I recently picked up some very lightly used HD 518s from one of our members in the classifieds section. They sound good - really good. So, of course, I figured I would spend a some time taking them apart to see if they could be modded to sound even better.
There aren't a lot of members here with HD 518s, though we see a lot of 558s and 598s. Opinions vary; some who have heard them all think they're very similar, and others seem to think the 518 is crap. There's a bit of a stigma around the 518, which probably comes from the 515/555/595 series. The 555 and 595, as we know, share a driver. The 515 has a lesser driver and isn't in the same league. It's been assumed that that's true of the newer 5x8 lineup as well.
Because the 555 and 595 are so similar, it's possible with minimal effort to mod the 555 up a notch. I was hoping the same might be true of the 558/598 series, and indeed Headphonia has an excellent review of the 558 and 598 here, where they find that they do share a driver: http://www.headfonia.com/sennheisers-new-hd558-and-hd598/
But there's still not a lot of talk about the 518, and I hadn't seen a teardown online. So I started gathering what information I could, including graphs from Headroom. These in particular made me suspicious:
I included the HD600 because we know it doesn't use the same driver. The breakup in the high frequency is completely different for that driver, but the other three all follow very similar curves. The midrange behaves a bit differently, but given how close the 558 and 598 are, it's not hard to imagine the 518 could use the same driver with a similar degree of earcup tuning.
These two are much harder to argue with:
They're almost superimposed on each other. So I figured there was a good chance they used the same driver. I finally got a chance to take mine apart, and I snapped a picture of the driver's part number:
Compare the part number (93481B) to the part in Headphonia's review. Exactly the same! That's pretty exciting. So even if you assumed the HD 518 had a different driver like the HD 515, maybe don't tell people that as if it's a fact. Just saying.
So what about modding potential? Here's the inside of the earcup:
If you reference Headphonia's review you'll see that the inside of this enclosure looks more similar to the HD 598, but the outside is a closed plastic mesh. And it certainly doesn't help the sound... they do sound a bit more muffled than I like, and there can be a bit of resonance, especially around certain vocal frequencies. If it were possible to get a replacement grill from Sennheiser we'd be pretty close.
I called Sennheiser and it's possible to buy just the HD 558 earcup pieces for about $18 + shipping for both sides. Unfortunately replacing the earcups isn't completely straightforward. The cable running to the other driver through the band has to be desoldered from the PCB that the jack is mounted on, and you'd have to desolder the driver on the other side as well. And then you'd end up with black earcups that probably look a little funny when connected to a black headband by beige arm. Replacing just the grill isn't very easy either, as the clips holding it to the plastic shell (about 12 or so) all have a spot of hard glue on them. That might be a little more worth it than the whole earcup, though.
Modding the 518s "up" to the 558 or the 598 isn't as straightforward as pulling some foam off the grill. If you're planning on buying the HD 518 and replacing the grills with replacement HD 558 grills from Sennheiser, you're going to spend almost as much as you would for the 558 and go to a lot more trouble. I really can't recommend that.
On the other hand, the HD 518s are *not* the dog the HD 515 apparently was. They sound very good to my ears (I'm using a y2 DAC and a M^3 amp to drive them) and I don't think buying them is a poor choice in any respects, especially considering you're getting the same driver as its more expensive buddies. I have my HD 580s as a point of comparison (also grill modded with HD 600 grills) and I feel like the 518s were very worth the price I paid.
Right now on Amazon:
HD 518: $130
HD 558: $180
HD 598: $250
As usual with audio, you're almost certainly not getting twice the headphone by getting the 598 over the 518. The 558 might be worthwhile - I don't know, because I've never heard it.
Thanks for reading!
Edited by johan851 - 10/31/12 at 2:31pm