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Bakoon HPA-21 headphone amplifier - Page 21

post #301 of 589
Surely it's inevitable that the HPA-01 will have inferior (however marginal) sonics to the HPA-21, otherwise why would anyone pay the extra price premium to acquire the latter headphone amplifier?

Originally Posted by bmichels View Post

Agree.  I just hope that there will not be "significant" reduction in SQ !    
The HPA-21 is praised for its incredible SQ, and we want ....the same with HPA-01  :-) (at least with dynamics and "easy to drive" planars").  

So if it is just "less power" that is fine, but id it is less SQ/Soundstage...  NO NO !
post #302 of 589
Thread Starter 

I compared HPA-01 and HPA-21 at the show but I cannot tell you how they differ in sound since different DACs were used. HPA-21 used a Lindemann USB DAC while HPA-01 used an Auralic ARK MX+ (I think). Lindemann --> HPA-21 --> SW --> LCD-X produced the sound I'm used to. Auralic --> HPA-01 --> SW --> LCD-X sounded a little bit softer with less treble extension, but I believe this is due to the different characteristics of the DACs since these amps are so transparent. I recognized the "smooth" clean sound from HPA-21 though. HPA-01 has no problems whatsoever to drive LCD-X.

post #303 of 589
Thread Starter 
Originally Posted by ariesq View Post

Anyone try the LCD-XC with the HPA-21? The LCD-XC is a little on the brighter side compared to LCD-X, just wanted to see if they had the same synergy that other's are reporting.




Since it was the first time I heard LCD-XC I compared LCD-X and LCD-XC using HPA-21 (current output of course).

From all the comments in the LCD-XC thread my first reaction was that LCD-XC is less similar to LCD-X than I thought.

You have to turn up th volume a little bit for LCD-XC to get the same SPL as LCD-X.

LCD-XC has a hump in the frequency response in the high mids / low treble that for example makes voices sound more trebly, "in your face" or more close miked if you will. When you switch back to LCD-X the voices turns notably softer.

The bass is a little bit stronger than for LCD-X.

I didn't think of any differences in the treble.

LCD-XC has a little bit less airy and more "compact" or "solid" sound than LCD-X, as expected of a closed can.

post #304 of 589
Thread Starter 

I also tested AKG K812 with HPA-21. I became a little bit in love with K812 actually, it is like a contrast to Audeze. The treble is a little bit too hot to be neutral, but that's OK. The bass is clean but misses the impact of planars. It turns out the impedance curve is relatively flat with a wide hump around 100 Hz, thus it is eq'd in the same way using the current output of HPA-21. This probably makes a somewhat bassier and softer sound compared to a normal voltage drive amp.


However when I saw the measurements I was put off. Significant ringing, lots of distorsion, polarity inversion. And you can't use a balanced cable with them either since the connection is one mini 3-pole XLR. They are a little bit too small for my big head also. What I love with the Audeze and HD800 sound is the "exactness", which I think is the result of low ringing and low distorsion, in other words a well behaved transducer. I would probably get tired of the K812 sound pretty soon.

post #305 of 589

I always been curious about the K812 pairing with the Bakoon so thanks Candude. ;)

But like you I came across those measurements and got frightened.

I also tried the LCDs on the Bakoon and they sounded superb  but I clearly preferred the LCD3 over the X. I have to say I am not a fan of the Audeze sound but since hearing those on the Bakoon I have considered getting the LCD3. But with some many new headphones coming out  this year I am going to hold off for a while.

post #306 of 589
Anyone can tell the differences of LCD3 being drive under high gain or low gain (current mode) of HPA-21?? I tried it many times but seems my ear is not sensitive enough to find out the difference... :P

The only differences I heard is the high gain has stronger back ground music and stronger instrument separation, while the low gain has better vocal voice. Anyone any ideas about this? biggrin.gif
post #307 of 589

another "current mode" headphone amp ?  I thought that this mode was unique to BAKOON ??


post #308 of 589
post #309 of 589

Quite different topology in fact. The Bakoon as far as I know is the only "real" current headphone amplifier. The only outputs on the Questyle is actually voltage driven and seem to pair extremely well with high impedence cans such as HD800, while I found the opposite true for the Bakoon.

post #310 of 589
Originally Posted by zenpunk View Post

The Bakoon as far as I know is the only "real" current headphone amplifier.



post #311 of 589

Interesting but something must have been lost in translation as after checking their website and skimming through the 6Moon review it doesn't look like those are current amplifier at all or am I missing something? 

post #312 of 589



From the comments:

Regarding output... it is a bit tricky to say what exactly it is. Yes, it is a current buffer, but it adapts to the load, so it doesn't work in a classic way. For example, if you put on 10 ohm headphones or 600 ohm headphones they will have same power on them (around 150 mW/channel), not 60 times different power.

Although 6moons reviewer from Poland is a cool guy (I met him personally), I find his review at some parts confusing, too. Anyway, there will be another review online soon, so we'll be able to hear a different perspective.


Would you be willing to let us know what the output device is? What is the output impedance? Sorry about all this confusion. 


In Bacilluses it is Burr-Brown's BUF634T set to maximum speed. In Perfidus it's a class-A transistor based amplifier. Output impedance is about 56 ohm, but don't be alarmed about it, because it works in a bit different regime.


As I mentioned in a post above, a current drive amp is indeed a different kind of beast, and output impedance doesn't matter at all in the way it does with a voltage drive amp. Really looking forward to the chance to hear one of these amps. Keep up the good work!


I must admit that I don't know enough about amplifier designs, but it seems that the Erzetich amps are also current drive amps like the HPA-21.

post #313 of 589

All I could gather is that it uses an amp buffer after a voltage gain but that doesn't really make it a real current source in my book. Current source have extremelly high output impedence such as 2.5Mega Ohms in the case of the Bakoon.

The Erzetich products are propably more similar to the Questyle. Still, interesting design.

Edited by zenpunk - 2/18/14 at 11:43pm
post #314 of 589
Any more news about the HPA-01 ?
Did someone else heard the prototype unit at the show ?
Availability ?
post #315 of 589
Originally Posted by bmichels View Post

Any more news about the HPA-01 ?
Did someone else heard the prototype unit at the show ?
Availability ?

I was reading a 6moons review, on the Metrum Aurix I believe, and he mentioned it as being 2.000 euros. A typo perhaps, but I've got a feeling that slip means the guy there probably has one in for review.
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