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Corda Headamp-2 – the review

post #1 of 51
Thread Starter 
Back from my roller-coaster ride...

Well... it seems that I'm the first Head-Fi-Member who has bought a HA-2. So to write a review on it involves a considerable measure of responsibility. Because for many readers it necessarily represents a point of orientation, even if they reasonably assume that it's accomplished from a subjective point of view and with specific devices. I can't but point out that my perception is a very personal one, stamped by my audio career and of course my individual setup. Not unimportant: my vocabulary of the English language is limited; this may cause that some of my descriptions are not completely adequate or mistakable, e.g. with some adjectives. Please spend some fantasy and imagination.

My setup

Source:
Audiolab 8000CDM Transport + Bel Canto DAC2 (24/192 upsampling – thanks, Jude!)

Reference amps:
Brocksieper Earmax Pro
Corda Blue
direct path
(via 500 ohm potentiometer) from DAC line out

Interlink cables:
self-made, 0.028 mm magnet wire design, quasi-symmetric

Headphones:
Sennheiser HD 600 (thin nylon gauze instead of foam pad as driver protection), magnet wire cable
Etymotic ER-4X (own foam-tip and filter design, 67 ohm total impedance), low-microphonic Fixup cable
AKG K 501
Grado SR-225 and SR-325 (both with trimmed flat Sennheiser pads), shortened stock cables
Sony MDR-F1

One note to my cable philosophy

I like to do handicrafts – rather in the actual sense of the word –, and that's how most of my self-made cables do look like. But I don't care that much about looks. I have experimented with a lot of different materials and geometries – purely empirically, without any theoretical basis – and have thus found the trace to some sonic tendencies and their causes. The greatest purity of sound and accuracy I've finally found with as thin as possible separately lacquer-isolated copper wires («magnet wires»), bundled to strands of several hundreds. It seems likely to me that the skin effect is responsible for the perceived extended and smooth upper end. Besides: with normal cables, there are similar single wires, but they're not isolated from each other, so the current (the electrons) occasionally jumps from one to another. Intuitively I suppose this could be the cause for the somewhat rough sound of most of the corresponding designs. Like all cables they're not completely neutral. I would rate their characteristic somewhere close to the tube sound – they represent my ideal of a liquid, grain-free, ultratransparent sound, at the expense of a tiny bit of coolishness and sleekness (well, really just a trace).

One note to my direct-path philosophy

The unbroken current path provided by magnet wires can be seen in proximity to a system that renounces all unnecessary components. Like with my speaker setup, where there's no pre-amp stage, just a passive attenuator, I use a simple 500 ohm potentiometer connected between the DAC line out and the headphones instead of a dedicated amp as a sonic reference. I suppose that's how the source really sounds. Electrically, it creates an effective serial resistance to the headphone not exceeding 120 ohm and even less than zero values at minimum and maximum volume settings. Within the usable range it's around the 100 ohm mark.

Headamp-2 details



I renounce a detailed listing of its properties – you can see all relevant things from the descriptions at Meier-Audio.
The most important external difference to the HA-1 are the ¼" jacks and the now only two crossfeed positions, switchable by a small lever in the lower middle of the now thicker frontplate on which the red LED is banished to the extreme left. Pity the red light sits in a hole – from a certain not too big angle you see nothing but a diffuse red sheen.

As mentioned in the user manual, the crossfeed symbols on the front plate are erroneously engraved the wrong way. Instead of the pretended order stereo / crossfeed 1 / crossfeed 2 the circuit is in fact switched this way: crossfeed 1 / stereo / crossfeed 2. Just a tiny blemish...


The sound

In the beginning I was listening almost exclusively with my modded HD 600, the most reveiling of my headphones, to my ears, not to bring too many variables into play. As already mentioned, the sound has made huge changes during the burn-in process. Even now, after maybe 50 hours of operation, I'm not sure if and how it will develop further. The last ten hours have brought a further progress – I think a decisive one. That's why I think I can risk to begin with this review.

At the very beginning it sounded soft, bright, sleek, undetailed, technical, artificial, 2-dimensional, uninspiring, boring and soft (again). Well, surely the sound was smooth, anyway. But I didn't like it at all. Comparing it to my reference, the direct path, there was a huge difference in dynamic contrast, clarity, soundstage and transparency. After two hours the detailedness was somewhat increased, and so was the transparency, but still there was that omnipresent brightness (though not shrillness) which extremely reduced dynamic contrast and bleached sonic colors. After five hours a considerable change was made: much more details, now even downright opulent and at the expense of transparency. But still that brightness and those soft highs... dynamic contrast a little better. Still not much fun with rock, but strings were amazing, lifelike, with brilliant brass highlights. Better soundstage. But it changed to the worse again: the overwhelming detailedness corrupted the transparency, the sound became harsh and dry. The brightness was gone more or less, but still dynamic contrast was limited, though finally noticeable.

There were a lot of stages afterwards, most of them seemed to change rather abruptly. But it wouldn't make much sense to list them, I'd just like to mention: it was a hard time... And that's the situation now, after 60 hours of operation:

Very accurate bass, not pronounced, but strong and deep. Ultimate midrange details and transparency. Very detailed, smooth, ultra-fast and hyper-delicate treble. One could almost call the sound analytical. There's so much detail. But there's also that smoothness that makes the music flow, not just seem to be composed of details. And there's that 3-dimensionality. What a soundstage! I tried all listed headphones, and with all of them the two main sonic signatures are clearly shown: the highly resolving midrange and the incredible smoothness. The HA-2 ties in with the Corda family character: already the HA-1 had that typical crystal-clear midrange from which the sound seems to emerge. The HA-2 can be seen as a refined HA-1.

«4 Concertos» from Marius Constant (Erato 2292-45527-2), one of the best classical recordings I own (the musical content is of high quality as well) – it could just as well be called «jazz», it's both contemporary classical and jazz –, shows the HA-2's strengths extremely well: detailedness, speed and smoothness. From a silky-smooth strings carpet arise some aggressive brass tones in a sheer breathtaking sharpness and clarity. I can see the shaded concert hall and the sparkling brass instruments on the orchestral stage. The cymbals are also extremely well recorded: there are four different types, hit alternatingly in short intervals, and each of it is clearly distinguishable. They sparkle and shine in the spotlights as if there were no CD low-pass filter in the signal path. This sound has a hypnotic touch.

What's always interesting me most is how the sound of an amp compares to the direct path, thus the supposed original sound. It's no surprise: it's not exactly the same. The direct sound is more airy, more «tubey», somehow fresher and not of that noble smoothness as with the HA-2. As if there was more light on the stage. Cymbals are smoother, a bit less sharp, but at least equally lifelike, while the strings' slightly coolish liquidity seems to be a bit less appropriate than the HA-2's silky-smoothness. I'm tempted to describe the latter's reproduction of cymbals as if they were of pure, sleek gold, while the direct path's cymbals are of the original brass. From the Corda Blue, they sound a bit like of mat aluminum in comparison. Anyhow I like the latter's a trace dark and breathy coloration, although it doesn't exactly match the live impression the direct path and the HA-2 are capable of providing.

Interestingly the HA-2 sometimes sounds brighter and sometimes darker than the direct path, but rarely equally balanced. Its smooth highs and a slightly leaner bass compared to the direct path occasionally lead to the impression of a midrange emphasis. At the latest when I switch to the Earmax Pro. The latter's greater airiness, which it shares with the direct path, makes the HA-2 sound like a solid-state amp somehow. While their soundstages are of equal extension, the HA-2's spatial focus is sharper, but the EMP's orchestra seems to be of a bigger size. Anyway, this is a matter of taste and no real downside for the HA-2.

The HA-2 has an outstandingly lifelike presentation of great purity, unless the EMP comes into play, making it seem slightly colored. Which it is, objectively, if I take the direct path as a benchmark. The EMP sounds much more similar to the direct path, just enhancing liquidity and airiness to a degree which leave its credibility and naturalness intact. In fact it is the amp which seems to sound most natural of all alternatives I have at the disposal, including the direct path itself – except for the reproduction of a string orchestra, which the HA-2 performs simply magically well. And it does a lot of other things well, subjectively, without having to turn a blind eye.

I left the amp off for one night – the first time since I got it. I wondered if there would be a new warm-up phase. This wasn't the case. I think the sound has definitely consolidated now. And its main sonic signature is clearly audible: the similarity to the HA-1. Well, the increase of detail and resolution is unignorable, and so is the absolute absence of any grain. It's smooth from the bottom to the top... pristine, as kelly described his PreHead. But there's also that slight midrange emphasis – creating an impression of immense clarity and transparency –, followed by a somewhat underrepresented lower treble range. That's what increases the image of smoothness and nobleness, to a certain degree at the expense of airiness and a tendency towards sharpness with certain treble-friendly recordings, due to the thus exposed and pronounced upper treble.

On a sampler CD with the «Theme from Pink Panther» (from «The Very Best Of», Telarc 80401), a fantastic recording in terms of instrument timbres, resolution and soundstage, the HA-2 offers all of its strengths. Its resolving ability is spectacular. «Advent» (from the CD «Cantate Domino», ZOUNDS Gold 2700033006) shows more of it: the very dense sounds of a mixed choir with organ accompaniment. The HA-2's presentation reaches the direct path's purity and resolution with ease. But the latter sounds more organic – the singers' breath is more articulate. That's one of the strengths of the Corda Blue: it even cultivates this element with its slightly breathing timbre, at the expense of a bit of smoothness and the ultimate resolution. But it sounds clearly more organic, too, in comparison to the HA-2. Nevertheless, the toss goes to the HA-2 because of its downright spectacular resolution and the sense of space it provides.

This recording shows a downside of the Earmax Pro: the multiple harmonics in this music, especially the singer's breaths, are slightly smoothed, slightly smeared by an enhanced liquidity; but over-all the sound is equally organic, with quite accurate timbres, as the direct path's presentation, and the resolution, though not quite equally spectacular, is equal to the HA-2's.

Frank Martin: «Petite Symphonie Concertante» (Erato 2292-45694-2). Here the harpsichord sounds a bit synthetic with the HA-2, a bit on the tinny side, while direct path and EMP sound outstandingly lifelike, with wonderfully reproduced instrument timbres. Nevertheless, the recording is very pleasing and has its charm with the HA-2, with its plenty of details. «Ballade for piano and orchestra» (Chandos 9380) from the same (Swiss) composer: wow! The direct path sounds great, barely exceedable – but what about the HA-2? Its presentation was stunning! Such a credible, atmospheric, flowing sound, incredibly transparent up to the excess, but without being analytical at all! The piano sounds very clear, but not bright or tinny, but with a fine and robust body, although not dark on the other hand. It's not quite the original sound, obviously, but it's very credible anyway. It's refined reality.

Want some rock? U2's «Achtung Baby», «Zoo Station»: I was captured from the first note on. «Even better than the real thing» – a good description of the HA-2's sound: I just didn't want to switch to the other amps anymore... let it rock! The sharpness from the ultra-detailed and -fast treble goes in a certain measure to the account of the foamless HD 600, but I simply don't care: I don't want it any other way: it's just fun! Who says the HD 600 is veiled! It's a rock can! I turned crossfeed on, both 1 and 2, and I liked it with «Zoo Station», where the guitar intro is extremely left-sided, but for comparability reasons I finally left it off. Man, I like this amp! Switching to the direct path, it seemed as if the sound was more neutral, the same with the EMP, which BTW is fine with rock. But the detail and speed from the HA-2 made me a slave to it with this CD. And so with lots of other rock CDs.

I mentioned the HA-2's slightly leaner bass compared with direct path and EMP. It's not really an issue. It's obviously a result of its low output impedance. And it's «fixed» by some 60 ohm serial resistors in an impovisedly made adaptor. The 120 ohm output on the other hand created a bit too much bass. But other than for comparability reasons I didn't use this adapter, in fact it wasn't necessary: the HA-2 has really enough bass. And the sound turned slightly to the worse with it: less detailed, less natural. Nevertheless: the Corda Blue is the bass king in my collection... and this with equally low output impedance...

Summary

The HA-2 is not what I expected. I thought it would be a Blue with extended and more liquid treble. But it has turned out as a refined HA-1. Am I unhappy? Not at all! I'm even enthusiastic about it. It has such a hypnotic sound which makes it hard to part from my headphone once I put it on. It's ultra-smooth, ultra-clean, ultra-detailed and ultra-transparent. That's a bit of a dangerous mixture. The downside: it can sound synthetical sometimes. Astonishingly it suits rock, jazz and classical equally well, except for some critical recordings where the timbres of instruments suffer a bit from the HA-2's transfiguring character. While others even benefit from it.

Are tube amps euphonic at last? I think they are, as shown by the EMP. But the same applies in the same degree to solid-state amps, if I'm allowed to draw such a conclusion from the handful of (headphone and speaker) amps I've already heard. But why do I not simply settle for the direct path? It's easy to explain: it sounds a bit more attractive with my best amps. And the HA-2 is definitely one of them. Currently my favorite one – of course due to the novelty effect, but maybe more than that.

Beside the HD 600 which has been my main instrument throughout the whole auditioning, I tested several other headphones, how they match with the HA-2. The Etymotic ER-4 is by nature (to my ears) not extremely critical in terms of amps. Nevertheless it shows all the mentioned characteristics the HD 600 has revealed. I like it with the HA-2, but I slightly prefer the direct path and the EMP because of their more natural reproduction and the smoother (less sharp) treble. For both Grados the HA-2 is the best match behind the EMP; for rock the HA-2 is first choice. Highly recommendable! The AKG K 501 matches best with the direct path and with the HA-2, whereby the latter provides the greater fascination and sounds warmer (!). Finally the Sony MDR-F1: EMP and direct path are in front, while with the HA-1 the F1's midrange emphasis is slightly pronounced; nevertheless not a too bad match. (All these ratings are supposed to mean «to my ears.»)


Ooommph!!! It was a hard way to get there! Somehow I feel as though it were due to my own merit... But of course its very much the merit of the team around Jan Meier, which has created such a wonderful piece of technics. I hope you enjoy my review and it's helpful if you're interested in an amp upgrade.


JaZZ
post #2 of 51
Jazz,
Thanks for the review and for taking a little time to collect your thoughts. Hope you have better luck with this thread. I have a few things that I didn't understand, maybe you can explain:
Quote:
the overwhelming detailedness corrupted the transparency,
Quote:
much more details, now even downright opulent and at the expense of transparency.
To me, an inherent quality of what I call "transparency" is the ability to reveal additional details/musical information. Isn't it a contradiction to call something so detailed, it's not transparent?
Quote:
But still that brightness and those soft highs
Again, to me "bright" and "soft" do not apply to the same phenomenon. If it's "bright" it's likely to be piercing and shrill, not "soft", yes? Not clear to me here what you are trying to say. Cheers.

Mark
post #3 of 51
Very nice review!
post #4 of 51
Thread Starter 
Quote:
Originally posted by markl
To me, an inherent quality of what I call "transparency" is the ability to reveal additional details/musical information. Isn't it a contradiction to call something so detailed, it's not transparent?
You're right, that seems to be contradictory. Intuitively I thought it would be understandable anyway. There were overwhelming details adjoining without air in between, all in the same layer, without leaving the sight into any depth, giving the impression of seeing through something, and lacking liquidity.
Quote:
Again, to me "bright" and "soft" do not apply to the same phenomenon. If it's "bright" it's likely to be piercing and shrill, not "soft", yes?
Imagine a frequency response slightly increasing to higher frequencies, but rolling off at a certain point, say 10 kHz; something like that was my impression then.

Anyway, that's not up-to-date anymore: that was during a certain stage of the burn-in process. Now the sound is completely different. – Thanks for asking and the opportunity to clear up!

JaZZ
post #5 of 51
Great review. I can't wait to get mine.
post #6 of 51
Excellent review. I entered it wondering how the HA-2 compared to my Corda Blue. You ably answered that, and many other questions as well.
post #7 of 51
very informative review JaZZ! thank you.

you wrote that "One could almost call the sound analytical." and "The downside: it can sound synthetical sometimes".
Do you still feel the HA-2 to be an analyical amp, enough to distract you from the music? thus do you found yourself wanting to tame it down, perhaps with IC or gone with another opamp?
post #8 of 51
Thread Starter 
Hi taoster!

The analytical aspect has only to do with the extremely detailed highs. The sound as an entity does not seduce to concentrate on details, its quite the opposite: the lush, slightly dark midrange and the recessed lower treble make the music flow and have a downright hypnotical effect. There's no other amp which makes me capture that much from the music without having to nitpick about the sound, which simply is how it is: extremely envolving. That said, I have to concede that it's not neutral. The mids are too dark and the highs are too bright. It can sound sharp and synthetic indeed. The timbres of instruments are slightly colored, sometimes to their benefit, like orchestral music where the string orchestra's silky-smoothness and the brass' metallic sharpness are emphasized.

Once you hear it, it's hard to settle for the somewhat more «normal»/neutral presentation of the direct path sound (and the one from the EMP, too). I would say its «hyper-realistic», better than reality. I wouldn't want to modify it with some cable tweaking at the moment, not to lose its magic. For normal use I already have other alternatives... I have not a great experience with (buyable) cables, BTW; I guess it should be possible to tame the upper end, but it's also very well possible that the sound would not benefit from this. It would be interesting on the other hand to hear the other op-amp variant. I wonder if it has more of the Corda Blue signature, I guess it has. Something between the HA-2 and the Blue with the full HA-2 resolution would be attractive; well, possibly it would just sound «normal». Maybe Jude could tell you about his experience with his PreHead with that other op amp.

JaZZ
post #9 of 51
Nice review JaZZ, thanks!
post #10 of 51
Jazz:

Thanks for the great review...I want one!
post #11 of 51
Quote:
Originally posted by kpfeifle
Jazz:

Thanks for the great review...I want one!
Hey! isnt that(your avatar) an aussie wombat!! or is that what a rat from NY look like.
post #12 of 51
Quote:
Hey! isnt that(your avatar) an aussie wombat!! or is that what a rat from NY look like.
Very OT, but it is an Aussie Wombat.
post #13 of 51
Hi JaZZ,

I like what youve found about the HA-2, its exactly what I am hoping for. I bet you'd be hard pressed to found any amp to match the HA-2's detail and speed. My only concern is if it may be shrilly, tinny and bright, while great for instrumentals but unnatural for vocals. i cant imagine what it would sound like being both detailed and lush. Jan's taste is more on the bright, analytical side so it was good to hear comparisons to the EMP.

the other thing ive been wondering, how did you hook the system up to the source? are they sharing the same source, Bel Canto DAC2? or did you swap the component in and out. using anything like the vampire rca spitters?

when the time gets closer to purchase, ill drop Jude a pm. that's if he hasnt replied on the forum already. Jude?
post #14 of 51
Thread Starter 
Status report

After maybe 75 hours of operation (20 hours since last report)

Sorry to say: a great deal of the lushness is gone! The good news: there's no midrange emphasis anymore. Instead the perceived lower treble dip has filled up – suddenly there's much more air. Voices and instrument timbres are clearly more natural. There's also a trace hardness now (I'm rather sure this will go away with time after all) and less liquidity, but even more detail than before. What impresses me second most: the soundstage seems to have further expanded, the orchestra is larger and most notably the spatial focus is sharper than ever. But the biggest jump has made the bass. It's on Corda Blue level now, and it's even tighter, cleaner and deeper. Sorry for the psychic stress – I have it myself too. But it's also fun. Especially that bass.

Quote:
Originally posted by taoster
...how did you hook the system up to the source? are they sharing the same source, Bel Canto DAC2? or did you swap the component in and out. using anything like the vampire rca spitters?
Yes, I'm using RCA spltters, the first one right on the DAC out, and there are two amps and the direct path connected each time; occasionally I'm swapping between the EMP and the Corda Blue.

JaZZ
post #15 of 51

The cameleon...

Jazz,

I am quite amazed by your comments. Particularly about how much cameleon-like the HA-2 is over the first 100 hours of use. I own the PreHead which, following Jan's comment, is almost identical sounding. I did notice the brightness and unnatural highs going away after quite a few hours (although I burned in my HD600 at the same time, so which is which?!). But man, you're describing it to a whole new level!

In any case, although my listening might be more relaxed / less picky than yours, I can guarantee you this amp, when settled in (300 hours?), is not a cold chirurgical/analytical beast!!! I have it hooked up on a Meridian source and stock HD600. Jazz, classical, (good) rock, and even electronic (Bjork) recordings sound everything but cold, not tiring at all! On the contrary, you CANNOT stop listening. The voice is something I am very sensitive to, and I find it personnally very very very natural.

In the end, I personnally believe this amp will rather reveal the character of the other components. If it's bright or thin, it must be somewhere else, no?

Arnaud.
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