Just when you thought that the review is done, there is yet another page where I’ll tell you how to do a HD558 to a HD598 conversion.
The problem with the HD558 mainly lies in the fact that it doesn’t have as full of a midrange as the HD598. If you like things simple, you can just get the HD598 and instantly get the better sound. Of course, when these things hit the stores, the two of them may differ from anywhere to $50-$90 (just a rough guess). So, for those of you who dig black color, or want to save some money, here is how you can turn the HD558 to a HD598 twin brother (very close, but not quite a 100% identical).
First, gain access to the inside of the housing assembly by removing the pads, then the three screws that holds the driver assembly to the housing.
Opening up the HD558 and the HD598, I noticed that the two drivers looked very similar. And looking at the part number, they are indeed identical! Then I moved my attention to the housing. The housing construction is mostly similar, with the biggest difference being the black rubber tape material in the middle of the HD558 driver screen. So I tried to remove that. After removal, you’re left with a very similar housing screen that differs slightly in their honeycomb structure. I left the rest of the housing intact, and installed back the housing and the pads.
So how does it sound? Removing the black tape material gives the HD558 the boost in midrange that it didn’t have before. It’s almost similar to the HD598, except that the HD558 now has just a tad more midrange than the HD598. Just a tad more, and it’s probably better in my opinion. The two headphones now sound like they are the same model but offered in different color schemes!
After more listening, I can outline the main difference between the stock HD598 and the modded HD558. The HD598 is slightly brighter sounding, and the treble feels more open with more linear extension to the top frequency. I don’t know why this is so, considering they have the same driver, the better housing construction of the HD598 doesn’t get in the way of the driver potential of showing a more open treble. On the other hand, the modded HD558 has slightly more bottom end body for a weightier vocal and more punchy bass. I think the advantage of the modded HD558 will be more beneficial for the majority of music listeners, while the more open HD598 treble only for instrumentals and classical listeners.
The soundstage performance of both headphones are very similar, and also very good. While the HD650 still has a wider soundstage and slightly better separation, the HD558/598 has a better integration between the left and right soundstage and an added depth in comparison to the HD650 soundstage. Though the HD650 still ultimately gives the better feel of the ambiance, I just want to show that these two new headphones from Sennheiser are very good performers.
I also think that the old mid-fi soundstage king that is the AKG K501 has also been dethroned. Compared to the HD558/598, the K501 still has a bigger soundstage, but that’s about it. The HD558/598 has a much better overall soundstage performance, giving some real depth in the soundstage where the K501 sounds two dimensional and flat. The ambiance in the recording is also much better felt on the HD558/598 when compared to the K501. And when talking about frequency balance, again the HD558/598 just stomps the K501 with a more musical presentation and a better bass and midrange (I’m using the Grace m902 which is one of the few amp that can give the K501 a “proper” bass, but it still comes out fairly lacking). Technology does progress to the better.