{"id":24263,"date":"2020-07-12T12:35:47","date_gmt":"2020-07-12T10:35:47","guid":{"rendered":"https:\/\/www.hifi-advice.com\/blog\/?p=24263"},"modified":"2021-04-19T20:47:15","modified_gmt":"2021-04-19T18:47:15","slug":"audio-gd-master-2h-mono-power-amplifiers-1","status":"publish","type":"post","link":"https:\/\/www.hifi-advice.com\/blog\/amplifier-reviews\/power-amplifier-reviews\/audio-gd-master-2h-mono-power-amplifiers-1\/","title":{"rendered":"Audio GD Master 2H Mono Power Amplifiers"},"content":{"rendered":"

Review samples supplied by Magna Hifi<\/a>
\nRetail prices in the NL including 21% VAT:
\nMaster 1 stereo preamplifier: 1.399 euro
\nMaster 2H mono power amplifiers (pair): 4.089 euro<\/h4>\n

Master 2H power amplifiers – technical<\/h3>\n

In a fully balanced, fully discrete, two-chassis design, the 2H power amplifiers as a system employ two R-Core and two Toroid transformers with a total of 1700 Watts feeding a total of 260,000 uF divided over custom-ordered Nover capacitors which in turn feed 4 groups of class A parallel, separately regulated PSU’s to power the discrete and fully class-A gain stages which are comprised of 80 MJL4281\/4302 output transistors supplying 250W into 8 Ohms, 500W into 4 Ohms and 1000 Watts into 2 Ohms per channel. Ok, that is an impressive list for certain and it seems clear that the amps have power to spare. But at only 4.089 euros per pair, could these beasts also be refined, transparent, fast, articulate, introspective, lush, smooth, rich, musical and lyrical? You bet! As I would learn, these amps do it all. Intrigued? You should be!<\/p>\n

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The setup as used in the previous Audio GD review<\/em><\/p>\n

In an earlier review<\/a> last year, I looked at the Audio GD Master 3 stereo power amp along with the R8 DAC and the Master 1 preamp. The review you are reading now is mainly about the 2H power amplifiers but since I will be driving them primarily with the Master 1 preamp, it makes sense to revisit this extremely cost-effective yet super-high-performance product.<\/p>\n

Master 1 preamplifier revisit<\/h3>\n

With triple C-core transformers, countless regulator stages, single-polarity FET input and output buffer stages, fully balanced, class-A amplification using only discrete components and V\/I conversion for volume control via gold-contact relays and discrete 0.05% Dale film resistors and Nover capacitors, the Master 1’s list of ingredients reads like the description of a high-end preamp. Especially the volume control circuit reads like something straight out of a classic reference Mark Levinson design or a current Accuphase amplifier for that matter. Lift the hood and prepare to be amazed by the abundance of carefully-selected discrete components, all laid out perfectly. Take a second to double-check its price. Yup, that’s 1399 euros including VAT.<\/p>\n

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Now, of course, it’s one thing to have a design that looks great on paper but it’s quite another to make its sound live up to the expectations. But fear not, this it does, in spaces!<\/p>\n

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This is how I mostly used the Master 1: in the Artesania Exoteryc rack, with the Aqua Formula xHD DAC as a source.<\/em><\/p>\n

Master 1 Running In<\/h3>\n

Unlike the power amps, the Master 1 sample was brand new and that gave me a chance to assess the running-in period. As it would turn out, this provided interesting results.<\/p>\n

Straight from the box, the Master 1 preamp sounds sublimely neutral, fast, open and well-balanced. The bass is truly amazing in its combination of tightness, articulation, speed and weight and the midrange is very convincing. Eager and dynamic, the Master 1 never sounds restrained, filtered or rounded but is also not hard or in-your-face. The only sign of it needing more playing time was a certain glassiness or grain in the treble which sounded like Diana Krall’s lispy “S” but then on all tracks, not only hers. It was subtle but there was always a kind of splashiness, a subtle sanding-paper-like spike on top of energetic treble peaks, preventing them to sound entirely pure. Some people might refer to this as a transistor-y sound, and although that is generalizing the matter, I wouldn’t disagree. It is this effect that made me favor Jeff Rowland preamplifiers and power amplifiers over everything else that I had heard many system incarnations ago. Also, I did not hear this effect with the last two preamps that I reviewed which were the 3000-euro Lejonklou Sagatun<\/a> and the cough-31.000-euro-cough CH Precision L1<\/a>.<\/p>\n

But, sure enough, only one hour later, the effect was already strongly reduced at which point the preamp attained a superb balance between refinement and expressivity. The Master 1 has so much energy and conviction, such great neutrality combined with such infectious rhythmic and dynamic involvement power that it makes me stay on the couch, playing track after track after track.<\/p>\n

At this point, it was again crystal\u00a0clear to me why I was so enthusiastic about this preamp the last time. This is not merely a very good preamp for the money, it is a fantastic preamp.<\/p>\n

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The Master 1 preamp sounded great everywhere that I tried it. While it exposes the sonic nature of the rack or platform, its neutrality makes that it is not particularly fussy.<\/em><\/p>\n

I let the Master 1 preamp run during the night and indeed the next day the effect was further reduced and the sound had become even more fluid and refined. The spikes on the S’s had now all but gone and only with certain tracks, I still felt that the hi-hats could sometimes be ever so slightly raspy.<\/p>\n

Because I don’t recall having heard this with the previous Master 1 review sample, just to make sure that it was not an exemplary effect, upon checking with Dutch distributor Magna Hifi, Jos confirmed that this is indeed fully expected. According to him, I should expect the effect to have worn off in 1-2 weeks. Now, whether or not it actually took this long I honestly can’t say. somewhere between a couple of days and a week I was so lost in the performance that I forgot all about the treble. When I had a clear moment again and remembered what it was that I should have looked out for, I noticed that the effect had indeed vanished.<\/p>\n

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To be fair, even after prolonged use, I don’t think the Master 1 achieved the level of refinement of which the Lejonklou and CH Precision preamps were able. Just like the Jeff Rowland Corus<\/a> preamp, the Lejonklou Sagatun is superbly airy and finely nuanced, and in these fields, precious few others can compete. But, much in a Rowland manner, it is also quite sweet and polished and it sounds a little filtered, a little too much so for my current taste. The Master 1 has a directness and convincing purity that neither the Lejonklou nor the Rowland have. And the CH L1? Well, at its stratospheric cost, can you blame it for outperforming the humble Master 1 in certain aspects? Yes, certain<\/em> aspects, because there are two areas in which I prefer it over the costly Swiss preamp. First, it has more potent bass with more substance and drive, and second, it has an energetic purity and directness that makes the L1 sound slightly lean and slightly filtered.<\/p>\n

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While the Master 1 power amp seemed to have no real preference for interlinks, the Master 2H mono power amps sounded best to me when connected with the Vermouth Reference XLR interlinks.<\/em><\/p>\n

<\/p>\n

Transistor design with tube characteristics?<\/h3>\n

The Master 1 is a transistor preamp and it does not try to disguise this fact by sounding bloomy or otherwise rose-tinted, nor would I want it to. While it does not sound tubey (which is what good tube amps also should not sound like, btw), when fully run-in, it also does not sound transistor-y at all. Even seasoned tube-heads and transistor-haters were amazed by this preamp’s fantastically natural sound. The unit simply gets out of the way and for me, that is the best a preamp can do.<\/p>\n

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The above ACSS cables as used in the previous Audio GD review are of the smaller variant, to be used between sources and preamps.<\/em><\/p>\n

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These ACSS cables are of the bigger variant, to be used between the preamp and power amp(s).<\/em><\/p>\n

ACSS cables<\/h3>\n

As with all Audio GD products, the Master 1 and Master 2H can be connected either the conventional way or via the proprietary ACSS format. In short: this technology enables signal transfer via current, rather than via voltage, which is helpful for two reasons. First, it enables very simple circuits and simple is nearly always better. Second, the current conveyance is unaffected by the non-linearities that are inherently present in transistors.<\/p>\n

Perhaps the most well-known manufacturer to use a similar technology is Krell, who applied the Current Conveyor Technology in their products called \u201cCAST\u201d, which stands for \u201cCurrent Audio Signal Transmission\u201d. In Japan, there are a few products based on Current Conveyor Technology that they call \u201cSATRI\u201d. In Audio GD products a similar Current Conveyor Technology is applied and to avoid conflict, it is called \u201cACSS\u201d, which stands for \u201cAudio-GD Current Signal System\u201d. While CAST, SATRI, and ACSS are all forms of Current Conveyor Technology, their implementations are different. Although the three formats use different connectors, Audio GD ACSS products work just fine with KRELL “CAST” and SATRI products.\u00a0 For a more detailed description please head to the Audio GD website.<\/p>\n

Supplied with the amplifiers are the older model cables, the same ones as I have used in the earlier Audio GD review. Apart from modest cosmetic changes, the newer cables have a slightly lower noise floor which will be of most benefit with high-efficiency speakers. Since neither my Magicos nor Martin Logans are very efficient, this is of little consequence for me.<\/p>\n

Knowing from the previous review just how much the ACSS format improves the musical flow I started my listening (after the preamp had been run in) using the M-Way Natural Reference ACSS interlinks. While this combination clearly showcased the components’ superb quality in pretty much all the important fields, I felt that I obtained the best sound as well as the most neutral balance using the 1.848-euro Vermouth Reference<\/a> XLR interlinks. Although they are priced out of proportion given the amplifiers’ price, aside from providing a very linear response, these cables also injected precisely the right dose of “woodiness” to yield what I feel is a fully convincing and natural tonality. The M-Way cables that I was loaned along with the amplifiers are only one of the various models that the company offers. So, this is not to say that ACSS is not the way to go with these amps or that M-Way cables are not the ideal match but rather that it might be worth experimenting with different models and brands. For me, the Vermouths were such an excellent match that, with the exception of the comparison with the CH Precision A1.5 power amp using the CH Precision Balanced Link XLR cables, I left them connected throughout the review. The Master 2H power amps do not offer cinch connectors.<\/p>\n

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Master 3 stereo power amplifier as it was on visit for the previous Audio GD review<\/em><\/p>\n

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With 340 x 260 x 450cm, the Master 2H’s are quite formidable beasts but at 35KGs each, they are still quite manageable, unlike the hernia-inducing 50-KG CH Precision A1.5.<\/em><\/p>\n

Power Amplifiers – Master 3 versus Master 2H<\/h3>\n

Although the Master 3 stereo amp was a fine performer in the previous review, offering good value for money I found the Master 1 preamp and the R8 DAC to be the stars of the show.<\/p>\n

Only after the wheels were already set in motion for the Master 2H review in combination with the Master 1 preamp did I think of also asking for the Master 3 amp. Alas, at that time it was not available for comparison. This leaves me to wonder whether or not the 2H’s are basically a model 3 amp divided over 2 chassis or if there have been refinements, in addition to the extra transistors, of course. The Master 3 employs 12 per channel for a total of 24 while the Master 2H’s use 40 per channel for a total of 80.<\/p>\n

I guess now we will never know for sure but if you trust my listening impressions using different speakers (Wilsons and Kromas then, Logans and Magicos now) then all the evidence points to the Monos performing in a different league. And, yes, I can say that with full a lot of confidence as I am comparing them again with the CH Precision A1.5.<\/p>\n

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Listening – Master 1 with Master 2H<\/h3>\n

Ok, ok, enough with the foreplay. Let’s dive in, shall we? Unlike the Master 1 preamp, the Master 2H mono power amps were well-run in. This particular pair has been in use for 5 years and besides this sparing me the uncertainty during running in, it also nicely illustrates that these products not only provide great sound at a very friendly price, they also stand the test of time.<\/p>\n

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Since the Master 1 preamp already has my vote of confidence and seal of approval, I’ll focus on the complete system with the Master 2H monos. With music provided by the Aqua LinQ<\/a> streaming endpoint and Formula xHD<\/a> DAC (with V2 output board<\/a>) (thus not involving the CH Precision components at this stage) and driving the Magico S1 MkII’s via Driade Flow 405<\/a> speaker cables, the Master 1 and Master 2H mono amps sounded flabbergastingly good. Seriously, I am not talking good for the money, nope, their performance is seriously good full stop.<\/p>\n

At this point, the amplifiers were still positioned smack on the floor with no coupling other than the standard aluminum feet. These feet, simple as they may seem, may very well be the ideal couplers. while not spikes, they do end in a narrow 1-cm circular contact point. For a truly fair comparison I should have\u00a0 set them up on Artesania Aire platforms<\/a> like the CH A1.5 but as I have only one spare Aire, the Modular Rack (turned into floor platforms)<\/a> are not large enough and since the amplifiers sounded so great on the floor I was content to leave them where they were.<\/p>\n

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The system delivery is very energetic and dynamic, very neutral and very linear but not in the sense that there was ever too much control or a lack of musicality or flow. In fact, the Audio GD system manages to thread the fine path between fluidity and refinement on the one side and lifelike dynamics and impact on the other side. The sound is neither warm nor cool, not tubey or transitory, there is no rounding or thickening, no thinning or whitening, these components are spectacularly neutral and clearly extremely low in distortion. The presentation is highly natural, with accurate and instant transient attack as well as naturally fluid decays and that is something that is very hard to achieve. I’ve heard plenty of systems sound very refined but lacking drive and liveliness and vice versa, even in the stratospheric price range.<\/p>\n

Interestingly, I never heard the slightest indication of smear, as it can happen with amplifiers that employ a large number of transistors in parallel.<\/p>\n

Soundstaging-wise, there wasn’t much between the CH system and the Audio GD system, both sounding similarly wide and deep, which makes a strong case not only for the Audio GD pairing but also for the Italian components. If anything, I found the Audio GD + Aqua system even slightly more articulate and direct and perhaps slightly more layered in the depth plane.<\/p>\n

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It’s not quite a tie between these systems, though. The Swiss stack’s breathtaking pricetags should be good for something other than tank-like build and a slick interface, right? And indeed, the CH components do a couple of things better and other things differently.<\/p>\n

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After having also listened using the Martin Logan ESL15A’s<\/a>, having switched between the two systems and speakers repeatedly and having separated out comparisons between the Audio GD power amps in the context of the CH system, I think I have a good handle on just how the GD power amps differ from the CH power amp. It was already clear from the system performance that the Master 2H mono power amps are neither shrinking violets nor bombastic disco bashers. Just how great they are is very clear in a direct comparison with the almost 7 times as expensive CH Precision A1.5 stereo power amplifier. Using the same CH Precision Balanced Link XLR interlinks, on the surface, the Master 2H’s sound very similar in many ways. For instance, both amps are exceedingly neutral, the Master 2H’s bass is every bit as tight and well-controlled as the A1.5’s, the pacing is just as foot-tappingly fast, the midrange is just as pure and expressive, the overall dynamics are every bit as good and, rather surprisingly, the treble is almost as airy, fluid and refined. This was surprising because the Master 2H’s employ no less than 40 transistors per side! Normally, such amplifiers display a rather coarse treble in addition to having incredible muscle but not the Audio GD, this amp truly sounds like it uses only a modest amount of transistors.<\/p>\n

If there were so many similarities, where then do the two brands diverge? Well, when you get down to it, after a couple of minutes, you start to notice the differences. The Master 2H’s omit the uber-refinement that graces amps such as those by Jeff Rowland and indeed CH Precision. And this sense of micro-resolution is not even mostly apparent in the upper treble or upper midrange but rather in the actual midrange. Here is where you can hear that the CH Precision manages even better the trick of not sounding like a transistor amp and injecting the music with the kind of organic fluidity and fullness of texture that is normally more associated with tubes. Quite understandably, the Audio GD amps are<\/em> transistor amps and while they have absolutely no typical transistor flaws, ultimately, the CH Precision amp gets away from that fact just a little better. This in turn helps the lyrical aspect in performances which makes the A1.5 sound more emotionally engaging and the Master 2H soberer or matter of fact. But, honestly, that’s mostly it! Technically, the A1.5 can’t really improve on the Audio GD’s, not in terms of neutrality and transparency, not in terms of transient spontaneousness, not in terms of dynamics and impact and certainly not in terms of ultimate power, as we will see in the last part of this review which I will perform at audio buddy Niels’ place using Magico Q5 speakers.<\/p>\n

<\/p>\n

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Niels setup – JBL 250ti Jubilee<\/h3>\n

While 250\/500\/1000 Watts is a good indicator of an amplifier’s stability and power, there’s nothing quite like an actual test. My own speakers are not very efficient but neither are they extremely hard to drive. That’s why I decided to haul the mono monsters to audio buddy Niels’ place to try them with a pair of Magico Q5’s. Niels is in the fortunate position to own more than a single pair of speakers and he likes to swap them around. Right now, he has the JBL 250ti Jubilee set up instead of the Magicos. So, it made sense to first try the Master 2H’s with these speakers.<\/p>\n

After having listened to the JBLs using a Zanden 6000 integrated tube amp with newly placed tubes (which admittedly need some running in) both using the 6000 as a power amp along with the Spectral DMC-30SV preamp and straight from the Zanden 5000 Signature DAC using the 6000 as an integrated amplifier, the Audio GD amplifiers again sound remarkably good. Even though they were switched on only moments ago, the sound is immediately free-flowing and lyrical but also superbly tight, articulate, open and dynamic. We simply could not find fault with these amps’ delivery. I have heard many amps in this setup, and so far, have always preferred the Soulution 711<\/a> but in some ways, I think I now preferred the Audio GD’s. While the 711 has richer and deeper textures and even more solid bass, the treble is its weaker area and it is here where the Master 2H’s sound more fluid and organic. I almost don’t dare write it but, especially when coming from the Zanden, the Audio GD’s were remarkably non-transistor-y. It’s not that we were tricked into hearing the Zanden or any tube amp for that matter but that the Audio GD’s consistently seem to have no sound of their own and just mold themselves to the music.<\/p>\n

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Niels setup – Magico Q5<\/h3>\n<\/div>\n

Since the JBLs have been set up meticulously and Niels has not yet found a reliable method to record their precise precision, what with their angled and curved cabinets, we decided to leave them where they were and place the Magicos side by side. With close to 180 KGs per speaker, this was remarkably easy to do thanks to the castor wheels that Niels fitted prior to moving them out of the way to install the JBL’s.<\/p>\n

Switching from the JBLs to the Q5’s positioned on the outside, the imaging and focus were severely hampered so we moved them to in between the JBLs. Considering that this was still far from the perfect position, that was really not bad at all. Since I already knew from my own tests how good the M2Hs are in terms of imaging, this test in Niels’ system was mostly just to see how well the Audio GD amps would drive these speakers.<\/p>\n

With a nominal impedance of 4 ohms the Q5’s may not seem all that difficult until you realize that they have minimum values of 2.8 ohms at 40kHz, 2.75 ohms at 56Hz and 3 ohms at 200Hz, along with the kind of phase changes that bring most amplifiers to their knees, and that includes the 711 if pushed hard enough.<\/p>\n

Well, not the M2H’s! They drove the Q5’s with full confidence while sounding utterly neutral, linear, even-handed and highly refined while doing so. And, again, there was not the slightest hint of grain of smear. If there is any edginess in an amplifier, the Q5’s will let you know about it, but just as with the JBLs, we simply could not identify a single area where we could fault the amplifiers. Grinningly, I asked Niels if he could locate his torture tracks, the ones that make even his mighty Soulution 711 run out of steam eventually when played loudly enough. I handed him the remote control and prepared for the worst, only for the music to become louder and louder and louder until the woofers were hammering my chest and I started fearing for getting hearing damage. Not that there was ever any edginess or hardness, the treble simply remained pure and clean. No matter what we played or how loudly we played, these amplifiers simply did not cave in. But after 1 or 2 minutes I asked Niels to turn it down because it was just too much for me. At that point, I felt like I had been in a roller coaster thrill ride and needed some time to catch my breath.<\/p>\n

Conclusion<\/h2>\n

The Master 1 preamp majors on neutrality, dynamic expression and transparency with a natural, uncolored tonality which makes it an excellent tool to judge other components with. From using and reviewing extremely high-end components I am used to high levels of transparency but to hear a 1400-euro preamp perform on a level so close to the best I have heard is truly impressive. Because it so craftily combines analysis and neutrality with musicality and emotional involvement the Master 1 is one of my all-time favorite preamps. I won’t say that it equals the absolute best I have heard at any cost and in every aspect but it is easily the most neutral and most engaging preamp I’ve heard in the sub-10.000-euro category. And even beyond that, it equals or even outperforms some contenders in certain aspects.<\/p>\n

Like the Master 1, the Master 2H mono amplifiers amplify the whole truth and nothing but the truth. Also, like the Master 1, they combine their truthfulness with a very high level of refinement, fluidity and finesse to make for a performance that is not only spectacularly neutral but also highly natural, rhythmically infectious and hugely involving. That these amps also manage to drive the difficult to drive Magico Q5’s with a combination of iron fist-like grip and organic fluidity and no hardness ever, no matter how loud you play, is nothing short of amazing. At 4100 euros, the Master 2H’s must be the absolute best transistor amps that this amount of money can buy. Moreover, they are the best amps I’ve heard below the arm-and-leg price category of CH Precision, Analog Domain and Soulution.<\/p>\n

I have to confess to liking the Audio GD system so much that I continue listening to it, even long after completing my assessments. This indicates just how very well-designed the Audio GD components are. I absolutely love the CH components for many reasons but if I am being totally honest, I think I could also live with the Audio GD system very happily. Their no-frills, highly neutral yet unbridledly enthusiastic and expressive sound simply never bores.<\/p>\n

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\n(Master 1)<\/p>\n

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\n(Master 2H)<\/p>\n

 <\/p>\n

Associated Equipment<\/a><\/p>\n

External Links<\/h3>\n

Audio-GD Reseller (including service and repair) for Europe: Magna Hifi<\/a>
\nManufacturer: Audio GD<\/a><\/p>\n

Read Also:<\/h3>\n

Audio GD R8 DAC, Master 1 preamp, Master 3 power amp, and Magna Hifi ACSS cables<\/a><\/p>\n

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