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M-Fidelity SA-12 Canal Sized Dual Driver Custom In-Ear Monitor Review

M-Fidelity (formerly Starkey) is located in Norway and makes a full range of custom IEMs from single drivers through their flagship 4 driver SA-43.  Back before the switch to M-Fidelity, I contacted Alf Starkey Norway to inquire about the difference between the various Starkey/Tunz companies.  Alf was extremely helpful and friendly and offered to send me a sample of the SA-43 for review.  After I sent my impressions for the SA-43 he asked if I also wanted to try the canal only version of the SA-12.  Price of the SA-12 is around $600 plus VAT.  

Alf from Starkey Norway left Starkey and started M-Fidelity, bringing his product lineup he used to have at Starkey Norway.




The SA-12 uses a TWFK (single-case dual balanced armature driver) in a 2-way configuration with a crossover at 3K placed as far as possible from the ear drum.  There is a single sound tube in the acrylic shell that is filled with silicone in the canal only sized shell, although it is offered in full-ear size also.  What this means is that this is not a full custom, but just the part that fits into your canal.  The cable is not detachable with the canal size option and available either cable over-the-ear or cable down designs.  I chose over-the-ear due to my preferences.  Starkey uses filters in the end of the nozzles to prevent debris from clogging the sound tube/getting to the driver.  The filters used can actually be cleaned with the included cleaning tool and I haven’t needed to chagne the filters since getting the SA-12.  The specs are as follows:

* frequency response: 40-18,000 Hz
* Sensitivity: 113 dB/mW
* Impedance: 32 ohms



The SA-43 comes with an impressive amount of accessories including: Large zipper case (that holds everything, about the size of a double CD case); small zipper case for the IEMs; 8 replacement filters and replacement tools; cleaning tool; instruction manual; shirt clip; alcohol wipes; ¼” to 1/8” adapter.  While the accessory kit is impressive, I prefer other accessory kits such as the Minerva kit.  The case isn’t the deepest although it does hold the SA-12 fine and seems adequate but not great.  Also the shirt clip is a little large for my liking.


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Cables, especially permanent ones on expensive headphones, are very important.  The cable is a twisted cable, silver in color typical of custom IEMs.  It is very flexible and tangle resistant and with the over-the-ear design I get no microphonics.  But, being the silver type cable, it is turning green with oxidation.  The exit point of the housing is enclosed in a tube.


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The shell is free from defects and seems to have a rock solid design with the silicone fill.  The cable exit point is reinforced with a tube around the cable exit point.  However, I would have liked a little longer tube as it is difficult for me to pull the housing out of my ear without pulling on the cable due to the short tube length and canal only design.  While Starkey said they don’t have issues with this and cables typically last 2-3 years with regular use, they can make the tube longer.  It might be the size of my ear canal as Alf said he can move the shell to the side and then remove the shell.


Over time it became more natural for me to remove the SA-12 by pulling on the small cable strain relief since the suggestions Alf gave me for removal didn’t work well.  Also, through my review time I did use the tip cleaner to clean debris out of the interchangeable wax filters, but didn’t need to change the actual filters.  I did just to see if I could tell any sonic difference and I couldn’t.



The canal only design decreases isolation compared with the SA-43 and puts it somewhere between an acrylic shelled custom IEM and a silicone shelled acrylic custom IEM.  The SA-12 isolates much better than the half shell Fabs, which is a hollow acrylic shell that isn’t inserted as deeply as the SA-12.



The SA-12 received 100+ hours of burn in as is customary before I do my serious listening.  You can read about my technique here.  My expectations were mixed, low in part due to the single TWFK used and high due to the price.  I compared the SA-12 with other custom IEMs in the price range including the Kozee Infinity X3, Fabs Fabulous Earphones, Thousand Sound TS842, and Minerva Mi-3 as well as the Audio Technica CK10 and Earsonics SM3.


Bass: The bass is warm and has decent weight considering the driver used.  The sound is thicker than I would have expected with great texturing and detail.  Per the specs the bass goes down to 40 Hz, but to my ears the bass started to roll off at 30 Hz listening to test tones.  There is some decent deep bass rumble, and while not as much as the Infinity X3 or TS842, there was more than the Fabs and Mi-3.  Overall quantity is fairly balanced with the rest of the spectrum on par with the more neutral custom IEMs I have in the price range for comparison.  The detail levels are about the same as others in the price range, however when texturing from note sustainment is in a track, the SA-12 performs on the lower end of the competition.


Deep bass notes and bass with boom sounds authoritative but bass notes that don’t reach quite as low lack the same amount of reverb.   Some examples of nice reverb and articulation include Pendulum – Slam, Flow Rida/T Pain – Low, and Chris Jones – Long After You’re Gone while some examples of the bass having less articulation than I am used to/expect include The Eagles – Hotel California, Eminem – We All Die One Day, and Hans Zimmer – Dream Within A Dream while some are on the fence such as One Republic – Apologize, Blondie – Heart of Glass, and Massive Attack – Splitting the Atom.  What I found in common was natural drums that don’t hit too deep don’t have the texture I am used to hearing while deep bass usually has good reverb and isn’t too far off what I expect.


With the Anedio D1 as my source the SA-12 bass performance increased dramatically and with colder sources such as the HUD-MX1 with OPA1611 op amp the bass performance was weak due to lack of note thickness.


Mids: The midrange is analytical with a touch of liquidity and average detail levels for the price range.  With a boost in the upper midrange, the treble seems a little thinner than the bass region, although there is very good match and flow between the bass and midrange.  This boost give the mids a little bump forward, however the overall presentation of the mids is more neutral than mid-forward.


Treble: The treble extends to 16K before it gently rolled off in my test tone listening which resulted in 17.5K as the last audible tone, maybe somewhere around 6+ dB down.  The treble quality is on par with the competition and is never offensive nor sibilant with a slightly analytical presentation.  There is a slight treble bias to the overall presentation, but the treble is integrated with the mids.


Detail levels of the treble are on the lower end of the competition as the micro-detail is not recreated such as the fine reverb of a cymbal or the lower amplitude harmonics of many instruments.  For example, the ultra smooth Mi-3 has a slight amount more detail but with more sustained notes while the TS842 will recreate the micro-detail and fine harmonics, although with more of an edge and a peak.


Presentation: The overall presentation is on the analytical side with a touch of warmth while not being overly bright resulting in a very balanced earphone.  When I was A/Bing with other IEMs I kept thinking that the SA-12 had a more neutral balance than everything other than the Fabs, which were close in how neutral they were, but the Fabs are on the colder side through the bass region but have a thicker mid/treble note.  Dynamic range is average as is the speed.  overall detail levels are not quite up to par with many of the customs in the price range as the details are there for the most part (depending on the source), but are at a greatly reduced level compared with the majority of the music.


For a custom IEM, the presentation is a little on the intimate side and not the most 3D, but it does nothing wrong.  One of the strengths is it takes an analytical presentation, adds some hints of smoothness and warmth to go with better than expected deep bass response that pretty much eliminate the issues I have had with other analytical presentations such as too much treble and sibilance.  The SA-12 is forgiving for having an analytical sound signature.


While having a slight tilt toward the treble region, the balance across the frequency spectrum is actually very good and better than what I have heard from other TWFK IEMs, although they all cost less and are universals.  No part of the spectrum dominates another and there is no particular focus.  The mids are in line with both the bass and treble from a presentation standpoint resulting in a natural presentation.  If the vocals in the track are forward, that is how they will be presented, if drums are behind other instruments they will be placed appropriately.


Comparison with the Minerva Mi-3:  Mi-3 sounds flatter, with more of a mid-focus.  The Mi-3 sounds a bit more spacious than the SA-12 and has more forward projection, putting you further from the performers, but the SA-12 images better.  Transparency and clarity go to the SA-12, but the differences aren’t large, and the coherence across the frequency spectrum is also better.  The average note across the spectrum is thicker with the Mi-3, leading to a richer yet slower sound.


Bass quantity and impact go to the SA-12 as the Mi-3 just sounds bass light.  The midrange of the SA-12 is more intimate, but also displays a bit more detail than the Mi-3. Treble of the Mi-3 is a good deal more laid back, but is smoother and more liquid with a very nice note decay, giving instruments great reverb.


Both are similarly priced and aren’t the easiest to drive, but beyond that, they fit different preferences.  The SA-12 has more bass presence and bass warmth to go with additional brightness presented with a smaller, more intimate presentation that has slightly better imaging available in a canal sized shell.  The silicone shelled Mi-3, in contrast, has a very rich and liquid presentation, especially throughout the midrange, projects further from the performance, but in turn has a much more laid back sound.


Comparison with the Fabs: The Fabs have the closest sound signature to the SA-12 and are about the same price.  Also, they are smaller shells with permanent cables, so there are many similarities.  The Fabs are easier to put in and especially take out but the SA-12 isolates quite a bit better.  Both use ear wax filters at the tip of the sound tube, however the Starkey filters are better than the Fabs filters in use.  I am able to clean the Starkey filters with a cleaning tool, as they are wider and deeper while I have trouble cleaning the Fabs filters, and they clog much easier/quicker.


Sonically, while similar there are differences.  The bass of the SA-12 is warmer than that of the Fabs with more note sustainment and kick, although the Fabs accentuate the very deep bass more than the SA-12 and can output more deep bass qualtity.  The midrange of both are forward, but the forward area is at a lower frequency with the Fabs than the SA-12.  Treble of the Fabs is smoother than that of the SA-12 with less emphasis and a little less extension.  The Fabs sound airier and dryer yet with more intimate vocals than the SA-12 which has a slightly narrower yet more 3D soundstage.  Overall the SA-12 has a more coherent presentation with better blending between the frequency spectrum while the Fabs are more detailed and overall smoother yet drier.


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Comparison with CK10:  The CK10 is a good all around performer that has withstood the test of time for those that like its more analytical presentation.  Prices range from $200 to around $300 depending on the availability and sales.  The SA-12 is over double the price at $600, however if Tunz in the US and/or UK decide to pick it up the pricing should be much lower according to Starkey as labor costs in Norway are very high.


Putting the CK10 in my ears with the triple flanges that I used to tolerate due to those tips offering the best sound quality is now irritating since my ears have become accustom to the perfect fit of my custom IEMs.  I also did some listening with the HiFiMan large bi-flange tips.  Comfort of the SA-12 is miles ahead for me.  Isolation of the SA-12 is also better due to the silicone fill in the acrylic shell.


There are some similarities between these two, but given time to compare them and use of different sources I did find some significant differences.  From a sound signature standpoint the SA-12 has a slightly wider soundstage with a bigger headstage to go with a further listening position.  There is more note decay across the entire spectrum and more warmth to the sound as well as a slightly slower front edge with the SA-12, but not by much.  While there is a little upper mid bump with the SA-12, it is not to the extent of the CK10.  Treble is also different as the CK10 has more emphasis in the upper mids/lower treble region allowing the CK10 to slice through any thickness and add excellent clarity.  Extension is about the same in the treble region but the SA-12, while having more bass weight, does roll off vs. the CK-10 extending out to 20Hz.  The overall presentation of the SA-12 is a warmer, thicker, richer presentation that sounds balanced in comparison while the CK10 sounds on the brighter side.


Detail levels of the two are similar as neither is the most detailed, lacking articulation of the quieter, finer nuances in much of my music, but the SA-12 does slightly edge the CK10.  Imaging of the CK10 is an area where it shines and beats the SA-12 and the transparency level is also slightly higher, however this seems more of a result of the presentation combined with the bump in the upper mids/treble region and note speed.


The different in spaciousness, clarity, and note sustainment between the two differ with the source.  For example, the HUD with the OPA1611 op amp is neutral in frequency response but on the faster/colder side and actually somehow pairs better with the CK10 than the SA-12.  With the iPod->Pico Slim the warmer SA-12 with the thicker note sounds more realistic to me, making the CK10 sound a little too thin.  Same with the 801 even though it is a warm source, the clarity of the CK10 isn’t all that much better but the warmth just sounds lacking.


Overall how large of a difference is there?  Technically there isn’t that big of a difference, but they both have different strengths due to sound signature differences.  The CK10 has clarity that cuts through a performance like a knife and gives you a more intimate performance with fantastic imaging and great transparency.  Other than these strengths, the SA-12 outperforms the CK10 not to mention offering an overall more complete and well rounded performance  with a richer and more balanced sound, the SA-12 has the advantage not to mention the advantage in isolation and comfort.


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Gym Use: I took the SA-12 to the gym one day, replacing my SM3.  While not as bass heavy as the SM3, nor as thick, the SA-12 still provided enough bass kick to get me going to go with the great comfort I am used to with added clarity.  Isolation was fine, but in the gym I don’t need all that much and use outside was free from wind noise.  When I removed the SA-12 to talk to someone it was easier to put in than the SM3 and isn’t the big monstrosity in my ear that a full custom IEM is.  I have tried the Fabs at the gym but wasn’t happy with the bass response.  And while I have concerns about hollow shell custom IEMs in the gym, the SA-12 is much more solidly built and worry free.


Volume performance: The SA-12 has very good low volume performance to go along with an average sensitivity.  Even when the volume is very low bass performance doesn’t change much, outperforming many other IEMs with multiple BA drivers.  At loud volumes (louder than I am comfortable with for any extended period of time) the bass reverberation increases with an added thickness to the notes, even with some of the tracks I thought were poor performers in the bass section above.  But I don’t recommend listening at loud volumes to protect your hearing.


Sound Summary: The SA-12 provides a presentation that is slightly on the bright and analytical side but has more note thickness and warmth than would be expected with the presentation.  Bass weight is good and bass heavy music comes through with decent weight most of the time and treble, while on the analytical side, has a softer edge and good quality.  Mids have a slight richness to them with a slight mid-forward presentation that is centered in the upper midrange region.  While not the most technically proficient in at the price range, the SA-12 is forgiving of poorly recorded source tracks with most sources and offers a smoothness to go along with the an analytical performance in line with the price point.  With the very cohesive presentation across the spectrum, I found myself coming back to the SA-12 even when I wasn’t listening for review purposes as I do like the combination of presentation characteristics quite a bit.



Source matching

Portable Sources

Clip+: Compared with the 3G and RoCoo the Clip+ sounds a little small and the upper mids are enhanced, which when combined with the lower levels makes the SA-12 sound off.  However, I do use the Clip (regular version, not Rockboxed) when I go to the gym and have no issues with the sound.

iPhone 3G: *** great match *** Nice match with good space and an overall balanced presentation that was enjoyable for extended periods of time.  This combination is musical with its spacious and airy presentation, although detail is lost compared with higher end sources.

Blackberry Bold: The SA-12 isn’t all that difficult to drive, therefore the Blackberry Bold does an adequate job.  Detail levels are in the same ballpark with the Clip+/iPhone, but the overall sound is closer to the Clip+ with a little less bass.  Treble can be a little on the harsh side in comparison.

RoCoo: With a presentation that is a little on the bright/thin side, the RoCoo is an OK match for those that want an analytical and thinner sound.  Details don’t come through like with some other IEMs, but coming from the iPhone 3G I long for additional warmth and spaciousness of that source.

AMP3 Pro2: As is usual for the AMP3 with custom IEMs, there is hiss detracting from the otherwise outstanding performance given the size/simplicity of this DAP.  The presentation is very 3D with instrument placement and a little above average spaciousness, however the bass performance isn’t great as there is impact but not much reverberation. 5/10

801: *** great match *** More detail than any of the sources listed above with very good 3D presentation but less forgiving when the source isn’t quite perfect.  The 801 lacks the air of the 3G, both other than that it surpasses all sources above.  Bass presentation is quite good with power and depth


Modded iPod 5.5g ->

Arrow 12 HE: The Arrow balances out the overall tone from the slight treble balance to very balanced.  Deep bass isn’t great and the rumble isn’t quite as good as with other amps/sources not to mention instrument separation isn’t quite on par with the other amps. I wonder if the output resistors are interfering with the crossover in the SA-12.

Pico Slim: A step up from the Arrow 12 HE, the Pico Slim has bass authority and keeps the instrument separation as it should be, but it does shift the tonal focus a little more to the brighter and leaner side.

Stepdance: *** great match *** Combining the best aspects of the Pico Slim and the Arrow 12 HE, the Stepdance gives bass kick, warmth, and a nice overall tonal balance.  Too bad the Stepdance isn’t the size or form factor of the Pico Slim or Arrow.


Desktop Sources

Toshiba Satellite Laptop L555D-s7005 (Realtech High Definition Audio): Decent at best with rough treble and a congested presentation in comparison with the portable sources such as the Clip+.  Bass levels are good and the soundstage is actually about the same as the RoCoo (better than the Clip+).  Detail levels are similar to the lower level DAPs.  If you have nothing else to listen to, you can probably get by with this as a source.

HUD-MX1: With the OPA1611 op amp the HUD is very neutral and the SA-12 (and CK10) sound pretty thin.  Bass just isn’t very impactful or powerful but clarity is stepped up a notch.  The CK10 is actually a better match than the SA-12 with this configuration due to increased clarity while not losing too much bass.

->Stepdance: ** good match ** Much better overall reproduction than the headphone out due to increased note thickness.  Detail levels are close to that of the 801 with a more forgiving presentation as the overall presentation is a little more liquid, although the soundstage isn’t quite as 3D with about the same width.  While bass levels are improved, they still aren’t quite as good as when the Stepdance is paired with the modded iPod 5.5g.


Anedio D1 (Musiland Monitor 01 USD transport): **** amazing match **** People probably are not going to use this source with a $600 custom IEM, but if they do the D1 will take the SA-12 to another level.  The sound is much richer and fuller and everything just gets better.  The bass was deeper with more punch, the treble smoother, and the SA-12 became much more transparent.  Amazing! 10/10


Source Summary: The SA-12 is fairly source dependent ranging from anemic with a leaner, neutral source to surprisingly rich, balanced, and transparent with the excellent Anedio D1 source.  The iPhone 3G sounds very good with the SA-12, but isn’t going to exhibit the resolution of better sources, and as you go up the source chain, the SA-12 becomes thicker, more liquid, and overall more musical with slight improvements in detail along the way.



One of the few small form factor custom IEMs on the market, the SA-12 has a lot to offer including a sound I wasn’t expecting from the TWFK driver.  The accessory pack is thorough although not perfect, but better than average.  Build quality is great and isolation isn’t bad for a canal only custom IEM.  On the sound front the SA-12 has an overall lean toward an analytical and bright presentation but the thickness of the note and warmth give the SA-12 a richness not usually found with the other characteristics, not to mention acceptable bass rumble.  The SA-12 can’t quite keep up with the detail or extension of the competition in the price range, but I can see many people enjoying the overall combo of the rich yet analytical and close to neutral presentation.



Small form factor is nice and silicone fill increases isolation

Overall presentation is very enjoyable and a great combination of traits



Price tag is high for the technical performance

Cable strain relief is a little too short for my liking making it difficult to remove without pulling the permanent cable





Having a life-long love of high-quality audio and gadgets, average_joe got back in touch with his audiophile side after a hiatus caused by life. His focus became headphones and related gear as the size and price fit his life better than home audio. He believes the entire audio chain is important, and likes to continue to think past the headphone and on into the head, as he believes understanding the details of how we hear will lead to a better audio experience.


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