Sennheiser HD 25-1 II and adidas Original HD 25 Page 2

Sound Quality
The HD 25-1 II has a lively, articulate, and well balanced sound. Bass extension is good for headphones of this type (as long as the seal is good), and the bass is tight and clean. The mids are well proportioned and nicely integrated with bass and treble. The upper mids and treble are slightly forward, and the highs can be somewhat grainy and hard sounding at times, though not excessively so. I would characterize these cans as having a very good "pro" sound.

The dynamics are excellent with these headphones; soundstage and coherence are good. I was pleasantly surprised how good they sounded directly out of my iPod, playing plenty loud and clear. They improved with better amplification nicely, but there's a limit of how much improvement can be had with small, sealed headphones due to their acoustics.

I spent a good bit of time listening to the similar and $100 more expensive Beyerdynamic DT 1350. Though I personally preferred the smoother and more laid-back sound of the DT 1350, I also felt it was the more colored of the two headphones. The Beyer is warm and somewhat muffled sounding when compared to the livelier, but harder sound of the HD 25-1 II, and it's a little more uneven sounding than the Sennheiser, as well. While I think audiophiles would prefer the DT 1350 for music listening, pros and DJs might actually prefer the Sennheiser for its better enunciation and incredible durability.

Fit is important for the best sound and isolation with these headphones, careful adjustment will be rewarded with tighter bass and cleaner highs.

This section modified Mar 9, 2012 after new measurements.

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

Raw frequency response measurements show these headphones seal fairly well and reliably. Bass is slightly rounded and emphasized to 200Hz, then fairly flat to 2kHz. I like this curve for these cans, it gives them a solid bass response even when they aren't quite sealing, and mids that are fully present throughout. The subsequent roll-off to 6kHz is typical and likely heard as fairly flat. The peak at 8kHz is also somewhat typical of headphones generally; I hear this peak in listening as slightly too bright in this area. Highs remain fairly strong after 8kHz, and are about the right level. This frequency response curve is a good result.

30Hz square wave shows a slight bowing as indicated by the bow in frequency response from 10Hz to 300Hz.

300Hz square wave shows slightly more overshoot than I'd like to see; the upward slope thereafter shows a strong upper mids response, which tends to deliver a punchy sound. Both 300Hz square wave and impulse response show some high frequency ringing. I think this may contribute to the grainy sound heard during listening.

THD+noise measurements indicates good power handling and tight bass response. The distortion peak at 5kHz is a bit disturbing and again may explain the somewhat grainy, hard sound at times.

Broadband isolation at -17dBspl is quite good, and with 70Ohm impedance and 48mVrms to reach 90dBspl loudness, these will make good headphones for enthusiasts to use portably, and for pros to use on loud environments.

The more I listen to the Sennheiser/adidas original HD 25-1 II the more I like them. Not only do these cans deliver a punchy and exciting listening experience that's true to the recording, they're also built to take a beating, and will do a good job keeping the din of the world at bay while you listen to your tunes.

Whether you're an audio professional, DJ, headphone enthusiast, or just a plain old music lover, I highly recommend these headphones.

1989 Manual for original HD 25 and newer HD 25-1 II and HD-25 SP II.
Headphones are strong in this Sennheiser 2010 financial position press release.
Cool U.K. custom paint jobs on DJ headphones.
A review from the DJ perspective at Scratchworx.
Head-Fi threads here, here, here, here, here, and here.

Sennheiser USA
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Old Lyme, CT 06371
(860) 434-9190

Armaegis's picture

Speaking of colour scheme... is my monitor playing tricks on me or does Tyll seem a little more "yellow" than usual in this video?

Any chance you could get your hands on the 600 ohm version to do measurements? Heck, I'm not even sure where you can find one of those in North America.

MayaTlab's picture

Hi Tyll,

Thanks again for that review.

You mention the fact that the DT 1350 sound relatively to the HD-25 a little muffled. Is it with the TTVJ Slim and an iDevice ?
Have you ever heard the ALO RX ? I ask this question as I read reports that it is slightly clearer than the TTVJ - In that case it might be a better synergy with the DT 1350.

Tyll Hertsens's picture
I was using a HeadRoom desktop off a computer. Dunno about the TTVJ vs. ALO.
Kool Bubba Ice's picture

This sounds like a very friendly head fi type review. I was a bit surprised that you put the HD25 in such high regards since they are 15 yrs old & substandard compared to modern headphones like the 1350. They are 15 yrs old. You, yourself, have stated that modern headphones are always better. This is what you said, when you used the analogy of your bike 'daisy.' Why the change of heart? & then you think the 35 yr old 340's sound very good! How can they Tyll.. According to you they would be obsolete compared to modern headphones.. The analogy did rub me the wrong way cause it couldn't be further from the truth. Not including the originator & reigning champion in the mix, 73 yrs & counting, doing the DT48 a real disservice, regardless if you like them or not, they are the only headphone to actually serve a purpose outside of music. That is why they will last many yrs longer, after the STAX 009/HD800 are yrs out of production.

inarc's picture

Are you trolling or just an idiot?

"You, yourself, have stated that modern headphones are always better."

He didn't state that. Nor did he insinuate with his bike analogy that newer products are always superior to older ones.

"[...] then you think the 35 yr old 340's [sic] sound very good!"

He didn't state that. He described them as "a painful chore" and "confused and edgy".

"As you well know Hitler killed over 600 million jews [...]"

Hitler didn't kill anywhere near 600 million people.

Tyll Hertsens's picture
Kool Bubba Ice's picture

Ok.. Let's stay on topic. You are one vile human being..

DigitalFreak's picture

Hi Tyll nice review as always. Speaking as someone who owns both the 1350's and the Hd25 I'm a little surprised by your review. I'm nowhere near as experienced as you of coarse but to my ears I wouldn't class the 1350's as warmer. I personally found the HD 25's had the trademark Sennheiser lusher fuller sound while the 1350's sounded far more leaner with better detail across most frequencies. The area I thought the 1350's especially excelled in was the bass response. Although I found the HD 25 easily had more authority behind it's bass the DT 1350 went deeper with far better detail in the bass. Another strong suit for the 1350's is the vocal's on most songs really sound incredible while the HD 25's seem more well distant and fuzzy (sorry I don't know how to explain it any better maybe veiled would be a better word of description).

As for the comment of the 1350's being colored yeah I guess you could say the 1350's could be considered more colored personally I consider them more fun sounding that way. For treble response I don't think either of them especially do anything to special. Not to say either of them are bad in treble on the contrary they both do a very good job it's just nothing that really stands out or at least not in my mind. I wish both cans had a little more sparkle in the treble area. My personal view is the HD 25 is probably a far better all arounder while the DT 1350 will excel with certain music. I would easily take a DT 1350 over the HD 25 for progressive rock jazz soul or brass band music without a second thought.

Quick question Tyll in your opinion which headphone do you think has better depth of sound stage?

Reticuli's picture

Adidas has a huge history with techno djs. Very popular brand in the community. Makes a lot of sense.

NoPerfectHeadphone's picture

Can the ear pads be changed to bigger ones? Like the Sennheiser HD25 SP? Are they compatible to each other for cables? Thx!

NoPerfectHeadphone's picture

I went to try out the HD25i-ii today. Even if the HD25i-ii felt less pushy to the ear, but still, the "on-the-ear" cans wouldn't provide me the great comfort as opposed to the "cover-the ear" ones, especially for long-time wearing. I'm thus wondering if there're any bigger version of the HD25i-ii? Similar sound quality but will cover the whole ear? Thanks!

timothyolan's picture

hi, I just want to ask if there's a big difference between the "hd 25-1 ii" and the "hd 25 ii". Is the "hd 25-1 ii" the improved version of the "hd 25 ii"? I have now the "hd 25 ii". I hope you can answer my question, thanks a lot.

GoRGi's picture

Can you make review for HD25 Aluminium? The difference between HD25-1 II and HD25 aluminium.