Yinyoo D2B4

Disclaimer:   I purchased the Yinyoo D2b4 at a reduced price from Wooeasy headphone Store’s Ali shop.   If you have an interest in purchasing the D2B4, it can be found here.


Unboxing / Packaging:

The D2B4 arrived in the now familiar blue box with the Yinyoo logo in gold.  This is the same box used for most of the higher-end Yinyoo models and stores the earpieces in a foam tray in the upper section and all the accessories inside the soft-case below the earpieces.   Details regarding model # etc are printed on a sticker on the outside of the shrinkwrap, so once removed, there is no indication which model this package was meant to hold.  So far in comparing with a couple other models, there is a difference in the foam cutouts for the earpieces so having the boxes labeled in some way would be advantageous.



The D2B4 ships with 6 sets of tips, three in black silicone, and three in spin-fit style tips, a soft carrying case, and the cable.   This is a pretty standard kit and my only complaint would be that with the size and bulk of the cable, the soft-case is rather on the small side.


Build is quite good with the shell being made of 3 parts, the Face-plate, inner shell, and nozzle in a semi-teardrop shape.  All are well polished and color matched so it looks like a 2 part shell unless you really look for the seam at the nozzles.   All edges are polished smooth with a high gloss finish coating the entire surface save a ring of uncolored metal around the perimeter of the faceplate.    MMCX connectors are tight and exit the top rear of the shell lending the D2B4 to tip up only wear.   Nozzles exit the upper front edge of the shell with a very mild forward rake.  A prominent lip helps hold tips on, and a chrome plated grill helps keep particles out.   Two vents are present on the inside of the shell and are marked with red arrows in one of the photos below.  The Yinyoo name and L/R designations are printed on the rear of the shell.   I found the D2B4 to sit well in the ear and not be prone to move unless really strenuous exercise or more likely a good tug on the cable.



Little surprise here, the model name gives away the internals,  D2 B4 stands for Dynamics x2 and Balanced Armature x4 per side.  Each side houses a 10mm graphene coated dual-diaphragm dynamic driver (this accounts for the D2), a pair of midrange drivers (most likely Bellsing 50060s but not documented), and a pair of High frequency balanced armature drivers (again most likely Bellsing 50060 drivers, but not documented).    Nominal Impedance is listed as 19Ω with a  sensitivity of 102 dB/mW.  This makes the D2B4 easy to drive and appropriate for use with cell phones or tablets as source.  I did find the D2b4 benefited some from a more potent source, but it was listenable directly from my Android and iPhone.



The provided cable is a heavy 4 core silver plated copper cable that starts with a straight 3.5mm jack with a black rubber encasement.  The cable exits the jack as a twisted pair with grey sheathing and runs to the splitter which is a barrel shape in matching black and also sports the Yinyoo name.  Two single strands exit the splitter and then terminate in pre-formed earhooks without memory wire and mmcx connectors.   Right is clearly marked with a red ring, and a chin slider bead is provided as well.  Overall, the cable is solid, but it does lack strain reliefs at all the joints.  As heavy as it is, this may not be a concern.





Sub-bass is present in good quantity and provides good rumble when called upon.  Sub-bass is somewhat monochrome as it lacks a bit of texture and can be a bit looser than I would prefer. Mid-bass is pushed forward and has more detail than the sub-bass but sometimes suffers a bit as it can get a bit aggressive and when it does, it tends to get loose and thicker than it should be.   By the time mid-bass transitions into the lower mids, it has dropped back significantly from its peak but there is still perceptible bleed into the lower mids.  To me, the bass is the weakest part of the D2B4.



Fairly prominent mid-bass bleed into the mids adds warmth to an already warm sound but detracts from overall detail and is particularly notable in lower male vocals.   As you move through the mids toward the treble the mid-bass bleed gives way and mids are increasingly pushed forward.  This gives female vocals a cleaner sound, but pushes them significantly forward of their male counter parts.   Upper-mids plateau at roughly the same point as the mid-bass to create a V shape with the dip in the lower mids.   Strings are nicely reproduced as is acoustic guitar with electric guitar sounding good, but not quite as realistic as its acoustic counterpart.   Here I would say the D2b4 is more W than V shaped as vocals are definitely forward and mids don’t sound recessed although technically speaking, they are somewhat behind the mid-bass and treble.



Lower treble is prominent and follows the upper mids.  True treble begins rolling-off fairly early (between 5 and 6kHz but is a more gradual drop than typical which leaves the D2b4 with more air at the top than expected if one is looking at the FR charts.   To me, the treble reminds me a bit of the Mee Planamic in that at times it has more sparkle than expected, while at others it can feel a bit enclosed.   I think whether you love or hate the treble on the D2b4 may be entirely decided by your listening habits and source material as some tracks sounded really open with good air and sparkle while others sounded dark and enclosed.   I haven’t figured out the pattern, but suspect there is something there that could be used to determine what tracks the D2b4 is likely to dislike as they tend to share some of the same characteristics.  (For me the tracks most likely to feel dark were more folk and folk rock oriented tracks).


Soundstage / Imaging:

The D2B4 definitely has more stage width than depth, to my ear by a ratio of almost 2:1.  The stage does have some height and movement around the stage is well represented.  Instrument separation is good once you get past the mid-bass sloppiness, with higher pitched instruments doing particularly well.  In fairness, at times the seperation of the lower voiced instruments is equally good, while at other times it suffers a bit.   Imaging is also dependent on the same phenomena and is at times better than others.


Ok so it sounds like this earphone has some potential, but also some failings.  Luckily, a happy accident may provide the answer to some of those failings.  While putting new tips on to try and see if tip rolling helped, I found that one nozzle seemed loose.  With a little more fiddling, I found that the nozzles unscrewed to reveal the sound bores.  Ok so maybe I could adjust by adding a filter to the sound bores was my first thought.  My Second thought was, “I wonder what the chances are that the DMG/M6 or LZ-A6 filters will fit?”   Well guess what, all of those filters do fit.  So we have 3 filters from the M6 to try, the Vented DMG Filter, and 6 filters from the LZ kit we can try out.   Some astute person just said “6, I thought there were 9 in the LZ kit”.   Again, correct, but with the sound bores protruding into the base of the filter from the D2B4, the dark blue, violet, and silver filters with their narrower bores obstruct one of the sound bores so they cannot be used. (See Below).

M6/DMG Filters:

The filters from the M6/DMG that are most likely to have a positive impact are the Silver (enhanced high frequencies) and the Vented (reduce bass, improve mid-high frequency) so I tried each of those.   Of those two, by far and away the biggest improvement to my ear was the vented.

Sound notes using the Vented Filter.


Bass and sub-bass are dialed back significantly  by using the vented filter and a lot of the slop noted in the stock version is cleaned up.  It still isn’t crystal clear in the lows, but is dramatically improved and separation of instruments in the lower ranges is vastly improved as well.   Those who want the most possible bass thump wont appreciate this change as it does bring the sub-bass down and the mid-bass more inline with the rest of the signature.  For those that find the bass a bit much on the stock version, the $5 for the vented filter is a good spend.


Mids seem to be changed the least by the vented filter but the removal of some of the mid-bass bleed improves lower mids and male vocals.


Treble energy is improved slightly by the swap in filters and gives the D2b4 a sound signature that is brighter than stock, but cleaner with a bit more air.


LZ-A6 Filters:

The Filters from the A6 set that seemed most likely to be helpful are the Blue, Gold, Gray, and Magenta.  Blue and gold are nearly identical to the default until you get above 1kHz so they do nothing to tame the bass.   Gray does some to tame the bass, but brings the treble down more than I would like, and magenta brings everything down but does so more proportionately.   To my ear, the Magenta would be my 2nd choice behind the BGVP DMG Vented filter.   This is somewhat fortiuitous as the Vented filter is the only one sold individually so allows users wishing to try it the chance to do so without having to purchase an entire set.



Yinyoo Topaz

Build quality  – a dead heat as both are very well made metal shells, but both fall short on the cable at their price points.

Sound quality – without using the vented filter, I prefer the bass on the Topaz as it is a good bit cleaner and doesn’t intrude on the mids.    With the vented filter, the D2B4 takes a big step forward and outclasses the Topaz in sound-stage, separation, and mid/treble presentation while bass is at least equally good if not a little better.


NiceHCK M6

Build quality – again – no clear winner. both good shells, both tunable filters (same ones at that) and both have less than spectacular cables.

Sound quality – Without the vented filter, the M6 is a good bit cleaner and more detailed.  With the filter change, I still prefer the M6 Mids, but not by nearly as much and most other facets of sound quality are now in the D2b4’s win column.  Stereo separation is wider on the D2b4, while the M6 feels much narrower,  Sound-stage is larger on the D2b4 both in depth and width and dare I say even holographic on some tracks.   Mids are cleaned up substantially but still not quite as detailed as the M6.  Bass is more inline and neutral which is a + for the D2b4 for me, but the boosted bass of the M6 may be a + to others.

Overall this comes down to preference if the vented BGVP filter is in play.  Without the add-on filter neither is as good, but the D2b4 suffers more than the M6 and is a less listenable signature.


Thoughts / Conclusion:

If you ever had any doubts that filters work, this is a perfect test bed to prove they do.  A happy accident saved the D2B4 from being relegated to the also-ran pile.   If I hadn’t discovered the nozzles could be removed and the filters from other iems fit, this would be a very different conclusion.  As it stands, I really like the slightly modified version of the D2b4 and feel that if Yinyoo has the option, they should include a filter of similar design with the next generation of the D2b4.   With the mods, the D2b4 has one of the best stereo sound fields of any IEM I have used recently, with good detail, and a comfortable fit and signature.    For those that have already relegated the D2b4 to the scrap heap, pull them back out and pick up a filter, you’ll be pleasantly surprised.  (Filters are available here).