Sennheiser HD 25-1 II and adidas Original HD 25

A classic in the world of professional and enthusiast headphones, and probably the world's most popular DJ headphone, the HD 25 has remained in the Sennheiser line-up in a small variety of incarnations since 1987 ... and deservedly so.

When I first heard them about 15 years ago there were very few expensive headphones available, so they seemed pricy at the time. They sounded great, though, and were a solid recommendation. In today's world of high-priced fashion headphones, and even higher priced high-end headphones, these very good sounding and highly functional cans seem like a real bargain for professionals and audio enthusiasts alike.

Let's take a look at the latest incarnation, the Sennheiser/adidas HD 25 Original.

Sennheiser/adidas HD 25 Original ($359 MSRP, $269 Street)
What I love about these headphones is that a quarter of a century ago the Sennheiser product team nailed great sound in the split headband design formula and they've had the good sense and gumption to stick with it ever since. Initially released in '89--which I am assuming from the original manual for the HD 25 that indicates a printing date of that year--it then gained the Roman numeral "II" in 2007, and the latest adidas Original version was introduced in early 2010.

Model Variants
I was unable to determine the exact differences between units over the years, but it appears to be very little. HeadRoom did have a pair of HD 25-1 with "Made in Germany" printed on them, which I assume are the HD 25-1 version. I would guess the pair I had are about 10 years old. The measurements were almost identical between this old headphone and the current adidas Original when I mounted the old pads on the new cans, so very little has changed over the last 10 years in terms of measured performance.

The adidas Original version is identical to the also currently available HD 25-1 II headphone, but for the color changes to the earpads and headband pads, and the adidas stripes and logo on the capsules. Both current models come with a second pair of velour pads. The roughly $50 price premium of the adidas Originals is purely cosmetic; if you're interested in these headphones and want to save a little money, just go with the HD 25-1 II as they will sound and work the same.

There are a total of six variants of the "II" headphones:

  1. HD 25-1 II - 70 Ohm impedance; 1.5 meter cable with right-angle miniplug.
  2. adidas Original - Like above, but with adidas color scheme.
  3. HD 25-II* - 70 Ohm impedance with two meter cable and straight connector.
  4. HD 25-C II - 70 Ohm impedance with three meter coiled cable and straight plug.
  5. HD 25-13 II - 600 Ohm impedance with three meter cable and straight connector.
  6. HD 25-SP II - The cheap version of the HD 25, without split headband; 85 Ohm impedance; different driver. This headphone sounds significantly different and not as good, and is not recommended.

* - no longer available.

Build Quality
These cans are built like a tank; virtually indestructible. The old pair of HD 25-1 I tested while writing this article are, and have been for a long time, popular headphones among HeadRoom employees. They saw much use around the office. In comparing the new adidas Original and the ten year old HD 25-1, other than the pads being obviously well used, I found little difference in the look, feel, and tensions of the various parts and adjustments. There were little obvious indications of wear on the matte textured outer surface of the headphones. All of which indicates a very robust design and manufacture to me.

This doesnt surprise me in the least. I've been to Sennheiser's plant and had a tour of their materials analysis lab. I've spent a lot of years with lab gear in the past, and they had some good stuff. My experience with Sennheiser materials and build quality is that it's top notch.

If you do manage to break the headphones, they are repairable and a fairly full complement of spare parts is available from Sennheiser.

These headphones are quite light and have a well designed split headband, which together provide a very secure and reasonably comfortable fit on the head. The left earpiece can swivel backward or forward for one-eared use. Though the clamping pressure is a bit tight (which is important for secure fit and good bass response), the headphones are quite comfortable and easy to position on the head.

Though the headphones do not have any folding features to make them smaller for storage and transport, they are fairly small as is, and their durability will allow you to feel comfortable just throwing them in a backpack or milk crate. Because the headphone is light; the earpieces relatively small; and the headband easy to collapse into a single slim band, these headphones are quite comfortable when worn around the neck.

The ergonomics of the HD 25-1 II, coupled with the stellar durability previously mentioned, have made these long time favorites among audio professionals of all types. They are especially prized as great DJ headphones, and are regularly given custom paint-jobs to improve their humble looks.

Evidently, for durability purposes the cable conductors are steel. Many like to play with cables, so for those inclined the stock cables can be replaced with Sennheiser HD 600, or HD 650 cables, or compatible after-market cables. See video for details.

Is it worth it? I thought I heard the HD 650 cable as slightly smoother sounding, but it was a very small difference ... small enough it could have easily been me fooling myself. I don't like the idea of stressing the connectors, but I think the HD 600 cable using the standard cable routing might be something I would do.

The isolation of the adidas Original is above average for a headphone of this type, and will perform well when isolation is needed. This is a good headphone for monitoring in loud environments.

Sennheiser USA
1 Enterprise Drive
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.