I wrote a little comparison using SR-007 which I assume is a known quantity to some people here. Please enjoy.
ES-1a and SR-007
SR-007 I’m sure needs no introduction, it was stax’ flagship from 1998-2011 until it was superseded by the SR-009 (and later the S). I already wrote a rambly SR-007 review, so if you want to know what I think about that then you should read it.
The ES-1a is far more interesting. It is the first (and only) headphone of the one-man venture ESLabs. The man behind it (he goes under bwck2000 on various forums) is someone who appears to have a lot of knowledge on electrostats, he even offers a repair service and can tout having serviced even an original SR-Omega and HE90. The ES-1a is heavily inspired by the SR-Omega in terms of the exterior.
ES-1a uses a pure copper stator that is only 0.3mm thick and appears to be quite a bit more open than the stax counterparts. According to the ESLabs website the idea is to have a normal stator that mimicks the characteristics of mesh stators (which SR-Omega and SR-X MK1 used). To put the 0.3mm stator thickness in perspective all stax stators are to my knowledge 1mm thick.
A brief description of ES-1a
ES-1a is a slightly shouty and slightly bright leaning headphone. It sounds more or less flat until right below 1KHz where it starts to rise a bit. I hear it as reaching a peak of about 3dB at about 1.5KHz. In other words it is noticeably forward in this range but I don’t feel a need to EQ it, though I will probably do so anyway. After the shout peak it drops off a bit, I hear the range from 2-4k as about 2-3dB below my percieved neutral. It has a big hole at 5Khz that I can’t hear too well in normal listening but is very audible when doing a sine sweep. I’m guessing it’s narrow enough that listening is not very meaningfully impacted. Moving into the treble it elevates a bit, personally I think the SR-007 has a very spot on 6-15Khz range (my hearing threshold) but the ES-1a has a similarly smooth treble with just a touch more energy. Overall the headphone is very smooth sounding with no obvious huge peaks.
Build and comfort
ES-1a is a big headphone, it weighs above 600 grams without cable (necklets be wary). The cups are machined from aluminum as is the yokes. The headband is a recreation of the SR-Lambda/SR-Omega headband but it appears the material used is nylon rather than the plastic stax used. It feels quite nice. The ES-1a has 2 different pairs of pads available, stock pads and «dark» pads. I am reviewing the dark pads here because I don’t find the stock pads very listenable in comparison. Stock pad leather doesn’t feel very good quality but the construction seems fine. Dark pads are made in a completely different leather that is much, much nicer. Some of the best earpads I have tried. Clamp is pretty low but you definitely feel the headphone on your head due to the weight. I can wear this for 8+ hours no problem though.
There are a few concerns/small notes about build though. First is strain relief. It seems cool but I’m not sure how much strain it is actually relieving, luckily Stax cables (which this uses) are very sturdy. Second is the pad attachment, this uses a similar design to SR-Omega where the pads are fastened to a plate and then attached with rivets, this is a very tiresome operation to go through every time you want to change pads, although it certainly is better than 009/S pad attachment. Third is the headband, the material is very nice but it has a solid piece going through it to stiffen it up a bit (think something like the Hifiman Arya headstrap). Which makes it feel not quite as nice as it could have been, but I am nitpicking.
ES-1a VS SR-007
Build and comfort
ES-1a wins for me but will most likely not do so for the majority of people. SR-007 is significantly lighter, has softer earpads and also feels more sturdy/high quality in total. It really does feel like something that costs 2000 dollars. My main issue with the SR-007 is simply that my head is too big. The strap rests against the headband and while I can get a good seal the comfort is still far from optimal. For anyone with a normal sized head (my head does not fit HD800) this shouldn’t be a problem and thus SR-007 would be the winner. For me ES-1a pulls ahead due to the larger amount of strap adjustment as well as cup articulation, though the weight difference is very noticeable seeing as ES-1a weighs almost double what SR-007 does.
My SR-007 has blu-tack mod.
In the bass department both these cans do very well, they have superb extension and articulation. SR-007 has what many would call more «weighty» bass, more akin to a planar than most electrostats. That being said the SR-007 feels very slightly more midbassy compared to the ES-1a. Both headphones rumble very well but SR-007 feels like it has slightly more slam/impact. The difference became much less after the ES-1a pads broke in a bit, probably due to better seal.
Where the SR-007 has very weighty bass for an electrostat the ES-1a leans towards the side often described as «ethereal sounding». It is very quick and very accurate but ultimately lacks as much slam as many people are seeking. I still find it to be among the better slamming estats I have heard though. If you don’t like how most estats present bass then I think it’s unlikely that you will find ES-1a bass to your liking. I find it adequate, however. Both these headphones are basically flat from 20-200Hz.
I’ve already talked a bit about the ES-1a mids above, so I’ll start by briefly describing SR-007’s midrange. While SR-007 does have among the nicest sounding mids I have heard there is no doubt that the 2-4KHz range is recessed to what can be called a pretty significant degree. The ES-1a betters it in this respect but could still stand to have a couple more dB in this range. Other than this the SR-007 is also among the least shouty electrostats I’ve heard which means the relative difference between 1KHz and 2KHz isn’t any more than what it is on ES-1a.
I find the biggest issue of the SR-007 to be that it is simply a bit mellow sounding due to the mids being so drawn back, it is tolerable but not desirable. In this sense I actually prefer the somewhat shouty ES-1a’s mids if we compare them both in stock form. I find that ES-1a has a slight increase in energy before it dips in the low treble, starting at about 3.5KHz.
Overall both headphones have mids as their biggest weakness (an eternal truth of electrostats it seems). That being said the mids of both headphones are quite good and absolutely tolerable unless you are extremely sensitive to shout.
Treble is without a doubt the strong point of both these headphones. I’ll say straight away that SR-007 has the most spot-on treble I have ever heard in a headphone. The quantity feels almost perfect and it has no ugly bumps in the response, as a result the headphone sounds very clean. The ES-1a is cursed with some kind of null at about 5Khz that deducts a couple points from treble performance, but as mentioned earlier I can’t find it really affecting my listening.
Like the SR-007 the ES-1a has what I can only consider fantastically smooth treble with a lot of air. The ES-1a does kick up the lower treble (except 5Khz) and midtreble by 2-3dB compared to SR-007 but this is still not what I’d consider an annoyance, although it certainly is bright leaning (SR-007 already has quite a bit of treble quantity compared to most headphones, especially the air region). Overall I prefer the SR-007 treble but the difference between them is slight indeed.
If the words «FR is the single determinant for sound quality, due to the minimum phase behaviour of headphones, as well as their satisfactory levels of distortion» makes you nod with satisfaction this is the point where you should stop reading, lest you have to see my impressions of non-existent, placebo-filled audio jargon. You’ve been warned, objectivists.
The ES-1a stages huge (by headphone standards, which means not huge at all). It is significantly wider than the more intimate feeling SR-007. The depth of both headphones is more similar though, with ES-1 being somewhat deeper still. I find SR-007 soundstage proportions to be very even in all directions where most headphones have significantly more width than they have depth, ES-1a definitely belongs in the «wider than it is deep» category (with 99.9% of headphones).
Overall I prefer the staging of the ES-1a, big soundstage is better than small soundstage for the majority of music, although SR-007 isn’t super small by any means either, and it can be very nice to have more intimate sounding headphones for certain jazz and metal especially.
Both of these headphones image very well, but I think SR-007 pulls out ahead just slightly. The SR-007’s imaging is among it’s best traits and while the ES-1a certainly isn’t a slouch in this department it still has to give way for the king.
This is imaging but in reverse. I think the ES-1a is ever so slightly more detailed/resolving. Both these headphones are what I would consider top-class in terms of resolution though so in my opinion the very minor difference here is relatively unimportant. Nonetheless I would like to do a 3-way A/B/C test with these 2 headphones and the 009(S) to say conclusively which resolve better.
The ultimate subjectivist meme, dynamics!
ES-1a feels slightly more dynamic to me than SR-007. It conveys large volume swings more convincingly to my ears, however slight. While I find these headphones very good in most regards I can’t say that is the case for dynamics, although I can’t say I hear major differences in dynamics between headphones. It seems to be mostly down to the music. Also headphone dynamics are big succ compared to speaker dynamics so I’m below average when it comes to caring about dynamics (not to mention like 50% of my music is DR6-7 or less).
Both the ES-1a and the SR-007 are great headphones, and while one could be content with either there are valid reasons to pick one over the other. In the end I think I’m gonna have to judge it a tie. For the first time I don’t feel like I own 2 headphones where one is clearly better than the other, rather they are purely complementary.
If you like big stage and a slightly brighter/more energetic feeling headphone then the ES-1a is probably what you want, if you can tolerate the weight that is.
If you like a more intimate stage with even more precise imaging and a more laid back sound in general, more akin to typical planars/dynamics in how it sounds then SR-007 is for you.
In my opinion, unless you are extremely sensitive to shout and hate EQ then you can go wrong with neither.