General Information

At the heart of the T1™ monitor is a driver configuration that delivers an incredible breadth of clarity and depth using a selected combination of drivers. At the top end is a combined unit providing specific drivers for the highs and mids engineered into a single unit with an ultra-compact crossover optimising the response for each, this is then combined with a clear and powerful bass driver to deliver rich and full-bodied bottom end. All of our driver builds are hand-made and individually tested by our technicians in Banbury to ensure that each configuration is a perfect fit for your earpiece.

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Pros: Balanced but musical, excellent isolation, lets good recordings shine, amazing customer service from ACS - still my go-to for 2+hrs a day
Cons: Cost, need tender loving care, isolation worsens conducted noise through your skull, can sound congested, sibilant recordings may become unlistenable
DOI: I don't get to listen to new gear a lot so I may not be any use at answering questions about comparisons to anything other than my own stuff (which may or may not be considered esoteric). I was (and am) a full-size hi-fi person so my tastes in this will clearly colour what I look for in head-fi. I grew up playing instruments and singing in a choir so I tend to value realism of tone for well-recorded voices and instruments but for orchestral works and pop/dance music, I look for neutral-warm musicality and dynamics.
Initial Purchase:
There isn't a lot of choice for customs in the UK though things have improved over the 3 years I've had my T1s. My choice of ACS was mainly down to price and them being English with an excellent return policy. Overseas outfits would carry import and/or shipping-for-refit charges and my top-choice Spiral Ears probably wouldn't have fitted my small ear canals.
Monika Schumacher ( was recommended through Head-Fi and she deserves special mention - an amazing home visit service for taking the moulds and arranging the manufacture with ACS. Most notably, after I'd mentioned pain/fit issues I'd had with custom silicone eartips for my Senn IE8s, she strongly suggested I avoid customs as I might be in for further disappointment. Thankfully, I ignored her

Please bear in mind that the standard cases and accessories for ACS products have changed over time. The T1-equivalent today is the ACS Evolve with slightly different electronics and a Linum Bax cable, though I believe you can request the original version as they now have their compatible Live! ambient processor for sale. They also now do universal versions.
Initial set-up:
Rigid, brown leatherette slide case for storing the 'phones, comfort cream, 1/4" adaptor, wax pick and wax-grid dispenser - too chunky so I used the matching zip-pouch for day-to-day carry.
The T-series cable is long but very strong and not very microphonic. It had a pronounced tendency to auto-coil but tidied up easily.
Fit and isolation:
I took some getting used to these. Fit was great as expected but coming from super-light Senn IE8s and Complys, I am clearly not designed to have things comfortably jammed in my ears. That being said, it got much better over time. The silicone is very flexible and getting them in and out is much easier once the lacquer becomes less sticky. The main issue for me is they need to warm up before they 'disappear' and obviously, YMMV. The excellent seal means that I need to wiggle them around and pop my ears (like when diving) so they sit without 'sucking' on my eardrums - otherwise the bass and soundstage can become lop-sided. The other downside to the isolation is that you notice the noise of blood rushing in your ears and your own footsteps much more readily (and I find this harder to ignore than ambient external noise).
iPhone 4 w/ ALAC initially. The BSG cmoy and my Pimeta v2 amps didn't get much use with the  T1s as they didn't seem to play nicely together. Lately, I've been using an iPhone 5S with the Onkyo player app and an iBasso DX80 with Lurker's firmware (ALAC and Hi-Res FLAC).
A Few Thoughts on the Sound:
Not a bass monster but it's certainly faster than my IE8s and goes a lot lower with enough juice - it does a decent job with my favourite speaker torture track "Why So Serious?" from The Dark Knight OST which goes from screeching strings to barely audible but very palpable bass with a snare drum overlaid. As mentioned in threads passim, voices are a treat with these IEMs: the ladies from Girlyman's live album Somewhere Different Now are wonderfully euphonic in the higher registers, as is the soprano in the 1990 Bernius recording of JD Zelenka's Missa Dei Filii. Patricia Barber's dark contralto is wonderfully husky on Cafe Blue. Instrument tones are generally very good though a bit peaky in the upper frequencies - I certainly wouldn't accuse them of being over-smooth; cymbals are a touch sizzly, the crunchy-sounding guitars on Linkin Park's Hybrid Theory can grate whilst they slam. Processing artefacts like clipping and excessive 'loudness' such as (the entirety of) Florence + The Machine's Ceremonials stick out like a sore thumb and can be rapidly fatiguing.
Now comes the big but: sibilance. I have no idea if this is a quirk of the drivers' frequency response in the 'presence' range or something to do with my set-up but with the wrong recording, it can make me want to chew pennies for some light relief. Good live recordings, unsurprisingly, do better in this regard (compare the studio and bonus UK live tracks of Fun's Aim & Ignite) but even the aforementioned Cafe Blue has this in relative spades (it's certainly evident on my full-size system which is, if anything, rather bright but the distance in space to the listener mitigates this a fair bit) and I suspect is partly due to the miking.
I'd also suggest that these aren't going to replace full-sized phones for large, orchestral works. The soundstage is spacious though not as 'out-there' as my Senns - this is a positive for intimate tracks where the performers are sitting close together, like Somewhere Different Now or Ottmar Liebert & Luna Negra's Up Close (binaural recording!) and doesn't disgrace itself compared to full-sizers. When there are instruments clashing all over the place though, like Messiaen's Turangalîla-Symphonie, it can all sound rather congested, especially at volume.
Care & Service:
These need regular inspection, cleaning and drying to maintain their edge - the tiny, plastic wax-grids that fit down the sound tubes tend to break when removed and aren't cheap bearing in mind you need 4 at a time. Without regularly changing the silica gel or storing these in the airing cupboard, condensation can and will become evident around the components under the silicone and cause one to freak out! However, a careful clean has never failed to restore the sound for me. I have had to return these to ACS 3 times so far - what turned out to be the cable damaged internally at a particularly sharp bend over my right ear and 2 driver replacements (the second out of warranty but at a very reasonable cost of ~5% of what I paid initially + postage). Given that in the early days, these lived in a soft case in the top of my rucksack being bashed around, I'm not surprised. ACS have always been quick to reply, courteous and a joy to deal with. They also warranty their repairs for an extra year.
As mentioned, I've had to return these to ACS a few times and subtle changes have occurred over time: the sound tubes gained little in-line filters and new-design wax-grids. The trapezoidal leatherette case has been replaced by a more practical zipped semi-hard-shell after I lost the little pouch. My second cable failed at the right internal plug-end after just over a year but I was sent a (free!) replacement that was identical in feel but is much less self-coiling. Best of all, I now have a Revivo (included with their new customs) which is a USB-charged drying box with a replaceable silica pod and a UV radical generator to help sterilise the earpieces. It's a lovely idea and slightly more practical than a hearing aid dryer unless you have loads of IEMs.
The T1s have been my everyday listen for 3 years now. For commuting their isolation is fantastic, comfort (once warm) nearly unrivalled and their sound detailed, engaging and musical as long as you can tolerate their unforgiving and revealing nature.


Pros: Comfort, balanced sound, overall quality of both product and accessories, unique purchasing experience, no more leading anyone your earbuds!
Cons: Ultimate cost (though still good vfm), shows poor recordings for what they are.
So Chaps I just wanted to spend some time putting down in words a recent purchase and experience which has been 100% positive, even with the amount of money involved.

First a picture of the little blighters.


Sorry but I nabbed this picture from a review because Susy's out with the camera at the moment. Besides, this is far batter than I would do anyway, but I will and some real ones of mine soon which are all-black in finish with the ACS logo in white on one and blue on the other to ID left from right.

So why have I bought what look like two alien embryos on wires to stick in my ears? Well of late, I've found myself doing an increasing amount of headphone listening in the house, as well as to my main system in the Man Cave. The problem was that my HD580/600s and AKG K701s are open-backed and so my 'personal listening' wasn't that personal and was getting on my better-half's wick.

I started out looking around for a suitable set of closed-back phones, but to be honest, there aren't a lot of particularly good choices apart from something like the Denon AH-D7000s. I was pretty much decided on these when a chance conversation with a friend opened my eyes to an alternative.

Tristan is a classical music freak. He works for Universal Music developing their on-line distribution strategy, conducts and composes for an orchestra he set up in Canary Wharf and has done reviews of the Proms for the BBC, so let's just say he's pretty damned fussy about how things sound. He's had a pair of these for about a year, having owned the cheaper T2 versions for about 3 years before and said if I was thinking of the Denons then I really had to try these out.

I did do the usual period of Googling, including reviews here, but to be honest, it was the unequivocal nature of Tristan's recommendation, my knowledge of what a picky bugger he is, plus the fact that ACS offer a 30 day money back guarantee, that really made my mind up.

It was in-fact, the money-back guarantee that first made me realise that ACS are bit different. A money back promise on a pair of IEMs that have been custom moulded and hand made to fit my ears and my ears alone?! Clearly this was not a promise that any company was going to make if they didn't have total confidence in their product, and so it proved to be with these little beauties.

I chose to visit ACS in Banbury in person. It's only about an hour from me, and for the money involved, I thought it worthwhile. Basically I turned up, got given tea and biscuits and was able to have a chat with the MD Andy Shiach, who must be one of the nicest and most enthusiastic men I have ever met. One of their technicians then squirted pink goo in each ear to make the impressions, and after deciding what colour I wanted (I went for black) and how long the cable should be, I made my way home (without the goo-filled ears I hasten to add).

After a couple of e-mails updating me of progress, a package arrived about 10 days later (seems I cut the waiting time slightly with my personal visit), with my T1s safely packed up inside - and I do me SAFE! The picture shows a bomb-proof, water-tight Pelican case that is all part of the standard 'package' - as is the leather pouch, cleaning bits etc. All very impressive and really does add to the sense of value.

So far the whole experience had been wonderful. A very personal, bespoke service from a UK company who really seemed to be very proud of what they did and seemed very professional and knowledgeable. Also the quality of the product and the way it was presented was totally above reproach - absolutely excellent. 

Of course all this would have been for naught if they then failed to deliver, and even with all the VERY positive reviews on the web, Tristan's evangelical recommendation and Andy Shiach's compelling patter, I was still a very nervous man when I sat down, wedged them into my ears and turned them on for the first time. Yes I know I would have got my money back, but after all the anticipation, I think the disappointment would have made that seem like small consolation!

Now I've had a number of in-ear 'phones before and they have ranged from bloody awful (some £70-ish Denon things bought in haste at Heathrow airport before a flight to Auz when I realised I'd lost mine at security!), though to the really rather good Shure SE420s, but even the good ones had been slightly uncomfortable/fiddly to put in/difficult to keep in and a bit uneven in their tonal balance. These T1s on the other-hand are a total revelation.

They are completely comfortable once in place. The only time I am really even aware of them is when they first go in and are cooler than body temperature. As soon as they warm up (which they do very quickly), I really can't feel them until someone tries to speak to me and I can't hear what they're saying. Oh and I think my ears would fall off before they fell out.

Obviously the sound is the MOST important bit....

A brief demonstration of how amazed I am by them, is that I'm getting rid of my much-loved AKG K701s and Sennheiser HD580/600s and really don't have any regrets about doings so.  I had always been a total open-backed fan, so this is a BIG deal.

They are wonderfully balanced from top to bottom with no obvious emphasis on any one part of the range. Good recordings, especially those with great acoustic details (think Cowboy Junkies - The Trinity Sessions), really stand out and crap ones sound just that. Some might see that as a down-side, but I've always liked a system that 'tells it like it is', even if the story isn't particularly good news, because the up-side is that the good stuff really shines through.

The bit that has surprised me the most is how 'open' they sound. I know that seems a silly thing to say, given that they are about as 'in' my head as it's possible to be without sharing brain-space, but they don't have that shut-in feeling that all closed-back phones have always had for me. They don't sound as 'free space' as my AKGs, but the amazing noise isolation means that this is a happy trade-off for the immersive 'sound bubble' they put me in.

The T1s are both a great tool for peeling away the layers of a recording so you can hear how much (or how little!) love and effort was put into the performance and the recording, and also for just closing your eyes and getting lost in the moment - good live recordings are wonderful. Also I've noticed that good recordings of ALL ages are allowed to shine in their own way. Well recorded 'old' albums like Tapestry by Carole King, sound just as great as a more modern but equally fine example of recording and production like Welcome To The Pleasure Dome by Frankie Goes To Hollywood (this is a bit of a 'hidden gem' if you ask me). The difference being that the natural 'softness' of the tapes and valves of the older recording come through.
The other thing I discovered today on a noisy train back from Sheffield, is just how impressive the sound isolation is.  I was able to listen to really finely recorded acoustic tracks and still enjoy everything.  In that kind of environment, it would normally be a waste, but not with these.
Anyway I've rambled on enough. I'll finish by saying that this has been one of those special and rare discoveries, where looking for a solution to a problem has taken me somewhere I didn't expect. Combine the enjoyable experience of the purchase process, the quality of the product and the wonderful sound and it really feels like value for money, even if it can't be really. 


I just wanted to add a little something further about ACS themselves.  Let's be straight, they are not a big company - having visited in person, I know this to be true - but they clearly DO care a great deal and are a lovely, very dedicated team, who clearly have as many famous clients BECAUSE they care and go the extra mile.
I also liked the fact that while I was sat in a chair in the office with goo in my ear, a door opened and I could see straight into the lab where the guys where hand-building people's IEMs.  It's a personal touch that is very rare and I left feeling like I had become a valued customer and not just a number.
If you do take a punt on these, you won't be disappointed and I promise you that you will have invested in a product and company you can be proud of.
You wont regret your purchase. I have had nothing but good dealings with ACS. I love my T1s and have even bought a 2nd pair from here as a spare incase I have to send them back for warranty repairs...had to do that a couple of times and was lost without them.
Before the T1s I had a pair of SE530 and they were awesome to my ears...until the first time I fired up the T1s! I could not get over how so much better the T1s sounded, even though they were triple drivers too.
Great review, sounds like an awesome custom from a company that knows how to take care of their customers.
Great review, I recently got t1 and agree with your assessment wholeheartedly.  so comfortable and absolutely revealing of a great recording.  DSD are really wonderful, to listen to with these.  


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