Etymotic Research ER-6: The TKer

Several weeks ago, I was able to grab a brand-new Etymotic Research ER-6 from m*xw**.com for $87. This is a discontinued item, and should have never been listed on the website. Well, I talked to the customer service, and they agreed to ship the very last item in the stock for me. Great service, indeed!

ER-6 was introduced in 2002, and it was to be an affordable version of ER-4S. According to Donald Wilson, the developer of ER-4 series:

"The new model will use completely different parts than the ER-4. The goal was to produce a device with a response close to the ER-4S with greater sensitivity, at about half the price. Because of price constraints the cable won't be removeable. Even if the response is close there is always the chance that it might not sound as good as the ER-4. I still plan to make a higher quality version of the ER-4 when I have more time." http://www.head-fi.org/t/3090/new-etymotic-headphone/30#post_38588

And in 2009, upon the launching of HF-series, the end of ER-6 was finally confirmed by an user at Head-Fi. It was a very sad moment for all of us, the headphiles, and Etymotic enthusiasts.

PRO: The frequency response target is quite on the spot. Etymotic Research claim ER-6's accuracy is 90%, and the data just verify that. Moreover, the impedance is quite high; It is almost free from the portable source impedance-induced damping error, which is a common problem for IEMs available in the market today.

CON: It is a pain in the butt(or fingers) to insert this headphone to the proper insertion depth, not because its form factor is large, but because it is too small & short. It is so small, when it is time to pull the headphone out, there is almost nothing to grab onto. I am not sure why the polarity of this headphone is inverted. Also, the distortion figure is slightly higher than the ER-4 series.

ON SECOND THOUGHT: ER-6 is a team-killer. While the current HF-series closely matches the response of ER-4P, ER-6 matches ER-4S, which is more accurate to the reference diffuse field target. No wonder they discontinued this piece of gem.

Just out of curiosity, I did a simple test with different silicone sleeves:

And ER6I-18C, bi-flange sleeves for ER-6i, yields the flattest diffuse-field response! (almost as flat as MC5 with ER38-18)


ON SECOND THOUGHT #2: I completely forgot to mention ER-6 is an OEM product of a Japanese manufacturer, Star Micronics Ltd's PH-001A. In Mead C. Killion's 2003 interview with Audiology Online:

AO/Beck: Can you tell me a little bit about the ER-4 and ER-6?
Killion: Sure. The frequency response of both is very similar to that of the ER-1 from ten years before. Both the ER-4 and ER-6 attenuate outside sounds and mimic the open-ear response so the experience is as close to live music as possible. The ER-4 provides somewhat higher isolation and a slightly more accurate frequency response. We recently found a partner in Japan that had a manufacturing facility in China, which resulted in the lower-cost ER-6 model. 

However, Star Micronics' current official website does not have any information on PH-001A. It does not even seem they are manufacturing balanced armatures anymore. Does anybody know what actually happened to them?

The effect of break-in: Sennheiser HD650

Introduction

It is generally known that a new pair of headphones must go through a "warming up(aka break-in)" phase for certain period of time before it opens up its true sonic potential.

According to AKG:

"...we cannot confirm that there is a burn in effect of the transducers taking place. Normally the sound of headphones changes only over many years and then mainly caused by the ear pads (less low end since the ear pads get more densely by sweat etc.).  However, during the first hours of use of headphones, the ear pads -  in the beginning a little stiff – start to accommodate to the users ears and head and the sealing becomes better, as a result the bass can be increased a little, on the other hand the distance between the headphones and the ear may become closer..."

from http://www.akg.com/forum/index.php/topic,1736.msg5270.html#msg5270

In contrast, here's what Grado has to say in regards to the headphone break-in:

"..As any mechanical device, the headphones will improve in performance with use.."

And according to Ultrasone, their recommended break-in period is about 100 hours:

Previously, both electroacoustic and psychoacoustic aspects of a 100 hours-long headphone break-in have been presented with SONY MDR-EX1000, a headphone with a 16mm dynamic transducer: The physical transformation is evident, yet its degree is not of a night and day difference, as audiophiles normally describe it.

Then how about with a larger transducer of a full-sized headphone, such as Sennheiser HD650?

Test methods

A brand-new Sennheiser HD650 is to be broken-in for 100 hours straight with XLO's break-in sample(100 dB SPL @ peak), driven with SONY NW-S639f with all of the tone controls turned off. Once the headphone is inserted in EURI's ear canals , its physical placement must remain untouched for the next 100 hours in order to prevent any placement-related deviations. Each 10 times averaged pre break-in & post break-in measurement data are to be compared, and should any type of change occur, they are to be reproduced back utilizing a binaural recording technique to be ABX-compared.

Test results

Impedance

The resonant frequency has been shifted, while the overall impedance lowered a little bit.

Frequency response

Time-domain characteristics

Spectrogram

Harmonic distortion

Subjective Assessment

ATTENTION: In order to accurately reproduce these binaural recordings, listeners must use a flat diffuse-field equalized headphone, such as Etymotic Research ER-4B and STAX Lambda PRO with ED-1. The accuracy of the reproduced result can not be guaranteed otherwise.

Reference sample

http://www.4shared.com/music/8X-Fjkrq/The_Lion_King_-_01_-_Charmen_T.html


A brand-new Sennheiser HD650

High quality sample:  http://www.4shared.com/music/C8QHxhIH/hd650_pre_The_Lion_King_-_01_-.html

A post-100hr broken-in Sennheiser HD650

High quality sample: http://www.4shared.com/music/aqc94845/hd650_post_The_Lion_King_-_01_.html

Conclusion

As previously confirmed by others, 1 2 3 4 5 6 , the physical effect of break-in is quite evident. Moreover, the psychoacoustic aspect of Sennheiser HD650's break-in has been demonstrated for ABX comparison so that listeners could verify the audibility of 100 hours of what-so-called 'warming-up'. Still, a radical sonic metamorphosing quality, of which audiophiles usually refer to, is nowhere to be seen.

Discussion

So far, there is nohing dramatic about the headphone break-in, just like the others have reported. Still, there is a chance for a reasonable doubt: how about all the claims in regards to headphone's break-in then? Did everybody really fall for such a placebo-induced maelstrom?

So another simple test conducted: This time the focus is on HD650's ear cushions.

Here's the measurement with new cushions:

Very close to the reference diffuse-field target, as measured previously.
And Below is the measurement with old cushions, about a year or two old?

Now everything makes sense: While the physical transformation of a transducer is occurring very slowly in an almost inaudible fashion, the ear cushions age relatively faster, thus making more noticeable change in the tonality. The still-firm new cushions sink deeper into the head's shape with repeated usage, and consequently, bring the transducer closer to the listener's ear.

This is such an ingenious fine-tuning technique, almost like of a musical instrument. As HD650 ages, its timbre will turn from a pronounced treble to a laid-back bass, which is a well-known sonic signature of Sennheiser. Now I can never say HD650 does not break-in.

The effect of headphone cables: SONY MDR-EX1000

Introduction

As mentioned previously, SONY shipped the US version of MDR-EX1000 with RK-EX600, a regular oxygen-free-copper(OFC) cable of MDR-EX600, instead of RK-EX1000, a 99.99999% (7N) OFC cable in order to keep the price competitive in the US market. However, because of this, headphone enthusiasts began to report the audible differences of the two cables, and of course, it was most likely that the 7N was superior in sound quality.

Is that so? In order to verify the above claim, I purchased the RK-EX1000SP from Japan for ¥4,410. From Tokyo, it took about a week for the shipment to get here in California.

Compared to the MDR-EX1000's original 7N OFC cable, RK-EX600's built quality is quite flimsy. It's definitely thinner, and the plug is made of out plastic, instead of metal; definitely looks cheaper.

Test methods

SONY MDR-EX1000 is to be measured with a regular OFC cable, a 7N-OFC cable, and finally a random non-OFC cable, while the physical placement of drivers are to be unscathed in order to eliminate such  measurement deviations. Should any differences occur, they are to be reproduced back utilizing a binaural recording method to be ABX-compared.

Test Results

Impedance

RK-EX600: there is about 1 Ω difference, with RK-EX1000's being lower, due to the fact that it is 7N & thicker in diameter.


Frequency response

RK-EX600 is 0.2 dB lower than the 7N. With the non-OFC cable, the difference is about 0.3 dB. Fluctuations above 10 kHz are due to re-positioning caused while changing the cable.



Time-domain characteristics

Spectrogram

Harmonic distortion

Subjective assessment

ATTENTION: In order to accurately reproduce these binaural recordings, listeners must use a flat diffuse-field equalized headphone, such as Etymotic Research ER-4B and STAX Lambda PRO with ED-1. The accuracy of the reproduced result can not be guaranteed otherwise.

Reference sample

http://www.4shared.com/music/8X-Fjkrq/The_Lion_King_-_01_-_Charmen_T.html

7N: http://www.4shared.com/music/eLv7LAmv/
OFC: http://www.4shared.com/music/abyYIpAK/
non-OFC: http://www.4shared.com/music/6a2J3MMz/


Conclusion

It is evident that the 7N-OFC cable's electric conductivity is superior compared to the regular OFC cable. Yet, let us not forget: MDR-EX1000's impedance is 32 Ω, which is quite high enough to withstand the damping effect of most of the portable sources' output impedance: Practically, the effect of 1 Ω difference would be infinitesimal. If this difference should be discerned by the ABX-comparison, the one must have a hell of hearing ability, or have what-so-called a golden-ear.

A lil' twt wit JH Audio

I have always wondered how custom IEMs (including generic ones that share the same design philosophy) are tuned. Recording artists use them, so they must be really good. But how good? In order to be a good studio-monitoring headphone, a product must meet the ITU's criteria; However, I've never heard JHAudio, or Ultimate Ears mentioning anything about a flat diffuse-field.  So I asked JHAudio:

"Are your IEMs made for a studio monitoring purpose, IOW flat-diffuse field referenced? Or just electrically linear?"

And I received an answer:

So it was the latter. No wonder Ultimate Triple.fi 10 pro's vocal range is receded. I'd like to thank JHAudio for taking time to answer my question.

The effect of ear sleeves: SONY MDR-EX1000

Previously, I talked about dynamic transducers having low acoustic output impedance. However, for some reason Etymotic Research MC5 had higher acoustic output impedance, hence its output sound pressure was more or less sensitive to the input load compared to that of ER-4B, the IEM with high acoustic output impedance.

Then how about SONY MDR-EX1000? Its diaphragm is made out of a liquid crystal polymer, which means more resilience than a regular PET film.

THINGS TO CONSIDER:
1. As expected, even with different bore sizes, the frequency response of MDR-EX1000 does not change much.
2. Even the foam sleeves do not lose any low-end responses with MDR-EX1000.
3. The end-correction(the horn-effect) of Comply T-500 takes its toll in the treble.
4. The end-correction(the reverse horn-effect) of Etymotic Research ER38-18 completely changes the tonal quality of MDR-EX1000.

BOTTOM LINE:
1. With SONY MDR-EX1000, as long as an air-tight deep insertion is not compromised, feel free to use any type of ear sleeves. Just try to avoid those which do not fit.

SONY MDR-EX85

Originally I really wanted to write a review on MDR-EX90, but regrettably, the pair got broken long time ago. This headphone, SONY MDR-EX85, came with SONY NWZ-S649f, and share the core design philosophy of EX90, of which SONY filed a patent in 2006.

PRO: Light-weighted. The tonal quality is far from accurate, but somehow I find it comforting.

CON: MDR-EX85 has a resonance in the sibilant-sensitive frequency range, although its degree is far less compared to that of EX700 or EX1000. Quite typical of the off-axis type headphone.

ON SECOND THOUGHT: Since its form factor is quite bulky, it is almost impossible to achieve a deep-insertion with MDR-EX85. Channel matching is quite off, possibly due to how wildly it's been used.

SONY MDR-EX1000

In the US, SONY released MDR-EX1000 with RK-EX600, a normal Oxygen-Free-Copper(OFC) cable, instead of the 7N OFC cable, RK-EX1000. That is why I had to buy the RK-EX1000 directly from Rakuten. Is there really any audible sonic difference between those cables? Well, I will talk about this on a separate article.

Anyway, on the design of MDR-EX1000: black, glossy, and sci-fi like. It is one of the coolest looking headphone I've seen in years. Even the box is so delicately designed & packaged, I was kind of scared to open it. No wonder the MSRP was 61,950 JPY. 

PRO: MDR-EX1000's frequency response is not flat. Rather, it is V-shaped; a slight emphasis on bass & treble, or ドンシャリ系の音. It can't be of a reference quality, but considering SONY have maintained this tonal quality since MDR-F1, we should just leave it as a part of their artisan spirit. Also, the distortion is almost non-existent.

CON: As I mentioned previously, for some reason, almost all of SONY's IEMs equipped with an off-axis driver show a nasty peak, or a driver resonance, in the sibilant-sensitive frequency region. While some might think this as a part of SONY's unique sonic signature, others would find it very fatiguing, and I, personally, belong in the latter group of people. 

ON SECOND THOUGHT: The ear sleeves of MDR-EX1000 are very comfortable, making deep-insertion quite easy. Moreover, SONY claim they have developed a new material, a liquid crystal polymer(LCP), to implement it as a diaphragm material of a EX1000's driver. However, what they used on MDR-CD1700 & CD2000 was LCP too: a Vectran fiber, manufactured by クラレ. And  クラレis the only manufacturer of Vectran in the world! Did they revisit their old diaphragm material and revised the design? I think I have a reasonable doubt here!

The effect of break-in: SONY MDR-EX1000

Introduction


It is generally known that a new pair of headphones must go through a "warming up(aka break-in)" phase for certain period of time before it opens up its true sonic potential.

According to Akihiko Hosaka, the senior manager at Samsung electronics Inc., who developed Samsung YA-EF310,

from http://desk.mywork.co.kr/zboard/zboard.php?id=technical&no=57

"The diaphragm of a headphone available in the current market is mostly made out of a polymer film. In this case, since this type of a headphone doesn't need a separate damper mechanism (such as a spider&suspension of a loudspeaker) implemented, I am quite certain breaking it in would have no effect at all.

 

However, manufacturers sometimes utilize a separate damper, which is made out of either rubber/urethane-related materials, to the driver of their high-end models. As this separate damper works, just like with a loudspeaker, above the glass transition temperature, its physical property might change slightly as a result of breaking-in. Should a break-in occur, it must be related to something happening at the resonant frequency."

Additionally, AKG's opinion on this break-in issue:

"...we cannot confirm that there is a burn in effect of the transducers taking place. Normally the sound of headphones changes only over many years and then mainly caused by the ear pads (less low end since the ear pads get more densely by sweat etc.).  However, during the first hours of use of headphones, the ear pads -  in the beginning a little stiff – start to accommodate to the users ears and head and the sealing becomes better, as a result the bass can be increased a little, on the other hand the distance between the headphones and the ear may become closer..."  

from http://www.akg.com/forum/index.php/topic,1736.msg5270.html#msg5270

As far as I know, internationally, there have been quite a few attempts to verify the effect of a headphone break-in, 1 2 3 4 5 6, over the years. And it seems there's definitely a physical property change occuring, but its audibility still on debate.




Test methods


A brand-new SONY MDR-EX1000 is to be broken-in for 100 hours straight with XLO's break-in sample(100 dB SPL @ peak), driven with SONY NW-S639f with all of the tone controls turned off. Once the headphone is inserted in EURI's ear canals , its physical placement must remain untouched for the next 100 hours in order to prevent any placement-related deviations. Each 10 times averaged Pre-break-in & post-break-in measurement data are to be compared, and should any type of change occur, they are to be reproduced back utilizing a binaural recording method to be ABX-compared.



Test results


Impedance

There's a minuscule amount of change at the resonant frequency, as Mr.Hosaka said.

Frequency response
Left channel:

Right channel:

Less than 1dB increment in the frequency response, and it is not under my system's measurement deviation.

Time-domain characteristics

The waterfall plots are actually two different responses of each channel superimposed on each other.

Spectrogram

Harmonic distortion

Subjective assessment

ATTENTION: In order to accurately reproduce these binaural recordings, listeners must use a flat diffuse-field equalized headphone, such as Etymotic Research ER-4B and STAX Lambda PRO with ED-1. The accuracy of the reproduced result can not be guaranteed otherwise.

Reference sample:

http://www.4shared.com/music/8X-Fjkrq/The_Lion_King_-_01_-_Charmen_T.html


A brand-new MDR-EX1000:

High quality sample: http://www.4shared.com/music/dfN6_33T/pre_The_Lion_King_-_01_-_Charm.html


A post 100hr broken-in MDR-EX1000

High quality sample: http://www.4shared.com/music/l1iijmBW/post_The_Lion_King_-_01_-_Char.html

Conclusion

As previously confirmed by others, 1 2 3 4 5 6, the physical effect of break-in is evident. Moreover, the psychoacoustic aspect of SONY MDR-EX1000's break-in has been demonstrated for ABX comparison so that listeners could verify the audibility of 100 hours of what-so-called 'warming-up'. Still, a radical sonic metamorphosing quality, of which audiophiles usually refer to, is nowhere to be seen.

Ultimate Ears SuperFi 4

I bought this headphone, Ultimate Ears SuperFi 4, in February 2011, for $29.99 from Logitech.com. I guess they were liquidating some of those unpopular models from their inventory. Fair enough.

PRO: Light-weighted. Matte metallic finish is pretty darn sick too. Drivers of each channels are excellently matched!

CON: The frequency response is not well balanced & its bandwidth is just too short, even for a balanced-armature IEM. According to Logitech, the treblt of SuperFi 4 goes up to 15 kHz: that is just not true. Moreover, the 3rd-harmonic distortion figure goes over 1% at the mid frequency range, and this amount of odd-harmonics is very likely to be detected even by normal listeners with sensitive hearing .

ON SECOND THOUGHT: Just like TripleFi 10, SuperFi 4 is just too bulky to be inserted all the way to the ideal insertion depth. And for some reason, the polarity of SuperFi's drivers are inverted! Please don't tell me this is a manufacturing error...

The Effect of Ear Sleeves: Etymotic Research ER-4B

Ear sleeves play very important role in IEM acoustics. With an adequate bore size and proper insertion depth, one might be able to get a potential performance of an IEM in full. The previous test result on Etymotic Research MC5 proved this.

However, MC5 is a dynamic transducer earphone. Generally, a dynamic transducer acts independently under the input load due to its low acoustic output impedance(constant-pressure driven), unless the driver's compliance has been reinforced(titanium & bio-cellulose & sapphire & etc) for certain purposes. Since most of the IEMs available in the market are made of a balanced armature transducer, which has a high acoustic output impedance, it is required to run the same test on a balanced armature earphone as well, to further verify the effect of ear sleeves.

THINGS TO CONSIDER:

1. Ear Sleeves of Shure & Etymotic Research are compatible to each other; not sure about the ones made by Westone. Somebody get me some Westone sleeves, then I will include them in this analysis as well.
2. Silicone sleeves offer better bass extension, due to the silicone's water resistant property.

3. Shorter the bore length, the more even high frequency response for MC5.
4. Wider the bore diameter, the better treble extension for MC5. 

5. A balanced armature transducer, in this case Knowles ED-9689, reacts to the input impedance more or less sensitive than a dynamic transducer, MC5; possibly due to MC5's helmholtz resonator equlization?

BOTTOM LINE:

1. Personally, I would like to choose clear sleeves among silicones, and shure olives among foams. Of course, all these can be achieved, only with proper insertion depth.

The Effect of Ear Sleeves: Etymotic Research MC5

Ear sleeves play an important role in hi-fidelity sound reproduction of IEMs. If the coupling of IEMs to human ears is not air-tight, various non-linear distortion inducing problems occur; loss of bass is merely a beginning. This is why IEM manufacturers include A TON of ear sleeves in their product packages so that customers can get the tightest sealing possible with their IEMs.

Of course, different sleeves demonstrate different quarter-wavelength resonant characteristics, due to the size of the bore being different. Considering the above, one can actually improve or degrade the sound quality of IEMs by simply changing ear sleeves. A rule of thumb: decreasing the bore length & increasing the bore diameter shifts resonant frequencies to higher frequency range, and vice versa.

Here's Etymotic Research's MC5 with different types of ear sleeves:

THINGS TO CONSIDER:
1. Ear Sleeves of Shure & Etymotic Research are compatible to each other; not sure about the ones made by Westone. Somebody get me some Westone sleeves, then I will include them in this analysis as well.
2. Silicone sleeves offer better bass extension, due to the silicone's water resistant property.
3. Shorter the bore length, the more even high frequency response for MC5.
4. Wider the bore diameter, the better treble extension for MC5.

BOTTOM LINE:
Personally, I would like to choose gray sleeves among silicones, and shure olives among foams. Of course, all these can be achieved, only with proper insertion depth.

Etymotic Research MC5

I bought this headphone from Amazon during the Black Friday special sale, for $46.99. The sale only lasted for a couple of hours due to the limited availability. Was it worth my money & the anticipation?

PRO: IMHO, the best bang for the buck. For this price range, you can never get a headphone with this accuracy. (The helmholtz resonator equalization is brilliant!) Moreover, the distortion figure is beautiful- it is almost non-existent.

CON: MC5's frequency response bandwidth is quite limited, compared to Etymotic's reference model, ER4. Still, the headphone performs much better than other dynamic driver-equipped IEMs!

ON SECOND THOUGHT: There is a way to extend the frequency response bandwidth, by using different ear sleeves. Changing the quarter-wavelength resonant property by modifying the length & diameter of the bore will effectively shift & distribute peaks evenly- Here is the detail.