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Monday, April 15, 2013

TDK BA200 [UPDATED]

[Updated on 04/15/2013: The impedance stabilizer has been analyzed.]

Disclaimer #1: This IEM is owned by Inks. Much thanx to my good friend.
Disclaimer #2: Unlike that of Sony MDR-F1 or MDR-MA900, the impedance stabilizer implemented on BA200 turns out to be something other than a simple voltage divider. Read on!


BA200 is TDK's top-of-the-line IEM equipped with dual balanced armature drivers. Developed by the acoustic research lab at Imation, it is claimed to be tuned to have a very smooth frequency response, which is closely emulating the tonality of a reference loudspeaker system.

And most importantly, the acoustic research lab currently uses a conventional artificial ear fixture, G.R.A.S. 45CA, which has a pair of occluded ear simulator installed within, thus the accuracy of their acoustic tuning is absolutely guaranteed.






PRO: Impressive linearity in the mid-high frequency range & naturally decaying sub-bass.

CON: The tweeter's polarity is inverted & the high frequency does not even exceed 18 kHz.

ON SECOND THOUGHT #1:  As expected, TDK BA200 is extremely prone to tonal alteration caused by change in insertion depth due to its high acoustic output impedance characteristic. The IEM must be inserted up to the reference plane, which is equivalent to that of Etymotic Research ER-4, in order to retain its signature linearity. This is not a good news for the users with small ear canals.

ON SECOND THOUGHT #2: Just like Westone 4, adding a serial resistance balances out the tonality nicely. However, since the peak at 10 kHz remains unchanged, it is recommended that the value of additional resistance should not exceed more than 33 Ω.

ON SECOND THOUGHT #3: What's great about TDK BA200 is that users can easily swap out the stock filter, which is 2200 Ω, and modify the tonality by a great degree. In addition, it is very important to note that the extra dust mesh has no acoustic damping effect at all.

ON SECOND THOUGHT #4: The sleeve choice for BA200 is extremely limited due to its acoustic output impedance. Any sleeves that alter the bore size & length should be avoided, otherwise the overall bandwidth decreases tremendously. Please refer to the comprehensive sleeve analysis for further information.

ON SECOND THOUGHT #5: While some may disagree, I can't help but to think that BA200 is a mid-range boosted Ultimate Ears Triple.Fi 10 Pro. Although BA200 is not an upgrade from TF10, this is certainly a good news for the users, who find TF10's mid frequency range little too veiled.

ON SECOND THOUGHT #6: Interestingly, TDK claims they have successfully developed a ground-breaking technology, which can stabilize the impedance characteristic of the IEM. Conventionally, it is done by equipping a simple voltage divider, and normalizing the source impedance to a stable value. Thus, the transducer can be driven under a stable condition, regardless of the source's impedance. Some examples are Sony's impedance compensator, which is implemented on MDR-F1 and MDR-MA900, and Ultimate Ears' airplane adapter. However, such technique does not take the amplifier's capability in consideration, as some amplifiers might introduce oscillation upon a reactive load.

That is why TDK comes up with a Boucherot cell, or a Zobel network, which is widely used for stabilizing the voicecoil inductance of a loudspeaker. In constrast to Sony's approach, which alters the output impedance of the amplifier, TDK's approach alters the impedance of the driver itself. According to their patent, US20130028437, the impedance stabilizer flattens out the overall impedance characteristic of the IEM.
By assuming the IEM's driver as a simple electrical circuit 62 with capacitance in the high frequency, the stabilizer 60, counters the simplified circuit's impedance characteristic. Since a Boucherot cell is normally used to negate inductance of a loudspeaker, TDK's approach is rather refreshing. Although the target can't be perfect, this approach shall definitely yield better linearity. Without the stabilizer, BA200 would've had a decremental high frequency response as the source impedance increases.

Unfortunately, the electroacoustic effect of the stabilizer can not be assessed, as there is nothing known about the TDK BA200's transducer unit. If anybody has opened up his/her BA200, please let me know what is inside!

44 comments:

  1. Hi. What would be your recommendation between TDK BA200 and Rock it R-50? I know that both have different properties but if you were to choose between these too what would be your call?
    They both have similar price that's the reason for asking. Thanks

    ReplyDelete
    Replies
    1. Check this out: http://i.imgur.com/vGLDBdo.png

      First of all, the tonal-modifiability of both IEMs are equally good. While BA200 has better mid-high linearity, R-50 extends further in the high. On top of that, R-50 does better job when inserted shallow.

      So I'd call Rockit R-50 a winner.

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    2. Thanks very much for your input!

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  2. I would say that IF you can insert BA200 properly with the right tip ER6-18C, it's better and very hard to beat.

    R50 is more accessible but is more prone to sibilance and bass is lacking.

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    1. inks what about the HF5 with a serial resistance? this also is within the same price level as the other two. it would be great if udauda could do an analysis on that one too!

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    2. HF5 has better treble as it's 10k region is more controlled than the BA200, but I find BA200's midrange more balanced [HF5 has too much 1-4k imo] and while the HF5 has virtually no subbass, the BA200 has pretty good bass quality. Getting the BA200 can be risky though imo, ER6i-18c tips were the only tips that tamed it's 10k region to me.

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    3. I think i will go for the BA200. Its the first time i am jumping to the BA wagon so i will take the risk. It's also because of the impedance stabiliser stuff that it has and it should work nicely with my smartphone / laptop as a source. I am not gonna use any amp. Inks thanks for your input too

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  3. I'd dispute your comments on HF5. Mids are rich and smooth, sub-bass is there if the recording has it.

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    1. I totally agree with you Mark, it's just HF-series needs a little more refinement in terms of tonal linearity.

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    2. udauda is it possible to do some testing with various sources (amp, no amp, laptop, smartphone, whatever) concerning the proprietary impedance stabiliser that these phones have? It's not that i don't believe it. Others at head-fi have mentioned that it works (i.e. ClieOS) but i have no clue how this is accomplished. I would like to see some tests on its performance.

      Thanks. I hope i am not giving you trouble with my requests!

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    3. @Mark
      The HF5 is smooth but the 1-5k prominence [with impedance] makes it sound a bit too closed in/honky IMO. Without the resistance, it's simply lacking treble and air.

      There's a blatant subbass roll-off and very little decay. I might of exaggerated as it sounds fine with some recordings, but it's simply lacking presence in the low regions. Well, at least it doen't have bloated bass, that's even more problematic...

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    4. I'd agree with lack of treble when inserted deeply. When inserted shallow it sounds similar to good headphones. It would be interesting to conduct a survey among HF users that experimented with series resistors on what their sweet spot iss. I would have contributed but I've since upgraded to ER4P.

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  4. udauda thanks. Your article is very informative! cheers :)

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  5. Hey Rin let me ask you something. Why these guys have measured things different than you? Who is correct?

    I was checking this review and it says

    The BA200 shows an unusual increase in THD in the midrange, but it’s to just 2.5% at 1.2 kHz—an impressive result for a 100 dBA measurement.

    http://www.soundandvisionmag.com/blog/2012/02/20/review-tdk-life-record-eb950-ba100-and-ba200-earphones?page=0,1


    Also they have unusual FR graph for these in contrast to yours. Did they do something wrong? Just trying to make sense of things. If the objective analysis is still subjective to people then there is no hope :P

    ReplyDelete
    Replies
    1. S&V use a cheaper 2cc coupler, which is just a simple tube with a microphone attached at one end. Innerfidelity, Goldenears, and I use the occluded ear simulator, which reflects the eardrum & middle-ear impedance. I won't say the result measured with a 2cc coupler is technically wrong, but when you assess S&V's data, make sure to take them with a grain of salt.

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    2. Ok that would make sense as to why golden ears, inner fidelity and you look similar. I had to ask. Thanks!

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  6. Hello Rin, are there any negative side effects that the high frequency does not even exceed 18 kHz causes? In other words, is it actually audible?

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    1. If you can hear past 18Hz then it is audible. I did a test with tones and i could hear it past 18Hz. So doesnt make any difference for me. Check it for yourself.

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    2. While my right ear can easily hear over 19 kHz, my left ear didn't turn out to be that lucky, ~17 kHz.

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  7. Rin i just realised that there are two versions of this earphone. One with the cord in two parts and one with a whole. Which version did you actually test? Guys from head-fi are saying that the new version (1.2 meters cable) has been tuned better than the previous version (stock cable+extension cord=1.2 meters)

    THANKS!

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    1. The one with the extension cord, although I truly doubt there's any change done by the manufacturer in terms of acoustic tuning.

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    2. About the acoustic tuning this is what TDK told them to be specific. I dont know if its bullshit or not.

      In any case if we say that the drivers and the tuning is the same would it make any difference at all if the cable splits into two piece or not to the sound signature?

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    3. Unless Mr.John Bruss of Imation, the head of the Acoustic Research Lab behind the development of BA200, told you that, I simply don't buy it :P

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    4. I hear you. What about the question about the two piece cable? thanks

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    5. The junction that interconnects the stock cable and the extension is where the impedance stabilizer is implemented. I think they moved it to the plug, but if they somehow got rid of it in order to save the production cost, shame of TDK..

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    6. no the impedance stabiliser is still there as you can see from the photo below


      http://cdn.head-fi.org/7/7a/7ae99048_BA200.jpeg


      i am just asking if it makes any difference being two part cable or one piece to the sound signature.

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    7. this is the old version with the two piece cable. they just removed the intermediary cable jacks

      http://www.totallydubbed.net/wp-content/uploads/2012/05/DSC03733.jpg


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    8. Ah, that's right. The extension cable shouldn't affect the sound quality at all.

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    9. Got a reply from their technical team. The only change is the long cable due to multiple failures of the extension cord. If there is any change in the sound would be by this although you stated previously that it wouldnt matter at all.


      thank again

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    10. I see, good to hear. Please let me know how it went!

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  8. Rin, How do the BA200 compare to the UE900? I'm thinking of getting the TDKs because they are cheaper, also would the MH1C tips be good for it?

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    1. BA200 vs UE900.. UE900 is clearly a winner in every aspects: A true 20 ~ 20 kHz bandwidth, low distortion, great tweakability, and an interchangeable cable. You have wider range of sleeves to choose than BA200 too.

      BTW I'll upload the comprehensive sleeve analysis with BA200 soon, so you might want to check that.

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    2. yea we want sleeve analysis for the BA200

      so far only the large comply fit great in my ear plus also being comfortable :(((((

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    3. Now i am getting better with the silicone tips! :D

      yeah!!!

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  9. Ok RIN this is it !!!

    I need an explanation as to why i can hear this


    http://www.youtube.com/watch?v=pmLqeA9pQFs


    although according to your FR graph i shouldnt
    But i can definitely hear it !

    Is it possible that there is something wrong with the measurement???


    i have asked other people at head-fi to tell me if they can hear what i hear

    ReplyDelete
    Replies
    1. No, there's nothing wrong with the data, and BA200 is not the kind of IEM that can output all the information in the audible frequency range from 20 Hz to 20 kHz.

      First of all, check your equipments' harmonic distortion, see if it introduces a harmonic distortion. Then screw Youtube's lossy codec and download a lossless sample here: https://soundcloud.com/rin-choi-1/19khz-sine-1dbfs (Make sure you DL it, as the steaming doesn't properly play the signal)

      BA200's effective frequency bandwidth is only up to 16 kHz relative to 1 kHz in a 10 dB tolerance, Period. Still you can definitely hear it, since it is just a simple sine wave at 19 kHz. At 19 kHz, BA200's output drops down to -35 dB relative to 1 kHz, which indicates the frequency range is not part of BA200's effective bandwidth considering its overall spectral balance. With complex musical components present, anything at 19 kHz is as good as inaudible with BA200.

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  10. Hello Rin,
    Good job, as always!
    I'm considering buying Westone Star Tips, Etymotic/Shure triples or even custom ear tips for my BA200.
    Could you tell us, when we can expect the TDK BA200's sleeve analysis ???

    Tkanks in advance!

    ReplyDelete
    Replies
    1. Sorry for keeping you waiting. Currently I have UERM vs modded TF10 going, so the BA200 sleeve analysis will come up after this week.

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    2. Yup, the clock's ticking, and I am almost done with the most urgent ones. Will get to these ASAP

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  11. I've opened my BA200 and realized there are 1723 AcuPass drivers sitting there. I can read 1723WT02 type, Sonion logo and 1127 mark. I don't know what does 1127 mean but 1723 probably stands for 1723 AcuPass drivers version 02, which is unavailable on Sonion website. Instead You've got new 1723WT03 drivers described.

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  12. BA200 vs UE900.. UE900 is clearly a winner in every aspects: A true 20 ~ 20 kHz bandwidth, low distortion, great tweakability, and an interchangeable cable. You have wider range of sleeves to choose than BA200 too. And Excellent blog, Congrats to the Web Master, nice colors and text.
    Thanks for sharing your knowledge. God bless you.

    Cherry Marmalade Recipe

    Geetings from Venezuela

    ReplyDelete