Beyerdynamic T 51 i and T 51 p On-Ear Sealed Headphones Measurements

Click on graphs image to download .pdf for closer inspection.

Raw frequency response plots show a 10dB bass hump centered at around 120Hz, and extending upward to 300Hz. This is the predominant artifact in listening as the bass blees excessively into the midrange and makes for a bass heavy listening experience.

Midrange 300Hz to 2kHz slopes downward 4dB, which is continued by a slightly too short concha peak at 3kHz. There's good argument for a -5db warm tilt overall on a headphone, but this is significantly steeper than that as can be seen on the diffuse field compensated curve above. A treble notch 5-8kHz ensures this headphone never sounds piercing, but warm tilt goes away here; above 3kHz plot contours are about right for a flat treble response, but for a slightly bright 10kHz peak. This tends to give a little sparkle to the otherwise warm response.

30Hz square wave shows significant sway back from lack of extension and phase shift below driver primary resonance, which can be seen as the peak at 12Hz in the impedance plot. This results in a loose and distorted bass below 100Hz, but is quite understandable in a headphone of this size and type. For me, the bass bleeding into the midrange was more of a problem.

The slight upward rise of the 300Hz square wave is indicative of it's midrange warm tilt. initial transient should be higher and is somewhat misshapen with noise. This probably evidences the grainy sound heard in listening.

Impulse response too shows a low initial transient and relatively high amount of subsequent noise. Noise appears quite periodic so is likely due to the resonance at 10kHz seen in the Raw FR.

Other than a moderate and likely not too audible bump at 2kHz, distortion is fairly low. Increases in bass distortion below driver resonance in this type of headphone is the norm; this headphone looks a bit better than average.

Impedance plots shows a significant primary driver resonance at 120Hz, and a fairly strong resonance at 2.5kHz. Nominal impedance is around 40 Ohms.

Isolation is slightly above average for a headphone of this type at -22dB broadband.

Needing 35mVrms to achieve 90dBspl at the ear this headphone will be driven to solid levels by a portable device.

beyerdynamic Inc. USA
56 Central Ave.
Farmingdale, NY 11735
(631) 293-3200

Impulse's picture

For portable on-ears that's a deal breaker for me.

Impulse's picture

The newest ER4 iterations are still missing from their respective list btw.

jpelg's picture

Was sad to not see a Beyerdynamic booth at this year's CanJam in NYC a few weeks ago. Not sure why, as their oofice is local & Peter has supported the smaller NY/CT-area meets in the past. Would have liked to hear the new-ish Amiron models, as well as the newer DT1770/1990 Pro models for comparison.

Beagle's picture

A headphone review that starts out like it's going to be great, but when you get to the sound, well it's not...but recommended anyway. It also reads like the sonic comparison is against the absolute, rather than others in a given price range. It used to be that a headphone with as many "flaws" as the T51i seems to have would get a pass.

Impulse's picture

I never viewed recommended as a high honor, and Tyll doesn't tend to review any really awful stuff (and he's expressed why several times)... If you go back thru reviews there's loads of 'Recommended', even Buyers own DT-880.

If you put it in context, it's 'Recommended' but he still has like three other similar cans within the same price point that made it to the WoF over it. That says it all for me really...

The Federalist's picture

I think Tyll is dead on with this. Contrasted against the stuff Tyll is "probably" usually listening with (i.e. Utopia, Elear, Ether, HD800 etc...) the T51i sounds congested and closed in with a lackluster treble.

But its not trying to be a reference product. Taken on its own terms, for a small portable headphone that sells for less than $200 it really is a fun headphone with an enjoyable tone and is great for when you are out and about. It's indestructible, works with an iphone right down to controlling playback, and gives you a good warm tone with plenty of body to sink your teeth into.

I actually spilled a cup of hot coffee on mine. Took the cups off the gymbals and did my best to cotton every last drop of moisture out of them that I could.... Let them dry for a day, fired it back up... Disco! Kept on trucking like they didn't miss a beat.

I had an Audeze Sine that in audiophile terms sounded better. More accurate, more detail and treble. But it was high maintenance.

It was too hard to drive, felt too fragile and I never felt comfortable taking it out of the office. I throw the T51i in my backpack everyday without a 2nd thought because I know it won't break.

Sold the Sine, still use the T51i nearly everyday.

Adam Qs's picture

Totally agree. Despite shortcoming they are probably the most enjoyable cans I owned.
It's sometimes really hard to say what's better in this hobby.
There are so many cans that are 'technically' much better than what I use but they left me completely unimpressed.
I think the best example is Oppo PM3 which I could not get to like despite amping them with the best stuff.
Still, I respect Tyll's opinion more than any other as it guided me to few very good purchases (and away from some terrible ones )

gibtg's picture

Thank you Tyll for this mid-fi review. This review is far from a waste of time despite what some others may be saying and I've been awaiting your feelings on this headphone for quite some time!

On a side note, has anyone heard the DT1350 with the T51 pads installed? Good 'ol Dale Thorn reported that give the DT a sub-bass boost which it likely can benefit from.

Also Tyll, could you please add the DT1350 measurements to the resource list on the website? It has been lost in the shuffle somewhere. Thanks,

happiness_ur's picture

for me,I like T 51 i better.

Steve Levey's picture

I've had a pair of these really comfortable headphones for a year and a half and my experience showed me that these cans need quite along break in period for an appropriate bass to treble balance to occur. Yes, they are initially simultaneously, quite vibrant but with an over bass voice. However it does "recede" or simply loose it's emphasis over as they break-in. Terrific headphones. Initially I bought these as recommendation of What-hifi mag, who thought these were best cans in it's price range. Again, from my experience, this is a trustworthy mag. And while the review was also a bit mixed, still their comfort and clarity do them justice.

stalepie's picture

It's strange to read this. I thought you'd passed up reviewing it years ago. I got it as a Christmas present but never quite liked the sound of it. It seemed pop-oriented, but not very versatile. I think I've discovered monitors are more my thing, because I read your review (and plenty of others') of the older DT1350 and got that and have been happy ever since! The T51i was more comfortable though (less clamping pressure, softer pads), but I also like the single wire which has a stronger plug, too, and (if you want) a headband that splits at the top (I don't know why they would provide the same style for T51 but not allow it to split). To my ears the DT1350 is much more even and smooth sounding, while the T51i is bumpy and doesn't provide nearly as strong of sound when amped.