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Class D Ncore Atsah in the house

I am currently trying out a pair of Class D Ncore NC1200 Acoustic Imagery Atsah monoblocks.

I inserted the Atsah amps in the position typically occupied by the Clayton M300 amps shown in my virtual system. There is nothing "wrong" with the Claytons, which sound fantastic. My experience has been that, in the range of high-powered SS amps, it would be hard to top the sound of the Claytons that output 300/600 wpc into 8/4 ohms, all in Class A. About a year ago a pair of the new 500 wpc Cary monoblocks I tried couldn't even come close. I have simply had an urge to try other amplifier options and couldn't pass up an opportunity to try out these Acoustic Imagery Atsah amps.

I will cut to the chase and say that I wouldn't have wasted my time with this thread had the amps not sounded good right out of the box, but they did! I will post some observations during the course of my audition and this thread will give others who have tried, or who own, various versions of the Ncore amps a chance to weigh in.

Some system stuff not posted is that with my Mac mini computer source, music files currently consist of ripped CDs using XLD and played back through Pure Music running 24 bit with Memory Play and Upsampling only multiples of 2 and limited to 88.2 kHz. I have tried a higher upsampling limit of 176.4 kHz and that sounds good too, but for now I am currently using the lower limit. Before I finish the audition, I will also try the amps using my MUSE Erato II disc player as a source.

The amps showed up stone cold (Michigan, eh) and very nicely packed in a single hard shell SKB (Pelican-style) case with dense foam padding. I sat them on top of my Claytons to make cable runs and down-the-road direct comparisons easier. They are sitting on the stock feet, on a one inch thick oak board, which is supported on hard rubber feet above the Clayton M300s. The Claytons sit on Sound Anchor amp stands spiked to the concrete floor with brass Audiopoints. The Atsah stock feet look like small-medium sized rubber feet inside of which someone has placed a small rubber ball. These are the same feet shown on pages 2 and 3 of the 6moons review, but not the spikes shown on the amp in the stacked position. I doubt the solid milled aluminum chassis needs damping but just for kicks I have placed a single brass weight (edenSound Solid Brass Damping Weights that come with EAR elastomer backing) on the top of each amp. I am using Furutech FP Alpha 3 power cables with Oyaide P-079 plugs and DIY XLR ICs made from either VH Audio OCC copper with AirLok insulation (made per the fine silver IC recipe) or braided high purity (6Ns) copper in cotton wire from Jupiter Condenser, both shielded designs, and both with Furutech FP-601/602G connectors.

After the amps warmed up for a day, I decided to try a couple of things. The inside pictures of the Atsah amps from the 6moons review show two positive and two negative output wires coming from the Ncore board to the four binding posts, one wire to each post. Most amps with bi-wire posts run a single pair of output wires and then jump to the second pair of posts. My bi-wired HT Pro 9+ speaker cables are joined at the amp end so I only use a single pair of binding posts per amp. Since I own a nice set of PCOCC wire jumpers with spades on one end and bananas on the other, I hooked them up to connect the unused pair of posts on each amp with the pair of binding posts that I have my speaker cables connected to (thereby "jumping" the amp binding posts). The result may be a jedi mind trick but I believe the dynamics may have improved a touch, or, maybe the amps were just more warmed up. Either way, I will leave the jumpers connected for my audition period. I also have an EVS ground enhancer connected to the negative post of each amp.

After listening to the amps playing through my custom SMc Audio preamp for awhile, I decided to try them with a Goldpoint discrete resistor passive volume controller. I have read reviews speaking of the (perceived) virtues of running Ncore amps directly from the volume control of certain DACs. The relatively high input impedance of the Ncore amps (between 90 - 100K ohms) should be conducive to getting good results with passive controls. In my case, the results using the Goldpoint control were the same as with my Clayton amps. The sound was quite "pure" at first but as I played more tunes there seemed to be a little something missing. Reinserting my SMc preamp resulted in an immediate increase in tone density, body and drive, with no penalties in the areas of detail or purity. I have found the SMc Audio preamp to offer truly excellent sound (compared to over 20 other expensive preamps I have had in my system) and so it will remain in use for the remainder of my audition of the Atsahs.

My only other functional observations at this time are that the amps have gotten moderately warm and that the binding post layout is different from the reviews I have seen. Regarding warmth, they are nowhere near as warm as the Claytons in Class A but the Atsahs are certainly warm to the touch and warmer than you would think from reading the Ncore literature and amp reviews. The heat is mostly on the top of the chassis and somewhat on the bottom but not so much on the sides. I suspect this is simply the milled aluminum chassis doing its job as a giant heatsink, but it may be a consideration for folks planning to put these in an enclosed cabinet. It was a pleasant surprise that the binding post layout had a single negative and a single positive post on each horizontal level, rather than the pairs being stacked vertically as shown in the pictures from the 6moons review. This allows the speaker cables to be hung off the back in a normal fashion rather than being required to run in from the sides and straddle either the power cable or the interconnect cable. I think an optimal set up would be to have the pos/neg pairs horizontal as they are on the amps I have, but to space and stagger them like this:
-...+
..-...+

Ok, how do they sound? These sounded pretty darn good stone cold right out of the box. They are absolutely quiet...to the point you need to look for the cool blue light under each amp to tell if they are turned on! I could tell right away they were contenders. I predict at the end of my time with them, if I find any shortcomings compared to the Claytons, they will be errors of ommision rather than commission. I am pretty sensitive to gear that doesn't sound "right" in some way, dry, harsh, sterile, tipped up, lacking in tone density, flat, etc. etc. These amps displayed none of those faults and have sounded better and better over the 2 days they have been turned on and playing in my system although I believe the overall burn-in has occurred previously since they are demos).

The bass from these amps is very good but not overdone. Think full, plump, defined and deep, with very good dynamics you can feel when the music demands. The excellent sound continues up the frequency range and is overall even-handed, with no evidence of discontinuities between ranges. Tone density has come on nicely as they have warmed up and dimensionality is also good. They do not provide the expansive soundstage offered by some tubed gear but in my system, and to my ears, everything is as it should be, and surprisingly similar to the Claytons in that respect. I suspect these amps may not "wow" listeners upon first hearing them, but will be valued for their realistic portrayal of the music over the long haul.

The treble seems just a touch shelved down and may not be as "sparkly" as some would wish for. The detail all seems to be there but, compared to the midrange and bass, the treble could be just a touch more prominent. This characteristic should actually be helpful in making poor recordings sound good. One thing I will try is to increase the upsampling in Pure Music to 176.4 kHz, which sometimes has the effect of increasing treble or shifting the frequency slightly upward. This treble observation is subtle and is NOT a major issue with me and IN NO WAY detracts from how good these amps sound in my system. I suspect, if there are any deficiencies compared to my Claytons they may be related to ultimate tonal saturation, which is excellent through the Class A Claytons. However, that is for another post since, for now, I am going to continue listening to these excellent sounding amps.
mitch2
m-db's avatar
m-db
931 posts
 
I've used various switching amplifiers since PS Audio introduced the $1500. HCA-2. The HCA-2 forced me to upgrade my homes VAC which turned out to improve everything not just audio and video.

Until recently, switching amplifiers have remained reasonably priced. I was able to sell my NuForce version 3 9SEs and purchase the nCore 400 kits with 1K left over. I don't doubt for a minute that this latest generation, I'll call 1200s, can be an improvement in performance.

Even so, I'm having a hard time understanding the phenomenal increase in cost. Obviously more robust power supplies, upgraded switching modules, I/O sections, and even stupidly exotic casework, will increase costs. But is it really a 10k improvement? Even with trying to keep that subjective audio aspect in my head I just can't get my arms around the cost without feeling taken advantage of? Unless, of course, class D has finally matured to audio's land of diminishing returns.

My nCores are doing uninterrupted duty in my studio but I've taken a step backwards to vacuum tubes in the main system. Even so, I'm convinced that switching amplifiers will convert even the most diehard linear solid state designs.
mitch2 OP
3,690 posts
 
I'm having a hard time understanding the phenomenal increase in cost. Obviously more robust power supplies, upgraded switching modules, I/O sections, and even stupidly exotic casework, will increase costs. But is it really a 10k improvement?
Your observation on pricing may be a factor in these not getting more attention and buyers. The two primary manufacturers are getting $9K and $12K for what is essentially an improved and more powerful version of the Hypex Ncore amplification module and switch mode power supply module available to the DIY community for about $1,500 per pair. CNC milled aluminum cases are available from AluminatiSound for about $1K per pair. Assuming the modules and cases are both a bit more expensive than the DIY versions, the $9K version doesn't seem too far outside a typical audio equipment manufacturer's margin, but the higher priced version seems priced too high to me.

This doesn't take away from how good the amps sound but I suspect the dramatic increase in cost (above what the DIY community pays for NC400 parts), skepticism because of poor sounding earlier Class D efforts, and folks waiting for the next best thing in this relatively fast moving segment of the market, may contribute to less chatter and slower sales.
electroslacker
375 posts
 
It is an odd phenomena that anything viewed as digital is considered obsolescent once a new version is announced. We're probably wired that way from watching digital computers evolve. But it creates a real financial and long-term satisfaction risk in buying very expensive "digital" amps.
mitch2 OP
3,690 posts
 
I agree with your observation Electroslacker, which is likely a result of the logarithmic rate of advancement of the technology. The other issue with these amps that some may have a hard time overcoming psychologically, is that the sum of the parts cost is low unlike conventional A or AB amplifiers with their many capacitors, expensive transformers, large cases, etc.

Small size, low heat, great bass and absolute quiet have been consistent market drivers for the technology but, with the NC1200 amps, you can also have great sound through the entire frequency spectrum (IMO) so the experiment has been to price them based on SQ, and not the cost of parts and assembly. The absence of chatter here and on other forums implies not too many buyers yet, which may be either because of the cost, or the risk of obsolescence as you pointed out or .... maybe the owners are busy listening to music.

I did find a more recent thread on the topic over at "What's Best Forum."
mapman's avatar
mapman
21,850 posts
 
ANother valid point by ESlacker!

Digital continues to evolve, unlike older analog technologies, which are fully mature these days, so ongoing change and improvement is still to be expected for teh foreseeable future.

So its like buying a computer. Invest under the assumption that things will likely still change for the better and that costs will also likely go down for what you get down the road as well.
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