A Look at the Torque t402v Bass Adjustable Headphone

This is not a review of the headphone, but rather just a good opportunity to learn about a bit of headphone acoustics—and let my curiosity run amok. I wanted to see what the measurements of the Torque t402v looked like. With two pads having four filter settings each it took me all day to acquire the data and make the comparison worksheet. It didn't quite turn out as I expected.

151124_Blog_BassAdjustableHeadphones_Illustration_VentThe photo above show a close-up of the on-ear pads and headphone capsule of the Torque t402v bass adjustable headphone ($399). If you look at the driver capsule in the middle of the image above, you'll see a port at the top (circled in red) that vents the space behind the driver into the space between your ear and the headphone.

In the crude illustration to the right, you'll see how the sound from the front of the driver (green arrow) goes directly to the ear, and the sound from behind the driver (red arrow) goes through the vent and then to the ear. At low frequencies—where the wavelength is much longer than the path length of the red arrow—the signal from behind the driver is out of polarity with the signal in front. This will cause the signal near the ear to be somewhat cancelled out by the interfering acoustic signals. Basically, the bigger the vent, the more out-of-phase rear signal gets to the ear chamber, causing more cancellation and a lower level in the low frequencies.

151124_Blog_BassAdjustableHeadphones_Photo_BothPads

The pads of the t402v are perfectly square and can be rotated and installed in four positions. Each position has its own vent—seen as the variously colored plastic inserts in the photo above—each of which will align with the capsule vent when in the upper position.

The yellow vent has the smallest holes, giving less sound from the rear of the driver therefore yielding the most bass. The blue vent is slightly larger and should reduce bass some. Likewise the red is larger still, and the black hole should have the most air passage theoretically yielding the least bass.

And there's where things start going pear shaped. Here's the plot of the over-ear pads.

151124_Blog_BassAdjustableHeadphones_Graph_Torquet402vOverEar

As you can see, the yellow filter does indeed have the most bass; the blue is next. But when we get to the red and black settings things seem swapped. Damn. I triple checked this and these numbers are correct. Also odd is that the black plot seems to be oddly different in a number of other places. At 7kHz, for instance, the black plot is at the top when the order of traces would cause one to assume it would be at the bottom.

Care to make a stab as to what's going on in the comments?

My guess is that the fully open hole of the black vent has an air turbulence structure different than the filters with 8 holes making it behave a bit differently. Who knows.

Worse yet, when I switched to the on-ear pads...

151124_Blog_BassAdjustableHeadphones_Graph_Torquet402vOnEar

...I got very little bass adjustment at all, but for the yellow filter which has some. This may be due to a poor seal not creating a good enough chamber for the front and rear acoustic waves to cancel effectively...or not. It may be just how the graphs are aligned because it does look like the treble hump at 3kHz is being adjusted, and in the right order. When I listened to the on-ear pads, I do think I heard a distinct difference in bass response with the various pads.

I did make a little .pdf booklet of all the measurements. I found it interesting to note that bass distortion on the open ear pads increased, and/or got more erratic, as the hole got bigger. It's also fun to watch the low-Q impedance hump at 80Hz grow with vent size.

I should mention I didn't think these headphones sounded particularly good. I suspect that you may also get effects from the vent at other frequencies, which would roughen up the frequency response. I've heard four or five acoustically bass adjustable headphones and only the AKG K267 Tiesto sounded any good to me at all. Here's its compensated plots as opposed to the Torque's raw plots above.

151124_Blog_BassAdjustableHeadphones_Graph_AKGK267

Anyway, curious if you've got any ideas on the data...

...but don't spend too much effort on it, there's turkey and stuffing in need of attention!

COMMENTS
Jim Tavegia's picture

are a new generation of headphone amps that come with "Insert Jacks" for using some 15 or 31 graphic EQ to allow us to really tailor the sound to our hearing and the cans we use. If you don't want them then just insert and I/O cable for a straight feed, or buy a nice graphic EQ and adjust on the fly. After all your testing it seems with the measurements of cans all over the place "inserts" would be a great, cost effective idea. A straight wire with gain is really kind of a pipe dream at this stage of the game.

I have a 3 headphone amps from the recording industry and the ART Pro 6 has bass and treble that does help quite a bit and can allow 6 people to enjoy the same feed. It is not always enough of an adjustment, but better than none from my other 4 headphone ART or my PreSonus 4, but that unit does have a mono switch and the ability to gang as many of those as my recording session requires. I use my Focal Spirt Pros, my 2 pair of AKG K271s and my 2 pair of Sony 7506s, a pair of AKG 701s that are my main just for listening cans, and they all need something a little different EQ wise. My favs are the AKG K271 and K701s overall. A very nice balance for my hearing loss. The Focals are worth the $350, though and are a real entry into high end land I think. I will mix with those.

Seth195208's picture

: )

zobel's picture

Purt' near impossible to figure the physics in these strange cans here but, these physics are not too tough; a 13 lb turkey thaws in the fridge in a day and a half, and takes three hours to cook. Have a happy Thanksgiving.

Jim Tavegia's picture

These little mixers have nice headphone amps built it, a nice set of tone controls, plus inserts that would allow in add to the playback chain a 15 or 31 band stereo EQ for fully tailoring the frequency response to one's liking. I do wish Tyll would get one of these and give us his thoughts. They run from $199 to $399 and easily fall into the price range of decent headphone amps. He might even really like what he hears. I have made some very nice recordings with the Mackie VLZ gear.

castleofargh's picture

could it have to do with how the block sits on some positions, maybe making for an undesired opening/vent between the driver and the block?

yage's picture

Hi Tyll,

It seems your frequency response measurements are a little at odds (at least in the bass region) with the ones Brent Butterworth obtained over at SoundStage Xperience - http://www.soundstagenetwork.com/index.php?option=com_content&view=artic....

I've spent some time with the t402v and while not the best headphones in the world, I thought they sounded decent, though the dished midrange gives vocals a distant quality and makes massed strings sound a bit artificial.

zobel's picture

is like trying to smell the number 9.

zobel's picture

it's like trying to smell the color 7.

Jim Tavegia's picture

What measures perfectly, at least in terms of how and what we can and know how to measure, the best measurements don't always sound the best. The problem is really that we all have different hearing measurements, so to think that one set of cans or amps fits everyone is ridiculous. If this last major go-round to tests from Tyll proves anything it is this. Bob Katz is right in the it is all in the EQ, yet the headphone amp industry is avoiding this just giving us their version of a straight wire with gain. It is not enough. The Harman work is very important and being ignored.

Beagle's picture

....is that I'm staying far away from these.

There seems to be a new breed of headphones where the designer appears to have no clue as to what a reasonably even FR is (OBravo, Flare Audio etc). Either that, or they are trying to reinvent the wheel by making it oval.

Mr_Slim's picture

Jim, I agree that the Harman work is important, and it is being ignored. Until recently, I have to admit that I was part of the "if it needs to be EQ'd then it must be bad" crowd, but after understanding the reasoning, and the work the Tyll and Bob K have done, it makes a lot of sense to me.
However, I disagree that it is up to amplifier manufacturer's to provide the EQ capabilities, at least for those of us who have gone down the path of having our music sourced from a server. There is no way that the flexibility of something like this: http://mathaudio.com/headphone-eq.htm for $60US can be implemented in hardware. There are other free options and more expensive ones, and it may come down to the user to determine which one they like the best, but regardless, the path of least resistance at this time is to go the Software EQ route. (at least that's my plan)

Seth195208's picture

has to say about the Harman curve. I'm sure it will prove to be entertaining and informative.

Music's picture

Looks great! It shows that the vent holes mostly affect the bass and mid-bass. But I will think that it is related to the engergy, not cancellation.

elmura's picture

EQ is fine as long as you make fine adjustments. After all, people buy amps that colour the sound to their preference. But with EQ, you have far more control of the sound you're after (or response you wish to create).

As for the Torque headphones, it's a novel idea. The black port has the lowest air velocity of the lot and should make for less control over the driver. This would cause the driver to overshoot and create a looser but more powerful bass response.

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