THD measurements around the concerned output levels. all the cases where bigger than usual distortions are found, should probably be removed from the samples of whatever test we envision. my measurement rig is honestly not right for that type of measurements, I have very little latitude between ambient noise in my room and the mic itself(not the right type of mic for that) distorting with high SPL sounds. so I can't test different output freely and use that as supporting evidence of anything.

    then the actual FR is almost always going to be significantly different. so basically we notice differences in sound(if I go with the assumption that people can at least do that correctly, which is not a given), and then we pretty much arbitrarily decide that something isn't caused by the FR difference so it must be due to the driver type. that's obviously not a serious approach to a diagnostic. most of our impressions/ideas about what we find different in such a situation would fall under "correlation does not imply causation". you could read that in the ER4 topic in the last few days. people very confident about their ideas that it's not FR, but most haven't ever done a listening test with different IEMs properly EQed to sound the same. in fact most wouldn't know how to do that in the first place, as it's a challenge. I can EQ my IEMs based on how they measure in my coupler, that's not very hard and if the difference is rather small, REW can help automatize that part. but then if those IEMs have different insertions, do I know that I'm placing them exactly the same way in my ears? a certain resonance measured in the coupler, will most certainly end up at another frequency in my ear(if I even can get both ears with the same). so doing some crap like EQing based on some online graph, and still hearing a difference, that's evidence of absolutely nothing. even if we had the exact same response for both IEMs, if the listener can feel a different from the fit or weight, that's a bias, and it's expected to still trigger an overall impression that they are and probably sound different. so when someone confidently claims to know that what he's hearing isn't related to FR differences, I'm really intrigued by that where that confidence is coming from?

    stuff with DD often sound a certain way to me. I completely understand why people would make that correlation between sound and driver type. I do. but DD often have a low freq roll off, and a bump somewhere in the low end and are vented. BAs often sound a certain way to me, but they often suck in the treble. many BA IEMs FR for a long time fell like a stone between around 10 and 13kHz. and certain very popular models of BA drivers had some really spiky crap near 10kHz. that specific model of Knowles BA has been so popular at one point that they might be the "BA sound" in the mind of many audiophiles for all I know. and at least the BA IEMs I purchase have high isolation(as that's my only reason to get them). I can say with certainty that listen to them at lower volumes than I do with my fully vented big fat DD IEMs in similar conditions. so if we rely on the equal loudness contour graph for humans, then sure enough they sound different and the bass are more ... everything with my DD and louder listening levels.

    also from a purely conceptual approach, if from time to time a BA driver does sound pretty much like a DD or vice versa(I certainly felt that on a few occasions), doesn't that invalidate the idea that the type of driver conditions a certain sound?

    I believe it's very important to be cautious and not jump to conclusion. when we don't know because the problem is too complex to solve for us, we should just say so. it's too complicated for me to be sure about an answer(if there is even just a single answer) ^_^.
    pstickne and SilentNote like this.
  3. pstickne
    BAs can be, and some are, tuned for bass. The BA bass drivers are very capable of reaching down low.

    My 10-BA K10Us seem to have as much low-end bass ‘sound’ as my “bass tuned” Hyla TE-5B. The difference is largely in the ‘feel’ of the bass. There is something nice with the subtle ‘whump’ and space it creates.

    BAs move relatively very little air - which is why they do not need an air port, and have slightly better isolation. DD bass is also generally a little ‘slower’, which can be a good thing. Maybe this helps with some of the ‘denseness’ it can create - outside of tuning.

    Preference is then a good bit on the listener and music they are listening to / mood they are in :p

    Also, the current MARKETING wave is for hybrid (including multi-DD) designs. Manufacturers are trying to sell new products, even if they aren’t strictly ‘upgrades’.
    Last edited: Jul 22, 2019
    baskingshark, SilentNote and buonassi like this.
  4. pstickne
    OT: I like the newer hybrid-treble BA designs - piezoelectric, e-stat, top-vented (TEAC, TIA), etc. - that have been coming out. I think there might even be some with designated DD tweeter for top-range. BA are definitely very versatile and compact drivers..
    Last edited: Jul 24, 2019
  5. pstickne
    Another example: JH Lola has DD for mids, and BA for low. It has tunable bass via cable pot.
  6. baskingshark
    Actually I like my music a lot and am also wondering about the different physics between a BA vs DD (I'm no engineer or expert). Would appreciate if any sound engineers or experts can give their advise.

    My current favourite IEM, the Audiosense T800, is actually a pure 8 BA driver IEM, but it features a vented subwoofer design. And this makes the bass on this IEM have very good subbass extension and oomph, and it almost sounds like a conventional DD bass. So as @pstickne and @castleofargh have mentioned, it is not so clear cut on how a BA or DD should sound in reality due to the different variabilities in design, individual hearing, eartips, physics etc.

    I own about 15 pairs of IEMs and I used to believe in general that the DD bass usually has more impact/subbass and displaces air better than a BA bass driver. The bass decay is also slower than a BA., whereas BA drivers tend to have better resolution and clarity in the mids. But nowadays, the BA drivers for bass are catching up to their DD counterparts and DD resolution/clarity are getting better so the line is getting blurrer.
    pstickne likes this.
  7. pstickne
    Some “bass tuned” all-BA IEMs (10-15+ DB gain on bass vs midrange; not necessarily dark). There are definitely others.

    - Final FI-BA-SS (1 BA, uses bass ports / chambers to “produce deep bass”)
    - Sony M9 (5 BA, one is a “super tweeter”)
    - Nobel K10/K10U (10 BA, 5x2)
    Last edited: Jul 25, 2019
    SilentNote and baskingshark like this.
  8. aminus
    I don’t know where this idea that the Z1R’s woofer is a BA came from but it’s 100% incorrect. Sony’s own site says the bass response is generated from the 12mm DD. A look at the design of the Z1R shows that the 12mm DD is low pass filtered in the magnesium housing. Please don’t spread misinformation.
    Last edited: Aug 13, 2019
    pstickne likes this.
  9. pstickne
    I missed such a claim above.. nice catch.

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