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An all triode Class A amp Review: GPinto GP-H2A

post #1 of 53
Thread Starter 

Hi folks!

There is a newcomer in town:




An All Triode, Pure Class A, Transformer-Coupled Headphone Amplifier from Italy.





I had the opportunity to thoroughly listen to the unit and I would like to share my impressions here.




There is not any serious reviews anywhere on the internet on this beauty, this is the first one.


It is a brand new design originating from Italy.


There are two versions of the same amplifier:


1. The standard version: using circuit boards and very good components

2. The exclusive version: with hard-wired audiophile components




In the above picture, you see the Exclusive version in the middle with clearly hardwired construction.

Edited by zodiac1234 - 4/9/12 at 12:37pm
post #2 of 53
Thread Starter 

Some pics of the Audio Show in Italy:










A very nice prodotti indeed...

Edited by zodiac1234 - 4/9/12 at 10:28am
post #3 of 53
Thread Starter 


The standard version in black




the standard version in Ferrari Red




the EXCLUSIVE version



As you can see, they are quite beautiful creations.

As mentioned earlier, the exclusive version is hard-wired using Audiophile quality components and some tweaking (according to the manufacturer):




post #4 of 53
Thread Starter 




I've been listening to this gorgeous amplifier for a month now.




As mentioned earlier, this is the hard-wired unit, using Audiophile-grade components, excellent wiring (presumably copper) and beautiful build.

All units are hand-built from start to finish in Italy.


It is an interesting unit -- stay tuned -- I am preparing the review text.



Edited by zodiac1234 - 4/10/12 at 11:08am
post #5 of 53

Gorgeous amp! Any words on price?

post #6 of 53
Thread Starter 
Originally Posted by mosshorn View Post

Gorgeous amp! Any words on price?



The price is 1100U$ for the standard version and 1900U$ for the EXCLUSIVE version here in Europe.


Judging from its sonic performance, it's worth every penny...


If you find anything better for under 5000 U$, please tell me about it.


The mighty Burson HA160D was my all-time reference... it was unbearable in comparison.

Edited by zodiac1234 - 4/11/12 at 7:03pm
post #7 of 53
Thread Starter 



I have had this amp for a month now and have been auditioning it several hours every day during this time.


I have also been comparing it to other units at hand.

My cans:
- Sennheiser HD600
- Sennheiser HD800
- Hifiman HE-6
- Beyerdynamic T1
- Audeze LCD-2


It is a pure Class A, all Triode, transformer-coupled design using the wonderful 12AU7 tubes.

There is not much information about the unit on the internet, however the manufacturer's homepage reads that


it is a fairly conventional 3 stage tube design.

Due to the output transformer, and the transconductance of the valves used (12AU7), this amp is unlikely to be


a good match for magnetostatic (Orthodynamic) headphones at high volume levels. I drove the Hifiman HE-6 with no probs.

So far I have compared the standard unit to the following amps.

- Lehman audio Black Cube Linear
- Beyerdynamic A1
- Burson HA-160
- Leben CS-600
- Burson HA-160D
- Naim Audio headphone amp HeadLine
- Ear Yoshino HP-4




The first thing noticed, is the most obvious with any all triode, amplifier: the high frequencies.



The highs are sooo extended, sooo sweet, sooo effortless, sooo engaging, sooo natural & sooo delicious


that you almost "feel" the music instead of "hearing" the music. Mated with Hifiman HE-6, its high frequency characteristics


is 99% identical to Sennheiser Orpheus.


I don't think I've ever heard the highs rendered so free of congestion, grain and harshness. Bravo.



The midrange is unbelievably gorgeous: very palpable, extremely natural, ver airy, textured & very very beautifully rendered.



Absolutely outstanding. 12 out of 10.


The soundstaging is beyond World Class. This was quite surprising for a transformer-coupled amplifier.

The amplifier so effortlessly recreates the 3 dimensional space of the recording it's spooky. The


objects just keep moving around in your head. Try that with a +3 000 U$ Solid State amp or the massed produced super amps.


The amplifiers low level retreival or its ability to retreive audible detail from the background is


beyond ANYTHING that I have heard (except for the HP4).


The only amp with even better performance in this area is the legendary EAR Yoshino HP4 (which is really without equal, hence the price).



The bass performance (with low impedance headphones) is unfortunately ABSENT.


(just like the Orpheus, although Orpheus is not T-coupled)

The amp is simply unable to engage the low impedance drivers with sufficient grip, power and depth,


which tend to make the overall character of the amplifier slightly lightish, but not in a negative way.


This apparent lightness is by no means difficult to inhale, or bothersome to listen to.


Remeber, its overall presentation is EXTREMELY effortless and sweet. This again is so reminiscent of the


Sennheiser Orpheus - with its phenomenal high frequency extension & not so extended low frequency response.


The word effortless keeps coming back to mind:

This very sense of effortlessness helps create a sense of tremendous "ease" and a laid-back, AIRY reproduction, FULL of details


that is so intoxicating, and soooo missing with the other amplifiers.


Don't even bother with the "top" Solid State amplifiers getting all sorts of "awards" every month.


They are light years behind THIS level of sound reproduction.

Other amps in this review just sounded so plain, lifeless, dry, harsh & monotone in comparison (with the exception of EAR Yoshino HP4).


They were simply unbearable.


My all-time love: the Burson HA-160D - just sounded terribly grainy, shut in, and colorless, like watching a Black & White TV screen as


opposed to a full-color TV.





Due to the amplifiers inability to render low frequency information with low impedance headphones, there is less body


and less of that touchable, desirable dimension in the music that only the best thermionic amps can provide (read EAR Yoshino HP4).


This would be a perfect parnter for high impedance loads; the likes of Sennheisers, Beyerdynamics, and specially Grado's.

Remeber: It does not like low impedances (nothing new here).


However the Grados are very efficient, and therefore I beleive they could still be good partners.


It is a newbie. However its sonic performance makes it an instant classic.


HD800 and the GPInto H2A sang so beautifully together that they kept reminding me of the Sennheiser Orpheus combination.


They are THAT GOOD together.


During the past couple of years, I have listened to many expensive multi-thousand dollar Super Amps,


No-Holds-Barred diy efforts & Mega+Ultra+Giga Reference amp-projects, all claiming to have discovered something


extraordinary -- maybe so -- but none have delivered the goods in my opinion, and none grabbed my attention like the Pintos.


Do yourselves a favor and listen to this incredible little amp.


Together with the Hifiman HE-6, its performance was simply mind-blowing at low volume levels. If you tried this and you can't hear it,


re-check everything, you have probably done something wrong. You don't need a fantastic source or a special setup to hear the sonics


this thing can deliver.

Unfortunately at higher volume levels & partnered with the likes of Hifimans or the Audezes, the output transformer


runs out of inductance and the frequency extensions suffer.

However mate it with a good high impedance can (more than 100 ohms) and discover what a marvelous virtuoso it is.




I can't find any amplifier in this price range that can match its sonics. Hell, I can't think of any amp costing 4 times that much


that can pull it off against the Pinto.


So the question is:


did I like it? ...

... Yeees.

Edited by zodiac1234 - 3/3/13 at 5:58pm
post #8 of 53

Hi zodiac1234,
thanks for the review and good words. We tried to do a good job. :)

We are available for any kind of information.

Kind Regards,

post #9 of 53

Thanks for taking the time to post your impressions.


However, you made some statements that are fundamentally incorrect and need to be addressed.


First, output transformers are not inherently better or worse at bass than output-transformerless amps.  It's all in the circuit design and which tubes are used.  For example, my output transformer amp (Trafomatic) has better bass response than my output-transformerless amp (Woo 3).  To simply state that all output transformer amps are bad at bass is a gross inaccuracy.


Second, output transformers are great for low impedance headphones, whereas output-transformerless amps are better for high impedance headphones.  This is because the output impedance of tubes is often higher than the low impedance of some headphones.  The output transformers change the impedance ratio making the use of low impedance headphones possible and very good sounding.  To say that output transformers do not like low impedance headphones is terribly wrong.  In fact, output transformers make low impedance headphones sound much better than without using them.


Third, certain Beyerdynamic and Sennheiser headphones are high impedance (250, 300, and 600 ohms).  However, Grados are low impedance.  Nothing in their current lineup is greater than 32 ohms.


In the end, I do appreciate your efforts and your willingness to share your thoughts.  But, these inaccuracies I pointed out do make me wonder.....

Originally Posted by zodiac1234 View Post


The bass performance (with low impedance headphones) is typical of all transformer-coupled amplifiers: ABSENT.



This would be a perfect parnter for high impedance loads; the likes of Sennheisers, Beyerdynamics, and specially Grado's.

Remeber: It does not like low impedances (nothing new here) since it is transformer-coupled.


However the Grados are very efficient, and therefore I beleive they could still be good partners.


post #10 of 53
Thread Starter 

Thank you hodgjy for your comments.




Absolutely right, using output transformers in a design doesnot mean a worse, perceived bass response.


Excellent commercial offerings exist that have great perceived bass extension AND use transformers.


I have corrected my comments.





From a technical point of view, a reduction in load impedance will lead to a higher corner frequency (less bass)


in a T-coupled output stage, unless the transformer primary and secondary inductances are accordingly scaled,


that is why there are several secondary windings for different loads (4, 8, 16) on a high quality valve amplifier.





Output transformers are extremely bad (nonlinear) components (so are capacitors) in the signal path.


They are not really great for low impedance headphones, but fairly good results (measurements) are


achieved by including the transformer in the feedback loop, the transformer-induced nonlinearities are


thus reduced by the amount of Feedback Factor applied.





OTL amplifiers, once executed correctly, can sound extremely natural:


(Transcendent Audio, Orpheus amplifier, or KG DC coupled ES headphone amp).


Technically, they are superior. There is no discussion on the subject.



However, two of my absolutely best reference headphone amps are T-coupled:


The EAR Yoshino HP4 is - to my knowledge - THE BEST headphone amplifier in the world today.


It uses transformers at both input & output, and features a very odd circuit configuration, with variable feedback.



Its sound quality is -- to say the least -- without equal, regardless of the cost. It was FAR superior to the Orpheus amp


, the SS Dynalo, and Burson offerings (HA-160D).





The reason I commented on the fact that Grados would be a good match for the Gpinto amplifier is due to their efficiency.


In addition, they posess an exagerrated bass response (look at frequency graphs) that will complement


the low frequency cutoff of Gpinto into a lowish 32 ohms.




My comments were otherwise acurrate.



thanks again for your comments.

Edited by zodiac1234 - 4/18/12 at 9:43pm
post #11 of 53

Well, I don't want to derail the spirit of this thread, which is an excellent writeup on your opinions of this amp.  But, I do disagree with your interpretations of OTL vs. transformer coupled amps, with reference to "superiority" and impedance matching.  I guess that's life and we'll have to agree to disagree.


In the end, all that matters is what our ears tell us.  I think sometimes we get too sidetracked with discussions of technical merit, when we should just talk about the music and the enjoyment it brings us.

post #12 of 53
Thread Starter 
Originally Posted by hodgjy View Post


In the end, all that matters is what our ears tell us.  I think sometimes we get too sidetracked with discussions of technical merit, when we should just talk about the music and the enjoyment it brings us.





Right of course. But as long as the musical signal is reproduced through electrical


means, the amplifier should "aim" to replicate the original signal fairly closely - at least in the frequency domain. That is


by far the least complicated problem in audio amplifier design.


Filtering the highs and lows does not occur in reality, but it does happen in transformer-coupled


amplifiers into lower impedance loads, and it profoundly effects the perceived sound.




Great care must be taken by the transformer designer and the electronics engineer to "match" the transformer secondary


impedance to the load impedance, hence sacrificing open loop gain for a wider frequency response, otherwise considerable


signal loss at the frequency extremes will occur.






Edited by zodiac1234 - 4/18/12 at 9:42pm
post #13 of 53

Thanks for the nice review!





post #14 of 53
Thread Starter 


No worries mate,


Please share with the rest of us your impressions & experiences with the GPinto GP-H2A.


Remember, they need a long burn-in (as all class A amps do), and don't forget to hook'em up with


PSU conditioners.



Edited by zodiac1234 - 4/24/12 at 12:48pm
post #15 of 53

Just received.



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