ADEL modules.

Stephen’s Ambrose Diaphonic Ear Lens (ADEL) module was a big topic of discussion in my U12/A12 review, and I’m not going to rehash it.  But definitely would like to talk about the effect of default non-adjustable S1 module versus newly introduced B1 module and the fully adjustable MAM module and how they reflect on U6 performance.

Unlike S1 module used in U12/A12 where default signature had a noticeable mid-bass boost, the same module in U6 accounts only for a slight mid-bass boost since this monitor has a more balanced signature.  As a matter of fact while I found the bass in U12 w/S1 to be a bit too much for my personal taste, in U6 the S1 module added a nice punch without being overwhelming.  But at the same time I felt that upper mids were slightly recessed and soundstage had an average width.  Switching to B1 in U6 reduced some mid-bass punch and made an overall sound signature more balanced which also lifted the mids.  Another very noticeable change was an improvement in soundstage, making it wider and more open in comparison to w/S1.  As much as I was enjoying the extra mid-bass boost with S1, the sound with B1 was more to my liking.  You also have to keep in mind that due to S1 dual lens design (vs B1 with a single lens) the isolation will be better with S1, and it also explains the difference in soundstage expansion going to B1 with less isolation.

One might question if they even need MAM adjustable module with availability of S1 and B1.  In reality, S1 sounds like a fully closed MAM module, while B1 sounds like MAM module being close to fully open.  Basically MAM module has a flexibility to fine tune the sound/pressure, including individual non-synchronous adjustment of right/left sides, while S1 and B1 are like fixed presets.  For me personally B1 tuning hits a sweet spot and I’m planning to keep that module in permanently.  Also, having a “fixed” B1 module is great for those who are OCD about MAM continuous tuning since there is no click feedback.

When you switch to manual MAM module and start adjusting it, you hear the effect of a subtle sub-bass roll off and also reduction in mid-bass quantity, but the change in U6 was not as drastic because you don’t have the same low end impact to begin with in comparison to U12.  Also, similar to U12, you can hear the bass being lowered, becoming more balanced as you turn/open the dial and before the ADEL module is fully open the quantity goes back up.  In U6 with MAM fully open, I hear the bass quantity being somewhere in the middle between the highest level (MAM fully closed) and the lowest level (MAM 2/3 open).  It’s not just a reduction of bass quantity, but also the effect where bass is more transparent and I hear it instead of feeling it.

At the current moment 64 Audio is still working on finalizing their ordering form to reflect different modules, so make sure to specify which module (S1 or B1) you prefer in the notes/instructions space when placing the order.  If you don’t specify it, they will send you S1 by default.

S1 vs MAM vs B1.

 

Sound analysis.

Once I put B1 module in and switched to a silver cable, there was no going back for me because U6 scaled up to a fine balanced signature with resolving and detailed natural sound wrapped in a smooth warm tonality.

Starting with a bass, sub-bass extension goes deep with a nicely textured velvety smooth rumble. The quantity is just perfect, not too exaggerated and at the same time with enough presence to give bottom end analog quality, typical of dynamic driver performance.  Mid-bass has a nice punch with a moderate speed, not the fastest attack or the longest decay.  Sub-bass and mid-bass are nicely balanced, linear in quantity, well controlled, and with analog tonality, not typical of BA driver performance.  The bass has a good level of articulation with a natural timbre, but it wasn’t as multi-layered, accurate or highly articulate as I found it in U12.  As I mentioned before, with S1 module you get a little more mid-bass boost while B1 balances it out with a more linear performance.

Mids come alive with a silver cable, becoming more dynamic and layered, rather than being flatter as I hear it with a stock cable.  Lower mids have a smooth warm body which is not too thin or too thick, definitely a little leaner then U12, especially since you have a more balanced bass which doesn’t overwhelm the mids.  Upper mids are organic, smooth, with a good retrieval of details which actually scales up with a cable upgrade.  The mids never get harsh or grainy, they stay very organic and natural, not too smooth where the details are lost and also nowhere near micro-detail level.  It’s a similar phenomenon as I found with U12 drivers, yet they are smoother than a typical BA performance – it sounds smooth analog, but nowhere near the warm and congested dynamic driver performance.

Treble in U6 takes a little backstage due to a warmer tonality with a scaled down quantity.  It’s well defined with a good clarity, but not as extended and with reduced airiness.  You definitely never have to worry about sibilance or harshness, but if you are a fan of a crispy and crunchy upper frequency details you will have to lower your expectations.  The treble details are not muted – just sound more natural and smooth.

The soundstage expansion is very good (switched to B1 module), with above the average width and height, and a slightly above the average depth, creating soundstage which spreads around you while still providing some intimacy.  Also, U6 has a decent layering and separation, but not as much air between the layers.  The sound never gets congested and you have a good separation of instruments and vocals, but it’s not on the same level as holographic imaging of U12 flagship.

Sound comparison.

The question about how U6 stacks up against U12 was the most dominant one after my U12 review, thus I’m going to spend more time going over that comparison.

Both U6 and U12 have a similar warmer tonality, but U6 is definitely more balanced in comparison.  They have a similar sub-bass, but U12 has a stronger and more aggressive mid-bass punch.  U12 also has slightly more body in lower mids and a little brighter upper mids with more sparkle and airiness in treble.  One noticeable difference is higher level of transparency and slightly better dynamics in U12, especially when it comes to mids.  I also found U12 to have better layering and separation with more air between the layers.  And U12 also stands out with a more holographic soundstage expansion while U6 has a good soundstage expansion but not as wide and more intimate.

B1 module really helps U12 in balancing out low end impact and in clearing up lower mids while opening up upper mids and adding a touch more sparkle, but if you are comparing using S1 module, some might prefer U6 over U12 because of a more balanced signature and less aggressive bass.  With introduction of B1 modules, the sound of U6 and U12 scales up and at the same time creates a bigger gap between these two IEMs.  But this comparison takes a whole new turn if you factor in the audio source pair up.  U6 is not as picky and will sound great from any source, even my lo-fi laptop with a noisy built in sound chip.  In contrast, U12 is more picky and shows its superiority when using better sources like my PAW Gold or Opus#1, especially playing high res files.  But paired up with my Note 4 or my mid-fi DAPs or my noisy laptop, the gap between U6 and U12 sound quality shrinks to the point where in some cases I even preferred U6 because it was more forgiving, while U12 lost its shine and sounded a bit muddy.

For some reason I didn’t notice this as much when reviewing U12, but it became more apparent when I reviewed and compared U6.  The bottom line: if you’re building a TOTL portable audio rig or planning to use high res usb DAC/amp (like Mojo or HA-2), it makes sense to invest extra money to go with U12.  But if you are planning to use a variety of different DAPs, or straight from your smartphone or laptop – U6 might be a more versatile alternative.  And of course, if you are on a budget, U6 has an impressive price/performance ratio.

Here is how U6 stacks up against other IEMs/CIEMs.

U6 vs ES60 – ES soundstage is wider and has a little more depth/height.  ES low end extension is very similar, including quantity of sub-bass and mid-bass which sounds similar to U6, but the bass has a little better layering and more articulation.  ES lower mids are leaner while upper mids are a little brighter; where in comparison U6 is smoother and more organic while ES is more revealing down to micro-detail level.  The same with a treble, where ES treble is brighter, crispier, and more airy, and with a better extension.  ES has more transparency and better retrieval of details. Overall, ES is closer in performance to U12, and similarly to U12, ES scales down when driven from lower res sources.  The decision argument between U6 and ES60 is similar to U6 and U12.

U6 vs W60 – both have a very similar soundstage expansion (using U6 w/B1), nearly the same width/height, while W60 has a little more depth.  Very similar sub-bass extension and quantity, but U6 has faster and tighter mid-bass and overall bass is more articulate and better controlled without spilling into lower mids, while W60 mid-bass spill a bit into lower mids. W60 lower mids are thicker, upper mids are warmer and less detailed in comparison, and treble is not as crisp, not as bright, and lacking airiness in comparison.  U6 is brighter, more revealing, more detailed, with more airiness and cleaner mids.

U6 vs UM Maestro – UM staging has the same width and height, but with more depth.  Low end extension is very similar, and you hear a similar quantity and quality of sub-bass and mid-bass, though UM bass is a little tighter.  Lower mids are very similar as well, but upper mids in UM are brighter and a little more revealing, in some brighter tracks even harsher in comparison.  UM treble is also a little brighter and crispier, but not a night’n’day difference.  These two actually have a lot more similarities, where UM sounds closer to U6 than U12, but it still a little more revealing and detailed in comparison to U6.  Also, similar to U6, UM pairs up good with lower res sources.

U6 vs K10UA – K10 staging has a similar width and more depth/height.  Sub-bass is more rolled off and mid-bass has a faster and tighter punch, sounding more BA rather than more relaxed and thicker like U6 which has a more dynamic driver bass performance.  K10 lower mids are a little leaner and upper mids are more detailed, brighter, and a little more upfront. K10’s treble is brighter, crispier, airy, and more extended.  K10 sounds brighter and more detailed and revealing with more transparency, while U6 is warmer and smoother and more organic/analog.  In a way, U12 is kind of in-between of U6 and K10UA, taking the best of both worlds.

U6 vs Savant – Savant staging has a similar width and slightly more depth/height.  Sub-bass has the same quality but slightly less quantity, mid-bass is very similar though a little faster than U6.  Savant lower mids are nearly the same, and upper mids are a little brighter and with a little better retrieval of details. Treble also a little brighter, crispier, and has more airiness, not as rolled off as U6.  Both pair up great with low res sources.  Overall, U6 is smoother and more organic and with a little more analog-like performance in comparison to Savant which is a little brighter and slightly more revealing at the top.

When it comes to pair up with different sources, I already mentioned that U6 is more forgiving and not as picky if you connect it to either lo-fi vs mid-fi vs summit-fi sources.  That doesn’t mean that it will take any low quality source or poorly recorded file and make it shine.  It will reflect the quality of the source, either if it’s warm or neutral or bassier, but I still found U6 to sound good with everything, though hissing level varied.  For example, there was absolutely no hissing with AK120ii, DX80, X5ii, and my Note 4.  But I did hear a little bit of hissing with PAW Gold, N5, L5 Pro, Opus#1, and my ThinkPad laptop.

Conclusion.

I really wish I would have reviewed U6 before U12 because then it would have been in a spotlight without constant comparison to its flagship big brother.  Don’t get me wrong, U6 stands firmly on its feet and proudly carries Stephen’s ADEL technology.  And you can’t discount the most important factor of these multi-driver monitors – the sound quality of 6 fine-tuned BA drivers with a nicely balanced signature and resolving, detailed, natural sound that has a smooth warm tonality.  I personally recommend using B1 module if you want a more balanced sound versus S1 module if you want to enhance your mid-bass.  Also, I’m a big fan of U6 cable upgrade with silver wires which brings more excitement to the sound, especially with a more dynamic and detailed performance of mids.  All together you have one fine tuned multi-driver coherent performance that will sound great from any source and will do right by your ears health!