Arcam also took care to minimize the glitches and errors that tend to occur at those class G switchover points discussed above. The diodes used for this switchover are fast, premium Schottky diodes. The drivers ahead of the output stage are all run off the higher rails voltage, which lessens the slight gain step change error that can occur at switchover.
      The power amplifier section of the AVR600 uses heavy, premium 2 ounce copper for its PC board traces, for better signal conductivity and higher current capability. That's pretty unusual for a receiver.
      The PC board for this power amplifier section is also a more expensive 4 layer board, with 4 distinct layers of traces, very rarely seen in power amplifiers (or power amplifier sections of receivers). These 4 layers give the Arcam engineers much more layout flexibility, in where they can place various parts on the PC board. With this newfound flexibility, they can place components to optimize short paths between critical parts. Short paths give faster speed, as we heard in the AVR600. Short paths also allow wider bandwidth and more accurate feedback (with less phase shift and less time delay), thus giving better transparency and articulation, as we heard in the AVR600. And short paths can enable better stability into difficult loads, thus giving the AVR600 better authority and control when driving difficult loudspeaker loads, just as we heard.
      This newfound flexibility of parts layout on the PC board, deriving from its premium 4 layer design, also allows the Arcam engineers to minimize unwanted interference between and among various traces. Thus, the output traces from a stage can be placed and angled so they don't interfere with the input traces, and both can be kept from receiving interference from noisy traces or power supply traces. A multilayer PC board is a huge help in achieving this freedom from interference, because wires that cross each other at right angles don't electrically interfere with each other, but of course on a single layer PC board you can't make two traces cross each other (unless you build an overpass).
      A further sonic benefit here is the virtual elimination of a pernicious type of high frequency distortion, seen in all amplifiers (other than totally class A) that are less perfectionist in design details than the AVR600. Each power rail conductor carries only a half wave type signal, and radiates it strongly into nearby circuitry (strongly because the rails operate at high voltage and current). When the nearby circuitry (especially delicate and vulnerable circuitry carrying the audio signal) picks up this radiated half wave signal, this induced half wave signal is added to the original full wave audio signal in that nearby circuitry. This causes ugly high frequency distortion, because each half wave is a very distorted version of the full wave audio signal (that half wave could be said to have 100% even order distortion, because the other half of the full wave signal is totally zero and missing). Note that the original audio signal waveform plus a hugely distorted waveform equals a distorted audio signal waveform. Thus, in other power amplifiers, with less sophisticated perfectionist engineering design than the AVR600, this is a very real high frequency distortion problem.
      Arcam cures this distortion problem, virtually eliminating this ugly high frequency distortion, via a perfectionist design tactic, made possible by the AVR600's premium multilayer PC board. With a multilayer PC board like this, Arcam can place positive and negative power rails conductors to be intimately adjacent, right on top of each other in separate layers. By virtue of these conductors being physically and electrically intimate over their length, the radiated half wave signals from these two conductors superimpose, to form a perfect full wave replica of the audio signal. Thus their effective joint radiation, rather than being a highly distorted half wave signal that causes distortion when picked up by nearby circuitry and added there to the original audio signal - is instead a full wave signal, a virtually perfect replica of the original signal, so, when it is picked up by nearby circuitry and added to the audio signal, virtually no distortion is created. Note that the original audio signal waveform plus a little more of this same full signal waveform equals the same audio signal waveform as the original audio signal had, hence no distortion is created. This sophisticated Arcam engineering design detail helps explain why we hear the AVR600 actually having cleaner, purer high frequencies than competing units (despite class G glitches), and it corroborates and justifies the sonic findings we reached with our ears.
      The freedom from interference achieved in the AVR600, by this perfectionist 4 layer PC board in the power amplifier section, also plays a significant role in giving the AVR600 other aspects of its superb sonics. It helps make the black background silence even quieter, and helps the signal reproduction be even cleaner and more accurate. And this in turn yet further improves all those perfectionist sonic virtues we hear in the AVR600: transparent revelation of subtle program details against a black background of silence, dynamics, spatial imaging, etc.
      The surround processor section of the AVR600 ups the ante on the power amplifier section, by employing a 6 layer PC board. The surround processor section is largely of course executed in digital. Digital lines or traces radiate a lot of noise to interfere with other nearby traces. And unfortunately digital is also very sensitive and vulnerable to being interfered with by noise from other traces, including from those other nearby digital traces. Digital is vulnerable to noise because noise creates timing indeterminacy, which creates jitter, which creates distortion and dirty smearing when that digital signal is finally at some point converted to analog for listening. Therefore, digital is vulnerable to digital. In a surround processor there are so many different digital signals running around that they can mutually contaminate one another very easily, consequently making the sound of the surround processor veiled, fuzzy, smeared, and dirty, with poor spatial imaging - which is how most competing surround processors sound, especially when compared against the AVR600.
      As spectacular as the AVR600's power amplifier alone sounds (when listened to via the direct analog inputs), when the AVR600's surround processor is also engaged, the sonic results are just as spectacular, and are just as dramatic in their dominant superiority over any and every other surround processor out there. As discussed above, the AVR600 elicits 10 times the spatial volume, from a good film soundtrack or music recording, as the best previous surround processors were able to, and also is far superior in accurately reproducing and transparently revealing all kinds of sonic information, from the most delicate highs to the deepest bass impacts. A lot of credit must go to Arcam's perfectionist work in the AVR600 processor section.
      The processor's 6 layer board technology, and Arcam's hard work in exploiting this to develop optimum layout of traces and arts, surely plays a key role here. Quieting digital noise and interference makes the AVR600's final sound much cleaner, because there's far less distortion from noise/jitter; makes the sound more detailed and articulate, because there's much less time smearing of transients; makes the sound more transparently revealing, because there much less veiling garbage (arising both from the jitter distortion byproducts and from the time delayed smeared energy) obscuring the program; deepens the black background of intertransient silence; and expands spatial imaging, because the subtle cues defining space are more clearly and accurately revealed.
      Also, Arcam's work in optimizing the shortness and placement of traces, again thanks to the 6 layer technology, can make all the complex digital processing more accurately sensitive and transparently revealing, for example by making risetimes faster, which makes the zero crossing time instants more determinate, which reduces jitter, which improves the sound.
      The surround processor section in the AVR600 uses a processing chipset sourced from Analog Devices, different than the Cirrus set used in Arcam's earlier surround processor sections. This different brand of chipset has a different software menu (see below), and might well also have better sonics, thereby also making a contribution to the AVR600's spectacular perfectionist sonic performance.

      Every great product deserves some care in setup. You will be richly rewarded in the long run with better performance, if you put a little extra effort up front into the details of achieving optimum setup. Indeed, the higher the performance potential of a product, the bigger will be your reward if you set it up so that it can realize its full potential. This obviously applies to the AVR600, which has the very highest performance capabilities, and can give these to you in full if you set it up optimally.

Break-In

      Every product benefits from a break-in period. We found the break-in for the AVR600 to be pretty fast and easy, with most of the sonic benefits appearing after just 24 hours of break-in time. First, find a silver disc (music or film soundtrack) whose program has a lot of loud energy at high frequencies (big band brass, or rock with a lot of cymbal work, will do fine). Set up the AVR600 so all 7 channels are active, and select PLIIx mode so that all 7 channels will be driven by your chosen program (even if it's just a two channel stereo program). Set the AVR600's volume control to 76 (i.e. very loud but below clipping). Do NOT connect your loudspeakers to the AVR600 (the parts inside the AVR600 seem to break in happily from exercise via merely high voltage swings, without also needing current swings). Set your silver disc player on repeat play, and play that silver disc or track repeatedly for 24 hours. That's it, you're now ready to listen.
      If perchance you listen to the AVR600 before such a break-in, don't judge it yet. A new AVR600, without proper break-in, sounds to bright and brittle, too up front, and the Dolby logic steering thereby also sounds too choppy.
      Incidentally, simply playing program through the AVR600 at ordinary volume levels, while listening, is not nearly as effective at breaking it in. We evaluated one unit which had over 100 hours of playing at ordinary levels, and it still sounded too young, bright, and raw. So we applied our quick 24 break-in treatment at high levels (after disconnecting the loudspeakers), and the unit then sounded mature and great.

Power Cord

      It's no secret that the performance of upper echelon components benefits from employing a premium, high quality power cordset. Most manufacturers readily admit that the generic overseas power cord they include with each product is cheap junk. And there's a good reason why they don't make you pay for a premium power cord of their choice, since that would impose on (and unfairly penalize) your freedom to pick a premium power cord of your choice. So it's up to you to pick and supply a high quality power cordset, if you want to get the best performance from an upper echelon product, and it's our job to help you make this choice.
      Generic power cords limit and literally choke off each product's performance capability, and reduce it down to some low common denominator level. Thus, it logically follows that, the higher a product's intrinsic performance level, the more its actual delivered performance will be reduced by the generic power cord limiting it to some low common denominator level, and the more its actual delivered performance will be improved, over the performance with the stock generic cordset, when you substitute a high quality premium cordset.
      This is especially true for the AVR600. The AVR600's intrinsic performance capability is so spectacularly high that it is tragically reduced by any generic cordset (including the one that comes with the unit). And the good news is that you'll hear a huge improvement from the AVR600 when you employ a high quality power cordset. In fact, we suggest you never even listen to the AVR600 via the stock cordset (the stock cordset sounds dull, smeared, veiled, and tonally midrangy).
      Which power cordset is best for the AVR600? Arcam's previous power amplifier sections (including the P7, AVR300, and AVR350) had a bipolar solid state coloration, so they benefited from a Wan Lung power cordset, which has moderately high inductance, while still being excellent in all its conductor and dielectric characteristics. However, the AVR600 does not have this coloration; instead, it is very neutral, very accurate, and very fast. Thus, the AVR600 benefits from, and can take full advantage of, the very fastest, most revealing, most accurate, most neutral cordset. In our testing experience, the very best power cordset meeting this description is the Von Gaylord Chinchilla, so this is what we recommend for getting optimum performance from your AVR600.
      Incidentally, the Von Gaylord Chinchilla has evolved slightly over the years, so you should make sure you get and use the latest version. As of this writing, the latest (and best sounding) version has a plastic outer braid with fine (not coarse) crosshatch, and the braid is transparent (not silver, grey, or black), and the shrink wrap is blue (not black or another color). To further improve the sound of this superb power cord, carefully slit and then completely remove the blue shrink wrap boot that covers the IEC female connector (at the end which plugs into the AVR600). Leave in place the blue cylindrical sleeve that's on the cord itself, near this tail end (it's needed to terminate and damp the electromagnetic wave propagation). But, as the final fillip, very carefully cut away and remove a small portion of the length of this blue shrink wrap sleeve, cutting it away from the tail end of this sleeve (the end nearest the female IEC connector that goes into the AVR600). The reason for this last minor surgery is that the sound is best (its EM wave damping is optimal) when there's exactly 2.25 inches of unobstructed clear outer braid, between the body of the female IEC connector and the blue shrink wrap sleeve. To do this surgery, first completely remove the shrink wrap boot from the female IEC connector, then measure exactly 2.25 inches from the back of this IEC connector to a point on the blue shrink wrap sleeve, mark this point with a single edge razor (or pencil lead you can simply rub away - not with ink), then carefully cut around the circumference of the blue sleeve to isolate the small portion as a small cylinder you'll be removing, and finally slit this small cylinder open carefully, so you can discard it. Future versions of this Chinchilla power cordset might come with this blue sleeve repositioned, such that it would already be 2.25 inches away from the female IEC connector.

Grounding

      Being tied to a good quality external ground gives an audio system a precise reference point, a baseline and anchor, against which all signals are measured, throughout the system. Hence a good external system ground is important to achieving the top tier of signal accuracy, including sonic aspects like attack articulation, transient individuation, focused coherence, transparent revelation of subtle details, spatial imaging, etc. Without a good external system ground, the very same system will typically sound softer, less focused, less coherent, more smeared, more veiled, etc. - not an ugly sound, but clearly less informative.
      Now, some audio components that intrinsically sound a bit too hard or sterile (as for example the bipolar solid state sound of previous Arcam amplifiers) can sonically benefit from not being tied to an external ground, since their intrinsically hard sound is nicely and euphonically effectively offset by the softening effect of lacking an external system ground. Indeed, when reviewing Arcam's AVR300 and AVR350 receivers, we found that they sounded more musically natural when the ground switch on the back panel was set to floating, thereby disconnecting the chassis from the external ground brought in via the power cordset.
      However, the AVR600 is intrinsically so sonically natural and neutral that it does not need to be sonically tamed or offset by the softening effect of floating the chassis. Furthermore, and even more importantly, the AVR600 is intrinsically so incredibly transparent, focused, coherent, articulate, fast, etc. that it just begs to have these glorious sonic qualities exploited to the utmost, so it just begs to enjoy the increase in these qualities provided by having a good external ground as a baseline reference for all its signals. And, precisely because the AVR600's potential is so high in all these sonic virtues, the AVR600 sonically improves tremendously when provided with a good ground reference.
      We tried the AVR600 both with and without a system ground, and the sonic difference is huge. We also tried every conceivable grounding configuration for the whole system and every component in the system, to find what sounded best, so we could tell you what to simply and easily do, in order to get the best from your AVR600.
      Grounding theory suggests that a star center grounding system is the best, and we confirmed with the AVR600 that this configuration indeed does sound the best. Generally, the receiver (or preamplifier control center) functions as the hub of a system, so it is the natural obvious best choice as the star center, for a star center ground system. This means that the AVR600 should itself be the star center that is externally grounded. It also logically implies that all the other components in your system should be tied to the AVR600 as their only star ground source (ideally, tied to the AVR600 by only one ground connection wire).
      The next obvious topic is how the AVR600 itself, as the system star center, should be grounded. In Arcam's previous AVR300 and AVR350 receivers, accomplishing this grounding was as easy as flipping that little switch on the back panel, which then connected the chassis to (or disconnected the chassis from) the ground wire on the three wire power cordset. Of course, the AVR300 and AVR350, with their intrinsic bipolar sound, sounded better without a ground connection, so that little switch was actually superfluous. So Arcam eliminated this little switch in the AVR600. And ironically they then elected to design the AVR600 to be only a floating product, with no option for grounding. Ironic of course because, in the AVR600, Arcam finally have a product that sonically benefits from being grounded, indeed benefits so much that it begs to be grounded. Anyway, this Arcam decision means that the AVR600's female IEC power receptacle has only two prongs, with no possibility of connection to the ground wire of any 3 wire power cordset you might plug in there. Also, by law, Arcam is forbidden from putting a ground post on the chassis for external grounding, since the AVR600 is classified as a floating product.

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