[parrot5]

I was debating which one to buy, and after some search on Head-Fi I was still undecided, so I ended up buying both of them for comparison sake. I know cheaper earbuds like these aren't that popular around here, but for whatever it's worth, here are my impressions of them.

Testing environment:

1. Both earbuds are tested WITHOUT their foam covers. While the foam covers increase the quantity of bass frequencies, I find that they muddy up the sound.
2. Testing material is pop songs with relatively more of "real" instruments (vocal and acoustic instruments, instead of synthesized counterparts), as I find "real" instruments are more demanding, and thus easier for me to compare the earbuds.
3. Computer setup: FLAC played through Foobar2000 with ASIO plugin (no DSP) -> M-Audio Firewire Audiophile -> Go-Vibe V5 -> earbuds

Sennheiser MX500:
Coming from the MX300, the immediate impression is that the MX500 has a greater quantity of bass, along with the openness and the treble-emphasized presentation of the MX300. Bass extends deep and manages to keep the timbre details (relatively, of course). Mids are forward, and do not get muddied up by the bass (unlike the MX51, but more on that later). Treble does have some sparkles, but I don't find it especially detailed. The soundstage is wide for earbuds, and thanks to the treble-emphasized presentation it has "airness" and do not sound compressed. Overall it has a smooth, detailed, and full presentation of all ranges of the frequencies.

Sennheiser MX51:
Now coming from the MX500, the immediate impression is that the MX51 has a lot more bass! The bad news is that the lower mids are muddied up by the bass, especially the chest register of male vocals and warmer female vocals, along with the majority of strings instruments. (Ever have a pair of flat-panel speakers with a relatively high crossover? Imagine your subwoofer trying to do some of the job of producing male vocals, together with the satellites. I own a set of Monsoon PlanarMedia9 flat-panel speakers, which has a crossover frequency of ~200Hz. While the definition in the treble and upper-mid regions are pristine by multimedia speaker standards, the lower mids can't match it. The feeling here on the MX51 is very similar.) Together with a more laid-back presentation of the mids than the MX500, the lower mids on the MX51 feel recessed and muddy. The soundstage is slightly narrower than the MX500, and its presentation is more energetic but less detailed than the MX500.

Conclusions:
For acoustic instruments, I find the MX500 sounds more believable, closer to the real, than the MX51. Largely it's due to the MX500's ability to keep more timbre details, and a relatively neutral presentation especially in the mids. With a energetic and fun characteristics, the MX51 is certainly (and understandably) aimed more towards electronic pop and other bass-heavy genres. While the MX500, with its more detailed and neutral presentation, is more of a all-around performer.

Update on June 5, 2007:
Note that this review was done in a quiet environment. I find that in a noisier environment (for portable use) the MX51 would sound "better", as music has more presence than the MX500. MX500 will sound thin in comparison when it's noisy outside.
/update



Additional notes:

1. This is my first more-in-depth review of audio equipments. Any comments are welcome.
2. For fellow Chinese Head-fiers, the majority of the testing was done using Jacky Cheung's newest Mandarin album, and Faye Wong's XRCD album "Sky" which is famous for its vocal recording. Some vocal+piano passages of Track 9 of Cheung's album, where the piano and the vocal both play the melody, especially gives the MX51 trouble. I'm pretty sure the producer wants to have the listeners hear both the low vocal and the low piano clearly, not muddied up. In addition, I feel that the vocal in Track 1 of Wong's album serves as a good sample to demonstrate the lack of details and its colored characteristics in the vocal region.

 

[shikitohno]

thanks for the review! I've been always wondering how the new sennheiser earbuds stack up with their predecessors.

 

[Aidanael]

Nice review !

 

[penguindude]

I always felt the mx51 extremely lacked bass.

 

[swissporky]

parrot5, Have you been able to hear the Yuin Pk3 yet? Would you mind doing a comparison between the mx500 and the pk3?

 

[parrot5]

Quote:

Originally Posted by penguindude /img/forum/go_quote.gif I always felt the mx51 extremely lacked bass.

Notice that I didn't compare them with my other earphones. This review is just a head-to-head comparison between just the MX500 and MX51. And there should be no question that the MX51 has LOTS more bass than the MX500, amped or unamped. (Unless you mod the MX51 and tape the hole on the back of the MX51, or if you just tested the earbuds for a short time so you used your finger to press the earphones against your ears, and covered the hole with your finger. This would TOTALLY eliminate the bass.)

Quote:

Originally Posted by swissporky /img/forum/go_quote.gif parrot5, Have you been able to hear the Yuin Pk3 yet? Would you mind doing a comparison between the mx500 and the pk3?

I would love to have an opportunity to test the Yuin line, but unfortunately I don't have any of them. I am always on the look out for earphones better than the MX500, though, and I definitely will consider the Yuins next time I buy earhpones since they have been getting quite a lot of hype around here. Thanks for the suggestion.