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REVIEW: Amity HPA5A in comparison

post #1 of 5
Thread Starter 
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You've never heard of this headphone amp? I have received it taking the place of Head-Fi member muzikk who has bought it but was abroad at the moment -- and so had the opportunity to test it and compare it to my other two amps. (This review is the result of a special request expressed by Munzi [muzikk] and Manfred [lini] .)

Its developer is an American headphone freak named Anson Anderson, residing in Germany and building amps for his own enterprise, «Anderson Electronics» ( http://www.amity.de/index.html ). His HPA5X, the basic version of the test subject's follower model, has already been tested in the stereoplay magazine and been rated very good. One characteristic of this model is a distinct bass boost of up to almost 5 dB at 20 Hz with an angle frequency of around 400 Hz. In contrast, the HPA5A has a flat frequency response (fortunately!). I have asked V. Anderson (so his signature; I guess it's the developer himself) about the intention behind the bass boost, but after three answering mails I'm none the wiser... Nevertheless, the bass boost is reduced to 2 dB at 20 Hz with the new models, so that the frequency response is flat from 40 Hz to 200 kHz. The HPA5A has got higher gain and voltage than the basic model (HPA5) to drive the AKG K 1000; there's a corresponding jack on the front plate, whereas the normal headphone jack is banished to the back, between the two RCA input jacks -- with the left and right channel in reversed order. Another characteristic feature are the two separate volume knobs for left and right channel. But you can also order your amp with one stereo pot and just a standard headphone jack on the front plate (standard with the basic HPA5X) or additionally the AKG jack on the back plate. Also some variants with the electrical design are possible.

The HPA5A reviewed here is the predecessor of the current HPA5AX with its new board layout, but virtually the same circuit design and slightly different assembly.


Left: HPA4; right: HPA5(A)


Specifications

Input impedance: 42 kOhm (min.)
Output power/channel: 1 watt RMS (max.) @ 120 ohm
Channel separation: 98 dB
S/N ratio: 106 dB
Distortion @ 1 kHz: 0.004%
Frequency response: 10 Hz ... 50 kHz ±1% (!)

BTW, stereoplay has measured an output impedance with the successor model of «near 0 ohm».


Equipment used

Source: Philips DVD 963SA + Bel Canto DAC2
Amps: Corda HA-2, Earmax Pro (Siemens E81CC, 2x Telefunken E88CC), direct connection to DAC
Headphones: Sennheiser HD 650 and HD 600, Beyerdynamic DT 880, modified Etymotic ER-4P/X, Grado SR-225


Interconnects

Homegrown cables consisting of 0.028-mm magnet wires (~250-500 per conductor); also used for HD 600/650 replacement cable


Music

Giancarlo Trovesi Ottetto - Fugace
Viktor Ullmann - Symphony No.2
Mark Nodwell - Nemesis (SACD)
Archive - Londinium
Blondie - The Curse of Blondie
Kashmir - Zitilites



Sonic characterizations of the concerned amps:
(Most of the critical listening has happened with the highly resolving HD 650.)


Direct path

This is my point of reference. My DAC2 with its output impedance of only 20 ohm allows the connection of a headphone. The crucial point is the load impedance, since the typical loads are located in the thousands of ohms, whereas the HD 600 and 650 have 300, the DT 880 has 250 ohm. Tests have shown that the low load impedance doesn't affect the signal of the DAC2's line-out stage. So the direct path allows to virtually hear the pure source signal; there's only a voltage divider in the form of a 500-ohm potentiometer in the signal path, adding an effective serial resistance of around 70 ohm in the average, which is uncritical in view of the 250 and 300 ohm.

So if I'm trying to describe the sound of the direct path, I'm actually describing the sound of the DAC2 plus the concerned headphone. Nevertheless I have a certain image of the DAC2's sonic signature, which can be expressed as unvarnished purity, unfortunately with a slight, but noticeable technical or digital timbre (not substantially different than its predecessor, the Theta Pro basic II), manifesting itself in a slight coolness and sleekness of overtones. Keep in mind that we're talking about the CD format. (For SACD I have to use the 963SA's own line out with its 200 ohm, unsuitable for direct-path purposes.) Interestingly (but meanwhile no surprise anymore) the addition of a further amplification stage brings a considerable mitigation of this characteristic, at the expense of reduced transient speed and transparency. But transparency is one thing that can easily be sacrificed in this case, because there's almost too much in the direct-path mode, making it lack some of the warmth and naturalness an additional amp obviously sort of «reconstructs». Not that it's unlistenable -- far from being that! --, but the detour via a «good» sounding amp offers quite a bit more lifelikeness and emotion. I have given up to puzzle about this phenomenon, but (of course) uphold my conviction that the direct path represents the sonic truth within the concerned path source--headphone and thus a good point of reference for the judgement of the connected amps.


Brocksieper Earmax Pro

Its sonic signature is closest to the direct-path sound to my ears. There is some «syrupy» timbre involved, but very subtly so, just sort of filling the «emptiness» within the very transparent source sound. I guess a lot of people auditioning tube gear aren't aware that the original sound already comprises a lot of this kind of liquidity that gives the music this floating characteristic. Despite the somewhat reduced transient speed the treble is brilliant, slightly accentuated and gives the impression of a wide extension (well, in fact the bandwidth extends up to 1 MHz) and lots of detail. The bass is deep, full, strong and fairly well controlled. The midrange isn't emphasized at all (in contrast to what one may expect from tube amps), but well integrated, with very good detail. It's the range where the only significant weakness appears the most though: a slight lack of attack compared to the direct path and the other solid-state amps, but actually only evident in direct comparison. The EMP sounds great with simply everything and fits symphonic or chamber music -- with its careful treatment of instrument timbres and nuances -- equally well as rock and electronica with its richness of overtones, a real domain of the EMP. The soundstage is impressive, it's wide and deep at the same time. This is a very ear-friendly, beautiful and at the same time natural sounding amp with a great sense of air and space as well as excellent smoothness and resolution.


Corda Headamp-2

This amp has really grown on me a lot -- after causing some trouble in its break-in phase (see an early review). I doesn't captivate so immediately like the EMP, and after switching from the latter the sound appears as slightly artificial and lacking transparency, but only very briefly so. This amp is not a dazzler, but offers a deep insight into the music and all its beauty. The bass is full sounding, extended, controlled; there seems to be a trace of an emphasis in the lower mids and another one in the lower treble, making the outstandingly detailed and transparent midrange appear warm, whereas the treble is rather on the coolish side, with somewhat less pronounced detail and slightly rounded upper end, but nevertheless giving the impression of great clarity and purity of sound. I found a special synergy with grand piano: attack, fullness, sustain... it's reproduced with outstanding realism. The same applies to classical orchestra, especially strings. The soundstage appears less wide than with the other amps, but extended in the depth. This is a very refined sounding amp with a not absolutely neutral sonic balance, but ideally meeting the spirit of classical music and jazz, whereas rock and electronica are reproduced with energy and atmosphere -- over-all an almost sacral experience.


Amity HPA5A

It's easy to fall in love with the Amity. This amp has punch, warm and natural colors and a great sense of rhythm. Everything sounds rock solid, and you can forget that you're listening to a digital source. Does this mean that the highs are soft and forgiving? Not the least bit! They are very present and have bite. Cymbals and drums, percussion of all kind sound lively and natural like with no other amp. Punch and control also are the keyword for bass and mids. The Amity has the tightest, driest bass I've ever heard from an amp. As to the mids: they are the least striking frequency range, and this has to do with the fact that they appear as somewhat recessed -- not quite so without a comparison to the competitors or the direct path though. This doesn't harm at all the Amity's fun to play rock music. Even studio recordings sound almost like live recordings thanks to its great verve. This sound seriously reminds me of the Grado SR-325...

Its downside: e.g. Blondie's new album «The Curse of Blondie», with its plenitude of electronic instruments, sounds rather like a rock album again. The charm of the synthetic instruments with their richness of overtones isn't adequately reproduced. The extreme upper end of the audio spectrum seems to be missing, but that's just an interpretation of the mentioned phenomenon There's also some flow missing, something the EMP offers in abundance. As natural cymbals sound, a great deal of their sustain, which contains a lot of midrange components, is missing. Switching to classical orchestral music finally reveals the Amity's greatest flaw: sustain and reverberation are underrepresented, which gives the sound a distinct dryness. Nevertheless, the timbres of the classical instruments are excellently reproduced. But a symphony orchestra as a whole tends to sound rather like a chamber orchestra.

Talking about the soundstage: It's extremely large, but somewhat restricted in depth -- something that's understandable after all. Nevertheless, the musicians don't appear to play extremely close, but rather from an average, credible distance.

The Amity provides a rock solid sound with a great affinity to rock music. Detail sharpness, bass control and dynamics are outstanding. And so is the naturalness of the sonic colors without any digital flavor. Its weakness is a somewhat edge-shaped timbre, a lack of musical flow in favor of rhythm and pace. Even more than orchestral music I would call electronica the genre it likes the least, but after all it isn't really incapable to nevertheless offer an enjoyable sound with all genres, even those mentioned to be less ideally performed.

So is the Amity a pure rock amp? Not necessarily. With some headphones its dry character is clearly mitigated. But I would certainly recommend it to people who predominantly listen to rock. Although to combine it with a Grado would support the latter's colorations too much IMO. But how about the HD 580/600...


The Amity with...


...Grado SR-225

Great driving bass and sizzling treble, lacking midrange, serious lack of coherency... This is certainly not a good combination. But keep in mind that I'm not a fan of the Grado sound!


...Sennheiser HD 600

Well, this sound is really enjoyable! No obvious dryness at all but great projection even of a symphony orchestra in all its beauty and full size. Rock music makes you doubt why the HD 600 is called unsuitable for this genre.


...Sennheiser HD 650

No doubt: rock, pop and the like are the domain of this combo. The reproduction of classical and partly jazz is a bit less credible because of the now obvious lack of ambience, but the sonic balance is very good, and instrument timbres appear highly realistic. Certainly not worse than the HD 600 over-all.


...Beyerdynamic DT 880

If you think the DT-880 sounds bland, try it with the Amity! It's amazing how much Grado qualities it shows in this combination. A lot of high-frequency energy and a fast bass, not quite as impactful as the real Grados though... But if you're looking for neutral sound, this is not a too great match.


...Etymotic ER-4P/X

Yes, why not! A hot combo with lots of energy. Keep in mind that my filter- and foam-plug-modified ER-4P sounds slightly different than the stock phones. But I think this combo is a fairly good match, it just slightly emphasizes the ER-4's treble resonance (which BTW is reduced in the case of my pair).



post #2 of 5
Thanks for the review. I have actually seen about Amity before but only the name and the website, which at least then didn't give any hints to the type of the sound.
I have no principle objection to coloured components as long as they are presented as such. But I prefer to have the colouration last in the chain, i.e. the headphone or maybe the headphone cable, as this gives better control and it is easy to shift to another phone and a wide choice of alternatives are possible. I prefer the Corda + Grado alternative to Amity + HD600, becasue in the latter case, what headphone to choose when you want a more neutral presentation?
But I suspect that there are some that will think that Amity + Grado is a top choice!
post #3 of 5
Thanks, JaZZ - good review. Did you like the separate volume controls, btw?

Greetings from Munich!

Manfred / lini
post #4 of 5
Thread Starter 
Anders...
Quote:
I have no principle objection to coloured components as long as they are presented as such. But I prefer to have the colouration last in the chain, i.e. the headphone or maybe the headphone cable, as this gives better control and it is easy to shift to another phone and a wide choice of alternatives are possible.
...I understand you. But actually all amps color the sound more or less, just the majority of them not so much in the domain of the sonic balance. On the other hand I'm sure the Amity measures flat.


Manfred...
Quote:
Did you like the separate volume controls, btw?
...no, not really.


post #5 of 5
Thanks, marcel. As always, an excellent review. I was going to send an email to amity about the difference between their different HPA 5 models luckily you did it allready (my german is limited).
Once I get the amp I will add my impressions here.
AKG K1000 users, will this amp mate well with those earspeakers and through the specs would it have enough power?
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