Sonny – ACS is one of the original custom in-ear monitor makers and the the one I can confidently say is leading the way here in the UK. This our third article on all things ACS and in our first we visited their lab and had a look at what an amazing operation they have going on, for some context about the brand and a guaranteed respect for the company, I would head over and check that out now!

Today though we are looking at their reinvention as a brand and their first big activity in the consumer scene for quite some time. Scrapping the old models they had in the T1/2/3 and releasing a new single driver in the Evoke, a reworking of their old flagship 3 driver in the Evolve and finally the Encore, a brand new top of the line model featuring 5 drivers.  Of the lower two models they have offered even better value in snazzy looking universal models and all of the CIEMs are available in both a studio option and a Live! configuration for stage use with a built in microphone etc.

The Monitor

We have the new 5 driver, which is also the most expensive  of the range at £749. Not unusual to ACS but not as common in the worldwide CIEM scene, ACS opt to use silicone, which they 3D print and while they do not have near as exotic options in design as Polish Custom Art, they have a nice colour selection, an option of artwork and the finish is clean and professional. I went for a clear shell while Josh went for a glittery grey, both are smooth with no imperfections and to finish it off perfectly we have the Inearspace “E” nice and bold on the “faceplate” of the monitor. That brings me onto my next point and that is how these don’t really have a faceplate like most other monitors, instead these are just a blob of silicone made at one time. It doesn’t cause any problems but does leave the fitting rather uniquely and it completely threw me at first. Instead of the normal rotatation to get the canal in, you have to tuck the top of the earphone under the antihelix and then push the canal portion of the Encore in. It is a little bit fiddly, especially if you’re used to an acrylic CIEM but it becomes second nature (taking them out is always a pain) and it feels really snug and gives amazing isolation. The isolation of these is unparalleled probably due to a combination of material and way of fit. Something I also want to mention is how mine were made completely digitally, with the impressions being sent over from Ultimate Ears who scanned my physical impressions in. Josh’s digital impressions from UE managed to get lost somehow?! We dont understand how that can happen either!!

While silicone monitors sometimes leave me feeling a bit unsteady due to their soft and malleable shells, these feel thicker and stronger than both my original ACS T2 and Custom Art Harmony 8 Pro. Josh thinks they feel sturdier than his silicone Minerva Mi-Performer Pro’s too. The cable choice to me is interesting, originally I was very excited but after using I am less sure. They include the Linum BaX cable, which has seen great excitement in the community due to its unrealistic slender build and great strength. People that wear glasses are amazed by how it doesn’t get in their way and on the surface there is a lot of love. For me though it has just been a pain, I think I have spent more time untangling it than I have listening to these earphones, they are like the memes you used to get for Apple Earbuds, put them in their case and on removal they have tangled into 1000s of knots. That being said the cable is super thin and does have its perks such as ergonomics when wearing and the feeling of nothingness as if the cable doesn’t exist and overall I don’t think it was a bad choice. I just think Linum can get that tangle issue under control but that is hardly ACS’s problem. That being said I know Josh has had a more frustrating time with the cable than me, I wil let him take over.

Josh – ACS have actually decided on a new connector that is known as the ‘T2’, it is claimed to be super reliable and very easy to remove and plug in however… my sample has been somewhat intermittent on the left channel and I have only swapped cables once. So if you are looking at my measurements a couple of images below and wondering why there is only one channel, thats because this channel is very sensitive to movement on the cable connection. Any tug or nudge and it cuts out. Quite disapointing really but once they are in my ear and I’ve adjusted the cable a bit they do behave themselves. I know if I was a customer ACS would have no problem repairing them, but as I’m sure you can understand, they arent my ‘go to’ custom so I haven’t bothered getting them fixed.

My biggest annoyance in this area is the fact that we do not need another cable connection, the more common 2 pin connection is great and I have never had a problem with it, so any other companies reading this, WE DON’T NEED ANY MORE CONNECTIONS, please.

Sonny – As for the overall package, I didn’t receive it but I do know it comes with the wonderful Revivo that Josh reviewed here so along with the Linum and Revivo, you are getting some expensive stuff bundled!

The Sound

My first impressions of these and one that has continued through this day is that these are a bassy earphone. Initially this was fairly surprising as I had heard the Evoke and Evolve at ACS’s labs and both had great balance but this has a clear focus on mid bass but continues with some solid extension down low. That being said the midrange doesn’t feel lost, the lower mids are fresh but the upper mids are where we find the sound to begin to become a little recessed and lacking, there isn’t any bite or excitement in female vocals, these earphones seemingly lack clarity because of it too. The treble also seems a bit curtained by the plump bass, only showing a bit of sparkle at around 10kHz. That being said it is not the level of boosting in the bass that makes it such a dominating frequency range but the fact it is thick and a little on the slow side. On top of that it seems a little backward projected in the sound stage. That being said it is combined with strong extension and it is powerful which gives a rather nice lingering impact.

Josh – As you will see on a couple of images down, my sample don’t have the same peak at around 10k, and my Encore does sound very rolled off in the treble, far too much for my liking. They sound too soft with a distinct lack of cleanliness and definition throughout actually, not just in the treble. That consistency does mean they do sound quite coherent though, no part seems to stick out as sounding ‘wrong’ for the rest of the earphone, they are squidgy and vague throughout.

I wouldnt call the soundstage small, it’s just a little muddled and again lacks the edges and definition it needs to be a quality sounding earphone. The texture on anything thick or more complex suffers dramatically because of this, it’s genuinely just a blob of bass and other sounds becasue the bass seems to linger for days and I’m sorry but its just not up to scratch at £750.

On a more positive note, if you listen to pop R&B and Hip-Hop these are quite fun sounding due to the big bottom end, you find yourself cranking them pretty loud and getting right into a bit of EDM or Hip-Hop. They give that energy and a little bit of dynamism that saves them a touch and they are enjoyable on certain genres, honestly.

Another positive to some extent is that they aren’t very transparent, at all, so you can quite happily use your phone as a source if you just need to plug something in quickly to walk to the shops for example, you wont notice as big a difference as with something like the UERM which sounds terrible if not fed right.

The Measurements

Sonny – So lets take a peek at the frequency response graph.

The most impressive thing for me here is the channel matching, which until 3.5kHz is spot on. 3.5kHz certainly looks like a crossover because of the channels not only show slight seperation but we also get notch in the frequency response which I think we would be better off without, probably lending a hand in the not so involved upper mids and female vocals we heard.The treble is playing well with the mids though and has a nice presence around 9kHz.  While channel matching is good I also measured Josh’s Encore to see unit variation.


Once again until the peak we seem pretty much spot on to my unit but after wards the treble does seem a little different, the 5.5kHz peak remains but instead of a 9 kHz peak we have a smaller one at 11kHz. It isn’t the biggest difference but that will apply to how we percieve the treble.

Just to show how far ACS have gone with their CIEM perfomence I want to show my ACS T2 measurements.


Yes… Things have come a long old way. Not only have we got no where near as good driver matching we have a horrible suck out at just over 2kHz and it is a rollercoaster ride after that. ACS have clearly tightened up their quality control and improved their sound tuning from the looks of things. Also something I think alwats made the T2 hard to drive was the extremley low impedance of 6.83 ohms, the Evolve is much smarter at 85 ohms making amp matching much easier.

The Conclusion

It is clear that with the new line from ACS things are much better, but at the price range I just feel like these dont have what it takes to be among the very best. They dont have the finesse, speed or coherency to play games with you Hidition Viento-Rs, Heir Audio 10.A and Vision Ears VE6. ACS have built a fun monitor though, one with juicy bass that shakes and will keep you enjoying yourself but it comes with a big price tag that comes with a lot of expectation due to how stacked this price range is. For my fellow Britains though, we do have the perks of no overshore shipping and extremley quick turn around times, ours was like a week, whaaat?! Order an Asian or JH model and you could see half a year go by and nothing to show, I trust ACS a lot more than most and as they are doing a lot of positive things to change the industry. As you know we are building to a big flagship CIEM round up and expect some detailed comparisons to other models in that.

Stay tuned!

Sonny Trigg