Feliks Audio Elise
After several years of only owning solid-state headphone amplifiers, I decided to see what the fuss was about with tube amps earlier this year. On the surface, people seemed to be likening the technology with vinyl – something that sounded more natural to some folk but was antiquated in the modern world. Indeed, tubes have their disadvantages – a limited lifespan being the most immediate of them.
After hearing the Cavalli Liquid Tungsten at Can Jam London 2016, especially with a Sennheiser HD800, I knew there was more to it than just mere colouration of the sound. The headphone came alive with a sound that had more body than I was used to with it. I had to know more, and so earlier this year I started. First up was the iFi Pro iCan, with its solid-state to tube and tube+ mode switching. A hybrid tube amplifier that was not designed to be swappable, I found its sound to not be all that distinct between the modes. Next came the Schiit Valhalla 2, and I got a better sense of what tubes do.
Clashing directly with the stereotype of tube amps being overly warm and coloured, the Valhalla 2 added a bit more nuance to song mixes than I had heard before. Staging seemed wider too. There was something afoot here that I enjoyed, but I missed the more impactful sound of my solid-state options at the time. When I later got a Schiit Lyr 2, along with some spare tube sets to play around with, I came to understand the appeal behind swapping out, otherwise known as rolling, tubes. It was another hybrid tube amp, like the iFi, with a solid-state output stage that had only one gear to it – fast and punchy. Sure, you could put a slight spin on the sound here and there – but you couldn’t stop it from being its fast and punchy self.
When I bought the Feliks Audio Elise, I took note of the fact that it had slots for two power tubes and two driver tubes. Completely reliant on tube pairings, I was curious to see what had made this a much-discussed amplifier for tube rollers on Head-fi. I even knew someone who had one, and had spent €2400 on various tube sets. While not prepared to make that kind of investment, I wanted to understand the appeal on a basic level and felt that this was an inexpensive purchase to do so.
Specifications – From the Website
· Technical Specification - Model 2017
· Input Impedance: 100 kOhm
· Frequency response: 10 Hz - 60 Khz +/- 3 dB (300 ohm)
· Power output: 200mW
· Pre-amp Gain: 20dB
· THD: 0.4 % (300 ohm, 20 mW)
· Supported headphones impedance: 32 - 600 ohm
· Improved noise cancelling construction
· Headphones output: Jack 6.3mm
· AC: 230V/120V (power cord included)
· Dimensions: 310x205x170 [mm]
· 3 years warranty
Specifications – From the Manual
Elise is built with two 6AS7G (also accepts 6080, via the included adaptor) power tubes and two driver 6SN7 tubes. Power supply is based on a custom made stabilized toroidal transformer with electronic ripple suppression. The amplifier is equipped with automatic bias circuit, therefore no re-tuning is required after changing tubes. Please note that the optimal sound quality will be reached after approximately 30 – 50 hours of run-in.
· Impedance: 100 k ohm
· Frequency response: 10 Hz - 60 Khz +/- 3 dB (300 ohm)
· Power output: 200mW
· THD: 0.4 % (300 ohm, 20 mW)
· Optimal headphones impedance: 32 - 600 ohm
· Headphones output: Jack 6.3mm
· AC: 230V / 120V (region dependent, power cord included)
· Weight: 4.5 kg (7.7 lbs)
· Dimensions: 310x205x170 [mm] (12.2x8.1x6.7 [inch])
Build Quality & Features
After seeing the Feliks Euphoria, the flagship headphone amplifier of the company, at the London Can Jam 2017 – I saw that the designers adopted a “if it ain’t broke” mentality. The two amps are near identical in look. Both are OTL and both use the same power and driver/pre-amp tube slots.
It should go without saying that this amplifier can get really, really hot. This isn’t the heat of, say, the Schiit Asgard 2 (a class-A solid-state amp) – but is another level entirely due to the glowing tubes. Take care when handling these, Feliks themselves advise at least five minutes wait time minimum after switching off the amplifier before you swap tubes around. In fact, let me quote the manual:
Please note that tubes can reach operational temperature with excess of 150 Celsius (300 Fahrenheit) therefore tube exchange should be done with the device unplugged from AC power, after allowing the tubes to cool down and letting the capacitors discharge (minimum 5 minutes). Recommended ambient temperature for the amplifier to operate is between 15 and 30 Celsius (60 to 86 Fahrenheit).
The last part disqualifies the use of this amplifier in the summertime back in my home country, unless aided with ample air conditioning.
The actual unit is quite solidly build. I won’t do any drop tests or anything, but it looks like it will last a long time in a caring household. The volume knob is a satisfyingly smooth turn and the small LED in front is blue. There is only a slot for a single ¼ inch headphone plug, and I would recommend plugging in headphones after the amp has warmed up and unplugging before turning it off. The reason for this is that there is a loud and sudden cracking sound in the headphones if you a) turn the amp on while they’re plugged in or b) you turn the amp off while they’re plugged in. I believe Feliks told me that this was something they remedied in the 2017 version of the amp (mine is 2016), but I’d advise it regardless. I don’t even know if it would do damage to your headphone drivers, but I would advise it anyway.
Speaking of the 2017 version, I did ask them the details of how the new model differed from mine. They said that they learned some nifty engineering tricks to implement while developing the Euphoria when it came to sound isolation of the unit and decided to let those upgrades trickle down to the Elise as well. A specific example I was told was that the Elise was now less susceptible to that annoying interference from phone frequencies during an incoming call or text message. I’ve never really heard such interference in my older Elise, but people don’t usually call me anyways so.
On the back of the unit is one set of RCA inputs and one pair of RCA line-outputs – which in the manual are referred to as the “pre-amp mode.” There is a place to plug in your power cable of choice and a bright red on/off switch. I would have preferred the switch to have been in the front, but it isn’t a big deal.
Finally, the kinds of tubes that are officially endorsed by Feliks Audio to be used with this amplifier are printed on the manual:
Standard: 6AS7G (6N13S)
Alternatives: 6080, 5998, 6N5P, 6N5S, ECC230, 7236, CV2523
Alternatives: 6N8S, CV181, ECC32, 5692, 6F8G
While still being so new to tubes myself, I can’t advise what else you can try with these. However, I do use a RCA 7n7 driver tube pair on the Elise – I just needed a 7n7-to-6SN7 converter set from Hong Kong.
In my review of the Schiit Lyr 2, I mentioned how any tube rolling would just modify the flavour of the sound rather than overhaul it in any large way. This is because the amp’s output section was solid state, and not flexible at all. The Elise is able to roll both power tubes as well as driver tubes, and I have found it very sensitive to changes in both. The amp is not highly transparent by any means, but it responds very well to different tube configurations. To my ears, the Elise will always embody the stereotypical outlook of tubes – warm and euphonic. It is not muddy, however, and detail retrieval is quite good. The staging is not large by any sense, but it has a very natural depth to it that does positional audio justice.
When comparing the Elise to the newer flagship offering by Feliks, the Euphoria, I found that it had a warmer tilt to the sound than its elder brother. Indeed, the terms warm and gooey come to mind – but I would argue that this is a far more articulate experience in stock configuration than the solid-state Cavalli Liquid Carbon. There is no bloat with either Elise or Euphoria, but it was apparent to me that (even in the ruckus that is show-floor background noise) the Euphoria was set up to be a leaner, brighter but more detailed sound with wider staging. Indeed, there were some visitors to the Feliks booth at Can Jam London 2017 who preferred the Elise over the flagship, simply due to its warmer and thicker sound character. If that sounds more to your liking, then you might too.
The Elise’ customizability makes it wear different hats with ease. Need a faster sound for metal and rock? Switch to the Mullard 6080. Need a smoother, more relaxing tone? Use the stock Svetlana 6AS7G. A tube amp that changes with tubes, what of it? Well, this is a tube rollers dream in its price range and build due to just how much can be done with it. Forums have threads bursting with impressions from Elise owners for a reason, it’s an affordable OTL with good baseline specifications for dynamic headphones and the ability to explore different tube pairings comes easily to it.
But, on its own, it’s a dependable amp. As mentioned before, the staging is not especially wide (although this varies, again, with different tubes) and the sound has that lusher characteristic that I now find lacking in most solid-state amplifiers. The bass does not extend especially far with the stock tubes, but this also is changed up with rolling. Rather than stretching the sound out to reveal the low-level detail in your recordings, a task that is done to varying degrees by tube amplifiers, the Elise simply seeks to add tone to your music. This is not an amplifier for detail-retrieval fiends. This also is not the amplifier for lovers of planar magnetic headphones due to its low wattage. Indeed, I paired this with a few Audeze planars and found the sound lacking compared to what I know them to do.
The aforementioned tone was eye opening to me, someone who has primarily had experience with solid-state amplifiers in the past. The Schiit Valhalla 2, which I’ve reviewed before, is leaner and brighter than the Elise and then Schiit Lyr 2 (a hybrid tube amp) is more punchy and dynamic but without the natural sound that the Elise musters. By “natural”, I mean that the Elise is not etched or hard in its treble presentation, making it so the twang of acoustic guitars and the playing of grand pianos don’t sound artificially propped for the sake of utmost clarity. The sound isn’t neutral, but I often find things sounding (within reason, depending on genre) live instead of a pristine studio recording. I appreciate this, and it definitely and quickly taught me about the benefits of tube amplifiers.
Before I received my Elise in the mail, I was worried about its pairing with the Focal Utopia – an 80 ohm dynamic driver headphone that I use as a reference. It was not until after I had purchased it, and after a little research online, that I found that it had a rather high output impedance compared to the amplifiers that I’d used before. The output impedance is 40 to 50 ohms, depending on where you read. Using the amplifier with the Utopia would be breaking the 1/8ths rule of output impedance; that the headphone’s impedance must be over eight times the output impedance of the amplifier. Once I plugged the Utopia in, however, my fears were put to the side. It’s not just listenable, it’s very enjoyable as a pairing – adding a smoothness to the frantically detailed and hyper nature of the Focal flagship. Was it the most ideal pairing out there? Probably not, especially if you want to take steps to enhance the detail retrieval of the Utopia through an amp pairing. But is it wrong? No. Switching to my Dragon Inspire IHA-1, a transformer-coupled tube amplifier with only 4.4 ohms of output impedance, I found the background quieter and more revealing of detail. But when I switched back to the Elise and allowed a few minutes for my ears to adjust, I found it more than capable as a Utopia pairing.
The point of this section isn’t to say that you, the reader, absolutely need to buy a bunch of tubes for the Elise to properly enjoy it – but to detail what aspects can be changed by what. Also, the stock option of the Tung Sol 6SN7s might be discontinued as per a conversation I had with one of the brothers of Feliks Audio. He told me that PSVANE driver tubes might be the way to go for the Elise company-side in the future, as it already is with the Euphoria. Easier to find tubes matches, he said. I haven’t spent a long time with PSVANE, a Chinese company making tubes these days, but they sounded good enough at Can Jam from both Euphoria and Elise.
Svetlana Winged "C" 6H13C / 6AS7G
This is Feliks’ stock choice for both the Elise and Euphoria. On the Elise, it has a warm and slightly thick tone to it that gives a smoother sound overall. It is not particularly fast or heavy hitting, opting to be more laid back in approach. Vocals have a lot of body to them and bass extension is quite good, it definitely gelled with the ZMF Eikon that I have.
The major disadvantage of this pairing with the Elise is that it seems a bit veiled. Of course, this performance is closely tied to its inexpensive nature overall – but the same power tubes sounded quite different out of the Euphoria which is a testament to amp design over mere tube choices alone. The Euphoria had slightly wider staging and very inviting separation and detail retrieval. It was also leaner, to my ears, and a little more towards the bright side of things – while the Elise’s usage of the same power tubes yields a smoother, warmer and more pleasant tone that ultimately does mask micro-detail a bit.
I could not help but make comparisons to the Cavalli Liquid Carbon that I once had. I have no doubt that the Elise, using these stock power tubes, is still considerably the more articulate experience. Feliks knew what they were doing when they chose these for their two amplifiers. It’s a very good baseline sound with few shortcomings – a jack of all trades when it comes to tube options for the Elise.
General Electric 6AS7G
I’d go so far to call this the most v-shaped power tube of the three I’m talking about today. It injects a hefty amount of bass into the Elise’s sound, but not very bloated or distorted bass. While being clean, it is not all that much faster and punchier than the stock Svetlanas. It does have some weight to it, and kick drums are instantly more noticeable in mixes.
The midrange is a bit recessed, not overwhelmingly so but just slightly. I found guitars to sound a little hollow and male vocals to be emphasized over female by quite a margin. The treble extension is decent but misses out on some cymbal clarity and weight. Overall, I prefer the stock Svetlanas over this but I do appreciate just how much more of a punch these have when paired with electronic genres.
These bring the Elise more in line with my preferences these days. The Mullards are less tubey than the stock Svetlanas and are more geared towards a solid-state sound in terms of impact, dynamics and noise floor. I have no way of measuring exactly, but I can hear a quieter background with the Utopia over the stock power tubes.
Impact is an understatement of sorts as these power tubes provide a good punch to the sound of the Elise. With the Utopia, it’s a great pairing due to the headphone’s own fast and dynamic nature. I, quite frankly, hate when an amp holds the Utopia back in this regard – and so far I’ve only heard the Liquid Carbon do that by making the sound slower and a bit sluggish. The Mullard 6080s reduce the slightly thick and overly warm sound of the stock Svetlanas and open up the midrange to better detail retrieval. Micro-detail comes out better, with all the various percussion and instrumentation in Michael Jackson’s Don’t Stop ‘Til You Get Enough not being held back.
Bass is quicker on its feet, tap-dancing through the mix with precision and without any bloat or emphasis. Fans of a bloomier sound will probably not enjoy the Mullards, as it is leaner and more precise. Another noticeable upgrade from the stock tubes resides in the upper midrange and lower treble. The air region is better served by the Mullards, with string sections coming out better and faster. Grand pianos also have a less weighty and cleaner aspect to them.
Disadvantages that I can think of are probably headphone reliant in this case. While I very much enjoy the sound with my Utopia, I feel that it would hurt on the Sennheiser HD800. The treble is also more emphasized compared to the stock tubes, which is another reason why I believe the above. With a bad headphone pairing, and to those who are sensitive to treble, I feel that the Mullard 6080s would quickly become fatiguing. But for warmer headphones, I can’t recommend it enough for its price point.
Tung Sol 6SN7GTB – Made in Russia
These are the, as of September 2017, stock driver tubes provided with the Elise. It should be noted that, for an additional $150, you can upgrade to Chinese-made PSVANE driver tubes and that Feliks will be making the switch to only using those eventually as they have done with the Euphoria.
The Tung Sols have a slightly tall sound. What I mean by this is that it sounds like the notes occupy more space than they do on solid-state or even other tube options. This space is not width-wise, but rather vertical. A snare hit will sound larger than life instead of a more accurate sting in a mix. I won’t lie, this has a very pleasing sound to it as there is no lack of “real estate” to be used up here. I would not call it a reference sound, but it is fun to listen to and the Tung Sols share this aspect with the Ken Rad 6SN7GTBs.
Where it differs from the Ken Rads is in the air and treble presentation. The larger-than-life sound described above is not emphasized in the bass region on the Tung Sols, but rather in the mids and highs. You will hear a guitar solo pierce through the mix with additional emphasis given to it than other tubes and you will hear vocals sound very much like an intimate live setting.
Is it an especially revealing tube? I don’t think so, and I feel that it might have been chosen to (along with the Svetlana power tubes) give the widest experience gap between the Elise and solid-state amplifiers at its price point. Stick a HD800 into the Elise with its stock tubes and you will be treated to a sound that is less reference but more musical and, dare I say, enjoyable. With the ZMF Eikon, I found that the treble peak was smoothed out with the stock tube pairing, while the Mullard 6080s gave slightly more accuracy.
Sylvania 1950s Chrome Top 6SN7GTA
I would go so far to say that this is my reference 6SN7 driver tube these days, with it almost always being used in my Dragon Inspire IHA-1 when I’m critically listening. This is mainly due to its lean sound and detail retrieval, along with some of the best extended and natural treble I have in my possession.
How does it fare on the Elise? I actually don’t prefer it compared to it on my IHA-1. Perhaps this can be chalked up to personal preferences, but I feel that the Sylvanias don’t bring as much to the table on the Elise – while they are a stronger option for the IHA-1. This is because the detail retrieval boost is minimal on the Elise and I’m used to it being far greater.
Ken Rad 6SN7GT – Black
Let me preface this by saying that this tube is overkill with the stock Svetlana power tubes. These very much need the leaner and quicker sound of the Mullard 6080 to shine.
This has the deepest and most powerful bass of all the driver tubes discussed today. Couple that with its level of low-end control and you have a fantastic pairing for electronic genres, pop and rock music. With an overall warm sound in the midrange, and a slight bit of roll-off in the treble, I would not recommend the Ken Rads for a more analytical listening experience – but it is a balls-to-the-wall level of fun in how exhilarating it is for the right genres.
My earlier description of a “tall” sound with the Tung Sol 6SN7GT is taken a step further with the Ken Rad driver tubes. A good example of what I mean is in the song Dreams by Fleetwood Mac. The single note synth-line that plays in the chorus is normally thin and distant in mixes. On the Ken Rads, however, it is very front-and-centre and sounds thicker, meatier and livelier. Those are a lot of words to describe a mere synth accompaniment to a chorus, but imagine that effect applied to all instrumentation and vocals in a track. Huge and not at all reference, the Ken Rads make up for their lack of air by making music sound bombastic with a speaker-like quality.
RCA 7n7 (with a 7n7-to-6SN7 converter)
The opposite case of the Sylvanias, I actually prefer these more on the Elise than I do on the IHA-1. The RCA 7n7 have the capability to present delicate micro-detail and have a leaner sound than the stock option or the Ken Rads. The reason they gel more with a warmer amplifier like the Elise than a leaner and more analytical one like the IHA-1 is due to the treble region becoming harsher on the latter while this aspect is masked a bit on the former. This is just speculation on my end, but it does become a more fatiguing listen on the Dragon amp.
Another strength of the RCA 7n7 is its low price compared to the other detail-head driver tubes that I have, the Sylvania 6SN7 chrome-tops. When listening to jazz, it becomes obvious that these have good tonality for cymbals, snares and acoustic instruments. They do retain some body though, less than the Sylvanias but enough to make it a good pairing for jazz, classical and classic rock.
I have to reiterate this one aspect of the Feliks Audio Elise – it is not a powerful amplifier. As mentioned before, I really did not enjoy how the Audeze LCD series sounded from this. I wouldn’t recommend using this with any planars at all, actually. I wouldn’t recommend using IEMs with it either, as its high output impedance won’t be ideal. I’m still surprised that it sounds as good as it does with the Utopia – but it’s no coincidence that many prefer this for their 600 Ohm Beyerdynamic T1’s and Sennheiser HD800’s.
Dynamic-driver headphones are the way to go with the Elise, of that I’m certain.
The Elise met and surpassed my expectations from a first actual tube amplifier. It has a natural tone to it and can be altered with various tube pairings. Unlike the Lyr 2, it can be morphed in a more audibly meaningful manner to suit your preferences. Indeed, it might be that it could reach the detail retrieval prowess of its elder brother, the Feliks Euphoria, or even my Dragon Inspire IHA-1 with the right tube pairings – but I did not pursue those and will leave such discoveries to other owners. I do recommend reading the Head-fi threads about this amplifier though, there is a lot of interesting discussion going back several years.
One consistent thing about the Elise, no matter the tube pairing, was its ability to have a very smooth and enjoyable sound. After months with it, I understand fully why some would find it immediately more enjoyable than the Euphoria when they first heard the two at Can Jam. While the Euphoria is not sparse in tone, having its own strength and body, the Elise is more akin to what some people just seem to expect from a tube amplifier – with its stock power and driver tube pairing. It’s smooth, laid back and quite musical. It doesn’t try to be a low-level detail-resolving monster like some other tube amplifiers, but aims to be for those who want a more organic experience than their solid-state options with a gentle bloom in the bass and some midrange weight.