Heir Audio 3.Ai

Continued from the 4.Ai analysis, Heir Audio 3.Ai is also a generic version of their custom IEM, 3.Ai. Everything is identical except the bore termination, of course. Since their generics have same internal components as the customs do, users who are currently using custom IEMs from Heir Audio might find this analysis quite useful as well.

PRO: Hand-crafted; nice aesthetics. 

CON: If something is radically different, it can be a good thing sometimes IMO. But that is not the case with 3.Ai. The mid-frequency notch is more prominent that that of 4.Ai, killing the overall spectral balance, and making the user effectively hearing-impaired at 3 kHz to 4 kHz range; A huge crossover network design flaw on Heir Audio's end. Moreover, there are more issues that need to be addressed: inverted polarity, high distortion, narrow bandwidth, and slow sub-bass.

ON SECOND THOUGHT #1: Just like 4.ai, changing the insertion depth does not alter the sound of 4.Ai that much, even with 3~4mm distance. Of course, there is not much of high frequency to be altered to begin with.

ON SECOND THOUGHT #2: Adding an extra resistance to 3.Ai is definitely not recommended- it will even further skew the frequency response, worse than the case with 4.Ai. 

ON SECOND THOUGHT #3: Heir Audio sells an upgrade cable,Magnus 1, for $149. Since the manufacturer says it has more silver content, it should lower the overall impedance of the IEM, and increase the output SPL due to improved efficiency in electroacoustic transduction. Since 3.Ai is more efficient than 4.Ai, the resulting relative output difference is actually larger.

And just as expected, my random $25 furutech cable from Ebay performs better than Magnus 1.

Heir Audio 4.Ai

Yet again, with the help of my friend, Inks, Heir Audio 3.Ai and 4.Ai (generic versions) have been analyzed thoroughly. Initially I requested a review sample too to the manufacturer, but somehow my emails did not make it to their inbox. Hmm.

I don't know much about Heir Audio, but it is known at Head-Fi.org that they make fine custom IEMs. Since their generics have same internal components as the customs do, users who are currently using custom IEMs from Heir Audio might find this analysis quite useful as well.

PRO: Hand-crafted; nice aesthetics. Low-distortion. 4.Ai's impedance characteristic is quite linear.

CON: Inverted polarity. A mid frequency deep-null is present due to the crossover network design error. Even assuming the IEM's design goal was to achieve an user-tweakable electric linearity, just like with the case of JH Audio, a steep notch at 4 kHz is not something that can be easily restored with a conventional equalizer. On top of that, the frequency bandwidth is still too short.

ON SECOND THOUGHT #1: Changing the insertion depth does not alter the sound of 4.Ai that much, even with 3~4mm distance. Of course, there is not much of high frequency to be altered to begin with.

ON SECOND THOUGHT #2: Adding an extra resistance to 4.Ai is definitely not recommended- it will totally skew the frequency response to another level. The IEM gains little more SPL over 10 kHz frequency range, but the deep-null becomes much worse.













ON SECOND THOUGHT #3: Heir Audio sells an upgrade cable, Magnus 1, for $149. Since the manufacturer says it has more silver content, it should lower the overall impedance of the IEM, and increase the output SPL due to improved efficiency in electroacoustic transduction.

And the plots on the left shows Magnus 1 surely does what it is supposed to do, but my random $25 furutech cable from Ebay performs better than Magnus 1. How odd.

Ultimate Ears UE900 part3: In-depth analysis

Continued from part 2.

Introduction

Ultimate Ears UE900 set the definition of Logitech's new reference in IEM acoustics: Low distortion, wide bandwidth, and linear impedance characteristic. More importantly, there are never-seen-before technologies implemented as well.

1. A pinhole bore
2. Knowles TWFK damping
3. Logitech: The pioneer of triple-bore technology?


A pinhole bore

Perhaps the most intriguing part of UE900 lies in its unique dual-bore configuration, with the large bore dedicated to the tweeter (Knowles TWFK), and the small bore dedicated to the woofer(Possibly Knowles CI-22955? Possible candidates are Knowles DTEC variants or Sonion 3300/3700/3800, according to one of my blog readers, Tom). My initial assumption is that the pinhole bore has something to do with an acoustic constriction action, which is a widely used low pass filtering technique in audiology for taming the frequency range above 5 kHz; the thinner the bore, the less output in the high. Moreover, as long as the bores are separated, the technique may help further eliminate any type of phase interference issues which may arise when a high frequency transducer is connected to a low frequency transducer in parallel.

from Wikipedia

So I did some constriction action calculation with that in mind.

However, the calculation attempt fails to yield anything valid- the measurement just does not match the numbers at all. Rather than cutting the high frequency, the pinhole actually amplifies the low frequency. What's going on?

So upon close examination of the frontal nozzle cap of UE900, I figure those four transducers actually share the same acoustic chamber within the nozzle. Thus, the dual bores do not really act as bores, but more as an acoustic enclosure with two ports working as Helmholtz resonators. (I guess the phase offset correction has been implemented only physically, by shifting the distance of the transducer from the outlet) Since the larger bore only affects the high frequency range due to its size(wavelength), the working principle of the pinhole is more of a concern here.

With so many acoustic filterings along the sound transduction path, no wonder the polarity of UE900 is so skewed up! Still, this approach is the first of this type of IEMs, so I shall give some credit to Logitech.


Knowles TWFK damping

There have been some speculations of UE900's high frequency transducer unit being a Knowles TWFK within the community. Even the damper configuration is identical, though UE900 uses 2200-Ohm red dampers instead of brown ones. Regardless, since there is enough room for a damper to be inserted on the larger bore, here you go:

Even with a slightest acoustic impedance drop, UE900 will lose all the frequency response above 16 kHz, since it is amplified by the larger bore's high pass filter, just like any other TWFK equipped IEMs. Try not to clog this bore with your bodily fluid!


Logitech: The pioneer of triple-bore technology?

Now we all know the dual-bore configuration techniques that are implemented on Triple.Fi 10 Pro and UE900 come from US7263195 & US7317806, issued on August 2007. While going through a bunch of research materials, I stumbled upon a patent document, US8116502, issued on February 2012. This patent deals with Logitech's all-new triple-bore & multi-layered bore configuration, both for generic and custom IEMs.

And it literally means that all of the custom & generic IEM manufacturers will have to acquire a permission from Logitech in order to manufacture devices with such bore configurations. You may call Logitech monopolizing the industry, but I know many companies haven't got the license, and made products anyway. Hopefully this will effectively eliminate whole bunch of random IEM companies with no objective design philosophy in mind.


In conclusion

Ultimate Ears UE900 is a well-made, class-defining product. It is free from the effect of electric damping, low in harmonic distortion, and reaching up to 20 kHz. Ultimate Ears really got their homework done, thinking about how bad Triple.Fi 10 was in those criteria.

The only thing UE900 is missing is the diffuse field linearity, and..

If someone is interested in a neutral tonality from UE900, hook up a 100-ohm adapter, block the pinhole, and insert the IEM nice and deep. That will yield the flattest, and widest frequency response, on par with electrostatic headphones! Really? Try it for yourself!

Ultimate Ears UE900 part2: General analysis

Continued from part 1.

After having all those $99 black friday liquidations with Triple.Fi 10 Pro for three consecutive years, it was quite obvious Ultimate Ears, which is now part of Logitech, were coming up with a new generic type IEM. Triple.Fi 10 Pro was expensive, bulky, and not quite accurate in terms of human ear acoustics.

And finally, in 2012, Logitech introduced UE900. Are they any better than Triple.Fi 10 Pro?

PRO: The frequency response extends up to 20 kHz. Extremely low distortion for a balanced-armature driver equipped IEM. Even considering UE900's quad-driver configuration, the impedance characteristic is very linear. Newly-implemented MMCX connectors are very durable, effectively eliminating durability problems involving while removing a cable.

CON: As expected, no consideration in the diffuse-field reference. The polarity has been inverted.

ON SECOND THOUGHT #1: Unlike its predecessor, UE900 becomes much more linear in terms of the diffuse-field reference when the IEM is underdamped. Thanks to the nice crossover design work done by Logitech, an electric damping doesn't affect the IEM in harms way at all.

The higher the output impedance of the amplifier, the flatter UE900 will become. (To be more technically accurate, the output will follow the impedance characteristic)

ON SECOND THOUGHT #2: When it comes down to a shallow insertion, I should say Logitech did a fantastic job with handling the issue. Not only the basic tonality of UE900 is still retained, the bandwidth loss is quite minimal.

ON SECOND THOUGHT #3: While simply equipping a 2200-Ohm red damper at the bore dedicated to the high frequency range, the manufacturer implemented a special pinhole-sized hole at the low-mid frequency bore, something I have never seen before. This shall be discussed in the upcoming part 3, the in-depth analysis.

Ultimate Ears UE900 part1: Aesthetics

Introduction

Triple.Fi 10 Pro has remained as Ultimate Ears' flagship model since 2004 among generic types. 8 years later, in 2012, Ultimate Ears finally announce their all-new generic flagship, UE900. Just like one of their custom types, UE-11 Pro, UE900 is equipped with a quad-driver configuration, along with a MMCX connector implemented cable.

Packaging

And the rest

Continued to part2, the general analysis

Final Audio Design Heaven-S [UPDATED]

A Head-Fi user, James444, generously loaned this IEM for analysis along with 2 other Final Audio Design's Heaven series models, A and C. Thank you! The first runner up is S, and A & C will follow.

As far as I know, Final Audio Design believes music is all about dynamics, according to 高井 金盛 (Kanemori Takai) -san, the representative director at FAD. Their design philosophy revolve around that very idea, and that is most likely how they came up with the Balanced Air Movement(BAM) technology, which is claimed to prevent acoustic leakage, while optimizing the air flow inside of the housing.

Of course, I do not believe in any type of commercially-biased claims by the manufacturer, unless the technologies are proven to be real. As shown on the above, the balanced armature transducer has a rear-vent, which is used for bass boost and pressure control. That vent must be connected to the rear volume of the housing and to the outside through slits. This is a simple venting technique promoted by many transducer manufacturers, and it seems FAD followed application notes quite well. Yes, BAM is real.

PRO: If something is radically funky, is it a good thing?

CON: The distortion figure, which is present on all three Heaven models, is so bad, the IEM is rather cult-like.

ON SECOND THOUGHT #1: These Heaven series models, including S, are truly unique, defying the common standard of electroacoustic engineering. A slightly bass-oriented tonality is understandable, but the distortion figure is far beyond human's perceptual threshold, which is 1% for music programs. The distortion becomes more audible as the volume knob turns up, and the resulting sound quality becomes somewhat close to the original TRON's background music. This kind of square wave-like modulation is never preferred for a hi-fidelity audio reproduction, but can be a good thing at the same time, especially when you listen to 70-80's SF movie soundtracks, or today's Daft Punk. It seems FAD have its own market & fanbase, and I don't think I can just judge their quality based on the common standard; I think I am going to fall in a love & hate relationship with FAD from now on!

ON SECOND THOUGHT #2: FAD Heaven-S will become a lot more peaky, when shallow-inserted. The deeper the insertion depth for Heaven-S, the better balance yielded.

ON SECOND THOUGHT #3: An electric damping will make this IEM more peaky as well.

ON SECOND THOUGHT #4: How does FAD's BAM technology affect the sound quality of the IEM? With the rear vent blocked, the sound becomes slightly less bass-oriented, as expected. Since balaced armature drivers with a rear-venting configuration do not get affected by the over-pressurization in the ear canal, I believe it is a good idea to just seal the vent off completely. (If ported all the way to the front cavity, BA drivers lose a sub-bass response) And it is important to note that the opening at the strain relief is completely blocked- it is not an acoustic vent.

ON SECOND THOUGHT #5: Upon close comparison, it seems A, C, and S are basically identical in terms of electroacoustic design at least.

Final Audio Design Heaven-A

Currently discontinued, Heaven-A was Final Audio Design's entry model for their BAM transducer series. Unlike others, A is not metal-plated; thus more light-weighted.

PRO: Click here for detail

CON: Left and right channels are not matched to each other, and the high frequency is quite limited compared to other BAM driver models.

ON SECOND THOUGHT: Although Heaven-A comes with BAMs, the sound quality is not up to the other BAM-series. The reason why? The manufacturer, FAD, shipped Heaven-A with different sleeves than C or S, which yield slightly less performance under same condition. I personally do not find this game to be very pleasant.

Final Audio Design Heaven-C

Heaven-C is yet another IEM, equipped with a pair of proprietary BAM transducers, from Final Audio Design. Unlike its little brother, Heaven-A, it is still available from the manufacturer.

PRO: Click here for detail

CON: The distortion figure is close to 4% @ 1 kHz on the left channel.

ON SECOND THOUGHT: Other than the slight channel mismatch and little more distortion, it seems Heaven-C is more or less same as A and S, in terms of spectral balance.