Sennheiser HD 25-1: Small, cheap and effective restoration.

In my (from time to time) series with tech DIY guides (like the Pacemaker SSD upgrade) I will here post you a quick shorten/overview guide of my latest mini project. So here you go Sennheiser HD 25-1 (purchased some what 15 years ago) mini makeover.

I believe this post is for a smaller group of (nerdy) people, so I will write it in English. Enjoy!

Intro – why this restoration is needed:

  1. Glitching/loose headphone contacts.
  2. Very old and ragged/torn earpads/headpads
  3. Only 3,5 mm tele plug.

1. Glitching contacts

  1. Unplug the glitching contact (red or black) from the capsule (in my case, it were the red one).
  2. Careful put a thin needle down in the socket and push the small wire/spring a bit to the middle.
  3. Put the contact back in to the socket an test the headphones.

This video explains it very well:

2. Earpad restoration

2.1 Old look

This was old earpads. and yes not even usable at all in my (anyones) opinion.

old earpad1 old earpad2
old earpad3

 2.2 New ones

If you are struggling with the new earpads to fit your capsules. I unfortunately think you are do it in the correct way. I sat down for a few long minutes and even (carefully) used a fork before I got them in place. Maybe because I bought the non-original from Zomo, but then I got new headpads “for free”.

Finally I got them on the capsules and I am quite pleased with the result. Even if the headpads were a but cheaper looking then the originals. But as I mentioned, I think of them as free goods 😉 Hint: After a while the upper head bands lose the grip, so put some extra strong glue on ut right away.

New earpad1 New Earpad3

3. Tele plug upgrade

Tools I used: Solder iron, solder, solder stand, nipper, a knife (in shortage of a wire stripper), new phono (6,3) stereo plug …and thats it.

Tutorial (sorry for the image quality in this video):

After good layer(s) of electrical tape I finally got it all in place.

Test sound:

No just kidding.

Use something like this instead to check if the soldering is correct: “Left and Right Stereo Sound Test”



Final result


Bonus: Sennheiser HD 25-1 history

(Update 2021-08 – To a new URL, from the old: )

Posted in Guide.

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