[kelly]

arnaud
As far as the Prehead goes, I'm in full agreement with you. I mostly left my Prehead on unattended and didn't do much ABing until it had a lot of burn in--I wonder if the Prehead went through the same changes as the HA-2.

JaZZ
I have to say this is one of the most interesting review threads I have read. Thanks for taking the time to do the comparisons and post your comments.

 

[JaZZ]

Actually I'd better shut my mouth now.

But possibly you are interested how the evolution is going on...

The hardness is gone to a great degree, and the magic is back. Smooth mids again, the latent sharpness in the upper end obviously is undividable part of the sonic signature and perhaps even the trick to hypnotize the listener – balanced by and in cooperation with rather dark mids and now a very strong and deep bass. Thus the sound has become very organic. It's not more natural anyway, it's rather supernatural... Great musicality. Euphonic by all means. Every detail, every transient is delicately and deliciously overemphasized. In a way that has nothing to do with analytic sound (I agree with you, Arnaud), which would stay on the surface. This sound reaches deep; it is highly emotionally envolving and of a touching beauty. And highly dynamic at the same time. Nevertheless I stand by my words: it's not quite natural or neutral, respectively. But I love it.


kelly...
...thanks for your visit and your appreciation!

Quote:

Originally posted by taoster 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.

Yes, that's indeed the case: it's both extremely detailed and lush. And in no way bright, but exceptionally expressive with voices. BTW, I wouldn't like to counter your bet...

Quote:

Originally posted by arnaud 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?

Maybe you forget that my reference is the original sound from the DAC, and all my «complaints» refer to the deviation from it – while your belief is based solely on your love for your amp...

In case you doubt that the signal from the DAC's output can drive a headphone adequately, here some specifications:

It may seem as if the amplifier stage in the DAC ouput was a bit weak to be used as a headphone amp. On the other hand, it is designed to drive full level up to digital zero (2 volt in the case of my DAC2). You may be sceptic about its ability to work on low impedances (normal line level input impedances are around 30 kOhm). My DAC2 has an output impedance of 20 ohm nominal. Electrically it should be fine for all impedances above say 20 or 30 ohm. The one it has to do with here is between 200 and 500 ohm.

So far, so good. If this impedance is an issue, it will be shown with the amps running in parallel to the potentiometer. In fact there's no alteration of sound with or without the potentiometer hooked up when listening music through any of the amps, even when there's a headphone hooked up on it to test if there's any reactive electromagnetic induction from its voice coils.

When I use my AKG K 501, it's easy to find a moderate-level passage on any CD to turn the volume to the max. This means absolute no resistance in the signal path (this in case you base your doubt on impedance matching), but the sound character is unaltered to the one with any other volume setting; a tiny bass enhancement in the latter case is negligible.

All in all this is a strong chain of pieces of circumstantial evidence to prove that the direct path system effectively provides an unaltered reproduction of the source signal. BTW, given that there are considerable sonic differences between different amps it is no surprise that their corruption of the original sound is at least of a similar degree – save you suppose there's any über-amp and maybe the HA-2 just is it...

JaZZ

 

[Suedama]

JaZZ:

I concur with some of what you have said about the HA2. Initially, I thought the bass was somewhat understated, but after about 25 hours I can say that it become very full and rich. Also, there was a distinct improvement in the sound stage.

Most of the other stuff you said I frankly don't understand so I will not comment on it. (The lushness was there? Then it disappeared completely? Now it's back in all its glory? Hmmm. I didn't notice anything like that, at least so far.)

You're pretty analytical, Jazz. Maybe more analytical than your amp.

 

[arnaud]

Jazz,

This is quite interesting that you have a DAQ that can properly drive headphones. Is that something common or your particular piece of equipment that does the job nicely?

If this amp is indeed not neutral, then it should obviously not marry well with some headphones right? Are you still mainly using the HD600 or swaping around? I personnally had a quite bad experience with the PreHead / Grado RS-2 combo. I blamed it all on the Grado (up to the point of selling it actually), but you might be saying that the sonic signature of the amp might be a cause?

Humm, you are bringing quite interesting points here. Please keep going until it all settles!

Arnaud.

 

[glasskangaroo]

JaZZ,

I can't begin thank you for your incredibly generous and richly detailed review of the HA-2. You single-handedly addressed all of my questions, hopes and concerns in one fell swoop. I'll be ordering mine within a few months, a decision expedited all thanks to you. If you're up to it, please keep the HA-2 insights coming. They'll always be read with great interest. Although I can't thank you enough, thanks JaZZ!

Sending you a virtual pat on the back via cyberspace - glasskangaroo

 

[JaZZ]

Suedama...

...lucky you! Full development of sound after only 25 hours! How did you manage that?

If I compare this with all the stages I had to go through... yes, all these things have happened (the resurrected lushness) indeed.
Quote:

You're pretty analytical, Jazz. Maybe more analytical than your amp.

Very true! I thought that's the best way to offer an as neutral as possible image. BTW it's a bit my nature, too. Maybe kind of overwhelming detail lacking transparency?

Arnaud...

Quote:

This is quite interesting that you have a DAC that can properly drive headphones. Is that something common or your particular piece of equipment that does the job nicely?

...that's nothing special – and 2 volt is even at the lower end of the common signal level. The only issue is the output impedance, it should not exceed a certain value, which I can't define exactly (not more than 100 ohm?). And this is something I'm not sure of: which is the average output impedance of common CD players? My Theta DAC has 6 ohm (and 5 or 6 volt!), my Bel Canto 20 ohm (2 volt), and both are equally suitable, save the Theta has more loudness reserve, e.g. providing adequate level with low-level passages listening with an AKG K 501.
Quote:

If this amp is indeed not neutral, then it should obviously not marry well with some headphones right? Are you still mainly using the HD600 or swapping around? I personally had a quite bad experience with the PreHead / Grado RS-2 combo. I blamed it all on the Grado (up to the point of selling it actually), but you might be saying that the sonic signature of the amp might be a cause?

Yes, definitely. Or rather: the synergy between it and the headphone. I know the RS-2 only from reviews and descriptions, but know the similar but brighter SR-325. As it seems to have a lush and warm signature, I can very well imagine how it mismatches with the HA-2, which could emphasize it to the excess at the expense of balance, transparency and detail. – Yes, I'm mainly using the HD 600 for audition. It's a very reveiling instrument, ideal for this purpose.


glasskangaroo...

...I'm very glad it's useful to you. That was my main intention: to give as much, detailed and analytic information as possible in a way to enable the reader to draw his/her own conclusion how this amp would possibly sound in his/her own setup.


I'm a bit in doubt, too. Probably there are not many others who share my obsession in the search for the true sound. My direct-path reference could be misleading. I wanted both: do justice to the amp and the merits of Jan Meier on the one hand and give as neutral as possible information on the other. I don't know if I have succeeded. I like the HA-2 a lot, though it fails on the default of the direct path – which is simply impossible to reach: each amp has its own signature, it's obviously and logically impossible to get an absolute neutral sound from an amplifier, and nobody ever pretended this, as far as I know.

Current status

: the sharpness is no issue anymore.

JaZZ

 

[taoster]

Quote:

Originally posted by JaZZ I'm a bit in doubt, too. Probably there are not many others who share my obsession in the search for the true sound. My direct-path reference could be misleading. I wanted both: do justice to the amp and the merits of Jan Meier on the one hand and give as neutral as possible information on the other. I don't know if I have succeeded. I like the HA-2 a lot, though it fails on the default of the direct path – which is simply impossible to reach: each amp has its own signature, it's obviously and logically impossible to get an absolute neutral sound from an amplifier, and nobody ever pretended this, as far as I know. Current status : the sharpness is no issue anymore. JaZZ

I am not altogether convinced that the minimalistic approach would produce the truer sound for headphones. Besides the issue of impedance mismatch. I am still a little suspicious whether a DAC can drive headphones accurately. If a 9V can drive my Porta Corda well, a 24V can drive it even better and truer. Could it be possible an amp allow for the phones to reach its truer potential easier than a direct-path? and direct-path is not as true as it seems? On occassions Ive plugged my phones directly into a USB computer audio out device, the lack of power fails to drive the phones accurately.

 

[Howie]

Hey JaZZ I am even more eager to have my amp arrive after your review.

Have you tried the amp with a lesser source? Eg. PCDP? Since you talk about the amp being very detailed and I assume that means revealing. How forgiving is it to bad sources? Have you tried it wit poorly recorded music?

 

[KurtW]

JaZZ, thanks for your very detailed report, I found it very interesting.

To drive headphones you need both enough current and voltage. Since most DACs (and preamp outputs) are designed to drive high impedance loads, they don't need to provide much current but can deliver a fair amount of voltage into a high impedance load. So as long as the headphone's requirements are within the DAC's capabilities you can drive them. If the headphone's requirements are taxing the DAC's capabilities, its quite possible that a headphone amp will do better job.

toaster, you're talking about supply voltage for the Porta Corda. With a 9v battery the Porta Corda cannot even deliver 1v RMS output into a 30 ohm load (or at least mine can't) but it can deliver much higher voltages using a higher voltage supply, and it can deliver much higher voltages into a higher impedance load with the same 9v power supply. BTW, for me even the 9v battery does fine job using 30 ohm headphones, so I guess I need less than 1v.

 

[Suedama]

Howie: Jazz can probably speak more authoritatively on this, but I think you will find the HA2 to be very revealing. One of my favorite recordings is "Horowitz in Moscow," (the historic return of Vladmir Horowitz to the land of his birth after decades of exile). It was recorded live, which right away creates problems for any recording. Unfortunately, I could hear every cough in the auditorium, every footstep of the idiot who was walking around during the concert and at one point even the breathing of someone who was close to one of the pickups. After a while, of course, your attention gets so distracted from all this detail that it is impossible to listen to the music.

On the other hand, the magnificent detail of Yo-Yo Ma's cello in Brahms: Sonatas for Cello and Piano (Yo-Yo Ma, Emanuel Ax) has just the opposite effect. It draws your attention right to the core of the music to the point that you feel like Yo-Yo Ma's $1 million Stradivarius is close enough to touch.

 

[JaZZ]

taoster...

...you'd like the HA-2, be it neutral or not. I for myself am convinced that what I hear with the direct path is more or less the unaltered original sound (which itself isn't neutral anyway; it's created by electronic circuits based on solid-state technics). The above mentioned test configurations show no obvious sonic influence from «impedance mismatching» both headphone- and DAC-output-stage-(power-)related. So do you really think a piece of wire is less neutral than any amplifier? Maybe that's wishful thinking.

Howie...

...yes I have – in the meantime. I have plugged in an MP3 and a MD player. With both the sound was great. I guess the HA-2 is revealing regarding the details on a recording, but at the same time forgiving with bad recordings and sources.


Hi Kurt!

You may be interested how «your» Corda Blue compares with the HA-2. Well, all in all it's topped. Anyway, the crown for the best bass goes to it: it's tighter and more impactful than the HA-2's. Dynamic is its great strength generally, but it doesn't reach the HA-2's resolution capabilities and soundstage.


Suedama...
Quote:

It draws your attention right to the core of the music...

...well said!


The roller-coaster ride is not quite finished yet. After the sharpness was gone the sound appeared a bit mat temporarily. Now it's getting more brilliant again, I think in a more healthy way. The bass has become very strong and deep in the meantime.

The midrange resolution is still fabulous. All in all I can say: this is the sound I've hoped for – solid-state sound at its best.

JaZZ

 

[taoster]

Quote:

Originally posted by JaZZ taoster... So do you really think a piece of wire is less neutral than any amplifier? Maybe that's wishful thinking.

It would be if the wires are very long

hey.. i dont think anyone ever asked this becz of jan's craftmanship but are there any warrenty on the units?

 

[Jan Meier]

Dear Headfellows,

I remember very well the first mail that was send by Jazz after receiving his amp. "Too bright, too harsh, ...."

I was shocked!

One hour later I received a second mail: "It sounds dull, no detail, ..."

I was stupified!

I'm glad everything turned well

Just a few notes:

It's normal that an amp changes it sonic character during the first 48hours. Every amp does. However, with most amps any slight component change that effects the signal path is normally barely noticed, as resolution of the amp is too "limited" for the listener to make this change realy audible.
By its concept the HA-2 has a very high resolution. That's why small changes are more easily heard and noted as seen through a magnifying glass. It's nothing to worry about and it's the mere nature of electronic parts (especially capacitors) that they need a decent burn-in to sound optimal.

For Jazz his reference is the direct output of his DAC. When the sound changes with the use of an amp, he claims that this is due to the sonic signature of the amp.
I must admit that I do not totally agree. There's a difference whether the output of the DAC has to drive a low impedance load or a high impedance load. Every output stage does change his character if the load is changed.
Moreover, the potentiometer in between output and headphone seriously effects the signal seen at the plug of the headphone. It slightly reduces high frequency response and boosts the lower frequencies (with a bump around 90 Hz). I'm convinced that the signal seen at the input of the headamp is NOT similar to the signal seen at the headphone plug if connected to the DAC (through the potentiometer). Due to the difference is connection conditions sound already will be different.
Whether the direct path is the better one or not I can't tell, as I haven't heard this specific setup. I do know though, that the HD600 has been explicitly designed to be driven by a headphone jack with a low output impedance. This has been told to me by the designer of the HD600 himself.

But at the end, theory is not important and the best path is the one we like most

Oh, and Toaster, all CORDA amps come with a 2 year warranty!

Cheers,

Jan

 

[JaZZ]

Hi Jan...

...of course I knew that an amp needs some time to burn in... I just didn't expect that the sonic changes be that extreme and the time to settle down so long... (BTW, it was never harsh, but awfully soft in the treble.)
Quote:

There's a difference whether the output of the DAC has to drive a low impedance load or a high impedance load. Every output stage does change his character if the load is changed.

As described in an earlier posting, I have paid special attention to this subject: listening through any of my amps and then switching the potentiometer with a headphone connected parallel to them, thus causing the said low impedance (around 200 ohm) for the DAC output stage, the sound didn't change. Such a load obviously doesn't affect its output signal.
Quote:

Moreover, the potentiometer in between output and headphone seriously effects the signal seen at the plug of the headphone.

Again, I have tested exactly this behavior by taking the potentiometer out of the signal path, using some low-level passage on a CD, thus providing very direct path conditions. I didn't notice any change, the direct path character was entirely conserved that way. I even didn't notice any leaner bass or brighter highs, though theoretically there has to be a certain effect. So the serial impedance doesn't alter the sound significantly.

On the other hand, when I switch any of my amps into the signal path, the sound significantly alters. And each amp has its very own sonic signature. It's hard to believe that one of them (which?) be absolutely neutral, or do you think so? Even if I concede that the direct-path system doesn't necessarily provide the ultimate, unaltered truth, it's much closer to it than any amp I can imagine. Again: just think of all the sonic differences among them!

BTW, it's not just the direct path which is my reference, but also my best other amps: Earmax Pro and Corda Blue. And most of all: the natural sound. So, in the beginning, and even with allegedly completed burn-in, I had the impression that the HA-2 was the least neutral of them – but it sounded great anyway. While the direct path, although obviously providing the most subtle details and by far the greatest transparency without exposing them, didn't sound most attractive. This is an experience I already made by renouncing the pre-amp for my speaker rig.

As to the HA-2 now: it has made a huge development. The last 20 hours have brought the lively and clear highs I have hoped for since the sharpness is gone. It sounds a lot more neutral now. It even comes close to the EMP in this regard, but sounds very different. I could say the sonic character of the direct path is exactly in the midde. The HA-2 is even beginning to sound most realistic to my ears. And at the moment it is the amp which is most fun to listen to. Congratulations on the HA-2, the finest (solid-state) amp I've ever heard.

JaZZ

 

[dhwilkin]

So how many hours does your Corda-2 have on it now, JaZZ? It'll be interesting to see when the changes stop happening...