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Tuesday, June 25, 2013

Hidition New Tears 6: New vs Old

[A big thnx goes to my dear friends, rubin, who is the owner of the older NT6, and shwl, who gladly loaned me his newer NT6. I truly appreciate them for the contribution!]

Originally started as a distributor of hearing aid brands such as Phonak and Starkey, Hidition is currently the only custom IEM manufacturer in South Korea. Unlike other CIEM companies such as Earsonics and Heir Audio, who still bang their heads against a tree stump when it comes to electroacoustic evaluation, Hidition has a capability of analyzing their own products using an equalizer, a microphone, and a simple silicone tube. It is quite disappointing though, that one of my friends, nalsse, have helped them setup the measurement jig, but Hidition never give him a credit for the contribution.

New Tears 6 is one of Hidition's top-tier models, which goes for $1,200, featuring a triple bore technology. As the internal crossover of the IEM is said to be revised once, the current model and the older model will be compared/analyzed together side by side.

CSD: NT6 Ver. 1

CSD: NT6 Ver.2
By overall, the second version is definitely an improvement: The newer model is better in every single aspects of electroacoustics, including distortion, interchannel variance and tonal liearity. And of course, just like any other custom IEM manufacturers, Hidition have also failed to calculate the insertion depth accurately here, resulting with a second-wavelength resonance at 10 kHz.

Phase response: NT6 Ver.1

Phase response: NT6 Ver.2
As expected, the phase characteristics have been completely skewed on both IEMs, thanks to the conventional multi-bore technology, which involves with adjusting placement of drivers to compensate any phase shifts at given crossover frequencies(wavelength), flipping the overall phase response off even further as a consequence.


While the first version becomes more linear with extra serial resistance added, the second version ends up with attenuation in the treble. In other words, the lower the devices' output impedance, the flatter NT6 ver.2 becomes.


Each bore has a dedicated role in Hidition's triple-bore technology. 

The bore diameter is actually thinner than that of Knowles dampers, so in order to carry out a damper modification, the damping screen has to be extracted from the plug, and inserted individually into the bore.


shwl: Nordost 7N, OCC-7N silver-plated
rubin: Hidition old stock, Hidition new stock, 5N copper, DIYer(fate)'s flourescent cable, Nordost 7N
udauda(Rin): $20 Furutech cable from Ebay, Ultimate Ears stock

My friends have sent me seven cables for this analysis, and my two cables are added to the pot. As expected, the OCC-7N silver plated cable and the Ebay furutech have the highest conductance, while rubin's Nortost 7N performs worse than others, indicating my friend rubin has been completely scammed.

And the actual electrical conductivity of each cable goes like this:

OCC-7N > Furutech > UE stock > shwl's Nordost 7N > New Hidition stock > 5N > Old Hidition stock >  Fate's DIY flourescent cable > rubin's Nordost 7N


By utilizing both electrical and acoustical damping modification techniques, NT6 can be finely tuned to match the Olive-Welti reference target. As far as NT6 ver.1 goes, insert a gray damper into the tweeter bore, and equip a 33 ohm resistor. On the other hand, as NT6 ver.2 is pretty much on target, a white damper on the tweeter bore will do the trick.


The difference between ver.1 and ver.2 is quite huge. Not only the crossover design has been revised, the overall acoustic damping scheme has been adjusted to tame the harshness of ver.1.


  1. Great review as always!

    Glad to see your first custom IEMs review. Do you have any plan to review other custom IEMs? I asked so because there was an item on your "upcoming" list.

    Quite a while ago you mentioned in one of our PM conversations that custom IEMs offer no advantages above universal IEMs, but in a recent post you mentioned that custom fit can improve SQ(?) acoustically. So I am most curious of your current thoughts.


    1. How are you, Rick! Aha, the plan's changed as the contributor sent the CIEM back for refit. Review's still scheduled though, just need more time. :P

      My argument still stands, as it is virtually impossible for a CEIM company to accurately calculate the optimum depth at which the user's reference plane is located- Damper location adjustment only complicates the matter by shifting the bore resonance, not to mention the second bend analogy is only an extremely vague approximation.

      Unless a CIEM manufacturer correctly address the issue, such as by measuring every user's ear canal resonance or via CT scanning, given their internal designs are equal, a CIEM can't possibly compete against an universal in terms of tonal linearity & high frequency extension.

      Then what about all the reviews blatantly glorifying the custom in-ear technology? I'd say they are all good SF-horror reads, but I'd rather recommend "at the mountain of madness" by H. P. Lovecraft. You can't go wrong with Cthulhu Mythos!

    2. Surely the insertion depth of UIEMs is even more unpredictable? ?.?

    3. Problem solving with an UIEM can be as simple as looking for a peak by listening to a sine sweep, given that the resonant property of the IEM/sleeve is known. And just avoid the peak by adjusting the insertion depth according to the finding.

      But with a CIEM.. you've just hit a dead end.

    4. ... you make it sound like our ear canals are a straight tube you could push the UIEMs in like a plunger... and that there are markings in that tube that allow you to sit them at the same depth every time o.O

    5. As long as the insertion depth can be secured past the cartilage portion of an ear canal, yes it is as simple as that.

    6. If using CIEMs, I suppose a similar hearing test can be conducted and the CIEMs sent back to the manufacturer for a remold with the same shape (for same resonance properties) but internals rearranged to tame the resonance? This is of course assuming a hypothetical CIEM manufacturer who would be partial to such remakes.

    7. That sounds like a feasible solution, but after four remolding, which is equivalent to more than 6 months of effort, ACS UK still didn't get a clue what the problem was LOL

  2. IMO both universal and custom are the same when it comes to insertion depth issues. It's just that for universal consumers can flexibly change the depth to match manufacturers' intended designs. While in custom's case if the technician screws up there's no way you can fix it.