Miracles do exist!
Review sample supplied by CH Precision
Retail Prices in the EU, incl 20% VAT:
A1.5: 34.600 euro
A1 to A1.5 upgrade: 15.200 euro
When reviewing the CH Precision C1 and A1 earlier this year, the C1 quickly established itself as the absolute best DAC that I had ever heard. Likewise, the A1 was the first amplifier that I heard to combine incredible speed, dynamics, articulation, and transparency with amazing fluidity, naturalness and overall finesse. In my book, all of these attributes just could not be combined in a single amp, but CH Precision made it happen. While it can be argued that tube amplifiers have a different set of virtues that can also be very appealing, such as richer harmonics or a more fluid presentation, none of the amps that I tried so far have been able to match the A1 on all accounts. The Zanden 8120, for example, quite uniquely combines the desirable aspects of tubes with traditional transistor strengths. While it comes closer than any tube amp I tried before, the A1 retained the lead position in terms of speed, articulation and bass control. But that’s the way that it is: tubes and transistors remain in opposing camps, even if they are getting closer to one another. In the transistor camp, it’s certainly possible to find an amp that sounds more sonorous than the A1, or one that has a richer midrange, for example, but invariably these amps perform less well in one or more other parameters. So, while it is all relative and there is no single “best” product for all tastes, it is its superb balance of virtues that, for me, makes the A1 so difficult to beat. And then, along comes the A1.5, which actually does beat the A1 at its own game, and then some! But before I proceed to the listening sessions, let me explain the differences between the A1 and the A1.5.
The most obvious difference is the size: the A1.5 has the same width and depth as the A1 but is considerably taller, 50% taller, in fact. The input- and output stages have not changed from those in the A1. The output stages have always been more powerful than required by the application and they were ultimately limited only by the power supply. The A1 already had a very large toroidal transformer and a bigger one would not fit within the existing casing. But simply upping the power was not what drove the decision to upgrade the A1, rather it was the realization of how much improvement the new “Red Caps” upgrade brought to the company’s biggest amplifier, the M1 which turned it into the M1.1. The name “Red Caps”, incidentally, stems from their color. They were ordered in red and referred to as “the red caps” internally and it has somehow become their name. When the technicians at CH tried these same “Red” capacitors in the A1, the improvement was staggering and that’s what initiated the decision to build an improved version of the A1, which would become the A1.5.
Below is the company’s official statement regarding the A1.5’s new capacitors:
As part of the A1.5’s development, CH Precision has recently compared top of the line electrolytic power capacitors from several of the most renown component manufacturers. Voltage rail ripple measurement, amplifier output noise measurement, and most importantly direct listening comparison allowed us to easily rank the tested models in term of micro and macro dynamics, noise floor and low-frequency control. After further refinement and customization with the manufacturer of the best model that we tested, we were able to finalize the A1’s bigger brother, the A1.5.
Left: A1, Right: A1.5. It took me literally no time at all to appreciate the new form factor. I think the new amp has even nicer proportions than the A1.
The new 1700VA toroidal transformer, along with the aforementioned new “Red” capacitors that increase the output rating from 100 to 150 watts into 8 ohms, combined with the new internal layout, makes for a leap in quality. According to CH Precision, the A1.5 now comes closer to the performance of their flagship, the M1.1. As I know CH Precision to be a company that is not at all in the business of making hollow statements, you better believe it! Oh, and the best part? Any existing A1 can be upgraded to an A1.5.
Another difference is in the transport screws, or rather, the lack thereof. For all CH products, the power supply sits on a metal plate that is supported by flexible Silent Blocks and with the A1 this plate needed to be fastened from the bottom using 3 big thumb screws for transport. Thanks to a smart system that restricts excessive movement but at the same time allows the required movement for the Silent Blocks to work their magic, there is no more need to flip the amp upside down and insert or remove any screws. And given its weight, that’s a very good thing!
Finally, after hearing from multiple M1 customers that they preferred using the 10% global feedback setting, it was decided to add this value to the A1.5 as well. So, now its global feedback can be set to 0, 10, 20, 40, 70 and 100 %. I quickly found that I also have a preference for the 10% setting but wherever comparisons with the A1 were in order, I used the closest setting that both amps offer, which is 20%.
Above: Settings tab, Amplifier Mode setting pop up window. This is only one of the tens of screens with settings. It’s a tweakers’ dream come true! This amp works right out of the box, though, and should you “mess up” then you can always restore the default settings very easily.
All the features of the A1 remain the same: the front panel OLED display still displays a selection of modes containing every possible aspect of the amp’s status, the amp’s entire setup menu can still be controlled via its front panel buttons or via the CH Control Android app and all the clever amplification schemes are still there. For its extensive connectivity and superb configurability, CH Precision amplifiers truly are one of a kind. For a full description of all the features, please refer to the original A1 + C1 review.
Not only a matter of power
The 100-watt A1 may not appear to be a powerhouse but I am absolutely confident that it drives virtually any loudspeaker in the world. The only limitation, ultimately, would be absolute power, which originates from its power supply. Theoretically, if you crank the volume up to ear-splitting levels while using inefficient speakers, then the limitations could become clear. But in my room, with the Wilsons WP8, this never happened, not even with the volume control at “are you crazy” level. So, one could wonder if any extra power is needed or even desirable. In my situation, honestly, I did not think so. But boy am I glad that I got the chance to hear this new amp in my system!
Traditionally, when comparing a medium-powered amplifier with a more powerful amplifier of the same brand, obviously, you get more power. And often, for better or for worse, the amp will “sound” more powerful, too. But any amplifier’s sound is the result of a delicate balance of internal circuits and decision making that is easily offset. in my experience, the increase in power usually has a detrimental effect in one or more other aspects of the amp’s sound. Speed, articulation, refinement, transient purity, airiness, fluidity… usually at least some of these areas take a step back whenever the transformer size increases or output transistors are added. It’s only logical and in some cases, the change in the amp’s sonic balance can actually have an effect that is desired by many. Oftentimes, what you get in return, along with the extra power, is a richer, fuller, more sonorous sound. Take Bryston, for example. All their amplifiers follow the same principle and are marketed as being of the same quality, differing only in power output. Still, the 3B Cubed, for example, sounds faster and more articulate than the more powerful 4B Cubed. The latter, however, has a more sonorous, creamier, richer sound that is preferred by many. I have a lot of sympathy for Bryston and am using this brand as an example only because I have reviewed a bunch of them at the same time not too long ago but, in my experience, this principle holds true for many class A or AB amplifiers.
Personally, I like my amps to be fast and articulate but I would absolutely choose the aforementioned richer sound over the alternative. You see, the other thing that can happen as the amplifier power increases is that the sound becomes ever more controlled and you start to lose the sense of life and natural flow. What I’m trying to illustrate is that, usually, the balance of virtues is shifted when going from a medium power amp to a higher power amp, even if the circuits are pretty much identical. In my case, even if the extra power would be beneficial, I did not want my A1 sound to change. For me, it already had a perfect balance. And so, rather than swapping my A1 for the A1.5 immediately, I first opted to do a comparative listening test. But I needn’t have bothered…