10 clip-on (Supra Aural) headphones: comparative tests

As we promised in the past review (see "Headphones comparative tests: inserts, drops, plugs"), we are going on with the topic of headphones. This time, we'll be testing clip-on specimens not enveloping the ear, or Supra Aural according to the international terminology. This type is aimed primarily for use with whatever portable players, which determines the dimensions and weight of headphones as such. At first glance, it seems that the grown solidity of clip-on Supra Aural headphones (compared to plug-type earphones) should provide a sound quality closely on par with the "Hi-Fi" class. However, the size of transmitters in the "clip-ons" is not large enough and they lack a tightly enveloping embouchure which prevents acoustical leakage of the bass, drop in acoustic pressure etc. In theory, the lighter mass of Supra Aural does not make it possible to compete for the hi-fi pedestal on par with monitor-type headphones, heavy-weight by default. In general, the type in question is interim and transitional, so it looks like impossible to avoid compromises.

Who needs clip-on headphones? First, there are people who hate it when something foreign is inserted into/pulled out of the ears. Secondly, while doing sports activities a more reliable fastener than that in insert-type earphones is required. Thirdly, with such headphones on, your ears don't freeze in the cold! At the same time, you don't look like a big-eared pokemon the way it is while wearing monitor-type earphones.

Supra Aural, like headphones of other types fall into two subtypes: closed and open. The closed headphones, means for isolation against external noises are provided. In the open headphones, there is little that prevents sound from getting outside or surrounding noise coming into the aural tube.

We had to go through a meticulous selection to choose Supra Aural headphone models and their manufacturers for tests. We rejected those companies who purchase ready OEM-products, stick on their label, put into boxes and sell at an extra charge. The beginner companies who are just starting to operate on the headphones market were also ignored simply because the probability of making good headphones without long-standing experience is equal to chances of getting a super-win at Jackpot. A whole lot of headphones failed to pass the check for parameters which definitely did not match the price, as well as for the exterior quality. In acoustics, only nice-looking devices are able producing good sound! By the way, regarding the price: all the "clip-ons" cheaper than 15-20$ fall within the increased risk group (semi-handicraft imitations, nasty sound, low reliability)... Nor we were satisfied by any of Thomson headphones among those we got. Philips headphones showed a disappointingly high reject rate. Due to known reasons, nor exclusive models priced over 50$, e.g. the audiophile-professional AudioTechnica, were not included into our test. Nevertheless, despite the measures taken, a pair of dubious add-on models managed to get into the elite list.

Unfortunately, some headphones among those to be desired slipped off the tests because they were not available at the moment. In particular, that applies to closed Sennheiser PX200 which sell like hot cakes at shops of professional musical equipment where to the fancier's joy and delight you are allowed to listen (although at not all of them). Closed Sony MDR-Q55SL also failed to arrive in time for the test. Hmm.. It looks like the demand for closed headphones exceeds the supply: models like these are produced in extremely small quantities and are shipped among other types, with clip-ons being no exception.

During our tests, we'll reveal the prize-winners as well as specify the criteria of choosing among other models and manufacturers on your own.

Packaging

The small boxes and celluloid/plastic boats do their major job - protection against damages during transportation - quite well. The coloring of the paper is too eye-catching, even tasteless. Only the exterior outfit of Sennheiser package, as well as some expensive Sony models, can be regarded as gifted and stylish.

In the sever environment of Russia's reality, the most important thing in the headphones package is the reconstructability of the original look. Most headphone models require trying on, and much more sales assistants are reluctant to unwrap the sealed package. They are strongly against the endless crowds of buyers wishing to try it all on because what's the point of selling the goods with the package unsealed.. When you buy a pair of shoes for yourself, does it really matter for you if the box is wrinkled or not? Thank goodness that headphones have nothing to do with underwear, otherwise - dear salespeople, please let us try it on either! The package that is best suited for sales in Russia is that for KOSS, Sennheizer, and Pioneer headphones. But Sony has invented the fashion of soldering their creations tightly. Without rhyme or reason, Panasonic and Philips suddenly surprised with their peculiar methods.

Specifications

(including the data declared by the manufacturer)

Well, let's get down to business. Don't take the frequency range values presented by manufacturers for granted! How it was measured is a great mystery. I am bringing in almost all the parameters indicated on the package just to relief my conscience: they are over-corrected by marketing people to either sides. Don't mind the power readings at all.

Of all the listed parameters, most close attention deserves only the nominal resistance. As is seen from the table, the resistance values in some models are not quite player-oriented. Remember that the headphone output to MP3 players is mostly aimed at 16 Ohm. The increased resistance will inevitably result in a noticeable decrease in the sound volume, which is not critical for players with a very powerful output. On the other hand, the "resistive" headphones will make friends with the computer sound card (32 Ohm) and Hi-Fi components even with minimum distortion. The interim headphones of 24 Ohm resistance should please whatever listeners. Anyway, listening will tell. But the 60-Ohm are already a bit harder to cope with for a player - to damp the noise of the underground train, and the battery charge will be eating up much faster. At the same time, 60 Ohm is not that awful, but at 150 Ohm many portable players are losing.

I will not repeat what this or that parameter stands for, because I told about it recently.

The finest point as before is still behind the scene - with one audio source the headphones will sound at all their best, which is not the case with the other source.. Well, they haven't yet invented (not approved) such parameters to forecast this situation.

Technical solutions and design

All very well know the structure with vertical clamping arch that runs on top of the head, but there is one annoying thing - it's quite difficult to put a cap on. And that also spoils the hairdo.. Pressed by requests from consumers, the developers without much trouble invented a horizontal arch which is fastened by support on a collar. To keep the neck from too much pressure and from sliding the device down, they additionally invented hooks through borrowing the idea of hearing-aids. This solution has gained much popularity these days. In fact, the structure has proved misleading. The problem is that human necks are so different: some have necks as thick as that of a well-fed bull, others' necks are like those worth of inquisitive and feeble botanists. The height of location and the angle of slope of auricles are also variable within wide ranges. Wide-eared have quite a hard life. While the vertical arch allows quite a simple and reliable adjustment mechanism, the horizontal adjustment proved much more difficult. It turns out that the slope and pressing have to be adjusted simultaneously. As a result, it's better not to buy the absolute majority of headphones with the newly-fledged horizontal (or falsely curved) arch without trying on.

Apart from the arch, Supra Aural have enough of other tricks! The struggle for losing weight is going on diligently and successfully. Now light but strong neodymium magnets have come into play. Aerospace materials being sent to retirement will eventually force out the trivial plastic. For now, a steel "core" at the the head-band is highly desirable, but not in terms of strength. It is of paramount importance that all the joints be made of good alloy steel or, at worst, of shockproof plastic.

The compact sizes of Supra Aural headphones are achieved not only due to the reduction of sizes of dynamic heads. Each respectable company strives to patent the best folding mechanism. For now, that is best done by Sennheiser and KOSS. In the former, the cups of top-end headphones can be turned by 90 degrees thus providing a small depth in the folded state (the casing fits well inside the shirt pocket). The latter has developed not only a perfectly folding strong structure, but also (in the missing Sporta Pro model) has made the arches turnable both horizontally and vertically at the user's choice.

The implacable Sennheiser has gone further and introduced Duofol diaphragms of spiral reinforcement that substantially reduce the parasitic own frequencies of oscillations. There is also another advancement - the development of a special deflector for sound frequencies balanced over all the range of operating frequencies. The deep and distinct bass - in particular, in Sennheiser PX100 being tested – is provided at the expense of a double damping with polyurethane and perforated materials.

The generous KOSS is introducing unique materials as applied to domes, but is especially keen about titanium and its composites. The forward-looking Pioneer is not stingy for soft and tender plastic contacting the body. By the way, in SE-E33 the company providently implemented a three-stage adjustment of ear hook level due to which people of various ear size will not feel uncomfortable.

Use of cable of anoxic copper has become a rule of good form in the world of headphones. Sony is traditionally working hard at reinforcing the cord and making it "noiseless".

Alas, the "caps" of Supra Aural embouchures is almost always made of material similar to foam-rubber. As practice shows, in about five years of intensive use will wear the caps of regular foam-rubber through. The honest Sennheiser suggests that they should be replaced with the efforts of the nearest dealer. In Russia, it is still difficult with that. Other companies are silent about this problem. Equipping even the most luxurious products with interchangeable embouchures is the rarest exception to the rule. They might have been made of leather like in Sennheiser PX200 model!

What I do like Sennheiser for is the sincere care about the consumers. For example, how to not mix the left and right in the darkness? But if the eyesight is no longer perfect? Headphones by this company always have a bulging mark on the left side. Of course, if the cord is connected to one of the headphones only, then from the manufacturer's viewpoint the problem is solved automatically. Or, take another thing: many headphones are famous for hooks which mercilessly irritate hair. Few manufacturers think about this issue.

The photos will tell and show all about the design.

Measurements

Measuring the absolute frequency response (frequency response and phase-frequency variation curves) for the headphones is an ungrateful job because the systematic error is rather high which depends on the bottlenecks of the method being used. Nevertheless, within one comparative test for a SINGLE type of headphones, it is quite possible to compare the produced frequency responses correctly enough. Even in this case it would be better if the interpretation of measured frequency response be handed over to experts.

The measurements were performed with a hired LspCAD Std 5.22 which, provided an expert approach is used, gives results that are very close to those presented by respectable glossy "Stereo&Video" magazine. The headphones being tested were plugged in to a professional amplifier, with the volume level set to 30%. The reference level of the signal registered by the professional card was set to approximately -3 dB (peak) based on the loudest headphones of the test. By the way, opposing high-quality professional headphones demonstrated an irregularity of the frequency response curve by merely 10 dB (within 20 Hz to 20 KHz), and the "bends" were found solely in the right frequency ranges. Moreover, no decline at frequencies higher than 16 KHz was found. This is just to say that the suspicious tumble-down observed at the highest frequencies among the test participants is not a flaw of measurements. By the way, the apical decline measured at Stereo.ru proved very similar for identical headphone models, in general. Of course, except the distortion introduced into the frequency response by the measuring microphone and ears... We should underline it in bold: the level of low frequencies is very strongly dependent on the "tightness" of pressing in the Supra Aural headphones, that is why the real bass may essentially differ from the measured.

Important: We did not perform the smoothing of the frequency response curve which is very popular among the manufacturers! I'd better refrain myself from commenting on the phase-frequency variation (red dotted curve) so as not to complicate the perception process of those readers who are distant from the audio engineering.

Expert listening and operational testing

Activated sound sources:

• Multimedia gaming Creative Audigy2
• 6-channel audio codec ALC-650 integrated into the motherboard
• Good-quality compact disk stereo cassette receiver (combo)
• Typical MP3-player without an equalizer and timbre adjustment
• HDD Мр3-player iPod (available is a multiband equalizer )
• HDD Мр3-player Creative (integrated four-band equalizer )
• HDD Мр3-player MPIO HD200

We used the following headphones as the reference:

• Opponent – professional monsters Sennheiser 265 Linear (150 Ohm)
• Reference – those used in Panasonic (32 Ohm) player purchased long ago during a foreign country at enormous amount

The used methodology of sound quality & comfort assessment did not contradict to the requirements of MEC 268.13 (we did not do the averaging of estimates presented by various experts). To carry out the listening, we engaged people of various age, including people without a deep experience in listening. To find out if the headphones fit comfortably, they were used for several consecutive hours a day for two weeks.

I must admit, for this test we took headphones of the so-called open type, so the sound was intensely coming out to the environment. That is, it's better not to listen to music beside a sleeping person, even at the middle volume level.

32-Ohm Sennheiser headphones demonstrated a minimum dependence on the source sources. But we expected that would be 24-Ohm participants of the test (perhaps because of the price). At the same time, 60-Ohm KOSS headphones plugged in to players designed for 16-Ohm nominal load may not sound with bass as charmingly as in combination with stationary sources designed for 32 Ohm and higher. This difference is sometimes immediately felt by the ear. Sometimes, second-order bits were heard, which was not due to the level of bass but because of the value of introduced nonlinear distortion. Generally, it is a mystery what the manufacturers mean by specifying "average-nominal" or "measured-estimated" resistance in the Impedance column (remember, the electrical resistance of headphones depends on the frequency). Therefore, we should predict the sounding of the "combination" by the specified resistance of headphones with a pinch of salt. There are two major conclusions that follow from this paragraph:

• Clip-on 32 Ohm headphones can be safely used on two fronts - the portable (provided there is a powerful output to the player), and the stationary (including whatever computer audio cards).
• Clip-on KOSS headphones marked as rated for 60 Ohm will be compatible to most portable players having even the mid-powerful output, let alone the stationary sources.

In terms of stylistic preferences for insonation of rock music, I do recommend Koss Porta Pro, whereas Sennheiser PX100 - for the classical music. The "pops" etc. will get by even with middling participants of our tests.

Next. Again, Beyerdynamic headphones (of the entry-level product line, both in this test and before) failed to prove our expectations. Evidently, this eminent company is too fast at rubber-stamping mass consumption goods without hesitation to profit from the hyped brand.

Well, do the pressing-type headphones sound better than modern earplug-type earphones? While the price for "earplugs" is higher than 50$ (e.g. models Sharp HP-MD33-S, Pioneer SE-CL30, and similar with nozzles of various sizes /1/), at the sound quality some Supra Aural models being tested are even losing. And losing seriously! To name a few, only Sennheiser PX100 and Koss Porta PRO are able competing… At the same time, the boost of real power in Supra Aural is not so significant to cope with the wideband background in a noisy environment.

And what is it like compared to monitor-type headphones? I am afraid, it's not all as straightforward as it seems. The only what I can assert is this: in principle, best monitor-type hi-fi models should beat the cohort of just tested clip-on headphones at the depth and precision of basses, as well as at the linear distortion in medium frequencies.

Of special mention is that the boost of improved sound among clip-on Supra Aural headphones was observed at the 30$ level. I believe the probability of finding a sound miracle among the even cheaper "clip-ons" is laughably negligible. But, be watchful: with ~20$ (a «brand»!), you can get models both well sounding and pretty middling at all the parameters, including reliability.

The listening and use impressions have been briefly summarized in the below table in the form of "pros" and "cons". For getting a closer idea of the music material used in listening, visit http://ai.obninsk.org/relax.php3 or www.uni-scope.com.

Conclusion

**

**

The first and second places in our today's tests were shared between Sennheiser PX-100 and KOSS Porta Pro. Aha! Again Sennheiser!  – a watchful reader may exclaim. Wasn't that an order, eh? Well, if that were so.. :)) The company still even has not plans to establish a representation office in Russia, and the number of official distributors is far too few, looking arrogantly on top of the other democratic computer multimedia. As regards KOSS Porta Pro, I must admit it is one of the most successful models of foldable Supra Aural pressing-type headphones. In addition, KOSS headphones are much easier to make available in Russia than those aristocratic Sennheiser which sell mostly in the capital cities.

To my deep regret, much cheaper clip-on headphones either had a risk of unreliable structure or demonstrated a sound of much lower quality :(.

I have to give the prize for the best «price/sound» ratio to KOSS KTXPRO1 model. The drop in prime cost was evidently achieved due to the omnipresent plastics.

The prizes of sympathies come to Sennheiser PMX60 (mainly for the design and make), as well as to Sony MDR-G74SL (for the sound and smart folding).

The prize for innovation and uniqueness comes to the exceptionally interesting Pioneer's SE-E33 model.

Read also: "Addendum to the comparative tests of clip-on headphones".