[jonbee]

I have the Selah Tempestas which are 85 db efficient, present a 5 ohm average and 4 ohm minimum load.
Is this considered too low an impedance for the NC400?  Does this matter all the time or primarily when the amplifier is pushed hard?

My Tempestas worked just fine with them. I ran them at 90 db all day long and they had no issues at all. Only got a little warm, and never sounded strained. Sounded fabulous. Read my impressions in this thread. A truly magnificent matchup, as several other listeners confirmed. My PS audio (IcePower) amp was rated down to 1.5 ohm loads, and the Ncores bested them in every way.
I get my modules today, and should have it up and running in a few days.

[MrAcoustat]

Hi guys newbie here on class D amplifiers, never liked what i heard before but a few weeks ago a friend invited me to his house for a session with is new amp it was his DIY Hypex Ncore NC-400 & SMPS-700 kit well it was a first for me finaly a class D that i liked i am thinking of having my friend build me mono blocks i want to know is there anything more powerful than the NC-400 & SMPS-700 duo to date i ask because they will be driving these 81db Acoustat 1+1 speakers. thank you

[cab]

You have two options: bridge two nc 400 amps DIY, or buy a commercial product, the nc1200. Commercial product will cost you around $10,000US, the bridged DIY version, less than half that much.

[OzarkTom]

MrAcoustat, the amps to go with are the Acoustat Direct Drive servo tube amps. Getting rid of those transformers is the biggest improvement that you can ever make in your sound on Acoustats. Too bad the Ncores will not DD them, or the Ncores would be just as nice. With Ncores, you will still have to go through those awful veiling transformers.

I lived with Acoustats for many years, I wish I still had a pair. Ask BPape of GLK here on AC, he will tell you how great they are. Or check out Roger Modjeski's thread, he is the current brain behind ESL's and DD tube amps.

[MrAcoustat]

Thank you for your suggestion, but you have no idea of what kind of interface i have on these Acoustat's as for tubes no thank you been there 81db output tubes every year that's for rich people not an old retired man like me.

[steve k]

 First I’d like to thank Jason for the generous sharing of these amps across the country. I was able to share this audition with 6 GAS friends and compare them to my amps.

This was a very difficult review to write. These are definitely very good amps and out of the box they are very impressive and seductive. I looked forward to hearing how they compared with my humble classDaudio amps. After a few days of listening, my impressions changed a bit.

First off my system:

Modified Magnepan IIIA’s biamped with ClassDAudio SDS 224 (120 wpc/4 ohms on mids and highs), ClassDAudio SDS258 (400wpc/4ohms on the bass)
Dahlquist LP-1 active crossover
VTL 5.5 preamp
Pioneer P-65 transport
Museatex Bitstream DAC with latest John Wright mods
VPI HW19-Jr turntable with TNT platter and Audiomods Series IV arm, SAE 1000E

While I run my system biamped, for the purposes of hearing the ncores full range, I went back to a full range setup driven by the ncores and then by my SDS258 for comparison. I consider my system to be fairly neutral to slightly warm in sound and fairly detailed.

First off, the good news. These are very fast, extremely detailed amps. They gripped my speakers with an iron first, like no other amps have before. The bass control and slam was jaw dropping. We were hearing detail from well known recordings that we hadn’t heard before. Both vinyl and digital was very punchy and dynamic. Vocals in particular were very natural and clean sounding.

We were all impressed. We then went back to my SDS 258 running full range and it was interesting to hear the reactions. Some of the comments were “darker and more musical, not as bright, deeper soundstage, not as detailed, warmer tonality.” Indeed the soundstage with the ncores was smashed flat up across the front of the speakers. It was wider but much shallower than with the classDAudio and in our laps. Another comment was that the ncores are tipped up. In my system, bright albums were unbearably so with the ncores. I honestly couldn’t listen to Alison Krauss without turning the volume down considerably. 

I’m not a detail freak. I prefer a more musical presentation if albeit giving up the last nth degree of detail retrieval and a big soundstage. System synergy is what it’s all about and I’m sure there are systems where the ncores really shine. As I said, they are very good amps, they just didn’t work well in my system. They tended to be a bit too analytical sounding and produced a shallow soundstage. The ncores have definitely taken Class D design to a new plateau, which in itself was worth hearing. Eight years ago, you couldn’t get me to buy a Class D amp. Now I think it’s the future.

Again, we all appreciated the opportunity to hear these.
Steve k

[SteveFord]

Steve,
I was hoping that these amps would make their way to you as I was really interested in your thoughts.
Oddly enough, I spent a half hour flipping through that ClassDAudio build thread in Cheap and Cheerful.

[jonbee]

Indeed the soundstage with the ncores was smashed flat up across the front of the speakers. It was wider but much shallower than with the classDAudio and in our laps. Another comment was that the ncores are tipped up. In my system, bright albums were unbearably so with the ncores. I honestly couldn’t listen to Alison Krauss without turning the volume down considerably. 

Very good write up. Matchups rule. One size will never fit all. There are many spices available to choose for the audio stew, and the ncores are but one of many good but different choices.

I also found the ncores too aggressive on top at first, but interconnect changes solved that for me. Allison Krause, on New Favorite, was sublime. Interestingly, in my rig, the soundstage depth was the deepest I've had. Maybe the dipole interacting here, somehow? Irrelevant in the end if the result is not what you're looking for.
I hope to have my ncore complete this weekend. I'll be writing more of my experiences a bit later.

[mjosef]

I am currently auditioning a fellow ACer's Ncore400 in my system, it has undergone a few enhancements, I will post another followup after the weekend...much of my earlier reservations seemed to have been overcome, but I am letting it 'soak' in over the next few days. You know, different time of the day/nite, different moods...


Edit: 9/21/12
Posting the followup here as an edit since this NCore amp is not related to the tour sample.
The short answer is; now that this amp is gone from my system, I miss it.
All the 'shortcomings' I first noted during the tour sample are gone. Midrange is now fleshed out with the right amount of weight in the lower mids, and the highs are clean and extended, resolution in spades without any edginess. Decay-time seems to be now on par with my tube amps, also the soundstage is just as deep and wide. Layering of instruments are just spooky. And the piano now sounds like a real piano.
Going back to my tube amp, my immediate impression was how 'slow' and 'thick' it sounded. 
But with a little fine-tuning I was able to emulate some of the things I loved about the Ncore, but no way could I get that lightness and speed that is the Ncore basic signature.
Maybe by next year some current owners will tire of their Ncore and be looking to move onto the next new-big-event-horizon  ... and I can pick up a used/discarded one for a bargain price. 

 

[Danny Richie]

In one way these amps proved to be just like every other digital amp out there in that they are really dependent on the power that you feed them.

And I had the luxury of being able to try them with various combination's to get a widely varied result. In some cases I have to wonder if everyone else is even getting to really hear what these amps are capable of.

Another thing to keep in mind is that I am used to a top level system and my reference amps are a pair of Dodd Audio tube amps that were a spare no expense effort. They are a $50,000 set of amps. So the bar is pretty high around here.

For my first listen of the amps I used the supplied power cables and plugged them into my balanced power supply in the same sockets that my big tube amps were plugged into. My first impression was one of wow. I thought, wow, what happened to all the highs? The whole top end lacked a ton of resolution and detail that I was used to. It was like someone hit the mute button. It wasn't like there was a defect with them or something. Many people hearing what I was hearing might have thought it to be great. But it was a long way from what I was used to. The sound stage size also folded in and everything moved in two dimensional direction.

This troubled me a bit and it moved me to experiment. So I swapped out the supplied power cables for the ones on my tube amps. Ah... the highs were back. Detail levels returned. Details levels were pretty good actually. Overall sound was not too bad. Better than any other solid state amps that have been through here. Even better than some tube amps. It wasn't quite in the same league as my tube amps, but not bad. My tube amps still added a little more image depth, with a little more body and richness. The things that you'd expect from a good tube amp. All the things that draw you into the music. These amps don't have those things, but they had no problems either.

And keep in mind that in front of these amps was a really good power cable plugged into a PI Audio Uber Buss. Then another really good power cable plugged into a Dodd Audio balanced power supply. Then another pair of really good power cables leading to the amps. So there was $5,000 worth of cables and power conditioning in front of them.

So then I decided to hear what everyone else is getting from the amps. So I took supplied power cables and plugged them into the wall. Not bad actually. Much better than using the supplied power cables with all of my power conditioning. Apparently there is a lot of filtering of the power going on with the supplied power cables. They were from Triode Wire. They highs with these cables were back, but the black background was not so black anymore and the bass response was very different. The definition and textures of the bass was gone. The bass extension was not quite the same either. They now sounded pretty bla in the bottom end.

One more trick to try. I think I know how to fix that bottom end. I then plug the Tiode power cables straight into the Uber Buss. This was a great combination. Now the bottom end came right back up and the clean tightness returned. The highs were still good too. It was a very pleasing combo. I then listened to them for several hours. The background returned to black as well. Clean spaces between the notes rather than a smudge from one note to the next.

Another thing that also keeps standing out in the back of my mind with these amps was that every time I swapped out cables on them I couldn't help but think how much performance was still being left on the table with these amps. On the back panel was one of the really cheap IEC connectors with the built in on off switches right on the connection. There was a cheap RCA to balanced adapter being used, and the binding posts looked really cheap. Just from my own experience I know there are a lot of gains to be had from the obvious upgrades. This makes me wonder also about the internals and if even more was being left on the table there too. These amps sounded really good, but they could be great.

Anyone looking at amps in this price range or above should give them a listen. I'd easily take them over any Krell, Classe, Mark Levinson or any other solid state amp that is considered a top level amp. Know though that you are not done with these by just buying the amps, or mounting the kit into a chassis. Good cabling and some power conditioning is a must.

I was also using a modded Mac Mini as a source. A Dodd Audio battery power tube pre-amp, and $2,400 worth of interconnects from Ridge Street Audio. Speaker cables were from Electra Cable. Day one I listened with Super-V's: http://gr-research.com/super-v.aspx
And day two I listened with Serenity Acoustics new Super-7.  http://www.audiocircle.com/index.php?topic=109918.0

And Jason, Thank you for letting me give these a listen.

[genjamon]

Danny, I don't think you named your high end power cables as compared to the ones supplied.  Care to share?

Thanks for the great review. My own limited experimentation with cables leads me to the same conclusion that tweaking can go a long way with these amps.

[cab]

Another thing that also keeps standing out in the back of my mind with these amps was that every time I swapped out cables on them I couldn't help but think how much performance was still being left on the table with these amps. On the back panel was one of the really cheap IEC connectors with the built in on off switches right on the connection. There was a cheap RCA to balanced adapter being used, and the binding posts looked really cheap. Just from my own experience I know there are a lot of gains to be had from the obvious upgrades. This makes me wonder also about the internals and if even more was being left on the table there too. These amps sounded really good, but they could be great.

I second that emotion....I rebuilt mine using Neutrik powercon instead of IEC, Cardas XLR connectors, all occ internal wiring (home brew power, input, and output wiring), and a new type of speaker connector (no metal) that allow you to hardwire the speakers to the amp. My results were superb-a nice improvement over the usual components/construction.

[Danny Richie]

Danny, I don't think you named your high end power cables as compared to the ones supplied.  Care to share?

They weren't a branded cable. They were custom made.

and a new type of speaker connector (no metal) that allow you to hardwire the speakers to the amp.

Sounds  a little like tube connectors.

[ted_b]

Cab,
Is yours something like a non-metallic Cardas clamp?  I loved the clamping done on my former RSA Sasons, and know that Randy (rklein) has incorporated that idea into his NCores (wire comes directly from module, through grommetted hole in case, then up to clamp; user speaker wire then added to post and voila, they are sandwiched together with clamp.)

I drew a pic here:
http://www.audiocircle.com/index.php?topic=106382.msg1094484#msg1094484

[jonbee]

In one way these amps proved to be just like every other digital amp out there in that they are really dependent on the power that you feed them.

Another thing that also keeps standing out in the back of my mind with these amps was that every time I swapped out cables on them I couldn't help but think how much performance was still being left on the table with these amps. On the back panel was one of the really cheap IEC connectors with the built in on off switches right on the connection. There was a cheap RCA to balanced adapter being used, and the binding posts looked really cheap. Just from my own experience I know there are a lot of gains to be had from the obvious upgrades. This makes me wonder also about the internals and if even more was being left on the table there too. These amps sounded really good, but they could be great.

Anyone looking at amps in this price range or above should give them a listen. I'd easily take them over any Krell, Classe, Mark Levinson or any other solid state amp that is considered a top level amp. Know though that you are not done with these by just buying the amps, or mounting the kit into a chassis. Good cabling and some power conditioning is a must.

Amen to all this. I intend to re-visit more of the internal wiring and connectors at some future date, but with my PS audio power plant, Black Sand Silver PC, cardas speaker connectors and custom hookup wire, I'm really enjoying the sound. I'm sure it is not at the level of your Dodds, but very enjoyable on its own terms- and it didn't cost $50k!

[mikeeastman]

Cab, here are some pics of custom Cardas Rhodium posts that Trung sent me, he used them on his Ncores. He said he didn't notice any difference in sound using clamp method.


 

[rklein]

I second that emotion....I rebuilt mine using Neutrik powercon instead of IEC, Cardas XLR connectors, all occ internal wiring (home brew power, input, and output wiring), and a new type of speaker connector (no metal) that allow you to hardwire the speakers to the amp. My results were superb-a nice improvement over the usual components/construction.

Hi Cab:

I plan on replacing my IEC's with the Furutech GI-10's.  Can you be more specific on your implementation of the occ internal wiring(gauge/where you bought it).  I am also interested in the speaker connectors you used.  I am currently using the cheap binding posts (Apex, jr.) that were on Jason's original tour NCores.  I drilled a hole between the posts and fitted a rubber grommet.  Then just drew my DHLabs T-14 hookup wire through the hole, tinned them into loops and am using the posts as clamps (as Ted mentioned...)

Regards,

Randy

[cab]

Will try to answer all the questions:

-Binding posts: the ones I used were prototypes for a commercial product. Can't say too much about them here, but they are similar to the modified Cardas shown above but are made of a non-metallic material and allow for direct clamping of the speaker cable to the internal wiring without grommets. I will post more info when the product is available.

-Internal wiring: I obtained the molex connectors and pins from digikey and made my own power and signal cables using 16 awg occ/teflon hookup wire from partsconnection for the power input (largest size that will work with the molex connector used) and 28 awg silver occ wire with eptfe insulation in a 8 conductor circular braid around a larger eptfe core. Wire from partsconnection, eptfe from phillips scientific. For speaker connection, 14awg occ copper/teflon pairs twisted together. I may try replacing the eptfe with cotton in the future.

-Neutrik powercon connectors: used their 30amp rated connectors. Very nice.

Hope that is of some help.

[cab]

Cab,
Is yours something like a non-metallic Cardas clamp?  I loved the clamping done on my former RSA Sasons, and know that Randy (rklein) has incorporated that idea into his NCores (wire comes directly from module, through grommetted hole in case, then up to clamp; user speaker wire then added to post and voila, they are sandwiched together with clamp.)

I drew a pic here:
http://www.audiocircle.com/index.php?topic=106382.msg1094484#msg1094484

No, different, but the result is the same...

[dBe]

In one way these amps proved to be just like every other digital amp out there in that they are really dependent on the power that you feed them.

I have not heard these amps, but I know the players here and have some additional input from another person that is not a frequenter of AC.  He is a guy that I have untimate respect for and I know how he hears.  Used to be one of the old Albuquerque Speaker Society dudes.  Anyhoo, I have some observations on power cabling/treatment in conjunction with switching power supplies and the use of power treatment with them.

I'm pulling the pin on the cable/treatment grenade right now:

Switching power supplies come in quite a few flavors.  Mostly bad.  BUT, there is that designer out there that actually considers the power supply to be part of the voice of the amp and I really do believe that this amp has one of those guys at the controls.  Everything that I have heard from people that I respect on this amp has been very positive.  Consider that I am a dyed in the wool TubeDude of the first order.  I do not, however, let that jade me to the point of saying that there are no great solid state amps.  There are PASS LABS amps that I could live with forever and never look back.  Nelson Pass is one of "those guys" that takes everything into consideration when designing his amps.  Truly a Monster Designer of the first order.  I am beginning to think that Bruno Putzeys and his team are some of "those guys", too.  Having stated my point, let me move on.

Screwing with the input of a properly designed switching power supply is a recipie for disaster.  There:  I have said it.  Same can be said for other well designed power inputs.  That is why high end cables can make a huge improvement on some pieces of gear and not on others.  That is also why some pieces of gear absolutely DO NOT like power filtration in the traditional context.  There is NO and I mean NO one size fits all cable, filter, balanced power supply or combination thereof that will be beneficial in every context.  To think so is pure ignorance.  A/C power is not the simple construct that most people see it to be.  Far from it... especially when it comes to complex systems that are digital/switching systems.  Every system is an individual.  That is why I recommend Pete's TRIODE WIRE LABS cables to my customers.  They will totally rock in some systems, but not all.  Same with mine:  different systems are different systems.  Quite frankly speaking, Pete's cables are probably better cables in a majority of systems than mine.  My cables are ruthlessly revealing and very dynamic and Petes are very round sounding.  I digress, this is not about me and Pete, but about the Ncore amps.  It is my estimation that the amps, from what I have heard, will respond to power cables in this manner: Give them good clean power with no frills and they will be happy up to a point.  A very detailed system will need a different cable from one that needs some help in that area.  It is all about system synergy.

  Simply put: WHAT SOUNDS BEST SOUNDS BEST.

My advice on the power filtration side would be to be very careful about doing anything until the word is in about what works.  Will my BUSSes work?  Maybe, I do not know.  Will a BPT package work?  I do not know.  Will a Furman whatever work?  I do not know.  Will an XYZ thingie work?  Who knows?

Bottom line on all of this is that too many people tend to think that more is more when it comes to power cabling and filtration.  In fear of cutting my (prodigious) nose off to spite my face, I am here to say: " 'Tain't so, McGee!".

Be vewwy, vewwy cawefull.

Dave