Massdrop Sennheiser HD58X


Man, that is a long and detailed read for $150 pair of cans…though they are a special pair, especially at the price.
I was just looking for/trying to follow the link to a graphic of the felt mod. But it might take all day to find that buried in the review/specs/measurements.

Anyway, some interesting reading…for when I have a spare week with nothin’ to do :wink:


@Hellenback, Here is the link to 58x felt mod.

Any suggestions for equalizer settings for the 58x? I’m playing with the ES100 and these.


PDF of felt mod.


Cliff’s notes version.

  1. Buy some 3/4 inch self-adhesive felt furniture pads. I used these. Note - thickness matters.

  2. Drill or punch a 3mm hole in the middle. Go slightly smaller in 0.5mm increments to get less bass/more treble, or bigger for the opposite effect.

  3. Remove the cables and remove the outer cages by hand, starting by prying off at the top (it helps to have fingernails)

  1. Adhere the felt pads to the back of the magnets

  1. Replace the cages. When you do so, keep the stock foam. Despite what a famous YouTube reviewer said, removing it has no effect on the sound, and it also allows dust into the driver.



@pwjazz is the go to guy for EQ. He’s been especially hard at it EQ the HD58X.


I used felt from Hobby Lobby. It does smooth out the sound, I think, but I don’t have a Sennheiser 6 series to compare it to. Still, for $150, these are really nice. Maybe this summer when classes let out I will audition a 600 or 6xx for comparison.


Thanks for direct and simple to access directions

I appreciate the other replies (but they pretty much sent me to the review tome that had me :woozy_face:)

I do have some round felt stick-in pads but need to check if they’re the 19mm in the linked photo.

I’ll try to report back my personal experience when I get around to the mod on the 58X.

But in regard to the HD650/XX…
IMO, after many hours over years with the HD650, they hardly need any “less” of anything. Though I suppose I’ll need to listen before I pass final judgement.

Thanks again @pwjazz for the “quick & dirty” directions; it’s exactly what I was looking for👍


I finally got around to opening up the HD58X today. Have plenty of furniture felt in the garage and starting hacking away at it. I think I made my hole size about 4mm. It’s not very clean cut though as furries are cover parts of the hole. Will have to measure it a little later.