Over-Ear Sealed Headphones Reviews

Generally 1More has been offering headphone in the affordable end of the spectrum. With this new headphone they're making a move into the meaty midsection of the headphone world. And an interesting move it is!

1More Triple Driver Over-Ear Headphones ($249)
The 1More Triple Driver Over-Ear Headphone is touted, heck it's named, as an over-ear headphone. Like sometimes happens in this class, however, it's as close to an on-ear as it is an over-ear. Fortunately, It's still a pretty comfortable headphone, but I'm getting ahead of myself.

The 1More Triple Driver Over-Ear Headphone is a pretty stylish affair. It's black and silver color scheme is nicely executed with above average materials at this price.

The foundation of the headband arch is a stainless steel band with a foam cushion covered with good quality black protein leather. (The web site says leather, but I've verified with 1More that it is protein leather...which is fine, real leather at this price-point would require the use of inferior materials.) The inner part of the headband pad has dimples intended to distribute weight evenly over the top of the head. I found it did do a good job of conforming to the top of my head and remaining comfortable.

Headband adjustment sliders are attached to the hinge/pivot mechanism above the yoke and appear to be made of aluminum, as are the hinge/pivot mechanism and yoke. Adjustment has medium tension and is detented; adjustment is easy and remains securely in place once set.

The hinges allow the ear capsules to fold inward for storage and transport in the included hard side clam-shell case. Ear capsules rotate forward and back on hinge assembly pivot and up and down on the yoke gimbal. Rotations move freely and quickly to conform to you head. The mechanisms seem well built; all-metal construction; and I experiences no rattling or squeaks.

Yokes are mounted fore and aft on pivots attached to the clear anodized aluminum capsule housing. The aluminum has a seriers of fine grooves running around the outside as design elements. The rear of the housing is covered by polymer "rims" (I suppose because they look a little like fancy wheel rims) under which is a clear plastic cover glass that acoustically seals the headphone.

Earpads are protein leather over a very soft grade of memory foam. Earpads are round with an 80mm outside diameter; earpad opening is also round with a 45mm opening. The 1More Triple Driver Over-Ear Headphone is touted as an over-ear headphone, but it's sort of a hybrid over-ear/on-ear design as my ears (which are slightly smaller than average) don't fit withing the confines of the pad. Fortunately, the pads are extremely soft and I found them quite comfortable for long listening.

Accessories include a four foot oxygen-free copper conductor cable with Kevlar® core and braided sheath in a "Y" configuration. Headphone end terminations are 2.5mm TRS plugs. I don't particularly like this connector, but in this case there is a well into which the connector body snugly fits that appears to be secure enough to reduce all strain on the connector itself. Left and right indicators on the cable are the color of the insulating plastic between the bands of the TRS connector plug itself; left is while, red is right. There is also a matching color plastic ring around the connector wells on the headphone capsule itself. I had no problem with cable born mechanical noise on this flexible cable.

The included hard-side clam-shell case has a zipper closure and molded interior that keeps the headphones nice and secure within for storage and transport. Also included is a 3.5mm to 1/4" adapter.

I poked around to see if I could disassemble the headphones and found the pads appear to be glued on. The center mesh panel of the pad covering the driver area does have some cushion and thickness, which no doubt provides some acoustic damping between the ear and drivers. The inner panel of the earpad is solid protein leather, but does have a small pattern of holes in the wall in front of the ear. So the pads do have a tuning feature; I see this as evidence that some significant effort has gone into the tuning of these cans.

All told I found this a pretty tidy kit: the headphones are good looking, well built, surprisingly comfortable considering they are as much on-ear as over-ear. Let's have a look at this triple driver situation.

Three-ish Drivers
I'll preface the following discussion with my experience that I've only once heard a multiple-driver over-ear headphone that I thought was any good. (The Enigmacoustics Dharma.) Other than that, they've all sounded pretty bad to me. So I'm went into this review with a great deal of skepticism.

This headphone was quite interesting to me as it uses a graphene coated mylar driver—a new material for acoustic transducers and the headphone is fairly successful in incorporating multiple drivers to produce good sound, so I wanted to dig into it a bit. I did manage to have some correspondance with the designer of the headphone on some of the technical details, and also had a phone conversation with Luca Bignardi, who did the acoustic tuning of them.

The 1More Triple Driver Over-Ear Headphone has three drivers...sort of. The main driver is a 40MM graphene over mylar dynamic driver with a nominal 37 Ohm impedance. Mounted in front (towards the ear) of the main driver is a piezoelectric ceramic plate tweeter. The third driver, mounted behind the main driver but within the sealed headphone capsule, is a passive element something like the passive radiator you'd find on a speaker. It's worth noting that the original European version of the 1More Triple Driver Over-Ear Headphone had a titanium coated main driver diaphragm. This model can be identified by the Champaign color of the aluminum housings. The latest silver colored version has the graphene driver, but the current product box still says titanium. I've been told that the headphone was retuned in the switch-over, and the mistake on the box will shortly be corrected.

We'll take the drivers one at a time.

40mm Main Driver
The main driver of the 1More Triple Driver Over-Ear Headphone has a graphene over mylar diaphragm. Basically, it's much like a normal mylar headphone diaphragm with a fixed edge around the circumference. The tricky bit here is that Graphene is an extremely stiff, material and to my way of thinking the graphene would prevent the mylar from performing it's normal flexing motion around the edge of the driver. I tried to open up the pair I have to get a look at the driver but the pads appear to be glued in place so I was unable to inspect them.

Carbon atoms can take on a number of crystalline forms from diamond to Bucky-balls (Fullerene). Technically, Graphene is a two dimensional crystal of carbon atoms that is one atom thick...a very thin material indeed.

Graphene is the strongest material ever made. From here:

Due to the strength of its 0.142 Nm-long carbon bonds, graphene is the strongest material ever discovered, with an ultimate tensile strength of 130,000,000,000 Pascals (or 130 gigapascals), compared to 400,000,000 for A36 structural steel, or 375,700,000 for Aramid (Kevlar). Not only is graphene extraordinarily strong, it is also very light at 0.77milligrams per square metre (for comparison purposes, 1 square metre of paper is roughly 1000 times heavier). It is often said that a single sheet of graphene (being only 1 atom thick), sufficient in size enough to cover a whole football field, would weigh under 1 single gram.

So very light, and very stiff...excellent properties for a headphone diaphragm.

It also has a number of of unusual electrical and optical properties, which don't hold much interest for us in this discussion, but it is worth mentioning that it has very high thermal conductivity, which may act to drain heat away from the voice coil area of the headphone that might otherwise soften the mylar and affect its elastic properties. (Just guessing there, by the way.)

Many of you may have heard of the Ora GrapheneQ headphone offered on Kickstarter as the first graphene based headphone some months ago. GrapheneQ is a slightly different kind of material. Basically, GrapheneQ is many sheets of Graphene stacked and adhered together. You can think of it like oriented strand board (OSB) structural wood sheeting.

While this material is somewhat different than graphene proper, the Kickstarter page has some great technical information including measurements of the diaphragm performance. I found many similarities between my measurements of the 1More Triple Driver Over-Ear Headphone and measurements of the Ora headphone.

Again, from the ORA Kickstarter page:

The basic idea here is that a normal mylar driver is not particularly stiff, so as it's accelerated back and forth by high frequencies it lags behind the voice coil movement due to its elasticity. Imagine waving a thin metal yardstick left to right in fromt of you. due to its elasticity it's going to wobble around with your physical input and will fight against your movements to some degree due to its physically reactive nature. If you wobble it back and forth fast enough, you will set up standing waves of vibration in the ruler.

The same thing happens in a headphone driver: If the material isn't stiff enough the driver surface will lag the input and fight the incoming signal to the coil. This will show up in the impedance and electrical phase response of the driver showing up as large deviations as the diaphragm lags the coil movement, and smaller features at localized frequencies as the driver breaks up into modal vibrations. You will also see a rougher frequency response at higher frequencies due to the modal vibrations.

A very stiff and light diaphragm will more readily move in concert with voice coil mechanical input. Think of it as a very light and stiff yardstick that you can easily swing back and forth without bending. It will lag less, which will reduce electrical phase shifts, and it will be less likely to take up oscillating modes, which will keep the frequency response smoother.

Well, sure enough, the measurements of the 1More Triple Driver Over-Ear Headphone exhibit these characteristics quite handily.

Above is the frequency respons, and impedance and phase response I measured of the 1More Triple Driver Over-Ear Headphone. Those familiar with these measurements of other headphones will readily see that above 3kHz the frequency response is remarkable smooth and free of noise.

Readers are less likely to have spent time looking at the impedance and phase response of dynamic driver headphones, but after a bunch of rooting around I came to the conclusion that the 1More Triple Driver Over-Ear Headphone has extremely low change in phase angle above 3kHz. For reference, check out the rising phase response above 3kHz of the following headphones: B&W P7; Focal Spirit Pro; Denon ADH-D2000; and Emu Teak. Even though the Denon, B&W, and Emu all have quite light and stiff microfiber diaphragms with surrounds, they show more phase angle in the high frequencies. Most other more traditional mylar diaphragm headphones I looked at show even more deviation.

Impulse response measurements show a similar trait. In this case imagine quickly moving the thin metal ruler left to right and back again stopping quickly at the end. The metal ruler will continue to wobble after you stop moving your hand. The very light and stiff ruler will stop much more quickly. From the ORA Kickstarter page:

And my impulse response measurements of the 1More Triple Driver Over-Ear Headphone:

This is indeed a very noise free impulse response. Again, compared to the impulse responses of the B&W P7; Focal Spirit Pro; Denon ADH-D2000; and Emu Teak it is remarkably well behaved, showing little high frequency noise.

So, there seems no doubt in my mind that the 1More Triple Driver Over-Ear Headphone is exhibiting the desirable properties of a graphene driver. But the question remains: How, exactly, do you make a fixed edge graphene driver that has enough flexibility to move freely?

Of course, this is a question that probably pokes at proprietary information. So I had to make a series of educated guesses to have them confirmed or not. Here's the dialog:

TH: Is the diaphragm fixed edge (like a normal mylar diaphragm) or is it a cone driver with a surround like a speaker?

1More: The diaphragm is fixed edge.

TH: If it is fixed edge, does it have an area around the edge that doesn’t have graphene on it so the area near the edge can flex better to allow fee movement?

1More: Yes, the edge of diaphragm doesn't have graphene on it.

TH: What is the diameter of the voice coil?

1More: Diameter: 20.34mm

TH: How is the graphene attached to the mylar? Is it adhered as a sheet prior to stamping the diaphragm into shape? Or is it deposited as a film after stamping? What deposition method?

1More: The graphene is adhereed as a sheet prior to stamping the diaphragm into shape.

So, a little WAG (wild ass guess) here: I asked what the voice coil diameter was because it seems to me the logical way to build the driver is to have a large central dome that has the graphene coating, and leave the mylar uncoated outside the central dome to provide the flexible suspension for driver movement. Of course, it is possible that the graphene coating extends beyond the circle of the voice coil—this might be helpful with the heat dissipation I mentioned earlier—but it also might create quite a bit of strain in the mylar at the edge of the graphene. Given that it does have a fairly large diameter voice coil, my guess is that graphene coating is only over the central dome of the diaphragm. Either way, measurements clearly show the driver as having characteristics one would expect of a well built graphene diaphragm.

(It also makes me very curious about the ORA headphone. I'll try to get my hands on one.)

Piezoelectric Ceramic Plate Tweeter
In the exploded diagram near the top of this page you can see the ceramic tweeter element that is mounted to front of the baffle plate, which is in front of the main driver. This type of driver is often used as buzzers in hand held devices, but there are wide-band versions of these drivers that are becoming more common as speakers in portable devices.

A piezoelectric ceramic element is firmly adhered to a metal plate. When an electrical signal is imposed on the plate it will get slightly larger or smaller in diameter depending on the polarity of the signal. This will force the metal plate below to bow back and forth giving it the ability to emit sound. (More on piezoelectric ceramic plate drivers here.)

I was initially told the cross-over occurred at 2kHz and was a shallow slope. In further email exchanges with the engineer I was told the cross-over point was at 10kHz.

TH: Is this a piezoelectric ceramic plate driver or something else?

1More: Yes, it is a multi-layer piezoelectric ceramic driver.

TH: What is the impedance of the ceramic driver?

1More: The characteristic of ceramic driver is similar to the capacitance and without DC resistance.

TH: What kind of crossover does it use? Simple capacitor, or something more complex?

1More: Simple capacitor.

TH: What is the crossover frequency and slope?

1More: 10kHz

In my impedance and phase measurements of the 1More TDOEH I do observe a feature at 3-4kHz that looks like it might be the cross-over coming into play, and I do not see any feature at 10kHz that might indicate the cross-over. However, going simply by the rough size of the ceramic tweeter in the exploded view it seems to be quite small; roughly about the right size for an element with a primary resonance in the 10kHz region.

Regardless, frequency response plots show a very nicely behaved response, quite continuous and close to the Harman target. Wherever the cross-over is, and whatever the bandwidth of the driver is, it seems to be well integrated and properly tuned.

Bass Reflector
In the exploded diagram you can see 'Bass Reflector' mounted behind the main driver. This element is similar to a passive radiator that can be found on small speakers, but it is different in that it is captive within the sealed enclosure of the headphone as opposed to being exposed to the outside environment.

Initially I was told that this element acted as a moving mass that provides some physical vibration to give the listener a visceral sense of bass. In close reading of the website and in dialog with the designer it seemed the focus was actually on bass tuning. Here's the email exchange:

TH: Is this driver intended to extend or modify acoustic bass response, or does it function as a moving mass to provide a physical sense of bass for the listener?

1More: The passive driver is for modification bass response.

TH: Is the cavity between the driver and glass cover sealed from the outside world?

1More: No.

TH: Is the cavity between the driver and glass cover vented and damped into the acoustic space in front of the driver?

1More: Yes

TH: At what frequency does this driver begin to have its effect?

1More: Below 200Hz

So, there is likely some damped port from behind the passive radiator to both the outside world and into the space in front of the main driver. It seems likely to me that this 'Bass Reflector' system has something to do with making the effective volume of the enclosed space within the headphones appear as an acoustically larger space allowing extended low frequency response.

But why they call it a 'Bass Reflector' eludes me. Possibly it provides some advantageous phase shifting to extend or accentuate bass response. Two things I noted in the measurements were:

• In the phase plot up the page you'll notice that below the main driver's primary resonance at around 70Hz there is an upward inflection in the curve that remains flat and above 0 degrees. It may be that the bass reflector is broadening the driver resonance.
• In my THD+noise measurements (above) there is a distinct rise to a shelf below about 120Hz. I've seen similar THD plots before, but I'm not sure I've seen one with such a distinct low frequency shelf. It could be that this is not harmonic distortion in the normal sense but some sort of strange effect from the bass reflector. We'll talk about this a little more in the 'Sound Quality' portion of the review...

  ...which will start when you flip the page.