Kaldas Research RR1 Conquest

Kaldas Research RR1 Conquest Premium

Five years after it’s release, the continued relevance of this headphone today cannot be overstated.



If you don't like reading, here is the video version of this review


Introduction

Kaldas Research, founded by Aumkar Chandan, is India’s first high-end headphone company and the RR1 Conquest, released in February of 2019, is their first headphone.

The RR1 Conquest is an electrostatic headphone and as such, running these with a specialized amplifier is a requirement.
For the context of this review, all of my sound impressions come from it being paired with a STAX SRM-313, fed by the Fosi Audio SK02 DAC and SK01 Pre amp.

For this review we will look at the RR1 Conquest Premium, which retails for $650, however the regular version is available for $500.

What's In The Box

Inside the cardboard box you will find a wooden display case with an acrylic lid and laser etched Kaldas Research logo on the front.
Upon arrival, my lid was screwed in place with 4 small screws, so I had to use a screwdriver to get inside.



The shaped foam on the inside of the box does a decent job of storing the headphone safely in transit, and when removed, the box becomes a display case.



Also upon arrival, the two Allen keys required for adjusting the headband were inserted into the foam as seen.
I think with a bit of effort, a simple velvet fabric mod could transform it into an attractive display case.

Also included in the Premium package I found 4 extra suspension headband straps, two XL and two regular, and an extra set of ear pads.

There is also a lot of documentation to go through, including a getting-started guide and several user-guides about caring for and maintaining your RR1.
Also included is a measurement certificate unique to your headphone, taken with the G.R.A.S. 45BB-14 KEMAR with the KB5000/50001 Anthropomorphic pinnae and several other pieces of equipment listed on the certificate.
Included is the frequency response graph and the channel matching data.

Also included in the whole package was a 5 year anniversary brochure which goes over the history and journey of Aumkar and his company, a few shout outs and finally a hint of things to come.

Build

As usual, let’s start off with how it fairs as a tool to be used, an item to be worn and an object to behold.



This headphone is a beautiful curiosity at every angle and a well thought out design.
Every part of the headband is assembled with socket cap screws of various sizes, no doubt tightened to spec.
This approach rejects compromise and has been implemented with maximum care and attention to detail.

There is absolutely not rattle, creaking or high tolerance in any of the joints.
This is just about the highest build quality I have ever beheld in a headphone.

The ergonomics of the headband is however another matter.

The first oddity is found when you take this headphone out of the box. The two main large socket screws that connect the headband to the backs of the cups must be tightened to fit your head.



This is essentially a fixed cup-rotation mechanism that you set and forget.
Failure to comply with this step will result in a poor consistent fit and the headband will scratch the tops of the headphone cups.

The suspension headband is the same and requires setting with an Allen key.




This is definitely one of those cases where even if you have owned or tried out 500 different headphones, you cannot skip the first step of reading the instructions, and following through.

The 2nd thing about the headband is the clamping pressure.
I found it to be on the slightly extreme side so I carefully bent out the tight angles on the headband frame to alleviate this pressure.

No doubt some of you will find this approach barbaric, but it has worked just as well on my Grado SR80, Beyerdynamic DT770 and Sennheiser HD650, all of which have spring steel headband parts.

From my point of view, allowing the user to tension the clamping-force as they see fit is a crucial part of good headphone design.
Sure, most common types of headphone designs don’t needs this kind of adjustment, but the RR1 is clearly far from common.

After bending the headband, I found that I could easily wear it for over an hour or two without discomfort.



Looking at the injection moulded nylon cups, the design of their shape might appear to be an arbitrary choice that is purely aesthetic, but that is far from the truth.

Any seasoned headphone modder can tell you that these ‘half cups’ will eliminate the ‘seashell effect’.
Just cup your hands around the edge of these headphones, or any large planar and you will hear what I mean.
This effect is of course much more pronounced on the RR1 as most of the cup edges have been removed already.

In short, the design improves the overall sense of air and reduces unwanted resonance.

The protruding parts of the cups at the top and bottom won’t affect the sound too much, and also provide a lot of real estate for handling the headphones while taking them on and off your head and for the much appreciated mini-XLR sockets, making these one of the few electrostatic headphones with detachable cables.



Another interesting aspect of the cups are the two large ports or vents on the backs of the cups.

The only reason these exist is to prevent air pressure changes in the chamber to prevent the driver from flexing when taking these on and off or moving, otherwise the diaphragm can touch one of the stators and discharge.
It’s also a good way of preventing excess flex, which may damage the diaphragm over time, or quite suddenly with one strong pressure increase.

I’ve noticed that some users report that closing off these vents, or mostly closing them can lead to a superior bass performance, more on that later.


Going back to the cables, exposing the cables from the sockets to the transducers and making it part of the design is a stroke of genius.
Rarely does one get to observe such a clever twist on form following function.



The cable itself uses 2.5 meters of thick and heavy German Sommer Cable. This length is only available in the Premium package. The Standard version ships with a 1.5m cable.

I found that this cable is just good, honest, hard-wearing and no nonsense.

Due to the extra clamping force of the headphones, it’s extra girth and weight not become unwieldy or jerk the headphone around, and having the option to use DIY or custom cables with mini-XLR termination is also great, although it may prove difficult to find 3rd party 5-pin STAX plugs.

Going back to the cups, it’s important to mention there is almost nothing between the transducers and the open air.
Normally, drivers are protected by a rear grill or mesh, yet here we have a fully open back and front, protected only by dust screens.

I think on one hand it’s easy to criticize these two choices.
Grills will provide protection, but they can also ruin the sound.

Then there’s the choice of dust screen.
It appears to be a very common cheap type of dust filter fabric that you may find on other consumer electronics.

Now, on one hand I ask myself why they didn’t opt for the type of micro weave fabric that is found on the back of STAX Lambda drivers, but, as a modder I fully understand that if something does the same job at a fraction of the cost and can be easily repaired or restored at home even in 50 or 100 years when spare parts are no longer available, the choice becomes obvious.



The ear pads will also be a cause of some concern for some.
These pads are very large and open, but some of the thinnest I have ever seen.

Obviously the goal here is to provide as much comfort as possible with the least deviation, as any change in the distance from the driver to the ear will affect the frequency response.

I think my ears are either average or a touch smaller than average as I have never had problems with any over ear headphones, including small portable headphones, but I have to say, this is a very personal thing as I don’t mind when ear pads touch the outside edges of my ears.
I have only ever had problems with constant pressure from on-ear pads, so even though my ears also do touch the dust screens, it’s not a cause of discomfort.

In the end, the comfort is more than adequate for multiple hours of listening but the party piece of this headphones ergonomics is that it is the best headphone I’ve ever worn for light headbanging.

Moving your head around normally and looking up and down won’t make it shift in the slightest.


The Sound

This is not your average electrostatic.
It sounds like a headphone.

If you’ve auditioned (or own) the world’s best headphone system, the Sennheiser HE-1, you’ll have an idea of what I’m talking about, as the RR1 I think follows a similar philosophy.

Every single one of the vintage electrostatic headphones and the more modern STAX Lambdas I’ve tried out didn’t sound anything like the more common dynamics or planar headphones we’re used to.

The main two things people typically notice with those electrostatics are the lack of lower bass energy and the extremely detailed, ethereal treble.
This has of course led to STAX headphones in particular receiving both endless praise for having god-tier levels of detail, but also infamy at not being suitable for many music genres with either emphasis or strong bass in the mix.

Of course, there are always exceptions and while I’m over-generalizing, these stereotypes have often proven true for many including myself.
The RR1 however, subverts all of those expectations.

Imagine the staging and musicality of the Sennheiser HD650 with an almost completely neutral frequency response combined with the speed and detail of an electrostatic transducer.
This might come across as hyperbolic, but the only other headphone I’ve ever heard that gave me this feeling was the Sennheiser HE-1.

Of course, while these two headphones cannot be compared directly, the RR1 possess so many of the qualities I think many people will appreciate at a tiny fraction of the cost.


Let’s take a quick look at two frequency response graphs.



The first graph looks a bit broken, but the electrostatic nerds and measurebators will know what’s up.
This kind of problem has always existed when trying to measure STAX electrostatics: basically the graph does not accurately represent what you hear.

So while many STAX headphones do suffer from a lack of bass and sub-bass, the graphs have also sometimes exaggerated it, while emphasizing the bass around 100hz just before the observable roll-off.

So with that said, the RR1 graph with the rear vents closed presents a much more accurate representation of this headphone.
Listening to the RR1 back and forth with these vents open and closed, I barely notice any difference, so for the sake of this review we will focus on the closed-vent graph as the closest representation of how this headphone sounds.
(It is also significantly closer to the graph presented with the headphone certificate)

Personally, the only significant point of focus here is the dip between 1.5KHz that goes back up around 6KHz.
This kind of scoop has often been described as the method of achieving ‘artificial soundstage’. It does not negatively impact the sound or timbre and just makes the headphone sound smoother, bigger and more musical.

Aside from that, the slight roll-off on both ends was easily remedied by my Fosi Audio SK01’s tone controls.
Although throughout most of my listening time with the RR1 I barely ever touched the treble, adding only a little more bass, but as you can guess these small adjustments completely depend on the recording if required at all.

Ultimately this tuning reminds me of only two other headphones.

Firstly my modified Hifiman HE-500 (Green), which is significantly more neutral than the brighter stock version (Yellow) and is a touch on the warm side.


The RR1 sounds more neutral and has a bit less drama, but much more detail and far better separation.

Speaking of separation, there’s one test I really like to perform with high-end headphones, which is a sort of high-midrange & treble to bass separation test.
Basically, play a sample of electronic music and observe if the bass kicks reduce the volume of long consistent upper frequency sounds.

One such example of this is ‘Neckbrace’ by Ratatat, where at 18 seconds in, there is a hollow sounding percussive noise that reverbs for a few seconds.
There is only one headphone I have heard that can separate these sounds correctly; the Sennheiser HE-1, and for that, every other headphone has been utterly ruined for me, but it has also given me the ultimate benchmark for proper separation.

Going back to the RR1, I would need to do some careful A/B testing with other headphones I don’t have at hand right now, but I think it has the 3rd best separation I’ve ever heard, just behind or possibly equal to the T&A Solitaire P, with the LCD-X following somewhat closely behind.

To be clear, these two headphones crush almost all the competition in this regard, reaching about 85% of the HE-1’s separation ability, which doesn’t sound great at first, but almost all other normal high-end headphones dither around 70-75% of the HE-1’s separation ability.

But, I also know that most people don’t care as much about the niche aspects, you just want to know if it sounds good or not.
So, what’s the other headphone the RR1 reminds me of most?
The Oppo PM-1 with it’s original velour pads.



It’s not only close in tonal response, but also in it’s overall personality and performance.

When I tried out the PM-1 for a week or two, I enjoyed everything about it, but since my modified HE-500 was so similar and also had the lead on a more engaging soundstage I had no reason to acquire one for myself.
The RR1 takes everything I enjoyed at the PM-1, which is an easy A-tier headphone and puts it at an S-tier with it’s superior detail and separation, while retaining musicality.

When a headphone sounds as perfect as the RR1, even I could forgive it’s lack of expansive staging.
The bass is deep and fast with a planar-like timbre, but don’t push the bass EQ too much or you will encounter distortion faster than you would with a planar.

The midrange is on the smoother side and doesn’t artificially push vocals or other instruments to the front.

The treble is well extended but sacrifices a touch of air in order to reign in the piercing frequencies, so STAX lambda users will likely perceive the RR1 as being less detailed and airy, but these are assuredly near the attainable limit of detail reproduction for most mortals.


Conclusions

This is the singular best headphone I’ve ever owned.
It is a design and engineering masterpiece with a sound to match and has all but completely eradicated any lust I have harboured towards headphones costing multiple thousands of Euros.

It’s also responsible for allowing me to hear things in the music I have not heard before, which I am fortunate enough to say has not happened to me in years.

If you’re willing to invest a little patience into finding a good vintage STAX amp, this headphone including the modern source components also required to adequately run this headphone should have no reason to exceed 1000-1200 Euros.

In an age where high-end headphones alone are far exceeding this price point while surprisingly often offering far less, I can only give this headphone my fullest recommendation for anyone seeking flagship tier performance on a tighter budget.

In most cases bassheads and soundstage junkies need not apply, however for some people looking for the clear, definitive upgrade from the Sennheiser HD650 or Oppo PM-1, this is it.
Well, this or the Sennheiser HE-1.

as you may know electrostatics are my headphone and sound of choice.

previously reviewed the es-1a here and now here are my impressions of the kaldas rr-1 conquest.

Sound:
after researching a bit about these and how theyd sound, my expectation was that they would be in between the lambda series and the 007s that i have. and after listening for several weeks and comparing them, i think thats a pretty accurate description.

im not sure i'd call them a baby 007 though since to my ears they sounded closer to the l500s mk2s - without the shoutiness and better bass (non-blutack modded)


Bass:
been on a classical kick recently and listening to bruckners symphony no 7 was a great way to hear the warmth and texture of the bass these headphones can provide. much more substance than the L500s with a natural tone that just sounds realistic - full with life without being overly done or falling flat. (i understand you can blutack the lambdas to improve bass for example but really think headphones should be used as is especially after a certain price)

for electonica recently discovered paloma who's a dj producer out of san diego california. listening to her live set from february 18, 2022 at camino rivera was a wonderful way to spend a few hours imagining i was at the event in person. plenty of bass to make the music feel full and well rounded with melodies and vocals infused throughout the eclectic and international sounding set.

Midrange:
here i gave some acoustic classical guitar a few sessions with andres segovia -art of segovia and the guitar sounds like it would in person. though the rr1 does well here, i think this is where all electrostatics really stand apart from other headphones - with stringed instruments.

Listening to Phish “Harry Hood ” from 5/29/22 finished with another solid jam with a finely coordinated dance between all the instruments they play and are well known for integrated so seamlessly in their sets. again the rr1s sounded great.

as far as vocal music - been a bit nostalgic for some celine dion and mariah carey... and listening to 'because you loved me' and 'always be my baby' brings me back to the good old days when these songs were played all the time seemingly everywhere.

all in all i find the midrange well done and not at all offensive. (unless you like to get offended in which case you can always EQ to fine tune the sound to you liking... )

Treble:
the rr1 treble is tuned very well its not at all like the the L500mk2 (too much shout for me). in fact, i think it's a little in between the relaxed 007s and the es-1a.

i'd say this description is mostly from focusing on the higher frequencies like cymbals, violin and higher notes on the piano or guitar solo from Aerosmiths Crazy or Mendelssohns Violin Concerto Op 64 where i could sense the violin almost reach a point of unpleasant shrillness without getting there where it might hurt your teeth.

Soundstage:
the rr1s do have a much more intimate soundstage. i'd say much more so than the larger stage of the 007 followed by slightly larger stage of the es-1a. part of this may have to do with how close the drivers are to the ears. just from a quick visual inspection you'll notice its much more of a shallow ear cup than both 007 and es-1a, which may explain why (in addition to the driver and size of the driver)


Conclusion:
I'm very happy with these headphones. if i had to choose between these and the L300/500mk2s i'd go with the rr1s.

compared to the 007A and es-1a i currently own they hold their own. if i had never heard those two, i probably wouldnt know what i was missing... but since i have, i know that there's a lot of overlap between these 3 pairs and really only need 1.

curious if you've been in a similar situation, which did you keep and why? lmk in the comments!

Kaldas Research is a fairly new name in the industry, but it's one you should be paying close attention to.

Why? Money.

You see, in the world of business, it's all about money. If you own a business, you invest your time & money, and in return, you gain profit – you get food on the table and make a living out of it. Every business needs to at least return the invested amount of money in order for it to be able to operate. Ideally, you want to gain profit. What you do not want is to lose money, that's when things start going sideways. Just like hungry animals, business owners will do everything to get that food on the table, it doesn't matter how it's done, the goal is simple.

What makes Kaldas Research different is that its main source of income is not from its audio products. Its main business is in contract manufacturing and R&D. Behind the company stands a very young and passionate individual.

Mr. Aumkar, 23 years old, is the owner of Kaldas Research. He founded the company back in 2016. I have to repeat that Kaldas Research was never started as an audio company, but as a business whose profession lies within the field of R&D and contract manufacturing. Some of its partners are Fiat, Gillette, Colgate, and TATA.

So, how did Mr. Aumkar come to manufacture headphones?

It all began when he listened to his uncle's Sennheiser HE-60, also known as "Baby Orpheus". I believe this was his first encounter with Hi-Fi, and it probably sparked his interest in the audiophile world. However, his audiophile journey officially began in 2011 when he bought his first pair of personal headphones, the Sennheiser HD-650, and the rest is history. This would mean that he was only 14 years old at the time - impressive if you ask me.

Mr. Aumkar is more than just the owner of Kaldas Research. Before anything, he is a very humble and passionate man. It takes some true enthusiasm to start a family business at just 19 years old, let alone enter the competitive market of headphones. He produced the first prototype of his headphone [XP1] in mid/late 2018. It wouldn't be until 2019 CanJam SoCal that the RR1 Conquest, the official headphone model, would be released. What makes him different is that he is a true headphone enthusiast, something that is more important to him than business. In his very own words:
"I don't make headphones for a living, I am lucky enough to be in a position to have multiple businesses which prevent me from being pressured to constantly launch new products for quick sales like other manufacturers are. I don't care about sales"

He is clearly somebody who values true worth above business & sales. Integrity. There is a big difference between when you do something to earn money and when you do something with passion and earn money from it. It's the intention that is different. I think all of us (audio enthusiasts) are passionate about the hobby itself, however, very few took it to the level Mr. Aumkar has. He started to seriously invest himself into the headphone world ever since he listened to his uncle's HE60… It was headphone after headphone, the next thing you know, he has a whole collection of vintage, rare, and historically important pairs of headphones. Just judging from his Youtube channel, I was able to conclude that he is the type of person for who only the sky is the limit.

He is an incredibly humble human being. There was more than one occasion where he would be completely transparent about his headphone, and would even recommend other headphones over his own - he always stays honest.

What I want to say is that age doesn't matter. It is just a number. To see what this young man has accomplished with his passion is just beyond words. It's always sad to see a hobby where the older people discriminate and disrespect the younger ones. The worst part is that the older people are usually quite stubborn and just because of their age they refuse to accept that somebody younger is more knowledgeable than them — this can be the case when a younger person corrects them or understands the issue in something that they can't.


Principles

Mr. Aumkar didn't want Kaldas Research to be just another company in the headphone industry, he set very high standards for himself:
1) 100% Manufacturing and R&D to be done in-house
2) Not to outsource drivers from China
3) Approach vertical integration

When asked why it was so important to him to make everything in-house, he answered:
"I don't really have a straight answer to that. Maybe it's just personal. I'm doing this to make me happy – there are very few things that make me happy personally, and making something completely by myself is one of them."

"My inspiration is Horacio Pagani [of Pagani Automobil] and Christian von Koenigsegg [of Koenigsegg Automotive]. All these people, they are also passionate, and they make everything themselves. They don't go to other companies, take the parts, and make a recipe."

With this way of thinking, he really challenged himself to create something different — and in my eyes, he certainly accomplished that… at least if you are looking at it technically; the headphones themselves are 100% manufactured in-house, the only parts that aren't are the ear-pads and the headband.



Design

My first encounter with Kaldas Research dates back to 2019. I vividly remember stumbling upon its website and seeing the RR1 Conquest for the first time. My very first impression was quite interesting, to say the least. I remember having this unusual adrenaline rush and I also felt butterflies in my stomach… Something I would've never thought I'd experience for an audio product. I do know one thing, and it is that I was fascinated with the design aspect of it. There is something in the design itself that left me speechless, it didn't look like any headphone I have ever seen.

Looking back at that moment, I can say with confidence that I tend to get very excited for something new, something never-before-seen. In this case, it was the design.
What was the inspiration behind the design? The luxury automotive industry? Perhaps it was the female figure? Nope. It turns out that there actually was no true inspiration behind the design of the ear-cups, it was the result of pure experimentation in CAD.

"We didn't plan the headphone to look like it does. The RR1 initially wasn't supposed to be electrostatic and had an angled baffle plate system. We worked on this design for many months until we decided to implement an electrostatic driver and had to work around our design to implement the new driver. Then we experimented to accommodate the components like the driver trim housing, connector assembly, and other dust/grill protections."

Besides the ear-cups, there is one distinct design feature on the RR1 Conquest that stands out: the exposed wire. While it is definitely a subtle detail, it's something that Kaldas Research had in mind from the very beginning. Personally, I love it and think that it gives an authentic look to the headphones. There are, however, some who dislike this look, but this is something you can always expect when you are doing something different and new.

Before I cover the headband construction, I would like to shift the focus to a very important problem that Kaldas Research managed to overcome. Electrostatic headphones have always been this unique branch of headphones; they never were quite portable, always required a special amplifier to power them, and if they didn't have a fixed cable, they either had a removable one that was fixed in place with the help of screws (e.g. Dan Clark Audio Voce) or they had unique connectors (e.g. Warwick Acoustics' headphones, Stax SR-Omega, Kingsound headphones). You get the point, you couldn't simply go to the market and buy a "third-party" cable, it had to come from the manufacturer itself. Kaldas Research is the first manufacturer that has made an electrostatic headphone (pure push-pull design) with a fully detachable cable… Well, at least technically it is. Allow me to explain. I consider Kaldas Research to be a company that is in the headphone market, i.e. people know about the company itself. After all, it is a sponsor on Head-Fi. With this being said, I can say that Kaldas Research was the first company on the market to make an electrostatic headphone with a fully detachable cable, but I cannot say that it was the first to do it as a whole. Actually, there is a company that did it a couple of years before Kaldas Research. However, that company is virtually unknown for its electrostatic headphones, so it's safe to say that they are not known in the headphone market. What should this mean? Nothing more than the fact that you can neither say that Kaldas Research was the first nor that it wasn't; it didn't copy the feature from the other company because the Kaldas Research team was unaware of it. It comes down to the situation that two people came up with the same idea at different points in time.

Regardless, I think that featuring mini XLR connectors is a move in the right direction. It is both more durable and more convenient in terms of "third-party" cables. If future electrostatic headphones adopt this, it could become a standard and we could see cables for electrostatic headphones from the existing cable manufacturers.

Let's cover some details.

The headband construction consists of three main parts: the headband, the headband holder, and the headphone yoke. Each of these parts is very raw and exposed. One of the main advantages of this design style is that everything is easily accessible and replaceable. The headband itself is sandwiched between the main piece (the headband holder) and another small aluminum piece. If for whatever reason, you need to replace the headband, you can just unscrew the two screws and put in a new one.
The headband holder consists of a single piece that holds together the whole headband construction, this is why it can be called the main piece. Instead of utilizing a whole height adjustment system on the ear-cups, Kaldas Research implemented a headband sliding system. There are both pros and cons to this design. The pro being that it is highly adjustable and saves up both the material and footprint of the headphone itself. The con is that it is fixed in place and has to be adjusted manually (screwing & unscrewing). It works on a very simple principle: the headband holder has a slot in which a hex screw and another aluminum piece hold down the headband. To avoid scratching the inside of the slot, you will have to carefully adjust the height and fix it in place by tightening the hex screw.
And, finally, the headphone yoke itself. I must say, this is one of my favorite parts of this headphone, and the reason why is not so complicated. Due to the fact that the yoke both follows the figure of the ear-cups and gives them a floating look. I don't think the RR1 Conquest would be RR1 Conquest without either of these design choices. However, the design has its limitations — tilt is one of them. You see, the ear-cup size on this headphone is among the largest I have ever seen. It is very wide and makes achieving great tilt rotation virtually impossible. Mr. Aumkar had to attach the yoke to only one point (the back of the headphone) in order to achieve the look, but this also made the ear-cups vulnerable to scratching. If you rotate the yoke too far out, it will start digging into the ear-cups themselves, but you shouldn't run into this problem if you are careful and if you tighten the ear-cups in place.

I can't lie, from the very first time I saw the RR1 Conquest, I was convinced that it is one of the most unique headphones ever released. Having them in person, I can say that my opinion has not changed. And don't get me wrong, there are a lot of greatly designed headphones on the market, but there really is nothing like the RR1 Conquest. There are a lot of little details that aren't apparent until you really take a closer look: the headband holder is one of them. It actually follows the shape of the yoke, and much like the rest of this headphone, everything follows a specific figure. I also have to say that Mr. Aumkar and his team are very brave for going for such a design for their first headphone model!



Build Quality

The quality standards on this pair of headphones are nothing short of exceptional, and that truly doesn't come off as surprising. Once again, the Kaldas Research team put in some serious thought behind the material choice.

The RR1 Conquest wasn't always manufactured the way it is today. With the complex structure and design of the ear-cups, there were multiple issues that were faced when the headphones were made by 3D printing. For this reason, the manufacturing process was soon carried out by using the plastic molding technique. However, even with this method, there is quite a lot of hand processing that is required to achieve the matte-black finish.

Talking about the finish, the surface of the ear-cups is something different. This is the highest quality plastic that I have seen to date — at least when it comes to the plastic used on headphones. The hand processing obviously paid off because the smoothness of the surface is just out of this world. It feels high-quality, looks high-quality, and is in fact high-quality. You will notice that there are two parts of the ear-cups — both of them are made of the same thermoplastic and have the same finish. One of the problems that occur very often with thermoplastic is that over time it becomes sticky due to polymer degradation. Kaldas Research was aware of this problem and took the necessary precautions to avoid it. Mr. Aumkar assures that the material will never get sticky or rubbery over time, but will be polished (over the span of years of use) due to the oils in our fingers. Keep your hands clean!
Note: It is not recommended to clean the ear-cup surface with anything wet/damp. If any cleaning is necessary, do it with a dry cloth.

The rest of the construction is built to be quite robust. You have the headband that is made of spring steel, the headband holders, and the yokes that are made of anodized machined aluminum. Speaking of spring steel, there was absolutely no ringing present! This is something that has been a problem in some headphones, and I am very glad that it is not the case here.

This is a very well-built headphone, to say the least. I find it interesting that the manufacturer tackled a common problem, yet they didn't address it on the website itself. The company clearly assures longevity, and if anything ever goes wrong, you can count on being taken care of. If looks matter to you, the only thing that you need to keep in mind is to take care of the ear-cups. If you want to be an extremist, you can handle the headphones with gloves on... but that's a bit too much, isn't it?



Cable

I think that at this point everybody knows I am very picky and strict when rubber cables are in question. Sennheiser HD598's cable has been my gold standard since forever. You probably heard me once or twice speaking about how robust and high quality that cable is, and whenever I see a rubber cable, the least I expect from it is to meet the quality of the Sennheiser's cable.

Good news for you, Kaldas Research used a high-quality rubber cable. What a relief. No, it is not a 6N silver cable with crazy technology inside. It's just a cable. A good cable. In terms of available information, it is a 24 AWG, OFC (oxygen-free copper), shielded cable. Since the cable itself features written text on it, I was able to find the exact model. It comes from the German manufacturer Sommer Cable, and it is their 200-0551 model. Surprisingly enough, it is thicker than HD598's cable but feels just about the same in terms of quality. The connector housings are made of the same smooth matte-black plastic that the ear-cups are made of — very lightweight and pleasant to the touch. One the headphone end, you will find mini XLR connectors, while you will find Stax 5-Pin Pro BIAS on the amplifier end.



Comfort & Fit

Is the glass half empty or half full? If there was one area that I would recommend to be improved, it would be this one.

So, here's the thing: I had worn the RR1 for several hours, and although there were minor issues, I cannot say that the headphone is uncomfortable. One of the issues is the thickness of the ear-pads. Due to their extremely thin nature, some people had the problem where the upper part of the ear touches the fabric cover (I'm one of those people). Most of the time I did not feel any discomfort, but sometimes I would experience fatigue, and that's when I would have to move the ear-cups around. If the ear-cups weren't vented, this could have presented a real problem, because you would run the risk of causing condensation within the ear-cups themselves… electrostatic headphones and moisture don't quite get along. Just recently, a number of people reported moisture inside their Apple AirPods Max. This being said, the most ideal solution would be to increase the thickness of the ear-pads — but that completely changes the sound signature. Overall, it is not an easy thing to fix.

Something that personally bothered me is the limited rotation of the ear-cups. Vertical rotation is perfectly fine, but you can damage the ear-cups if you are not careful. What I found to be lacking is the pivot (horizontal rotation). To give you a better idea, I would rather call it wiggle than horizontal rotation. This usually wouldn't be such a big problem, especially to those who have a decent amount of fat on their face, but those with a slimmer face may find it limited.

I didn't find any other issues besides the two mentioned above. As I said before, I had no signs of discomfort even after wearing the headphones for several hours. Something that I did see bothering some people is the material of the ear-pads & the headband. While it would've been nice to see some genuine leather, the used PU leather felt pleasant to the skin and provided a nice seal. No sweating, no hot-spots. And while the headband is quite literally just a strap of artificial leather without any cushioning, it did not hurt my head. As a whole, I'd rate the comfort around 8/10.

Update (2021/01/31): The headband ripped on both sides. I managed to fix it with some superglue and leather scraps. A way to fix this would be to reinforce the headband on the part that is placed in the headband holder, that's the most fragile spot. Using a small piece of ripstop fabric would stop this altogether, so I recommend Kaldas Research looks for a solution.

Sound

If there is one popular opinion about electrostatic headphones that I keep hearing over and over, it is that they lack lower frequencies. And while this does seem to be the case with the majority of electrostatic headphones on the market, RR1 Conquest is an exception. The price may fool you and imply otherwise, but once you hear these in person, you will get what I am talking about.



Lows

As somebody who spends a lot of time on the web and on audiophile forums in general, I am constantly surrounded by opinions about products. Sometimes a person really enjoys a particular product, other times somebody else hates it. Here is a short story I'd like to share.

Many of you already know that Kaldas Research is an official sponsor on Head-Fi. If you have been closely following Kaldas Research, then you are probably aware of the dedicated RR1 Conquest Head-Fi thread. I have been following that thread from the very beginning, and haven't stopped since. From doing so, I was able to form some expectations from this headphone – some liked it, some didn't. So, when my RR1 Conquest arrived and I gave it some listening time, I found myself disagreeing with a particular opinion. I vaguely remember some people or one individual who found these headphones lacking in the lower frequency region or said something along the lines of "the bass cannot be compared to dynamic driver headphones", and I simply couldn't get that around my head once I listened to these in person. Not only do I not find them lacking in bass, but would say that the bass quantity levels are on the same level as on some dynamic headphones — this alone is mind-blowing for an electrostatic headphone! But hey, I am listening to these on an amplifier that is almost 15 times the price of the headphones themselves… so I can't really compare my experience to the one where the headphones were paired up with an entry-level electrostatic amplifier/energizer.

"Psychic" by the American duo DARKSIDE is one of my favorite albums to just let go of everything and relax to, but more than that, it is a great album to listen for low-frequency qualities.

It's hard not to mention "Frank", by the one and only – Amy Winehouse. Explicit lyrics, raw vocals, and thumping lows. That's my cup of tea! In fact, I think that "Frank" doesn't get enough praise and attention, it's always "Back To Black" that steals the spotlight.
"Stronger Than Me", "screw Me Pumps", "Moody's Mood For Love", "October Song", "Amy Amy Amy", and "Outro" ("Brother", "Mr Magic") are the tracks that I found to stand out for their low-frequency presence. The RR1's sound performance in this region is truly exceptional. The depth is there, the punch is there, and the body is there. And when I say "exceptional", I mean exceptional.

What makes this pair of electrostatic headphones special is their ability to capture lower-frequencies, in particular, sub-tones. As I mentioned before, it is widely accepted that electrostatic headphones are not the most capable when it comes to lower-frequencies, let alone sub-frequencies. Let me tell you this: for a $500 electrostatic headphone to be able to produce such clean sub-tones is beyond amazing. To be fair, it is amazing that it is able to produce sub-tones at all.

As I am not trying to be a poet, I will give you some music references¹. Right away, we can talk about "Brother" by Amy Winehouse. While the song is fairly simple-structured and Amy takes it easy with the vocals, the beat is more aggressive. You can listen for the rumble at around the 0:02, 0:08, and 0:14 minute marks. This rumble repeats itself throughout the song, but what I want to focus on is the weight and depth that it holds. It is very audible and clear on the RR1 – no distortion, it is a clean sub-bass tone. What makes this particular part special is that there is a true sub-bass rumble (a sub-tone that you feel).

Another track where the sub-bass performance stands out is "Theme for The Irishman" by Robbie Robertson. It is not only a great composition but also another track that features some beautiful low-frequencies. The part I want to focus on is at the 1:46 minute mark, this is where there is a sub-frequency undertone. Once again, RR1 didn't disappoint and reproduced a clean rumble. There is something gorgeous about the overall tone of the cello at this particular part, give it a listen.

Not to make this any longer, I think it's pretty obvious that this headphone is quite capable. However, as it is an electrostatic headphone, it has its own limitations. So far, there has only been one track where I heard this limitation — "Why so Serious?" by Hans Zimmer. It is my standard testing track for sub-bass. Electrostatic headphones differ quite a lot from dynamic driver headphones, both in sound and in driver design, and there is an explanation behind the limitation that was audible in this track. While dynamic drivers have the benefit of the maximum excursion, electrostatic drivers are much more fragile and do not move a whole lot – to be more specific, they only have around 0.5mm of displacement. This is the reason why most electrostatic headphones struggle with lower frequencies.
Let's get back to the track. As usual, in "Why so Serious?" at 3:26 minute mark, there is a drop and from then on there is only sub-bass present. Instead of a clean sub-bass performance, there was an audible rattle. The reason why this happened is because:
1. the drivers reached their maximum displacement point
2. the small diameter of the electrostatic driver and the fact that the ear-pads are very thin
In other words, extremely low frequencies at a certain SPL level (listening volume/loudness) will cause the headphone driver to bottom out and the result is an audible rattle.

Besides on this one particular track, I've never experienced any rattle/distortion. RR1 has a very clean and deep low-frequency response. The mid-bass remains a truly full-body that has a strong punch & thump.



Mids

Do you remember the moment you fell in love with music? Perhaps it was on a specific audiophile system and you just experienced this close connection with music, this specific happiness? So far, I experienced it two times: when I hooked up my Sennheiser HD 598 to the EarMen TR-Amp (after using the headphones without a dedicated amp/DAC for several years), and with the iBasso SR2 headphones. Well, I am happy to say that I am falling in love with music once again with the RR1 Conquest.

Actually, the very album that became apparent to me was Daft Punk's "Random Access Memories". To be honest, I find it very funny, because there seems to be ever-growing hate for it. There is a set group of people within the audiophile community that shares the same mindset: when an album or a track gains mainstream success, it is automatically dismissed as being good… It's similar to the rejection/discrimination that "Stairway to Heaven" faced.
On the other hand, these are also people who strictly listen to mainstream and limit themselves in that bubble. I don't necessarily support either of these groups, I just urge people to listen to music without putting any labels or limitations on the music itself. But that's just my opinion, I listen to music without a box around it — I don't listen by genres or by streams, I just listen to what my inner self & ears like. At the end of the day, for me, it is all about the love for music.

The guys from Daft Punk are perfectionists, they pay attention to details nobody would notice or hear but them themselves. Not to mention that the best musicians and recording studios were used to make this album. This being said, I think that anyone who actually took the time to look deeper than just the mainstream success would be able to respect their craft.

My love for strings dates back to when I was introduced to Led Zeppelin's "Stairway to Heaven" and Deep Purple's "Soldier of Fortune". From that point on, I began forming my personal taste in music, I started listening to music that I enjoy. I guess both of these songs share a similar story and success, but Led Zeppelin released theirs about 3 years earlier.

"Strange Fruit" by Nina Simone is a powerful… it's kind of depreciative to call it just a song. It is much more than that. It is the gruesome reality we live in, and it is still relevant today. A true shame. Besides its lyrical message, let's focus on the vocals. Nina Simone's vocal performance in this particular track is very textured, it's anything but monotone. Throughout the whole track, there is an audible edge to her voice when it accentuates (peaks), but the most prominent one occurs from the 2:23 - 2:34 minute marks. Here are some other tracks that share similar upper mid-range quality:

Jeff Buckley – "Forget Her" (vocals)
Nina Simone – "I Put A Spell On You" (vocals)
Joss Stone – "The Chokin' Kind" (vocals)
Fleet Foxes – "Fool's Errand" (vocal at 1:41)

As I always say, a good headphone should not hide sound qualities that are meant to be there in the first place; if a track is of an essy nature, the headphone should reproduce it — and that's exactly what the RR1 Conquest does.

Vocals aside, when it comes to strings, I look for two main things: the low-end extension and the high-end extension. If either of these is slightly off, a stringed instrument will not sound right. Timbre has a lot to do with this. If you listened to an acoustic guitar or a similar instrument before, you know that it sounds like it is being plucked. Well, this is what I look for in headphones — whether they can make strings sound like strings. "Airy" is another important characteristic of stringed instruments. A headphone that lacks spaciousness will not sound pleasant, and there's nothing that turns me off more than a claustrophobic headphone. Here are some string reference¹ tracks:

Joan Baez – "Diamonds and Rust"
Joan Baez – "Song of Bangladesh"
Pink Floyd – "Goodbye Blue Sky"
Pink Floyd – "Hey You"
Yao Si Ting – "One more time" (to be honest, the whole album Eternal Singing - Endless Love IV is absolutely stunning)
Judas Priest – "Beyond the Realms of Death"
Deep Purple – "Soldier of Fortune"
Roger Waters – "5:11AM (The Moment of Clarity)

RR1 Conquest is a highly dynamic headphone, there's no doubt about that. I think it all comes down to the extremely well-executed airy nature of this headphone. Basically, what I mean by this is that each element in the mix has room to breathe — and this room is also what allows more detail in the music itself. I could completely focus on a single element (such as a vocal) and not feel like another element is getting in its way. A huge canvas allows space for more detail, while a smaller canvas can only hold so much "paint". I like to call this "canvas" depth (not to be confused with the same term that refers to distance!). RR1 has an immersive mid-range presentation that has both a great upper and lower mid-range extension. This combined with the open nature, great depth, and natural tuning is what makes it so good.
Hats off to you, Kaldas Research!



Highs

To top it off (excuse the pun), let's talk about sparkle, shall we? Just like many people say that electrostatic headphones don't have enough bottom-end, they say that electrostats usually have aggressive highs. So, where does this idea come from? I believe it is from poor amplification. However, this is only an assumption, I would have to listen to some widely used electrostatic energizers in order to see if that's the case – or it is the entry-level electrostatic headphones (which I also didn't listen to).

RR1 remains fairly transparent in the treble region. I can confidently say that I did not come across sibilance. As mentioned before, the treble response is very transparent and clean — no distortion is present. Besides the negative stereotypes, it is often talked about how "fast" and clean the high-frequency response is on electrostats, so it comes as no surprise that the RR1 performs well in this region.

Commercially successful and popular among the audiophile community – "Aja" by Steely Dan. You will often see this album pop up in one of those "best audiophile albums" lists, and it's because it is a well-recorded and mastered album. But that's not why I am mentioning it. I actually want to talk specifically about the quality of the percussion that is present throughout the whole album. Much like Daft Punk, Steely Dan used unique recording techniques and obsessed over details, going to similar extents as Daft Punk did with equipment. What I like about the RR1 is how snappy (fast attack and slam) and crisp the percussion sounds. I am sure you are sick and tired of reading audiophile terminology without any explanation or correlation to sound, so let me explain what I mean by "crisp". I consider that term to refer to the specific quality and sound character that percussion has, essentially what makes a percussion instrument sound like a percussion instrument. If you listen for metal percussion instruments such as the cymbals and hi-hats, they should sound steely (excuse the pun once again)… On a serious note, the percussion had the edge and the shine that it was supposed to have, but it was never too aggressive or piercing. Speaking of percussion and aggressiveness, "Stairway to Heaven" by Led Zeppelin is another great example. The most aggressive point is right around the 7:18 minute mark, which also happens to be the climax of the whole track — or as Jimmy Page would describe it: "It's like an orgasm at the end". I have to say that I agree with Plant, that's exactly how it feels like to me. I got a little off track again, didn't I? The referred part (7:18) sounds forward and has that sparkle from all the high-frequency energy.
Here are some other percussion reference¹ tracks that share the crisp quality:

Bill Withers – "Moanin' and Groanin" — tambourine present throughout the whole track has a snappy quality
Dire Straits – "Money for Nothing" (from 1:49 - 3:38) — I talked about this track in the past, it shares the following qualities on the RR1: snappy, clear, crisp
Roger Waters – "4:33AM (Running Shoes)" — although less forward and present, the percussion sounds crisp
DARKSIDE – "Heart" (1:06) — a single snare hit is played, it is very sharp and bright, but you can also hear its delay

Here are some reference¹ tracks that showcase sparkle from guitars:

Fleetwood Mac – "Go Insane - Live 1997" (2:19) — although the whole track features a poppy acoustics guitar, the plucked string at this specific minute mark stood out and was brighter than the rest
Judas Priest – "Beyond the Realms of Death" (4:30 – 4:38) — during this time period, Glenn Tipton's guitar solo sustains a higher-pitched note that sounds smooth and not too forward. You can actually hear the acoustics guitar plucks above Topton's guitar

Finally, for sibilance, there is one track that every headphone in my hands has to pass: "Stop Trying to Be God" by Travis Scott. I still haven't come across another track that holds such a clean high note for the amount of time Stevie Wonder holds it in this track. However, there is one track that shares a very similar sound — "Portia" by Miles Davis. On both of these tracks, there was no distortion, and the peak notes were sharp and bright, but not sibilant, and I should say that the RR1 proved its ability to produce sparkle.



Soundstage & Imaging

I mentioned before that this headphone is very airy. In fact, I consider it the most open headphone currently in my collection.

To start on a lighter note, let's talk about two tracks from Pink Floyd: "Hey You" and "Dogs". In the first track, right around the 1:17 minute mark, the whole song catches momentum. At this part, the drum is slightly off-center to the left side, while the guitar strumming is panned to the far left & right, and the vocal remains dead center — all of this together results in a very spacious-sounding track. The latter song, "Dogs", features two acoustic guitars in the introduction (0:00 – 3:33), one is panned to the close left, while the other one is panned to the far right. However, for me, the standout parts are at the 3:48 & 3:56 minute marks. The first drum part (3:48) includes five distinct drum hits: the first one is at the center, the second is slightly panned to the left, then the one following that one continues to pan farther to the left, and finally, the last two are panned to the right (the first is closer, the second one is farther away). The second drum part (3:56) features six drum hits: the first one is at the center, then the following three each go farther to the right, the fifth hit comes back around to the center, and finally, the sixth hit is panned to the close right. RR1 presents this space very well, with each drum hit being at a very specific position. This is where you are able to hear RR1's pin-point imaging ability.

I think that the airy nature of the RR1 is not coincidental at all. In fact, I firmly believe that there are two factors that greatly contribute to this headphone's airiness:
1. Thin ear-pads
3. Transparent design of the ear-cups

Having the driver closer to the ear not only makes the sound fuller but also expands the soundstage by having the outside of the driver (the other side of the headphone) closer to the ear – I believe that this is what allows the soundstage to be so wide and immense. On the other hand, the "transparent design" of the ear-cups should have an impact on the soundstage. What exactly do I mean by "transparent design"? If you look at the ear-cups on the outer side, you will notice there is no solid grill or anything of that kind, only a protective dust cover (the same goes for the inner side). The design is very naked, and if you are an extremist, you can take off the cloth altogether.

What made the RR1 so enjoyable for me is how layered the music was. This is the room I talked about earlier. You can truly separate out and focus on almost every element in the mix. It doesn't sound like you are listening to headphones. Since vocals are usually placed in the center, you can choose whether you want to listen to the mix as a whole, or whether you want to isolate a single instrument.
Here are some tracks that can be used as a reference¹ for soundstage & imaging:

Yosi Horikawa – "Bubbles" — an outstanding track that showcases the soundstage width. Without exaggerating, I was able to hear at least 30-50 cm outside of the ear-cups at certain points in this track (horizontal soundstage)
Pink Floyd – "Hey You" — acoustical guitar at the beginning placed upright (vertical soundstage)
Daft Punk – "Get Lucky" — the hi-hat sounds as though it is placed above (vertical soundstage)
Pink Floyd – "Dogs of War" — also sounds as if the "growling" is placed behind the ear (depth)
Pink Floyd – "Outside the Wall" — sounds as if the vocal is behind the ear (depth)
The Alan Parsons Project – "La Sa Grada La Familia" (3:28) — from this point on, there appears to be a snare that is placed above. Also, in the introduction, there is a helicopter that too sounds like it is placed above (vertical soundstage)
Rare Bird – "You Went Away" (1:58) — at this part the percussion sounds as though it is coming from the distant upper-right side (vertical soundstage)



Conclusion

Kaldas Research is really doing something different. I am truthfully short of words. A person of just 23 years of age was able to successfully create a headphone that does not copy anything in the existing market. That's not even the most amazing part about it all, I find Mr. Aumkar's approach much more fascinating. Where do I even begin?

When existing owners of the RR1 Conquest started discussing the possibility of an updated model, Mr. Aumkar went on to explain why there will be no "RR2":
"Of course, there will be future products but the RR1 was always made to be a standalone product with no successors."

Following up with:
"New products tank the value of old headphones and make them essentially worthless all while also damaging the brand's value.
Furthermore, I am also against the concept of discounting. No product will ever be discounted under my watch. Discounting is a disrespect to the customers who have paid full price and also shows a company's perception towards their own product."

How brave and mature to think like this at such an early stage as a manufacturer, huh? Just, wow. Talking is one thing, but taking action and keeping your word is on a whole different level. Time will tell whether Mr. Aumkar will choose to maintain this approach in the future. Who knows, maybe his customers will urge him to change it because they want an updated version and would be interested to buy it, or maybe Mr. Aumkar comes up with a solution of his own.

In terms of the product itself – the RR1 – it's a one of a kind headphone design-wise, value & price-wise, and sound-wise. I cannot resist saying that for only 500 bucks, this headphone puts a good number of electrostatic headphones at this price range & above to shame. I am not saying the RR1 is perfect, there are definitely some things that can be improved, but when it comes to the sound performance, I wouldn't change a thing. My favorite part about the RR1 is how open it is. Besides the two factors I mentioned before, I think that the lightweight nature of it plays a major role in the experience as a whole. The RR1 simply offers a true out-of-your-head experience, and it neither sounds nor feels like you are listening to a headphone.

Performance that left me speechless:

Conecerto Italiano – Nisi Dominus: Cum dederit (Salmo 126), RV 608

All I can say is that the RR1 is a serious step forward in my audiophile journey. You can certainly call it budget-friendly, but you cannot call it an entry-level headphone, because it is far from that. Kaldas Research is surely doing something right when the RR1 is getting compared to +$2000 headphones.
Mr. Aumkar is a perfectionist, a true enthusiast, and somebody who is making headphones with pure passion. It's near impossible to truly understand this unless you read his presence online & had the chance to speak directly to him. I know that Mr. Aumkar has always shown his gratitude and respect towards the people of significance in the headphone industry, and I know how much he respects the legends. I am more than happy to say that he is definitely in my book of legends, though he has yet to "prove" himself to the industry and the rest of the world — and I have no doubts that he will accomplish that in no time. He has already been recognized and has received the support of some of the greats in today's industry (Mr. Sankar Thiagasamudram – Founder & CEO of Audeze).

Last but not least, I want to personally thank Mr. Aumkar for having the trust in my vision and in the quality of my work. I would also like to take the time and appreciate how much Mr. Aumkar did for me to make the cooperation go smoothly. He went out of his way to ensure I don't run into problems, and for that, I am very grateful and thankful.

Finally, I want to end this article with a quote that shows how down to earth Mr. Aumkar is:
"After the Beyerdynamic visit, I founded Kaldas Research. Kaldas is named after my Grandfather - Mr. Gokaldas Chandan, a man who started literally from zero to support his family and grew a business from absolutely nothing. Something, I won't ever be. In comparison, my hardships are a joke."

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Setup:
MacBook Pro (Early 2015) > EarMen TR-Amp > Soltanus Acoustics Fortissimo (direct non-affiliate product page: here)
AC power cable: ViaBlue X-60 (direct non-affiliate product page: here)
Interconnectors: ViaBlue NF-S1 RCA (direct non-affiliate product page: here)
Accessories: ViaBlue TRI (black) spikes used on the amplifier (direct non-affiliate product page: here)

Overkill? Yes. I wanted to see what these headphones are truly capable of. I am very well aware of the fact that the power cable alone costs more than the headphones themselves. Obviously, this is not a setup you would buy if you were to only use the RR1 Conquest, this is a setup that is versatile — it is for somebody who owns several pairs of electrostatic headphones and/or loudspeakers.

Reference¹ — the mentioned reference tracks are carefully chosen by me to make it easier for the reader to understand the referred terms & sound characteristics. By no means did I judge the headphones based on a couple of reference tracks!